WorldWideScience

Sample records for diffuse baryonic matter

  1. Baryonic dark matter

    International Nuclear Information System (INIS)

    Uson, Juan M.

    2000-01-01

    Many searches for baryonic dark matter have been conducted but, so far, all have been unsuccessful. Indeed, no more than 1% of the dark matter can be in the form of hydrogen burning stars. It has recently been suggested that most of the baryons in the universe are still in the form of ionized gas so that it is possible that there is no baryonic dark matter. Although it is likely that a significant fraction of the dark matter in the Milky Way is in a halo of non-baryonic matter, the data do not exclude the possibility that a considerable amount, perhaps most of it, could be in a tenuous halo of diffuse ionized gas

  2. Baryonic matter and beyond

    OpenAIRE

    Fukushima, Kenji

    2014-01-01

    We summarize recent developments in identifying the ground state of dense baryonic matter and beyond. The topics include deconfinement from baryonic matter to quark matter, a diquark mixture, topological effect coupled with chirality and density, and inhomogeneous chiral condensates.

  3. Baryonic Dark Matter

    OpenAIRE

    Silk, Joseph

    1994-01-01

    In the first two of these lectures, I present the evidence for baryonic dark matter and describe possible forms that it may take. The final lecture discusses formation of baryonic dark matter, and sets the cosmological context.

  4. Baryonic and Non-Baryonic Dark Matter

    OpenAIRE

    Carr, Bernard

    2000-01-01

    Cosmological nucleosynthesis calculations imply that there should be both non-baryonic and baryonic dark matter. Recent data suggest that some of the non-baryonic dark matter must be "hot" (i.e. massive neutrinos) and there may also be evidence for "cold" dark matter (i.e. WIMPs). If the baryonic dark matter resides in galactic halos, it is likely to be in the form of compact objects (i.e. MACHOs) and these would probably be the remnants of a first generation of pregalactic or protogalactic P...

  5. Baryonic Dark Matter

    OpenAIRE

    De Paolis, F.; Jetzer, Ph.; Ingrosso, G.; Roncadelli, M.

    1997-01-01

    Reasons supporting the idea that most of the dark matter in galaxies and clusters of galaxies is baryonic are discussed. Moreover, it is argued that most of the dark matter in galactic halos should be in the form of MACHOs and cold molecular clouds.

  6. Baryonic dark matter

    International Nuclear Information System (INIS)

    Lynden-Bell, D.; Gilmore, G.

    1990-01-01

    Dark matter, first definitely found in the large clusters of galaxies, is now known to be dominant mass in the outer parts of galaxies. All the mass definitely deduced could be made up of baryons, and this would fit well with the requirements of nucleosynthesis in a big bang of small Ω B . However, if inflation is the explanation of the expansion and large scale homogeneity of the universe and of baryon synthesis, and if the universe did not have an infinite extent at the big bang, then Ω should be minutely greater than unity. It is commonly hypothesized that most mass is composed of some unknown, non-baryonic form. This book first discusses the known forms, comets, planets, brown dwarfs, stars, gas, galaxies and Lyman α clouds in which baryons are known to exist. Limits on the amount of dark matter in baryonic form are discussed in the context of the big bang. Inhomogeneities of the right type alleviate the difficulties associated with Ω B = 1 cosmological nucleosynthesis

  7. A calculation of baryon diffusion constant in hot and dense hadronic matter based on an event generator URASiMA

    International Nuclear Information System (INIS)

    Sasaki, N.; Miyamura, O.; Nonaka, C.; Muroya, S.

    2000-01-01

    We evaluate thermodynamical quantities and transport coefficient of a dense and hot hadronic matter based on an event generator URASiMA (Ultra-Relativistic AA collision Simulator based on Multiple Scattering Algorithm). The statistical ensembles in equilibrium with fixed temperature and chemical potential are generated by imposing periodic boundary condition to the simulation of URASiMA, where energy density and baryon number density is conserved. Achievement of the thermal equilibrium and the chemical equilibrium are confirmed by the common value of slope parameter in the energy distributions and the saturation of the numbers of contained particles, respectively. By using the generated ensembles, we investigate the temperature dependence and the chemical potential dependence of the baryon diffusion constant of a dense and hot hadronic matter. (author)

  8. Baryonic dark matter

    Science.gov (United States)

    Silk, Joseph

    1991-01-01

    Both canonical primordial nucleosynthesis constraints and large-scale structure measurements, as well as observations of the fundamental cosmological parameters, appear to be consistent with the hypothesis that the universe predominantly consists of baryonic dark matter (BDM). The arguments for BDM to consist of compact objects that are either stellar relics or substellar objects are reviewed. Several techniques for searching for halo BDM are described.

  9. Compressed Baryonic Matter of Astrophysics

    OpenAIRE

    Guo, Yanjun; Xu, Renxin

    2013-01-01

    Baryonic matter in the core of a massive and evolved star is compressed significantly to form a supra-nuclear object, and compressed baryonic matter (CBM) is then produced after supernova. The state of cold matter at a few nuclear density is pedagogically reviewed, with significant attention paid to a possible quark-cluster state conjectured from an astrophysical point of view.

  10. Non-baryonic dark matter

    International Nuclear Information System (INIS)

    Berkes, I.

    1996-01-01

    This article discusses the nature of the dark matter and the possibility of the detection of non-baryonic dark matter in an underground experiment. Among the useful detectors the low temperature bolometers are considered in some detail. (author)

  11. Baryonic dark matter and Machos

    International Nuclear Information System (INIS)

    Griest, K.

    2000-01-01

    A brief description of the status of baryons in the Universe is given, along with recent results from the MACHO collaboration and their meaning. A dark matter halo consisting of baryons in the form of Machos is ruled out, leaving an elementary particle as the prime candidate for the dark matter. The observed microlensing events may make up around 20% of the dark matter in the Milky Way, or may indicate an otherwise undetected component of the Large Magellanic Cloud

  12. Precombination Cloud Collapse and Baryonic Dark Matter

    Science.gov (United States)

    Hogan, Craig J.

    1993-01-01

    A simple spherical model of dense baryon clouds in the hot big bang 'strongly nonlinear primordial isocurvature baryon fluctuations' is reviewed and used to describe the dependence of cloud behavior on the model parameters, baryon mass, and initial over-density. Gravitational collapse of clouds before and during recombination is considered including radiation diffusion and trapping, remnant type and mass, and effects on linear large-scale fluctuation modes. Sufficiently dense clouds collapse early into black holes with a minimum mass of approx. 1 solar mass, which behave dynamically like collisionless cold dark matter. Clouds below a critical over-density, however, delay collapse until recombination, remaining until then dynamically coupled to the radiation like ordinary diffuse baryons, and possibly producing remnants of other kinds and lower mass. The mean density in either type of baryonic remnant is unconstrained by observed element abundances. However, mixed or unmixed spatial variations in abundance may survive in the diffuse baryon and produce observable departures from standard predictions.

  13. Baryon asymmetry, dark matter and local baryon number

    International Nuclear Information System (INIS)

    Fileviez Pérez, Pavel; Patel, Hiren H.

    2014-01-01

    We propose a new mechanism to understand the relation between baryon and dark matter asymmetries in the universe in theories where the baryon number is a local symmetry. In these scenarios the B−L asymmetry generated through a mechanism such as leptogenesis is transferred to the dark matter and baryonic sectors through sphalerons processes which conserve total baryon number. We show that it is possible to have a consistent relation between the dark matter relic density and the baryon asymmetry in the universe even if the baryon number is broken at the low scale through the Higgs mechanism. We also discuss the case where one uses the Stueckelberg mechanism to understand the conservation of baryon number in nature.

  14. Non-baryonic dark matter

    OpenAIRE

    Berezinsky, Veniamin Sergeevich; Bottino, A; Mignola, G

    1996-01-01

    The best particle candidates for non--baryonic cold dark matter are reviewed, namely, neutralino, axion, axino and Majoron. These particles are considered in the context of cosmological models with the restrictions given by the observed mass spectrum of large scale structures, data on clusters of galaxies, age of the Universe etc.

  15. Baryons and baryon resonances in nuclear matter

    Science.gov (United States)

    Lenske, Horst; Dhar, Madhumita; Gaitanos, Theodoros; Cao, Xu

    2018-01-01

    Theoretical approaches to the production of hyperons and baryon resonances in elementary hadronic reactions and heavy ion collisions are reviewed. The focus is on the production and interactions of baryons in the lowest SU(3) flavor octet and states from the next higher SU(3) flavor decuplet. Approaches using the SU(3) formalism for interactions of mesons and baryons and effective field theory for hyperons are discussed. An overview of application to free space and in-medium baryon-baryon interactions is given and the relation to a density functional theory is indicated. The intimate connection between baryon resonances and strangeness production is shown first for reactions on the nucleon. Pion-induced hypernuclear reactions are shown to proceed essentially through the excitation of intermediate nucleon resonances. Transport theory in conjunction with a statistical fragmentation model is an appropriate description of hypernuclear production in antiproton and heavy ion induced fragmentation reactions. The excitation of subnuclear degrees of freedom in peripheral heavy ion collisions at relativistic energies is reviewed. The status of in-medium resonance physics is discussed.

  16. The Compressed Baryonic Matter experiment

    Directory of Open Access Journals (Sweden)

    Seddiki Sélim

    2014-04-01

    Full Text Available The Compressed Baryonic Matter (CBM experiment is a next-generation fixed-target detector which will operate at the future Facility for Antiproton and Ion Research (FAIR in Darmstadt. The goal of this experiment is to explore the QCD phase diagram in the region of high net baryon densities using high-energy nucleus-nucleus collisions. Its research program includes the study of the equation-of-state of nuclear matter at high baryon densities, the search for the deconfinement and chiral phase transitions and the search for the QCD critical point. The CBM detector is designed to measure both bulk observables with a large acceptance and rare diagnostic probes such as charm particles, multi-strange hyperons, and low mass vector mesons in their di-leptonic decay. The physics program of CBM will be summarized, followed by an overview of the detector concept, a selection of the expected physics performance, and the status of preparation of the experiment.

  17. Modified skyrmion in a baryonic matter

    International Nuclear Information System (INIS)

    Mishustin, I.N.

    1990-01-01

    A unified field model describing individual baryons and baryonic matter is developed. The model is based on a chiral-symmetry Lagrangian including the scalar, pion and vector fields interacting with the scalar density and the 4-current of baryons (linear σ-model supplemented by a vector field). Essentially inhomogeneous soliton solutions of the topological type (skirmions) correspond to the individual baryons, whereas homogeneous field configurations correspond to baryonic matter. Estimations show that the model predicts a correct scale of changes of the effective mass (15%) and the radius for the baryon for a normal nuclear matter density. For high baryon densities the model with a massive vector field predicts a phase transition which results in the restoration of chiral symmetry. The new state of the system is characterized by a homogeneous distribution of the meson fields and energy

  18. Equation of state of dense baryonic matter

    International Nuclear Information System (INIS)

    Weber, F.; Weigel, M.K.

    1989-01-01

    In a previous investigation we treated nuclear matter as well as neutron matter at zero and finite temperatures in the frame of different relativistic field theoretical models, but with the restriction to nucleons as the only present baryons. This approach is extended by including a larger fraction of baryons and mesons, necessary for a description of baryon matter under extreme conditions. The equation of state (EOS) is calculated in both the Hartree and Hartree-Fock (HF) approximations for dense nuclear as well as neutron matter. Self-interactions of the σ field up to fourth order have been taken into account. For the treatment of many-baryon matter in the HF approach the parameters of the theory had to be readjusted. A phase transition of both many-baryon systems (neutron as well as nuclear matter) in the high-pressure and high-energy-density region has been found. (author)

  19. Baryon destruction by asymmetric dark matter

    International Nuclear Information System (INIS)

    Davoudiasl, Hooman; Morrissey, David E.; Tulin, Sean; Sigurdson, Kris

    2011-01-01

    We investigate new and unusual signals that arise in theories where dark matter is asymmetric and carries a net antibaryon number, as may occur when the dark matter abundance is linked to the baryon abundance. Antibaryonic dark matter can cause induced nucleon decay by annihilating visible baryons through inelastic scattering. These processes lead to an effective nucleon lifetime of 10 29 -10 32 yrs in terrestrial nucleon decay experiments, if baryon number transfer between visible and dark sectors arises through new physics at the weak scale. The possibility of induced nucleon decay motivates a novel approach for direct detection of cosmic dark matter in nucleon decay experiments. Monojet searches (and related signatures) at hadron colliders also provide a complementary probe of weak-scale dark-matter-induced baryon number violation. Finally, we discuss the effects of baryon-destroying dark matter on stellar systems and show that it can be consistent with existing observations.

  20. Unified Origin for Baryonic Visible Matter and Antibaryonic Dark Matter

    International Nuclear Information System (INIS)

    Davoudiasl, Hooman; Morrissey, David E.; Tulin, Sean; Sigurdson, Kris

    2010-01-01

    We present a novel mechanism for generating both the baryon and dark matter densities of the Universe. A new Dirac fermion X carrying a conserved baryon number charge couples to the standard model quarks as well as a GeV-scale hidden sector. CP-violating decays of X, produced nonthermally in low-temperature reheating, sequester antibaryon number in the hidden sector, thereby leaving a baryon excess in the visible sector. The antibaryonic hidden states are stable dark matter. A spectacular signature of this mechanism is the baryon-destroying inelastic scattering of dark matter that can annihilate baryons at appreciable rates relevant for nucleon decay searches.

  1. Unified origin for baryonic visible matter and antibaryonic dark matter.

    Science.gov (United States)

    Davoudiasl, Hooman; Morrissey, David E; Sigurdson, Kris; Tulin, Sean

    2010-11-19

    We present a novel mechanism for generating both the baryon and dark matter densities of the Universe. A new Dirac fermion X carrying a conserved baryon number charge couples to the standard model quarks as well as a GeV-scale hidden sector. CP-violating decays of X, produced nonthermally in low-temperature reheating, sequester antibaryon number in the hidden sector, thereby leaving a baryon excess in the visible sector. The antibaryonic hidden states are stable dark matter. A spectacular signature of this mechanism is the baryon-destroying inelastic scattering of dark matter that can annihilate baryons at appreciable rates relevant for nucleon decay searches.

  2. Dark matter assimilation into the baryon asymmetry

    International Nuclear Information System (INIS)

    D'Eramo, Francesco; Fei, Lin; Thaler, Jesse

    2012-01-01

    Pure singlets are typically disfavored as dark matter candidates, since they generically have a thermal relic abundance larger than the observed value. In this paper, we propose a new dark matter mechanism called a ssimilation , which takes advantage of the baryon asymmetry of the universe to generate the correct relic abundance of singlet dark matter. Through assimilation, dark matter itself is efficiently destroyed, but dark matter number is stored in new quasi-stable heavy states which carry the baryon asymmetry. The subsequent annihilation and late-time decay of these heavy states yields (symmetric) dark matter as well as (asymmetric) standard model baryons. We study in detail the case of pure bino dark matter by augmenting the minimal supersymmetric standard model with vector-like chiral multiplets. In the parameter range where this mechanism is effective, the LHC can discover long-lived charged particles which were responsible for assimilating dark matter

  3. Baryons and baryonic matter in four-fermion interaction models

    International Nuclear Information System (INIS)

    Urlichs, K.

    2007-01-01

    In this work we discuss baryons and baryonic matter in simple four-fermion interaction theories, the Gross-Neveu model and the Nambu-Jona-Lasinio model in 1+1 and 2+1 space-time dimensions. These models are designed as toy models for dynamical symmetry breaking in strong interaction physics. Pointlike interactions (''four-fermion'' interactions) between quarks replace the full gluon mediated interaction of quantum chromodynamics. We consider the limit of a large number of fermion flavors, where a mean field approach becomes exact. This method is formulated in the language of relativistic many particle theory and is equivalent to the Hartree-Fock approximation. In 1+1 dimensions, we generalize known results on the ground state to the case where chiral symmetry is broken explicitly by a bare mass term. For the Gross-Neveu model, we derive an exact self-consistent solution for the finite density ground state, consisting of a one-dimensional array of equally spaced potential wells, a baryon crystal. For the Nambu- Jona-Lasinio model we apply the derivative expansion technique to calculate the total energy in powers of derivatives of the mean field. In a picture akin to the Skyrme model of nuclear physics, the baryon emerges as a topological soliton. The solution for both the single baryon and dense baryonic matter is given in a systematic expansion in powers of the pion mass. The solution of the Hartree-Fock problem is more complicated in 2+1 dimensions. In the massless Gross-Neveu model we derive an exact self-consistent solution by extending the baryon crystal of the 1+1 dimensional model, maintaining translational invariance in one spatial direction. This one-dimensional configuration is energetically degenerate to the translationally invariant solution, a hint in favor of a possible translational symmetry breakdown by more general geometrical structures. In the Nambu-Jona-Lasinio model, topological soliton configurations induce a finite baryon number. In contrast

  4. Baryons and baryonic matter in four-fermion interaction models

    Energy Technology Data Exchange (ETDEWEB)

    Urlichs, K.

    2007-02-23

    In this work we discuss baryons and baryonic matter in simple four-fermion interaction theories, the Gross-Neveu model and the Nambu-Jona-Lasinio model in 1+1 and 2+1 space-time dimensions. These models are designed as toy models for dynamical symmetry breaking in strong interaction physics. Pointlike interactions (''four-fermion'' interactions) between quarks replace the full gluon mediated interaction of quantum chromodynamics. We consider the limit of a large number of fermion flavors, where a mean field approach becomes exact. This method is formulated in the language of relativistic many particle theory and is equivalent to the Hartree-Fock approximation. In 1+1 dimensions, we generalize known results on the ground state to the case where chiral symmetry is broken explicitly by a bare mass term. For the Gross-Neveu model, we derive an exact self-consistent solution for the finite density ground state, consisting of a one-dimensional array of equally spaced potential wells, a baryon crystal. For the Nambu- Jona-Lasinio model we apply the derivative expansion technique to calculate the total energy in powers of derivatives of the mean field. In a picture akin to the Skyrme model of nuclear physics, the baryon emerges as a topological soliton. The solution for both the single baryon and dense baryonic matter is given in a systematic expansion in powers of the pion mass. The solution of the Hartree-Fock problem is more complicated in 2+1 dimensions. In the massless Gross-Neveu model we derive an exact self-consistent solution by extending the baryon crystal of the 1+1 dimensional model, maintaining translational invariance in one spatial direction. This one-dimensional configuration is energetically degenerate to the translationally invariant solution, a hint in favor of a possible translational symmetry breakdown by more general geometrical structures. In the Nambu-Jona-Lasinio model, topological soliton configurations induce a finite baryon

  5. On the phase strucutre of baryonic matter

    International Nuclear Information System (INIS)

    Heide, E.; Ellis, P.J.

    1991-01-01

    We have studied the phase structure of baryonic matter in a model which includes nucleons and delta resonances interacting with σ- and ω-mesons. In the mean-field approximation, the existence of phase transitions to delta matter and to a baryon-antibaryon plasma was strongly dependent on the values chosen for the equilibrium effective mass and compression modulus. When vacuum fluctuations were included, the physically acceptable solutions only yielded a liquid-gas phase transition. Further, these solutions were restricted to rather large values of the effective mass and compression modulus which did not include the currently accepted values. (orig.)

  6. The Evolution of Galaxies by the Incompatibility between Dark Matter and Baryonic Matter

    OpenAIRE

    Chung, Ding-Yu

    2001-01-01

    In this paper, the evolution of galaxies is by the incompatibility between dark matter and baryonic matter. Due to the structural difference, baryonic matter and dark matter are incompatible to each other as oil droplet and water in emulsion. In the interfacial zone between dark matter and baryonic matter, this incompatibility generates the modification of Newtonian dynamics to keep dark matter and baryonic matter apart. The five periods of baryonic structure development in the order of incre...

  7. Candidates for non-baryonic dark matter

    International Nuclear Information System (INIS)

    Fornengo, Nicolao

    2002-01-01

    This report is a brief review of the efforts to explain the nature of non-baryonic dark matter and of the studies devoted to the search for relic particles. Among the different dark matter candidates, special attention is devoted to relic neutralinos, by giving an overview of the recent calculations of its relic abundance and detection rates in a wide variety of supersymmetric schemes

  8. Candidates for non-baryonic dark matter

    OpenAIRE

    Fornengo, Nicolao

    2002-01-01

    This report is a brief review of the efforts to explain the nature of non-baryonic dark matter and of the studies devoted to the search for relic particles. Among the different dark matter candidates, special attention is devoted to relic neutralinos, by giving an overview of the recent calculations of its relic abundance and detection rates in a wide variety of supersymmetric schemes.

  9. Critical Opalescence in Baryonic QCD Matter

    OpenAIRE

    Antoniou, N. G.; Diakonos, F. K.; Kapoyannis, A. S.; Kousouris, K. S.

    2006-01-01

    We show that critical opalescence, a clear signature of second-order phase transition in conventional matter, manifests itself as critical intermittency in QCD matter produced in experiments with nuclei. This behaviour is revealed in transverse momentum spectra as a pattern of power laws in factorial moments, to all orders, associated with baryon production. This phenomenon together with a similar effect in the isoscalar sector of pions (sigma mode) provide us with a set of observables associ...

  10. Baryonic pinching of galactic dark matter halos

    International Nuclear Information System (INIS)

    Gustafsson, Michael; Fairbairn, Malcolm; Sommer-Larsen, Jesper

    2006-01-01

    High resolution cosmological N-body simulations of four galaxy-scale dark matter halos are compared to corresponding N-body/hydrodynamical simulations containing dark matter, stars and gas. The simulations without baryons share features with others described in the literature in that the dark matter density slope continuously decreases towards the center, with a density ρ DM ∝r -1.3±0.2 , at about 1% of the virial radius for our Milky Way sized galaxies. The central cusps in the simulations which also contain baryons steepen significantly, to ρ DM ∝r -1.9±0.2 , with an indication of the inner logarithmic slope converging. Models of adiabatic contraction of dark matter halos due to the central buildup of stellar/gaseous galaxies are examined. The simplest and most commonly used model, by Blumenthal et al., is shown to overestimate the central dark matter density considerably. A modified model proposed by Gnedin et al. is tested and it is shown that, while it is a considerable improvement, it is not perfect. Moreover, it is found that the contraction parameters in their model not only depend on the orbital structure of the dark-matter-only halos but also on the stellar feedback prescription which is most relevant for the baryonic distribution. Implications for dark matter annihilation at the galactic center are discussed and it is found that, although our simulations show a considerable reduced dark matter halo contraction as compared to the Blumenthal et al. model, the fluxes from dark matter annihilation are still expected to be enhanced by at least a factor of a hundred, as compared to dark-matter-only halos. Finally, it is shown that, while dark-matter-only halos are typically prolate, the dark matter halos containing baryons are mildly oblate with minor-to-major axis ratios of c/a=0.73±0.11, with their flattening aligned with the central baryonic disks

  11. The baryonic self similarity of dark matter

    International Nuclear Information System (INIS)

    Alard, C.

    2014-01-01

    The cosmological simulations indicates that dark matter halos have specific self-similar properties. However, the halo similarity is affected by the baryonic feedback. By using momentum-driven winds as a model to represent the baryon feedback, an equilibrium condition is derived which directly implies the emergence of a new type of similarity. The new self-similar solution has constant acceleration at a reference radius for both dark matter and baryons. This model receives strong support from the observations of galaxies. The new self-similar properties imply that the total acceleration at larger distances is scale-free, the transition between the dark matter and baryons dominated regime occurs at a constant acceleration, and the maximum amplitude of the velocity curve at larger distances is proportional to M 1/4 . These results demonstrate that this self-similar model is consistent with the basics of modified Newtonian dynamics (MOND) phenomenology. In agreement with the observations, the coincidence between the self-similar model and MOND breaks at the scale of clusters of galaxies. Some numerical experiments show that the behavior of the density near the origin is closely approximated by a Einasto profile.

  12. The compressed baryonic matter experiment at FAIR

    International Nuclear Information System (INIS)

    Senger, Peter

    2015-01-01

    Substantial experimental and theoretical efforts worldwide are devoted to explore the phase diagram of strongly interacting matter. At top RHIC and LHC energies, the QCD phase diagram is studied at very high temperatures and very low net-baryon densities. These conditions presumably existed in the early universe about a microsecond after the big bang. For larger net-baryon densities and lower temperatures, it is expected that the QCD phase diagram exhibits a rich structure such as a critical point, a first order phase transition between hadronic and partonic matter, or new phases like quarkyonic matter. The experimental discovery of these prominent landmarks of the QCD phase diagram would be a major breakthrough in our understanding of the properties of nuclear matter. The Compressed Baryonic Matter (CBM) experiment will be one of the major scientific pillars of the future Facility for Antiproton and Ion Research (FAIR) in Darmstadt. The goal of the CBM research program is to explore the QCD phase diagram in the region of high baryon densities using high-energy nucleus-nucleus collisions. This includes the study of the equation-of-state of nuclear matter at neutron star core densities, and the search for the deconfinement and chiral phase transitions. The CBM detector is designed to measure rare diagnostic probes such as multi-strange hyperons, charmed particles and vector mesons decaying into lepton pairs with unprecedented precision and statistics. Most of these particles will be studied for the first time in the FAIR energy range. In order to achieve the required precision, the measurements will be performed at very high reaction rates of 100 kHz to 10 MHz. This requires very fast and radiation-hard detectors, and a novel data read-out and analysis concept based on free streaming front-end electronics and a high-performance computing cluster for online event selection. The layout, the physics performance, and the status of the proposed CBM experimental facility

  13. Critical opalescence in baryonic QCD matter.

    Science.gov (United States)

    Antoniou, N G; Diakonos, F K; Kapoyannis, A S; Kousouris, K S

    2006-07-21

    We show that critical opalescence, a clear signature of second-order phase transition in conventional matter, manifests itself as critical intermittency in QCD matter produced in experiments with nuclei. This behavior is revealed in transverse momentum spectra as a pattern of power laws in factorial moments, to all orders, associated with baryon production. This phenomenon together with a similar effect in the isoscalar sector of pions (sigma mode) provide us with a set of observables associated with the search for the QCD critical point in experiments with nuclei at high energies.

  14. Critical Opalescence in Baryonic QCD Matter

    Science.gov (United States)

    Antoniou, N. G.; Diakonos, F. K.; Kapoyannis, A. S.; Kousouris, K. S.

    2006-07-01

    We show that critical opalescence, a clear signature of second-order phase transition in conventional matter, manifests itself as critical intermittency in QCD matter produced in experiments with nuclei. This behavior is revealed in transverse momentum spectra as a pattern of power laws in factorial moments, to all orders, associated with baryon production. This phenomenon together with a similar effect in the isoscalar sector of pions (sigma mode) provide us with a set of observables associated with the search for the QCD critical point in experiments with nuclei at high energies.

  15. Critical Opalescence in Baryonic QCD Matter

    International Nuclear Information System (INIS)

    Antoniou, N. G.; Diakonos, F. K.; Kapoyannis, A. S.; Kousouris, K. S.

    2006-01-01

    We show that critical opalescence, a clear signature of second-order phase transition in conventional matter, manifests itself as critical intermittency in QCD matter produced in experiments with nuclei. This behavior is revealed in transverse momentum spectra as a pattern of power laws in factorial moments, to all orders, associated with baryon production. This phenomenon together with a similar effect in the isoscalar sector of pions (sigma mode) provide us with a set of observables associated with the search for the QCD critical point in experiments with nuclei at high energies

  16. Baryons and baryonic matter in the large Nc and heavy quark limits

    International Nuclear Information System (INIS)

    Cohen, Thomas D.; Kumar, Nilay; Ndousse, Kamal K.

    2011-01-01

    This paper explores properties of baryons and finite density baryonic matter in an artificial world in which N c , the number of colors, is large and the quarks of all species are degenerate and much larger than Λ QCD . It has long been known that in large N c quantum chromodynamics (QCD), baryons composed entirely of heavy quarks are accurately described in the mean-field approximation. However, the detailed properties of baryons in the combined large N c and heavy-quark limits have not been fully explored. Here some basic properties of baryons are computed using a variational approach. At leading order in both the large N c and heavy-quark expansions the baryon mass is shown to be M baryon ≅N c M Q (1-0.054 26α-tilde s 2 ), where α-tilde s ≡N c α s . The baryon form factor is also computed. Baryonic matter, the analog of nuclear matter in this artificial world, should also be well described in the mean-field approximation. In the special case where all baryons have an identical spin-flavor structure, it is shown that in the formal heavy-quark and large N c limit interactions between baryons are strictly repulsive at low densities. The energy per baryon is computed in this limit and found to be exponentially small. It is shown that when the restriction to baryons with an identical spin-flavor structure is dropped, a phase of baryonic matter exists with a density of 2N f times that for the restricted case but with the same energy (where N f is the number of degenerate flavors). It is shown that this phase is at least metastable.

  17. The Compressed Baryonic Matter Experiment at FAIR

    International Nuclear Information System (INIS)

    Heuser, Johann M.

    2013-01-01

    The Compressed Baryonic Matter (CBM) experiment will explore the phase diagram of strongly interacting matter in the region of high net baryon densities. The experiment is being laid out for nuclear collision rates from 0.1 to 10 MHz to access a unique wide spectrum of probes, including rarest particles like hadrons containing charm quarks, or multi-strange hyperons. The physics programme will be performed with ion beams of energies up to 45 GeV/nucleon. Those will be delivered by the SIS-300 synchrotron at the completed FAIR accelerator complex. Parts of the research programme can already be addressed with the SIS-100 synchrotron at the start of FAIR operation in 2018. The initial energy range of up to 11 GeV/nucleon for heavy nuclei, 14 GeV/nucleon for light nuclei, and 29 GeV for protons, allows addressing the equation of state of compressed nuclear matter, the properties of hadrons in a dense medium, the production and propagation of charm near the production threshold, and exploring the third, strange dimension of the nuclide chart. In this article we summarize the CBM physics programme, the preparation of the detector, and give an outline of the recently begun construction of the Facility for Antiproton and Ion Research

  18. The Compressed Baryonic Matter experiment at FAIR

    Directory of Open Access Journals (Sweden)

    Höhne Claudia

    2018-01-01

    Full Text Available The CBM experiment will investigate highly compressed baryonic matter created in A+A collisions at the new FAIR research center. With a beam energy range up to 11 AGeV for the heaviest nuclei at the SIS 100 accelerator, CBM will investigate the QCD phase diagram in the intermediate range, i.e. at moderate temperatures but high net-baryon densities. This intermediate range of the QCD phase diagram is of particular interest, because a first order phase transition ending in a critical point and possibly new highdensity phases of strongly interacting matter are expected. In this range of the QCD phase diagram only exploratory measurements have been performed so far. CBM, as a next generation, high-luminosity experiment, will substantially improve our knowledge of matter created in this region of the QCD phase diagram and characterize its properties by measuring rare probes such as multi-strange hyperons, dileptons or charm, but also with event-by-event fluctuations of conserved quantities, and collective flow of identified particles. The experimental preparations with special focus on hadronic observables and strangeness is presented in terms of detector development, feasibility studies and fast track reconstruction. Preparations are progressing well such that CBM will be ready with FAIR start. As quite some detectors are ready before, they will be used as upgrades or extensions of already running experiments allowing for a rich physics program prior to FAIR start.

  19. STRANGE BARYONIC MATTER AND KAON CONDENSATION

    Czech Academy of Sciences Publication Activity Database

    Gazda, Daniel; Friedman, E.; Gal, A.; Mareš, Jiří

    2011-01-01

    Roč. 26, 3-4 (2011), s. 567-569 ISSN 0217-751X. [11th International Workshop on Meson Production, Properties and Interaction. Krakow, 10.06.2010-15.06.2010] R&D Projects: GA ČR GA202/09/1441 Institutional research plan: CEZ:AV0Z10480505 Keywords : (K)over-bar-nuclear bound states * strange baryonic matter * kaon condensation Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.053, year: 2011

  20. Dark matter, baryon asymmetry, and spontaneous B and L breaking

    International Nuclear Information System (INIS)

    Dulaney, Timothy R.; Wise, Mark B.; Perez, Pavel Fileviez

    2011-01-01

    We investigate the dark matter and the cosmological baryon asymmetry in a simple theory where baryon (B) and lepton (L) number are local gauge symmetries that are spontaneously broken. In this model, the cold dark matter candidate is the lightest new field with baryon number and its stability is an automatic consequence of the gauge symmetry. Dark matter annihilation is either through a leptophobic gauge boson whose mass must be below a TeV or through the Higgs boson. Since the mass of the leptophobic gauge boson has to be below the TeV scale, one finds that in the first scenario there is a lower bound on the elastic cross section of about 5x10 -46 cm 2 . Even though baryon number is gauged and not spontaneously broken until the weak scale, a cosmologically acceptable baryon excess is possible. There can be a tension between achieving both the measured baryon excess and the dark matter density.

  1. Shedding light on baryonic dark matter

    Science.gov (United States)

    Silk, Joseph

    1991-01-01

    Halo dark matter, if it is baryonic, may plausibly consist of compact stellar remnants. Jeans mass clouds containing 10 to the 6th to 10 to the 8th solar masses could have efficiently formed stars in the early universe and could plausibly have generated, for a suitably top-heavy stellar initial mass function, a high abundance of neutron stars as well as a small admixture of long-lived low mass stars. Within the resulting clusters of dark remnants, which eventually are tidally disrupted when halos eventually form, captures of neutron stars by nondegenerate stars resulted in formation of close binaries. These evolve to produce, by the present epoch, an observable X-ray signal associated with dark matter aggregations in galaxy cluster cores.

  2. Galaxy Formation by Cosmic Strings and Cooling of Baryonic Matter

    OpenAIRE

    Mizuo, IZAWA; Humitaka, SATO; Department of Physics, University of Tokyo; Department of Physics, Kyoto University

    1987-01-01

    Cooling and contraction of baryonic matter are investigated ina galaxy formation scenario by string loops. It is found that ~3% of virialized baryonic matter has cooled down and contracted. This virialized object may have a disk-halo structure and be considered a galaxy.

  3. Baryon-to-dark matter ratio from random angular fields

    International Nuclear Information System (INIS)

    McDonald, John

    2013-01-01

    We consider the baryon-to-dark matter ratio in models where the dark matter and baryon densities depend on angular fields θ d and θ b according to ρ d ∝θ d α and ρ b ∝θ b β , with all values of θ d and θ b being equally probable in a given randomly-selected domain. Under the assumption that anthropic selection depends primarily on the baryon density in galaxies at spherical collapse, we show that the probability density function for the baryon-to-dark matter ratio r = Ω B /Ω DM is purely statistical in nature and is independent of anthropic selection. We compute the probability density function for r as a function of α and β and show that the observed value of the baryon-to-dark matter ratio, r ≈ 1/5, is natural in this framework

  4. The Compressed Baryonic Matter Experiment at FAIR

    Directory of Open Access Journals (Sweden)

    Heuser J.M.

    2011-04-01

    Full Text Available The Compressed Baryonic Matter (CBM experiment is being planned at the international research centre FAIR, under realization next to the GSI laboratory in Darmstadt, Germany. Its physics programme addresses the QCD phase diagram in the region of highest net baryon densities. Of particular interest are the expected first order phase transition from partonic to hadronic matter, ending in a critical point, and modifications of hadron properties in the dense medium as a signal of chiral symmetry restoration. Laid out as a fixed-target experiment at the synchrotrons SIS-100/SIS-300, providing magnetic bending power of 100 and 300 T/m, the CBM detector will record both proton-nucleus and nucleus-nucleus collisions at beam energies up to 45A GeV. Hadronic, leptonic and photonic observables have to be measured with large acceptance. The nuclear interaction rates will reach up to 10 MHz to measure extremely rare probes like charm near threshold. Two versions of the experiment are being studied, optimized for either electron-hadron or muon identification, combined with silicon detector based charged-particle tracking and micro-vertex detection. The research programme will start at SIS-100 with ion beams between 2 and 11A GeV, and protons up to energies of 29 GeV using the HADES detector and an initial configuration of the CBM experiment. The CBM physics requires the development of novel detector systems, trigger and data acquisition concepts as well as innovative real-time reconstruction techniques. Progress with feasibility studies of the experiment and the development of its detector systems are discussed.

  5. Compressed baryonic matter experiment at FAIR

    Directory of Open Access Journals (Sweden)

    Jürgen Eschke

    2012-02-01

    Full Text Available The Compressed Baryonic Matter (CBM experiment is being planned at the Facility for Antiproton and Ion Research (FAIR, under realization next to the GSI laboratory in Darmstadt, Germany. Its physics programme addresses the QCD phase diagram in the region of highest net baryon densities. Of particular interest are the expected first order phase transition from partonic to hadronic matter, ending in a critical point, and modifcations of hadron properties in the dense medium as a signal of chiral symmetry restoration. Laid out as a fixed-target experiment at the synchrotrons SIS-100/SIS-300, providing magnetic bending power of 100 and 300 T/Fm, the CBM detector will record both proton-nucleus and nucleus-nucleus collisions at beam energies up to 45 AGeV. Hadronic, leptonic and photonic observables will be measured in a large acceptance. The nuclear interaction rates will reach up to 10 MHz to measure extremely rare probes like charm near threshold. This requires the development of novel detector systems, trigger and data acquisition concepts as well as in- novative real-time reconstruction techniques. A key observable of the physics program is a precise measurement of lowmass vector mesons and charmonium in their leptonic decay channel. In CBM, electrons will be identified using a gaseous RICH detector combined with several TRD detectors positioned after a system of silicon tracking stations which are located inside a magnetic dipole field. The concept of the RICH detector, results on R & D as well as feasibility studies and invariant mass distributions of charmonium will be discussed.

  6. Cold dense baryonic matter and compact stars

    International Nuclear Information System (INIS)

    Hyun Kyu Lee; Sang-Jin Sin; Mannque Rho

    2011-01-01

    Probing dense hadronic matter is thus far an uncharted field of physics. Here we give a brief summary of the highlights of what has been so far accomplished and what will be done in the years ahead by the World Class University III Project at Hanyang University in the endeavor to unravel and elucidate the multi-facet of the cold dense baryonic matter existing in the interior of the densest visible stable object in the universe, i.e. neutron stars, strangeness stars and/or quark stars, from a modest and simplified starting point of an effective field theory modeled on the premise of QCD as well as from a gravity dual approach of hQCD. The core of the matter of our research is the possible origin of the ∼ 99% of the proton mass that is to be accounted for and how the 'vacuum' can be tweaked so that the source of the mass generation can be uncovered by measurements made in terrestrial as well as space laboratories. Some of the issues treated in the program concern what can be done - both theoretically and experimentally - in anticipation of what's to come for basic physics research in Korea. (authors)

  7. Finite Volume Effect of Baryons in Strange Hadronic Matter

    Institute of Scientific and Technical Information of China (English)

    SUN Bao-Xi; LI Lei; NING Ping-Zhi; ZHAO En-Guang

    2001-01-01

    The finite volume effect of baryons in strange hadronic matter (SHM) is studied within the framework of relativistic mean-field theory. As this effect is concerned, the saturation density of SHM turns lower, and the binding energy per baryon decreases. Its influence to the compression modulus of SHM is also discussed.

  8. Non-baryonic dark matter: observational evidence and detection methods

    International Nuclear Information System (INIS)

    Bergstroem, Lars

    2000-01-01

    The evidence for the existence of dark matter in the universe is reviewed. A general picture emerges, where both baryonic and non-baryonic dark matter is needed to explain current observations. In particular, a wealth of observational information points to the existence of a non-baryonic component, contributing between around 20 and 40% of the critical mass density needed to make the universe geometrically flat on large scales. In addition, an even larger contribution from vacuum energy (or cosmological constant) is indicated by recent observations. To the theoretically favoured particle candidates for non-baryonic dark matter belong axions, supersymmetric particles, and of less importance, massive neutrinos. The theoretical foundation and experimental situation for each of these is reviewed. Direct and indirect methods for detection of supersymmetric dark matter are described in some detail. Present experiments are just reaching the required sensitivity to discover or rule out some of these candidates, and major improvements are planned over the coming years. (author)

  9. Accurate initial conditions in mixed Dark Matter--Baryon simulations

    CERN Document Server

    Valkenburg, Wessel

    2017-06-01

    We quantify the error in the results of mixed baryon--dark-matter hydrodynamic simulations, stemming from outdated approximations for the generation of initial conditions. The error at redshift 0 in contemporary large simulations, is of the order of few to ten percent in the power spectra of baryons and dark matter, and their combined total-matter power spectrum. After describing how to properly assign initial displacements and peculiar velocities to multiple species, we review several approximations: (1) {using the total-matter power spectrum to compute displacements and peculiar velocities of both fluids}, (2) scaling the linear redshift-zero power spectrum back to the initial power spectrum using the Newtonian growth factor ignoring homogeneous radiation, (3) using longitudinal-gauge velocities with synchronous-gauge densities, and (4) ignoring the phase-difference in the Fourier modes for the offset baryon grid, relative to the dark-matter grid. Three of these approximations do not take into account that ...

  10. Self-Energy of Decuplet Baryons in Nuclear Matter

    OpenAIRE

    Ouellette, Stephen M.; Seki, Ryoichi

    1997-01-01

    We calculate, in chiral perturbation theory, the change in the self-energy of decuplet baryons in nuclear matter. These self-energy shifts are relevant in studies of meson-nucleus scattering and of neutron stars. Our results are leading order in an expansion in powers of the ratio of characteristic momenta to the chiral symmetry-breaking scale (or the nucleon mass). Included are contact diagrams generated by 4-baryon operators, which were neglected in earlier studies for the $\\Delta$ isomulti...

  11. Baryonic distributions in galaxy dark matter haloes - II. Final results

    Science.gov (United States)

    Richards, Emily E.; van Zee, L.; Barnes, K. L.; Staudaher, S.; Dale, D. A.; Braun, T. T.; Wavle, D. C.; Dalcanton, J. J.; Bullock, J. S.; Chandar, R.

    2018-06-01

    Re-creating the observed diversity in the organization of baryonic mass within dark matter haloes represents a key challenge for galaxy formation models. To address the growth of galaxy discs in dark matter haloes, we have constrained the distribution of baryonic and non-baryonic matter in a statistically representative sample of 44 nearby galaxies defined from the Extended Disk Galaxy Exploration Science (EDGES) Survey. The gravitational potentials of each galaxy are traced using rotation curves derived from new and archival radio synthesis observations of neutral hydrogen (H I). The measured rotation curves are decomposed into baryonic and dark matter halo components using 3.6 μm images for the stellar content, the H I observations for the atomic gas component, and, when available, CO data from the literature for the molecular gas component. The H I kinematics are supplemented with optical integral field spectroscopic (IFS) observations to measure the central ionized gas kinematics in 26 galaxies, including 13 galaxies that are presented for the first time in this paper. Distributions of baryonic-to-total mass ratios are determined from the rotation curve decompositions under different assumptions about the contribution of the stellar component and are compared to global and radial properties of the dominant stellar populations extracted from optical and near-infrared photometry. Galaxies are grouped into clusters of similar baryonic-to-total mass distributions to examine whether they also exhibit similar star and gas properties. The radial distribution of baryonic-to-total mass in a galaxy does not appear to correlate with any characteristics of its star formation history.

  12. Chiral gravitational waves and baryon superfluid dark matter

    Science.gov (United States)

    Alexander, Stephon; McDonough, Evan; Spergel, David N.

    2018-05-01

    We develop a unified model of darkgenesis and baryogenesis involving strongly interacting dark quarks, utilizing the gravitational anomaly of chiral gauge theories. In these models, both the visible and dark baryon asymmetries are generated by the gravitational anomaly induced by the presence of chiral primordial gravitational waves. We provide a concrete model of an SU(2) gauge theory with two massless quarks. In this model, the dark quarks condense and form a dark baryon charge superfluid (DBS), in which the Higgs-mode acts as cold dark matter. We elucidate the essential features of this dark matter scenario and discuss its phenomenological prospects.

  13. Calculation of baryon chemical potential and strangeness chemical potential in resonance matter

    International Nuclear Information System (INIS)

    Fu Yuanyong; Hu Shouyang; Lu Zhongdao

    2006-01-01

    Based on the high energy heavy-ion collisions statistical model, the baryon chemical potential and strangeness chemical potential are calculated for resonance matter with net baryon density and net strangeness density under given temperature. Furthermore, the relationship between net baryon density, net strangeness density and baryon chemical potential, strangeness chemical potential are analyzed. The results show that baryon chemical potential and strangeness chemical potential increase with net baryon density and net strangeness density increasing, the change of net baryon density affects baryon chemical potential and strangeness chemical potential more strongly than the change of net strangeness density. (authors)

  14. Moduli induced cogenesis of baryon asymmetry and dark matter

    Directory of Open Access Journals (Sweden)

    Mansi Dhuria

    2016-05-01

    Full Text Available We study a cogenesis mechanism in which the observed baryon asymmetry of the universe and the dark matter abundance can be produced simultaneously at low reheating temperature without violating baryon number in the fundamental interactions. In particular, we consider a model which can be realized in the context of type IIB large volume string compactifications. The matter superfields in this model include additional pairs of color triplet and singlet superfields in addition to the Minimal Supersymmetric Standard Model (MSSM superfields. Assuming that the mass of the additional singlet fermions is O(GeV and of the color triplet fermions is O(TeV, we show that the modulus dominantly decays into the additional color triplet superfields. After soft supersymmetry (SUSY breaking, the lightest eigenstate of scalar component of color triplet superfield further decays into fermionic component of singlet superfield and quarks without violating baryon number. Imposing discrete Z2 symmetry, it follows that the singlet fermion will not further decay into the SM particles and therefore it can be considered as a stable asymmetric dark matter (ADM component. We find that the decay of the lightest eigenstate of scalar component of color triplet superfield gives the observed baryon asymmetry in the visible sector, an asymmetric dark matter component with the right abundance and naturally explains cosmic coincidence.

  15. Helioseismology with long-range dark matter-baryon interactions

    DEFF Research Database (Denmark)

    Lopes, I.; Panci, Paolo; Silk, J.

    2014-01-01

    Assuming the existence of a primordial asymmetry in the dark sector, we study how long-range dark matter (DM)-baryon interactions, induced by the kinetic mixing of a new U(1) gauge boson and a photon, affect the evolution of the Sun and, in turn, the sound speed the profile obtained from...

  16. Measurement of matter-antimatter differences in beauty baryon decays

    NARCIS (Netherlands)

    Aaij, R.; Adeva, B.; Adinolfi, M.; Ajaltouni, Z.; Akar, S.; Albrecht, J.; Alessio, F.; Alexander, M.; Ali, S.; Alkhazov, G.; Alvarez Cartelle, P.; Alves, A. A.; Amato, S.; Amerio, S.; Amhis, Y.; Everse, LA; Anderlini, L.; Andreassi, G.; Andreotti, M.; Andrews, J.E.; Appleby, R. B.; Archilli, F.; d'Argent, P.; Arnau Romeu, J.; Artamonov, A.; Artuso, M.; Aslanides, E.; Auriemma, G.; Baalouch, M.; Babuschkin, I.; Carvalho Akiba, K.; Coco, V.; David, P. N.Y.; De Bruyn, K.; Ferro-Luzzi, M.; Ketel, T.; Koopman, R. F.; Van Leerdam, J.; Merk, M.; Onderwater, C. J.G.; Raven, G.; Schiller, M.; Serra, N.; Snoek, H.; Storaci, B.; Syropoulos, V.; Van Tilburg, J.; Tolk, S.; Tsopelas, P.; Tuning, N.

    Differences in the behaviour of matter and antimatter have been observed in K and B meson decays, but not yet in any baryon decay. Such differences are associated with the non-invariance of fundamental interactions under the combined charge-conjugation and parity transformations, known as CP

  17. Measurement of matter-antimatter differences in beauty baryon decays

    NARCIS (Netherlands)

    Dufour, L.; Mulder, M; Onderwater, C. J. G.; Pellegrino, A.; Tolk, S.; van Veghel, M.

    Differences in the behaviour of matter and antimatter have been observed in K and B meson decays, but not yet in any baryon decay. Such differences are associated with the non-invariance of fundamental interactions under the combined chargeconjugation and parity transformations, known as CP

  18. Inside charged black holes. II. Baryons plus dark matter

    International Nuclear Information System (INIS)

    Hamilton, Andrew J.S.; Pollack, Scott E.

    2005-01-01

    This is the second of two companion papers on the interior structure of self-similar accreting charged black holes. In the first paper, the black hole was allowed to accrete only a single fluid of charged baryons. In this second paper, the black hole is allowed to accrete in addition a neutral fluid of almost noninteracting dark matter. Relativistic streaming between outgoing baryons and ingoing dark matter leads to mass inflation near the inner horizon. When enough dark matter has been accreted that the center-of-mass frame near the inner horizon is ingoing, then mass inflation ceases and the fluid collapses to a central singularity. A null singularity does not form on the Cauchy horizon. Although the simultaneous presence of ingoing and outgoing fluids near the inner horizon is essential to mass inflation, reducing one or the other of the ingoing dark matter or outgoing baryonic streams to a trace relative to the other stream makes mass inflation more extreme, not the other way around as one might naively have expected. Consequently, if the dark matter has a finite cross section for being absorbed into the baryonic fluid, then the reduction of the amount of ingoing dark matter merely makes inflation more extreme, the interior mass exponentiating more rapidly and to a larger value before mass inflation ceases. However, if the dark matter absorption cross section is effectively infinite at high collision energy, so that the ingoing dark matter stream disappears completely, then the outgoing baryonic fluid can drop through the Cauchy horizon. In all cases, as the baryons and the dark matter voyage to their diverse fates inside the black hole, they only ever see a finite amount of time pass by in the outside universe. Thus the solutions do not depend on what happens in the infinite past or future. We discuss in some detail the physical mechanism that drives mass inflation. Although the gravitational force is inward, inward means opposite direction for ingoing and

  19. Asymmetric dark matter, baryon asymmetry and lepton number violation

    OpenAIRE

    Frandsen, Mads T.; Hagedorn, Claudia; Huang, Wei-Chih; Molinaro, Emiliano; Päs, Heinrich

    2018-01-01

    We study the effect of lepton number violation (LNV) on baryon asymmetry, generated in the early Universe, in the presence of a dark sector with a global symmetry U(1)X , featuring asymmetric dark matter (ADM). We show that in general LNV, observable at the LHC or in neutrinoless double beta decay experiments, cannot wash out a baryon asymmetry generated at higher scales, unlike in scenarios without such dark sector. An observation of LNV at the TeV scale may thus support ADM scenarios. Consi...

  20. Layers of deformed instantons in holographic baryonic matter

    Energy Technology Data Exchange (ETDEWEB)

    Preis, Florian [Institut für Theoretische Physik, Technische Universität Wien,1040 Vienna (Austria); Schmitt, Andreas [Mathematical Sciences and STAG Research Centre, University of Southampton,Southampton SO17 1BJ (United Kingdom)

    2016-07-01

    We discuss homogeneous baryonic matter in the decompactified limit of the Sakai-Sugimoto model, improving existing approximations based on flat-space instantons. We allow for an anisotropic deformation of the instantons in the holographic and spatial directions and for a density-dependent distribution of arbitrarily many instanton layers in the bulk. Within our approximation, the baryon onset turns out to be a second-order phase transition, at odds with nature, and there is no transition to quark matter at high densities, at odds with expectations from QCD. This changes when we impose certain constraints on the shape of single instantons, motivated by known features of holographic baryons in the vacuum. Then, a first-order baryon onset and chiral restoration at high density are possible, and at sufficiently large densities two instanton layers are formed dynamically. Our results are a further step towards describing realistic, strongly interacting matter over a large density regime within a single model, desirable for studies of compact stars.

  1. Direct detection of non-baryonic dark matter

    International Nuclear Information System (INIS)

    Nollez, G.

    2003-01-01

    Baryonic matter, which constitutes stars and galaxies, amounts to a few percents of the mass of the universe in agreement with the theory of the big-bang nucleosynthesis. Most of the matter in the universe (approximately 85%) is then non-baryonic and dark. One of the most favoured hypothesis is that this non-baryonic dark matter is constituted by a new type, still undiscovered, of elementary weakly interacting massive particles (wimps). These hypothetical particles would appear as thermal relics from the big-bang era during which they were created. A rich spectrum of new elementary particles is predicted by supersymmetry, the lightest of which is the neutralino. If the dark matter halo of our Milky-way is made of neutralinos, their detection in terrestrial detectors should be possible. Neutralinos are coupled to matter through the electroweak interaction, this implies that the detection rate is extraordinary low. About 10 experiments in the world are dedicated to the search after wimps. A first group of experiments (HDMS, IGEX, DAMA and Zeplin) use 'classical' detectors of nuclear physics, germanium semiconductor diodes or NaI scintillators. A second group (CDMS, Edelweiss) gathers cryogenic phonon ionisation experiments and a third group (CRESST, Rosebud) is based on cryogenic phonon-light experiments. Till now no wimps has been clearly detected, the direct detection story is obviously not concluded, most of the future experiments aim to reach a sensitivity of 10 -44 cm 2 . (A.C.)

  2. Tying dark matter to baryons with self-interactions.

    Science.gov (United States)

    Kaplinghat, Manoj; Keeley, Ryan E; Linden, Tim; Yu, Hai-Bo

    2014-07-11

    Self-interacting dark matter (SIDM) models have been proposed to solve the small-scale issues with the collisionless cold dark matter paradigm. We derive equilibrium solutions in these SIDM models for the dark matter halo density profile including the gravitational potential of both baryons and dark matter. Self-interactions drive dark matter to be isothermal and this ties the core sizes and shapes of dark matter halos to the spatial distribution of the stars, a radical departure from previous expectations and from cold dark matter predictions. Compared to predictions of SIDM-only simulations, the core sizes are smaller and the core densities are higher, with the largest effects in baryon-dominated galaxies. As an example, we find a core size around 0.3 kpc for dark matter in the Milky Way, more than an order of magnitude smaller than the core size from SIDM-only simulations, which has important implications for indirect searches of SIDM candidates.

  3. Spinodal instability of baryon-rich quark matter

    International Nuclear Information System (INIS)

    Li, Feng; Ko, Che Ming

    2017-01-01

    The spinodal instabilities of both confined and expanding baryon-rich quark matters are studied in a transport model derived from the Nambu-Jona-Lasino model. Appreciable higher-order density moments are seen as a result of the first-order phase transition in both cases. The skewness of the quark number event-by-event distribution in a small subvolume of the system becomes appreciable for the confined quark matter. For the expanding quark matter, the density fluctuations lead to enhanced anisotropic flows and dilepton yield. (paper)

  4. Ultimate energy density of observable cold baryonic matter.

    Science.gov (United States)

    Lattimer, James M; Prakash, Madappa

    2005-03-25

    We demonstrate that the largest measured mass of a neutron star establishes an upper bound to the energy density of observable cold baryonic matter. An equation of state-independent expression satisfied by both normal neutron stars and self-bound quark matter stars is derived for the largest energy density of matter inside stars as a function of their masses. The largest observed mass sets the lowest upper limit to the density. Implications from existing and future neutron star mass measurements are discussed.

  5. Sterile neutrinos as the origin of dark and baryonic matter.

    Science.gov (United States)

    Canetti, Laurent; Drewes, Marco; Shaposhnikov, Mikhail

    2013-02-08

    We demonstrate for the first time that three sterile neutrinos alone can simultaneously explain neutrino oscillations, the observed dark matter, and the baryon asymmetry of the Universe without new physics above the Fermi scale. The key new point of our analysis is leptogenesis after sphaleron freeze-out, which leads to resonant dark matter production, evading thus the constraints on sterile neutrino dark matter from structure formation and x-ray searches. We identify the range of sterile neutrino properties that is consistent with all known constraints. We find a domain of parameters where the new particles can be found with present day experimental techniques, using upgrades to existing experimental facilities.

  6. Role of baryons in unified dark matter models

    International Nuclear Information System (INIS)

    Beca, L.M.G.; Avelino, P.P.; Carvalho, J.P. de M.; Martins, C.J.A.P.

    2003-01-01

    We discuss the importance of including baryons in analyses of unified dark matter scenarios, focusing on toy models involving a generalized Chaplygin gas. We determine observational constraints on this unified dark matter scenario coming from large-scale structure, type Ia supernovae and CMB data showing how this component can bring about a different behavior from the classical cold dark matter model with a cosmological constant and thus motivate further studies of this type of models. We also speculate on interesting new features which are likely to be important on nonlinear scales in this context

  7. Simultaneous Generation of WIMP Miracle-like Densities of Baryons and Dark Matter

    International Nuclear Information System (INIS)

    McDonald, John

    2012-01-01

    The observed density of dark matter is of the magnitude expected for a thermal relic weakly-interacting massive particle (WIMP). In addition, the observed baryon density is within an order of magnitude of the dark matter density. This suggests that the baryon density is physically related to a typical thermal relic WIMP dark matter density. We present a model which simultaneously generates thermal relic WIMP-like densities for both baryons and dark matter by modifying a large initial baryon asymmetry. Production of unstable scalars carrying baryon number at the LHC would be a clear signature of the model.

  8. Galactic optical cloaking of visible baryonic matter

    Science.gov (United States)

    Smolyaninov, Igor I.

    2018-05-01

    Three-dimensional gravitational cloaking is known to require exotic matter and energy sources, which makes it arguably physically unrealizable. On the other hand, typical astronomical observations are performed using one-dimensional paraxial line of sight geometries. We demonstrate that unidirectional line of sight gravitational cloaking does not require exotic matter, and it may occur in multiple natural astronomical scenarios that involve gravitational lensing. In particular, recently discovered double gravitational lens SDSSJ 0 9 4 6 +1 0 0 6 together with the Milky Way appear to form a natural paraxial cloak. A natural question to ask, then, is how much matter in the Universe may be hidden from view by such natural gravitational cloaks? It is estimated that the total volume hidden from an observer by gravitational cloaking may reach about 1% of the total volume of the visible Universe.

  9. Vorticity and Λ polarization in baryon rich matter

    Science.gov (United States)

    Baznat, Mircea; Gudima, Konstantin; Prokhorov, George; Sorin, Alexander; Teryaev, Oleg; Zakharov, Valentin

    2018-02-01

    The polarization of Λ hyperons due to axial chiral vortical effect is discussed. The effect is proportional to (strange) chemical potential and is pronounced at lower energies in baryon-rich matter. The polarization of ¯ has the same sihn and larger magnitude. The emergence of vortical structures is observed in kinetic QGSM models. The hydrodynamical helicity separation receives the contribution of longitudinal velocity and vorticity implying the quadrupole structure of the latter. The transition from the quark vortical effects to baryons in confined phase may be achieved by exploring the axial charge. At the hadronic level the polarization corresponds to the cores of quantized vortices in pionic superfluid. The chiral vortical effects may be also studied in the frmework of Wigner function establishing the relation to the thermodynamical approach to polarization.

  10. Theories relating baryon asymmetry and dark matter: a Mini review

    Directory of Open Access Journals (Sweden)

    Stefano eMorisi

    2014-01-01

    Full Text Available The nature of dark matter and the origin of the baryon asymmetry are two of the deepest mysteries of modern particle physics. In the absence of hints regarding a possible solution to these mysteries, many approaches have been developed to tackle them simultaneously { leading to very diverse and rich models}. We give a short review where we describe the general features of some of these models and an overview on the general problem. We also propose a diagrammatic notation to label the different models.

  11. Dark matter as a weakly coupled dark baryon

    Science.gov (United States)

    Mitridate, Andrea; Redi, Michele; Smirnov, Juri; Strumia, Alessandro

    2017-10-01

    Dark Matter might be an accidentally stable baryon of a new confining gauge interaction. We extend previous studies exploring the possibility that the DM is made of dark quarks heavier than the dark confinement scale. The resulting phenomenology contains new unusual elements: a two-stage DM cosmology (freeze-out followed by dark condensation), a large DM annihilation cross section through recombination of dark quarks (allowing to fit the positron excess). Light dark glue-balls are relatively long lived and give extra cosmological effects; DM itself can remain radioactive.

  12. Modified dark matter: Relating dark energy, dark matter and baryonic matter

    Science.gov (United States)

    Edmonds, Douglas; Farrah, Duncan; Minic, Djordje; Ng, Y. Jack; Takeuchi, Tatsu

    Modified dark matter (MDM) is a phenomenological model of dark matter, inspired by gravitational thermodynamics. For an accelerating universe with positive cosmological constant (Λ), such phenomenological considerations lead to the emergence of a critical acceleration parameter related to Λ. Such a critical acceleration is an effective phenomenological manifestation of MDM, and it is found in correlations between dark matter and baryonic matter in galaxy rotation curves. The resulting MDM mass profiles, which are sensitive to Λ, are consistent with observational data at both the galactic and cluster scales. In particular, the same critical acceleration appears both in the galactic and cluster data fits based on MDM. Furthermore, using some robust qualitative arguments, MDM appears to work well on cosmological scales, even though quantitative studies are still lacking. Finally, we comment on certain nonlocal aspects of the quanta of modified dark matter, which may lead to novel nonparticle phenomenology and which may explain why, so far, dark matter detection experiments have failed to detect dark matter particles.

  13. Challenges in QCD matter physics -The scientific programme of the Compressed Baryonic Matter experiment at FAIR

    Science.gov (United States)

    Ablyazimov, T.; Abuhoza, A.; Adak, R. P.; Adamczyk, M.; Agarwal, K.; Aggarwal, M. M.; Ahammed, Z.; Ahmad, F.; Ahmad, N.; Ahmad, S.; Akindinov, A.; Akishin, P.; Akishina, E.; Akishina, T.; Akishina, V.; Akram, A.; Al-Turany, M.; Alekseev, I.; Alexandrov, E.; Alexandrov, I.; Amar-Youcef, S.; Anđelić, M.; Andreeva, O.; Andrei, C.; Andronic, A.; Anisimov, Yu.; Appelshäuser, H.; Argintaru, D.; Atkin, E.; Avdeev, S.; Averbeck, R.; Azmi, M. D.; Baban, V.; Bach, M.; Badura, E.; Bähr, S.; Balog, T.; Balzer, M.; Bao, E.; Baranova, N.; Barczyk, T.; Bartoş, D.; Bashir, S.; Baszczyk, M.; Batenkov, O.; Baublis, V.; Baznat, M.; Becker, J.; Becker, K.-H.; Belogurov, S.; Belyakov, D.; Bendarouach, J.; Berceanu, I.; Bercuci, A.; Berdnikov, A.; Berdnikov, Y.; Berendes, R.; Berezin, G.; Bergmann, C.; Bertini, D.; Bertini, O.; Beşliu, C.; Bezshyyko, O.; Bhaduri, P. P.; Bhasin, A.; Bhati, A. K.; Bhattacharjee, B.; Bhattacharyya, A.; Bhattacharyya, T. K.; Biswas, S.; Blank, T.; Blau, D.; Blinov, V.; Blume, C.; Bocharov, Yu.; Book, J.; Breitner, T.; Brüning, U.; Brzychczyk, J.; Bubak, A.; Büsching, H.; Bus, T.; Butuzov, V.; Bychkov, A.; Byszuk, A.; Cai, Xu; Cãlin, M.; Cao, Ping; Caragheorgheopol, G.; Carević, I.; Cătănescu, V.; Chakrabarti, A.; Chattopadhyay, S.; Chaus, A.; Chen, Hongfang; Chen, LuYao; Cheng, Jianping; Chepurnov, V.; Cherif, H.; Chernogorov, A.; Ciobanu, M. I.; Claus, G.; Constantin, F.; Csanád, M.; D'Ascenzo, N.; Das, Supriya; Das, Susovan; de Cuveland, J.; Debnath, B.; Dementiev, D.; Deng, Wendi; Deng, Zhi; Deppe, H.; Deppner, I.; Derenovskaya, O.; Deveaux, C. A.; Deveaux, M.; Dey, K.; Dey, M.; Dillenseger, P.; Dobyrn, V.; Doering, D.; Dong, Sheng; Dorokhov, A.; Dreschmann, M.; Drozd, A.; Dubey, A. K.; Dubnichka, S.; Dubnichkova, Z.; Dürr, M.; Dutka, L.; Dželalija, M.; Elsha, V. V.; Emschermann, D.; Engel, H.; Eremin, V.; Eşanu, T.; Eschke, J.; Eschweiler, D.; Fan, Huanhuan; Fan, Xingming; Farooq, M.; Fateev, O.; Feng, Shengqin; Figuli, S. P. D.; Filozova, I.; Finogeev, D.; Fischer, P.; Flemming, H.; Förtsch, J.; Frankenfeld, U.; Friese, V.; Friske, E.; Fröhlich, I.; Frühauf, J.; Gajda, J.; Galatyuk, T.; Gangopadhyay, G.; García Chávez, C.; Gebelein, J.; Ghosh, P.; Ghosh, S. K.; Gläßel, S.; Goffe, M.; Golinka-Bezshyyko, L.; Golovatyuk, V.; Golovnya, S.; Golovtsov, V.; Golubeva, M.; Golubkov, D.; Gómez Ramírez, A.; Gorbunov, S.; Gorokhov, S.; Gottschalk, D.; Gryboś, P.; Grzeszczuk, A.; Guber, F.; Gudima, K.; Gumiński, M.; Gupta, A.; Gusakov, Yu.; Han, Dong; Hartmann, H.; He, Shue; Hehner, J.; Heine, N.; Herghelegiu, A.; Herrmann, N.; Heß, B.; Heuser, J. M.; Himmi, A.; Höhne, C.; Holzmann, R.; Hu, Dongdong; Huang, Guangming; Huang, Xinjie; Hutter, D.; Ierusalimov, A.; Ilgenfritz, E.-M.; Irfan, M.; Ivanischev, D.; Ivanov, M.; Ivanov, P.; Ivanov, Valery; Ivanov, Victor; Ivanov, Vladimir; Ivashkin, A.; Jaaskelainen, K.; Jahan, H.; Jain, V.; Jakovlev, V.; Janson, T.; Jiang, Di; Jipa, A.; Kadenko, I.; Kähler, P.; Kämpfer, B.; Kalinin, V.; Kallunkathariyil, J.; Kampert, K.-H.; Kaptur, E.; Karabowicz, R.; Karavichev, O.; Karavicheva, T.; Karmanov, D.; Karnaukhov, V.; Karpechev, E.; Kasiński, K.; Kasprowicz, G.; Kaur, M.; Kazantsev, A.; Kebschull, U.; Kekelidze, G.; Khan, M. M.; Khan, S. A.; Khanzadeev, A.; Khasanov, F.; Khvorostukhin, A.; Kirakosyan, V.; Kirejczyk, M.; Kiryakov, A.; Kiš, M.; Kisel, I.; Kisel, P.; Kiselev, S.; Kiss, T.; Klaus, P.; Kłeczek, R.; Klein-Bösing, Ch.; Kleipa, V.; Klochkov, V.; Kmon, P.; Koch, K.; Kochenda, L.; Koczoń, P.; Koenig, W.; Kohn, M.; Kolb, B. W.; Kolosova, A.; Komkov, B.; Korolev, M.; Korolko, I.; Kotte, R.; Kovalchuk, A.; Kowalski, S.; Koziel, M.; Kozlov, G.; Kozlov, V.; Kramarenko, V.; Kravtsov, P.; Krebs, E.; Kreidl, C.; Kres, I.; Kresan, D.; Kretschmar, G.; Krieger, M.; Kryanev, A. V.; Kryshen, E.; Kuc, M.; Kucewicz, W.; Kucher, V.; Kudin, L.; Kugler, A.; Kumar, Ajit; Kumar, Ashwini; Kumar, L.; Kunkel, J.; Kurepin, A.; Kurepin, N.; Kurilkin, A.; Kurilkin, P.; Kushpil, V.; Kuznetsov, S.; Kyva, V.; Ladygin, V.; Lara, C.; Larionov, P.; Laso García, A.; Lavrik, E.; Lazanu, I.; Lebedev, A.; Lebedev, S.; Lebedeva, E.; Lehnert, J.; Lehrbach, J.; Leifels, Y.; Lemke, F.; Li, Cheng; Li, Qiyan; Li, Xin; Li, Yuanjing; Lindenstruth, V.; Linnik, B.; Liu, Feng; Lobanov, I.; Lobanova, E.; Löchner, S.; Loizeau, P.-A.; Lone, S. A.; Lucio Martínez, J. A.; Luo, Xiaofeng; Lymanets, A.; Lyu, Pengfei; Maevskaya, A.; Mahajan, S.; Mahapatra, D. P.; Mahmoud, T.; Maj, P.; Majka, Z.; Malakhov, A.; Malankin, E.; Malkevich, D.; Malyatina, O.; Malygina, H.; Mandal, M. M.; Mandal, S.; Manko, V.; Manz, S.; Marin Garcia, A. M.; Markert, J.; Masciocchi, S.; Matulewicz, T.; Meder, L.; Merkin, M.; Mialkovski, V.; Michel, J.; Miftakhov, N.; Mik, L.; Mikhailov, K.; Mikhaylov, V.; Milanović, B.; Militsija, V.; Miskowiec, D.; Momot, I.; Morhardt, T.; Morozov, S.; Müller, W. F. J.; Müntz, C.; Mukherjee, S.; Muñoz Castillo, C. E.; Murin, Yu.; Najman, R.; Nandi, C.; Nandy, E.; Naumann, L.; Nayak, T.; Nedosekin, A.; Negi, V. S.; Niebur, W.; Nikulin, V.; Normanov, D.; Oancea, A.; Oh, Kunsu; Onishchuk, Yu.; Ososkov, G.; Otfinowski, P.; Ovcharenko, E.; Pal, S.; Panasenko, I.; Panda, N. R.; Parzhitskiy, S.; Patel, V.; Pauly, C.; Penschuck, M.; Peshekhonov, D.; Peshekhonov, V.; Petráček, V.; Petri, M.; Petriş, M.; Petrovici, A.; Petrovici, M.; Petrovskiy, A.; Petukhov, O.; Pfeifer, D.; Piasecki, K.; Pieper, J.; Pietraszko, J.; Płaneta, R.; Plotnikov, V.; Plujko, V.; Pluta, J.; Pop, A.; Pospisil, V.; Poźniak, K.; Prakash, A.; Prasad, S. K.; Prokudin, M.; Pshenichnov, I.; Pugach, M.; Pugatch, V.; Querchfeld, S.; Rabtsun, S.; Radulescu, L.; Raha, S.; Rami, F.; Raniwala, R.; Raniwala, S.; Raportirenko, A.; Rautenberg, J.; Rauza, J.; Ray, R.; Razin, S.; Reichelt, P.; Reinecke, S.; Reinefeld, A.; Reshetin, A.; Ristea, C.; Ristea, O.; Rodriguez Rodriguez, A.; Roether, F.; Romaniuk, R.; Rost, A.; Rostchin, E.; Rostovtseva, I.; Roy, Amitava; Roy, Ankhi; Rożynek, J.; Ryabov, Yu.; Sadovsky, A.; Sahoo, R.; Sahu, P. K.; Sahu, S. K.; Saini, J.; Samanta, S.; Sambyal, S. S.; Samsonov, V.; Sánchez Rosado, J.; Sander, O.; Sarangi, S.; Satława, T.; Sau, S.; Saveliev, V.; Schatral, S.; Schiaua, C.; Schintke, F.; Schmidt, C. J.; Schmidt, H. R.; Schmidt, K.; Scholten, J.; Schweda, K.; Seck, F.; Seddiki, S.; Selyuzhenkov, I.; Semennikov, A.; Senger, A.; Senger, P.; Shabanov, A.; Shabunov, A.; Shao, Ming; Sheremetiev, A. D.; Shi, Shusu; Shumeiko, N.; Shumikhin, V.; Sibiryak, I.; Sikora, B.; Simakov, A.; Simon, C.; Simons, C.; Singaraju, R. N.; Singh, A. K.; Singh, B. K.; Singh, C. P.; Singhal, V.; Singla, M.; Sitzmann, P.; Siwek-Wilczyńska, K.; Škoda, L.; Skwira-Chalot, I.; Som, I.; Song, Guofeng; Song, Jihye; Sosin, Z.; Soyk, D.; Staszel, P.; Strikhanov, M.; Strohauer, S.; Stroth, J.; Sturm, C.; Sultanov, R.; Sun, Yongjie; Svirida, D.; Svoboda, O.; Szabó, A.; Szczygieł, R.; Talukdar, R.; Tang, Zebo; Tanha, M.; Tarasiuk, J.; Tarassenkova, O.; Târzilă, M.-G.; Teklishyn, M.; Tischler, T.; Tlustý, P.; Tölyhi, T.; Toia, A.; Topil'skaya, N.; Träger, M.; Tripathy, S.; Tsakov, I.; Tsyupa, Yu.; Turowiecki, A.; Tuturas, N. G.; Uhlig, F.; Usenko, E.; Valin, I.; Varga, D.; Vassiliev, I.; Vasylyev, O.; Verbitskaya, E.; Verhoeven, W.; Veshikov, A.; Visinka, R.; Viyogi, Y. P.; Volkov, S.; Volochniuk, A.; Vorobiev, A.; Voronin, Aleksey; Voronin, Alexander; Vovchenko, V.; Vznuzdaev, M.; Wang, Dong; Wang, Xi-Wei; Wang, Yaping; Wang, Yi; Weber, M.; Wendisch, C.; Wessels, J. P.; Wiebusch, M.; Wiechula, J.; Wielanek, D.; Wieloch, A.; Wilms, A.; Winckler, N.; Winter, M.; Wiśniewski, K.; Wolf, Gy.; Won, Sanguk; Wu, Ke-Jun; Wüstenfeld, J.; Xiang, Changzhou; Xu, Nu; Yang, Junfeng; Yang, Rongxing; Yin, Zhongbao; Yoo, In-Kwon; Yuldashev, B.; Yushmanov, I.; Zabołotny, W.; Zaitsev, Yu.; Zamiatin, N. I.; Zanevsky, Yu.; Zhalov, M.; Zhang, Yifei; Zhang, Yu; Zhao, Lei; Zheng, Jiajun; Zheng, Sheng; Zhou, Daicui; Zhou, Jing; Zhu, Xianglei; Zinchenko, A.; Zipper, W.; Żoładź, M.; Zrelov, P.; Zryuev, V.; Zumbruch, P.; Zyzak, M.

    2017-03-01

    Substantial experimental and theoretical efforts worldwide are devoted to explore the phase diagram of strongly interacting matter. At LHC and top RHIC energies, QCD matter is studied at very high temperatures and nearly vanishing net-baryon densities. There is evidence that a Quark-Gluon-Plasma (QGP) was created at experiments at RHIC and LHC. The transition from the QGP back to the hadron gas is found to be a smooth cross over. For larger net-baryon densities and lower temperatures, it is expected that the QCD phase diagram exhibits a rich structure, such as a first-order phase transition between hadronic and partonic matter which terminates in a critical point, or exotic phases like quarkyonic matter. The discovery of these landmarks would be a breakthrough in our understanding of the strong interaction and is therefore in the focus of various high-energy heavy-ion research programs. The Compressed Baryonic Matter (CBM) experiment at FAIR will play a unique role in the exploration of the QCD phase diagram in the region of high net-baryon densities, because it is designed to run at unprecedented interaction rates. High-rate operation is the key prerequisite for high-precision measurements of multi-differential observables and of rare diagnostic probes which are sensitive to the dense phase of the nuclear fireball. The goal of the CBM experiment at SIS100 (√{s_{NN}}= 2.7-4.9 GeV) is to discover fundamental properties of QCD matter: the phase structure at large baryon-chemical potentials ( μ_B > 500 MeV), effects of chiral symmetry, and the equation of state at high density as it is expected to occur in the core of neutron stars. In this article, we review the motivation for and the physics programme of CBM, including activities before the start of data taking in 2024, in the context of the worldwide efforts to explore high-density QCD matter.

  14. The baryonic Tully-Fisher relation and its implication for dark matter halos

    NARCIS (Netherlands)

    Trachternach, C.; de Blok, W. J. G.; McGaugh, S. S.; van der Hulst, J. M.; Dettmar, R. -J.

    2009-01-01

    Context. The baryonic Tully-Fisher relation (BTF) is a fundamental relation between baryonic mass and maximum rotation velocity. It can be used to estimate distances, as well as to constrain the properties of dark matter and its relation with the visible matter. Aims. In this paper, we explore if

  15. The Angular Momentum of Baryons and Dark Matter Halos Revisited

    Science.gov (United States)

    Kimm, Taysun; Devriendt, Julien; Slyz, Adrianne; Pichon, Christophe; Kassin, Susan A.; Dubois, Yohan

    2011-01-01

    Recent theoretical studies have shown that galaxies at high redshift are fed by cold, dense gas filaments, suggesting angular momentum transport by gas differs from that by dark matter. Revisiting this issue using high-resolution cosmological hydrodynamics simulations with adaptive-mesh refinement (AMR), we find that at the time of accretion, gas and dark matter do carry a similar amount of specific angular momentum, but that it is systematically higher than that of the dark matter halo as a whole. At high redshift, freshly accreted gas rapidly streams into the central region of the halo, directly depositing this large amount of angular momentum within a sphere of radius r = 0.1R(sub vir). In contrast, dark matter particles pass through the central region unscathed, and a fraction of them ends up populating the outer regions of the halo (r/R(sub vir) > 0.1), redistributing angular momentum in the process. As a result, large-scale motions of the cosmic web have to be considered as the origin of gas angular momentum rather than its virialised dark matter halo host. This generic result holds for halos of all masses at all redshifts, as radiative cooling ensures that a significant fraction of baryons remain trapped at the centre of the halos. Despite this injection of angular momentum enriched gas, we predict an amount for stellar discs which is in fair agreement with observations at z=0. This arises because the total specific angular momentum of the baryons (gas and stars) remains close to that of dark matter halos. Indeed, our simulations indicate that any differential loss of angular momentum amplitude between the two components is minor even though dark matter halos continuously lose between half and two-thirds of their specific angular momentum modulus as they evolve. In light of our results, a substantial revision of the standard theory of disc formation seems to be required. We propose a new scenario where gas efficiently carries the angular momentum generated

  16. The diverse density profiles of galaxy clusters with self-interacting dark matter plus baryons

    Science.gov (United States)

    Robertson, Andrew; Massey, Richard; Eke, Vincent; Tulin, Sean; Yu, Hai-Bo; Bahé, Yannick; Barnes, David J.; Bower, Richard G.; Crain, Robert A.; Dalla Vecchia, Claudio; Kay, Scott T.; Schaller, Matthieu; Schaye, Joop

    2018-05-01

    We present the first simulated galaxy clusters (M200 > 1014 M⊙) with both self-interacting dark matter (SIDM) and baryonic physics. They exhibit a greater diversity in both dark matter and stellar density profiles than their counterparts in simulations with collisionless dark matter (CDM), which is generated by the complex interplay between dark matter self-interactions and baryonic physics. Despite variations in formation history, we demonstrate that analytical Jeans modelling predicts the SIDM density profiles remarkably well, and the diverse properties of the haloes can be understood in terms of their different final baryon distributions.

  17. Entropy, baryon asymmetry and dark matter from heavy neutrino decays

    International Nuclear Information System (INIS)

    Buchmueller, W.; Schmitz, K.; Vertongen, G.

    2011-01-01

    The origin of the hot phase of the early universe remains so far an unsolved puzzle. A viable option is entropy production through the decays of heavy Majorana neutrinos whose lifetimes determine the initial temperature. We show that baryogenesis and the production of dark matter are natural by-products of this mechanism. As is well known, the cosmological baryon asymmetry can be accounted for by leptogenesis for characteristic neutrino mass parameters. We find that thermal gravitino production then automatically yields the observed amount of dark matter, for the gravitino as the lightest superparticle and typical gluino masses. As an example, we consider the production of heavy Majorana neutrinos in the course of tachyonic preheating associated with spontaneous B-L breaking. A quantitative analysis leads to constraints on the superparticle masses in terms of neutrino masses: For a light neutrino mass of 10 -5 eV the gravitino mass can be as small as 200 MeV, whereas a lower neutrino mass bound of 0.01 eV implies a lower bound of 9 GeV on the gravitino mass. The measurement of a light neutrino mass of 0.1 eV would rule out heavy neutrino decays as the origin of entropy, visible and dark matter.

  18. Entropy, baryon asymmetry and dark matter from heavy neutrino decays

    Energy Technology Data Exchange (ETDEWEB)

    Buchmueller, W.; Schmitz, K.; Vertongen, G.

    2011-04-15

    The origin of the hot phase of the early universe remains so far an unsolved puzzle. A viable option is entropy production through the decays of heavy Majorana neutrinos whose lifetimes determine the initial temperature. We show that baryogenesis and the production of dark matter are natural by-products of this mechanism. As is well known, the cosmological baryon asymmetry can be accounted for by lepto- genesis for characteristic neutrino mass parameters. We nd that thermal gravitino production then automatically yields the observed amount of dark matter, for the gravitino as the lightest superparticle and typical gluino masses. As an example, we consider the production of heavy Majorana neutrinos in the course of tachyonic preheating associated with spontaneous B-L breaking. A quantitative analysis leads to contraints on the superparticle masses in terms of neutrino masses: For a light neutrino mass of 10{sup -5} eV the gravitino mass can be as small as 200 MeV, whereas a lower neutrino mass bound of 0.01 eV implies a lower bound of 9 GeV on the gravitino mass. The measurement of a light neutrino mass of 0.1 eV would rule out heavy neutrino decays as the origin of entropy, visible and dark matter. (orig.)

  19. Dilepton as a signature for the baryon-rich quark-gluon matter

    International Nuclear Information System (INIS)

    Zejun He; Jiaju Zhang

    1995-01-01

    From the full stopping scenario, we study dilepton production in a baryon rich quark-gluon fireball on the basis of a relativistic hydrodynamic model, and find that with increasing initial baryon density a characteristic valley and a subsequent peak, which more uniquely signal the formation of the baryon-rich quark-gluon matter, appear in the total dilepton yield. Such characteristics can be tested in future experiments at CERN and Brookhaven. (author). Letter-to-the-editor

  20. Baryonic forces and hyperons in nuclear matter from SU(3) chiral effective field theory

    Energy Technology Data Exchange (ETDEWEB)

    Petschauer, Stefan Karl

    2016-02-12

    In this work the baryon-baryon interaction is studied at next-to-leading order in SU(3) chiral effective field theory and applied to hyperon-nucleon scattering. The properties of hyperons in isospin-symmetric as well as asymmetric nuclear matter are calculated within the Bruecker-Hartree-Fock formalism. Moreover, the leading three-baryon interaction is derived and its low-energy constants are estimated from decuplet intermediate states. We conclude, that chiral effective field theory is a well-suited tool to describe the baryonic forces.

  1. Brane-induced Skyrmion on S3: Baryonic matter in holographic QCD

    International Nuclear Information System (INIS)

    Nawa, Kanabu; Suganuma, Hideo; Kojo, Toru

    2009-01-01

    We study baryonic matter in holographic QCD with D4/D8/D8 multi-D brane system in type IIA superstring theory. The baryon is described as the 'brane-induced Skyrmion', which is a topologically nontrivial chiral soliton in the four-dimensional meson effective action induced by holographic QCD. We employ the ''truncated-resonance model'' approach for the baryon analysis, including pion and ρ meson fields below the ultraviolet cutoff scale M KK ∼1 GeV, to keep the holographic duality with QCD. We describe the baryonic matter in large N c as single brane-induced Skyrmion on the three-dimensional closed manifold S 3 with finite radius R. The interactions between baryons are simulated by the curvature of the closed manifold S 3 , and the decrease of the size of S 3 represents the increase of the total baryon-number density in the medium in this modeling. We investigate the energy density, the field configuration, the mass and the root-mean-square radius of single baryon on S 3 as the function of its radius R. We find a new picture of 'pion dominance' near the critical density in the baryonic matter, where all the (axial) vector meson fields disappear and only the pion fields survive. We also find the swelling phenomena of the baryons as the precursor of the deconfinement, and propose the mechanism of the swelling in the general context of QCD. The properties of the deconfinement and the chiral symmetry restoration in the baryonic matter are examined by taking the proper order parameters. We also compare our truncated-resonance model with another instanton description of the baryon in holographic QCD, considering the role of cutoff scale M KK .

  2. Challenges in QCD matter physics. The scientific programme of the Compressed Baryonic Matter experiment at FAIR

    Energy Technology Data Exchange (ETDEWEB)

    Ablyazimov, T. [Joint Institute for Nuclear Research (JINR-LIT), Dubna (Russian Federation). Lab. of Information Technologies; Abuhoza, A. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH (GSI), Darmstadt (Germany); Adak, R.P. [Bose Institute, Kolkata (India). Dept. of Physics; and others

    2017-03-15

    Substantial experimental and theoretical efforts worldwide are devoted to explore the phase diagram of strongly interacting matter. At LHC and top RHIC energies, QCD matter is studied at very high temperatures and nearly vanishing net-baryon densities. There is evidence that a Quark-Gluon-Plasma (QGP) was created at experiments at RHIC and LHC. The transition from the QGP back to the hadron gas is found to be a smooth cross over. For larger net-baryon densities and lower temperatures, it is expected that the QCD phase diagram exhibits a rich structure, such as a first-order phase transition between hadronic and partonic matter which terminates in a critical point, or exotic phases like quarkyonic matter. The discovery of these landmarks would be a breakthrough in our understanding of the strong interaction and is therefore in the focus of various high-energy heavy-ion research programs. The Compressed Baryonic Matter (CBM) experiment at FAIR will play a unique role in the exploration of the QCD phase diagram in the region of high net-baryon densities, because it is designed to run at unprecedented interaction rates. High-rate operation is the key prerequisite for high-precision measurements of multi-differential observables and of rare diagnostic probes which are sensitive to the dense phase of the nuclear fireball. The goal of the CBM experiment at SIS100 (√(s{sub NN}) = 2.7-4.9 GeV) is to discover fundamental properties of QCD matter: the phase structure at large baryon-chemical potentials (μ{sub B} > 500 MeV), effects of chiral symmetry, and the equation of state at high density as it is expected to occur in the core of neutron stars. In this article, we review the motivation for and the physics programme of CBM, including activities before the start of data taking in 2024, in the context of the worldwide efforts to explore high-density QCD matter. (orig.)

  3. Challenges in QCD matter physics. The scientific programme of the Compressed Baryonic Matter experiment at FAIR

    International Nuclear Information System (INIS)

    Ablyazimov, T.; Adak, R.P.

    2017-01-01

    Substantial experimental and theoretical efforts worldwide are devoted to explore the phase diagram of strongly interacting matter. At LHC and top RHIC energies, QCD matter is studied at very high temperatures and nearly vanishing net-baryon densities. There is evidence that a Quark-Gluon-Plasma (QGP) was created at experiments at RHIC and LHC. The transition from the QGP back to the hadron gas is found to be a smooth cross over. For larger net-baryon densities and lower temperatures, it is expected that the QCD phase diagram exhibits a rich structure, such as a first-order phase transition between hadronic and partonic matter which terminates in a critical point, or exotic phases like quarkyonic matter. The discovery of these landmarks would be a breakthrough in our understanding of the strong interaction and is therefore in the focus of various high-energy heavy-ion research programs. The Compressed Baryonic Matter (CBM) experiment at FAIR will play a unique role in the exploration of the QCD phase diagram in the region of high net-baryon densities, because it is designed to run at unprecedented interaction rates. High-rate operation is the key prerequisite for high-precision measurements of multi-differential observables and of rare diagnostic probes which are sensitive to the dense phase of the nuclear fireball. The goal of the CBM experiment at SIS100 (√(s_N_N) = 2.7-4.9 GeV) is to discover fundamental properties of QCD matter: the phase structure at large baryon-chemical potentials (μ_B > 500 MeV), effects of chiral symmetry, and the equation of state at high density as it is expected to occur in the core of neutron stars. In this article, we review the motivation for and the physics programme of CBM, including activities before the start of data taking in 2024, in the context of the worldwide efforts to explore high-density QCD matter. (orig.)

  4. Simultaneous generation of WIMP miracle-like densities of baryons and dark matter

    International Nuclear Information System (INIS)

    McDonald, John

    2011-01-01

    The observed density of dark matter is of the magnitude expected for a thermal relic weakly-interacting massive particle (WIMP). In addition, the observed baryon density is within an order of magnitude of the dark matter density. This suggests that the baryon density is physically related to a typical thermal relic WIMP dark matter density. We present a model which simultaneously generates thermal relic WIMP-like densities for both baryons and dark matter by modifying a large initial baryon asymmetry. Dark matter is due to O(100) GeV gauge singlet scalars produced in the annihilation of the O(TeV) colored scalars which are responsible for the final thermal WIMP-like baryon asymmetry. The requirement of no baryon washout implies that there are two gauge singlet scalars. The low-temperature transfer of the asymmetry to conventional baryons can be understood if the long-lived O(TeV) colored scalars have large hypercharge, |Y|>4/3. Production of such scalars at the LHC would be a clear signature of the model.

  5. Helioseismology with long-range dark matter-baryon interactions

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, Ilídio [Centro Multidisciplinar de Astrofísica, Instituto Superior Técnico, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Panci, Paolo [CP3-Origins and DIAS, University of Southern Denmark, DK-5230 Odense (Denmark); Silk, Joseph, E-mail: ilidio.lopes@tecnico.ulisboa.pt, E-mail: panci@iap.fr, E-mail: silk@astro.ox.ac.uk [Institut d' Astrophysique, UMR 7095 CNRS, Université Pierre et Marie Curie, 98bis Blvd Arago, F-75014 Paris (France)

    2014-11-10

    Assuming the existence of a primordial asymmetry in the dark sector, we study how long-range dark matter (DM)-baryon interactions, induced by the kinetic mixing of a new U(1) gauge boson and a photon, affect the evolution of the Sun and, in turn, the sound speed the profile obtained from helioseismology. Thanks to the explicit dependence on the exchanged momenta in the differential cross section (Rutherford-like scattering), we find that DM particles with a mass of ∼10 GeV, kinetic mixing parameter of the order of 10{sup –9}, and a mediator with a mass smaller than a few MeV improve the agreement between the best solar model and the helioseismic data without being excluded by direct detection experiments. In particular, the LUX detector will soon be able to either constrain or confirm our best-fit solar model in the presence of a dark sector with long-range interactions that reconcile helioseismology with thermal neutrino results.

  6. Dark and visible matter in a baryon-symmetric universe via the Affleck-Dine mechanism

    International Nuclear Information System (INIS)

    Bell, Nicole F.; Petraki, Kalliopi; Volkas, Raymond R.; Shoemaker, Ian M.

    2011-01-01

    The similarity of the visible and dark matter abundances indicates that they may originate via the same mechanism. If both the dark and visible matter are charged under a generalized baryon number, then the asymmetry of the visible sector may be compensated by an asymmetry in the dark sector. We show how the separation of the baryonic and the -antibaryonic charge can originate in the vacuum, via the Affleck-Dine mechanism, due to the breaking of a symmetry orthogonal to the baryon number. Symmetry restoration in the current epoch guarantees the individual stability of the two sectors.

  7. Dark matter-baryon segregation in the nonlinear evolution of coupled dark energy models

    International Nuclear Information System (INIS)

    Mainini, Roberto

    2005-01-01

    The growth and virialization of spherical top-hat fluctuations, in coupled dark energy models, causes segregation between dark matter (DM) and baryons, as the gravitational infall into the potential well proceeds more slowly for the baryons than for DM. As a consequence, after attaining their turnaround and before full virialization, halos have outer layers rich of baryons. Accordingly, a natural ambiguity exists on the definition of the virial density contrast. In fact, when the outer baryon layers infall onto the DM-richer core, they carry with them DM materials outside the original fluctuation; hence, no time exists when all materials originally belonging to the fluctuation--and only they--have virialized. Baryon-DM segregation can have various astrophysical consequences on different length scales. The smallest halos may loose up to 50% of the original baryonic contents and become hardly visible. Subhalos in cluster-size halos may loose much baryonic materials, which could then be observed as intracluster light. Isolated halos, in general, can be expected to have a baryon component richer than the cosmological proportions, due to the cosmic enrichement of baryons lost in small halo encounters

  8. The Baryonic and Dark Matter Distributions in Abell 401

    Science.gov (United States)

    Nevalainen, J.; Markevitch, M.; Forman, W.

    1999-11-01

    We combine spatially resolved ASCA temperature data with ROSAT imaging data to constrain the total mass distribution in the cluster A401, assuming that the cluster is in hydrostatic equilibrium, but without the assumption of gas isothermality. We obtain a total mass within the X-ray core (290 h-150 kpc) of 1.2+0.1-0.5×1014 h-150 Msolar at the 90% confidence level, 1.3 times larger than the isothermal estimate. The total mass within r500 (1.7 h-150 Mpc) is M500=0.9+0.3-0.2×1015 h-150 Msolar at 90% confidence, in agreement with the optical virial mass estimate, and 1.2 times smaller than the isothermal estimate. Our M500 value is 1.7 times smaller than that estimated using the mass-temperature scaling law predicted by simulations. The best-fit dark matter density profile scales as r-3.1 at large radii, which is consistent with the Navarro, Frenk & White (NFW) ``universal profile'' as well as the King profile of the galaxy density in A401. From the imaging data, the gas density profile is shallower than the dark matter profile, scaling as r-2.1 at large radii, leading to a monotonically increasing gas mass fraction with radius. Within r500 the gas mass fraction reaches a value of fgas=0.21+0.06-0.05 h-3/250 (90% confidence errors). Assuming that fgas (plus an estimate of the stellar mass) is the universal value of the baryon fraction, we estimate the 90% confidence upper limit of the cosmological matter density to be ΩmEinstein-deSitter universe. Even though the NFW dark matter density profile is statistically consistent with the temperature data, its central temperature cusp would lead to convective instability at the center, because the gas density does not have a corresponding peak. One way to reconcile a cusp-shaped total mass profile with the observed gas density profile, regardless of the temperature data, is to introduce a significant nonthermal pressure in the center. Such a pressure must satisfy the hydrostatic equilibrium condition without inducing

  9. Strangeness as a probe to baryon-rich QCD matter at NICA

    Energy Technology Data Exchange (ETDEWEB)

    Fukushima, Kenji [The University of Tokyo, Department of Physics, Bunkyo-ku, Tokyo (Japan)

    2016-08-15

    We elucidate a prospect of strangeness fluctuation measurements in the heavy-ion collision at NICA energies. The strangeness fluctuation is sensitive to quark deconfinement. At the same time strangeness has a strong correlation with the baryon number under the condition of vanishing net strangeness, which leads to an enhancement of Λ{sup 0}, Ξ{sup 0}, Ξ{sup -}, and K{sup +} at high baryon density. The baryon density is maximized around the NICA energies, and strangeness should be an ideal probe to investigate quark deconfinement phenomena of baryon-rich QCD matter created at NICA. We also utilize the hadron resonance gas model to estimate a mixed fluctuation of strangeness and baryon number. (orig.)

  10. The variation of the baryon-to-photon ratio during different cosmological epochs due to decay and annihilation of dark matter

    International Nuclear Information System (INIS)

    Zavarygin, E O; Ivanchik, A V

    2015-01-01

    An influence of annihilation and decay of the dark matter particles on the baryon-to-photon ratio has been studied for different cosmological epochs. We consider the different parameter values of the dark matter particles such as mass, annihilation cross section, lifetime and so on. The obtained results are compared with the data which come from the Big Bang nucleosynthesis calculation and from the analysis of the anisotropy of the cosmic microwave background radiation. It has been shown that the modern value of the dark matter density Ω CDM = 0.26 is enough to provide the variation of the baryon-to-photon ratio up to Δη/η ∼ 0.01÷1 for decay of the dark matter particles, but it also leads to an excess of the diffuse gamma ray background. We use the observational data on the diffuse gamma ray background in order to determine our constraints on the model of the dark matter particle decay and on the corresponding variation of the baryon-to-photon ratio: Δη/η ≲ 10 -5 . It has been shown that the variation of the baryon-to-photon ratio caused by the annihilation of the dark matter particles is negligible during the cosmological epochs from Big Bang nucleosynthesis to the present epoch. (paper)

  11. Massive graviton dark matter with environment dependent mass: A natural explanation of the dark matter-baryon ratio

    Science.gov (United States)

    Aoki, Katsuki; Mukohyama, Shinji

    2017-11-01

    We propose a scenario that can naturally explain the observed dark matter-baryon ratio in the context of bimetric theory with a chameleon field. We introduce two additional gravitational degrees of freedom, the massive graviton and the chameleon field, corresponding to dark matter and dark energy, respectively. The chameleon field is assumed to be nonminimally coupled to dark matter, i.e., the massive graviton, through the graviton mass terms. We find that the dark matter-baryon ratio is dynamically adjusted to the observed value due to the energy transfer by the chameleon field. As a result, the model can explain the observed dark matter-baryon ratio independently from the initial abundance of them.

  12. Quark seesaw mechanism, dark U (1 ) symmetry, and the baryon-dark matter coincidence

    Science.gov (United States)

    Gu, Pei-Hong; Mohapatra, Rabindra N.

    2017-09-01

    We attempt to understand the baryon-dark matter coincidence problem within the quark seesaw extension of the standard model where parity invariance is used to solve the strong C P problem. The S U (2 )L×S U (2 )R×U (1 )B -L gauge symmetry of this model is extended by a dark U (1 )X group plus inclusion of a heavy neutral vector-like fermion χL ,R charged under the dark group which plays the role of dark matter. All fermions are Dirac type in this model. Decay of heavy scalars charged under U (1 )X leads to simultaneous asymmetry generation of the dark matter and baryons after sphaleron effects are included. The U (1 )X group not only helps to stabilize the dark matter but also helps in the elimination of the symmetric part of the dark matter via χ -χ ¯ annihilation. For dark matter mass near the proton mass, it explains why the baryon and dark matter abundances are of similar magnitude (the baryon-dark matter coincidence problem). This model is testable in low threshold (sub-keV) direct dark matter search experiments.

  13. Diffusion constant in hot and dense hadronic matter. A hadro-molecular-dynamic calculation

    International Nuclear Information System (INIS)

    Sasaki, N.; Miyamura, O.; Muroya, S.; Nonaka, C.

    2002-01-01

    We evaluate baryon/charge diffusion constant of dense and hot hadronic matter based on the molecular dynamical method by using a hadronic collision generator which describes nuclear collisions at energies 10 1-2 GeV/A and satisfies detailed balance at low temperatures (T ≤ 200 MeV). For the hot and dense hadronic matter of the temperature range, T = 100 - 200 MeV and baryon number density, n B =0.16 fm -3 - 0.32 fm -3 , charge diffusion constant D gradually increases from 0.5 fmc to 2 fmc with temperature and is almost independent of baryon number density. Based on the obtained diffusion constant we make simple discussions on the diffusion of charge fluctuation in ultrarelativistic nuclear collisions. (author)

  14. Baryon symmetric big-bang cosmology. [matter-antimatter symmetry

    Science.gov (United States)

    Stecker, F. W.

    1978-01-01

    The framework of baryon-symmetric big-bang cosmology offers the greatest potential for deducing the evolution of the universe as a consequence of physical laws and processes with the minimum number of arbitrary assumptions as to initial conditions in the big-bang. In addition, it offers the possibility of explaining the photon-baryon ratio in the universe and how galaxies and galaxy clusters are formed, and also provides the only acceptable explanation at present for the origin of the cosmic gamma ray background radiation.

  15. Constraining strong baryon-dark-matter interactions with primordial nucleosynthesis and cosmic rays

    International Nuclear Information System (INIS)

    Cyburt, Richard H.; Fields, Brian D.; Pavlidou, Vasiliki; Wandelt, Benjamin

    2002-01-01

    Self-interacting dark matter (SIDM) was introduced by Spergel and Steinhardt to address possible discrepancies between collisionless dark matter simulations and observations on scales of less than 1 Mpc. We examine the case in which dark matter particles not only have strong self-interactions but also have strong interactions with baryons. The presence of such interactions will have direct implications for nuclear and particle astrophysics. Among these are a change in the predicted abundances from big bang nucleosynthesis (BBN) and the flux of γ rays produced by the decay of neutral pions which originate in collisions between dark matter and galactic cosmic rays (CR). From these effects we constrain the strength of the baryon-dark-matter interactions through the ratio of baryon-dark-matter interaction cross section to dark matter mass, s. We find that BBN places a weak upper limit on this ratio (less-or-similar sign)10 8 cm 2 g -1 . CR-SIDM interactions, however, limit the possible DM-baryon cross section to (less-or-similar sign)5x10 -3 cm 2 g -1 ; this rules out an energy-independent interaction, but not one which falls with center-of-mass velocity s∝1/v or steeper

  16. A theory overview on the Compressed Baryonic Matter Experiment at FAIR

    International Nuclear Information System (INIS)

    Nahrgang, Marlene

    2014-01-01

    The Compressed Baryonic Matter (CBM) experiment at FAIR offers for the first time in heavy-ion physics the opportunity to investigate extremely baryon-dense strongly interacting matter with large data samples as a basis for high precision measurements. This will allow us to put theories at test, answer questions about the structure of the phase diagram of QCD and the transport properties of the medium. In this overview I will highlight some recent advances on several key questions, which will be addressed by the CBM experiment.

  17. Relative velocity of dark matter and baryonic fluids and the formation of the first structures

    International Nuclear Information System (INIS)

    Tseliakhovich, Dmitriy; Hirata, Christopher

    2010-01-01

    At the time of recombination, baryons and photons decoupled and the sound speed in the baryonic fluid dropped from relativistic, ∼c/√(3), to the thermal velocities of the hydrogen atoms, ∼2x10 -5 c. This is less than the relative velocities of baryons and dark matter computed via linear perturbation theory, so we infer that there are supersonic coherent flows of the baryons relative to the underlying potential wells created by the dark matter. As a result, the advection of small-scale perturbations (near the baryonic Jeans scale) by large-scale velocity flows is important for the formation of the first structures. This effect involves a quadratic term in the cosmological perturbation theory equations and hence has not been included in studies based on linear perturbation theory. We show that the relative motion suppresses the abundance of the first bound objects, even if one only investigates dark matter haloes, and leads to qualitative changes in their spatial distribution, such as introducing scale-dependent bias and stochasticity. We further discuss the possible observable implications of this effect for high-redshift galaxy clustering and reionization.

  18. Constraints on the interaction between dark matter and Baryons from cooling flow clusters.

    Science.gov (United States)

    Qin, B; Wu, X P

    2001-08-06

    Other nongravitational heating processes are needed to resolve the disagreement between the absence of cool gas components in the centers of galaxy clusters revealed recently by Chandra and XMM observations and the expectations of conventional radiative cooling models. We propose that the interaction between dark matter and baryonic matter may act as an alternative for the reheating of intracluster medium (ICM) in the inner regions of clusters, in which kinetic energy of dark matter is transported to ICM to balance radiative cooling. Using the Chandra and XMM data, we set a useful constraint on the dark-matter-baryon cross section: sigma(xp)/m(x) approximately 1x10(-25) cm(2) GeV-1, where m(x) is the mass of dark matter particles.

  19. Lattice QCD for Baryon Rich Matter – Beyond Taylor Expansions

    Energy Technology Data Exchange (ETDEWEB)

    Bornyakov, V. [ITEP, B. Cheremushkinskaya 25, Moscow, 117218 (Russian Federation); School of Biomedicine, Far Eastern Federal University, Sukhanova 8, Vladivostok 690950 (Russian Federation); Boyda, D. [School of Biomedicine, Far Eastern Federal University, Sukhanova 8, Vladivostok 690950 (Russian Federation); Goy, V. [School of Natural Sciences, Far Eastern Federal University, Sukhanova 8, Vladivostok 690950 (Russian Federation); Molochkov, A. [School of Biomedicine, Far Eastern Federal University, Sukhanova 8, Vladivostok 690950 (Russian Federation); Nakamura, A. [School of Biomedicine, Far Eastern Federal University, Sukhanova 8, Vladivostok 690950 (Russian Federation); Research Center for Nuclear Physics (RCNP), Osaka University, Ibaraki, Osaka, 567-0047 (Japan); Theoretical Research Division, Nishina Center, RIKEN, Wako 351-0198 (Japan); Nikolaev, A. [School of Biomedicine, Far Eastern Federal University, Sukhanova 8, Vladivostok 690950 (Russian Federation); Zakharov, V.I. [ITEP, B. Cheremushkinskaya 25, Moscow, 117218 (Russian Federation); School of Biomedicine, Far Eastern Federal University, Sukhanova 8, Vladivostok 690950 (Russian Federation); Moscow Inst Phys & Technol, Dolgoprudny, Moscow Region, 141700 (Russian Federation)

    2016-12-15

    We discuss our study for exploring the QCD phase diagram based on the lattice QCD. To go beyond the Taylor expansion and to reach higher density regions, we employ the canonical approach. In order to produce lattice data which meet experimental situation as much as possible, we propose a canonical approach with the charge and baryon number. We present our lattice QCD GPU code for this project which employs the clover improved Wilson fermions and Iwasaki gauge action to investigate pure imaginary chemical potential.

  20. Lattice QCD for Baryon Rich Matter – Beyond Taylor Expansions

    International Nuclear Information System (INIS)

    Bornyakov, V.; Boyda, D.; Goy, V.; Molochkov, A.; Nakamura, A.; Nikolaev, A.; Zakharov, V.I.

    2016-01-01

    We discuss our study for exploring the QCD phase diagram based on the lattice QCD. To go beyond the Taylor expansion and to reach higher density regions, we employ the canonical approach. In order to produce lattice data which meet experimental situation as much as possible, we propose a canonical approach with the charge and baryon number. We present our lattice QCD GPU code for this project which employs the clover improved Wilson fermions and Iwasaki gauge action to investigate pure imaginary chemical potential.

  1. Probing sub-GeV dark matter-baryon scattering with cosmological observables

    Science.gov (United States)

    Xu, Weishuang Linda; Dvorkin, Cora; Chael, Andrew

    2018-05-01

    We derive new limits on the elastic scattering cross section between baryons and dark matter using cosmic microwave background data from the Planck satellite and measurements of the Lyman-alpha forest flux power spectrum from the Sloan Digital Sky Survey. Our analysis addresses generic cross sections of the form σ ∝vn , where v is the dark matter-baryon relative velocity, allowing for constraints on the cross section independent of specific particle physics models. We include high-ℓ polarization data from Planck in our analysis, improving over previous constraints. We apply a more careful treatment of dark matter thermal evolution than previously done, allowing us to extend our constraints down to dark matter masses of ˜MeV . We show in this work that cosmological probes are complementary to current direct detection and astrophysical searches.

  2. Is there a dichotomy in the Dark Matter as well as in the Baryonic Matter properties of ellipticals?

    NARCIS (Netherlands)

    Napolitano, NR; Capaccioli, M; Arnaboldi, M; Merrifield, MR; Douglas, NG; Kuijken, K; Romanowsky, AJ; Freeman, KC; Ryder, SD; Pisano, DJ; Walker, MA; Freeman, KC

    2004-01-01

    We have found a correlation between the M/L global gradients and the structural parameters of the luminous components of a sample of 19 early-type galaxies. Such a correlation supports the hypothesis that there is a connection between the dark matter content and the evolution of the baryonic

  3. The impact of baryons on the direct detection of dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Kelso, Chris [Department of Physics, University of North Florida, Jacksonville, FL 32224 (United States); Savage, Christopher; Freese, Katherine [Nordita, KTH Royal Institute of Technology and Stockholm University, SE-106 91 Stockholm (Sweden); Valluri, Monica [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States); Stinson, Gregory S. [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117, Heidelberg (Germany); Bailin, Jeremy, E-mail: ckelso@unf.edu, E-mail: chris@savage.name, E-mail: mvalluri@umich.edu, E-mail: ktfreese@umich.edu, E-mail: stinson@mpia.de, E-mail: jbailin@ua.edu [Department of Physics and Astronomy, University of Alabama, Tuscaloosa, AL 35487 (United States)

    2016-08-01

    The spatial and velocity distributions of dark matter particles in the Milky Way Halo affect the signals expected to be observed in searches for dark matter. Results from direct detection experiments are often analyzed assuming a simple isothermal distribution of dark matter, the Standard Halo Model (SHM). Yet there has been skepticism regarding the validity of this simple model due to the complicated gravitational collapse and merger history of actual galaxies. In this paper we compare the SHM to the results of cosmological hydrodynamical simulations of galaxy formation to investigate whether or not the SHM is a good representation of the true WIMP distribution in the analysis of direct detection data. We examine two Milky Way-like galaxies from the MaGICC cosmological simulations (a) with dark matter only and (b) with baryonic physics included. The inclusion of baryons drives the shape of the DM halo to become more spherical and makes the velocity distribution of dark matter particles less anisotropic especially at large heliocentric velocities, thereby making the SHM a better fit. We also note that we do not find a significant disk-like rotating dark matter component in either of the two galaxy halos with baryons that we examine, suggesting that dark disks are not a generic prediction of cosmological hydrodynamical simulations. We conclude that in the Solar neighborhood, the SHM is in fact a good approximation to the true dark matter distribution in these cosmological simulations (with baryons) which are reasonable representations of the Milky Way, and hence can also be used for the purpose of dark matter direct detection calculations.

  4. White noise from dark matter: 21 cm observations of early baryon collapse

    International Nuclear Information System (INIS)

    Zurek, Kathryn M.; Hogan, Craig J.

    2007-01-01

    In concordance cosmology, dark matter density perturbations generated by inflation lead to nonlinear, virialized minihalos, into which baryons collapse at redshift z∼20. We survey here novel baryon evolution produced by a modification of the power spectrum from white noise density perturbations at scales below k∼10h Mpc -1 (the smallest scales currently measured with the Lyman-α forest). Exotic dark matter dynamics, such as would arise from scalar dark matter with a late phase transition (similar to an axion, but with lower mass), or primordial black hole dark matter, create such an amplification of small scale power. The dark matter produced in such a phase transition collapses into minihalos, with a size given by the dark matter mass within the horizon at the phase transition. If the mass of the initial minihalos is larger than ∼10 -3 M · , the modified power spectrum is found to cause widespread baryon collapse earlier than standard ΛCDM, leading to earlier gas heating. It also results in higher spin temperature of the baryons in the 21 cm line relative to ΛCDM at redshifts z>20 if the mass of the minihalo is larger than 1M · . It is estimated that experiments probing 21 cm radiation at high redshift will contribute a significant constraint on dark matter models of this type for initial minihalos larger than ∼10M · . These experiments may also detect (or rule out) primordial black holes as the dark matter in the window 30M · H 3 M · still left open by strong microlensing experiments and other astrophysical constraints. Early experiments reaching to z≅15 will constrain minihalos down to ∼10 3 M ·

  5. Emergence of the mass discrepancy-acceleration relation from dark matter-baryon interactions

    Science.gov (United States)

    Famaey, Benoit; Khoury, Justin; Penco, Riccardo

    2018-03-01

    The observed tightness of the mass discrepancy-acceleration relation (MDAR) poses a fine-tuning challenge to current models of galaxy formation. We propose that this relation could arise from collisional interactions between baryons and dark matter (DM) particles, without the need for modification of gravity or ad hoc feedback processes. We assume that these interactions satisfy the following three conditions: (i) the relaxation time of DM particles is comparable to the dynamical time in disk galaxies; (ii) DM exchanges energy with baryons due to elastic collisions; (iii) the product between the baryon-DM cross section and the typical energy exchanged in a collision is inversely proportional to the DM number density. As a proof of principle, we present an example of a particle physics model that gives a DM-baryon cross section with the desired density and velocity dependence. For consistency with direct detection constraints, our DM particles must be either very light (m ll mb) or very heavy (mgg mb), corresponding respectively to heating and cooling of DM by baryons. In both cases, our mechanism applies and an equilibrium configuration can in principle be reached. In this exploratory paper, we focus on the heavy DM/cooling case because it is technically simpler, since the average energy exchanged turns out to be approximately constant throughout galaxies. Under these assumptions, we find that rotationally-supported disk galaxies could naturally settle to equilibrium configurations satisfying a MDAR at all radii without invoking finely tuned feedback processes. We also discuss issues related to the small scale clumpiness of baryons, as well as predictions for pressure-supported systems. We argue in particular that galaxy clusters do not follow the MDAR despite being DM-dominated because they have not reached their equilibrium configuration. Finally, we revisit existing phenomenological, astrophysical and cosmological constraints on baryon-DM interactions in light

  6. Revisiting the gravitino dark matter and baryon asymmetry from Q-ball decay in gauge mediation

    Energy Technology Data Exchange (ETDEWEB)

    Kasuya, Shinta, E-mail: kasuya@kanagawa-u.ac.jp [Department of Mathematics and Physics, Kanagawa University, Kanagawa 259-1293 (Japan); Max-Planck-Institut für Kernphysik, PO Box 103980, 69029 Heidelberg (Germany); Kawasaki, Masahiro [Institute for Cosmic Ray Research, the University of Tokyo, Chiba 277-8582 (Japan); Kavli Institute for the Physics and Mathematics of the Universe (WPI), Todai Institutes for Advanced Study, the University of Tokyo, Chiba 277-8582 (Japan); Yamada, Masaki [Institute for Cosmic Ray Research, the University of Tokyo, Chiba 277-8582 (Japan)

    2013-10-07

    We reconsider the Q-ball decay and reinvestigate the scenario that the amount of the baryons and the gravitino dark matter is naturally explained by the decay of the Q balls in the gauge-mediated SUSY breaking. We refine the decay rates into baryons, NLSPs, and gravitinos, and estimate their branching ratios based on the consideration of Pauli blocking. We obtain a smaller branching into gravitinos than the previous estimate, and the NLSPs are more produced by the Q-ball decay. However, the efficient annihilations of NLSPs occur afterward so that their abundance does not spoil the successful BBN and they only produce negligible amount of the gravitinos to the dark matter density by their decay. In this way, we find that the scenario with the direct production of the gravitino dark matter from the Q-ball decay works naturally.

  7. Evolution of Mass and Velocity Field in the Cosmic Web: Comparison between Baryonic and Dark Matter

    Science.gov (United States)

    Zhu, Weishan; Feng, Long-Long

    2017-03-01

    We investigate the evolution of the cosmic web since z = 5 in grid-based cosmological hydrodynamical simulations, focusing on the mass and velocity fields of both baryonic and cold dark matter. The tidal tensor of density is used as the main method for web identification, with λ th = 0.2-1.2. The evolution trends in baryonic and dark matter are similar, although moderate differences are observed. Sheets appear early, and their large-scale pattern may have been set up by z = 3. In terms of mass, filaments supersede sheets as the primary collapsing structures from z ˜ 2-3. Tenuous filaments assembled with each other to form prominent ones at z dark matter field, and is even moderately stronger between {\\boldsymbol{ω }} and {{\\boldsymbol{e}}}1, and ω and {{\\boldsymbol{e}}}3. Compared with dark matter, there is slightly less baryonic matter found residing in filaments and clusters, and its vorticity developed more significantly below 2-3 Mpc. These differences may be underestimated because of the limited resolution and lack of star formation in our simulation. The impact of the change of dominant structures in overdense regions at z ˜ 2-3 on galaxy formation and evolution is shortly discussed.

  8. The dark-baryonic matter mass relation for observational verification in Verlinde's emergent gravity

    Science.gov (United States)

    Shen, Jian Qi

    2018-06-01

    Recently, a new interesting idea of origin of gravity has been developed by Verlinde. In this scheme of emergent gravity, where horizon entropy, microscopic de Sitter states and relevant contribution to gravity are involved, an entropy displacement resulting from matter behaves as a memory effect and can be exhibited at sub-Hubble scales, namely, the entropy displacement and its "elastic" response would lead to emergent gravity, which gives rise to an extra gravitational force. Then galactic dark matter effects may origin from such extra emergent gravity. We discuss some concepts in Verlinde's theory of emergent gravity and point out some possible problems or issues, e.g., the gravitational potential caused by Verlinde's emergent apparent dark matter may no longer be continuous in spatial distribution at ordinary matter boundary (such as a massive sphere surface). In order to avoid the unnatural discontinuity of the extra emergent gravity of Verlinde's apparent dark matter, we suggest a modified dark-baryonic mass relation (a formula relating Verlinde's apparent dark matter mass to ordinary baryonic matter mass) within this framework of emergent gravity. The modified mass relation is consistent with Verlinde's result at relatively small scales (e.g., R3h_{70}^{-1} Mpc), the modified dark-baryonic mass relation presented here might be in better agreement with the experimental curves of weak lensing analysis in the recent work of Brouwer et al. Galactic rotation curves are compared between Verlinde's emergent gravity and McGaugh's recent model of MOND (Modified Newtonian Dynamics established based on recent galaxy observations). It can be found that Verlinde rotational curves deviate far from those of McGaugh MOND model when the MOND effect (or emergent dark matter) dominates. Some applications of the modified dark-baryonic mass relation inspired by Verlinde's emergent gravity will be addressed for galactic and solar scales. Potential possibilities to test this dark-baryonic

  9. Neutrino physics with dark matter experiments and the signature of new baryonic neutral currents

    International Nuclear Information System (INIS)

    Pospelov, Maxim

    2011-01-01

    New neutrino states ν b , sterile under the standard model interactions, can be coupled to baryons via the isoscalar vector currents that are much stronger than the standard model weak interactions. If some fraction of solar neutrinos oscillate into ν b on their way to Earth, the coherently enhanced elastic ν b -nucleus scattering can generate a strong signal in the dark matter detectors. For the interaction strength a few hundred times stronger than the weak force, the elastic ν b -nucleus scattering via new baryonic currents may account for the existing anomalies in the direct detection dark matter experiments at low recoil. We point out that for solar-neutrino energies, the baryon-current-induced inelastic scattering is suppressed, so that the possible enhancement of a new force is not in conflict with signals at dedicated neutrino detectors. We check this explicitly by calculating the ν b -induced deuteron breakup, and the excitation of a 4.4 MeV γ line in 12 C. A stronger-than-weak force coupled to the baryonic current implies the existence of a new Abelian gauge group U(1) B with a relatively light gauge boson.

  10. Relating the baryon asymmetry to the thermal relic dark matter density

    International Nuclear Information System (INIS)

    McDonald, John

    2011-01-01

    We present a generic framework, baryomorphosis, which modifies the baryon asymmetry to be naturally of the order of a typical thermal relic weakly interacting massive particle (WIMP) density. We consider a simple scalar-based model to show how this is possible. This model introduces a sector in which a large initial baryon asymmetry is injected into particles ('annihilons'), φ B , φ-circumflex B , of mass ∼100 GeV-1 TeV. φ B φ-circumflex B annihilations convert the initial φ B , φ-circumflex B asymmetry to a final asymmetry with a thermal relic WIMP-like density. This subsequently decays to a conventional baryon asymmetry whose magnitude is naturally related to the density of thermal relic WIMP dark matter. In this way the two coincidences of baryons and dark matter, i.e. why their densities are similar to each other and why they are both similar to a WIMP thermal relic density (the 'WIMP miracle'), may be understood. The model may be tested by the production of annihilons at colliders.

  11. Interplay of mesonic and baryonic degrees of freedom in quark matter

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Naseemuddin

    2015-11-03

    In this work we study the influence of mesonic and baryonic fluctuations on the phase diagram of quark matter with two flavors. By examining the hadronization process and related techniques, we derive effective low-energy models, where the gluons are integrated out. To be able to compare our model calculations with lattice results at finite chemical potential, we investigate a QCD-like theory with two colors, where the sign-problem is absent. To this end we introduce a quark-meson-diquark model, where the bosonic diquarks play the role of colorless, baryonic degrees of freedom competing with the mesons. To access the phase diagram and determine the phases of chiral and diquark condensation, we employ a functional renormalization group approach allowing for a systematic non-perturbative truncation scheme. Interesting phenomena arise that are known from condensed matter physics, as the BEC-BSC crossover and a phase of condensation within domains. We explore the impact of running wave function renormalizations and Yukawa couplings for the quarks and the boson fields on top of the scale dependence of the effective potential. In the course of this we discuss the Silver Blaze property and its realization within a functional approach. In parallel, we formulate a quark-meson-diquark-baryon model for physical QCD as a low-energy effective theory for baryonic matter at high density, and discuss the relevance of the diquark and baryon degrees of freedom. In this sense, we compute a phase diagram for QCD from functional methods, including a color superconducting phase.

  12. Heavy baryon clusters and search for signals of quark matter formation

    International Nuclear Information System (INIS)

    Gagarin, Yu.F.; Kalinkin, B.N.

    2000-01-01

    New experimental data are discussed on the distribution of protons over transverse momentum of p perpendicular to in the Fe+Em process at energies 2-200 GeV/n and of α-particles in the Au + Em process at incident energy 10.7 GeV/n. A possible interpretation of the experiment within the framework of the gluon dominance and the thermodynamic approximation can be achieved with a minor additional assumption only. This assumption is that at an early stage of evolution of the heavy baryon cluster matter the quark matter transforms into baryons at a temperature T ∼ 0.22 GeV and its global decay into nucleons is completed at T ∼ 0.14 GeV. The results are also of interest in connection with the problem of abundance of helium and hydrogen in the universe which has been considered in cosmology and astrophysics for a long time. (orig.)

  13. Relativistic shocks in the systems containing domains with anomalous equation of state and quark baryonic matter hadronization

    International Nuclear Information System (INIS)

    Bugaev, K.A.; Gorenshtejn, M.I.; Zhdanov, V.I.

    1987-01-01

    Theoretical basis for general stability criterion of relativistic shocks in baryonic matter is proposed. Different formulations of shock mechanical stability are considered and applied to the analysis of rarefaction shock hadronization transition. 13 refs.; 2 figs

  14. Primordial nucleosynthesis in inhomogeneous cosmologies: Ω = 1 with baryonic dark matter

    International Nuclear Information System (INIS)

    Mathews, G.J.; Sale, K.E.

    1986-09-01

    We consider the constraints on Ω from primordial nucleosynthesis in inhomogeneous cosmologies. We find that allowance for isothermal fluctuations significantly weakens the upper bound on the average value of Ω derived from the standard big bang. Under the plausible additional assumption that regions of high baryon density are preferentially absorbed into cold dark matter, the constraints from primordial nucleosynthesis can be satisfied for large values of Ω, including Ω = 1. 22 refs., 2 figs

  15. The fixed target experiment for studies of baryonic matter at the Nuclotron (BM rate at N)

    Energy Technology Data Exchange (ETDEWEB)

    Kapishin, Mikhail [Joint Institute for Nuclear Research, Dubna, Moscow region (Russian Federation)

    2016-08-15

    BM rate at N (Baryonic Matter at Nuclotron) is the first experiment to be realized at the accelerator complex of NICA-Nuclotron. The aim of the BM rate at N experiment is to study interactions of relativistic heavy-ion beams with fixed targets. The BM rate at N setup, results of Monte Carlo simulations and the BM rate at N experimental program are presented. (orig.)

  16. Probing the nuclear matter at high baryon and isospin density with heavy ion collisions

    International Nuclear Information System (INIS)

    Di Toro, M.; Colonna, M.; Ferini, G.

    2010-01-01

    Heavy Ion Collisions (HIC) represent a unique tool to probe the in-medium nuclear interaction in regions away from saturation. High Energy Collisions are studied in order to access nuclear matter properties at high density. Particular attention is devoted to the selection of observables sensitive to the poorly known symmetry energy at high baryon density, of large fundamental interest, even for the astrophysics implications. Using fully consistent covariant transport simulations built on effective field theories we are testing isospin observables ranging from nucleon/cluster emissions, collective flows (in particular the elliptic, squeeze out, part) and meson production. The possibility to shed light on the controversial neutron/proton effective mass splitting in asymmetric matter is also stressed. The "symmetry" repulsion at high baryon density will also lead to an "earlier" hadron-deconfinement transition in n-rich matter. The phase transition of hadronic to quark matter at high baryon and isospin density is analyzed. Nonlinear relativistic mean field models are used to describe hadronic matter, and the MIT bag model is adopted for quark matter. The boundaries of the mixed phase and the related critical points for symmetric and asymmetric matter are obtained. Isospin effects appear to be rather significant. The binodal transition line of the (T,ρ B ) diagram is lowered in a region accessible to heavy ion collisions in the energy range of the new planned FAIR/NICA facilities. Some observable effects of the mixed phase are suggested, in particular a neutron distillation mechanism. Theoretically a very important problem appears to be the suitable treatment of the isovector part of the interaction in effective QCD lagrangian approaches. (author)

  17. Scale-chiral symmetry, ω meson, and dense baryonic matter

    Science.gov (United States)

    Ma, Yong-Liang; Rho, Mannque

    2018-05-01

    It is shown that explicitly broken scale symmetry is essential for dense skyrmion matter in hidden local symmetry theory. Consistency with the vector manifestation fixed point for the hidden local symmetry of the lowest-lying vector mesons and the dilaton limit fixed point for scale symmetry in dense matter is found to require that the anomalous dimension (|γG2| ) of the gluon field strength tensor squared (G2 ) that represents the quantum trace anomaly should be 1.0 ≲|γG2|≲3.5 . The magnitude of |γG2| estimated here will be useful for studying hadron and nuclear physics based on the scale-chiral effective theory. More significantly, that the dilaton limit fixed point can be arrived at with γG2≠0 at some high density signals that scale symmetry can arise in dense medium as an "emergent" symmetry.

  18. Does dark matter consist of baryons of new stable family quarks?

    International Nuclear Information System (INIS)

    Bregar, G.; Mankoc Borstnik, N. S.

    2009-01-01

    We investigate the possibility that the dark matter consists of clusters of the heavy family quarks and leptons with zero Yukawa couplings to the lower families. Such a family is predicted by the approach unifying spin and charges as the fifth family. We make a rough estimation of properties of baryons of these new family members, of their behavior during the evolution of the Universe and when scattering on the ordinary matter, and study possible limitations on the family properties due to the cosmological and direct experimental evidences.

  19. A small amount of mini-charged dark matter could cool the baryons in the early Universe.

    Science.gov (United States)

    Muñoz, Julian B; Loeb, Abraham

    2018-05-01

    The dynamics of our Universe is strongly influenced by pervasive-albeit elusive-dark matter, with a total mass about five times the mass of all the baryons 1,2 . Despite this, its origin and composition remain a mystery. All evidence for dark matter relies on its gravitational pull on baryons, and thus such evidence does not require any non-gravitational coupling between baryons and dark matter. Nonetheless, some small coupling would explain the comparable cosmic abundances of dark matter and baryons 3 , as well as solving structure-formation puzzles in the pure cold-dark-matter models 4 . A vast array of observations has been unable to find conclusive evidence for any non-gravitational interactions of baryons with dark matter 5-9 . Recent observations by the EDGES collaboration, however, suggest that during the cosmic dawn, roughly 200 million years after the Big Bang, the baryonic temperature was half of its expected value 10 . This observation is difficult to reconcile with the standard cosmological model but could be explained if baryons are cooled down by interactions with dark matter, as expected if their interaction rate grows steeply at low velocities 11 . Here we report that if a small fraction-less than one per cent-of the dark matter has a mini-charge, a million times smaller than the charge on the electron, and a mass in the range of 1-100 times the electron mass, then the data 10 from the EDGES experiment can be explained while remaining consistent with all other observations. We also show that the entirety of the dark matter cannot have a mini-charge.

  20. Structure formation by the fifth force: Segregation of baryons and dark matter

    International Nuclear Information System (INIS)

    Li Baojiu; Zhao Hongsheng

    2010-01-01

    In this paper we present the results of N-body simulations with a scalar field coupled differently to cold dark matter (CDM) and baryons. The scalar field potential and coupling function are chosen such that the scalar field acquires a heavy mass in regions with high CDM density and thus behaves like a chameleon. We focus on how the existence of the scalar field affects the formation of nonlinear large-scale structures, and how the different couplings of the scalar field to baryons and CDM particles lead to different distributions and evolutions for these two matter species, both on large scales and inside virialized halos. As expected, the baryon-CDM segregation increases in regions where the fifth force is strong, and little segregation in dense regions. We also introduce an approximation method to identify the virialized halos in coupled scalar field models which takes into account the scalar field coupling and which is easy to implement numerically. It is found that the chameleon nature of the scalar field makes the internal density profiles of halos dependent on the environment in a very nontrivial way.

  1. Neutron star properties and the relativistic nuclear equation of state of many-baryon matter

    International Nuclear Information System (INIS)

    Weber, F.; Weigel, M.K.

    1989-01-01

    A relativistic model of baryons interacting via the exchange of σ-, ω-, π- and ρ-mesons (scalar-vector-isovector (SVI) theory) is used to describe the properties of both dense and superdense matter. For the theoretical frame, we used the temperature-dependent Green's function formalism. The equation of state (EOS) is calculated for nuclear as well as neutron matter in the Hartree (H) and Hartree-Fock (HF) approximation. The existence of phase transitions has been investigated. The isotherms of pressure as a function of density show for nuclear matter a critical temperature of about T c HF =16.6 MeV. (As in the usual scalar-vector (SV) theory, the phase transition is absent for neutron matter. A phase transition of both many-baryon systems in the high-pressure and high-density region, which has been found within the SV many-baryon theory, appears in the SVI theory too. The calculated maximum stable masses of neutron stars depend on 1. the underlying parameter set and/or 2. on the chosen approximation (i.e., H, HF; SV-, SVI theory, respectively). Hartree calculations lead to a mass stability limit of M max H ≤2.87 M sun (M max H ≤2.44 M sun when hyperons are taken into account). For the HF calculations we obtained M max HF ≤3.00 M sun (M max HF ≤2.85 M sun ). The corresponding maximum radii are (same notation as above) R H ≤13.2 km (R H ≤11.8 km), R HF ≤14.0 km (R HF ≤13.94 km).) The influence of the approximations, parameter sets and hyperons on the neutron star's moment of inertia is exhibited. (orig.)

  2. A simple testable model of baryon number violation: Baryogenesis, dark matter, neutron-antineutron oscillation and collider signals

    Science.gov (United States)

    Allahverdi, Rouzbeh; Dev, P. S. Bhupal; Dutta, Bhaskar

    2018-04-01

    We study a simple TeV-scale model of baryon number violation which explains the observed proximity of the dark matter and baryon abundances. The model has constraints arising from both low and high-energy processes, and in particular, predicts a sizable rate for the neutron-antineutron (n - n bar) oscillation at low energy and the monojet signal at the LHC. We find an interesting complementarity among the constraints arising from the observed baryon asymmetry, ratio of dark matter and baryon abundances, n - n bar oscillation lifetime and the LHC monojet signal. There are regions in the parameter space where the n - n bar oscillation lifetime is found to be more constraining than the LHC constraints, which illustrates the importance of the next-generation n - n bar oscillation experiments.

  3. arXiv Measurement of matter-antimatter differences in beauty baryon decays

    CERN Document Server

    Aaij, Roel; Adinolfi, Marco; Ajaltouni, Ziad; Akar, Simon; Albrecht, Johannes; Alessio, Federico; Alexander, Michael; Ali, Suvayu; Alkhazov, Georgy; Alvarez Cartelle, Paula; Alves Jr, Antonio Augusto; Amato, Sandra; Amerio, Silvia; Amhis, Yasmine; An, Liupan; Anderlini, Lucio; Andreassi, Guido; Andreotti, Mirco; Andrews, Jason; Appleby, Robert; Archilli, Flavio; d'Argent, Philippe; Arnau Romeu, Joan; Artamonov, Alexander; Artuso, Marina; Aslanides, Elie; Auriemma, Giulio; Baalouch, Marouen; Babuschkin, Igor; Bachmann, Sebastian; Back, John; Badalov, Alexey; Baesso, Clarissa; Baker, Sophie; Baldini, Wander; Barlow, Roger; Barschel, Colin; Barsuk, Sergey; Barter, William; Baszczyk, Mateusz; Batozskaya, Varvara; Batsukh, Baasansuren; Battista, Vincenzo; Bay, Aurelio; Beaucourt, Leo; Beddow, John; Bedeschi, Franco; Bediaga, Ignacio; Bel, Lennaert; Bellee, Violaine; Belloli, Nicoletta; Belous, Konstantin; Belyaev, Ivan; Ben-Haim, Eli; Bencivenni, Giovanni; Benson, Sean; Benton, Jack; Berezhnoy, Alexander; Bernet, Roland; Bertolin, Alessandro; Betti, Federico; Bettler, Marc-Olivier; van Beuzekom, Martinus; Bezshyiko, Iaroslava; Bifani, Simone; Billoir, Pierre; Bird, Thomas; Birnkraut, Alex; Bitadze, Alexander; Bizzeti, Andrea; Blake, Thomas; Blanc, Frederic; Blouw, Johan; Blusk, Steven; Bocci, Valerio; Boettcher, Thomas; Bondar, Alexander; Bondar, Nikolay; Bonivento, Walter; Borgheresi, Alessio; Borghi, Silvia; Borisyak, Maxim; Borsato, Martino; Bossu, Francesco; Boubdir, Meriem; Bowcock, Themistocles; Bowen, Espen Eie; Bozzi, Concezio; Braun, Svende; Britsch, Markward; Britton, Thomas; Brodzicka, Jolanta; Buchanan, Emma; Burr, Christopher; Bursche, Albert; Buytaert, Jan; Cadeddu, Sandro; Calabrese, Roberto; Calvi, Marta; Calvo Gomez, Miriam; Camboni, Alessandro; Campana, Pierluigi; Campora Perez, Daniel; Campora Perez, Daniel Hugo; Capriotti, Lorenzo; Carbone, Angelo; Carboni, Giovanni; Cardinale, Roberta; Cardini, Alessandro; Carniti, Paolo; Carson, Laurence; Carvalho Akiba, Kazuyoshi; Casse, Gianluigi; Cassina, Lorenzo; Castillo Garcia, Lucia; Cattaneo, Marco; Cauet, Christophe; Cavallero, Giovanni; Cenci, Riccardo; Charles, Matthew; Charpentier, Philippe; Chatzikonstantinidis, Georgios; Chefdeville, Maximilien; Chen, Shanzhen; Cheung, Shu-Faye; Chobanova, Veronika; Chrzaszcz, Marcin; Cid Vidal, Xabier; Ciezarek, Gregory; Clarke, Peter; Clemencic, Marco; Cliff, Harry; Closier, Joel; Coco, Victor; Cogan, Julien; Cogneras, Eric; Cogoni, Violetta; Cojocariu, Lucian; Collazuol, Gianmaria; Collins, Paula; Comerma-Montells, Albert; Contu, Andrea; Cook, Andrew; Coquereau, Samuel; Corti, Gloria; Corvo, Marco; Costa Sobral, Cayo Mar; Couturier, Benjamin; Cowan, Greig; Craik, Daniel Charles; Crocombe, Andrew; Cruz Torres, Melissa Maria; Cunliffe, Samuel; Currie, Robert; D'Ambrosio, Carmelo; Da Cunha Marinho, Franciole; Dall'Occo, Elena; Dalseno, Jeremy; David, Pieter; Davis, Adam; De Aguiar Francisco, Oscar; De Bruyn, Kristof; De Capua, Stefano; De Cian, Michel; De Miranda, Jussara; De Paula, Leandro; De Serio, Marilisa; De Simone, Patrizia; Dean, Cameron Thomas; Decamp, Daniel; Deckenhoff, Mirko; Del Buono, Luigi; Demmer, Moritz; Derkach, Denis; Deschamps, Olivier; Dettori, Francesco; Dey, Biplab; Di Canto, Angelo; Dijkstra, Hans; Dordei, Francesca; Dorigo, Mirco; Dosil Suárez, Alvaro; Dovbnya, Anatoliy; Dreimanis, Karlis; Dufour, Laurent; Dujany, Giulio; Dungs, Kevin; Durante, Paolo; Dzhelyadin, Rustem; Dziurda, Agnieszka; Dzyuba, Alexey; Déléage, Nicolas; Easo, Sajan; Ebert, Marcus; Egede, Ulrik; Egorychev, Victor; Eidelman, Semen; Eisenhardt, Stephan; Eitschberger, Ulrich; Ekelhof, Robert; Eklund, Lars; Elsasser, Christian; Ely, Scott; Esen, Sevda; Evans, Hannah Mary; Evans, Timothy; Falabella, Antonio; Farley, Nathanael; Farry, Stephen; Fay, Robert; Fazzini, Davide; Ferguson, Dianne; Fernandez Albor, Victor; Fernandez Prieto, Antonio; Ferrari, Fabio; Ferreira Rodrigues, Fernando; Ferro-Luzzi, Massimiliano; Filippov, Sergey; Fini, Rosa Anna; Fiore, Marco; Fiorini, Massimiliano; Firlej, Miroslaw; Fitzpatrick, Conor; Fiutowski, Tomasz; Fleuret, Frederic; Fohl, Klaus; Fontana, Marianna; Fontanelli, Flavio; Forshaw, Dean Charles; Forty, Roger; Franco Lima, Vinicius; Frank, Markus; Frei, Christoph; Fu, Jinlin; Furfaro, Emiliano; Färber, Christian; Gallas Torreira, Abraham; Galli, Domenico; Gallorini, Stefano; Gambetta, Silvia; Gandelman, Miriam; Gandini, Paolo; Gao, Yuanning; Garcia Martin, Luis Miguel; García Pardiñas, Julián; Garra Tico, Jordi; Garrido, Lluis; Garsed, Philip John; Gascon, David; Gaspar, Clara; Gavardi, Laura; Gazzoni, Giulio; Gerick, David; Gersabeck, Evelina; Gersabeck, Marco; Gershon, Timothy; Ghez, Philippe; Gianì, Sebastiana; Gibson, Valerie; Girard, Olivier Göran; Giubega, Lavinia-Helena; Gizdov, Konstantin; Gligorov, V.V.; Golubkov, Dmitry; Golutvin, Andrey; Gomes, Alvaro; Gorelov, Igor Vladimirovich; Gotti, Claudio; Grabalosa Gándara, Marc; Graciani Diaz, Ricardo; Granado Cardoso, Luis Alberto; Graugés, Eugeni; Graverini, Elena; Graziani, Giacomo; Grecu, Alexandru; Griffith, Peter; Grillo, Lucia; Gruberg Cazon, Barak Raimond; Grünberg, Oliver; Gushchin, Evgeny; Guz, Yury; Gys, Thierry; Göbel, Carla; Hadavizadeh, Thomas; Hadjivasiliou, Christos; Haefeli, Guido; Haen, Christophe; Haines, Susan; Hall, Samuel; Hamilton, Brian; Han, Xiaoxue; Hansmann-Menzemer, Stephanie; Harnew, Neville; Harnew, Samuel; Harrison, Jonathan; Hatch, Mark; He, Jibo; Head, Timothy; Heister, Arno; Hennessy, Karol; Henrard, Pierre; Henry, Louis; Hernando Morata, Jose Angel; van Herwijnen, Eric; Heß, Miriam; Hicheur, Adlène; Hill, Donal; Hombach, Christoph; Hopchev, P H; Hulsbergen, Wouter; Humair, Thibaud; Hushchyn, Mikhail; Hussain, Nazim; Hutchcroft, David; Idzik, Marek; Ilten, Philip; Jacobsson, Richard; Jaeger, Andreas; Jalocha, Pawel; Jans, Eddy; Jawahery, Abolhassan; Jiang, Feng; John, Malcolm; Johnson, Daniel; Jones, Christopher; Joram, Christian; Jost, Beat; Jurik, Nathan; Kandybei, Sergii; Kanso, Walaa; Karacson, Matthias; Kariuki, James Mwangi; Karodia, Sarah; Kecke, Matthieu; Kelsey, Matthew; Kenyon, Ian; Kenzie, Matthew; Ketel, Tjeerd; Khairullin, Egor; Khanji, Basem; Khurewathanakul, Chitsanu; Kirn, Thomas; Klaver, Suzanne; Klimaszewski, Konrad; Koliiev, Serhii; Kolpin, Michael; Komarov, Ilya; Koopman, Rose; Koppenburg, Patrick; Kozachuk, Anastasiia; Kozeiha, Mohamad; Kravchuk, Leonid; Kreplin, Katharina; Kreps, Michal; Krokovny, Pavel; Kruse, Florian; Krzemien, Wojciech; Kucewicz, Wojciech; Kucharczyk, Marcin; Kudryavtsev, Vasily; Kuonen, Axel Kevin; Kurek, Krzysztof; Kvaratskheliya, Tengiz; Lacarrere, Daniel; Lafferty, George; Lai, Adriano; Lambert, Dean; Lanfranchi, Gaia; Langenbruch, Christoph; Latham, Thomas; Lazzeroni, Cristina; Le Gac, Renaud; van Leerdam, Jeroen; Lees, Jean-Pierre; Leflat, Alexander; Lefrançois, Jacques; Lefèvre, Regis; Lemaitre, Florian; Lemos Cid, Edgar; Leroy, Olivier; Lesiak, Tadeusz; Leverington, Blake; Li, Yiming; Likhomanenko, Tatiana; Lindner, Rolf; Linn, Christian; Lionetto, Federica; Liu, Bo; Liu, Xuesong; Loh, David; Longstaff, Iain; Lopes, Jose; Lucchesi, Donatella; Lucio Martinez, Miriam; Luo, Haofei; Lupato, Anna; Luppi, Eleonora; Lupton, Oliver; Lusiani, Alberto; Lyu, Xiao-Rui; Machefert, Frederic; Maciuc, Florin; Maev, Oleg; Maguire, Kevin; Malde, Sneha; Malinin, Alexander; Maltsev, Timofei; Manca, Giulia; Mancinelli, Giampiero; Manning, Peter Michael; Maratas, Jan; Marchand, Jean François; Marconi, Umberto; Marin Benito, Carla; Marino, Pietro; Marks, Jörg; Martellotti, Giuseppe; Martin, Morgan; Martinelli, Maurizio; Martinez Santos, Diego; Martinez Vidal, Fernando; Martins Tostes, Danielle; Massacrier, Laure Marie; Massafferri, André; Matev, Rosen; Mathad, Abhijit; Mathe, Zoltan; Matteuzzi, Clara; Mauri, Andrea; Maurin, Brice; Mazurov, Alexander; McCann, Michael; McCarthy, James; McNab, Andrew; McNulty, Ronan; Meadows, Brian; Meier, Frank; Meissner, Marco; Melnychuk, Dmytro; Merk, Marcel; Merli, Andrea; Michielin, Emanuele; Milanes, Diego Alejandro; Minard, Marie-Noelle; Mitzel, Dominik Stefan; Mogini, Andrea; Molina Rodriguez, Josue; Monroy, Ignacio Alberto; Monteil, Stephane; Morandin, Mauro; Morawski, Piotr; Mordà, Alessandro; Morello, Michael Joseph; Moron, Jakub; Morris, Adam Benjamin; Mountain, Raymond; Muheim, Franz; Mulder, Mick; Mussini, Manuel; Müller, Dominik; Müller, Janine; Müller, Katharina; Müller, Vanessa; Naik, Paras; Nakada, Tatsuya; Nandakumar, Raja; Nandi, Anita; Nasteva, Irina; Needham, Matthew; Neri, Nicola; Neubert, Sebastian; Neufeld, Niko; Neuner, Max; Nguyen, Anh Duc; Nguyen-Mau, Chung; Nieswand, Simon; Niet, Ramon; Nikitin, Nikolay; Nikodem, Thomas; Novoselov, Alexey; O'Hanlon, Daniel Patrick; Oblakowska-Mucha, Agnieszka; Obraztsov, Vladimir; Ogilvy, Stephen; Oldeman, Rudolf; Onderwater, Gerco; Otalora Goicochea, Juan Martin; Otto, Adam; Owen, Patrick; Oyanguren, Maria Aranzazu; Pais, Preema Rennee; Palano, Antimo; Palombo, Fernando; Palutan, Matteo; Panman, Jacob; Papanestis, Antonios; Pappagallo, Marco; Pappalardo, Luciano; Parker, William; Parkes, Christopher; Passaleva, Giovanni; Pastore, Alessandra; Patel, Girish; Patel, Mitesh; Patrignani, Claudia; Pearce, Alex; Pellegrino, Antonio; Penso, Gianni; Pepe Altarelli, Monica; Perazzini, Stefano; Perret, Pascal; Pescatore, Luca; Petridis, Konstantinos; Petrolini, Alessandro; Petrov, Aleksandr; Petruzzo, Marco; Picatoste Olloqui, Eduardo; Pietrzyk, Boleslaw; Pikies, Malgorzata; Pinci, Davide; Pistone, Alessandro; Piucci, Alessio; Playfer, Stephen; Plo Casasus, Maximo; Poikela, Tuomas; Polci, Francesco; Poluektov, Anton; Polyakov, Ivan; Polycarpo, Erica; Pomery, Gabriela Johanna; Popov, Alexander; Popov, Dmitry; Popovici, Bogdan; Poslavskii, Stanislav; Potterat, Cédric; Price, Eugenia; Price, Joseph David; Prisciandaro, Jessica; Pritchard, Adrian; Prouve, Claire; Pugatch, Valery; Puig Navarro, Albert; Punzi, Giovanni; Qian, Wenbin; Quagliani, Renato; Rachwal, Bartolomiej; Rademacker, Jonas; Rama, Matteo; Ramos Pernas, Miguel; Rangel, Murilo; Raniuk, Iurii; Raven, Gerhard; Redi, Federico; Reichert, Stefanie; dos Reis, Alberto; Remon Alepuz, Clara; Renaudin, Victor; Ricciardi, Stefania; Richards, Sophie; Rihl, Mariana; Rinnert, Kurt; Rives Molina, Vicente; Robbe, Patrick; Rodrigues, Ana Barbara; Rodrigues, Eduardo; Rodriguez Lopez, Jairo Alexis; Rodriguez Perez, Pablo; Rogozhnikov, Alexey; Roiser, Stefan; Romanovskiy, Vladimir; Romero Vidal, Antonio; Ronayne, John William; Rotondo, Marcello; Rudolph, Matthew Scott; Ruf, Thomas; Ruiz Valls, Pablo; Saborido Silva, Juan Jose; Sadykhov, Elnur; Sagidova, Naylya; Saitta, Biagio; Salustino Guimaraes, Valdir; Sanchez Mayordomo, Carlos; Sanmartin Sedes, Brais; Santacesaria, Roberta; Santamarina Rios, Cibran; Santimaria, Marco; Santovetti, Emanuele; Sarti, Alessio; Satriano, Celestina; Satta, Alessia; Saunders, Daniel Martin; Savrina, Darya; Schael, Stefan; Schellenberg, Margarete; Schiller, Manuel; Schindler, Heinrich; Schlupp, Maximilian; Schmelling, Michael; Schmelzer, Timon; Schmidt, Burkhard; Schneider, Olivier; Schopper, Andreas; Schubert, Konstantin; Schubiger, Maxime; Schune, Marie Helene; Schwemmer, Rainer; Sciascia, Barbara; Sciubba, Adalberto; Semennikov, Alexander; Sergi, Antonino; Serra, Nicola; Serrano, Justine; Sestini, Lorenzo; Seyfert, Paul; Shapkin, Mikhail; Shapoval, Illya; Shcheglov, Yury; Shears, Tara; Shekhtman, Lev; Shevchenko, Vladimir; Shires, Alexander; Siddi, Benedetto Gianluca; Silva Coutinho, Rafael; Silva de Oliveira, Luiz Gustavo; Simi, Gabriele; Simone, Saverio; Sirendi, Marek; Skidmore, Nicola; Skwarnicki, Tomasz; Smith, Eluned; Smith, Iwan Thomas; Smith, Jackson; Smith, Mark; Snoek, Hella; Sokoloff, Michael; Soler, Paul; Souza De Paula, Bruno; Spaan, Bernhard; Spradlin, Patrick; Sridharan, Srikanth; Stagni, Federico; Stahl, Marian; Stahl, Sascha; Stefko, Pavol; Stefkova, Slavorima; Steinkamp, Olaf; Stemmle, Simon; Stenyakin, Oleg; Stevenson, Scott; Stoica, Sabin; Stone, Sheldon; Storaci, Barbara; Stracka, Simone; Straticiuc, Mihai; Straumann, Ulrich; Sun, Liang; Sutcliffe, William; Swientek, Krzysztof; Syropoulos, Vasileios; Szczekowski, Marek; Szumlak, Tomasz; T'Jampens, Stephane; Tayduganov, Andrey; Tekampe, Tobias; Tellarini, Giulia; Teubert, Frederic; Thomas, Eric; van Tilburg, Jeroen; Tilley, Matthew James; Tisserand, Vincent; Tobin, Mark; Tolk, Siim; Tomassetti, Luca; Tonelli, Diego; Topp-Joergensen, Stig; Toriello, Francis; Tournefier, Edwige; Tourneur, Stephane; Trabelsi, Karim; Traill, Murdo; Tran, Minh Tâm; Tresch, Marco; Trisovic, Ana; Tsaregorodtsev, Andrei; Tsopelas, Panagiotis; Tully, Alison; Tuning, Niels; Ukleja, Artur; Ustyuzhanin, Andrey; Uwer, Ulrich; Vacca, Claudia; Vagnoni, Vincenzo; Valassi, Andrea; Valat, Sebastien; Valenti, Giovanni; Vallier, Alexis; Vazquez Gomez, Ricardo; Vazquez Regueiro, Pablo; Vecchi, Stefania; van Veghel, Maarten; Velthuis, Jaap; Veltri, Michele; Veneziano, Giovanni; Venkateswaran, Aravindhan; Vernet, Maxime; Vesterinen, Mika; Viaud, Benoit; Vieira, Daniel; Vieites Diaz, Maria; Vilasis-Cardona, Xavier; Volkov, Vladimir; Vollhardt, Achim; Voneki, Balazs; Vorobyev, Alexey; Vorobyev, Vitaly; Voß, Christian; de Vries, Jacco; Vázquez Sierra, Carlos; Waldi, Roland; Wallace, Charlotte; Wallace, Ronan; Walsh, John; Wang, Jianchun; Ward, David; Wark, Heather Mckenzie; Watson, Nigel; Websdale, David; Weiden, Andreas; Whitehead, Mark; Wicht, Jean; Wilkinson, Guy; Wilkinson, Michael; Williams, Mark Richard James; Williams, Matthew; Williams, Mike; Williams, Timothy; Wilson, Fergus; Wimberley, Jack; Wishahi, Julian; Wislicki, Wojciech; Witek, Mariusz; Wormser, Guy; Wotton, Stephen; Wraight, Kenneth; Wright, Simon; Wyllie, Kenneth; Xie, Yuehong; Xing, Zhou; Xu, Zhirui; Yang, Zhenwei; Yin, Hang; Yu, Jiesheng; Yuan, Xuhao; Yushchenko, Oleg; Zarebski, Kristian Alexander; Zavertyaev, Mikhail; Zhang, Liming; Zhang, Yanxi; Zhang, Yu; Zhelezov, Alexey; Zheng, Yangheng; Zhokhov, Anatoly; Zhu, Xianglei; Zhukov, Valery; Zucchelli, Stefano

    2017-01-30

    Differences in the behaviour of matter and antimatter have been observed in $K$ and $B$ meson decays, but not yet in any baryon decay. Such differences are associated with the non-invariance of fundamental interactions under the combined charge-conjugation and parity transformations, known as $C\\!P$ violation. Using data from the LHCb experiment at the Large Hadron Collider, a search is made for $C\\!P$-violating asymmetries in the decay angle distributions of $\\Lambda^0_b$ baryons decaying to $p\\pi^-\\pi^+\\pi^-$ and $p\\pi^-K^+K^-$ final states. These four-body hadronic decays are a promising place to search for sources of $C\\!P$ violation both within and beyond the Standard Model of particle physics. We find evidence for $C\\!P$ violation in $\\Lambda^0_b$ to $p\\pi^-\\pi^+\\pi^-$ decays with a statistical significance corresponding to 3.3 standard deviations including systematic uncertainties. This represents the first evidence for $C\\!P$ violation in the baryon sector.

  4. Measurement of matter-antimatter differences in beauty baryon decays at LHCb

    CERN Multimedia

    Merli, Andrea

    2017-01-01

    Differences in the behaviour of matter and antimatter have been observed in $K$ and $B$ meson decays, but not yet in any baryon decay. Such differences are associated with the non-invariance of fundamental interactions under the combined charge-conjugation and parity transformations, known as $C\\!P$ violation. Using data from the LHCb experiment at the Large Hadron Collider, a search is made for $C\\!P$-violating asymmetries in the decay angle distributions of $\\Lambda_b^0$ baryons decaying to $p\\pi^-\\pi^+\\pi^-$ and $p\\pi^-K^+K^-m$ final states. These four-body hadronic decays are a promising place to search for sources of $C\\!P$ violation both within and beyond the Standard Model of particle physics. We find evidence for $C\\!P$ violation in $\\Lambda_b^0$ to $p\\pi^-\\pi^+\\pi^-$ decays with a statistical significance corresponding to 3.3 standard deviations including systematic uncertainties. This represents the first evidence for $C\\!P$ violation in the baryon sector.

  5. QCD equation of state of hot deconfined matter at finite baryon density. A quasiparticle perspective

    International Nuclear Information System (INIS)

    Bluhm, Marcus

    2008-01-01

    The quasiparticle model, based on quark and gluon degrees of freedom, has been developed for the description of the thermodynamics of a hot plasma of strongly interacting matter which is of enormous relevance in astrophysics, cosmology and for relativistic heavy-ion collisions as well. In the present work, this phenomenological model is extended into the realm of imaginary chemical potential and towards including, in general, different and independent quark flavour chemical potentials. In this way, nonzero net baryon-density effects in the equation of state are selfconsistently attainable. Furthermore, a chain of approximations based on formal mathematical manipulations is presented which outlines the connection of the quasiparticle model with the underlying gauge field theory of strong interactions, QCD, putting the model on firmer ground. The applicability of the model to extrapolate the equation of state known from lattice QCD at zero baryon density to nonzero baryon densities is shown. In addition, the ability of the model to extrapolate results to the chiral limit and to asymptotically large temperatures is illustrated by confrontation with available first-principle lattice QCD results. Basing on these successful comparisons supporting the idea that the hot deconfined phase can be described in a consistent picture by dressed quark and gluon degrees of freedom, a reliable QCD equation of state is constructed and baryon-density effects are examined, also along isentropic evolutionary paths. Scaling properties of the equation of state with fundamental QCD parameters such as the number of active quark flavour degrees of freedom, the entering quark mass parameters or the numerical value of the deconfinement transition temperature are discussed, and the robustness of the equation of state in the regions of small and large energy densities is shown. Uncertainties arising in the transition region are taken into account by constructing a family of equations of state

  6. Sharing but not caring. Dark matter and the baryon asymmetry of the universe

    Energy Technology Data Exchange (ETDEWEB)

    Bernal, Nicolas [Universidad Estadual Paulista, Sao Paulo (Brazil). Inst. de Fisica Teorica; Austrian Academy of Sciences, Vienna (Austria). Inst. of High Energy Physics; Fong, Chee Sheng [Sao Paulo Univ. (Brazil). Inst. de Fisica; Fonseca, Nayara [Sao Paulo Univ. (Brazil). Inst. de Fisica; Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2016-09-15

    We consider scenarios where Dark Matter (DM) particles carry baryon and/or lepton numbers, which can be defined if there exist operators connecting the dark to the visible sector. As a result, the DM fields become intimately linked to the Standard Model (SM) ones and can be maximally asymmetric just like the ordinary matter. In particular, we discuss minimal scenarios where the DM is a complex scalar or a Dirac fermion coupled to operators with nonzero baryon and/or lepton numbers, and that consist of only SM fields. We consider an initial asymmetry stored in either the SM or the DM sector; the main role of these operators is to properly share the asymmetry between the two sectors, in accordance with observations. After the chemical decoupling, the DM and SM sectors do not care about each other as there is only an ineffective communication between them. Once the DM mass is specified, the Wilson coefficients of these operators are fixed by the requirement of the correct transfer of the asymmetry. We study the phenomenology of this framework at colliders, direct detection and indirect detection experiments. In particular, the LHC phenomenology is very rich and can be tested in different channels such as the two same-sign leptons with two jets, monojet and monojet with a monolepton.

  7. Sharing but not caring: dark matter and the baryon asymmetry of the universe

    Energy Technology Data Exchange (ETDEWEB)

    Bernal, Nicolás [ICTP South American Institute for Fundamental Research, Instituto de Física Teórica, Universidade Estadual Paulista,R. Dr. Bento Teobaldo Ferraz 271, 01140-070 São Paulo (Brazil); Institute of High Energy Physics, Austrian Academy of Sciences,Nikolsdorfer Gasse 18, 1050 Vienna (Austria); Fong, Chee Sheng [Instituto de Física, Universidade de São Paulo,Rua do Matão 1371, 05508-090 São Paulo (Brazil); Fonseca, Nayara [Instituto de Física, Universidade de São Paulo,Rua do Matão 1371, 05508-090 São Paulo (Brazil); DESY,Notkestraße 85, 22607 Hamburg (Germany)

    2016-09-02

    We consider scenarios where Dark Matter (DM) particles carry baryon and/or lepton numbers, which can be defined if there exist operators connecting the dark to the visible sector. As a result, the DM fields become intimately linked to the Standard Model (SM) ones and can be maximally asymmetric just like the ordinary matter. In particular, we discuss minimal scenarios where the DM is a complex scalar or a Dirac fermion coupled to operators with nonzero baryon and/or lepton numbers, and that consist of only SM fields. We consider an initial asymmetry stored in either the SM or the DM sector; the main role of these operators is to properly share the asymmetry between the two sectors, in accordance with observations. After the chemical decoupling, the DM and SM sectors do not care about each other as there is only an ineffective communication between them. Once the DM mass is specified, the Wilson coefficients of these operators are fixed by the requirement of the correct transfer of the asymmetry. We study the phenomenology of this framework at colliders, direct detection and indirect detection experiments. In particular, the LHC phenomenology is very rich and can be tested in different channels such as the two same-sign leptons with two jets, monojet and monojet with a monolepton.

  8. Dark matter component decaying after recombination: Sensitivity to baryon acoustic oscillation and redshift space distortion probes

    Science.gov (United States)

    Chudaykin, A.; Gorbunov, D.; Tkachev, I.

    2018-04-01

    It has been recently suggested [1] that a subdominant fraction of dark matter decaying after recombination may alleviate tension between high-redshift (CMB anisotropy) and low-redshift (Hubble constant, cluster counts) measurements. In this report, we continue our previous study [2] of the decaying dark matter (DDM) model adding all available recent baryon acoustic oscillation (BAO) and redshift space distortions (RSD) measurements. We find that the BAO/RSD measurements generically prefer the standard Λ CDM and combined with other cosmological measurements impose an upper limit on the DDM fraction at the level of ˜5 %, strengthening by a factor of 1.5 limits obtained in [2] mostly from CMB data. However, the numbers vary from one analysis to other based on the same Baryon Oscillation Spectroscopic Survey (BOSS) Data Release 12 (DR12) galaxy sample. Overall, the model with a few percent DDM fraction provides a better fit to the combined cosmological data as compared to the Λ CDM : the cluster counting and direct measurements of the Hubble parameter are responsible for that. The improvement can be as large as 1.5 σ and grows to 3.3 σ when the CMB lensing power amplitude AL is introduced as a free fitting parameter.

  9. Sharing but not caring. Dark matter and the baryon asymmetry of the universe

    International Nuclear Information System (INIS)

    Bernal, Nicolas

    2016-09-01

    We consider scenarios where Dark Matter (DM) particles carry baryon and/or lepton numbers, which can be defined if there exist operators connecting the dark to the visible sector. As a result, the DM fields become intimately linked to the Standard Model (SM) ones and can be maximally asymmetric just like the ordinary matter. In particular, we discuss minimal scenarios where the DM is a complex scalar or a Dirac fermion coupled to operators with nonzero baryon and/or lepton numbers, and that consist of only SM fields. We consider an initial asymmetry stored in either the SM or the DM sector; the main role of these operators is to properly share the asymmetry between the two sectors, in accordance with observations. After the chemical decoupling, the DM and SM sectors do not care about each other as there is only an ineffective communication between them. Once the DM mass is specified, the Wilson coefficients of these operators are fixed by the requirement of the correct transfer of the asymmetry. We study the phenomenology of this framework at colliders, direct detection and indirect detection experiments. In particular, the LHC phenomenology is very rich and can be tested in different channels such as the two same-sign leptons with two jets, monojet and monojet with a monolepton.

  10. Dark matter annihilation in the milky way galaxy: effects of baryonic compression.

    Science.gov (United States)

    Prada, F; Klypin, A; Flix, J; Martínez, M; Simonneau, E

    2004-12-10

    If the dark matter (DM), which is considered to constitute most of the mass of galaxies, is made of supersymmetric particles, the central region of our Galaxy should emit gamma rays produced by their annihilation. We use detailed models of the Milky Way to make accurate estimates of continuum gamma-ray fluxes. We argue that the most important effect, which was previously neglected, is the compression of the dark matter due to the infall of baryons to the galactic center: it boosts the expected signal by a factor 1000. To illustrate this effect, we computed the expected gamma fluxes in the minimal supergravity scenario. Our models predict that the signal could be detected at high confidence levels by imaging atmospheric C erenkov telescopes assuming that neutralinos make up most of the DM in the Universe.

  11. Analysis of the doubly heavy baryons in the nuclear matter with the QCD sum rules

    International Nuclear Information System (INIS)

    Wang, Zhi-Gang

    2012-01-01

    In this article, we study the doubly heavy baryon states Ξ cc , Ω cc , Ξ bb and Ω bb in the nuclear matter using the QCD sum rules, and derive three coupled QCD sum rules for the masses, vector self-energies and pole residues. The predictions for the mass-shifts in the nuclear matter ΔM Ξ cc =-1.11simGeV, ΔM Ω cc =-0.33∝GeV, ΔM Ξ bb =-3.37∝GeV and ΔM Ω bb =-1.05∝GeV can be confronted with experimental data in the future. (orig.)

  12. Diffusion in condensed matter methods, materials, models

    CERN Document Server

    Kärger, Jörg

    2005-01-01

    Diffusion as the process of particle transport due to stochastic movement is a phenomenon of crucial relevance for a large variety of processes and materials. This comprehensive, handbook- style survey of diffusion in condensed matter gives detailed insight into diffusion as the process of particle transport due to stochastic movement. Leading experts in the field describe in 23 chapters the different aspects of diffusion, covering microscopic and macroscopic experimental techniques and exemplary results for various classes of solids, liquids and interfaces as well as several theoretical concepts and models. Students and scientists in physics, chemistry, materials science, and biology will benefit from this detailed compilation.

  13. DISSECTING GALAXY FORMATION. II. COMPARING SUBSTRUCTURE IN PURE DARK MATTER AND BARYONIC MODELS

    International Nuclear Information System (INIS)

    Romano-Diaz, Emilio; Shlosman, Isaac; Heller, Clayton; Hoffman, Yehuda

    2010-01-01

    We compare the substructure evolution in pure dark matter (DM) halos with those in the presence of baryons, hereafter PDM and BDM models, respectively. The prime halos have been analyzed in the previous work. Models have been evolved from identical initial conditions which have been constructed by means of the constrained realization method. The BDM model includes star formation and feedback from stellar evolution onto the gas. A comprehensive catalog of subhalo populations has been compiled and individual and statistical properties of subhalos analyzed, including their orbital differences. We find that subhalo population mass functions in PDM and BDM are consistent with a single power law, M α sbh , for each of the models in the mass range of ∼2 x 10 8 M sun -2 x 10 11 M sun . However, we detect a nonnegligible shift between these functions, the time-averaged α ∼ -0.86 for the PDM and -0.98 for the BDM models. Overall, α appears to be a nearly constant in time, with variations of ±15%. Second, we find that the radial mass distribution of subhalo populations can be approximated by a power law, R γ sbh with a steepening that occurs at the radius of a maximal circular velocity, R vmax , in the prime halos. Here we find that γ sbh ∼ -1.5 for the PDM and -1 for the BDM models, when averaged over time inside R vmax . The slope is steeper outside this region and approaches -3. We detect little spatial bias (less than 10%) between the subhalo populations and the DM distribution of the main halos. Also, the subhalo population exhibits much less triaxiality in the presence of baryons, in tandem with the shape of the prime halo. Finally, we find that, counter-intuitively, the BDM population is depleted at a faster rate than the PDM one within the central 30 kpc of the prime halo. The reason for this is that although the baryons provide a substantial glue to the subhalos, the main halo exhibits the same trend. This assures a more efficient tidal disruption of the

  14. Constraints on baryonic dark matter in the Galactic halo and Local Group

    Science.gov (United States)

    Richstone, Douglas; Gould, Andrew; Guhathakurta, Puragra; Flynn, Chris

    1992-01-01

    A four-color method and deep CCD data are used to search for very faint metal-poor stars in the direction of the south Galactic pole. The results make it possible to limit the contribution of ordinary old, metal-poor stars to the dynamical halo of the Galaxy or to the Local Group. The ratio of the mass of the halo to its ordinary starlight must be more than about 2000, unless the halo is very small. For the Local Group, this ratio is greater than about 400. If this local dark matter is baryonic, the process of compact-object formation must produce very few 'impurities' in the form of stars similar to those found in globular clusters. The expected number of unbound stars with MV not greater than 6 within 100 pc of the sun is less than 1 based on the present 90-percent upper limit to the Local Group starlight.

  15. Axino dark matter and baryon number asymmetry production by the Q-ball decay in gauge mediation

    Energy Technology Data Exchange (ETDEWEB)

    Kasuya, Shinta [Department of Mathematics and Physics, Kanagawa University, Kanagawa 259-1293 (Japan); Kawakami, Etsuko; Kawasaki, Masahiro, E-mail: kasuya@kanagawa-u.ac.jp, E-mail: kwkm@icrr.u-tokyo.ac.jp, E-mail: kawasaki@icrr.u-tokyo.ac.jp [Institute for Cosmic Ray Research, University of Tokyo, Chiba 277-8582 (Japan)

    2016-03-01

    We investigate the Q-ball decay into the axino dark matter in the gauge-mediated supersymmetry breaking. In our scenario, the Q ball decays mainly into nucleons and partially into axinos to account respectively for the baryon asymmetry and the dark matter of the universe. The Q ball decays well before the big bang nucleosynthesis so that it is not affected by the decay. We show the region of the parameters which realizes this scenario.

  16. Anisotropic diffusion within human white matter

    International Nuclear Information System (INIS)

    Chenevert, T.L.; Brunberg, J.A.; Pipe, J.G.

    1990-01-01

    This paper reports on measurements performed to assess the impact of fiber orientation on the apparent diffusion coefficient of human white matter in vivo. Orthogonal section selection pulses and strong motion sensitization gradient pulses were used for localized diffusion measurement along an anteroposteriorly oriented 1 x 1 cm tissue column in the left cerebral hemisphere. This region was selected since white matter fiber orientations are reasonably well defined. Independent acquisitions with motion sensitivity along anteroposterior and right-left directions allowed study of diffusion anisotropy. Motion artifacts were minimized by magnitude summation after one-dimensional Fourier transform of frequency-encoded echoes; consequently, cardiac gating was not required. Five normal volunteers were studied on a 1.5-T clinical MR system

  17. Cosmological perturbation theory for baryons and dark matter: One-loop corrections in the renormalized perturbation theory framework

    International Nuclear Information System (INIS)

    Somogyi, Gabor; Smith, Robert E.

    2010-01-01

    We generalize the renormalized perturbation theory (RPT) formalism of Crocce and Scoccimarro [M. Crocce and R. Scoccimarro, Phys. Rev. D 73, 063519 (2006)] to deal with multiple fluids in the Universe and here we present the complete calculations up to the one-loop level in the RPT. We apply this approach to the problem of following the nonlinear evolution of baryon and cold dark matter (CDM) perturbations, evolving from the distinct sets of initial conditions, from the high redshift post-recombination Universe right through to the present day. In current theoretical and numerical models of structure formation, it is standard practice to treat baryons and CDM as an effective single matter fluid--the so-called dark matter only modeling. In this approximation, one uses a weighed sum of late-time baryon and CDM transfer functions to set initial mass fluctuations. In this paper we explore whether this approach can be employed for high precision modeling of structure formation. We show that, even if we only follow the linear evolution, there is a large-scale scale-dependent bias between baryons and CDM for the currently favored WMAP5 ΛCDM model. This time evolving bias is significant (>1%) until the present day, when it is driven towards unity through gravitational relaxation processes. Using the RPT formalism we test this approximation in the nonlinear regime. We show that the nonlinear CDM power spectrum in the two-component fluid differs from that obtained from an effective mean-mass one-component fluid by ∼3% on scales of order k∼0.05h Mpc -1 at z=10, and by ∼0.5% at z=0. However, for the case of the nonlinear evolution of the baryons the situation is worse and we find that the power spectrum is suppressed, relative to the total matter, by ∼15% on scales k∼0.05h Mpc -1 at z=10, and by ∼3%-5% at z=0. Importantly, besides the suppression of the spectrum, the baryonic acoustic oscillation (BAO) features are amplified for baryon and slightly damped for CDM

  18. Cosmological perturbation theory for baryons and dark matter: One-loop corrections in the renormalized perturbation theory framework

    Science.gov (United States)

    Somogyi, Gábor; Smith, Robert E.

    2010-01-01

    We generalize the renormalized perturbation theory (RPT) formalism of Crocce and Scoccimarro [M. Crocce and R. Scoccimarro, Phys. Rev. DPRVDAQ1550-7998 73, 063519 (2006)10.1103/PhysRevD.73.063519] to deal with multiple fluids in the Universe and here we present the complete calculations up to the one-loop level in the RPT. We apply this approach to the problem of following the nonlinear evolution of baryon and cold dark matter (CDM) perturbations, evolving from the distinct sets of initial conditions, from the high redshift post-recombination Universe right through to the present day. In current theoretical and numerical models of structure formation, it is standard practice to treat baryons and CDM as an effective single matter fluid—the so-called dark matter only modeling. In this approximation, one uses a weighed sum of late-time baryon and CDM transfer functions to set initial mass fluctuations. In this paper we explore whether this approach can be employed for high precision modeling of structure formation. We show that, even if we only follow the linear evolution, there is a large-scale scale-dependent bias between baryons and CDM for the currently favored WMAP5 ΛCDM model. This time evolving bias is significant (>1%) until the present day, when it is driven towards unity through gravitational relaxation processes. Using the RPT formalism we test this approximation in the nonlinear regime. We show that the nonlinear CDM power spectrum in the two-component fluid differs from that obtained from an effective mean-mass one-component fluid by ˜3% on scales of order k˜0.05hMpc-1 at z=10, and by ˜0.5% at z=0. However, for the case of the nonlinear evolution of the baryons the situation is worse and we find that the power spectrum is suppressed, relative to the total matter, by ˜15% on scales k˜0.05hMpc-1 at z=10, and by ˜3%-5% at z=0. Importantly, besides the suppression of the spectrum, the baryonic acoustic oscillation (BAO) features are amplified for

  19. Cosmological perturbation theory for baryons and dark matter I. One-loop corrections in the RPT framework

    Energy Technology Data Exchange (ETDEWEB)

    Somogyi, Gabor [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Zurich Univ. (Switzerland). Inst. for Theoretical Physics; Smith, Robert E. [Zurich Univ. (Switzerland). Inst. for Theoretical Physics

    2009-10-15

    We generalize the ''renormalized'' perturbation theory (RPT) formalism of M. Crocce and R. Scoccimarro (2006) to deal with multiple fluids in the Universe and here we present the complete calculations up to the one-loop level in the RPT. We apply this approach to the problem of following the nonlinear evolution of baryon and cold dark matter (CDM) perturbations, evolving from the distinct sets of initial conditions, from the high redshift post-recombination Universe right through to the present day. In current theoretical and numerical models of structure formation, it is standard practice to treat baryons and CDM as an effective single matter fluid - the so called dark matter only modeling. In this approximation, one uses a weighed sum of late time baryon and CDM transfer functions to set initial mass fluctuations. In this paper we explore whether this approach can be employed for high precision modeling of structure formation. We show that, even if we only follow the linear evolution, there is a large-scale scale-dependent bias between baryons and CDM for the currently favored WMAP5 {lambda}CDM model. This time evolving bias is significant (> 1%) until the present day, when it is driven towards unity through gravitational relaxation processes. Using the RPT formalism we test this approximation in the non-linear regime. We show that the non-linear CDM power spectrum in the 2-component fluid differs from that obtained from an effective mean-mass 1-component fluid by {proportional_to} 3% on scales of order k {proportional_to} 0.05 h Mpc{sup -1} at z = 10, and by {proportional_to} 0.5% at z = 0. However, for the case of the non-linear evolution of the baryons the situation is worse and we find that the power spectrum is suppressed, relative to the total matter, by {proportional_to} 15% on scales k {proportional_to} 0.05 hMpc{sup -1} at z = 10, and by {proportional_to} 3 - 5% at z = 0. Importantly, besides the suppression of the spectrum, the

  20. Properties of ΣQ*, ΞQ* and ΩQ* heavy baryons in cold nuclear matter

    Science.gov (United States)

    Azizi, K.; Er, N.

    2018-02-01

    The in-medium properties of the heavy spin-3/2 ΣQ*, ΞQ* and ΩQ* baryons with Q being b or c quark are investigated. The shifts in some spectroscopic parameters of these particles due to the saturated cold nuclear matter are calculated. The variations of those parameters with respect to the changes in the density of the cold nuclear medium are studied, as well. It is observed that the parameters of ΣQ* baryons are considerably affected by the nuclear matter compared to the ΞQ* and ΩQ* particles that roughly do not see the medium. The results obtained may be used in analyses of the data to be provided by the in-medium experiments like PANDA.

  1. Radiation hardness investigation of avalanche photodiodes for the Projectile Spectator Detector readout at the Compressed Baryonic Matter experiment

    Czech Academy of Sciences Publication Activity Database

    Kushpil, Vasilij; Mikhaylov, Vasily; Kushpil, Svetlana; Tlustý, Pavel; Svoboda, Ondřej; Kugler, Andrej

    2015-01-01

    Roč. 787, JUL (2015), s. 117-120 ISSN 0168-9002 R&D Projects: GA MŠk LG12007; GA MŠk LG14004; GA MŠk(CZ) LM2011019 Institutional support: RVO:61389005 Keywords : avalanche photodiodes * single protons detection * radiation hardness * neutron irradiation tests * compressed Baryonic Matter experiment * Projectile Spectator Detector Subject RIV: BG - Nuclear, Atomic and Molecular Physics , Colliders Impact factor: 1.200, year: 2015

  2. Rapidity dependence of thermal dileptons resulting from hadronizing quark-gluon matter with finite baryon charge

    International Nuclear Information System (INIS)

    Kaempfer, B.; Technische Univ. Dresden; Pavlenko, O.P.; AN Ukrainskoj SSR, Kiev; Gorenstein, M.I.; Peshier, A.; Soff, G.

    1994-07-01

    The influence of a non-vanishing baryon charge on the rapidity distribution of dileptons produced in ultrarelativistic heavy-ion collisions is studied. We employ a frozen motion model with scaling invariant expansion of the hadronizing quark-gluon plasma as well as a realistic rapidity distribution of secondary particles (i.e., pions and baryons) expected for RHIC energies. We find a considerable suppression of the dilepton production yield at large rapidities due to the finite baryon density. To discriminate the thermal dileptons from Drell-Yan background we propose to utilize the dilepton yield scaled suitably by the pion multiplicity as function of rapidity. (orig.)

  3. Leptogenesis as an origin of hot dark matter and baryon asymmetry in the E6 inspired SUSY models

    Science.gov (United States)

    Nevzorov, R.

    2018-04-01

    We explore leptogenesis within the E6 inspired U (1) extension of the MSSM in which exact custodial symmetry forbids tree-level flavour-changing transitions and the most dangerous baryon and lepton number violating operators. This supersymmetric (SUSY) model involves extra exotic matter beyond the MSSM. In the simplest phenomenologically viable scenarios the lightest exotic fermions are neutral and stable. These states should be substantially lighter than 1eV forming hot dark matter in the Universe. The low-energy effective Lagrangian of the SUSY model under consideration possesses an approximate global U(1)E symmetry associated with the exotic states. The U(1)E symmetry is explicitly broken because of the interactions between the right-handed neutrino superfields and exotic matter supermultiplets. As a consequence the decays of the lightest right-handed neutrino/sneutrino give rise to both U(1)E and U(1) B - L asymmetries. When all right-handed neutrino/sneutrino are relatively light ∼106-107GeV the appropriate amount of the baryon asymmetry can be induced via these decays if the Yukawa couplings of the lightest right-handed neutrino superfields to the exotic matter supermultiplets vary between ∼10-4-10-3.

  4. QCD inequalities for the nucleon mass and the free energy of baryonic matter.

    Science.gov (United States)

    Cohen, Thomas D

    2003-07-18

    The positivity of the integrand of certain Euclidean space functional integrals for two flavor QCD with degenerate quark masses implies that the free energy per unit volume for QCD with a baryon chemical potential mu(B) (and zero isospin chemical potential) is greater than the free energy with an isospin chemical potential mu(I)=(2 mu(B)/N(c)) (and zero baryon chemical potential). The same result applies to QCD with any number of heavy flavors in addition to the two light flavors so long as the chemical potential is understood as applying to the light quark contributions to the baryon number. This relation implies a bound on the nucleon mass: there exists a particle X in QCD (presumably the pion) such that M(N)> or =(N(c) m(X)/2 I(X)) where m(X) is the mass of the particle and I(X) is its isospin.

  5. Dark matter direct detection signals inferred from a cosmological N-body simulation with baryons

    International Nuclear Information System (INIS)

    Ling, F.-S.; Nezri, E.; Athanassoula, E.; Teyssier, R.

    2010-01-01

    We extract at redshift z = 0 a Milky Way sized object including gas, stars and dark matter (DM) from a recent, high-resolution cosmological N-body simulation with baryons. Its resolution is sufficient to witness the formation of a rotating disk and bulge at the center of the halo potential, therefore providing a realistic description of the birth and the evolution of galactic structures in the ΛCDM cosmology paradigm. The phase-space structure of the central galaxy reveals that, throughout a thick region, the dark halo is co-rotating on average with the stellar disk. At the Earth's location, the rotating component, sometimes called dark disk in the literature, is characterized by a minimum lag velocity v lag ≅ 75 km/s, in which case it contributes to around 25% of the total DM local density, whose value is ρ DM ≅ 0.37GeV/cm 3 . The velocity distributions also show strong deviations from pure Gaussian and Maxwellian distributions, with a sharper drop of the high velocity tail. We give a detailed study of the impact of these features on the predictions for DM signals in direct detection experiments. In particular, the question of whether the modulation signal observed by DAMA is or is not excluded by limits set by other experiments (CDMS, XENON and CRESST...) is re-analyzed and compared to the case of a standard Maxwellian halo. We consider spin-independent interactions for both the elastic and the inelastic scattering scenarios. For the first time, we calculate the allowed regions for DAMA and the exclusion limits of other null experiments directly from the velocity distributions found in the simulation. We then compare these results with the predictions of various analytical distributions. We find that the compatibility between DAMA and the other experiments is improved. In the elastic scenario, the DAMA modulation signal is slightly enhanced in the so-called channeling region, as a result of several effects that include a departure from a Maxwellian

  6. Searching for baryons

    International Nuclear Information System (INIS)

    Majumdar, Subhabrata

    2015-01-01

    The current precision cosmological measurements, in agreement with big bang nucleosynthesis studies, tell us that approximately 95 percent of the Universe is 'dark' and only 5 percent of the Universe is 'visible' which comprises of baryons. However, observations reveal only a small fraction of this baryon budget. A key cosmological question arises as to 'where are these missing baryons?'. Simulations and past observations suggest that some of these are in the diffuse cosmic web. Recently, they have been observed, and speculated, to be hiding in the outskirts of massive halos, from Milky Way type galaxies to clusters. Upcoming surveys have the potential to unravel the mystery of the missing baryons. (author)

  7. Modified holographic Ricci dark energy coupled to interacting dark matter and a non-interacting baryonic component

    Energy Technology Data Exchange (ETDEWEB)

    Chimento, Luis P.; Richarte, Martin G. [Universidad de Buenos Aires, IFIBA, CONICET, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina); Forte, Monica [Universidad de Buenos Aires, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina)

    2013-01-15

    We examine a Friedmann-Robertson-Walker universe filled with interacting dark matter, modified holographic Ricci dark energy (MHRDE), and a decoupled baryonic component. The estimations of the cosmic parameters with Hubble data lead to an age of the universe of 13.17 Gyr and show that the MHRDE is free from the cosmic-age problem at low redshift (0{<=}z{<=}2) in contrast to holographic Ricci dark energy (HRDE) case. We constrain the parameters with the Union2 data set and contrast with the Hubble data. We also study the behavior of dark energy at early times by taking into account the severe bounds found at recombination era and/or at big bang nucleosynthesis. The inclusion of a non-interacting baryonic matter forces that the amount of dark energy at z{sub t} {proportional_to} O(1) changes abruptly implying that {Omega} {sub x} (z {approx_equal}1100)=0.03, so the bounds reported by the forecast of Planck and CMBPol experiments are more favored for the MHRDE model than in the case of HRDE cutoff. For the former model, we also find that at high redshift the fraction of dark energy varies from 0.006 to 0.002, then the amount of {Omega} {sub x} at the big bang nucleosynthesis era does not disturb the observed helium abundance in the universe provided that the bound {Omega} {sub x} (z {approx_equal}10 {sup 10}) <0.21 is hold. (orig.)

  8. Supercluster simulations: impact of baryons on the matter power spectrum and weak lensing forecasts for Super-CLASS

    Science.gov (United States)

    Peters, Aaron; Brown, Michael L.; Kay, Scott T.; Barnes, David J.

    2018-03-01

    We use a combination of full hydrodynamic and dark matter only simulations to investigate the effect that supercluster environments and baryonic physics have on the matter power spectrum, by re-simulating a sample of supercluster sub-volumes. On large scales we find that the matter power spectrum measured from our supercluster sample has at least twice as much power as that measured from our random sample. Our investigation of the effect of baryonic physics on the matter power spectrum is found to be in agreement with previous studies and is weaker than the selection effect over the majority of scales. In addition, we investigate the effect of targeting a cosmologically non-representative, supercluster region of the sky on the weak lensing shear power spectrum. We do this by generating shear and convergence maps using a line-of-sight integration technique, which intercepts our random and supercluster sub-volumes. We find the convergence power spectrum measured from our supercluster sample has a larger amplitude than that measured from the random sample at all scales. We frame our results within the context of the Super-CLuster Assisted Shear Survey (Super-CLASS), which aims to measure the cosmic shear signal in the radio band by targeting a region of the sky that contains five Abell clusters. Assuming the Super-CLASS survey will have a source density of 1.5 galaxies arcmin-2, we forecast a detection significance of 2.7^{+1.5}_{-1.2}, which indicates that in the absence of systematics the Super-CLASS project could make a cosmic shear detection with radio data alone.

  9. Big Bang Nucleosynthesis: Impact of Nuclear Physics Uncertainties on Baryonic Matter Density

    International Nuclear Information System (INIS)

    Smith, Michael Scott; Roberts, Luke F.; Hix, William Raphael; Bruner, Blake D.; Kozub, R.L.; Tytler, David; Fuller, George M.; Lingerfelt, Eric J.; Nesaraja, Caroline D

    2008-01-01

    We performed new Big Bang Nucleosynthesis simulations with the bigbangonline.org suite of codes to determine, from the nuclear physics perspective, the highest achievable precision of the constraint on the baryon-to-photo ratio η given current observational uncertainties. We also performed sensitivity studies to determine the impact that particular nuclear physics measurements would have on the uncertainties of predicted abundances and on the η constraint.

  10. Big Bang Nucleosynthesis: Impact of Nuclear Physics Uncertainties on Baryonic Matter Density Constraints

    International Nuclear Information System (INIS)

    Smith, Michael S.; Roberts, Luke F.; Hix, W. Raphael; Bruner, Blake D.; Kozub, Raymond L.; Tytler, David; Fuller, George M.; Lingerfelt, Eric; Nesaraja, Caroline D.

    2008-01-01

    We performed new Big Bang Nucleosynthesis simulations with the bigbangonline.org suite of codes to determine, from the nuclear physics perspective, the highest achievable precision of the constraint on the baryon-to-photo ratio η given current observational uncertainties. We also performed sensitivity studies to determine the impact that particular nuclear physics measurements would have on the uncertainties of predicted abundances and on the η constraint

  11. Big Bang Nucleosynthesis: Impact of Nuclear Physics Uncertainties on Baryonic Matter Density Constraints

    International Nuclear Information System (INIS)

    Smith, Michael Scott; Bruner, Blake D; KOZUB, RAYMOND L.; Roberts, Luke F.; Tytler, David; Fuller, George M.; Lingerfelt, Eric; Hix, William Raphael; Nesaraja, Caroline D

    2008-01-01

    We ran new Big Bang Nucleosynthesis simulations with the bigbangonline.org suite of codes to determine, from the nuclear physics perspective, the highest achievable precision of the constraint on the baryon-to-photo ratio eta given current observational uncertainties. We also ran sensitivity studies to determine the impact that particular nuclear physics measurements would have on the uncertainties of predicted abundances and on the eta constraint

  12. Optimization of a transition radiation detector for the compressed baryonic matter experiment

    Energy Technology Data Exchange (ETDEWEB)

    Arend, Andreas

    2014-07-01

    The Transition Radiation Detector (TRD) of the compressed baryonic matter (CBM) experiment at FAIR has to provide electron-pion separation as well as charged-particle tracking. Within this work, thin and symmetric Multi-Wire Proportional Chambers (MWPCs) without additional drift region were proposed. the proposed prototypes feature a foil-based entrance window to minimize the material budget and to reduce the absorption probability of the generated TR photon. Based on the conceptual design of thin and symmetric MWPCs without drift region, multiple prototypes were constructed and their performance presented within this thesis. With the constructed prototypes of generations II and III the geometries of the wire and cathode planes were determined to be 4+4 mm and 5+5 mm. Based on the results of a performed test beam campaign in 2011 with this prototypes new prototypes of generation IV were manufactured and tested in a subsequent test beam campaign in 2012. Prototypes of different radiators were developed together with the MWPC prototypes. Along with regular foil radiators, foam-based radiator types made of polyethylene foam were utilized. Also radiators constructed in a sandwich design, which used different fiber materials confined with solid foam sheets, were used. For the prototypes without drift region, simulations of the electrostatic and mechanical properties were performed. The GARFIELD software package was used to simulate the electric field and to determine the resulting drift lines of the generated electrons. The mean gas amplification depending on the utilized gas and the applied anode voltage was simulated and the gas-gain homogeneity was verified. Since the thin foil-based entrance window experiences a deformation due to pressure differences inside and outside the MWPC, the variation on the gas gain depending on the deformation was simulated. The mechanical properties focusing on the stability of the entrance window was determined with a finiteelement

  13. Optimization of a transition radiation detector for the compressed baryonic matter experiment

    International Nuclear Information System (INIS)

    Arend, Andreas

    2014-01-01

    The Transition Radiation Detector (TRD) of the compressed baryonic matter (CBM) experiment at FAIR has to provide electron-pion separation as well as charged-particle tracking. Within this work, thin and symmetric Multi-Wire Proportional Chambers (MWPCs) without additional drift region were proposed. the proposed prototypes feature a foil-based entrance window to minimize the material budget and to reduce the absorption probability of the generated TR photon. Based on the conceptual design of thin and symmetric MWPCs without drift region, multiple prototypes were constructed and their performance presented within this thesis. With the constructed prototypes of generations II and III the geometries of the wire and cathode planes were determined to be 4+4 mm and 5+5 mm. Based on the results of a performed test beam campaign in 2011 with this prototypes new prototypes of generation IV were manufactured and tested in a subsequent test beam campaign in 2012. Prototypes of different radiators were developed together with the MWPC prototypes. Along with regular foil radiators, foam-based radiator types made of polyethylene foam were utilized. Also radiators constructed in a sandwich design, which used different fiber materials confined with solid foam sheets, were used. For the prototypes without drift region, simulations of the electrostatic and mechanical properties were performed. The GARFIELD software package was used to simulate the electric field and to determine the resulting drift lines of the generated electrons. The mean gas amplification depending on the utilized gas and the applied anode voltage was simulated and the gas-gain homogeneity was verified. Since the thin foil-based entrance window experiences a deformation due to pressure differences inside and outside the MWPC, the variation on the gas gain depending on the deformation was simulated. The mechanical properties focusing on the stability of the entrance window was determined with a finiteelement

  14. Visible and dark matter from a first-order phase transition in a baryon-symmetric universe

    International Nuclear Information System (INIS)

    Petraki, Kalliopi; Volkas, Raymond R.; Trodden, Mark

    2012-01-01

    The similar cosmological abundances observed for visible and dark matter suggest a common origin for both. By viewing the dark matter density as a dark-sector asymmetry, mirroring the situation in the visible sector, we show that the visible and dark matter asymmetries may have arisen simultaneously through a first-order phase transition in the early universe. The dark asymmetry can then be equal and opposite to the usual visible matter asymmetry, leading to a universe that is symmetric with respect to a generalised baryon number. We present both a general structure, and a precisely defined example of a viable model of this type. In that example, the dark matter is ''atomic'' as well as asymmetric, and various cosmological and astrophysical constraints are derived. Testable consequences for colliders include a Z' boson that couples through the B−L charge to the visible sector, but also decays invisibly to dark sector particles. The additional scalar particles in the theory can mix with the standard Higgs boson and provide other striking signatures

  15. Exploring high-density baryonic matter: Maximum freeze-out density

    Energy Technology Data Exchange (ETDEWEB)

    Randrup, Joergen [Lawrence Berkeley National Laboratory, Nuclear Science Division, Berkeley, CA (United States); Cleymans, Jean [University of Cape Town, UCT-CERN Research Centre and Department of Physics, Rondebosch (South Africa)

    2016-08-15

    The hadronic freeze-out line is calculated in terms of the net baryon density and the energy density instead of the usual T and μ{sub B}. This analysis makes it apparent that the freeze-out density exhibits a maximum as the collision energy is varied. This maximum freeze-out density has μ{sub B} = 400 - 500 MeV, which is above the critical value, and it is reached for a fixed-target bombarding energy of 20-30 GeV/N well within the parameters of the proposed NICA collider facility. (orig.)

  16. Cosmological leverage from the matter power spectrum in the presence of baryon and nonlinear effects

    International Nuclear Information System (INIS)

    Bielefeld, Jannis; Huterer, Dragan; Linder, Eric V.

    2015-01-01

    We investigate how the use of higher wavenumbers (smaller scales) in the galaxy clustering power spectrum influences cosmological constraints. We take into account uncertainties from nonlinear density fluctuations, (scale dependent) galaxy bias, and baryonic effects. Allowing for substantially model independent uncertainties through separate fit parameters in each wavenumber bin that also allow for the redshift evolution, we quantify strong gains in dark energy and neutrino mass leverage with increasing maximum wavenumber, despite marginalizing over numerous (up to 125) extra fit parameters. The leverage is due to not only an increased number of modes but, more significantly, breaking of degeneracies beyond the linear regime

  17. Molecular dynamics simulation for the baryon-quark phase transition at finite baryon density

    International Nuclear Information System (INIS)

    Akimura, Y.; Maruyama, T.; Chiba, S.; Yoshinaga, N.

    2005-01-01

    We study the baryon-quark phase transition in the molecular dynamics (MD) of the quark degrees of freedom at finite baryon density. The baryon state at low baryon density, and the deconfined quark state at high baryon density are reproduced. We investigate the equations of state of matters with different u-d-s compositions. It is found that the baryon-quark transition is sensitive to the quark width. (orig.)

  18. White matter biomarkers from diffusion MRI

    Science.gov (United States)

    Nørhøj Jespersen, Sune

    2018-06-01

    As part of an issue celebrating 2 decades of Joseph Ackerman editing the Journal of Magnetic Resonance, this paper reviews recent progress in one of the many areas in which Ackerman and his lab has made significant contributions: NMR measurement of diffusion in biological media, specifically in brain tissue. NMR diffusion signals display exquisite sensitivity to tissue microstructure, and have the potential to offer quantitative and specific information on the cellular scale orders of magnitude below nominal image resolution when combined with biophysical modeling. Here, I offer a personal perspective on some recent advances in diffusion imaging, from diffusion kurtosis imaging to microstructural modeling, and the connection between the two. A new result on the estimation accuracy of axial and radial kurtosis with axially symmetric DKI is presented. I moreover touch upon recently suggested generalized diffusion sequences, promising to offer independent microstructural information. We discuss the need and some methods for validation, and end with an outlook on some promising future directions.

  19. Charge diffusion and the butterfly effect in striped holographic matter

    Energy Technology Data Exchange (ETDEWEB)

    Lucas, Andrew [Department of Physics, Harvard University,Cambridge, MA 02138 (United States); Department of Physics, Stanford University,Stanford, CA 94305 (United States); Steinberg, Julia [Department of Physics, Harvard University,Cambridge, MA 02138 (United States)

    2016-10-26

    Recently, it has been proposed that the butterfly velocity — a speed at which quantum information propagates — may provide a fundamental bound on diffusion constants in dirty incoherent metals. We analytically compute the charge diffusion constant and the butterfly velocity in charge-neutral holographic matter with long wavelength “hydrodynamic' disorder in a single spatial direction. In this limit, we find that the butterfly velocity does not set a sharp lower bound for the charge diffusion constant.

  20. Charge diffusion and the butterfly effect in striped holographic matter

    International Nuclear Information System (INIS)

    Lucas, Andrew; Steinberg, Julia

    2016-01-01

    Recently, it has been proposed that the butterfly velocity — a speed at which quantum information propagates — may provide a fundamental bound on diffusion constants in dirty incoherent metals. We analytically compute the charge diffusion constant and the butterfly velocity in charge-neutral holographic matter with long wavelength “hydrodynamic' disorder in a single spatial direction. In this limit, we find that the butterfly velocity does not set a sharp lower bound for the charge diffusion constant.

  1. Single-particle potential of the Λ hyperon in nuclear matter with chiral effective field theory NLO interactions including effects of Y N N three-baryon interactions

    Science.gov (United States)

    Kohno, M.

    2018-03-01

    Adopting hyperon-nucleon and hyperon-nucleon-nucleon interactions parametrized in chiral effective field theory, single-particle potentials of the Λ and Σ hyperons are evaluated in symmetric nuclear matter and in pure neutron matter within the framework of lowest-order Bruckner theory. The chiral NLO interaction bears strong Λ N -Σ N coupling. Although the Λ potential is repulsive if the coupling is switched off, the Λ N -Σ N correlation brings about the attraction consistent with empirical data. The Σ potential is repulsive, which is also consistent with empirical information. The interesting result is that the Λ potential becomes shallower beyond normal density. This provides the possibility of solving the hyperon puzzle without introducing ad hoc assumptions. The effects of the Λ N N -Λ N N and Λ N N -Σ N N three-baryon forces are considered. These three-baryon forces are first reduced to normal-ordered effective two-baryon interactions in nuclear matter and then incorporated in the G -matrix equation. The repulsion from the Λ N N -Λ N N interaction is of the order of 5 MeV at normal density and becomes larger with increasing density. The effects of the Λ N N -Σ N N coupling compensate the repulsion at normal density. The net effect of the three-baryon interactions on the Λ single-particle potential is repulsive at higher densities.

  2. White matter biomarkers from diffusion MRI

    DEFF Research Database (Denmark)

    Jespersen, Sune

    2018-01-01

    Abstract As part of an issue celebrating 2 decades of Joseph Ackerman editing the Journal of Magnetic Resonance, this paper reviews recent progress in one of the many areas in which Ackerman and his lab has made significant contributions: NMR measurement of diffusion in biological media, specific...

  3. Strange Baryon Physics in Full Lattice QCD

    International Nuclear Information System (INIS)

    Huey-Wen Lin

    2007-01-01

    Strange baryon spectra and form factors are key probes to study excited nuclear matter. The use of lattice QCD allows us to test the strength of the Standard Model by calculating strange baryon quantities from first principles

  4. Horizontal branch stars as a probe of non baryonic dark matter

    International Nuclear Information System (INIS)

    Salati, P.; Bouquet, A.; Raffelt, G.; Silk, J.; Grenoble-1 Univ., 74 - Annecy; California Univ., Berkeley, CA

    1989-01-01

    The solar neutrino problem can be interpreted as a signature for the existence and properties of certain dark matter candidate particles (''cosmions''). We investigate the breaking of convection by neutrino-like cosmions in horizontal branch (HB) stars. These particles may affect globular clusters in the inner galaxy or in dwarf spheroidals where the dark matter density is larger than in the solar neighborhood, leading to an observable reduction of the HB lifetime. 10 refs., 1 fig

  5. Possible interaction between baryons and dark-matter particles revealed by the first stars

    Science.gov (United States)

    Barkana, Rennan

    2018-03-01

    The cosmic radio-frequency spectrum is expected to show a strong absorption signal corresponding to the 21-centimetre-wavelength transition of atomic hydrogen around redshift 20, which arises from Lyman-α radiation from some of the earliest stars. By observing this 21-centimetre signal—either its sky-averaged spectrum or maps of its fluctuations, obtained using radio interferometers—we can obtain information about cosmic dawn, the era when the first astrophysical sources of light were formed. The recent detection of the global 21-centimetre spectrum reveals a stronger absorption than the maximum predicted by existing models, at a confidence level of 3.8 standard deviations. Here we report that this absorption can be explained by the combination of radiation from the first stars and excess cooling of the cosmic gas induced by its interaction with dark matter. Our analysis indicates that the spatial fluctuations of the 21-centimetre signal at cosmic dawn could be an order of magnitude larger than previously expected and that the dark-matter particle is no heavier than several proton masses, well below the commonly predicted mass of weakly interacting massive particles. Our analysis also confirms that dark matter is highly non-relativistic and at least moderately cold, and primordial velocities predicted by models of warm dark matter are potentially detectable. These results indicate that 21-centimetre cosmology can be used as a dark-matter probe.

  6. Possible interaction between baryons and dark-matter particles revealed by the first stars.

    Science.gov (United States)

    Barkana, Rennan

    2018-02-28

    The cosmic radio-frequency spectrum is expected to show a strong absorption signal corresponding to the 21-centimetre-wavelength transition of atomic hydrogen around redshift 20, which arises from Lyman-α radiation from some of the earliest stars. By observing this 21-centimetre signal-either its sky-averaged spectrum or maps of its fluctuations, obtained using radio interferometers-we can obtain information about cosmic dawn, the era when the first astrophysical sources of light were formed. The recent detection of the global 21-centimetre spectrum reveals a stronger absorption than the maximum predicted by existing models, at a confidence level of 3.8 standard deviations. Here we report that this absorption can be explained by the combination of radiation from the first stars and excess cooling of the cosmic gas induced by its interaction with dark matter. Our analysis indicates that the spatial fluctuations of the 21-centimetre signal at cosmic dawn could be an order of magnitude larger than previously expected and that the dark-matter particle is no heavier than several proton masses, well below the commonly predicted mass of weakly interacting massive particles. Our analysis also confirms that dark matter is highly non-relativistic and at least moderately cold, and primordial velocities predicted by models of warm dark matter are potentially detectable. These results indicate that 21-centimetre cosmology can be used as a dark-matter probe.

  7. Shock discontinuities around the confinement-deconfinement transition in baryon-rich dense matter

    International Nuclear Information System (INIS)

    Rischke, D.H.; Waldhauser, B.M.; Stoecker, H.; Greiner, W.; Friman, B.L.

    1989-05-01

    We investigate shock discontinuities that involve a conversion of hadronic matter into quark-gluon matter and vice versa. Such discontinuities may develop when nuclear matter is compressed to energy densities beyond the deconfinement transition and in the hadronization of an expanding quark-gluon plasma. In these investigations we study the influence of various phenomenological equations of state. Consequences for entropy production in heavy-ion collisions are discussed and estimates of inclusive particle ratios at freeze-out are given. We find that antiparticle-to-particle ratios may be enhanced by an order of magnitude if a quark-gluon plasma is created during the collision compared to a purely hadronic collision scenario. (orig.)

  8. Preamplifier-shaper prototype for the Fast Transition Detector of the Compressed Baryonic Matter (CBM) experiment at FAIR

    CERN Document Server

    Soltveit, Hans Kristian

    2007-01-01

    In this work a preamplifier-shaper prototype for the Fast Transition Detector of the Compressed BaryonicMatter (CBM) experiment at FAIR fabricated using a 0.35 μm CMOS technology will be presented. The ASIC integrates 16 identical Charge Sensitive Amplifiers (CSA) followed by a Pole-Zero network, two bridged-T filters, Common-Mode FeedBack (CMFB) network and two non-inverting level shifting stages. The circuit is optimized for a detector capacitance Cd of (5-10)pF. Measurement results confirm the noise of 330 e− + 12 e−/pF obtained in simulations for a pulse with a Full Width Half Maximum (FWHM) of 71 ns. The circuit recovers to the baseline within 200 ns. The conversion gain is 12.64 mV/fC. An integral nonlinearity of 0.7% is also achieved. The maximum output swing is 2 V. The power consumption is 16 mW/channel where the main contributors are the input transistor and the level shifting stage with 5.3 mW and 6.6 mW, respectively. The total area of the chip is 12 mm2. Although the circuit was designed for...

  9. Dark matter gravitinos and baryons via Q-ball decay in the gauge-mediated MSSM

    Energy Technology Data Exchange (ETDEWEB)

    Doddato, Francesca; McDonald, John, E-mail: f.doddato@lancaster.ac.uk, E-mail: j.mcdonald@lancaster.ac.uk [Lancaster-Manchester-Sheffield Consortium for Fundamental Physics, Cosmology and Astroparticle Physics Group, Dept. of Physics, University of Lancaster, Lancaster LA1 4YB (United Kingdom)

    2013-07-01

    We show that late Q-ball decay in the MSSM with gauge-mediated SUSY breaking can provide a natural source of non-thermal NLSPs which subsequently decay to gravitino dark matter without violating nucleosynthesis constraints. To show this, we perform a global analysis of Q-ball formation and decay in Affleck-Dine baryogenesis for a d = 6 (u{sup c}d{sup c}d{sup c}){sup 2} flat direction of the gauge-mediated MSSM. A general phenomenological potential for the flat-direction is studied and the Q-ball decay properties are obtained as a function of its parameters. The corresponding gravitino mass necessary to account for dark matter is then determined for the case of stau NLSPs. The decay temperature depends on the charge of the Q-balls, which is determined by the fragmentation of the AD condensate. Different fragmentation scenarios are considered, and the final non-thermal NLSP density from Q-ball decay and NLSP annihilation is determined. Particular care is taken to establish that NLSPs from Q-ball decay become homogeneous and non-relativistic prior to annihilation. The gravitino mass necessary for dark matter is naturally consistent with the theoretical gravitino mass in the gauge-mediation model.

  10. Dark matter gravitinos and baryons via Q-ball decay in the gauge-mediated MSSM

    International Nuclear Information System (INIS)

    Doddato, Francesca; McDonald, John

    2013-01-01

    We show that late Q-ball decay in the MSSM with gauge-mediated SUSY breaking can provide a natural source of non-thermal NLSPs which subsequently decay to gravitino dark matter without violating nucleosynthesis constraints. To show this, we perform a global analysis of Q-ball formation and decay in Affleck-Dine baryogenesis for a d = 6 (u c d c d c ) 2 flat direction of the gauge-mediated MSSM. A general phenomenological potential for the flat-direction is studied and the Q-ball decay properties are obtained as a function of its parameters. The corresponding gravitino mass necessary to account for dark matter is then determined for the case of stau NLSPs. The decay temperature depends on the charge of the Q-balls, which is determined by the fragmentation of the AD condensate. Different fragmentation scenarios are considered, and the final non-thermal NLSP density from Q-ball decay and NLSP annihilation is determined. Particular care is taken to establish that NLSPs from Q-ball decay become homogeneous and non-relativistic prior to annihilation. The gravitino mass necessary for dark matter is naturally consistent with the theoretical gravitino mass in the gauge-mediation model

  11. Heavy baryons

    International Nuclear Information System (INIS)

    Koerner, J.G.

    1994-06-01

    We review the experimental and theoretical status of baryons containing one heavy quark. The charm and bottom baryon states are classified and their mass spectra are listed. The appropriate theoretical framework for the description of heavy baryons is the Heavy Quark Effective Theory, whose general ideas and methods are introduced and illustrated in specific examples. We present simple covariant expressions for the spin wave functions of heavy baryons including p-wave baryons. The covariant spin wave functions are used to determine the Heavy Quark Symmetry structure of flavour-changing current-induced transitions between heavy baryons as well as one-pion and one-photon transitions between heavy baryons of the same flavour. We discuss 1/m Q corrections to the current-induced transitions as well as the structure of heavy to light baryon transitions. Whenever possible we attempt to present numbers to compare with experiment by making use of further model-dependent assumptions as e.g. the constituent picture for light quarks. We highlight recent advances in the theoretical understanding of the inclusive decays of hadrons containing one heavy quark including polarization. For exclusive semileptonic decays we discuss rates, angular decay distributions and polarization effects. We provide an update of the experimental and theoretical status of lifetimes of heavy baryons and of exclusive nonleptonic two body decays of charm baryons. (orig.)

  12. Diffusive instability of a kaon condensate in neutron star matter

    International Nuclear Information System (INIS)

    Kubis, Sebastian

    2004-01-01

    The beta equilibrated dense matter with kaon condensate is analyzed with respect to extended stability conditions, including charge fluctuations. This kind of the diffusive instability appeared to be common property in the kaon condensation case. Results for three different nuclear models are presented

  13. MACHe3: A new generation detector for non-baryonic dark matter direct detection

    International Nuclear Information System (INIS)

    Santos, D.; Mayet, F.; Perrin, G.; Moulin, E.; Bunkov, Yu. M.; Godfrin, H.; Krusius, M.

    2002-01-01

    MACHe3 (MAtrix of Cells of superfluid 3 H e) is a project of a new detector for direct Dark Matter (DM) search, using superfluid 3 He as a sensitive medium. An experiment on a prototype cell has been performed and the st results reported here are encouraging to develop of a multicell prototype. In order to investigate the discovery potential of MACHe3, and its complementarity with other DM detectors, a phenomenological study done with the DarkSUSY code is shown. (authors)

  14. Dense baryon matter with isospin and chiral imbalance in the framework of a NJL4 model at large Nc: Duality between chiral symmetry breaking and charged pion condensation

    Science.gov (United States)

    Khunjua, T. G.; Klimenko, K. G.; Zhokhov, R. N.

    2018-03-01

    In this paper the phase structure of dense quark matter has been investigated at zero temperature in the presence of baryon, isospin and chiral isospin chemical potentials in the framework of massless (3 +1 )-dimensional Nambu-Jona-Lasinio model with two quark flavors. It has been shown that in the large-Nc limit (Nc is the number of colors of quarks) there exists a duality correspondence between the chiral symmetry breaking phase and the charged pion condensation one. The key conclusion of our studies is the fact that chiral isospin chemical potential generates charged pion condensation in dense quark matter with isotopic asymmetry.

  15. Are baryonic galactic halos possible

    International Nuclear Information System (INIS)

    Olive, K.A.; Hegyi, D.J.

    1986-01-01

    There is little doubt from the rotation curves of spiral galaxies that galactic halos must contain large amounts of dark matter. In this contribution, the authors review arguments which indicate that it is very unlikely that galactic halos contain substantial amounts of baryonic matter. While the authors would like to be able to present a single argument which would rule out baryonic matter, at the present time they are only able to present a collection of arguments each of which argues against one form of baryonic matter. These include: 1) snowballs; 2) gas; 3) low mass stars and Jupiters; 4) high mass stars; and 5) high metalicity objects such as rooks or dust. Black holes, which do not have a well defined baryon number, are also a possible candidate for halo matter. They briefly discuss black holes

  16. Baryon Resonances

    International Nuclear Information System (INIS)

    Oset, E.; Sarkar, S.; Sun Baoxi; Vicente Vacas, M.J.; Ramos, A.; Gonzalez, P.; Vijande, J.; Martinez Torres, A.; Khemchandani, K.

    2010-01-01

    In this talk I show recent results on how many excited baryon resonances appear as systems of one meson and one baryon, or two mesons and one baryon, with the mesons being either pseudoscalar or vectors. Connection with experiment is made including a discussion on old predictions and recent results for the photoproduction of the Λ(1405) resonance, as well as the prediction of one 1/2 + baryon state around 1920 MeV which might have been seen in the γp→K + Λ reaction.

  17. Performances of diffusion kurtosis imaging and diffusion tensor imaging in detecting white matter abnormality in schizophrenia

    Directory of Open Access Journals (Sweden)

    Jiajia Zhu

    2015-01-01

    Full Text Available Diffusion kurtosis imaging (DKI is an extension of diffusion tensor imaging (DTI, exhibiting improved sensitivity and specificity in detecting developmental and pathological changes in neural tissues. However, little attention was paid to the performances of DKI and DTI in detecting white matter abnormality in schizophrenia. In this study, DKI and DTI were performed in 94 schizophrenia patients and 91 sex- and age-matched healthy controls. White matter integrity was assessed by fractional anisotropy (FA, mean diffusivity (MD, axial diffusivity (AD, radial diffusivity (RD, mean kurtosis (MK, axial kurtosis (AK and radial kurtosis (RK of DKI and FA, MD, AD and RD of DTI. Group differences in these parameters were compared using tract-based spatial statistics (TBSS (P  AK (20% > RK (3% and RD (37% > FA (24% > MD (21% for DKI, and RD (43% > FA (30% > MD (21% for DTI. DKI-derived diffusion parameters (RD, FA and MD were sensitive to detect abnormality in white matter regions (the corpus callosum and anterior limb of internal capsule with coherent fiber arrangement; however, the kurtosis parameters (MK and AK were sensitive to reveal abnormality in white matter regions (the juxtacortical white matter and corona radiata with complex fiber arrangement. In schizophrenia, the decreased AK suggests axonal damage; however, the increased RD indicates myelin impairment. These findings suggest that diffusion and kurtosis parameters could provide complementary information and they should be jointly used to reveal pathological changes in schizophrenia.

  18. Effect of organic matter on 125I diffusion in bentonite

    International Nuclear Information System (INIS)

    Tao Wu; Qing Zheng

    2015-01-01

    Through-diffusion method was conducted to investigate the diffusion behavior of 125 I in bentonite in present of organic matter, such as polyaminopolycarboxylate EDTA, oxalic acid, hydrazine and humic acid HA. The effective diffusion coefficient D e value and rock capacity factor α were (2.32.6) × 10 -11 m 2 /s and 0.040-0.052, respectively. The small difference showed that iodine was preferentially associated with silicoaluminate mineral as an inorganic form. In present of HA, the D a value of 125 I was almost two orders of magnitude higher than that of HA and humic substances HS. The D e and α derived from the experiments were used to simulate its diffusion in the designed bentonite obstacle of high-level radioactive waste repository and the results showed that 125 I can be transported from 30 to 50 cm thickness of bentonite to the far-field of repository in several years. (author)

  19. A search for non-baryonic dark matter using an ionisation bolometer in the edelweiss experiment

    International Nuclear Information System (INIS)

    Di Stefano, Ph.

    1998-01-01

    The EDELWEISS experiment is an underground direct-detection search for hypothetical supersymmetric WIMPs that might solve the problem of dark matter. We have employed a cryogenic 70 g germanium ionisation bolometer, in which a WIMP would scatter elastically off a nucleus, creating both a heat and an ionisation signal. To offset the various electronic noises present in our necessarily small signals, we have s applied an optimal filtering technique in the frequency domain. This allows us to reach resolutions of 1.2 keV FWHM at 122 keV on north channels. It also provides good separation right down to low energies between the expected signal of nuclear recoils, and the photonic background of electron recoils which ionize more for a given energy. Calibration data show that we are able to reject 99.7 % of this background, while keeping 95% of the signal. However, our 1.17 kg.days of data searching for WIMPs show a third population encroaching on the expected signal. This is probably due to low energy photons or electrons interacting in the outer layers of the crystal, where charges are incompletely collected. Nevertheless, by trading off half of the conserved signal, we still manage to reject 98.5 % of the background. Thus the raw rate of 40 evts/d/kg/keV yields a conservative 90 % upper limit on the signal of 0.6 evts/d/kg/keV. This represents nearly a three orders of magnitude improvement for EDELWEISS, and puts the predicted supersymmetric phase space within two orders of magnitude. (author)

  20. Charming baryons

    International Nuclear Information System (INIS)

    Garcia-Recio, C.; Salcedo, L.L.; Gamermann, D.; Nieves, J.; Romanets, O.; Tolos, L.

    2014-01-01

    We study odd-parity baryonic resonances with one heavy and three light flavors, dynamically generated by meson-baryon interactions. Special attention is paid to Heavy Quark Spin Symmetry (HQSS), hence pseudoscalar and vector mesons and baryons with J π = 1/2 + and 3/2 + are considered as constituent hadrons. For the hidden-charm sector (N c = N c ¯ = 1), the meson-baryon Lagrangian with Heavy Flavor Symmetry is constructed by a minimal extension of the SU(3) Weinberg-Tomozawa (WT) Lagrangian to fulfill HQSS, such that not new parameters are needed. This interaction can be presented in different formal ways: as a Field Lagrangian, as Hadron creation-annihilation operators, as SU(6)×HQSS group projectors and as multichannel matrices. The multichannel Bethe-Salpeter equation is solved for odd-parity light baryons, hidden-charm N and Δ and Beauty Baryons (Λ b ). Results of calculations with this model are shown in comparison with other models and experimental values for baryonic resonances. (author)

  1. The impact of ΛCDM substructure and baryon-dark matter transition on the image positions of quad galaxy lenses

    Science.gov (United States)

    Gomer, Matthew R.; Williams, Liliya L. R.

    2018-04-01

    The positions of multiple images in galaxy lenses are related to the galaxy mass distribution. Smooth elliptical mass profiles were previously shown to be inadequate in reproducing the quad population. In this paper, we explore the deviations from such smooth elliptical mass distributions. Unlike most other work, we use a model-free approach based on the relative polar image angles of quads, and their position in 3D space with respect to the fundamental surface of quads (FSQ). The FSQ is defined by quads produced by elliptical lenses. We have generated thousands of quads from synthetic populations of lenses with substructure consistent with Lambda cold dark matter (ΛCDM) simulations, and found that such perturbations are not sufficient to match the observed distribution of quads relative to the FSQ. The result is unchanged even when subhalo masses are increased by a factor of 10, and the most optimistic lensing selection bias is applied. We then produce quads from galaxies created using two components, representing baryons and dark matter. The transition from the mass being dominated by baryons in inner radii to being dominated by dark matter in outer radii can carry with it asymmetries, which would affect relative image angles. We run preliminary experiments using lenses with two elliptical mass components with non-identical axial ratios and position angles, perturbations from ellipticity in the form of non-zero Fourier coefficients a4 and a6, and artificially offset ellipse centres as a proxy for asymmetry at image radii. We show that combination of these effects is a promising way of accounting for quad population properties. We conclude that the quad population provides a unique and sensitive tool for constraining detailed mass distribution in the centres of galaxies.

  2. Baryon structure

    International Nuclear Information System (INIS)

    Morsch, H.P.; Forschungszentrum Juelich GmbH

    1993-01-01

    A brief review on the theoretical and experimental situation of baryon spectroscopy is first given. Then, the radial structure of baryons, related to the ground state form factors and the baryonic compressibility, is discussed. An experiment has been performed at Saturne laboratory (France) in which for the first time a compression of the nucleon is observed, exciting the P 11 (1440 MeV) resonance (Roper resonance) by α-particles. The analysis of the data indicates that this excitation covers a large fraction of the available monopole strength in the nucleon. The derived compressibility is discussed as well as the consequence for other fields, as nuclear medium effects on baryon properties, high density phenomena in nuclear collisions as well as colour transparency. In the last point the spin-flip structure of the P 11 (1440 MeV) resonance is discussed. The possibility to determine isoscalar spin-flip strength by polarized deuteron scattering is contrasted with first preliminary results from photon-induced reactions studied at Mainz which indicate a non-negligible M1 excitation of the Roper resonance. (author) 10 figs., 31 refs

  3. Whole brain white matter changes revealed by multiple diffusion metrics in multiple sclerosis: A TBSS study

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yaou, E-mail: asiaeurope80@gmail.com [Department of Radiology, Xuanwu Hospital, Capital Medical University, Beijing 100053 (China); Duan, Yunyun, E-mail: xiaoyun81.love@163.com [Department of Radiology, Xuanwu Hospital, Capital Medical University, Beijing 100053 (China); He, Yong, E-mail: yong.h.he@gmail.com [State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing 100875 (China); Yu, Chunshui, E-mail: csyuster@gmail.com [Department of Radiology, Xuanwu Hospital, Capital Medical University, Beijing 100053 (China); Wang, Jun, E-mail: jun_wang@bnu.edu.cn [State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing 100875 (China); Huang, Jing, E-mail: sainthj@126.com [Department of Radiology, Xuanwu Hospital, Capital Medical University, Beijing 100053 (China); Ye, Jing, E-mail: jingye.2007@yahoo.com.cn [Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing 100053 (China); Parizel, Paul M., E-mail: paul.parizel@ua.ac.be [Department of Radiology, Antwerp University Hospital and University of Antwerp, Wilrijkstraat 10, 2650 Edegem, 8 Belgium (Belgium); Li, Kuncheng, E-mail: kunchengli55@gmail.com [Department of Radiology, Xuanwu Hospital, Capital Medical University, Beijing 100053 (China); Shu, Ni, E-mail: nshu55@gmail.com [State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing 100875 (China)

    2012-10-15

    Objective: To investigate whole brain white matter changes in multiple sclerosis (MS) by multiple diffusion indices, we examined patients with diffusion tensor imaging and utilized tract-based spatial statistics (TBSS) method to analyze the data. Methods: Forty-one relapsing-remitting multiple sclerosis (RRMS) patients and 41 age- and gender-matched normal controls were included in this study. Diffusion weighted images were acquired by employing a single-shot echo planar imaging sequence on a 1.5 T MR scanner. Voxel-wise analyses of multiple diffusion metrics, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD) were performed with TBSS. Results: The MS patients had significantly decreased FA (9.11%), increased MD (8.26%), AD (3.48%) and RD (13.17%) in their white matter skeletons compared with the controls. Through TBSS analyses, we found abnormal diffusion changes in widespread white matter regions in MS patients. Specifically, decreased FA, increased MD and increased RD were involved in whole-brain white matter, while several regions exhibited increased AD. Furthermore, white matter regions with significant correlations between the diffusion metrics and the clinical variables (the EDSS scores, disease durations and white matter lesion loads) in MS patients were identified. Conclusion: Widespread white matter abnormalities were observed in MS patients revealed by multiple diffusion metrics. The diffusion changes and correlations with clinical variables were mainly attributed to increased RD, implying the predominant role of RD in reflecting the subtle pathological changes in MS.

  4. Whole brain white matter changes revealed by multiple diffusion metrics in multiple sclerosis: A TBSS study

    International Nuclear Information System (INIS)

    Liu, Yaou; Duan, Yunyun; He, Yong; Yu, Chunshui; Wang, Jun; Huang, Jing; Ye, Jing; Parizel, Paul M.; Li, Kuncheng; Shu, Ni

    2012-01-01

    Objective: To investigate whole brain white matter changes in multiple sclerosis (MS) by multiple diffusion indices, we examined patients with diffusion tensor imaging and utilized tract-based spatial statistics (TBSS) method to analyze the data. Methods: Forty-one relapsing-remitting multiple sclerosis (RRMS) patients and 41 age- and gender-matched normal controls were included in this study. Diffusion weighted images were acquired by employing a single-shot echo planar imaging sequence on a 1.5 T MR scanner. Voxel-wise analyses of multiple diffusion metrics, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD) were performed with TBSS. Results: The MS patients had significantly decreased FA (9.11%), increased MD (8.26%), AD (3.48%) and RD (13.17%) in their white matter skeletons compared with the controls. Through TBSS analyses, we found abnormal diffusion changes in widespread white matter regions in MS patients. Specifically, decreased FA, increased MD and increased RD were involved in whole-brain white matter, while several regions exhibited increased AD. Furthermore, white matter regions with significant correlations between the diffusion metrics and the clinical variables (the EDSS scores, disease durations and white matter lesion loads) in MS patients were identified. Conclusion: Widespread white matter abnormalities were observed in MS patients revealed by multiple diffusion metrics. The diffusion changes and correlations with clinical variables were mainly attributed to increased RD, implying the predominant role of RD in reflecting the subtle pathological changes in MS

  5. Revealing dark matter substructure with anisotropies in the diffuse gamma-ray background

    OpenAIRE

    Siegal-Gaskins, Jennifer M.

    2008-01-01

    The majority of gamma-ray emission from Galactic dark matter annihilation is likely to be detected as a contribution to the diffuse gamma-ray background. I show that dark matter substructure in the halo of the Galaxy induces characteristic anisotropies in the diffuse background that could be used to determine the small-scale dark matter distribution. I calculate the angular power spectrum of the emission from dark matter substructure for several models of the subhalo population, and show that...

  6. Universal properties of relaxation and diffusion in condensed matter

    International Nuclear Information System (INIS)

    Ngai K L

    2017-01-01

    By and large the research communities today are not fully aware of the remarkable universality in the dynamic properties of many-body relaxation/diffusion processes manifested in experiments and simulations on condensed matter with diverse chemical compositions and physical structures. I shall demonstrate the universality first from the dynamic processes in glass-forming systems. This is reinforced by strikingly similar properties of different processes in contrasting interacting systems all having nothing to do with glass transition. The examples given here include glass-forming systems of diverse chemical compositions and physical structures, conductivity relaxation of ionic conductors (liquid, glassy, and crystalline), translation and orientation ordered phase of rigid molecule, and polymer chain dynamics. Universality is also found in the change of dynamics when dimension is reduced to nanometer size in widely different systems. The remarkable universality indicates that many-body relaxation/diffusion is governed by fundamental physics to be unveiled. One candidate is classical chaos on which the coupling model is based, Universal properties predicted by this model are in accord with diverse experiments and simulations. (paper)

  7. Galactic diffusion and the antiproton signal of supersymmetric dark matter

    CERN Document Server

    Chardonnet, P; Salati, Pierre; Taillet, R

    1996-01-01

    The leaky box model is now ruled out by measurements of a cosmic ray gradient throughout the galactic disk. It needs to be replaced by a more refined treatment which takes into account the diffusion of cosmic rays in the magnetic fields of the Galaxy. We have estimated the flux of antiprotons on the Earth in the framework of a two-zone diffusion model. Those species are created by the spallation reactions of high-energy nuclei with the interstellar gas. Another potential source of antiprotons is the annihilation of supersymmetric particles in the dark halo that surrounds our Galaxy. In this letter, we investigate both processes. Special emphasis is given to the antiproton signature of supersymmetric dark matter. The corresponding signal exceeds the conventional spallation flux below 300 MeV, a domain that will be thoroughly explored by the Antimatter Spectrometer experiment. The propagation of the antiprotons produced in the remote regions of the halo back to the Earth plays a crucial role. Depending on the e...

  8. Excited baryons

    International Nuclear Information System (INIS)

    Mukhopadhyay, N.C.

    1986-01-01

    The status of the theory of the low-energy approach to hadron structure is reviewed briefly by surveying a few relevant models. A few examples of tests needed to sort out the predictions of different models pertaining to the quark-gluon structure of hadrons are discussed, and given the resulting physics objectives, a few experimental options for excited baryon research at CFBAF are suggested

  9. Excited baryons

    Energy Technology Data Exchange (ETDEWEB)

    Mukhopadhyay, N.C.

    1986-01-01

    The status of the theory of the low-energy approach to hadron structure is reviewed briefly by surveying a few relevant models. A few examples of tests needed to sort out the predictions of different models pertaining to the quark-gluon structure of hadrons are discussed, and given the resulting physics objectives, a few experimental options for excited baryon research at CFBAF are suggested. (LEW)

  10. Exploring the multiple-hit hypothesis of preterm white matter damage using diffusion MRI

    Directory of Open Access Journals (Sweden)

    Madeleine L. Barnett

    2018-01-01

    Conclusion: This study suggests multiple perinatal risk factors have an independent association with diffuse white matter injury at term equivalent age and exposure to multiple perinatal risk factors exacerbates dMRI defined, clinically significant white matter injury. Our findings support the multiple hit hypothesis for preterm white matter injury.

  11. Some Like it Hot: Linking Diffuse X-Ray Luminosity, Baryonic Mass, and Star Formation Rate in Compact Groups of Galaxies

    Science.gov (United States)

    Desjardins, Tyler D.; Gallagher, Sarah C.; Hornschemeier, Ann E.; Mulchaey, John S.; Walker, Lisa May; Brandt, Willian N.; Charlton, Jane C.; Johnson, Kelsey E.; Tzanavaris, Panayiotis

    2014-01-01

    We present an analysis of the diffuse X-ray emission in 19 compact groups (CGs) of galaxies observed with Chandra. The hottest, most X-ray luminous CGs agree well with the galaxy cluster X-ray scaling relations in L(x-T) and (L(x-sigma), even in CGs where the hot gas is associated with only the brightest galaxy. Using Spitzer photometry, we compute stellar masses and classify Hickson CGs 19, 22, 40, and 42, and RSCGs 32, 44, and 86 as fossil groups using a new definition for fossil systems that includes a broader range of masses. We find that CGs with total stellar and Hi masses are great than or equal to 10(sup (11.3) solar mass are often X-ray luminous, while lower-mass CGs only sometimes exhibit faint, localized X-ray emission. Additionally, we compare the diffuse X-ray luminosity against both the total UV and 24 micron star formation rates of each CG and optical colors of the most massive galaxy in each of the CGs. The most X-ray luminous CGs have the lowest star formation rates, likely because there is no cold gas available for star formation, either because the majority of the baryons in these CGs are in stars or the X-ray halo, or due togas stripping from the galaxies in CGs with hot halos. Finally, the optical colors that trace recent star formation histories of the most massive group galaxies do not correlate with the X-ray luminosities of the CGs, indicating that perhaps the current state of the X-ray halos is independent of the recent history of stellar mass assembly in the most massive galaxies.

  12. Diffusion-tensor MR imaging of gray and white matter development during normal human brain maturation.

    Science.gov (United States)

    Mukherjee, Pratik; Miller, Jeffrey H; Shimony, Joshua S; Philip, Joseph V; Nehra, Deepika; Snyder, Abraham Z; Conturo, Thomas E; Neil, Jeffrey J; McKinstry, Robert C

    2002-10-01

    Conventional MR imaging findings of human brain development are thought to result from decreasing water content, increasing macromolecular concentration, and myelination. We use diffusion-tensor MR imaging to test theoretical models that incorporate hypotheses regarding how these maturational processes influence water diffusion in developing gray and white matter. Experimental data were derived from diffusion-tensor imaging of 167 participants, ages 31 gestational weeks to 11 postnatal years. An isotropic diffusion model was applied to the gray matter of the basal ganglia and thalamus. A model that assumes changes in the magnitude of diffusion while maintaining cylindrically symmetric anisotropy was applied to the white matter of the corpus callosum and internal capsule. Deviations of the diffusion tensor from the ideal model predictions, due to measurement noise, were estimated by using Monte Carlo simulations. Developing gray matter of the basal ganglia and developing white matter of the internal capsule and corpus callosum largely conformed to theory, with only small departures from model predictions in older children. However, data from the thalamus substantially diverged from predicted values, with progressively larger deviations from the model with increasing participant age. Changes in water diffusion during maturation of central gray and white matter structures can largely be explained by theoretical models incorporating simple assumptions regarding the influence of brain water content and myelination, although deviations from theory increase as the brain matures. Diffusion-tensor MR imaging is a powerful method for studying the process of brain development, with both scientific and clinical applications.

  13. Charmed baryonic resonances in medium

    Directory of Open Access Journals (Sweden)

    Tolos Laura

    2015-01-01

    Full Text Available We discuss the behavior of dynamically-generated charmed baryonic resonances in matter within a unitarized coupled-channel model consistent with heavy-quark spin symmetry. We analyze the implications for the formation of D-meson bound states in nuclei and the propagation of D mesons in heavy-ion collisions from RHIC to FAIR energies.

  14. Probing white-matter microstructure with higher-order diffusion tensors and susceptibility tensor MRI

    Science.gov (United States)

    Liu, Chunlei; Murphy, Nicole E.; Li, Wei

    2012-01-01

    Diffusion MRI has become an invaluable tool for studying white matter microstructure and brain connectivity. The emergence of quantitative susceptibility mapping and susceptibility tensor imaging (STI) has provided another unique tool for assessing the structure of white matter. In the highly ordered white matter structure, diffusion MRI measures hindered water mobility induced by various tissue and cell membranes, while susceptibility sensitizes to the molecular composition and axonal arrangement. Integrating these two methods may produce new insights into the complex physiology of white matter. In this study, we investigated the relationship between diffusion and magnetic susceptibility in the white matter. Experiments were conducted on phantoms and human brains in vivo. Diffusion properties were quantified with the diffusion tensor model and also with the higher order tensor model based on the cumulant expansion. Frequency shift and susceptibility tensor were measured with quantitative susceptibility mapping and susceptibility tensor imaging. These diffusion and susceptibility quantities were compared and correlated in regions of single fiber bundles and regions of multiple fiber orientations. Relationships were established with similarities and differences identified. It is believed that diffusion MRI and susceptibility MRI provide complementary information of the microstructure of white matter. Together, they allow a more complete assessment of healthy and diseased brains. PMID:23507987

  15. White matter microstructure in transsexuals and controls investigated by diffusion tensor imaging

    NARCIS (Netherlands)

    Kranz, Georg S; Hahn, Andreas; Kaufmann, Ulrike; Küblböck, Martin; Hummer, Allan; Ganger, Sebastian; Seiger, Rene; Winkler, Dietmar; Swaab, Dick F; Windischberger, Christian; Kasper, Siegfried; Lanzenberger, Rupert

    2014-01-01

    Biological causes underpinning the well known gender dimorphisms in human behavior, cognition, and emotion have received increased attention in recent years. The advent of diffusion-weighted magnetic resonance imaging has permitted the investigation of the white matter microstructure in

  16. Homogeneity based segmentation and enhancement of Diffusion Tensor Images : a white matter processing framework

    OpenAIRE

    Rodrigues, P.R.

    2011-01-01

    In diffusion magnetic resonance imaging (DMRI) the Brownian motion of the water molecules, within biological tissue, is measured through a series of images. In diffusion tensor imaging (DTI) this diffusion is represented using tensors. DTI describes, in a non-invasive way, the local anisotropy pattern enabling the reconstruction of the nervous fibers - dubbed tractography. DMRI constitutes a powerful tool to analyse the structure of the white matter within a voxel, but also to investigate the...

  17. Diffusion tensor imaging, white matter lesions, the corpus callosum, and gait in the elderly

    Science.gov (United States)

    Gait impairment is common in the elderly, especially affected by stroke and white matter hyper intensities found in conventional brain magnetic resonance imaging (MRI). Diffusion tensor imaging (DTI) is more sensitive to white matter damage than conventional MRI. The relationship between DTI measure...

  18. Holographic black hole engineering at finite baryon chemical potential

    International Nuclear Information System (INIS)

    Rougemont, Romulo

    2017-01-01

    This is a contribution for the Proceedings of the Conference Hot Quarks 2016, held at South Padre Island, Texas, USA, 12-17 September 2016. I briefly review some thermodynamic and baryon transport results obtained from a bottom-up Einstein-Maxwell-Dilaton holographic model engineered to describe the physics of the quark-gluon plasma at finite temperature and baryon density. The results for the equation of state, baryon susceptibilities, and the curvature of the crossover band are in quantitative agreement with the corresponding lattice QCD results with 2 + 1 flavors and physical quark masses. Baryon diffusion is predicted to be suppressed by increasing the baryon chemical potential. (paper)

  19. Regional diffusion changes of cerebral grey matter during normal aging-A fluid-inversion prepared diffusion imaging study

    International Nuclear Information System (INIS)

    Ni Jianming; Chen Shuang; Liu Jianjun; Huang Gang; Shen Tianzhen; Chen Xingrong

    2010-01-01

    Background and purpose: Although diffusion characteristics of white matter (WM) and its aging effects have been well described in the literature, diffusion characteristics of grey matter (GM), especially the cortical GM, have not been fully evaluated. In the present study, we used the fluid-inversion prepared diffusion imaging (FLIPD) technique to determine if there are age-related water diffusivity changes in GM. Materials and methods: 120 healthy volunteers were recruited for our study. They were divided into three age groups: group one (20-39 years old), group two (40-59 years old) and group three (60 years or older). All patients were evaluated with MRI using FLIPD at 3.0 T. Apparent diffusion coefficient (ADC) values of the frontal GM, cingulate cortex and thalami were determined bilaterally by region-of-interest analysis. Results: Group three had significantly higher ADC values in both thalami and the left frontal GM compared to group two or group one. No ADC value difference was found among the three groups in the right frontal GM and bilateral cingulate cortex. There was a significant positive correlation between individual ADC values and age in both thalami and left frontal GM. For the cingulate cortex and the right frontal GM, ADC values did not correlate significantly with advancing age. Conclusion: Statistically significant age-related diffusion changes were observed in both thalami and the left frontal cortex. The data reported here may serve as a reference for future studies.

  20. Diffusion-weighted magnetic resonance imaging of cerebral white matter development

    International Nuclear Information System (INIS)

    Prayer, Daniela.; Prayer, Lucas

    2003-01-01

    Diffusion-weighted magnetic resonance imaging (DWI) has become a sensitive tool to monitor white matter development. Different applications of diffusion-weighted techniques provide information about premyelinating, myelinating, and postmyelinating states of white matter maturation. Mirroring maturational processes on the cellular level, DWI has to be regarded as a morphological method as well as a functional instrument, giving insight into molecular processes during the formation of axons and myelin sheets and into the steric arrangement of white matter tracts the formation of which is strongly influenced by their function

  1. Diffusion-weighted magnetic resonance imaging of cerebral white matter development

    Energy Technology Data Exchange (ETDEWEB)

    Prayer, Daniela. E-mail: daniela.prayer@univie.ac.at; Prayer, Lucas

    2003-03-01

    Diffusion-weighted magnetic resonance imaging (DWI) has become a sensitive tool to monitor white matter development. Different applications of diffusion-weighted techniques provide information about premyelinating, myelinating, and postmyelinating states of white matter maturation. Mirroring maturational processes on the cellular level, DWI has to be regarded as a morphological method as well as a functional instrument, giving insight into molecular processes during the formation of axons and myelin sheets and into the steric arrangement of white matter tracts the formation of which is strongly influenced by their function.

  2. Diffusion-Weighted MR Imaging of Unusual White Matter Lesion in a Patient with Menkes Disease

    International Nuclear Information System (INIS)

    Lee, Eun Shin; Ryoo, Jae Wook; Choi, Dae Seob; Cho, Jae Min; Kwon, Soo Hyun; Shin, Hee Suk

    2007-01-01

    We report here on the diffusion-weighted imaging of unusual white matter lesions in a case of Menkes disease. On the initial MR imaging, the white matter lesions were localized in the deep periventricular white matter in the absence of diffuse cortical atrophy. The lesion showed diffuse high signal on the diffusion weighted images and diffuse progression and persistent hyperintensity on the follow up imaging. Our case suggests that the white matter lesion may precede diffuse cortical atrophy in a patient with Menkes disease. Menkes disease is an X-linked disorder that's caused by impaired intracellular transport of copper. We describe here the DWI findings of unusual and progressive white matter lesions in a case of Menkes disease. Menkes disease is an X-linked recessive disorder, and it is due to an inborn error of copper metabolism. The cause of Menkes disease has been isolated to a genetic defect in copper-transporting adenosine triphosphatase, and this results in low levels of intracellular copper. It is characterized clinically by failure to thrive, retarded mental and motor development, clonic seizure and peculiarly coarse, sparse and colorless scalp hair. These clinical findings can be explained by a dysfunction of the copper-dependent enzymes

  3. Usefulness of Diffusion Tensor Imaging of White Matter in Alzheimer Disease and Vascular Dementia

    International Nuclear Information System (INIS)

    Sugihara, S.; Kinoshita, T.; Matsusue, E.; Fujii, S.; Ogawa, T.

    2004-01-01

    Purpose: To evaluate the usefulness of diffusion tensor imaging in detecting the water diffusivity caused by neuro pathological change in Alzheimer disease and vascular dementia. Material and Methods: Twenty patients with Alzheimer disease, 20 with vascular dementia, and 10 control subjects were examined. Diffusion tensor imaging applied diffusion gradient encoding in six non-collinear directions. Fractional anisotropy values were compared in the genu and splenium of the corpus callosum, and anterior and posterior white matter among the three groups. Results: In the patients with Alzheimer disease, fractional anisotropy values of the posterior white matter were significantly lower than those of controls. In patients with vascular dementia, fractional anisotropy values of the anterior white matter tended to be lower than those of the posterior white matter (P=0.07). Conclusion: Diffusion tensor imaging reflects the neuro pathological changes in the white matter, and may be useful in the diagnosis of Alzheimer disease and vascular dementia. Keywords: Alzheimer disease, .; diffusion tensor imaging, .; vascular dementia

  4. Study of new germanium bolometers with interleaved concentric electrodes for non-baryonic cold dark matter direct detection in the Edelweiss-II experiment

    International Nuclear Information System (INIS)

    Domange, J.

    2011-09-01

    EDELWEISS is a direct non-baryonic cold dark matter detection experiment in the form of weakly interacting massive particles (also known as WIMPs), which currently constitute the most popular candidates to account for the missing mass in the Universe. To this purpose, EDELWEISS uses germanium bolometers at cryogenic temperature (20 mK approximately) in the Underground Laboratory of Modane (LSM) at the French-Italian border. Since 2008, a new type of detector is operated, equipped with concentric electrodes to optimize the rejection of surface events (coplanar-grid detectors). This thesis work is divided into several research orientations. First, we carried out measurements concerning charge collection in the crystals. The velocity laws of the carriers (electrons and holes) have been determined in germanium at 20 mK in the orientation, and a complete study of charge sharing has been done, including an evaluation of the transport anisotropy and of the straggling of the carriers. These results lead to a better understanding of the inner properties of the EDELWEISS detectors. Then, studies relating to the improvement of the performances were carried out. In particular, we have optimized the space-charge cancellation procedure in the crystals and improved the passive rejection of surface events (β). The fiducial volume of the detectors has been evaluated using two X-ray lines from cosmically activated radionuclides: 68 Ge and 65 Zn. Finally, an exhaustive study of the low energy spectra has been carried out, which makes it possible to develop a systematic analysis method for the search of low-mass WIMPs in EDELWEISS. (author)

  5. When mechanism matters: Bayesian forecasting using models of ecological diffusion

    Science.gov (United States)

    Hefley, Trevor J.; Hooten, Mevin B.; Russell, Robin E.; Walsh, Daniel P.; Powell, James A.

    2017-01-01

    Ecological diffusion is a theory that can be used to understand and forecast spatio-temporal processes such as dispersal, invasion, and the spread of disease. Hierarchical Bayesian modelling provides a framework to make statistical inference and probabilistic forecasts, using mechanistic ecological models. To illustrate, we show how hierarchical Bayesian models of ecological diffusion can be implemented for large data sets that are distributed densely across space and time. The hierarchical Bayesian approach is used to understand and forecast the growth and geographic spread in the prevalence of chronic wasting disease in white-tailed deer (Odocoileus virginianus). We compare statistical inference and forecasts from our hierarchical Bayesian model to phenomenological regression-based methods that are commonly used to analyse spatial occurrence data. The mechanistic statistical model based on ecological diffusion led to important ecological insights, obviated a commonly ignored type of collinearity, and was the most accurate method for forecasting.

  6. Diffuse gamma ray constraints on annihilating or decaying Dark Matter after Fermi

    International Nuclear Information System (INIS)

    Cirelli, Marco; Panci, Paolo; Serpico, Pasquale D.

    2010-01-01

    We consider the diffuse gamma ray data from Fermi first year observations and compare them to the gamma ray fluxes predicted by Dark Matter annihilation or decay (both from prompt emission and from Inverse Compton Scattering), for different observation regions of the sky and a range of Dark Matter masses, annihilation/decay channels and Dark Matter galactic profiles. We find that the data exclude large regions of the Dark Matter parameter space not constrained otherwise and discuss possible directions for future improvements. Also, we further constrain Dark Matter interpretations of the e ± PAMELA/Fermi spectral anomalies, both for the annihilating and the decaying Dark Matter case: under very conservative assumptions, only models producing dominantly μ ± and assuming a cored Dark Matter galactic profile can fit the lepton data with masses around ∼2 TeV.

  7. Baryon Chiral Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Becher,

    2002-08-08

    After contrasting the low energy effective theory for the baryon sector with one for the Goldstone sector, I use the example of pion nucleon scattering to discuss some of the progress and open issues in baryon chiral perturbation theory.

  8. Microstructural changes in ischemic cortical gray matter predicted by a model of diffusion-weighted MRI.

    Science.gov (United States)

    Vestergaard-Poulsen, Peter; Hansen, Brian; Ostergaard, Leif; Jakobsen, Rikke

    2007-09-01

    To understand the diffusion attenuated MR signal from normal and ischemic brain tissue in order to extract structural and physiological information using mathematical modeling, taking into account the transverse relaxation rates in gray matter. We fit our diffusion model to the diffusion-weighted MR signal obtained from cortical gray matter in healthy subjects. Our model includes variable volume fractions, intracellular restriction effects, and exchange between compartments in addition to individual diffusion coefficients and transverse relaxation rates for each compartment. A global optimum was found from a wide range of parameter permutations using cluster computing. We also present simulations of cell swelling and changes of exchange rate and intracellular diffusion as possible cellular mechanisms in ischemia. Our model estimates an extracellular volume fraction of 0.19 in accordance with the accepted value from histology. The absolute apparent diffusion coefficient obtained from the model was similar to that of experiments. The model and the experimental results indicate significant differences in diffusion and transverse relaxation between the tissue compartments and slow water exchange. Our model reproduces the signal changes observed in ischemia via physiologically credible mechanisms. Our modeling suggests that transverse relaxation has a profound influence on the diffusion attenuated MR signal. Our simulations indicate cell swelling as the primary cause of the diffusion changes seen in the acute phase of brain ischemia. (c) 2007 Wiley-Liss, Inc.

  9. Baryon symmetric big bang cosmology

    Science.gov (United States)

    Stecker, F. W.

    1978-01-01

    Both the quantum theory and Einsteins theory of special relativity lead to the supposition that matter and antimatter were produced in equal quantities during the big bang. It is noted that local matter/antimatter asymmetries may be reconciled with universal symmetry by assuming (1) a slight imbalance of matter over antimatter in the early universe, annihilation, and a subsequent remainder of matter; (2) localized regions of excess for one or the other type of matter as an initial condition; and (3) an extremely dense, high temperature state with zero net baryon number; i.e., matter/antimatter symmetry. Attention is given to the third assumption, which is the simplest and the most in keeping with current knowledge of the cosmos, especially as pertains the universality of 3 K background radiation. Mechanisms of galaxy formation are discussed, whereby matter and antimatter might have collided and annihilated each other, or have coexisted (and continue to coexist) at vast distances. It is pointed out that baryon symmetric big bang cosmology could probably be proved if an antinucleus could be detected in cosmic radiation.

  10. Constraints on the Galactic Halo Dark Matter from Fermi-LAT Diffuse Measurements

    Science.gov (United States)

    Ackermann, M.; Ajello, M.; Atwood, W. B.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Blandford, R. D.; Bloom, E. D.; hide

    2012-01-01

    We have performed an analysis of the diffuse gamma-ray emission with the Fermi Large Area Telescope (LAT) in the Milky Way halo region, searching for a signal from dark matter annihilation or decay. In the absence of a robust dark matter signal, constraints are presented. We consider both gamma rays produced directly in the dark matter annihilation/decay and produced by inverse Compton scattering of the e+/e- produced in the annihilation/decay. Conservative limits are derived requiring that the dark matter signal does not exceed the observed diffuse gamma-ray emission. A second set of more stringent limits is derived based on modeling the foreground astrophysical diffuse emission using the GALPROP code. Uncertainties in the height of the diffusive cosmic-ray halo, the distribution of the cosmic-ray sources in the Galaxy, the index of the injection cosmic-ray electron spectrum, and the column density of the interstellar gas are taken into account using a profile likelihood formalism, while the parameters governing the cosmic-ray propagation have been derived from fits to local cosmic-ray data. The resulting limits impact the range of particle masses over which dark matter thermal production in the early universe is possible, and challenge the interpretation of the PAMELA/Fermi-LAT cosmic ray anomalies as the annihilation of dark matter.

  11. Baryon-baryon mixing in hypernuclei

    International Nuclear Information System (INIS)

    Gibson, B.F.

    1998-01-01

    Implications of few-body hypernuclei for the understanding of the baryon-baryon interaction are examined. Octet-octet coupling effects not present in conventional, non strange nuclei are the focus. The need to identify strangeness -2 hypernuclei to test model predictions is emphasized

  12. A voxel-based diffusion tensor imaging study of white matter in bipolar disorder.

    Science.gov (United States)

    Mahon, Katie; Wu, Jinghui; Malhotra, Anil K; Burdick, Katherine E; DeRosse, Pamela; Ardekani, Babak A; Szeszko, Philip R

    2009-05-01

    There is evidence from post-mortem and magnetic resonance imaging studies that hyperintensities, oligodendroglial abnormalities, and gross white matter volumetric alterations are involved in the pathophysiology of bipolar disorder. There is also functional imaging evidence for a defect in frontal cortico-subcortical pathways in bipolar disorder, but the white matter comprising these pathways has not been well investigated. Few studies have investigated white matter integrity in patients with bipolar disorder compared to healthy volunteers and the majority of studies have used manual region-of-interest approaches. In this study, we compared fractional anisotropy (FA) values between 30 patients with bipolar disorder and 38 healthy volunteers in the brain white matter using a voxelwise analysis following intersubject registration to Talairach space. Compared to healthy volunteers, patients demonstrated significantly (p or =50) higher FA within the right and left frontal white matter and lower FA within the left cerebellar white matter. Examination of individual eigenvalues indicated that group differences in both axial diffusivity and radial diffusivity contributed to abnormal FA within these regions. Tractography was performed in template space on averaged diffusion tensor imaging data from all individuals. Extraction of bundles passing through the clusters that differed significantly between groups suggested that white matter abnormalities along the pontine crossing tract, corticospinal/corticopontine tracts, and thalamic radiation fibers may be involved in the pathogenesis of bipolar disorder. Our findings are consistent with models of bipolar disorder that implicate dysregulation of cortico-subcortical and cerebellar regions in the disorder and may have relevance for phenomenology.

  13. Baryon stopping and strangeness baryon production in a parton cascade model

    International Nuclear Information System (INIS)

    Nara, Yasushi

    1999-01-01

    A parton cascade model which is based on pQCD incorporating hard partonic scattering and dynamical hadronization scheme describes the space-time evolution of parton/hadron system produced by ultra-relativistic nuclear collisions. Hadron yield, baryon stopping and transverse momentum distribution are calculated and compared with experimental data at SPS energies. Using new version of parton cascade code VNI in which baryonic cluster formation is implemented, we calculate the net baryon number distributions and Λ yield. It is found that baryon stopping behavior at SPS energies is well accounted for within the parton cascade picture. As a consequence of the production of the baryon (u and d quark) rich parton matter, parton coalescence naturally explains the enhanced yield of Λ particle which has been observed in experiment. (author)

  14. White matter microstructure in transsexuals and controls investigated by diffusion tensor imaging.

    Science.gov (United States)

    Kranz, Georg S; Hahn, Andreas; Kaufmann, Ulrike; Küblböck, Martin; Hummer, Allan; Ganger, Sebastian; Seiger, Rene; Winkler, Dietmar; Swaab, Dick F; Windischberger, Christian; Kasper, Siegfried; Lanzenberger, Rupert

    2014-11-12

    Biological causes underpinning the well known gender dimorphisms in human behavior, cognition, and emotion have received increased attention in recent years. The advent of diffusion-weighted magnetic resonance imaging has permitted the investigation of the white matter microstructure in unprecedented detail. Here, we aimed to study the potential influences of biological sex, gender identity, sex hormones, and sexual orientation on white matter microstructure by investigating transsexuals and healthy controls using diffusion tensor imaging (DTI). Twenty-three female-to-male (FtM) and 21 male-to-female (MtF) transsexuals, as well as 23 female (FC) and 22 male (MC) controls underwent DTI at 3 tesla. Fractional anisotropy, axial, radial, and mean diffusivity were calculated using tract-based spatial statistics (TBSS) and fiber tractography. Results showed widespread significant differences in mean diffusivity between groups in almost all white matter tracts. FCs had highest mean diffusivities, followed by FtM transsexuals with lower values, MtF transsexuals with further reduced values, and MCs with lowest values. Investigating axial and radial diffusivities showed that a transition in axial diffusivity accounted for mean diffusivity results. No significant differences in fractional anisotropy maps were found between groups. Plasma testosterone levels were strongly correlated with mean, axial, and radial diffusivities. However, controlling for individual estradiol, testosterone, or progesterone plasma levels or for subjects' sexual orientation did not change group differences. Our data harmonize with the hypothesis that fiber tract development is influenced by the hormonal environment during late prenatal and early postnatal brain development. Copyright © 2014 the authors 0270-6474/14/3415466-10$15.00/0.

  15. White Matter Microstructure in Transsexuals and Controls Investigated by Diffusion Tensor Imaging

    Science.gov (United States)

    Kranz, Georg S.; Hahn, Andreas; Kaufmann, Ulrike; Küblböck, Martin; Hummer, Allan; Ganger, Sebastian; Seiger, Rene; Winkler, Dietmar; Swaab, Dick F.; Windischberger, Christian; Kasper, Siegfried; Lanzenberger, Rupert

    2015-01-01

    Biological causes underpinning the well known gender dimorphisms in human behavior, cognition, and emotion have received increased attention in recent years. The advent of diffusion-weighted magnetic resonance imaging has permitted the investigation of the white matter microstructure in unprecedented detail. Here, we aimed to study the potential influences of biological sex, gender identity, sex hormones, and sexual orientation on white matter microstructure by investigating transsexuals and healthy controls using diffusion tensor imaging (DTI). Twenty-three female-to-male (FtM) and 21 male-to-female (MtF) transsexuals, as well as 23 female (FC) and 22 male (MC) controls underwent DTI at 3 tesla. Fractional anisotropy, axial, radial, and mean diffusivity were calculated using tract-based spatial statistics (TBSS) and fiber tractography. Results showed widespread significant differences in mean diffusivity between groups in almost all white matter tracts. FCs had highest mean diffusivities, followed by FtM transsexuals with lower values, MtF transsexuals with further reduced values, and MCs with lowest values. Investigating axial and radial diffusivities showed that a transition in axial diffusivity accounted for mean diffusivity results. No significant differences in fractional anisotropy maps were found between groups. Plasma testosterone levels were strongly correlated with mean, axial, and radial diffusivities. However, controlling for individual estradiol, testosterone, or progesterone plasma levels or for subjects’ sexual orientation did not change group differences. Our data harmonize with the hypothesis that fiber tract development is influenced by the hormonal environment during late prenatal and early postnatal brain development. PMID:25392513

  16. White matter injury in newborns with congenital heart disease: a diffusion tensor imaging study.

    Science.gov (United States)

    Mulkey, Sarah B; Ou, Xiawei; Ramakrishnaiah, Raghu H; Glasier, Charles M; Swearingen, Christopher J; Melguizo, Maria S; Yap, Vivien L; Schmitz, Michael L; Bhutta, Adnan T

    2014-09-01

    Brain injury is observed on cranial magnetic resonance imaging preoperatively in up to 50% of newborns with congenital heart disease. Newer imaging techniques such as diffusion tensor imaging provide sensitive measures of the white matter integrity. The objective of this study was to evaluate the diffusion tensor imaging analysis technique of tract-based spatial statistics in newborns with congenital heart disease. Term newborns with congenital heart disease who would require surgery at less than 1 month of age were prospectively enrolled (n = 19). Infants underwent preoperative and postoperative brain magnetic resonance imaging with diffusion tensor imaging. Tract-based spatial statistics, an objective whole-brain diffusion tensor imaging analysis technique, was used to determine differences in white matter fractional anisotropy between infant groups. Term control infants were also compared with congenital heart disease infants. Postmenstrual age was equivalent between congenital heart disease infant groups and between congenital heart disease and control infants. Ten infants had preoperative brain injury, either infarct or white matter injury, by conventional brain magnetic resonance imaging. The technique of tract-based spatial statistics showed significantly lower fractional anisotropy (P tensor imaging analysis technique that may have better sensitivity in detecting white matter injury compared with conventional brain magnetic resonance imaging in term newborns with congenital heart disease. Copyright © 2014 Elsevier Inc. All rights reserved.

  17. MRI of paraventricular white matter lesions in amyotrophic lateral sclerosis. Analysis by diffusion-weighted images

    Energy Technology Data Exchange (ETDEWEB)

    Segawa, Fuminori; Kinoshita, Masao (Toho Univ., Tokyo (Japan). Ohashi Hospital); Kishibayashi, Jun; Kamada, Kazuhiko; Sunohara, Nobuhiko

    1994-09-01

    Magnetic resonance images in some cases of amyotrophic lateral sclerosis (ALS) revealed abnormal signals in both the paraventriculer white matter and in the posterior limbs of the internal capsule. We examined T[sub 2]- and diffusion-weighted MR images of these lesions in 18 cases of ALS. There were symmetrical high-signal areas in the posterior limbs of the internal capsule in all of the cases. The high-signal areas in the internal capsule corresponded to the pyramidal tracts in the anatomical atlas by Talairach. In 5 of the cases of ALS, T[sub 2]-weighted MR images showed discrete paraventricular white matter lesions as well. The mean age of the ALS patients with paraventricular white matter lesions was higher than that of the ALS patients without such lesions. Proton densities calculated from the conventional MR images were higher in both the capsular and paraventricular lesions. The diffusion coefficients perpendicular to the pyramidal tract in the internal capsular lesions were within the normal range, where as the diffusion coefficients in the paraventricular lesions were increased in all directions. Thus, diffusion anisotropy was lost in the paraventricular lesions. These findings are similar to those observed in the white matter lesions of cerebro-vascular origin. As a result, the pathology of the paraventricular lesions in ALS was confirmed to be different from that of the internal capsular lesions. (author).

  18. MRI of paraventricular white matter lesions in amyotrophic lateral sclerosis. Analysis by diffusion-weighted images

    International Nuclear Information System (INIS)

    Segawa, Fuminori; Kinoshita, Masao; Kishibayashi, Jun; Kamada, Kazuhiko; Sunohara, Nobuhiko.

    1994-01-01

    Magnetic resonance images in some cases of amyotrophic lateral sclerosis (ALS) revealed abnormal signals in both the paraventriculer white matter and in the posterior limbs of the internal capsule. We examined T 2 - and diffusion-weighted MR images of these lesions in 18 cases of ALS. There were symmetrical high-signal areas in the posterior limbs of the internal capsule in all of the cases. The high-signal areas in the internal capsule corresponded to the pyramidal tracts in the anatomical atlas by Talairach. In 5 of the cases of ALS, T 2 -weighted MR images showed discrete paraventricular white matter lesions as well. The mean age of the ALS patients with paraventricular white matter lesions was higher than that of the ALS patients without such lesions. Proton densities calculated from the conventional MR images were higher in both the capsular and paraventricular lesions. The diffusion coefficients perpendicular to the pyramidal tract in the internal capsular lesions were within the normal range, where as the diffusion coefficients in the paraventricular lesions were increased in all directions. Thus, diffusion anisotropy was lost in the paraventricular lesions. These findings are similar to those observed in the white matter lesions of cerebro-vascular origin. As a result, the pathology of the paraventricular lesions in ALS was confirmed to be different from that of the internal capsular lesions. (author)

  19. Diffuse X-ray emission from the NGC 2300 group of galaxies - Implications for dark matter and galaxy evolution in small groups

    Science.gov (United States)

    Mulchaey, John S.; Davis, David S.; Mushotzky, Richard F.; Burstein, David

    1993-01-01

    The discovery of diffuse X-ray emission from the NGC 2300 group of galaxies using the ROSAT Position Sensitive Proportional Counter is reported. The gas distributions is roughly symmetric and extends to a radius of at least 0.2/h(50) Mpc. A Raymond-Smith hot plasma model provides an excellent fit the X-ray spectrum with a best-fit value temperature of 0.9 + -/15 or - 0.14 keV and abundance 0.06 + 0/.12 or - 0.05 solar. The assumption of gravitational confinement leads to a total mass of the group of 3.0 + 0.4 or - 0.5 x 10 exp 13 solar. Baryons can reasonably account for 4 percent of this mass, and errors could push this number not higher than 10-15 percent. This is one of the strongest pieces of evidence that dark matter dominates small groups such as this one. The intragroup medium in this system has the lowest metal abundance yet found in diffuse gas in a group or cluster.

  20. Non-linear diffusion and pattern formation in vortex matter

    Science.gov (United States)

    Wijngaarden, Rinke J.; Surdeanu, R.; Huijbregtse, J. M.; Rector, J. H.; Dam, B.; Griessen, R.; Einfeld, J.; Woerdenweber, R.

    2000-03-01

    Penetration of magnetic flux in YBa_2Cu_3O7 superconducting thin films and crystals in externally applied magnetic fields is visualized with a magneto-optical technique. A variety of flux patterns due to non-linear vortex behavior is observed: 1. Roughening of the flux front^1 with scaling exponents identical to those observed in burning paper^2. Two regimes are found where respectively spatial disorder and temporal disorder dominate. In the latter regime Kardar-Parisi-Zhang behavior is found. 2. Roughening of the flux profile similar to the Oslo model for rice-piles. 3. Fractal penetration of flux^3 with Hausdorff dimension depending on the critical current anisotropy. 4. Penetration as 'flux-rivers'. 5. The occurrence of commensurate and incommensurate channels in films with anti-dots as predicted in numerical simulations by Reichhardt, Olson and Nori^4. By comparison with numerical simulations, it is shown that most of the observed behavior can be explained in terms of non-linear diffusion of vortices. ^1R. Surdeanu, R.J. Wijngaarden, E. Visser, J.M. Huijbregtse, J.H. Rector, B. Dam and R. Griessen, Phys.Rev. Lett. 83 (1999) 2054 ^2J. Maunuksela, M. Myllys, O.-P. Kähkönen, J. Timonen, N. Provatas, M.J. Alava, T. Ala-Nissila, Phys. Rev. Lett. 79, 1515 (1997) ^3R. Surdeanu, R.J. Wijngaarden, B. Dam, J. Rector, R. Griessen, C. Rossel, Z.F. Ren and J.H. Wang, Phys Rev B 58 (1998) 12467 ^4C. Reichhardt, C.J. Olson and F. Nori, Phys. Rev. B 58, 6534 (1998)

  1. The cosmic history of the baryon budget in a hierarchical universe

    International Nuclear Information System (INIS)

    Rasera, Yann

    2005-01-01

    In the framework of the hierarchical model of galaxy formation, small primordial density fluctuations observed on the cosmological microwave background are amplified by gravitational instability leading to the formation of larger and larger halos. The gas collapses and cools in these dark matter potential wells and forms cold centrifugally supported gas discs. These discs are converted into stellar discs that is to say galaxies. The problem in this scenario is the so-called 'overcooling problem': the resulting amount of stars is greater than the observed one by a factor of four. I have therefore studied the evolution of baryons (hydrogen and helium gas) in the Universe using high resolution hydrodynamic simulations. Based on these results, I have developed a simple analytical model for computing the baryons mass fraction in each of the following phases: stars, cold gas in galactic discs, hot gas in clusters and diffuse gas in the intergalactic medium. The comparison of model results to observations shows us that cosmology controls the cosmic history of star formation. The important cosmological role of galactic winds is also shed to light. They eject the cold gas from discs to hot halos, overcoming the overcooling problem. Finally, I have studied the implication of baryon physics onto the diffuse gamma-ray background from light dark matter particles. (author) [fr

  2. Strategies for dark matter detection

    International Nuclear Information System (INIS)

    Silk, J.

    1988-01-01

    The present status of alternative forms of dark matter, both baryonic and nonbaryonic, is reviewed. Alternative arguments are presented for the predominance of either cold dark matter (CDM) or of baryonic dark matter (BDM). Strategies are described for dark matter detection, both for dark matter that consists of weakly interacting relic particles and for dark matter that consists of dark stellar remnants

  3. Effect of antenatal growth and prematurity on brain white matter: diffusion tensor study

    Energy Technology Data Exchange (ETDEWEB)

    Lepomaeki, V. [Turku University Central Hospital, Medical Imaging Centre of Southwest Finland, Turku (Finland); Turku University Central Hospital, Turku PET-Centre, PO Box 52, Turku (Finland); Paavilainen, T.; Komu, M. [Turku University Central Hospital, Medical Imaging Centre of Southwest Finland, Turku (Finland); Matomaeki, J.; Lapinleimu, H.; Liisa Lehtonen, L. [Turku University Central Hospital and University of Turku, Department of Pediatrics, Turku (Finland); Hurme, S. [University of Turku, Department of Biostatistics, Turku (Finland); Haataja, L. [Turku University Central Hospital and University of Turku, Department of Pediatric Neurology, Turku (Finland); Parkkola, R. [Turku University Central Hospital, Medical Imaging Centre of Southwest Finland, Turku (Finland); Turku University Central Hospital, Turku PET-Centre, PO Box 52, Turku (Finland); University of Turku, Department of Diagnostic Radiology, Turku (Finland)

    2012-06-15

    White matter maturation is characterised by increasing fractional anisotropy (FA) and decreasing mean diffusivity (MD). Contradictory results have been published on the effect of premature birth on white matter maturation at term-equivalent age. To assess the association of gestational age and low birth-weight-for-gestational-age (z-score) with white matter maturation. Infants (n = 76, 53 males) born at different gestational ages were imaged at term-equivalent age. Gestational age and birth weight z-score were used as continuous variables and the effect on diffusion parameters was assessed. Brain maturation was studied using regions-of-interest analysis in several white matter areas. Gestational age showed no significant effect on white matter maturation at term-equivalent age. Children with low birth weight z-score had lower FA in the genu and splenium of the corpus callosum (regression, P = 0.012 and P = 0.032; correlation, P = 0.009 and P = 0.006, respectively), and higher MD in the splenium of the corpus callosum (regression, P = 0.002; correlation, P = 0.0004) compared to children whose birth weight was appropriate for gestational age. Children with low birth weight relative to gestational age show delay and/or anomaly in white matter maturation at term-equivalent age. (orig.)

  4. Effect of antenatal growth and prematurity on brain white matter: diffusion tensor study

    International Nuclear Information System (INIS)

    Lepomaeki, V.; Paavilainen, T.; Komu, M.; Matomaeki, J.; Lapinleimu, H.; Liisa Lehtonen, L.; Hurme, S.; Haataja, L.; Parkkola, R.

    2012-01-01

    White matter maturation is characterised by increasing fractional anisotropy (FA) and decreasing mean diffusivity (MD). Contradictory results have been published on the effect of premature birth on white matter maturation at term-equivalent age. To assess the association of gestational age and low birth-weight-for-gestational-age (z-score) with white matter maturation. Infants (n = 76, 53 males) born at different gestational ages were imaged at term-equivalent age. Gestational age and birth weight z-score were used as continuous variables and the effect on diffusion parameters was assessed. Brain maturation was studied using regions-of-interest analysis in several white matter areas. Gestational age showed no significant effect on white matter maturation at term-equivalent age. Children with low birth weight z-score had lower FA in the genu and splenium of the corpus callosum (regression, P = 0.012 and P = 0.032; correlation, P = 0.009 and P = 0.006, respectively), and higher MD in the splenium of the corpus callosum (regression, P = 0.002; correlation, P = 0.0004) compared to children whose birth weight was appropriate for gestational age. Children with low birth weight relative to gestational age show delay and/or anomaly in white matter maturation at term-equivalent age. (orig.)

  5. Revealing dark matter substructure with anisotropies in the diffuse gamma-ray background

    Energy Technology Data Exchange (ETDEWEB)

    Siegal-Gaskins, Jennifer M, E-mail: jsg@kicp.uchicago.edu [Kavli Institute for Cosmological Physics and Department of Physics, University of Chicago, 5640 S. Ellis Avenue, Chicago, IL 60637 (United States)

    2008-10-15

    The majority of gamma-ray emission from galactic dark matter annihilation is likely to be detected as a contribution to the diffuse gamma-ray background. I show that dark matter substructure in the halo of the Galaxy induces characteristic anisotropies in the diffuse background that could be used to determine the small-scale dark matter distribution. I calculate the angular power spectrum of the emission from dark matter substructure for several models of the subhalo population and show that features in the power spectrum can be used to infer the presence of substructure. The shape of the power spectrum is largely unaffected by the subhalo radial distribution and mass function, and for many scenarios I find that a measurement of the angular power spectrum by Fermi will be able to constrain the abundance of substructure. An anti-biased subhalo radial distribution is shown to produce emission that differs significantly in intensity and large-scale angular dependence from that of a subhalo distribution which traces the smooth dark matter halo, potentially impacting the detectability of the dark matter signal for a variety of targets and methods.

  6. Revealing dark matter substructure with anisotropies in the diffuse gamma-ray background

    International Nuclear Information System (INIS)

    Siegal-Gaskins, Jennifer M

    2008-01-01

    The majority of gamma-ray emission from galactic dark matter annihilation is likely to be detected as a contribution to the diffuse gamma-ray background. I show that dark matter substructure in the halo of the Galaxy induces characteristic anisotropies in the diffuse background that could be used to determine the small-scale dark matter distribution. I calculate the angular power spectrum of the emission from dark matter substructure for several models of the subhalo population and show that features in the power spectrum can be used to infer the presence of substructure. The shape of the power spectrum is largely unaffected by the subhalo radial distribution and mass function, and for many scenarios I find that a measurement of the angular power spectrum by Fermi will be able to constrain the abundance of substructure. An anti-biased subhalo radial distribution is shown to produce emission that differs significantly in intensity and large-scale angular dependence from that of a subhalo distribution which traces the smooth dark matter halo, potentially impacting the detectability of the dark matter signal for a variety of targets and methods

  7. Microstructural changes in ischemic cortical gray matter predicted by a model of diffusion-weighted MRI

    DEFF Research Database (Denmark)

    Vestergaard-Poulsen, Peter; Hansen, Brian; Østergaard, Leif

    2007-01-01

    compartment. A global optimum was found from a wide range of parameter permutations using cluster computing. We also present simulations of cell swelling and changes of exchange rate and intracellular diffusion as possible cellular mechanisms in ischemia. RESULTS: Our model estimates an extracellular volume...... compartments and slow water exchange. Our model reproduces the signal changes observed in ischemia via physiologically credible mechanisms. CONCLUSION: Our modeling suggests that transverse relaxation has a profound influence on the diffusion attenuated MR signal. Our simulations indicate cell swelling...... model to the diffusion-weighted MR signal obtained from cortical gray matter in healthy subjects. Our model includes variable volume fractions, intracellular restriction effects, and exchange between compartments in addition to individual diffusion coefficients and transverse relaxation rates for each...

  8. Baryon superfluids in AdS/CFT with flavor

    Energy Technology Data Exchange (ETDEWEB)

    Hoyos, Carlos [Department of Physics, Universidad de Oviedo,Avda. Calvo Sotelo 18, ES-33007 Oviedo (Spain); Itsios, Georgios [Department of Physics, Universidad de Oviedo,Avda. Calvo Sotelo 18, ES-33007 Oviedo (Spain); Instituto de Física Teórica, UNESP-Universidade Estadual Paulista,R. Dr. Bento T. Ferraz 271, Bl. II, Sao Paulo 01140-070, SP (Brazil); Vasilakis, Orestis [Department of Physics, Universidad de Oviedo,Avda. Calvo Sotelo 18, ES-33007 Oviedo (Spain)

    2017-01-31

    Baryonic matter is notoriously difficult to deal with in the large-N limit, as baryons become operators of very large dimension with N fields in the fundamental representation. This issue is also present in gauge/gravity duals as baryons are described by very heavy localized objects. There are however alternative large-N extrapolations of QCD where small baryonic operators exist and can be treated on an equal footing to mesons. We explore the possibility of turning on a finite density of “light” baryons in a theory with a hadronic mass gap using a gauge/gravity construction based on the D3/D7 intersection. We find a novel phase with spontaneous breaking of baryon symmetry at zero temperature.

  9. Anatomical and diffusion MRI of deep gray matter in pediatric spina bifida

    Directory of Open Access Journals (Sweden)

    Ashley L. Ware

    2014-01-01

    Full Text Available Individuals with spina bifida myelomeningocele (SBM exhibit brain abnormalities in cortical thickness, white matter integrity, and cerebellar structure. Little is known about deep gray matter macro- and microstructure in this population. The current study utilized volumetric and diffusion-weighted MRI techniques to examine gray matter volume and microstructure in several subcortical structures: basal ganglia nuclei, thalamus, hippocampus, and amygdala. Sixty-six children and adolescents (ages 8–18; M = 12.0, SD = 2.73 with SBM and typically developing (TD controls underwent T1- and diffusion-weighted neuroimaging. Microstructural results indicated that hippocampal volume was disproportionately reduced, whereas the putamen volume was enlarged in the group with SBM. Microstructural analyses indicated increased mean diffusivity (MD and fractional anisotropy (FA in the gray matter of most examined structures (i.e., thalamus, caudate, hippocampus, with the putamen exhibiting a unique pattern of decreased MD and increased FA. These results provide further support that SBM differentially disrupts brain regions whereby some structures are volumetrically normal whereas others are reduced or enlarged. In the hippocampus, volumetric reduction coupled with increased MD may imply reduced cellular density and aberrant organization. Alternatively, the enlarged volume and significantly reduced MD in the putamen suggest increased density.

  10. The baryon content of the Cosmic Web

    Science.gov (United States)

    Eckert, Dominique; Jauzac, Mathilde; Shan, HuanYuan; Kneib, Jean-Paul; Erben, Thomas; Israel, Holger; Jullo, Eric; Klein, Matthias; Massey, Richard; Richard, Johan; Tchernin, Céline

    2015-01-01

    Big-Bang nucleosynthesis indicates that baryons account for 5% of the Universe’s total energy content[1]. In the local Universe, the census of all observed baryons falls short of this estimate by a factor of two[2,3]. Cosmological simulations indicate that the missing baryons have not yet condensed into virialised halos, but reside throughout the filaments of the cosmic web: a low-density plasma at temperature 105–107 K known as the warm-hot intergalactic medium (WHIM)[3,4,5,6]. There have been previous claims of the detection of warm baryons along the line of sight to distant blazars[7,8,9,10] and hot gas between interacting clusters[11,12,13,14]. These observations were however unable to trace the large-scale filamentary structure, or to estimate the total amount of warm baryons in a representative volume of the Universe. Here we report X-ray observations of filamentary structures of ten-million-degree gas associated with the galaxy cluster Abell 2744. Previous observations of this cluster[15] were unable to resolve and remove coincidental X-ray point sources. After subtracting these, we reveal hot gas structures that are coherent over 8 Mpc scales. The filaments coincide with over-densities of galaxies and dark matter, with 5-10% of their mass in baryonic gas. This gas has been heated up by the cluster's gravitational pull and is now feeding its core. PMID:26632589

  11. The baryonic mass function of galaxies.

    Science.gov (United States)

    Read, J I; Trentham, Neil

    2005-12-15

    In the Big Bang about 5% of the mass that was created was in the form of normal baryonic matter (neutrons and protons). Of this about 10% ended up in galaxies in the form of stars or of gas (that can be in molecules, can be atomic, or can be ionized). In this work, we measure the baryonic mass function of galaxies, which describes how the baryonic mass is distributed within galaxies of different types (e.g. spiral or elliptical) and of different sizes. This can provide useful constraints on our current cosmology, convolved with our understanding of how galaxies form. This work relies on various large astronomical surveys, e.g. the optical Sloan Digital Sky Survey (to observe stars) and the HIPASS radio survey (to observe atomic gas). We then perform an integral over our mass function to determine the cosmological density of baryons in galaxies: Omega(b,gal)=0.0035. Most of these baryons are in stars: Omega(*)=0.0028. Only about 20% are in gas. The error on the quantities, as determined from the range obtained between different methods, is ca 10%; systematic errors may be much larger. Most (ca 90%) of the baryons in the Universe are not in galaxies. They probably exist in a warm/hot intergalactic medium. Searching for direct observational evidence and deeper theoretical understanding for this will form one of the major challenges for astronomy in the next decade.

  12. Diffusion Tensor Imaging-Based Research on Human White Matter Anatomy

    Directory of Open Access Journals (Sweden)

    Ming-guo Qiu

    2012-01-01

    Full Text Available The aim of this study is to investigate the white matter by the diffusion tensor imaging and the Chinese visible human dataset and to provide the 3D anatomical data of the corticospinal tract for the neurosurgical planning by studying the probabilistic maps and the reproducibility of the corticospinal tract. Diffusion tensor images and high-resolution T1-weighted images of 15 healthy volunteers were acquired; the DTI data were processed using DtiStudio and FSL software. The FA and color FA maps were compared with the sectional images of the Chinese visible human dataset. The probability maps of the corticospinal tract were generated as a quantitative measure of reproducibility for each voxel of the stereotaxic space. The fibers displayed by the diffusion tensor imaging were well consistent with the sectional images of the Chinese visible human dataset and the existing anatomical knowledge. The three-dimensional architecture of the white matter fibers could be clearly visualized on the diffusion tensor tractography. The diffusion tensor tractography can establish the 3D probability maps of the corticospinal tract, in which the degree of intersubject reproducibility of the corticospinal tract is consistent with the previous architectonic report. DTI is a reliable method of studying the fiber connectivity in human brain, but it is difficult to identify the tiny fibers. The probability maps are useful for evaluating and identifying the corticospinal tract in the DTI, providing anatomical information for the preoperative planning and improving the accuracy of surgical risk assessments preoperatively.

  13. Diquark structure of baryons

    International Nuclear Information System (INIS)

    Silvestre-Brac, B.

    1987-01-01

    Three body calculations for studying the baryons are performed in a non-relativistic treatment with three quarks interacting via Bhaduri's potential. From the resulting wave functions, it is analysed under which conditions can a diquark structure occurs. Several photos showing quark distributions inside the baryons are presented and discussed in details

  14. Outlook for baryon spectroscopy

    International Nuclear Information System (INIS)

    Tripp, R.D.

    1976-09-01

    The review of baryon spectroscopy includes a number of new generation experiments with greatly improved statistics which have emerged and are enhancing experimental knowledge of baryon resonances. The future research directions are pointed out, and some problems and deficiencies which can be resolved with contemporary techniques are mentioned

  15. B decays to baryons

    Indian Academy of Sciences (India)

    We note that two-body decays to baryons are suppressed relative to three- and four-body decays. In most of these analyses, the invariant baryon–antibaryon mass shows an enhancement near the threshold. We propose a phenomenological interpretation of this quite common feature of hadronization to baryons.

  16. Baryons and dual unitarization

    International Nuclear Information System (INIS)

    Konishi, K.-I.

    1977-05-01

    Processes involving baryons are discussed in the scheme of dual unitarization. In particular, the topological expansion is generalized to any hadronic S-matrix elements involving baryons and/or mesons. The expansion is based on a model for the baryon propagator, which is a set of three planar Feynman diagrams joined at a junction line. The resulting expansion is a double expansion in 1/N (N = the number of quark flavours) and in the number of baryon loops. Based on this, several new observations are made in phenomenological problems, and a unifying point of view in stressed. The scheme is evidently crossing invariant, and unitarity constraints are imposed order by order in 1/N and in the baryon loop number. (author)

  17. Intra- and interhemispheric variations of diffusivity in subcortical white matter in normal human brain

    International Nuclear Information System (INIS)

    Yoshiura, Takashi; Noguchi, Tomoyuki; Hiwatashi, Akio; Togao, Osamu; Yamashita, Koji; Nagao, Eiki; Kamano, Hironori; Honda, Hiroshi

    2010-01-01

    Our purpose was to reveal potential regional variations in water molecular diffusivity within each cerebral hemisphere and across the right and left hemispheres. Diffusion-weighted images of 44 healthy right-handed adult male subjects were obtained using a diffusion tensor imaging sequence. Mean diffusivity (MD) values in subcortical white matter (WM) within 39 regions in each hemisphere were measured using an automated method. Intrahemispheric comparisons of MDs in subcortical WM were performed among six brain regions (frontal, parietal, occipital and temporal lobes and pre- and postcentral gyri). Interhemispheric comparisons of MDs were performed between the right and left counterparts of the 39 regions. In both hemispheres, diffusivity in the precentral gyrus was lower than those in other regions, while diffusivity in the parietal lobe was higher than others. MD asymmetry in which the left was lower than the right was found in the parietal lobe, middle occipital gyrus, and medial and orbital aspects of the frontal lobe. The converse asymmetry was revealed in the frontal operculum, supplementary motor cortex, temporal lobe, limbic cortices, precuneus and cuneus. Our results revealed significant intra- and interhemispheric regional variations in MD in subcortical WM, which may be related to different densities of axons and myelin sheaths. (orig.)

  18. Intra- and interhemispheric variations of diffusivity in subcortical white matter in normal human brain

    Energy Technology Data Exchange (ETDEWEB)

    Yoshiura, Takashi; Noguchi, Tomoyuki; Hiwatashi, Akio; Togao, Osamu; Yamashita, Koji; Nagao, Eiki; Kamano, Hironori; Honda, Hiroshi [Kyushu University, Department of Clinical Radiology, Graduate School of Medical Sciences, Fukuoka (Japan)

    2010-01-15

    Our purpose was to reveal potential regional variations in water molecular diffusivity within each cerebral hemisphere and across the right and left hemispheres. Diffusion-weighted images of 44 healthy right-handed adult male subjects were obtained using a diffusion tensor imaging sequence. Mean diffusivity (MD) values in subcortical white matter (WM) within 39 regions in each hemisphere were measured using an automated method. Intrahemispheric comparisons of MDs in subcortical WM were performed among six brain regions (frontal, parietal, occipital and temporal lobes and pre- and postcentral gyri). Interhemispheric comparisons of MDs were performed between the right and left counterparts of the 39 regions. In both hemispheres, diffusivity in the precentral gyrus was lower than those in other regions, while diffusivity in the parietal lobe was higher than others. MD asymmetry in which the left was lower than the right was found in the parietal lobe, middle occipital gyrus, and medial and orbital aspects of the frontal lobe. The converse asymmetry was revealed in the frontal operculum, supplementary motor cortex, temporal lobe, limbic cortices, precuneus and cuneus. Our results revealed significant intra- and interhemispheric regional variations in MD in subcortical WM, which may be related to different densities of axons and myelin sheaths. (orig.)

  19. Neutron-antineutron oscillation and baryonic majoron: low scale spontaneous baryon violation

    Energy Technology Data Exchange (ETDEWEB)

    Berezhiani, Zurab [Universita dell' Aquila, Dipartimento delle Scienze Fisiche e Chimiche, L' Aquila (Italy); INFN, Laboratori Nazionali Gran Sasso, L' Aquila (Italy)

    2016-12-15

    We discuss the possibility that baryon number B is spontaneously broken at low scales, of the order of MeV or even smaller, inducing the neutron-antineutron oscillation at the experimentally accessible level. An associated Goldstone particle-baryonic majoron can have observable effects in neutron to antineutron transitions in nuclei or dense nuclear matter. By extending baryon number to an anomaly-free B - L symmetry, the baryo-majoron can be identified with the ordinary majoron associated with the spontaneous breaking of lepton number, and it can have interesting implications for neutrinoless 2β decay with the majoron emission. We also discuss the hypothesis that baryon number can be spontaneously broken by QCD itself via the six-quark condensates. (orig.)

  20. Thalamic diffusion differences related to cognitive function in white matter lesions.

    Science.gov (United States)

    Fernández-Andújar, Marina; Soriano-Raya, Juan José; Miralbell, Júlia; López-Cancio, Elena; Cáceres, Cynthia; Bargalló, Núria; Barrios, Maite; Arenillas, Juan Francisco; Toran, Pere; Alzamora, Maite; Clemente, Imma; Dávalos, Antoni; Mataró, Maria

    2014-05-01

    Cerebral white matter lesions (WMLs) are related to cognitive deficits, probably due to a disruption of frontal-subcortical circuits. We explored thalamic diffusion differences related to white matter lesions (WMLs) and their association with cognitive function in middle-aged individuals. Ninety-six participants from the Barcelona-AsIA Neuropsychology Study were included. Participants were classified into groups based on low grade and high grade of periventricular hyperintensities (PVHs) and deep white matter hyperintensities (DWMHs). Tract-Based Spatial Statistics was used to study thalamic diffusion differences between groups. Mean fractional anisotropy (FA) values in significant areas were calculated for each subject and correlated with cognitive performance. Participants with high-grade PVHs and DWMHs showed lower FA thalamic values compared to those with low-grade PVHs and DWMHs, respectively. Decreased FA thalamic values in high-grade DWMHs, but not high-grade PVH, were related to lower levels of performance in psychomotor speed, verbal fluency, and visuospatial skills. Thalamic diffusion differences are related to lower cognitive function only in participants with high-grade DWMHs. These results support the hypothesis that fronto-subcortical disruption is associated with cognitive function only in DWMHs. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Diffusion tensor MR imaging of white matter integrity in HIV-positive patients with planning deficit

    International Nuclear Information System (INIS)

    Correa, Diogo Goulart; Doring, Thomas M.; Wilner, Nina Ventura; Cabral, Rafael Ferracini; Gasparetto, Emerson Leandro; Zimmermann, Nicolle; Fonseca, Rochele Paz; Leite, Sarah C.B.; Bahia, Paulo R.V.

    2015-01-01

    The aim of this study was to evaluate whether normal controls and human immunodeficiency virus (HIV) patients with and without planning deficits differ on white matter integrity. A total of 34 HIV-positive patients with planning deficits were compared with 13 HIV-positive patients without planning deficits and 19 gender-, age-, and education-matched control subjects. Diffusion tensor imaging (DTI) was performed along 30 noncolinear directions in a 1.5-T scanner. For tract-based spatial statistics analysis, a white matter skeleton was created, and a permutation-based inference with 5000 permutations with a threshold of p < 0.05 was used to identify abnormalities in fractional anisotropy (FA). The median, radial, and axial diffusivities were also projected onto the mean FA skeleton. Compared with controls, HIV-positive patients with planning deficits had decreased FA in bilateral anterior thalamic radiations, bilateral inferior fronto-occiptal fasciculi, genu and splenium of the corpus callosum, bilateral superior longitudinal fascicule, and bilateral uncinate fasciculi. Compared to HIV-positive patients without planning deficits, patients with planning deficits had decreased FA in bilateral anterior thalamic radiations, bilateral inferior fronto-occiptal fasciculi, genu of the corpus callosum, bilateral superior longitudinal fascicule, and right uncinate fascicule. DTI can detect extensive white matter abnormalities in the normal-appearing white matter of HIV-positive patients with planning deficits compared with controls and HIV-positive patients without planning deficits. (orig.)

  2. Diffusion tensor MR imaging of white matter integrity in HIV-positive patients with planning deficit

    Energy Technology Data Exchange (ETDEWEB)

    Correa, Diogo Goulart; Doring, Thomas M.; Wilner, Nina Ventura; Cabral, Rafael Ferracini; Gasparetto, Emerson Leandro [Hospital Universitario Clementino Fraga Filho, Rio de Janeiro, RJ (Brazil); Clinica de Diagnostico por Imagem (CDPI), Rio de Janeiro, RJ (Brazil); Zimmermann, Nicolle; Fonseca, Rochele Paz [Hospital Universitario Clementino Fraga Filho, Rio de Janeiro, RJ (Brazil); Pontifical Catholic University of Rio Grande do Sul, Department of Psychology, Rio Grande do Sul (Brazil); Leite, Sarah C.B.; Bahia, Paulo R.V. [Hospital Universitario Clementino Fraga Filho, Rio de Janeiro, RJ (Brazil)

    2015-05-01

    The aim of this study was to evaluate whether normal controls and human immunodeficiency virus (HIV) patients with and without planning deficits differ on white matter integrity. A total of 34 HIV-positive patients with planning deficits were compared with 13 HIV-positive patients without planning deficits and 19 gender-, age-, and education-matched control subjects. Diffusion tensor imaging (DTI) was performed along 30 noncolinear directions in a 1.5-T scanner. For tract-based spatial statistics analysis, a white matter skeleton was created, and a permutation-based inference with 5000 permutations with a threshold of p < 0.05 was used to identify abnormalities in fractional anisotropy (FA). The median, radial, and axial diffusivities were also projected onto the mean FA skeleton. Compared with controls, HIV-positive patients with planning deficits had decreased FA in bilateral anterior thalamic radiations, bilateral inferior fronto-occiptal fasciculi, genu and splenium of the corpus callosum, bilateral superior longitudinal fascicule, and bilateral uncinate fasciculi. Compared to HIV-positive patients without planning deficits, patients with planning deficits had decreased FA in bilateral anterior thalamic radiations, bilateral inferior fronto-occiptal fasciculi, genu of the corpus callosum, bilateral superior longitudinal fascicule, and right uncinate fascicule. DTI can detect extensive white matter abnormalities in the normal-appearing white matter of HIV-positive patients with planning deficits compared with controls and HIV-positive patients without planning deficits. (orig.)

  3. White matter correlates of cognitive domains in normal aging with diffusion tensor imaging

    Directory of Open Access Journals (Sweden)

    Efrat eSasson

    2013-03-01

    Full Text Available The ability to perform complex as well as simple cognitive tasks engages a network of brain regions that is mediated by the white matter fiber bundles connecting them. Different cognitive tasks employ distinctive white matter fiber bundles. The temporal lobe and its projections subserve a variety of key functions known to deteriorate during aging. In a cohort of 52 healthy subjects (ages 25-82 years, we performed voxel-wise regression analysis correlating performance in higher-order cognitive domains (executive function, information processing speed, and memory with white matter integrity, as measured by diffusion tensor imaging (DTI fiber tracking in the temporal lobe projections (uncinate fasciculus (UF, fornix, cingulum, inferior longitudinal fasciculus (ILF, and superior longitudinal fasciculus (SLF. The fiber tracts were spatially registered and statistical parametric maps were produced to spatially localize the significant correlations. Results showed that performance in the executive function domain is correlated with DTI parameters in the left SLF and right UF; performance in the information processing speed domain is correlated with fractional anisotropy (FA in the left cingulum, left fornix, right and left ILF and SLF; and the memory domain shows significant correlations with DTI parameters in the right fornix, right cingulum, left ILF, left SLF and right UF. These findings suggest that DTI tractography enables anatomical definition of region of interest for correlation of behavioral parameters with diffusion indices, and functionality can be correlated with white matter integrity.

  4. White matter impairments in autism, evidence from voxel-based morphometry and diffusion tensor imaging.

    Science.gov (United States)

    Ke, Xiaoyan; Tang, Tianyu; Hong, Shanshan; Hang, Yueyue; Zou, Bing; Li, Huiguo; Zhou, Zhenyu; Ruan, Zongcai; Lu, Zuhong; Tao, Guotai; Liu, Yijun

    2009-04-10

    This study explored white matter abnormalities in a group of Chinese children with high functioning autism (HFA). Twelve male children with HFA and ten matched typically developing children underwent diffusion tensor imaging (DTI) as well three-dimensional T1-weighted MRI for voxel-based morphometry (VBM). We found a significant decrease of the white matter density in the right frontal lobe, left parietal lobe and right anterior cingulate and a significant increase in the right frontal lobe, left parietal lobe and left cingulate gyrus in the HFA group compared with the control group. The HFA group also had decreased FA in the frontal lobe and left temporal lobe. By combining DT-MRI FA and MRI volumetric analyses based on the VBM model, the results showed consistent white matter abnormalities in a group of Chinese children with HFA.

  5. AGREEMENT BETWEEN THE WHITE MATTER CONNECTIVITY BASED ON THE TENSOR-BASED MORPHOMETRY AND THE VOLUMETRIC WHITE MATTER PARCELLATIONS BASED ON DIFFUSION TENSOR IMAGING

    OpenAIRE

    Kim, Seung-Goo; Lee, Hyekyoung; Chung, Moo K.; Hanson, Jamie L.; Avants, Brian B.; Gee, James C.; Davidson, Richard J.; Pollak, Seth D.

    2012-01-01

    We are interested in investigating white matter connectivity using a novel computational framework that does not use diffusion tensor imaging (DTI) but only uses T1-weighted magnetic resonance imaging. The proposed method relies on correlating Jacobian determinants across different voxels based on the tensor-based morphometry (TBM) framework. In this paper, we show agreement between the TBM-based white matter connectivity and the DTI-based white matter atlas. As an application, altered white ...

  6. Baryons with chromodynamics

    International Nuclear Information System (INIS)

    Isgur, N.

    1981-01-01

    Many of the phenomenological difficulties of the non-relativistic quark model for baryons are overcome when some current prejudices from chromodynamics about quark forces are imposed. The effects of flavour independent confinement, symmetry breaking through quark masses, and colour hyperfine interactions are most prominent, leading to a satisfactory understanding of both the spectroscopy of low-lying baryons and of the signs and magnitudes of baryon couplings. The previously worrisome absence in partial wave analyses of a large number of the states expected in the nonrelativistic quark model is explained in terms of decouplings of the resonances from their elastic channels

  7. Comparison of Multi-Tensor Diffusion Models' Performance for White Matter Integrity Estimation in Chronic Stroke

    Directory of Open Access Journals (Sweden)

    Olena G. Filatova

    2018-04-01

    Full Text Available Better insight into white matter (WM alterations after stroke onset could help to understand the underlying recovery mechanisms and improve future interventions. MR diffusion imaging enables to assess such changes. Our goal was to investigate the relation of WM diffusion characteristics derived from diffusion models of increasing complexity with the motor function of the upper limb. Moreover, we aimed to evaluate the variation of such characteristics across different WM structures of chronic stroke patients in comparison to healthy subjects. Subjects were scanned with a two b-value diffusion-weighted MRI protocol to exploit multiple diffusion models: single tensor, single tensor with isotropic compartment, bi-tensor model, bi-tensor with isotropic compartment. From each model we derived the mean tract fractional anisotropy (FA, mean (MD, radial (RD and axial (AD diffusivities outside the lesion site based on a WM tracts atlas. Asymmetry of these measures was correlated with the Fugl-Meyer upper extremity assessment (FMA score and compared between patient and control groups. Eighteen chronic stroke patients and eight age-matched healthy individuals participated in the study. Significant correlation of the outcome measures with the clinical scores of stroke recovery was found. The lowest correlation of the corticospinal tract FAasymmetry and FMA was with the single tensor model (r = −0.3, p = 0.2 whereas the other models reported results in the range of r = −0.79 ÷ −0.81 and p = 4E-5 ÷ 8E-5. The corticospinal tract and superior longitudinal fasciculus showed most alterations in our patient group relative to controls. Multiple compartment models yielded superior correlation of the diffusion measures and FMA compared to the single tensor model.

  8. Preliminary study of normal changes in brain white matter during childhood with diffusion tensor imaging

    International Nuclear Information System (INIS)

    Xiao Jiangxi; Guo Xuemei; Xie Sheng; Wang Xiaoying; Jiang Xuexiang

    2005-01-01

    Objective: To study the normal changes in brain white matter during childhood by analyzing the anisotropy of different regions and different age groups with diffusion tensor imaging (DTI). Methods: DTI was performed in 89 children (age range from 2 days to 18 years) without brain abnormalities, and the data measured in fractional anisotropy (FA) maps were analyzed statistically. Children less than 6 months were ranged to group 1, 6-12 months to group 2, 1-3 years to group 3, 3-5 years to group 4, 5-8 years to group 5, 8-12 years to group 6, 12-18 years to group 7. Results: (1) There were significant differences in anisotropy (FA values) among different regions of white matter in brain. In group 7, the FA value of corpus callosum was 0.826 ± 0.039, middle cerebellar peduncle 0.678 ± 0.043, frontal white matter 0.489 ± 0.033. (2) The anisotropy among different age group was statistically different, P<0.05. (3) The anisotropy of white matter increased with the increasing of age, and FA values showed positively exponentially correlations with age. Conclusion: DTI shows the structure of white matters in vivo, with which normal changes in brain during childhood can be evaluated. (authors)

  9. Isospin splittings of baryons

    International Nuclear Information System (INIS)

    Varga, Kalman; Genovese, Marco; Richard, Jean-Marc; Silvestre-Brac, Bernard

    1998-01-01

    We discuss the isospin-breaking mass differences among baryons, with particular attention in the charm sector to the Σ c + -Σ c 0 , Σ c ++ -Σ c 0 , and Ξ c + -Ξ c 0 splittings. Simple potential models cannot accommodate the trend of the available data on charm baryons. More precise measurements would offer the possibility of testing how well potential models describe the non-perturbative limit of QCD

  10. Achieving maximum baryon densities

    International Nuclear Information System (INIS)

    Gyulassy, M.

    1984-01-01

    In continuing work on nuclear stopping power in the energy range E/sub lab/ approx. 10 GeV/nucleon, calculations were made of the energy and baryon densities that could be achieved in uranium-uranium collisions. Results are shown. The energy density reached could exceed 2 GeV/fm 3 and baryon densities could reach as high as ten times normal nuclear densities

  11. Phenomenology of Baryon Resonances

    Energy Technology Data Exchange (ETDEWEB)

    Doring, Michael [George Washington Univ., Washington, DC (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Landay, Justin [George Washington Univ., Washington, DC (United States); Mai, Maxim [George Washington Univ., Washington, DC (United States); Molina, Raquel [Univ. of Sao Paulo (Brazil); Ronchen, Deborah [Univ. of Bonn (Germany)

    2018-04-01

    Results for light baryon spectroscopy by different collaborations and the state of the art in the subfield is reviewed. Highlights contain common efforts of different phenomenology groups and the impact of recent high-precision data from ELSA, JLab, MAMI, and other facilities. Questions will be addressed, on one side, of how to proceed to reach conclusive answers in baryon spectroscopy, and, on the other side, how phenomenology can be connected to theory in a meaningful way.

  12. The apparent diffusion coefficient of water in gray and white matter of the infant brain

    DEFF Research Database (Denmark)

    Toft, P B; Leth, H; Peitersen, Birgit

    1996-01-01

    PURPOSE: The purpose was to obtain normal values of the apparent diffusion coefficient (ADC) in the infant brain and to compare ADC maps with T1- and T2-weighted images. METHOD: Diffusion was measured in nine infants with an ECG-gated SE sequence compensated for first-order motion. One axial slice...... it appeared on T1- or T2-weighted images. In gray and white matter, the mean ADC ranged from 0.95 x 10(-9) to 1.76 x 10(-9) m2/s. In the frontal and occipital white matter, in the genu corporis callosi, and in the lentiform nucleus, the ADC decreased with increasing age. The cortex/white matter ratio...... of the ADC increased with age and approached 1 at the age of 30 weeks. CONCLUSION: ADC maps add information to the T1 and T2 images about the size and course of unmyelinated as well as myelinated tracts in the immature brain....

  13. White Matter Compromise of Callosal and Subcortical Fiber Tracts in Children with Autism Spectrum Disorder: A Diffusion Tensor Imaging Study

    Science.gov (United States)

    Shukla, Dinesh K.; Keehn, Brandon; Lincoln, Alan J.; Muller, Ralph-Axel

    2010-01-01

    Objective: Autism spectrum disorder (ASD) is increasingly viewed as a disorder of functional networks, highlighting the importance of investigating white matter and interregional connectivity. We used diffusion tensor imaging (DTI) to examine white matter integrity for the whole brain and for corpus callosum, internal capsule, and middle…

  14. Development, simulation and test of transition radiation detector prototypes for the compressed baryonic matter experiment at the facility for antiproton and ion research

    Energy Technology Data Exchange (ETDEWEB)

    Bergmann, Cyrano S.H.

    2014-07-01

    The focus of this thesis is the development of a Transition Radiation Detector (TRD) for the Compressed Baryonic Matter (CBM) experiment at FAIR. The TRD sub-detector will contribute to the global particle identification and track reconstruction of charged particles. The technical design goal for the TRD is to identify 90% electrons with a maximum pion contamination of 1%. The TRD and Ring Image CHerenkov (RICH) detector should reach a common pion rejection of 10{sup 4}, in order to measure charmonium and low-mass vector mesons. The position resolution should be between 200 and 300 μm in the anode wire direction. The most demanding aspect of the CBM TRD design is the high interaction rate of up to 10{sup 7} Hz resulting in a charged particle rate of up to 100 kHz/cm{sup 2} in the central part of the detector planes at SIS300 conditions. It is crucial to find the optimal radiator detector combination with a minimum material budget to limit scattering and background due to conversions and at the same time reach a sufficient pion rejection and position resolution. In this thesis it is confirmed that a Multi-Wire Proportional Counter (MWPC) with a Xe/CO{sub 2} gas thickness of 12mm provides sufficient absorption probability for TR-photons in combination with self-supporting low density PE foam or micro-structured foil radiators. A continuous investigation aiming at an optimal wire and pad-plane geometry, as well as a minimization of the material budget between active gas and radiator has been presented in hard- and software. A minimum photon absorption cross-section of the entrance window was realized with a thermally stretched aluminized Kapton foil, glued to a G11 support grid support frame. This structure limits the mechanical deformation of the entire window to 1mm/mbar. All MWPC prototypes include two wire planes. A symmetric amplification region of 2 x (3, 3.5 or 4)mm is followed by a short drift region of 6, 5 or 4 mm. The drift region reduces the gain

  15. Development, simulation and test of transition radiation detector prototypes for the compressed baryonic matter experiment at the facility for antiproton and ion research

    International Nuclear Information System (INIS)

    Bergmann, Cyrano S.H.

    2014-01-01

    The focus of this thesis is the development of a Transition Radiation Detector (TRD) for the Compressed Baryonic Matter (CBM) experiment at FAIR. The TRD sub-detector will contribute to the global particle identification and track reconstruction of charged particles. The technical design goal for the TRD is to identify 90% electrons with a maximum pion contamination of 1%. The TRD and Ring Image CHerenkov (RICH) detector should reach a common pion rejection of 10 4 , in order to measure charmonium and low-mass vector mesons. The position resolution should be between 200 and 300 μm in the anode wire direction. The most demanding aspect of the CBM TRD design is the high interaction rate of up to 10 7 Hz resulting in a charged particle rate of up to 100 kHz/cm 2 in the central part of the detector planes at SIS300 conditions. It is crucial to find the optimal radiator detector combination with a minimum material budget to limit scattering and background due to conversions and at the same time reach a sufficient pion rejection and position resolution. In this thesis it is confirmed that a Multi-Wire Proportional Counter (MWPC) with a Xe/CO 2 gas thickness of 12mm provides sufficient absorption probability for TR-photons in combination with self-supporting low density PE foam or micro-structured foil radiators. A continuous investigation aiming at an optimal wire and pad-plane geometry, as well as a minimization of the material budget between active gas and radiator has been presented in hard- and software. A minimum photon absorption cross-section of the entrance window was realized with a thermally stretched aluminized Kapton foil, glued to a G11 support grid support frame. This structure limits the mechanical deformation of the entire window to 1mm/mbar. All MWPC prototypes include two wire planes. A symmetric amplification region of 2 x (3, 3.5 or 4)mm is followed by a short drift region of 6, 5 or 4 mm. The drift region reduces the gain variation due to

  16. AGREEMENT BETWEEN THE WHITE MATTER CONNECTIVITY BASED ON THE TENSOR-BASED MORPHOMETRY AND THE VOLUMETRIC WHITE MATTER PARCELLATIONS BASED ON DIFFUSION TENSOR IMAGING.

    Science.gov (United States)

    Kim, Seung-Goo; Lee, Hyekyoung; Chung, Moo K; Hanson, Jamie L; Avants, Brian B; Gee, James C; Davidson, Richard J; Pollak, Seth D

    2012-01-01

    We are interested in investigating white matter connectivity using a novel computational framework that does not use diffusion tensor imaging (DTI) but only uses T1-weighted magnetic resonance imaging. The proposed method relies on correlating Jacobian determinants across different voxels based on the tensor-based morphometry (TBM) framework. In this paper, we show agreement between the TBM-based white matter connectivity and the DTI-based white matter atlas. As an application, altered white matter connectivity in a clinical population is determined.

  17. The angular power spectrum of the diffuse gamma-ray background as a probe of Galactic dark matter substructure

    OpenAIRE

    Siegal-Gaskins, Jennifer M.

    2009-01-01

    Dark matter annihilation in Galactic substructure produces diffuse gamma-ray emission of remarkably constant intensity across the sky, and in general this signal dominates over the smooth halo signal at angles greater than a few tens of degrees from the Galactic Center. The large-scale isotropy of the emission from substructure suggests that it may be difficult to extract this Galactic dark matter signal from the extragalactic gamma-ray background. I show that dark matter substructure induces...

  18. Contribution to the study of the mechanisms of turbulent diffusion and of related matters

    International Nuclear Information System (INIS)

    Mailliat, Alain.

    1980-12-01

    The subject of this paper is the study of turbulent diffusion mechanisms and the related problems. The diffusion mechanisms considered here are those which concern a passive scalar contaminant not subject to molecular effects. The reason for this latter character is that it makes it possible to isolate in the diffusion phenomenon that which is inherent in the turbulent dispersion. The present state of this question is reviewed in Chapter I. The system of natural coordinates for following the movement of a particle and hence for describing the dispersion is that of Lagrange. For our purpose this description must be statistical. Hence, the specific properties of the probability densities of the velocities and movements in this type of coordinate are examined in Chapter II. The expressions of the probability densities of the concentration and turbulent flow of a contaminant are sought. These expressions make it possible to formulate the diffusion laws linking the mean flow and concentration to the statistical characteristics of the velocity field. These matters form the central subject of this paper and are developed in Chapter III. Although the use of Lagrange's coordinates makes it possible fairly easily to obtain the probability densities mentioned above, it does, on the other hand, rule out on examination the relations existing between Lagrangian and Eulerian probability characteristics of the velocity field moments. The experimental determination in a Lagrangian system of the probability characteristics is in fact very tricky. These questions are discussed in Chapter IV of this paper [fr

  19. Mapping of ApoE4 related white matter damage using diffusion MRI

    Science.gov (United States)

    Tsao, Sinchai; Gajawelli, Niharika; Hwang, Darryl H.; Kriger, Stephen; Law, Meng; Chui, Helena; Weiner, Michael; Lepore, Natasha

    2014-04-01

    ApoliopoproteinE Ɛ4 (ApoE-Ɛ4) polymorphism is the most well known genetic risk factor for developing Alzheimers Disease. The exact mechanism through which ApoE 4 increases AD risk is not fully known, but may be related to decreased clearance and increased oligomerization of Aβ. By making measurements of white matter integrity via diffusion MR and correlating the metrics in a voxel-based statistical analysis with ApoE-Ɛ4 genotype (whilst controlling for vascular risk factor, gender, cognitive status and age) we are able to identify changes in white matter associated with carrying an ApoE Ɛ4 allele. We found potentially significant regions (Puncorrected cognitive decline via a pathway in dependent of normal aging and acute insults that can be measured by CDR and Framingham Coronary Risk Score (FCRS).

  20. White matter structure and clinical characteristics of stroke patients: A diffusion tensor MRI study.

    Science.gov (United States)

    Ueda, Ryo; Yamada, Naoki; Kakuda, Wataru; Abo, Masahiro; Senoo, Atsushi

    2016-03-15

    Fractional anisotropy has been used in many studies that examined post-stroke changes in white matter. This study was performed to clarify cerebral white matter changes after stroke using generalized fractional anisotropy (GFA). White matter structure was visualized using diffusion tensor imaging in 72 patients with post-stroke arm paralysis. Exercise-related brain regions were examined in cerebral white matter using GFA. The relationship between GFA and clinical characteristics was examined. Overall, the mean GFA of the lesioned hemisphere was significantly lower than that of the non-lesioned hemisphere (PBrodmann area 5 of the non-lesioned hemisphere. Age correlated negatively with GFA in Brodmann areas 5 and 7 of the lesioned hemisphere. Though these results may be due to a decrease in the frequency of use of the paralyzed limb over time, GFA overall was significantly and negatively affected by the subject's age. The GFA values of patients with paralysis of the dominant hand were significantly different from those of patients with paralysis of the nondominant hand in Brodmann areas 4 and 6 of the non-lesioned hemisphere and Brodmann area 4 of the lesioned hemisphere (P<0.05). The stroke size and location were not associated with GFA differences. Differences between the GFA of the lesioned and non-lesioned hemispheres varied depending on the affected brain region, age at onset of paralysis, and paralysis of the dominant or non-dominant hand. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. On gauged Baryon and Lepton numbers

    International Nuclear Information System (INIS)

    Rajpoot, S.

    1990-01-01

    The observation that Baryon number and Lepton number are conserved in nature provides strong motivation for associating gauge symmetries to these conserved numbers. This endeavor requires that the gauge group of electroweak interactions be extended from SU(2) L X U(1) Y to SU(2) L X U(1) R X U(1) Lepton where U(1) R couples only to the right-handed quarks and leptons. If it furthur postulated that right-handed currents exist on par with the left-handed ones, then the full electroweak symmetry is SU(2) L X SU(2) R X U(1) Baryon X U(1) Lepton . The SU(2) L X SU(2) R X U(1) Baryon X U(1) Lepton model is described in some detail. The triangle anomalies of the three families of quarks and leptons in the model are cancelled invoking leptoquark matter which is new fermionic matter that carries baryon as well as lepton numbers. In addition to the standard neutral boson (Z degree), the theory predicts two neutral gauge bosons with mass lower bounds of 120 GeV and 210 GeV which makes these particles prospective candidates for production at LEP, the TEVATRON and the SSC

  2. Diffusion tensor imaging tensor shape analysis for assessment of regional white matter differences.

    Science.gov (United States)

    Middleton, Dana M; Li, Jonathan Y; Lee, Hui J; Chen, Steven; Dickson, Patricia I; Ellinwood, N Matthew; White, Leonard E; Provenzale, James M

    2017-08-01

    Purpose The purpose of this study was to investigate a novel tensor shape plot analysis technique of diffusion tensor imaging data as a means to assess microstructural differences in brain tissue. We hypothesized that this technique could distinguish white matter regions with different microstructural compositions. Methods Three normal canines were euthanized at seven weeks old. Their brains were imaged using identical diffusion tensor imaging protocols on a 7T small-animal magnetic resonance imaging system. We examined two white matter regions, the internal capsule and the centrum semiovale, each subdivided into an anterior and posterior region. We placed 100 regions of interest in each of the four brain regions. Eigenvalues for each region of interest triangulated onto tensor shape plots as the weighted average of three shape metrics at the plot's vertices: CS, CL, and CP. Results The distribution of data on the plots for the internal capsule differed markedly from the centrum semiovale data, thus confirming our hypothesis. Furthermore, data for the internal capsule were distributed in a relatively tight cluster, possibly reflecting the compact and parallel nature of its fibers, while data for the centrum semiovale were more widely distributed, consistent with the less compact and often crossing pattern of its fibers. This indicates that the tensor shape plot technique can depict data in similar regions as being alike. Conclusion Tensor shape plots successfully depicted differences in tissue microstructure and reflected the microstructure of individual brain regions. This proof of principle study suggests that if our findings are reproduced in larger samples, including abnormal white matter states, the technique may be useful in assessment of white matter diseases.

  3. Interacting diffusive unified dark energy and dark matter from scalar fields

    Energy Technology Data Exchange (ETDEWEB)

    Benisty, David; Guendelman, E.I. [Ben Gurion University of the Negev, Department of Physics, Beersheba (Israel)

    2017-06-15

    Here we generalize ideas of unified dark matter-dark energy in the context of two measure theories and of dynamical space time theories. In two measure theories one uses metric independent volume elements and this allows one to construct unified dark matter-dark energy, where the cosmological constant appears as an integration constant associated with the equation of motion of the measure fields. The dynamical space-time theories generalize the two measure theories by introducing a vector field whose equation of motion guarantees the conservation of a certain Energy Momentum tensor, which may be related, but in general is not the same as the gravitational Energy Momentum tensor. We propose two formulations of this idea: (I) by demanding that this vector field be the gradient of a scalar, (II) by considering the dynamical space field appearing in another part of the action. Then the dynamical space time theory becomes a theory of Diffusive Unified dark energy and dark matter. These generalizations produce non-conserved energy momentum tensors instead of conserved energy momentum tensors which leads at the end to a formulation of interacting DE-DM dust models in the form of a diffusive type interacting Unified dark energy and dark matter scenario. We solved analytically the theories for perturbative solution and asymptotic solution, and we show that the ΛCDM is a fixed point of these theories at large times. Also a preliminary argument as regards the good behavior of the theory at the quantum level is proposed for both theories. (orig.)

  4. Density-dependent effective baryon–baryon interaction from chiral three-baryon forces

    Energy Technology Data Exchange (ETDEWEB)

    Petschauer, Stefan, E-mail: stefan.petschauer@ph.tum.de [Physik Department, Technische Universität München, D-85747 Garching (Germany); Haidenbauer, Johann [Institute for Advanced Simulation, Institut für Kernphysik and Jülich Center for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich (Germany); Kaiser, Norbert [Physik Department, Technische Universität München, D-85747 Garching (Germany); Meißner, Ulf-G. [Institute for Advanced Simulation, Institut für Kernphysik and Jülich Center for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich (Germany); Helmholtz-Institut für Strahlen- und Kernphysik, Universität Bonn, D-53115 Bonn (Germany); Bethe Center for Theoretical Physics, Universität Bonn, D-53115 Bonn (Germany); Weise, Wolfram [Physik Department, Technische Universität München, D-85747 Garching (Germany)

    2017-01-15

    A density-dependent effective potential for the baryon–baryon interaction in the presence of the (hyper)nuclear medium is constructed, based on the leading (irreducible) three-baryon forces derived within SU(3) chiral effective field theory. We evaluate the contributions from three classes: contact terms, one-pion exchange and two-pion exchange. In the strangeness-zero sector we recover the known result for the in-medium nucleon–nucleon interaction. Explicit expressions for the ΛN in-medium potential in (asymmetric) nuclear matter are presented. Our results are suitable for implementation into calculations of (hyper)nuclear matter. In order to estimate the low-energy constants of the leading three-baryon forces we introduce the decuplet baryons as explicit degrees of freedom and construct the relevant terms in the minimal non-relativistic Lagrangian. With these, the constants are estimated through decuplet saturation. Utilizing this approximation we provide numerical results for the effect of the three-body force in symmetric nuclear matter and pure neutron matter on the ΛN interaction. A moderate repulsion that increases with density is found in comparison to the free ΛN interaction.

  5. Permeability-diffusivity modeling vs. fractional anisotropy on white matter integrity assessment and application in schizophrenia.

    Science.gov (United States)

    Kochunov, P; Chiappelli, J; Hong, L E

    2013-01-01

    Diffusion tensor imaging (DTI) assumes a single pool of anisotropically diffusing water to calculate fractional anisotropy (FA) and is commonly used to ascertain white matter (WM) deficits in schizophrenia. At higher b-values, diffusion-signal decay becomes bi-exponential, suggesting the presence of two, unrestricted and restricted, water pools. Theoretical work suggests that semi-permeable cellular membrane rather than the presence of two physical compartments is the cause. The permeability-diffusivity (PD) parameters measured from bi-exponential modeling may offer advantages, over traditional DTI-FA, in identifying WM deficits in schizophrenia. Imaging was performed in N = 26/26 patients/controls (age = 20-61 years, average age = 40.5 ± 12.6). Imaging consisted of fifteen b-shells: b = 250-3800 s/mm(2) with 30 directions/shell, covering seven slices of mid-sagittal corpus callosum (CC) at 1.7 × 1.7 × 4.6 mm. 64-direction DTI was also collected. Permeability-diffusivity-index (PDI), the ratio of restricted to unrestricted apparent diffusion coefficients, and the fraction of unrestricted compartment (Mu) were calculated for CC and cingulate gray matter (GM). FA values for CC were calculated using tract-based-spatial-statistics. Patients had significantly reduced PDI in CC (p ≅ 10(- 4)) and cingulate GM (p = 0.002), while differences in CC FA were modest (p ≅ .03). There was no group-related difference in Mu. Additional theoretical-modeling analysis suggested that reduced PDI in patients may be caused by reduced cross-membrane water molecule exchanges. PDI measurements for cerebral WM and GM yielded more robust patient-control differences than DTI-FA. Theoretical work offers an explanation that patient-control PDI differences should implicate abnormal active membrane permeability. This would implicate abnormal activities in ion-channels that use water as substrate for ion exchange, in cerebral tissues of schizophrenia patients.

  6. Strong coupling QCD at finite baryon-number density

    International Nuclear Information System (INIS)

    Karsch, F.; Muetter, K.H.

    1989-01-01

    We present a new representation of the partition function for strong-coupling QCD which is suitable also for finite baryon-number-density simulations. This enables us to study the phase structure in the canonical formulation (with fixed baryon number B) as well as the grand canonical one (with fixed chemical potential μ). We find a clear signal for a first-order chiral phase transition at μ c a=0.63. The critical baryon-number density n c a 3 =0.045 is only slightly higher than the density of nuclear matter. (orig.)

  7. Subcortical White Matter Changes with Normal Aging Detected by Multi-Shot High Resolution Diffusion Tensor Imaging.

    Directory of Open Access Journals (Sweden)

    Sheng Xie

    Full Text Available Subcortical white matter builds neural connections between cortical and subcortical regions and constitutes the basis of neural networks. It plays a very important role in normal brain function. Various studies have shown that white matter deteriorates with aging. However, due to the limited spatial resolution provided by traditional diffusion imaging techniques, microstructural information from subcortical white matter with normal aging has not been comprehensively assessed. This study aims to investigate the deterioration effect with aging in the subcortical white matter and provide a baseline standard for pathological disorder diagnosis. We apply our newly developed multi-shot high resolution diffusion tensor imaging, using self-feeding multiplexed sensitivity-encoding, to measure subcortical white matter changes in regions of interest of healthy persons with a wide age range. Results show significant fractional anisotropy decline and radial diffusivity increasing with age, especially in the anterior part of the brain. We also find that subcortical white matter has more prominent changes than white matter close to the central brain. The observed changes in the subcortical white matter may be indicative of a mild demyelination and a loss of myelinated axons, which may contribute to normal age-related functional decline.

  8. White Matter Structural Differences in Young Children With Type 1 Diabetes: A Diffusion Tensor Imaging Study

    Science.gov (United States)

    Aye, Tandy; Barnea-Goraly, Naama; Ambler, Christian; Hoang, Sherry; Schleifer, Kristin; Park, Yaena; Drobny, Jessica; Wilson, Darrell M.; Reiss, Allan L.; Buckingham, Bruce A.

    2012-01-01

    OBJECTIVE To detect clinical correlates of cognitive abilities and white matter (WM) microstructural changes using diffusion tensor imaging (DTI) in young children with type 1 diabetes. RESEARCH DESIGN AND METHODS Children, ages 3 to <10 years, with type 1 diabetes (n = 22) and age- and sex-matched healthy control subjects (n = 14) completed neurocognitive testing and DTI scans. RESULTS Compared with healthy controls, children with type 1 diabetes had lower axial diffusivity (AD) values (P = 0.046) in the temporal and parietal lobe regions. There were no significant differences between groups in fractional anisotropy and radial diffusivity (RD). Within the diabetes group, there was a significant, positive correlation between time-weighted HbA1c and RD (P = 0.028). A higher, time-weighted HbA1c value was significantly correlated with lower overall intellectual functioning measured by the full-scale intelligence quotient (P = 0.03). CONCLUSIONS Children with type 1 diabetes had significantly different WM structure (as measured by AD) when compared with controls. In addition, WM structural differences (as measured by RD) were significantly correlated with their HbA1c values. Additional studies are needed to determine if WM microstructural differences in young children with type 1 diabetes predict future neurocognitive outcome. PMID:22966090

  9. Changes in Parahippocampal White Matter Integrity in Amnestic Mild Cognitive Impairment: A Diffusion Tensor Imaging Study

    Directory of Open Access Journals (Sweden)

    E. J. Rogalski

    2009-01-01

    Full Text Available In the present study, changes in the parahippocampal white matter (PWM, in the region that includes the perforant path, were investigated, in vivo, in 14 individuals with amnestic mild cognitive impairment (aMCI compared to 14 elderly controls with no cognitive impairment (NCI. For this purpose, (1 volumetry; (2 diffusion tensor imaging (DTI derived measures of mean diffusivity (MD and fractional anisotropy (FA; and (3 tractography were used. In addition, regression models were utilized to examine the association of PWM measurements with memory decline. The results from this study confirm previous findings in our laboratory and others, showing that compared to controls, individuals with aMCI have PWM volume loss. In addition to volume reduction, participants with aMCI demonstrated a significant increase in MD, but no difference in FA, both in the PWM region and in fibers modeled to pass through the PWM region. Further, the DTI metric of MD was associated with declarative memory performance, suggesting it may be a sensitive marker for memory dysfunction. These results indicate that there is general tissue loss and degradation (decreased volume; increased MD in individuals with aMCI compared to older people with normal cognitive function. However, the microstructural organization of remaining fibers, as determined by measures of anisotropic diffusion, is not significantly different from that of controls.

  10. Diffusion

    International Nuclear Information System (INIS)

    Kubaschewski, O.

    1983-01-01

    The diffusion rate values of titanium, its compounds and alloys are summarized and tabulated. The individual chemical diffusion coefficients and self-diffusion coefficients of certain isotopes are given. Experimental methods are listed which were used for the determination of diffusion coefficients. Some values have been taken over from other studies. Also given are graphs showing the temperature dependences of diffusion and changes in the diffusion coefficient with concentration changes

  11. Surface-based reconstruction and diffusion MRI in the assessment of gray and white matter damage in multiple sclerosis

    Science.gov (United States)

    Caffini, Matteo; Bergsland, Niels; LaganÃ, Marcella; Tavazzi, Eleonora; Tortorella, Paola; Rovaris, Marco; Baselli, Giuseppe

    2014-03-01

    Despite advances in the application of nonconventional MRI techniques in furthering the understanding of multiple sclerosis pathogenic mechanisms, there are still many unanswered questions, such as the relationship between gray and white matter damage. We applied a combination of advanced surface-based reconstruction and diffusion tensor imaging techniques to address this issue. We found significant relationships between white matter tract integrity indices and corresponding cortical structures. Our results suggest a direct link between damage in white and gray matter and contribute to the notion of gray matter loss relating to clinical disability.

  12. Massive black holes and light-element nucleosynthesis in a baryonic universe

    Science.gov (United States)

    Gnedin, Nickolay Y.; Ostriker, Jeremiah P.; Rees, Martin J.

    1995-01-01

    We reexamine the model proposed by Gnedin & Ostriker (1992) in which Jeans mass black holes (M(sub BH) approximately = 10(exp 6) solar mass) form shortly after decoupling. There is no nonbaryonic dark matter in this model, but we examine the possibility that Omega(sub b) is considerably larger than given by normal nucleosynthesis. Here we allow for the fact that much of the high baryon-to-photon ratio material will collapse leaving the universe of remaining material with light-element abundances more in accord with the residual baryonic density (approximately = 10(exp -2)) than with Omega(sub 0) and the initial baryonic density (approximately = 10(exp -1)). We find that no reasonable model can be made with random-phase density fluctuations, if the power on scales smaller than 10(exp 6) solar mass is as large as expected. However, phase-correlated models of the type that might occur in connection with topological singularities can be made with Omega(sub b) h(exp 2) = 0.013 +/- 0.001, 0.15 approximately less than Omega(sub 0) approximately less than 0.4, which are either flat (Omega(sub lambda) = 1 - Omega(sub 0)) or open (Omega(sub lambda) = 0) and which satisfy all the observational constraints which we apply, including the large baryon-to-total mass ratio found in the X-ray clusters. The remnant baryon density is thus close to that obtained in the standard picture (Omega(sub b) h(exp 2) = 0.0125 +/- 0.0025; Walker et al. 1991). The spectral index implied for fluctuations in the baryonic isocurvature scenario, -1 less than m less than 0, is in the range expected by other arguments based on large-scale structure and microwave fluctuation constraints. The dark matter in this picture is in the form of massive black holes. Accretion onto them at early epochs releases high-energy photons which significantly heat and reionize the universe. But photodissociation does not materially change light-element abundances. A typical model gives bar-y approximately = 1 x 10(exp -5

  13. White matter microstructure and cognitive decline in metabolic syndrome: a review of diffusion tensor imaging.

    Science.gov (United States)

    Alfaro, Freddy J; Gavrieli, Anna; Saade-Lemus, Patricia; Lioutas, Vasileios-Arsenios; Upadhyay, Jagriti; Novak, Vera

    2018-01-01

    Metabolic syndrome is a cluster of cardiovascular risk factors defined by the presence of abdominal obesity, glucose intolerance, hypertension and/or dyslipidemia. It is a major public health epidemic worldwide, and a known risk factor for the development of cognitive dysfunction and dementia. Several studies have demonstrated a positive association between the presence of metabolic syndrome and worse cognitive outcomes, however, evidence of brain structure pathology is limited. Diffusion tensor imaging has offered new opportunities to detect microstructural white matter changes in metabolic syndrome, and a possibility to detect associations between functional and structural abnormalities. This review analyzes the impact of metabolic syndrome on white matter microstructural integrity, brain structure abnormalities and their relationship to cognitive function. Each of the metabolic syndrome components exerts a specific signature of white matter microstructural abnormalities. Metabolic syndrome and its components exert both additive/synergistic, as well as, independent effects on brain microstructure thus accelerating brain aging and cognitive decline. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Diffusion tensor imaging of brain white matter in Huntington gene mutation individuals

    Directory of Open Access Journals (Sweden)

    Roberta Arb Saba

    Full Text Available ABSTRACT Objective To evaluate the role of the involvement of white matter tracts in huntingtin gene mutation patients as a potential biomarker of the progression of the disease. Methods We evaluated 34 participants (11 symptomatic huntingtin gene mutation, 12 presymptomatic huntingtin gene mutation, and 11 controls. We performed brain magnetic resonance imaging to assess white matter integrity using diffusion tensor imaging, with measurement of fractional anisotropy. Results We observed a significant decrease of fractional anisotropy in the cortical spinal tracts, corona radiate, corpus callosum, external capsule, thalamic radiations, superior and inferior longitudinal fasciculus, and inferior frontal-occipital fasciculus in the Huntington disease group compared to the control and presymptomatic groups. Reduction of fractional anisotropy is indicative of a degenerative process and axonal loss. There was no statistically significant difference between the presymptomatic and control groups. Conclusion White matter integrity is affected in huntingtin gene mutation symptomatic individuals, but other studies with larger samples are required to assess its usefulness in the progression of the neurodegenerative process.

  15. Photoproduction of hermaphrodite baryons

    International Nuclear Information System (INIS)

    Barnes, T.; Close, F.E.

    1983-02-01

    It is shown that photoexcitation of the lightest hermaphrodite baryons is strongly suppressed from proton targets but allowed from neutrons, a result that is reminiscent of a quark model selection rule due to Moorhouse (Phys. Rev. Lett.; 16:772 (1966)). This is consistent with suggestions that the P 11 (1710) is the lightest q 3 G baryon and eliminates the possibility that the Roper resonance is dominantly an hermaphrodite state. Magnetic moments do not constrain the possibility of considerable mixing of q 3 G into the nucleon and delta's Fock space wavefunctions. (author)

  16. A radiological study of cerebral white matter lesions in patients with dementia using diffusion-weighted MR imaging

    International Nuclear Information System (INIS)

    Shindo, Hiroaki; Hanyu, Haruo; Kakizaki, Dai; Abe, Kimihiko; Takasaki, Masaru

    1999-01-01

    We investigated the changes in water diffusion in the cerebral white matter and the corpus callosum in 12 patients with Binswanger's disease (BD), and 19 patients with Alzheimer's Disease (AD), including 12 without (AD-) and 7 with periventricular hyperintensity (PVH) lesions (AD+), using diffusion-weighted magnetic resonance imaging (MRI). Apparent diffusion coefficients (ADCs) in the anterior and posterior white matter were significantly higher in patients with BD and AD than in 12 age-matched controls. The ADCs were significantly higher in AD (+) than in AD (-) patients. Anisotropic ratios (ARs), defined as diffusion restricted perpendicular to the direction of the nerve fibers, were significantly higher in BD and AD (+) patients, and even in AD (-) patients, than in the controls. ARs in the anterior white matter were significantly higher in BD than in AD (+), while in the posterior white matter the ratios were significantly higher in AD (+) rather than BD patients. The ADCs and ARs in the genu of the corpus callosum were significantly higher in patients with BD and AD (+) compared to the control subjects, while ADCs and ARs in the splenium were significantly higher in patients with AD (+) and AD (-) than in those with BD. These results suggest that mild myelin loss occurs in AD patients even in apparently normal white matter and in the splenium of the corpus callosum. A definite loss of myelin and axons, including incomplete infarction, occurs preferentially in anterior white matter in BD, while in posterior white matter in AD (+), as seen on T2-weighted images as PVH. Studies with diffusion-weighted MRI may allow the characterization of different pathological processes and enable the demonstration of underlying white matter lesion in patients with dementia that cannot be visualized by conventional MRI. (author)

  17. Diffusive and quantum effects of water properties in different states of matter

    International Nuclear Information System (INIS)

    Yeh, Kuan-Yu; Huang, Shao-Nung; Chen, Li-Jen; Lin, Shiang-Tai

    2014-01-01

    The enthalpy, entropy, and free energy of water are important physical quantities for understanding many interesting phenomena in biological systems. However, conventional approaches require different treatments to incorporate quantum and diffusive effects of water in different states of matter. In this work, we demonstrate the use of the two-phase thermodynamic (2PT) model as a unified approach to obtain the properties of water over the whole phase region of water from short (∼20 ps) classical molecular dynamics trajectories. The 2PT model provides an effective way to separate the diffusive modes (gas-like component) from the harmonic vibrational modes (solid-like component) in the vibrational density of states (DoS). Therefore, both diffusive and quantum effect can be properly accounted for water by applying suitable statistical mechanical weighting functions to the DoS components. We applied the 2PT model to systematically examine the enthalpy, entropy, and their temperature dependence of five commonly used rigid water models. The 2PT results are found to be consistent with those obtained from more sophisticated calculations. While the thermodynamic properties determined from different water models are largely similar, the phase boundary determined from the equality of free energy is very sensitive to the small inaccuracy in the values of enthalpy and absolute entropy. The enthalpy, entropy, and diffusivity of water are strongly interrelated, which challenge further improvement of rigid water model via parameter fitting. Our results show that the 2PT is an efficient method for studying the properties of water under various chemical and biological environments

  18. Connectivity-enhanced diffusion analysis reveals white matter density disruptions in first episode and chronic schizophrenia

    Directory of Open Access Journals (Sweden)

    Rachael G. Grazioplene

    microstructural group differences. These results underline the need to move beyond tensor-based models in favor of acquisition and analysis techniques that can help disambiguate different sources of white matter disruptions associated with schizophrenia. Keywords: Schizophrenia, Diffusion imaging, DWI, DTI, First episode, Chronic, White matter, Fiber density, Fiber organization

  19. Cortical grey matter and subcortical white matter brain microstructural changes in schizophrenia are localised and age independent: a case-control diffusion tensor imaging study.

    Science.gov (United States)

    Chiapponi, Chiara; Piras, Fabrizio; Piras, Federica; Fagioli, Sabrina; Caltagirone, Carlo; Spalletta, Gianfranco

    2013-01-01

    It is still unknown whether the structural brain impairments that characterize schizophrenia (SZ) worsen during the lifetime. Here, we aimed to describe age-related microstructural brain changes in cortical grey matter and subcortical white matter of patients affected by SZ. In this diffusion tensor imaging study, we included 69 patients diagnosed with SZ and 69 healthy control (HC) subjects, age and gender matched. We carried out analyses of covariance, with diagnosis as fixed factor and brain diffusion-related parameters as dependent variables, and controlled for the effect of education. White matter fractional anisotropy decreased in the entire age range spanned (18-65 years) in both SZ and HC and was significantly lower in younger patients with SZ, with no interaction (age by diagnosis) effect in fiber tracts including corpus callosum, corona radiata, thalamic radiations and external capsule. Also, grey matter mean diffusivity increased in the entire age range in both SZ and HC and was significantly higher in younger patients, with no age by diagnosis interaction in the left frontal operculum cortex, left insula and left planum polare and in the right temporal pole and right intracalcarine cortex. In individuals with SZ we found that localized brain cortical and white matter subcortical microstructural impairments appear early in life but do not worsen in the 18-65 year age range.

  20. Cortical grey matter and subcortical white matter brain microstructural changes in schizophrenia are localised and age independent: a case-control diffusion tensor imaging study.

    Directory of Open Access Journals (Sweden)

    Chiara Chiapponi

    Full Text Available It is still unknown whether the structural brain impairments that characterize schizophrenia (SZ worsen during the lifetime. Here, we aimed to describe age-related microstructural brain changes in cortical grey matter and subcortical white matter of patients affected by SZ. In this diffusion tensor imaging study, we included 69 patients diagnosed with SZ and 69 healthy control (HC subjects, age and gender matched. We carried out analyses of covariance, with diagnosis as fixed factor and brain diffusion-related parameters as dependent variables, and controlled for the effect of education. White matter fractional anisotropy decreased in the entire age range spanned (18-65 years in both SZ and HC and was significantly lower in younger patients with SZ, with no interaction (age by diagnosis effect in fiber tracts including corpus callosum, corona radiata, thalamic radiations and external capsule. Also, grey matter mean diffusivity increased in the entire age range in both SZ and HC and was significantly higher in younger patients, with no age by diagnosis interaction in the left frontal operculum cortex, left insula and left planum polare and in the right temporal pole and right intracalcarine cortex. In individuals with SZ we found that localized brain cortical and white matter subcortical microstructural impairments appear early in life but do not worsen in the 18-65 year age range.

  1. Baryons and ladders

    International Nuclear Information System (INIS)

    Ball, R.D.

    1990-01-01

    By formal manipulation of the QCD functional integral we arrive at a relativistic low energy effective theory of non-local color singlet mesons and baryons, which at tree level sums up ladders of effective glue exchange between constituent quarks. (orig.)

  2. Baryons on the lattice

    International Nuclear Information System (INIS)

    Bali, G.S.

    2005-01-01

    I comment on progress of lattice QCD techniques and calculations. Recent results on pentaquark masses as well as of the spectrum of excited baryons are summarized and interpreted. The present state of calculations of quantities related to the nucleon structure and of electromagnetic transition form factors is surveyed

  3. Baryon resonances in nuclei

    International Nuclear Information System (INIS)

    Arenhoevel, H.

    1977-01-01

    The field of baryon resonances in nuclei is reviewed. Theoretical developments and experimental evidence as well are discussed. Special emphasis is laid on electromagnetic processes for the two nucleon system. Some aspects of real isobars in nuclei are touched upon. (orig.) [de

  4. Diquarks in rotating baryons

    International Nuclear Information System (INIS)

    Martin, A.

    1989-01-01

    This paper shows that the minimum energy three-quark classical configuration for a given angular momentum and linear two-body potentials between the quarks is a quark-diquark system. The authors deduce from this that baryons at large angular momentum have a quark-diquark structure. Explicit calculations by Flack, Richard and Silvestre-Brac show this effect

  5. Problems in baryon spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Capstick, S. [Florida State Univ., Tallahassee, FL (United States)

    1994-04-01

    Current issues and problems in the physics of ground- and excited-state baryons are considered, and are classified into those which should be resolved by CEBAF in its present form, and those which may require CEBAF to undergo an energy upgrade to 8 GeV or more. Recent theoretical developments designed to address these problems are outlined.

  6. Baryons and QCD

    International Nuclear Information System (INIS)

    Nathan Isgur

    1997-01-01

    The author presents an idiosyncratic view of baryons which calls for a marriage between quark-based and hadronic models of QCD. He advocates a treatment based on valence quark plus glue dominance of hadron structure, with the sea of q pairs (in the form of virtual hadron pairs) as important corrections

  7. Conservative constraints on dark matter from the Fermi-LAT isotropic diffuse gamma-ray background spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Abazajian, Kevork N.; Agrawal, Prateek; Chacko, Zackaria [Maryland Center for Fundamental Physics, Department of Physics, University of Maryland, College Park, Maryland 20742 (United States); Kilic, Can, E-mail: kev@umd.edu, E-mail: apr@umd.edu, E-mail: zchacko@umd.edu, E-mail: kilic@physics.rutgers.edu [Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854 (United States)

    2010-11-01

    We examine the constraints on final state radiation from Weakly Interacting Massive Particle (WIMP) dark matter candidates annihilating into various standard model final states, as imposed by the measurement of the isotropic diffuse gamma-ray background by the Large Area Telescope aboard the Fermi Gamma-Ray Space Telescope. The expected isotropic diffuse signal from dark matter annihilation has contributions from the local Milky Way (MW) as well as from extragalactic dark matter. The signal from the MW is very insensitive to the adopted dark matter profile of the halos, and dominates the signal from extragalactic halos, which is sensitive to the low mass cut-off of the halo mass function. We adopt a conservative model for both the low halo mass survival cut-off and the substructure boost factor of the Galactic and extragalactic components, and only consider the primary final state radiation. This provides robust constraints which reach the thermal production cross-section for low mass WIMPs annihilating into hadronic modes. We also reanalyze limits from HESS observations of the Galactic Ridge region using a conservative model for the dark matter halo profile. When combined with the HESS constraint, the isotropic diffuse spectrum rules out all interpretations of the PAMELA positron excess based on dark matter annihilation into two lepton final states. Annihilation into four leptons through new intermediate states, although constrained by the data, is not excluded.

  8. Conservative constraints on dark matter from the Fermi-LAT isotropic diffuse gamma-ray background spectrum

    International Nuclear Information System (INIS)

    Abazajian, Kevork N.; Agrawal, Prateek; Chacko, Zackaria; Kilic, Can

    2010-01-01

    We examine the constraints on final state radiation from Weakly Interacting Massive Particle (WIMP) dark matter candidates annihilating into various standard model final states, as imposed by the measurement of the isotropic diffuse gamma-ray background by the Large Area Telescope aboard the Fermi Gamma-Ray Space Telescope. The expected isotropic diffuse signal from dark matter annihilation has contributions from the local Milky Way (MW) as well as from extragalactic dark matter. The signal from the MW is very insensitive to the adopted dark matter profile of the halos, and dominates the signal from extragalactic halos, which is sensitive to the low mass cut-off of the halo mass function. We adopt a conservative model for both the low halo mass survival cut-off and the substructure boost factor of the Galactic and extragalactic components, and only consider the primary final state radiation. This provides robust constraints which reach the thermal production cross-section for low mass WIMPs annihilating into hadronic modes. We also reanalyze limits from HESS observations of the Galactic Ridge region using a conservative model for the dark matter halo profile. When combined with the HESS constraint, the isotropic diffuse spectrum rules out all interpretations of the PAMELA positron excess based on dark matter annihilation into two lepton final states. Annihilation into four leptons through new intermediate states, although constrained by the data, is not excluded

  9. A review of anisotropic conductivity models of brain white matter based on diffusion tensor imaging.

    Science.gov (United States)

    Wu, Zhanxiong; Liu, Yang; Hong, Ming; Yu, Xiaohui

    2018-06-01

    The conductivity of brain tissues is not only essential for electromagnetic source estimation (ESI), but also a key reflector of the brain functional changes. Different from the other brain tissues, the conductivity of whiter matter (WM) is highly anisotropic and a tensor is needed to describe it. The traditional electrical property imaging methods, such as electrical impedance tomography (EIT) and magnetic resonance electrical impedance tomography (MREIT), usually fail to image the anisotropic conductivity tensor of WM with high spatial resolution. The diffusion tensor imaging (DTI) is a newly developed technique that can fulfill this purpose. This paper reviews the existing anisotropic conductivity models of WM based on the DTI and discusses their advantages and disadvantages, as well as identifies opportunities for future research on this subject. It is crucial to obtain the linear conversion coefficient between the eigenvalues of anisotropic conductivity tensor and diffusion tensor, since they share the same eigenvectors. We conclude that the electrochemical model is suitable for ESI analysis because the conversion coefficient can be directly obtained from the concentration of ions in extracellular liquid and that the volume fraction model is appropriate to study the influence of WM structural changes on electrical conductivity. Graphical abstract ᅟ.

  10. Effect of the Maximum Dose on White Matter Fiber Bundles Using Longitudinal Diffusion Tensor Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Tong; Chapman, Christopher H. [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Tsien, Christina [Department of Radiation Oncology, Washington University at St Louis, St Louis, Missouri (United States); Kim, Michelle; Spratt, Daniel E.; Lawrence, Theodore S. [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Cao, Yue, E-mail: yuecao@umich.edu [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Department of Radiology, University of Michigan, Ann Arbor, Michigan (United States); Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan (United States)

    2016-11-01

    Purpose: Previous efforts to decrease neurocognitive effects of radiation focused on sparing isolated cortical structures. We hypothesize that understanding temporal, spatial, and dosimetric patterns of radiation damage to whole-brain white matter (WM) after partial-brain irradiation might also be important. Therefore, we carried out a study to develop the methodology to assess radiation therapy (RT)–induced damage to whole-brain WM bundles. Methods and Materials: An atlas-based, automated WM tractography analysis was implemented to quantify longitudinal changes in indices of diffusion tensor imaging (DTI) of 22 major WM fibers in 33 patients with predominantly low-grade or benign brain tumors treated by RT. Six DTI scans per patient were performed from before RT to 18 months after RT. The DTI indices and planned doses (maximum and mean doses) were mapped onto profiles of each of 22 WM bundles. A multivariate linear regression was performed to determine the main dose effect as well as the influence of other clinical factors on longitudinal percentage changes in axial diffusivity (AD) and radial diffusivity (RD) from before RT. Results: Among 22 fiber bundles, AD or RD changes in 12 bundles were affected significantly by doses (P<.05), as the effect was progressive over time. In 9 elongated tracts, decreased AD or RD was significantly related to maximum doses received, consistent with a serial structure. In individual bundles, AD changes were up to 11.5% at the maximum dose locations 18 months after RT. The dose effect on WM was greater in older female patients than younger male patients. Conclusions: Our study demonstrates for the first time that the maximum dose to the elongated WM bundles causes post-RT damage in WM. Validation and correlative studies are necessary to determine the ability and impact of sparing these bundles on preserving neurocognitive function after RT.

  11. Diffuse periventricular leukomalacia in preterm children: assessment of grey matter changes by MRI

    International Nuclear Information System (INIS)

    Tzarouchi, L.C.; Xydis, V.; Zikou, A.K.; Papastefanaki, M.; Argyropoulou, Maria I.; Drougia, A.; Andronikou, S.; Astrakas, L.G.

    2011-01-01

    Preterm children may have cognitive deficits and behavioural disorders suggestive of grey matter (GM) injury. The prevalence is higher in preterm children with diffuse periventricular leukomalacia (dPVL). Evaluate changes in the volume of 116 GM areas in preterm children with dPVL. Eleven preterm children with dPVL, gestational age 32.8 ± 2.6 weeks, examined at corrected age 22.0 ± 18.2 months and 33 matched preterm controls with normal brain MRI were studied. Volumes of 116 individual GM areas, and white matter/cerebrospinal fluid (WM/CSF) ratio were calculated on T1-weighted high-resolution images after segmentation. Relative to controls, children with dPVL had decreased GM volume of the hippocampus, amygdala, and frontal lobes and temporal middle gyrus (P < 0.05); increased GM volume of the putamen, thalamus, globus pallidum, superior temporal gyrus and of the parietal and occipital lobes (P < 0.05) and lower WM volume/higher CSF volume (P < 0.05). WM/CSF ratios also differed (P < 0.05). Preterm children with dPVL have increased regional GM volume in some areas probably related with a process of brain plasticity-regeneration and reduced GM volume in areas associated with cognition and memory. (orig.)

  12. Diffuse periventricular leukomalacia in preterm children: assessment of grey matter changes by MRI

    Energy Technology Data Exchange (ETDEWEB)

    Tzarouchi, L.C.; Xydis, V.; Zikou, A.K.; Papastefanaki, M.; Argyropoulou, Maria I. [University of Ioannina, Department of Radiology, Medical School, Ioannina (Greece); Drougia, A.; Andronikou, S. [University of Ioannina, Neonatal Intensive Care Unit, Child Health Department, Medical School, Ioannina (Greece); Astrakas, L.G. [University of Ioannina, Department of Medical Physics, Medical School, Ioannina (Greece)

    2011-12-15

    Preterm children may have cognitive deficits and behavioural disorders suggestive of grey matter (GM) injury. The prevalence is higher in preterm children with diffuse periventricular leukomalacia (dPVL). Evaluate changes in the volume of 116 GM areas in preterm children with dPVL. Eleven preterm children with dPVL, gestational age 32.8 {+-} 2.6 weeks, examined at corrected age 22.0 {+-} 18.2 months and 33 matched preterm controls with normal brain MRI were studied. Volumes of 116 individual GM areas, and white matter/cerebrospinal fluid (WM/CSF) ratio were calculated on T1-weighted high-resolution images after segmentation. Relative to controls, children with dPVL had decreased GM volume of the hippocampus, amygdala, and frontal lobes and temporal middle gyrus (P < 0.05); increased GM volume of the putamen, thalamus, globus pallidum, superior temporal gyrus and of the parietal and occipital lobes (P < 0.05) and lower WM volume/higher CSF volume (P < 0.05). WM/CSF ratios also differed (P < 0.05). Preterm children with dPVL have increased regional GM volume in some areas probably related with a process of brain plasticity-regeneration and reduced GM volume in areas associated with cognition and memory. (orig.)

  13. Soft matter in hard confinement: phase transition thermodynamics, structure, texture, diffusion and flow in nanoporous media

    Science.gov (United States)

    Huber, Patrick

    2015-03-01

    Spatial confinement in nanoporous media affects the structure, thermodynamics and mobility of molecular soft matter often markedly. This article reviews thermodynamic equilibrium phenomena, such as physisorption, capillary condensation, crystallisation, self-diffusion, and structural phase transitions as well as selected aspects of the emerging field of spatially confined, non-equilibrium physics, i.e. the rheology of liquids, capillarity-driven flow phenomena, and imbibition front broadening in nanoporous materials. The observations in the nanoscale systems are related to the corresponding bulk phenomenologies. The complexity of the confined molecular species is varied from simple building blocks, like noble gas atoms, normal alkanes and alcohols to liquid crystals, polymers, ionic liquids, proteins and water. Mostly, experiments with mesoporous solids of alumina, gold, carbon, silica, and silicon with pore diameters ranging from a few up to 50 nm are presented. The observed peculiarities of nanopore-confined condensed matter are also discussed with regard to applications. A particular emphasis is put on texture formation upon crystallisation in nanoporous media, a topic both of high fundamental interest and of increasing nanotechnological importance, e.g. for the synthesis of organic/inorganic hybrid materials by melt infiltration, the usage of nanoporous solids in crystal nucleation or in template-assisted electrochemical deposition of nano structures.

  14. Neutrino diffusion in the pasta phase matter within the Thomas-Fermi approach

    Energy Technology Data Exchange (ETDEWEB)

    Furtado, U.J.; Avancini, S.S. [Universidade Federal de Santa Catarina, Departamento de Fisica, CFM, CP. 476, Florianopolis - SC (Brazil); University of Coimbra, CFisUC, Department of Physics, Coimbra (Portugal); Marinelli, J.R.; Martarello, W. [Universidade Federal de Santa Catarina, Departamento de Fisica, CFM, CP. 476, Florianopolis - SC (Brazil); Providencia, C. [University of Coimbra, CFisUC, Department of Physics, Coimbra (Portugal)

    2016-09-15

    The behaviour and properties of neutrinos in non-uniform nuclear matter, surrounded by electrons and other neutrinos are studied in the protoneutron star early stage characterized by trapped neutrinos. The nuclear matter itself is modelled by a relativistic mean-field approach, and models with both constant couplings and density-dependent couplings are considered. The so-called nuclear pasta phases at sub-saturation densities, described using the Thomas-Fermi approximation and solved in a Wigner-Seitz cell, are included in the calculation. We obtain the neutrino total cross section and mean free path, taking into account scattering and absorption processes and we compare the final results obtained with different parametrizations. The solution for this problem is important for the understanding of neutrino diffusion in a newly born neutron star after a supernovae explosion. It is shown that the pasta phase will increase the neutrino mean free path by as much as an order of magnitude, therefore contributing for shorter emission time-scales. (orig.)

  15. Neutrino diffusion in the pasta phase matter within the Thomas-Fermi approach

    International Nuclear Information System (INIS)

    Furtado, U.J.; Avancini, S.S.; Marinelli, J.R.; Martarello, W.; Providencia, C.

    2016-01-01

    The behaviour and properties of neutrinos in non-uniform nuclear matter, surrounded by electrons and other neutrinos are studied in the protoneutron star early stage characterized by trapped neutrinos. The nuclear matter itself is modelled by a relativistic mean-field approach, and models with both constant couplings and density-dependent couplings are considered. The so-called nuclear pasta phases at sub-saturation densities, described using the Thomas-Fermi approximation and solved in a Wigner-Seitz cell, are included in the calculation. We obtain the neutrino total cross section and mean free path, taking into account scattering and absorption processes and we compare the final results obtained with different parametrizations. The solution for this problem is important for the understanding of neutrino diffusion in a newly born neutron star after a supernovae explosion. It is shown that the pasta phase will increase the neutrino mean free path by as much as an order of magnitude, therefore contributing for shorter emission time-scales. (orig.)

  16. Characterization of short white matter fiber bundles in the central area from diffusion tensor MRI

    International Nuclear Information System (INIS)

    Magro, Elsa; Moreau, Tristan; Gibaud, Bernard; Seizeur, Romuald; Morandi, Xavier

    2012-01-01

    Diffusion tensor imaging and tractography allow studying white matter fiber bundles in the human brain in vivo. Electrophysiological studies and postmortem dissections permit improving our knowledge about the short association fibers connecting the pre- and postcentral gyri. The aim of this study was first to extract and analyze the features of these short fiber bundles and secondly to analyze their asymmetry according to the subjects' handedness. Ten right-handed and ten left-handed healthy subjects were included. White matter fiber bundles were extracted using a streamline tractography approach, with two seed regions of interest (ROI) taken from a parcellation of the pre- and postcentral gyri. This parcellation was achieved using T1 magnetic resonance images (MRI) and semi-automatically generated three ROIs within each gyrus. MRI tracks were reconstructed between all pairs of ROIs connecting the adjacent pre- and postcentral gyri. A quantitative analysis was performed on the number of tracks connecting each ROI pair. A statistical analysis studied the repartition of these MRI tracks in the right and left hemispheres and as a function of the subjects' handedness. The quantitative analysis showed an increased density of MRI tracks in the middle part of the central area in each hemisphere of the 20 subjects. The statistical analysis showed significantly more MRI tracks for the left hemisphere, when we consider the whole population, and this difference was presumably driven by the left-handers. These results raise questions about the functional role of these MRI tracks and their relation with laterality. (orig.)

  17. Differences in supratentorial white matter diffusion after radiotherapy - New biomarker of normal brain tissue damage?

    Energy Technology Data Exchange (ETDEWEB)

    Ravn, Soeren; Jens Broendum Froekaer, Jens [Dept. of Radiology, Aalborg Univ. Hospital, Aalborg (Denmark)], e-mail: sorl@rn.dk; Holmberg, Mats [Dept. of Oncology, Aalborg Univ. Hospital, Aalborg (Denmark); Soerensen, Preben [Dept. of Neurosurgery, Aalborg Univ. Hospital, Aalborg (Denmark); Carl, Jesper [Dept. of Neurosurgery, Aalborg Univ. Hospital, Aalborg (Denmark)

    2013-10-15

    Introduction: Therapy-induced injury to normal brain tissue is a concern in the treatment of all types of brain tumours. The purpose of this study was to investigate if magnetic resonance diffusion tensor imaging (DTI) could serve as a potential biomarker for the assessment of radiation-induced long-term white matter injury. Material and methods: DTI- and T1-weighted images of the brain were obtained in 19 former radiotherapy patients [nine men and 10 women diagnosed with astrocytoma (4), pituitary adenoma (6), meningioma (8) and craniopharyngioma (1), average age 57.8 (range 35-71) years]. Average time from radiotherapy to DTI scan was 4.6 (range 2.0-7.1) years. NordicICE software (NIC) was used to calculate apparent diffusion coefficient maps (ADC-maps). The co-registration between T1 images and ADC-maps were done using the auto function in NIC. The co-registration between the T1 images and the patient dose plans were done using the auto function in the treatment planning system Eclipse from Varian. Regions of interest were drawn on the T1-weighted images in NIC based on iso curves from Eclipse. Data was analysed by t-test. Estimates are given with 95 % CI. Results: A mean ADC difference of 4.6(0.3;8.9) X 10{sup -5} mm{sup 2}/s, p = 0.03 was found between paired white matter structures with a mean dose difference of 31.4 Gy. Comparing the ADC-values of the areas with highest dose from the paired data (dose > 33 Gy) with normal white matter (dose < 5 Gy) resulted in a mean dose difference of 44.1 Gy and a mean ADC difference of 7.87(3.15;12.60) X 10{sup -5} mm{sup 2}/s, p = 0.003. Following results were obtained when looking at differences between white matter mean ADC in average dose levels from 5 to 55 Gy in steps of 10 Gy with normal white matter mean ADC: 5 Gy; 1.91(-1.76;5.58) X 10{sup -5} mm{sup 2}/s, p = 0.29; 15 Gy; 5.81(1.53;10.11) X 10{sup -5} mm{sup 2}/s, p = 0.01; 25 Gy; 5.80(2.43;9.18) X 10{sup -5} mm{sup 2}/s, p = 0.002; 35 Gy; 5.93(2.89;8.97) X 10

  18. Quantization State of Baryonic Mass in Clusters of Galaxies

    Directory of Open Access Journals (Sweden)

    Potter F.

    2007-01-01

    Full Text Available The rotational velocity curves for clusters of galaxies cannot be explained by Newtonian gravitation using the baryonic mass nor does MOND succeed in reducing this discrepancy to acceptable differences. The dark matter hypothesis appears to offer a solution; however, non-baryonic dark matter has never been detected. As an alternative approach, quantum celestial mechanics (QCM predicts that galactic clusters are in quantization states determined solely by the total baryonic mass of the cluster and its total angular momentum. We find excellent agreement with QCM for ten galactic clusters, demonstrating that dark matter is not needed to explain the rotation velocities and providing further support to the hypothesis that all gravitationally bound systems have QCM quantization states.

  19. Radiation-Induced Changes in Normal-Appearing White Matter in Patients With Cerebral Tumors: A Diffusion Tensor Imaging Study

    International Nuclear Information System (INIS)

    Nagesh, Vijaya; Tsien, Christina I.; Chenevert, Thomas L.; Ross, Brian D.; Lawrence, Theodore S.; Junick, Larry; Cao Yue

    2008-01-01

    Purpose: To quantify the radiation-induced changes in normal-appearing white matter before, during, and after radiotherapy (RT) in cerebral tumor patients. Methods and Materials: Twenty-five patients with low-grade glioma, high-grade glioma, or benign tumor treated with RT were studied using diffusion tensor magnetic resonance imaging. The biologically corrected doses ranged from 50 to 81 Gy. The temporal changes were assessed before, during, and to 45 weeks after the start of RT. The mean diffusivity of water ( ), fractional anisotropy of diffusion, diffusivity perpendicular (λ perpendicular ) and parallel (λ parallel ) to white matter fibers were calculated in normal-appearing genu and splenium of the corpus callosum. Results: In the genu and splenium, fractional anisotropy decreased and , λ parallel , λ -perpendicular increased linearly and significantly with time (p -perpendicular had increased ∼30% in the genu and splenium, and λ parallel had increased 5% in the genu and 9% in the splenium, suggesting that demyelination is predominant. The increases in λ perpendicular and λ parallel were dose dependent, starting at 3 weeks and continuing to 32 weeks from the start of RT. The dose-dependent increase in λ perpendicular and λ parallel was not sustained after 32 weeks, indicating the transition from focal to diffuse effects. Conclusion: The acute and subacute changes in normal-appearing white matter fibers indicate radiation-induced demyelination and mild structural degradation of axonal fibers. The structural changes after RT are progressive, with early dose-dependent demyelination and subsequent diffuse dose-independent demyelination and mild axonal degradation. Diffusion tensor magnetic resonance imaging is potentially a biomarker for the assessment of radiation-induced white matter injury

  20. Tidal Dwarf Galaxies and Missing Baryons

    Directory of Open Access Journals (Sweden)

    Frederic Bournaud

    2010-01-01

    Full Text Available Tidal dwarf galaxies form during the interaction, collision, or merger of massive spiral galaxies. They can resemble “normal” dwarf galaxies in terms of mass, size, and become dwarf satellites orbiting around their massive progenitor. They nevertheless keep some signatures from their origin, making them interesting targets for cosmological studies. In particular, they should be free from dark matter from a spheroidal halo. Flat rotation curves and high dynamical masses may then indicate the presence of an unseen component, and constrain the properties of the “missing baryons,” known to exist but not directly observed. The number of dwarf galaxies in the Universe is another cosmological problem for which it is important to ascertain if tidal dwarf galaxies formed frequently at high redshift, when the merger rate was high, and many of them survived until today. In this paper, “dark matter” is used to refer to the nonbaryonic matter, mostly located in large dark halos, that is, CDM in the standard paradigm, and “missing baryons” or “dark baryons” is used to refer to the baryons known to exist but hardly observed at redshift zero, and are a baryonic dark component that is additional to “dark matter”.

  1. Diffuse-reflectance fourier-transform mid-infrared spectroscopy as a method of characterizing changes in soil organic matter

    Science.gov (United States)

    Diffuse-Reflectance Fourier-Transform Mid-Infrared Spectroscopy (MidIR) can identify the presence of important organic functional groups in soil organic matter (SOM). Soils contain myriad organic and inorganic components that absorb in the MidIR so spectral interpretation needs to be validated in or...

  2. Diffusion measures indicate fight exposure-related damage to cerebral white matter in boxers and mixed martial arts fighters.

    Science.gov (United States)

    Shin, W; Mahmoud, S Y; Sakaie, K; Banks, S J; Lowe, M J; Phillips, M; Modic, M T; Bernick, C

    2014-02-01

    Traumatic brain injury is common in fighting athletes such as boxers, given the frequency of blows to the head. Because DTI is sensitive to microstructural changes in white matter, this technique is often used to investigate white matter integrity in patients with traumatic brain injury. We hypothesized that previous fight exposure would predict DTI abnormalities in fighting athletes after controlling for individual variation. A total of 74 boxers and 81 mixed martial arts fighters were included in the analysis and scanned by use of DTI. Individual information and data on fight exposures, including number of fights and knockouts, were collected. A multiple hierarchical linear regression model was used in region-of-interest analysis to test the hypothesis that fight-related exposure could predict DTI values separately in boxers and mixed martial arts fighters. Age, weight, and years of education were controlled to ensure that these factors would not account for the hypothesized effects. We found that the number of knockouts among boxers predicted increased longitudinal diffusivity and transversal diffusivity in white matter and subcortical gray matter regions, including corpus callosum, isthmus cingulate, pericalcarine, precuneus, and amygdala, leading to increased mean diffusivity and decreased fractional anisotropy in the corresponding regions. The mixed martial arts fighters had increased transversal diffusivity in the posterior cingulate. The number of fights did not predict any DTI measures in either group. These findings suggest that the history of fight exposure in a fighter population can be used to predict microstructural brain damage.

  3. Altered Development of White Matter in Youth at High Familial Risk for Bipolar Disorder: A Diffusion Tensor Imaging Study

    Science.gov (United States)

    Versace, Amelia; Ladouceur, Cecile D.; Romero, Soledad; Birmaher, Boris; Axelson, David A.; Kupfer, David J.; Phillips, Mary L.

    2010-01-01

    Objective: To study white matter (WM) development in youth at high familial risk for bipolar disorder (BD). WM alterations are reported in youth and adults with BD. WM undergoes important maturational changes in adolescence. Age-related changes in WM microstructure using diffusion tensor imaging with tract-based spatial statistics in healthy…

  4. Tract-Specific Analyses of Diffusion Tensor Imaging Show Widespread White Matter Compromise in Autism Spectrum Disorder

    Science.gov (United States)

    Shukla, Dinesh K.; Keehn, Brandon; Muller, Ralph-Axel

    2011-01-01

    Background: Previous diffusion tensor imaging (DTI) studies have shown white matter compromise in children and adults with autism spectrum disorder (ASD), which may relate to reduced connectivity and impaired function of distributed networks. However, tract-specific evidence remains limited in ASD. We applied tract-based spatial statistics (TBSS)…

  5. Baryons with functional methods

    International Nuclear Information System (INIS)

    Fischer, Christian S.

    2017-01-01

    We summarise recent results on the spectrum of ground-state and excited baryons and their form factors in the framework of functional methods. As an improvement upon similar approaches we explicitly take into account the underlying momentum-dependent dynamics of the quark-gluon interaction that leads to dynamical chiral symmetry breaking. For light octet and decuplet baryons we find a spectrum in very good agreement with experiment, including the level ordering between the positive- and negative-parity nucleon states. Comparing the three-body framework with the quark-diquark approximation, we do not find significant differences in the spectrum for those states that have been calculated in both frameworks. This situation is different in the electromagnetic form factor of the Δ, which may serve to distinguish both pictures by comparison with experiment and lattice QCD.

  6. Photoproduction of charmed baryons

    International Nuclear Information System (INIS)

    Russell, J.J.

    1980-01-01

    The results of a search for the photoproduction of charmed baryons in the broad-band neutral beam at Fermi National Accelerator Laboratory are reported. The lowest lying charmed baryon (Λ/sub c/ + ) is observed through its decay to p-anti K 0 . The cross section times branching ratio of γ + C → Λ/sub c/ + + X, γ + C → p + anti K 0 is measured to be sigma B = 3 nanobarns/nucleon. The total error on this measurement is estimated to be -20% to +40%. The mass of the Λ/sub c/ + is found to be 2.284 +- 0.001 GeV/c 2 , in good agreement with the Mark II result from SPEAR. Upper limits (90% confidence level) are set on sigma B for the modes Λ 0 π, Λ 0 πππ, pKπ

  7. Baryons as solitons

    International Nuclear Information System (INIS)

    Walliser, Hans

    2000-01-01

    Chiral Lagrangians as effective field theories of QCD are successfully applied to meson physics in the framework of chiral perturbation theory. Because of their nonlinear structure these Lagrangians allow for static soliton solutions interpreted as baryons. Their semiclassical quantization, which provides the leading order in an 1/N C expansion with N C the number of colors, turned out to be insufficient to obtain satisfactory agreement with empirical baryon observables. However with N C =3, large corrections are expected in the next-to-leading order carried by mesonic fluctuations around the soliton background, which require renormalization to 1-loop. In contrast to chiral perturbation theory, the low-energy Lagrangian proves inapt and terms with an arbitrary number of gradients may in principle contribute. Assumptions about the a priori unknown higher chiral orders are tested by the scale-dependence of the results. For example, in the simple Sine-Gordon model with 1 scalar field in 1+1 dimensions, knowledge of the low-energy behavior together with the mere existence of an underlying 1-loop renormalizable scale-independent solitonic theory is sufficient to regain the full solution. Baryonic observables calculated within that framework generally lead to better agreement with experiment except for the axial quantities. For these quantities the 1/N C expansion does not converge sufficiently fast because the current algebra mixes different N C orders

  8. Diffusion Tensor Imaging of Normal-Appearing White Matter as Biomarker for Radiation-Induced Late Delayed Cognitive Decline

    International Nuclear Information System (INIS)

    Chapman, Christopher H.; Nagesh, Vijaya; Sundgren, Pia C.; Buchtel, Henry; Chenevert, Thomas L.; Junck, Larry; Lawrence, Theodore S.; Tsien, Christina I.; Cao, Yue

    2012-01-01

    Purpose: To determine whether early assessment of cerebral white matter degradation can predict late delayed cognitive decline after radiotherapy (RT). Methods and Materials: Ten patients undergoing conformal fractionated brain RT participated in a prospective diffusion tensor magnetic resonance imaging study. Magnetic resonance imaging studies were acquired before RT, at 3 and 6 weeks during RT, and 10, 30, and 78 weeks after starting RT. The diffusivity variables in the parahippocampal cingulum bundle and temporal lobe white matter were computed. A quality-of-life survey and neurocognitive function tests were administered before and after RT at the magnetic resonance imaging follow-up visits. Results: In both structures, longitudinal diffusivity (λ ‖ ) decreased and perpendicular diffusivity (λ ⊥ ) increased after RT, with early changes correlating to later changes (p ⊥ at 3 weeks, and patients with >50% of cingula volume receiving >12 Gy had a greater increase in λ ⊥ at 3 and 6 weeks (p ‖ (30 weeks, p ‖ changes predicted for post-RT changes in verbal recall scores (3 and 6 weeks, p < .05). The neurocognitive test scores correlated significantly with the quality-of-life survey results. Conclusions: The correlation between early diffusivity changes in the parahippocampal cingulum and the late decline in verbal recall suggests that diffusion tensor imaging might be useful as a biomarker for predicting late delayed cognitive decline.

  9. Age-related Differences in White Matter Integrity in Healthy Human Brain: Evidence from Structural Mri and Diffusion Tensor Imaging

    Directory of Open Access Journals (Sweden)

    Rishu Rathee

    2016-01-01

    Full Text Available The aim is to investigate the relationship between microstructural white matter (WM diffusivity indices and macrostructural WM volume (WMV among healthy individuals (20–85 years. Whole-brain diffusion measures were calculated from diffusion tensor imaging using FMRIB software library while WMV was estimated through voxel-based morphometry, and voxel-based analysis was carried out using tract-based spatial statistics. Our results revealed that mean diffusivity, axial diffusivity, and radial diffusivity had shown good correlation with WMV but not for fractional anisotropy (FA. Voxel-wise tract-based spatial statistics analysis for FA showed a significant decrease in four regions for middle-aged group compared to young-aged group, in 22 regions for old-aged group compared to middle-aged group, and in 26 regions for old-aged group compared to young-aged group ( P < 0.05. We found significantly lower WMV, FA, and mean diffusivity values in females than males and inverted-U trend for FA in males. We conclude differential age- and gender-related changes for structural WMV and WM diffusion indices.

  10. Dark Matter

    Directory of Open Access Journals (Sweden)

    Einasto J.

    2011-06-01

    Full Text Available I give a review of the development of the concept of dark matter. The dark matter story passed through several stages from a minor observational puzzle to a major challenge for theory of elementary particles. Modern data suggest that dark matter is the dominant matter component in the Universe, and that it consists of some unknown non-baryonic particles. Dark matter is the dominant matter component in the Universe, thus properties of dark matter particles determine the structure of the cosmic web.

  11. Characterization of short white matter fiber bundles in the central area from diffusion tensor MRI

    Energy Technology Data Exchange (ETDEWEB)

    Magro, Elsa [INSERM U 1099/Universite de Rennes 1, Equipe MediCIS, Faculte de Medecine, Rennes Cedex (France); CHU Cavale Blanche, Service de Neurochirurgie, Pole Neurolocomoteur, Brest (France); Moreau, Tristan; Gibaud, Bernard [INSERM U 1099/Universite de Rennes 1, Equipe MediCIS, Faculte de Medecine, Rennes Cedex (France); Seizeur, Romuald [INSERM U 1099/Universite de Rennes 1, Equipe MediCIS, Faculte de Medecine, Rennes Cedex (France); CHU Cavale Blanche, Service de Neurochirurgie, Pole Neurolocomoteur, Brest (France); INSERM UMR 1101 LaTIM, Brest (France); Morandi, Xavier [INSERM U 1099/Universite de Rennes 1, Equipe MediCIS, Faculte de Medecine, Rennes Cedex (France); CHU Pontchaillou, Service de Neurochirurgie, Rennes (France)

    2012-11-15

    Diffusion tensor imaging and tractography allow studying white matter fiber bundles in the human brain in vivo. Electrophysiological studies and postmortem dissections permit improving our knowledge about the short association fibers connecting the pre- and postcentral gyri. The aim of this study was first to extract and analyze the features of these short fiber bundles and secondly to analyze their asymmetry according to the subjects' handedness. Ten right-handed and ten left-handed healthy subjects were included. White matter fiber bundles were extracted using a streamline tractography approach, with two seed regions of interest (ROI) taken from a parcellation of the pre- and postcentral gyri. This parcellation was achieved using T1 magnetic resonance images (MRI) and semi-automatically generated three ROIs within each gyrus. MRI tracks were reconstructed between all pairs of ROIs connecting the adjacent pre- and postcentral gyri. A quantitative analysis was performed on the number of tracks connecting each ROI pair. A statistical analysis studied the repartition of these MRI tracks in the right and left hemispheres and as a function of the subjects' handedness. The quantitative analysis showed an increased density of MRI tracks in the middle part of the central area in each hemisphere of the 20 subjects. The statistical analysis showed significantly more MRI tracks for the left hemisphere, when we consider the whole population, and this difference was presumably driven by the left-handers. These results raise questions about the functional role of these MRI tracks and their relation with laterality. (orig.)

  12. White matter and reading deficits after pediatric traumatic brain injury: A diffusion tensor imaging study

    Directory of Open Access Journals (Sweden)

    Chad Parker Johnson

    2015-01-01

    Full Text Available Pediatric traumatic brain injury often results in significant long-term deficits in mastery of reading ability. This study aimed to identify white matter pathways that, when damaged, predicted reading deficits in children. Based on the dual-route model of word reading, we predicted that integrity of the inferior fronto-occipital fasciculus would be related to performance in sight word identification while integrity of the superior longitudinal fasciculus would be related to performance in phonemic decoding. Reading fluency and comprehension were hypothesized to relate to the superior longitudinal fasciculus, inferior fronto-occipital fasciculus, and cingulum bundle. The connectivity of white matter pathways was used to predict reading deficits in children aged 6 to 16 years with traumatic brain injury (n = 29 and those with orthopedic injury (n = 27 using tract-based spatial statistics. Results showed that children with traumatic brain injury and reduced microstructural integrity of the superior longitudinal fasciculus demonstrated reduced word-reading ability on sight word and phonemic decoding tasks. Additionally, children with traumatic brain injury and microstructural changes involving the cingulum bundle demonstrated reduced reading fluency. Results support the association of a dorsal pathway via the superior longitudinal fasciculus with both sight word reading and phonemic decoding. No association was identified between the inferior fronto-occipital fasciculus and sight word reading or phonemic decoding. Reading fluency was associated with the integrity of the cingulum bundle. These findings support dissociable pathways predicting word reading and fluency using Diffusion Tensor Imaging and provide additional information for developing models of acquired reading deficits by specifying areas of brain damage which may predict reading deficits following recovery from the acute phase of TBI.

  13. Comparing a diffusion tensor and non-tensor approach to white matter fiber tractography in chronic stroke.

    Science.gov (United States)

    Auriat, A M; Borich, M R; Snow, N J; Wadden, K P; Boyd, L A

    2015-01-01

    Diffusion tensor imaging (DTI)-based tractography has been used to demonstrate functionally relevant differences in white matter pathway status after stroke. However, it is now known that the tensor model is insensitive to the complex fiber architectures found in the vast majority of voxels in the human brain. The inability to resolve intra-voxel fiber orientations may have important implications for the utility of standard DTI-based tract reconstruction methods. Intra-voxel fiber orientations can now be identified using novel, tensor-free approaches. Constrained spherical deconvolution (CSD) is one approach to characterize intra-voxel diffusion behavior. In the current study, we performed DTI- and CSD-based tract reconstruction of the corticospinal tract (CST) and corpus callosum (CC) to test the hypothesis that characterization of complex fiber orientations may improve the robustness of fiber tract reconstruction and increase the sensitivity to identify functionally relevant white matter abnormalities in individuals with chronic stroke. Diffusion weighted magnetic resonance imaging was performed in 27 chronic post-stroke participants and 12 healthy controls. Transcallosal pathways and the CST bilaterally were reconstructed using DTI- and CSD-based tractography. Mean fractional anisotropy (FA), apparent diffusion coefficient (ADC), axial diffusivity (AD), and radial diffusivity (RD) were calculated across the tracts of interest. The total number and volume of reconstructed tracts was also determined. Diffusion measures were compared between groups (Stroke, Control) and methods (CSD, DTI). The relationship between post-stroke motor behavior and diffusion measures was evaluated. Overall, CSD methods identified more tracts than the DTI-based approach for both CC and CST pathways. Mean FA, ADC, and RD differed between DTI and CSD for CC-mediated tracts. In these tracts, we discovered a difference in FA for the CC between stroke and healthy control groups using CSD but

  14. Comparing a diffusion tensor and non-tensor approach to white matter fiber tractography in chronic stroke

    Directory of Open Access Journals (Sweden)

    A.M. Auriat

    2015-01-01

    Full Text Available Diffusion tensor imaging (DTI-based tractography has been used to demonstrate functionally relevant differences in white matter pathway status after stroke. However, it is now known that the tensor model is insensitive to the complex fiber architectures found in the vast majority of voxels in the human brain. The inability to resolve intra-voxel fiber orientations may have important implications for the utility of standard DTI-based tract reconstruction methods. Intra-voxel fiber orientations can now be identified using novel, tensor-free approaches. Constrained spherical deconvolution (CSD is one approach to characterize intra-voxel diffusion behavior. In the current study, we performed DTI- and CSD-based tract reconstruction of the corticospinal tract (CST and corpus callosum (CC to test the hypothesis that characterization of complex fiber orientations may improve the robustness of fiber tract reconstruction and increase the sensitivity to identify functionally relevant white matter abnormalities in individuals with chronic stroke. Diffusion weighted magnetic resonance imaging was performed in 27 chronic post-stroke participants and 12 healthy controls. Transcallosal pathways and the CST bilaterally were reconstructed using DTI- and CSD-based tractography. Mean fractional anisotropy (FA, apparent diffusion coefficient (ADC, axial diffusivity (AD, and radial diffusivity (RD were calculated across the tracts of interest. The total number and volume of reconstructed tracts was also determined. Diffusion measures were compared between groups (Stroke, Control and methods (CSD, DTI. The relationship between post-stroke motor behavior and diffusion measures was evaluated. Overall, CSD methods identified more tracts than the DTI-based approach for both CC and CST pathways. Mean FA, ADC, and RD differed between DTI and CSD for CC-mediated tracts. In these tracts, we discovered a difference in FA for the CC between stroke and healthy control groups

  15. Detectors calibration and research of luminescent materials for non baryonic dark matter detection; Calibration de detecteurs et recherche de materiaux luminescents pour la detection de la matiere noire non baryonique

    Energy Technology Data Exchange (ETDEWEB)

    Messous, M.Y.

    1995-03-01

    This work is dedicated to the characterization of luminescent materials in order to build bolometers for the simultaneous detection of heat an light in the search for WIMPs (Weakly Interacting Massive Particles) candidates for non baryonic dark matter. These double bolometers should enable the identification and measurement of recoil ions after collision between a WIMPs and material nucleus. In our search for highly luminescent materials, we have studied the emission spectra, the time response and the spectra response resulting from laser excitation or ionizing particles bombardment of some crystals such as CaF{sub 2}(Eu), CaF{sub 2}, CeF{sub 3}(Ce) and In{sub 2}Si{sub 2}O{sub 7}. These studies were conducted down to liquid Helium temperature (4 K). After showing the good performance of CaF{sub 2}(Eu) scintillator, we have measured the quenching effect resulting from {sup 19}F and Ca ions recoil in CaF{sub 2}(Eu). This was done at the 14 MeV Tandem accelerator of Bruyeres-Le-Chatel with a pulsed neutron beam, simulating the WIMPs. The data obtained allowed the exploitation of the results of the BPRS (Beijing - Rome - Paris - Saclay) experiments carried out at Gran-Sasso. This results showed a gain of up to an order of magnitude in the exclusion graph of axially coupled WIMPs compared to NaI. With the apparatus developed at IPN Lyon (Nuclear Physical Institute of Lyon), we have also measured the ionization induced by Ge ion recoils in Germanium detector, which is one of the most promising crystals for WIMPs detection in the energy range of 2.8 keV-37.8 keV. An ionization efficiency of 24% to 29% was obtained. (author). refs., figs., tabs.

  16. White-matter tract abnormalities and antisocial behavior: A systematic review of diffusion tensor imaging studies across development

    Directory of Open Access Journals (Sweden)

    Rebecca Waller

    2017-01-01

    Full Text Available Antisocial behavior (AB, including aggression, violence, and theft, is thought be underpinned by abnormal functioning in networks of the brain critical to emotion processing, behavioral control, and reward-related learning. To better understand the abnormal functioning of these networks, research has begun to investigate the structural connections between brain regions implicated in AB using diffusion tensor imaging (DTI, which assesses white-matter tract microstructure. This systematic review integrates findings from 22 studies that examined the relationship between white-matter microstructure and AB across development. In contrast to a prior hypothesis that AB is associated with greater diffusivity specifically in the uncinate fasciculus, findings suggest that adult AB is associated with greater diffusivity across a range of white-matter tracts, including the uncinate fasciculus, inferior fronto-occipital fasciculus, cingulum, corticospinal tract, thalamic radiations, and corpus callosum. The pattern of findings among youth studies was inconclusive with both higher and lower diffusivity found across association, commissural, and projection and thalamic tracts.

  17. Baryons in the heavy quark effective theory

    International Nuclear Information System (INIS)

    Mannel, T.; Roberts, W.; Ryzak, Z.

    1990-08-01

    We show how to incorporate baryons in the heavy quark effective theory. A convenient formalism is exhibited and applied to semileptonic weak decays of heavy baryons and to exclusive production of heavy baryons in e + e - annihilation. (orig.)

  18. Normal development of human brain white matter from infancy to early adulthood: a diffusion tensor imaging study.

    Science.gov (United States)

    Uda, Satoshi; Matsui, Mie; Tanaka, Chiaki; Uematsu, Akiko; Miura, Kayoko; Kawana, Izumi; Noguchi, Kyo

    2015-01-01

    Diffusion tensor imaging (DTI), which measures the magnitude of anisotropy of water diffusion in white matter, has recently been used to visualize and quantify parameters of neural tracts connecting brain regions. In order to investigate the developmental changes and sex and hemispheric differences of neural fibers in normal white matter, we used DTI to examine 52 healthy humans ranging in age from 2 months to 25 years. We extracted the following tracts of interest (TOIs) using the region of interest method: the corpus callosum (CC), cingulum hippocampus (CGH), inferior longitudinal fasciculus (ILF), and superior longitudinal fasciculus (SLF). We measured fractional anisotropy (FA), apparent diffusion coefficient (ADC), axial diffusivity (AD), and radial diffusivity (RD). Approximate values and changes in growth rates of all DTI parameters at each age were calculated and analyzed using LOESS (locally weighted scatterplot smoothing). We found that for all TOIs, FA increased with age, whereas ADC, AD and RD values decreased with age. The turning point of growth rates was at approximately 6 years. FA in the CC was greater than that in the SLF, ILF and CGH. Moreover, FA, ADC and AD of the splenium of the CC (sCC) were greater than in the genu of the CC (gCC), whereas the RD of the sCC was lower than the RD of the gCC. The FA of right-hemisphere TOIs was significantly greater than that of left-hemisphere TOIs. In infants, growth rates of both FA and RD were larger than those of AD. Our data show that developmental patterns differ by TOIs and myelination along with the development of white matter, which can be mainly expressed as an increase in FA together with a decrease in RD. These findings clarify the long-term normal developmental characteristics of white matter microstructure from infancy to early adulthood. © 2015 S. Karger AG, Basel.

  19. Shades of white : diffusion properties of T1- and FLAIR-defined white matter signal abnormalities differ in stages from cognitively normal to dementia

    NARCIS (Netherlands)

    Riphagen, Joost M.; Gronenschild, Ed HBM; Salat, David H.; Freeze, Whitney M.; Ivanov, Dimo; Clerx, Lies; Verhey, Frans R. J.; Aalten, Pauline; Jacobs, Heidi I. L.

    The underlying pathology of white matter signal abnormalities (WMSAs) is heterogeneous and may vary dependent on the magnetic resonance imaging contrast used to define them. We investigated differences in white matter diffusivity as an indicator for white matter integrity underlying WMSA based on

  20. Baryon distribution in relativistic heavy-ion collisions

    International Nuclear Information System (INIS)

    Wong, C.

    1984-01-01

    In order to determine whether a pure quark-gluon plasma with no net baryon density can be formed in the central rapidity region in relativistic heavy-ion collisions, we estimate the baryon distribution by using a Glauber-type multiple-collision model in which the nucleons of one nucleus degrade in energy as they make collisions with nucleons in the other nucleus. As a test of this model, we study first nucleon-nucleus collisions at 100 GeV/c and compare the theoretical results with the experimental data of Barton et al. The results are then generalized to study the baryon distribution in nucleus-nucleus collisions. It is found that in the head-on collision of two heavy nuclei (A> or approx. =100), the baryon rapidity distributions have broad peaks and extend well into the central rapidity region. The energy density of the baryon in the central rapidity region is about 5--6 % of the total energy density at a center-of-mass energy of 30 GeV per nucleon and decreases to about 2--3 % at a center-of-mass energy of 100 GeV per nucleon. The stopping power for a baryon in nuclear matter is extracted

  1. Effect of pre-existing baryon inhomogeneities on the dynamics of ...

    Indian Academy of Sciences (India)

    by the effects of neutrino inflation and baryon diffusion. However, even ... small lump, will increase in size as the phase transition proceeds. Due to this ... happen that the bubble nucleation rate itself will be different in the two regions. However,.

  2. Blue-Light Therapy following Mild Traumatic Brain Injury: Effects on White Matter Water Diffusion in the Brain

    Directory of Open Access Journals (Sweden)

    Sahil Bajaj

    2017-11-01

    Full Text Available Mild traumatic brain injury (mTBI is a common and often inconspicuous wound that is frequently associated with chronic low-grade symptoms and cognitive dysfunction. Previous evidence suggests that daily blue wavelength light therapy may be effective at reducing fatigue and improving sleep in patients recovering from mTBI. However, the effects of light therapy on recovering brain structure remain unexplored. In this study, we analyzed white matter diffusion properties, including generalized fractional anisotropy, and the quantity of water diffusion in isotropic (i.e., isotropic diffusion and anisotropic fashion (i.e., quantitative anisotropy, QA for fibers crossing 11 brain areas known to be significantly affected following mTBI. Specifically, we investigated how 6 weeks of daily morning blue light exposure therapy (compared to an amber-light placebo condition impacted changes in white matter diffusion in individuals with mTBI. We observed a significant impact of the blue light treatment (relative to the placebo on the amount of water diffusion (QA for multiple brain areas, including the corpus callosum, anterior corona radiata, and thalamus. Moreover, many of these changes were associated with improvements in sleep latency and delayed memory. These findings suggest that blue wavelength light exposure may serve as one of the potential non-pharmacological treatments for facilitating structural and functional recovery following mTBI; they also support the use of QA as a reliable neuro-biomarker for mTBI therapies.

  3. Characteristics of lesional and extra-lesional cortical grey matter in relapsing-remitting and secondary progressive multiple sclerosis: A magnetisation transfer and diffusion tensor imaging study.

    Science.gov (United States)

    Yaldizli, Özgür; Pardini, Matteo; Sethi, Varun; Muhlert, Nils; Liu, Zheng; Tozer, Daniel J; Samson, Rebecca S; Wheeler-Kingshott, Claudia Am; Yousry, Tarek A; Miller, David H; Chard, Declan T

    2016-02-01

    In multiple sclerosis (MS), diffusion tensor and magnetisation transfer imaging are both abnormal in lesional and extra-lesional cortical grey matter, but differences between clinical subtypes and associations with clinical outcomes have only been partly assessed. To compare mean diffusivity, fractional anisotropy and magnetisation transfer ratio (MTR) in cortical grey matter lesions (detected using phase-sensitive inversion recovery (PSIR) imaging) and extra-lesional cortical grey matter, and assess associations with disability in relapse-onset MS. Seventy-two people with MS (46 relapsing-remitting (RR), 26 secondary progressive (SP)) and 36 healthy controls were included in this study. MTR, mean diffusivity and fractional anisotropy were measured in lesional and extra-lesional cortical grey matter. Mean fractional anisotropy was higher and MTR lower in lesional compared with extra-lesional cortical grey matter. In extra-lesional cortical grey matter mean fractional anisotropy and MTR were lower, and mean diffusivity was higher in the MS group compared with controls. Mean MTR was lower and mean diffusivity was higher in lesional and extra-lesional cortical grey matter in SPMS when compared with RRMS. These differences were independent of disease duration. In multivariate analyses, MTR in extra-lesional more so than lesional cortical grey matter was associated with disability. Magnetic resonance abnormalities in lesional and extra-lesional cortical grey matter are greater in SPMS than RRMS. Changes in extra-lesional compared with lesional cortical grey matter are more consistently associated with disability. © The Author(s), 2015.

  4. Transition mixing among baryons

    International Nuclear Information System (INIS)

    Faiman, D.

    1976-01-01

    A degenerate perturbation theory model for mass splitting within the 70,1 - baryon multiplet is proposed. It is found that dominance of the lowest-lying two-body 56x35 intermediate states produces mixing angles in fair approximation to those previously deduced from SU(6)sub(W) analysis of decay data. The prediction of the couplings of all hitherto undetected members of the multiplet and of mass were made. The results call into question the nature of Λ (1405). (author)

  5. Unstable baryons without Guts

    International Nuclear Information System (INIS)

    Uschersohn, J.; Elbaz, E.

    1983-01-01

    In the rishon model the leptons and the quarks can be classified in either doublets or quadruplets of a SU(2) group. Gauge invariance leads to different charged current interactions in the doublet and the quadruplet cases. Demanding that the neutral currents be the same in the two cases, one obtains relations between the different charged current couplings to leptons and quark; moreover, if these transform as linear combinations of doublets and quadruplets, one can estimate the mass of the gauge boson responsible for baryon decay to be not larger than 10 5 GeV. A SU(2)sub(L) x U(1) model is treated in detail

  6. Baryon spectroscopy at KAON

    Energy Technology Data Exchange (ETDEWEB)

    Comyn, Martin

    1992-07-01

    The unique opportunities for the study of baryon spectroscopy at the TRIUMF KAON Factory are outlined. Related issues in other areas of hadron spectroscopy are discussed. The complex of accelerators that comprise the TRIUMF KAON Factory, and the properties of the separated beams that will be available to experimenters, are described. Initial design considerations for detectors to be used in the study of hadron spectroscopy are presented, along with a proposed detector configuration. The progress towards realization of the TRIUMF KAON Factory is examined, and the timetable for the determination of the initial experimental programme and facilities is explained. 23 refs., 4 figs., 5 tabs.

  7. The origin of matter

    International Nuclear Information System (INIS)

    Cline, J.

    2004-01-01

    The author presents the issue of how matter triumphed over anti-matter in the formation of the universe. Theories focus on the nature of asymmetry that might have created an excess of matter over anti-matter. Sakharov and Kuzmin listed 3 conditions that must be met for baryogenesis to take place. First the baryon number must not be conserved: there must be some interactions that change the number of baryons, baryon-number violation can rise from an interaction between quarks and leptons. Secondly, 2 symmetries that relate particles to antiparticles must be violated. The CP violation in Kaon decay is too weak to create enough baryon asymmetry, so physicists believe that larger sources of CP violation await discovery. Thirdly, there must be the loss of thermal equilibrium of the universe. In thermal equilibrium, baryons are decaying but inverse processes are also taking place, quarks are fusing to form baryons, rates being equal no baryon asymmetry is generated. But if thermal equilibrium is broken, to say temperature is decreasing, at a certain temperature a pair of quarks will no longer have enough energy to produce a heavy particle which generates baryon asymmetry. (A.C.)

  8. Hyperons: Insights into baryon structures

    International Nuclear Information System (INIS)

    Lach, J.

    1991-08-01

    The baryon octet is composed mainly of hyperons. Modern high energy hyperon beams provide a tool for the study of hyperon static properties and interactions. Experiments with these beams have provided new insights into hyperon rare decays, magnetic moments, and interactions. These experiments provide us with insights into the strong, weak, and electromagnetic structure of the baryons. 65 refs., 45 figs., 5 tabs

  9. Anomalous Dimensions of Conformal Baryons

    DEFF Research Database (Denmark)

    Pica, Claudio; Sannino, Francesco

    2016-01-01

    We determine the anomalous dimensions of baryon operators for the three color theory as function of the number of massless flavours within the conformal window to the maximum known order in perturbation theory. We show that the anomalous dimension of the baryon is controllably small, within...

  10. Finite temperature system of strongly interacting baryons

    International Nuclear Information System (INIS)

    Bowers, R.L.; Gleeson, A.M.; Pedigo, R.D.; Wheeler, J.W.

    1976-07-01

    A fully relativistic finite temperature many body theory is constructed and used to examine the bulk properties of a system of strongly interacting baryons. The strong interactions are described by a two parameter phenomenological model fit to a simple description of nuclear matter at T = 0. The zero temperature equation of state for such a system which has already been discussed in the literature was developed to give a realistic description of nuclear matter. The model presented here is the exact finite temperature extension of that model. The effect of the inclusion of baryon pairs for T greater than or equal to 2mc 2 /k is discussed in detail. The phase transition identified with nuclear matter vanishes for system temperatures in excess of T/sub C/ = 1.034 x 10 11 0 K. All values of epsilon (P,T) correspond to systems that are causal in the sense that the locally determined speed of sound never exceeds the speed of light

  11. Finite temperature system of strongly interacting baryons

    Energy Technology Data Exchange (ETDEWEB)

    Bowers, R.L.; Gleeson, A.M.; Pedigo, R.D.; Wheeler, J.W.

    1976-07-01

    A fully relativistic finite temperature many body theory is constructed and used to examine the bulk properties of a system of strongly interacting baryons. The strong interactions are described by a two parameter phenomenological model fit to a simple description of nuclear matter at T = 0. The zero temperature equation of state for such a system which has already been discussed in the literature was developed to give a realistic description of nuclear matter. The model presented here is the exact finite temperature extension of that model. The effect of the inclusion of baryon pairs for T greater than or equal to 2mc/sup 2//k is discussed in detail. The phase transition identified with nuclear matter vanishes for system temperatures in excess of T/sub C/ = 1.034 x 10/sup 11/ /sup 0/K. All values of epsilon (P,T) correspond to systems that are causal in the sense that the locally determined speed of sound never exceeds the speed of light.

  12. A Baryonic Solution to the Missing Satellites Problem

    Energy Technology Data Exchange (ETDEWEB)

    Brooks, Alyson M.; Kuhlen, Michael; Zolotov, Adi; Hooper, Dan

    2013-03-01

    It has been demonstrated that the inclusion of baryonic physics can alter the dark matter densities in the centers of low-mass galaxies, making the central dark matter slope more shallow than predicted in pure cold dark matter simulations. This flattening of the dark matter profile can occur in the most luminous subhalos around Milky Way mass galaxies. Zolotov et al. have suggested a correction to be applied to the central masses of dark matter-only satellites in order to mimic the affect of (1) the flattening of the dark matter cusp due to supernova feedback in luminous satellites and (2) enhanced tidal stripping due to the presence of a baryonic disk. In this paper, we apply this correction to the z = 0 subhalo masses from the high resolution, dark matter-only Via Lactea II (VL2) simulation, and find that the number of massive subhalos is dramatically reduced. After adopting a stellar mass to halo mass relationship for the VL2 halos, and identifying subhalos that are (1) likely to be destroyed by stripping and (2) likely to have star formation suppressed by photo-heating, we find that the number of massive, luminous satellites around a Milky Way mass galaxy is in agreement with the number of observed satellites around the Milky Way or M31. We conclude that baryonic processes have the potential to solve the missing satellites problem

  13. Quantification of diffusion tensor imaging in normal white matter maturation of early childhood using an automated processing pipeline.

    Science.gov (United States)

    Loh, K B; Ramli, N; Tan, L K; Roziah, M; Rahmat, K; Ariffin, H

    2012-07-01

    The degree and status of white matter myelination can be sensitively monitored using diffusion tensor imaging (DTI). This study looks at the measurement of fractional anistropy (FA) and mean diffusivity (MD) using an automated ROI with an existing DTI atlas. Anatomical MRI and structural DTI were performed cross-sectionally on 26 normal children (newborn to 48 months old), using 1.5-T MRI. The automated processing pipeline was implemented to convert diffusion-weighted images into the NIfTI format. DTI-TK software was used to register the processed images to the ICBM DTI-81 atlas, while AFNI software was used for automated atlas-based volumes of interest (VOIs) and statistical value extraction. DTI exhibited consistent grey-white matter contrast. Triphasic temporal variation of the FA and MD values was noted, with FA increasing and MD decreasing rapidly early in the first 12 months. The second phase lasted 12-24 months during which the rate of FA and MD changes was reduced. After 24 months, the FA and MD values plateaued. DTI is a superior technique to conventional MR imaging in depicting WM maturation. The use of the automated processing pipeline provides a reliable environment for quantitative analysis of high-throughput DTI data. Diffusion tensor imaging outperforms conventional MRI in depicting white matter maturation. • DTI will become an important clinical tool for diagnosing paediatric neurological diseases. • DTI appears especially helpful for developmental abnormalities, tumours and white matter disease. • An automated processing pipeline assists quantitative analysis of high throughput DTI data.

  14. Homogeneity based segmentation and enhancement of Diffusion Tensor Images : a white matter processing framework

    NARCIS (Netherlands)

    Rodrigues, P.R.

    2011-01-01

    In diffusion magnetic resonance imaging (DMRI) the Brownian motion of the water molecules, within biological tissue, is measured through a series of images. In diffusion tensor imaging (DTI) this diffusion is represented using tensors. DTI describes, in a non-invasive way, the local anisotropy

  15. New MRI technologies. Diffusion MRI and its application to functional neuroimaging and analyses of white matter integrity

    International Nuclear Information System (INIS)

    Kobayashi, Tetsuo

    2010-01-01

    Described is the technological aspect of MRI, MR diffusion-weighted imaging (MR-DWI), principles of its measurement and application for imaging the cerebral function and for aiding the quantitative diagnosis of brain diseases. The author explains the principle of MR imaging process; diffusion properties of water molecules, MR-DWI based on them and DW-fMRI of the brain; MR-diffusion tensor imaging (MR-DTI), its analysis and color acquisition, and tracking of white matter nerve fibers; analysis of white matter lesions by the tracking; and the new tracking method at the chiasm of nerve fascicles. The usual fMRI reflects the blood oxygen level depending (BOLD) signals whereas recently attracted DW-fMRI, the volume changes of nerve cells concomitant to nerve activation accompanying apparent changes of water diffusion coefficients in and out of cells which occur faster than BOLD signs, resulting in higher resolution of time and space. However, DWI requires the higher intensity of static magnetic field like 3T. MR-DTI acquires the anisotropic diffusion of water molecules using MR-DWI technique with application of 6 or more motion probing gradients, thus makes it possible to track the running directions of nerve fibers and capillary vessels, and is proposed to be a useful mean of specific fiber tracking in the white matter when displayed by 3 different colors exhibiting the directions like the right/left (x axis, red), anterior/posterior (y, green) and upper/lower (z, blue) sides of head. Recently, MR-DWI and MR-DTI have been found usable for pathogenic studies of brain diseases such as dementia. Tensor anisotropy is apparently lowered at the chiasm of nerve fascicles, the cause of tracking error, for which authors have developed a new method using the similarity of directional vector, not of tensor, before and behind the chiasm. As exemplified, MRI technology is further advancing even at present. (T.T.)

  16. Early microstructural white matter changes in patients with HIV: A diffusion tensor imaging study

    Directory of Open Access Journals (Sweden)

    Stubbe-Drger Bianca

    2012-05-01

    Full Text Available Abstract Background Previous studies have reported white matter (WM brain alterations in asymptomatic patients with human immunodeficiency virus (HIV. Methods We compared diffusion tensor imaging (DTI derived WM fractional anisotropy (FA between HIV-patients with and without mild macroscopic brain lesions determined using standard magnetic resonance imaging (MRI. We furthermore investigated whether WM alterations co-occurred with neurocognitive deficits and depression. We performed structural MRI and DTI for 19 patients and 19 age-matched healthy controls. Regionally-specific WM integrity was investigated using voxel-based statistics of whole-brain FA maps and region-of-interest analysis. Each patient underwent laboratory and neuropsychological tests. Results Structural MRI revealed no lesions in twelve (HIV-MRN and unspecific mild macrostructural lesions in seven patients (HIV-MRL. Both analyses revealed widespread FA-alterations in all patients. Patients with HIV-MRL had FA-alterations primarily adjacent to the observed lesions and, whilst reduced in extent, patients with HIV-MRN also exhibited FA-alterations in similar regions. Patients with evidence of depression showed FA-increase in the ventral tegmental area, pallidum and nucleus accumbens in both hemispheres, and patients with evidence of HIV-associated neurocognitive disorder showed widespread FA-reduction. Conclusion These results show that patients with HIV-MRN have evidence of FA-alterations in similar regions that are lesioned in HIV-MRL patients, suggesting common neuropathological processes. Furthermore, they suggest a biological rather than a reactive origin of depression in HIV-patients.

  17. Differences in integrity of white matter and changes with training in spelling impaired children: a diffusion tensor imaging study.

    Science.gov (United States)

    Gebauer, D; Fink, A; Filippini, N; Johansen-Berg, H; Reishofer, G; Koschutnig, K; Kargl, R; Purgstaller, C; Fazekas, F; Enzinger, C

    2012-07-01

    While the functional correlates of spelling impairment have been rarely investigated, to our knowledge no study exists regarding the structural characteristics of spelling impairment and potential changes with interventions. Using diffusion tensor imaging at 3.0 T, we here therefore sought to investigate (a) differences between children with poor spelling abilities (training group and waiting group) and controls, and (b) the effects of a morpheme-based spelling intervention in children with poor spelling abilities on DTI parameters. A baseline comparison of white matter indices revealed significant differences between controls and spelling-impaired children, mainly located in the right hemisphere (superior corona radiata (SCR), posterior limb of internal capsule, superior longitudinal fasciculus). After 5 weeks of training, spelling ability improved in the training group, along with increases in fractional anisotropy and decreases of radial diffusivity in the right hemisphere compared to controls. In addition, significantly higher decreases of mean diffusivity in the right SCR for the spelling-impaired training group compared to the waiting group were observed. Our results suggest that spelling impairment is associated with differences in white-matter integrity in the right hemisphere. We also provide first indications that white matter changes occur during successful training, but this needs to be more specifically addressed in future research.

  18. Dark matter and cosmology

    Energy Technology Data Exchange (ETDEWEB)

    Schramm, D.N.

    1992-03-01

    The cosmological dark matter problem is reviewed. The Big Bang Nucleosynthesis constraints on the baryon density are compared with the densities implied by visible matter, dark halos, dynamics of clusters, gravitational lenses, large-scale velocity flows, and the {Omega} = 1 flatness/inflation argument. It is shown that (1) the majority of baryons are dark; and (2) non-baryonic dark matter is probably required on large scales. It is also noted that halo dark matter could be either baryonic or non-baryonic. Descrimination between ``cold`` and ``hot`` non-baryonic candidates is shown to depend on the assumed ``seeds`` that stimulate structure formation. Gaussian density fluctuations, such as those induced by quantum fluctuations, favor cold dark matter, whereas topological defects such as strings, textures or domain walls may work equally or better with hot dark matter. A possible connection between cold dark matter, globular cluster ages and the Hubble constant is mentioned. Recent large-scale structure measurements, coupled with microwave anisotropy limits, are shown to raise some questions for the previously favored density fluctuation picture. Accelerator and underground limits on dark matter candidates are also reviewed.

  19. Dark matter and cosmology

    Energy Technology Data Exchange (ETDEWEB)

    Schramm, D.N.

    1992-03-01

    The cosmological dark matter problem is reviewed. The Big Bang Nucleosynthesis constraints on the baryon density are compared with the densities implied by visible matter, dark halos, dynamics of clusters, gravitational lenses, large-scale velocity flows, and the {Omega} = 1 flatness/inflation argument. It is shown that (1) the majority of baryons are dark; and (2) non-baryonic dark matter is probably required on large scales. It is also noted that halo dark matter could be either baryonic or non-baryonic. Descrimination between cold'' and hot'' non-baryonic candidates is shown to depend on the assumed seeds'' that stimulate structure formation. Gaussian density fluctuations, such as those induced by quantum fluctuations, favor cold dark matter, whereas topological defects such as strings, textures or domain walls may work equally or better with hot dark matter. A possible connection between cold dark matter, globular cluster ages and the Hubble constant is mentioned. Recent large-scale structure measurements, coupled with microwave anisotropy limits, are shown to raise some questions for the previously favored density fluctuation picture. Accelerator and underground limits on dark matter candidates are also reviewed.

  20. Dark matter and cosmology

    International Nuclear Information System (INIS)

    Schramm, D.N.

    1992-03-01

    The cosmological dark matter problem is reviewed. The Big Bang Nucleosynthesis constraints on the baryon density are compared with the densities implied by visible matter, dark halos, dynamics of clusters, gravitational lenses, large-scale velocity flows, and the Ω = 1 flatness/inflation argument. It is shown that (1) the majority of baryons are dark; and (2) non-baryonic dark matter is probably required on large scales. It is also noted that halo dark matter could be either baryonic or non-baryonic. Descrimination between ''cold'' and ''hot'' non-baryonic candidates is shown to depend on the assumed ''seeds'' that stimulate structure formation. Gaussian density fluctuations, such as those induced by quantum fluctuations, favor cold dark matter, whereas topological defects such as strings, textures or domain walls may work equally or better with hot dark matter. A possible connection between cold dark matter, globular cluster ages and the Hubble constant is mentioned. Recent large-scale structure measurements, coupled with microwave anisotropy limits, are shown to raise some questions for the previously favored density fluctuation picture. Accelerator and underground limits on dark matter candidates are also reviewed

  1. Dark matter detectors

    International Nuclear Information System (INIS)

    Forster, G.

    1995-01-01

    A fundamental question of astrophysics and cosmology is the nature of dark matter. Astrophysical observations show clearly the existence of some kind of dark matter, though they cannot yet reveal its nature. Dark matter can consist of baryonic particles, or of other (known or unknown) elementary particles. Baryonic dark matter probably exists in the form of dust, gas, or small stars. Other elementary particles constituting the dark matter can possibly be measured in terrestrial experiments. Possibilities for dark matter particles are neutrinos, axions and weakly interacting massive particles (WIMPs). While a direct detection of relic neutrinos seems at the moment impossible, there are experiments looking for baryonic dark matter in the form of Massive Compact Halo Objects, and for particle dark matter in the form of axions and WIMPS. (orig.)

  2. Analyses of disruption of cerebral white matter integrity in schizophrenia with MR diffusion tensor fiber tracking method

    International Nuclear Information System (INIS)

    Yamamoto, Utako; Kobayashi, Tetsuo; Kito, Shinsuke; Koga, Yoshihiko

    2010-01-01

    We have analyzed cerebral white matter using magnetic resonance diffusion tensor imaging (MR-DTI) to measure the diffusion anisotropy of water molecules. The goal of this study is the quantitative evaluation of schizophrenia. Diffusion tensor images are acquired for patients with schizophrenia and healthy comparison subjects, group-matched for age, sex, and handedness. Fiber tracking is performed on the superior longitudinal fasciculus for the comparison between the patient and comparison groups. We have analysed and compared the cross-sectional area on the starting coronal plane and the mean and standard deviation of the fractional anisotropy and the apparent diffusion coefficient along fibers in the right and left hemispheres. In the right hemisphere, the cross-sectional areas in patient group are significantly smaller than those in the comparison group. Furthermore, in the comparison group, the cross-sectional areas in the right hemisphere are significantly larger than those in the left hemisphere, whereas there is no significant difference in the patient group. These results suggest that we may evaluate the disruption in white matter integrity in schizophrenic patients quantitatively by comparing the cross-sectional area of the superior longitudinal fasciculus in the right and left hemispheres. (author)

  3. Voxel-based analyses of gray/white matter volume and diffusion tensor data in major depression. Presidential award proceedings

    International Nuclear Information System (INIS)

    Abe, Osamu; Yamasue, Hidenori; Kasai, Kiyoto

    2008-01-01

    Previous neuroimaging studies have revealed that frontolimbic dysfunction may contribute to the pathophysiology of major depressive disorder. We used voxel-based analysis to simultaneously elucidate regional changes in gray/white matter volume, mean diffusivity (MD), and fractional anisotropy (FA) in the central nervous system of patients with unipolar major depression. We studied 21 right-handed patients and 42 age- and gender-matched right-handed normal subjects without central nervous system disorders. All image processing and statistical analyses were performed using SPM5 software. Local areas showing significant gray matter volume reduction in depressive patients compared with normal controls were observed in the right parahippocampal gyrus, hippocampus, bilateral middle frontal gyri, bilateral anterior cingulate cortices, left parietal and occipital lobes, and right superior temporal gyrus. Local areas showing increased mean diffusivity in depressive patients were observed in the bilateral parahippocampal gyri, hippocampus, pons, cerebellum, left frontal and temporal lobes, and right frontal lobe. There was no significant difference between the 2 groups for fractional anisotropy and white matter volume in the entire brain. Although there was no local area in which FA and MD were significantly correlated with disease severity, FA tended to correlate negatively with depression days (total accumulated days in depressive state) in the right anterior cingulate and the left frontal white matter (FDR-corrected P=0.055 for both areas). These results suggest that the frontolimbic neural circuit may play an important role in the neuropathology of patients with major depression. (author)

  4. Electromagnetic properties of baryons

    Energy Technology Data Exchange (ETDEWEB)

    Haupt, C.

    2006-07-01

    Static observables of bound state systems in field theoretic descriptions are usually extracted from form factors in the limit of vanishing squared four-momentum transfer of the probing exchange particle. On the other hand, static properties in nonrelativistic quantum mechanics can be formulated by means of expectation values involving essentially scalar products of wave functions. The main objective of this work is to show that a synthesis of both approaches is indeed possible - at least if certain restrictions are made to the kind of interactions between the constituents of the bound system - leading to new insights into the structure of static properties. The focus lies especially on the charge radii and magnetic moments of baryons described within a covariant constituent quark model having its field theoretic foundations in the Bethe-Salpeter equation. The current matrix element in the Breit frame between the vertex functions is derived. The charge radius and magnetic moment of a bound three-fermion system is then derived by starting from their usual definition from form factors and in case of the charge radius also from the well-known radius of a charge distribution in classical electrodynamics. In both cases the static limit at the photon point is taken analytically and subsequently the integration over the relative energy variables is done. Finally the vertex functions are replaced by Salpeter amplitudes and the expression is symmetrized over the three fermions. The final results express the charge radius and magnetic moment of the three-fermion system as expectation values with respect to Salpeter amplitudes. The numerical implementation of the analytic results is done within a covariant constituent quark model with quark confinement and a residual instanton interaction accounting for the fine structure of the observed mass spectra. The Salpeter amplitudes which where obtained by solving the Salpeter equation are used to compute the expectation values of

  5. High baryon density from relativistic heavy ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Pang, Y.; Kahana, S.H. [Brookhaven National Lab., Upton, NY (United States); Schlagel, T.J. [Brookhaven National Lab., Upton, NY (United States)]|[State Univ. of New York, Stony Brook, NY (United States)

    1993-10-01

    A quantitative model, based on hadronic physics, is developed and applied to heavy ion collisions at BNL-AGS energies. This model is in excellent agreement with observed particle spectra in heavy ion collisions using Si beams, where baryon densities of three and four times the normal nuclear matter density ({rho}{sub 0}) are reached. For Au on Au collisions, the authors predict the formation of matter at very high densities (up to 10 {rho}{sub 0}).

  6. On the baryon magnetic moments

    International Nuclear Information System (INIS)

    Ferreira, P.L.

    1976-01-01

    In the context of quark confinement ideas, the baryon magnetic moments are calculated by assuming a SU(3) breaking due to the inequalities of the quark masses (m sub(p) different m sub(n) different m lambda ). The modified SU(6) result for the ratio of the magnetic moments of the neutron and proton is obtained. The p-quark is found heavier than the n-quark by circa 15 MeV. and alternative way of evaluating the baryon magnetic moments by means of simple physical considerations based on the properties of the SU(6) baryon S-waves functions is given

  7. Chiral soliton models for baryons

    International Nuclear Information System (INIS)

    Weigel, H.

    2008-01-01

    This concise research monograph introduces and reviews the concept of chiral soliton models for baryons. In these models, baryons emerge as (topological) defects of the chiral field. The many applications shed light on a number of baryon properties, ranging from static properties via nucleon resonances and deep inelastic scattering to even heavy ion collisions. As far as possible, the theoretical investigations are confronted with experiment. Conceived to bridge the gap between advanced graduate textbooks and the research literature, this volume also features a number of appendices to help nonspecialist readers to follow in more detail some of the calculations in the main text. (orig.)

  8. Sparse and Adaptive Diffusion Dictionary (SADD) for recovering intra-voxel white matter structure.

    Science.gov (United States)

    Aranda, Ramon; Ramirez-Manzanares, Alonso; Rivera, Mariano

    2015-12-01

    On the analysis of the Diffusion-Weighted Magnetic Resonance Images, multi-compartment models overcome the limitations of the well-known Diffusion Tensor model for fitting in vivo brain axonal orientations at voxels with fiber crossings, branching, kissing or bifurcations. Some successful multi-compartment methods are based on diffusion dictionaries. The diffusion dictionary-based methods assume that the observed Magnetic Resonance signal at each voxel is a linear combination of the fixed dictionary elements (dictionary atoms). The atoms are fixed along different orientations and diffusivity profiles. In this work, we present a sparse and adaptive diffusion dictionary method based on the Diffusion Basis Functions Model to estimate in vivo brain axonal fiber populations. Our proposal overcomes the following limitations of the diffusion dictionary-based methods: the limited angular resolution and the fixed shapes for the atom set. We propose to iteratively re-estimate the orientations and the diffusivity profile of the atoms independently at each voxel by using a simplified and easier-to-solve mathematical approach. As a result, we improve the fitting of the Diffusion-Weighted Magnetic Resonance signal. The advantages with respect to the former Diffusion Basis Functions method are demonstrated on the synthetic data-set used on the 2012 HARDI Reconstruction Challenge and in vivo human data. We demonstrate that improvements obtained in the intra-voxel fiber structure estimations benefit brain research allowing to obtain better tractography estimations. Hence, these improvements result in an accurate computation of the brain connectivity patterns. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. A Voxel-Based Diffusion Tensor Imaging Study of White Matter in Bipolar Disorder

    OpenAIRE

    Mahon, Katie; Wu, Jinghui; Malhotra, Anil K.; Burdick, Katherine E.; DeRosse, Pamela; Ardekani, Babak A.; Szeszko, Philip R.

    2009-01-01

    There is evidence from post-mortem and magnetic resonance imaging studies that hyperintensities, oligodendrioglial abnormalities and gross white matter volumetric alterations play a role in the pathophysiology of bipolar disorder. There is also functional imaging evidence for a defect in frontal cortico-subcortical pathways in bipolar disorder, but the white matter comprising these pathways has not been well-investigated. Few studies have investigated white matter integrity in patients with b...

  10. Baryonic Higgs at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Duerr, Michael [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Fileviez Perez, Pavel [Case Western Reserve Univ., Cleveland, OH (United States). CERCA, Physics Dept.; Smirnov, Juri [INFN, Sezione di Firenze (Italy); Florence Univ., Sesto Fiorentino (Italy). Dept. of Physics and Astronomy

    2017-04-15

    We investigate the possible collider signatures of a new Higgs in simple extensions of the Standard Model where baryon number is a local symmetry spontaneously broken at the low scale. We refer to this new Higgs as ''Baryonic Higgs''. This Higgs has peculiar properties since it can decay into all Standard Model particles, the leptophobic gauge boson, and the vector-like quarks present in these theories to ensure anomaly cancellation. We investigate in detail the constraints from the γγ, Zγ, ZZ, and WW searches at the Large Hadron Collider, needed to find a lower bound on the scale at which baryon number is spontaneously broken. The di-photon channel turns out to be a very sensitive probe in the case of small scalar mixing and can severely constrain the baryonic scale. We also study the properties of the leptophobic gauge boson in order to understand the testability of these theories at the LHC.

  11. White matter abnormalities in major depressive disorder with melancholic and atypical features: A diffusion tensor imaging study.

    Science.gov (United States)

    Ota, Miho; Noda, Takamasa; Sato, Noriko; Hattori, Kotaro; Hori, Hiroaki; Sasayama, Daimei; Teraishi, Toshiya; Nagashima, Anna; Obu, Satoko; Higuchi, Teruhiko; Kunugi, Hiroshi

    2015-06-01

    The DSM-IV recognizes some subtypes of major depressive disorder (MDD). It is known that the effectiveness of antidepressants differs among the MDD subtypes, and thus the differentiation of the subtypes is important. However, little is known as to structural brain changes in MDD with atypical features (aMDD) in comparison with MDD with melancholic features (mMDD), which prompted us to examine possible differences in white matter integrity assessed with diffusion tensor imaging (DTI) between these two subtypes. Subjects were 21 patients with mMDD, 24 with aMDD, and 37 age- and sex-matched healthy volunteers whose DTI data were obtained by 1.5 tesla magnetic resonance imaging. We compared fractional anisotropy and mean diffusivity value derived from DTI data on a voxel-by-voxel basis among the two diagnostic groups and healthy subjects. There were significant decreases of fractional anisotropy and increases of mean diffusivity in patients with MDD compared with healthy subjects in the corpus callosum, inferior fronto-occipital fasciculus, and left superior longitudinal fasciculus. However, we detected no significant difference in any brain region between mMDD and aMDD. Our results suggest that patients with MDD had reduced white matter integrity in some regions; however, there was no major difference between aMDD and mMDD. © 2014 The Authors. Psychiatry and Clinical Neurosciences © 2014 Japanese Society of Psychiatry and Neurology.

  12. Quantification of diffusion tensor imaging in normal white matter maturation of early childhood using an automated processing pipeline

    International Nuclear Information System (INIS)

    Loh, K.B.; Ramli, N.; Tan, L.K.; Roziah, M.; Rahmat, K.; Ariffin, H.

    2012-01-01

    The degree and status of white matter myelination can be sensitively monitored using diffusion tensor imaging (DTI). This study looks at the measurement of fractional anistropy (FA) and mean diffusivity (MD) using an automated ROI with an existing DTI atlas. Anatomical MRI and structural DTI were performed cross-sectionally on 26 normal children (newborn to 48 months old), using 1.5-T MRI. The automated processing pipeline was implemented to convert diffusion-weighted images into the NIfTI format. DTI-TK software was used to register the processed images to the ICBM DTI-81 atlas, while AFNI software was used for automated atlas-based volumes of interest (VOIs) and statistical value extraction. DTI exhibited consistent grey-white matter contrast. Triphasic temporal variation of the FA and MD values was noted, with FA increasing and MD decreasing rapidly early in the first 12 months. The second phase lasted 12-24 months during which the rate of FA and MD changes was reduced. After 24 months, the FA and MD values plateaued. DTI is a superior technique to conventional MR imaging in depicting WM maturation. The use of the automated processing pipeline provides a reliable environment for quantitative analysis of high-throughput DTI data. (orig.)

  13. Quantification of diffusion tensor imaging in normal white matter maturation of early childhood using an automated processing pipeline

    Energy Technology Data Exchange (ETDEWEB)

    Loh, K.B.; Ramli, N.; Tan, L.K.; Roziah, M. [University of Malaya, Department of Biomedical Imaging, University Malaya Research Imaging Centre (UMRIC), Faculty of Medicine, Kuala Lumpur (Malaysia); Rahmat, K. [University of Malaya, Department of Biomedical Imaging, University Malaya Research Imaging Centre (UMRIC), Faculty of Medicine, Kuala Lumpur (Malaysia); University Malaya, Biomedical Imaging Department, Kuala Lumpur (Malaysia); Ariffin, H. [University of Malaya, Department of Paediatrics, Faculty of Medicine, Kuala Lumpur (Malaysia)

    2012-07-15

    The degree and status of white matter myelination can be sensitively monitored using diffusion tensor imaging (DTI). This study looks at the measurement of fractional anistropy (FA) and mean diffusivity (MD) using an automated ROI with an existing DTI atlas. Anatomical MRI and structural DTI were performed cross-sectionally on 26 normal children (newborn to 48 months old), using 1.5-T MRI. The automated processing pipeline was implemented to convert diffusion-weighted images into the NIfTI format. DTI-TK software was used to register the processed images to the ICBM DTI-81 atlas, while AFNI software was used for automated atlas-based volumes of interest (VOIs) and statistical value extraction. DTI exhibited consistent grey-white matter contrast. Triphasic temporal variation of the FA and MD values was noted, with FA increasing and MD decreasing rapidly early in the first 12 months. The second phase lasted 12-24 months during which the rate of FA and MD changes was reduced. After 24 months, the FA and MD values plateaued. DTI is a superior technique to conventional MR imaging in depicting WM maturation. The use of the automated processing pipeline provides a reliable environment for quantitative analysis of high-throughput DTI data. (orig.)

  14. Calm Multi-Baryon Operators

    Directory of Open Access Journals (Sweden)

    Berkowitz Evan

    2018-01-01

    Full Text Available There are many outstanding problems in nuclear physics which require input and guidance from lattice QCD calculations of few baryons systems. However, these calculations suffer from an exponentially bad signal-to-noise problem which has prevented a controlled extrapolation to the physical point. The variational method has been applied very successfully to two-meson systems, allowing for the extraction of the two-meson states very early in Euclidean time through the use of improved single hadron operators. The sheer numerical cost of using the same techniques in two-baryon systems has so far been prohibitive. We present an alternate strategy which offers some of the same advantages as the variational method while being significantly less numerically expensive. We first use the Matrix Prony method to form an optimal linear combination of single baryon interpolating fields generated from the same source and different sink interpolating fields. Very early in Euclidean time this optimal linear combination is numerically free of excited state contamination, so we coin it a calm baryon. This calm baryon operator is then used in the construction of the two-baryon correlation functions.To test this method, we perform calculations on the WM/JLab iso-clover gauge configurations at the SU(3 flavor symmetric point with mπ~ 800 MeV — the same configurations we have previously used for the calculation of two-nucleon correlation functions. We observe the calm baryon significantly removes the excited state contamination from the two-nucleon correlation function to as early a time as the single-nucleon is improved, provided non-local (displaced nucleon sources are used. For the local two-nucleon correlation function (where both nucleons are created from the same space-time location there is still improvement, but there is significant excited state contamination in the region the single calm baryon displays no excited state contamination.

  15. Spectroscopy of doubly heavy baryons

    International Nuclear Information System (INIS)

    Gershtein, S.S.; Kiselev, V.V.; Likhoded, A.K.; Onishchenko, A.I.

    2000-01-01

    Within a nonrelativistic quark model featuring a QCD-motivated Buchmueller-Tye potential, the mass spectra for the families of doubly heavy baryons are calculated by assuming the quark-diquark structure of the baryon wave functions and by taking into account spin-dependent splitting. Physically motivated evidence that, in the case where heavy quarks have identical flavors, quasistationary excited states may be formed in the heavy-diquark subsystem is analyzed

  16. Excitations of strange bottom baryons

    Energy Technology Data Exchange (ETDEWEB)

    Woloshyn, R.M. [TRIUMF, Vancouver, British Columbia (Canada)

    2016-09-15

    The ground-state and first-excited-state masses of Ω{sub b} and Ω{sub bb} baryons are calculated in lattice QCD using dynamical 2 + 1 flavour gauge fields. A set of baryon operators employing different combinations of smeared quark fields was used in the framework of the variational method. Results for radial excitation energies were confirmed by carrying out a supplementary multiexponential fitting analysis. Comparison is made with quark model calculations. (orig.)

  17. Three-dimensional white matter tractography by diffusion tensor imaging in ischaemic stroke involving the corticospinal tract

    International Nuclear Information System (INIS)

    Kunimatsu, A.; Aoki, S.; Masutani, Y.; Abe, O.; Mori, H.; Ohtomo, K.

    2003-01-01

    Diffusion tensor MR imaging (DTI) provides information on diffusion anisotropy, which can be expressed with three-dimensional (3D) white matter tractography. We used 3D white matter tractography to show the corticospinal tract in eight patients with acute or early subacute ischaemic stroke involving the posterior limb of the internal capsule or corona radiata and to assess involvement of the tract. Infarcts and the tract were shown simultaneously, providing information on their spatial relationships. In five of the eight patients, 3D fibre tract maps showed the corticospinal tract in close proximity to the infarct but not to pass through it. All these patients recovered well, with maximum improvement from the lowest score on manual muscle testing (MMT) up to the full score through rehabilitation. In the other three patients the corticospinal tract was shown running through the infarct; reduction in MMT did not necessarily improve favourably or last longer, other than in one patient. As 3D white matter tractography can show spatial relationships between the corticospinal tract and an infarct, it might be helpful in prognosis of gross motor function. (orig.)

  18. Three-dimensional white matter tractography by diffusion tensor imaging in ischaemic stroke involving the corticospinal tract

    Energy Technology Data Exchange (ETDEWEB)

    Kunimatsu, A.; Aoki, S.; Masutani, Y.; Abe, O.; Mori, H.; Ohtomo, K. [Department of Radiology, Graduate School of Medicine, Tokyo University, 7-3-1 Hongo, Bunkyo-ku, 113-8655, Tokyo (Japan)

    2003-08-01

    Diffusion tensor MR imaging (DTI) provides information on diffusion anisotropy, which can be expressed with three-dimensional (3D) white matter tractography. We used 3D white matter tractography to show the corticospinal tract in eight patients with acute or early subacute ischaemic stroke involving the posterior limb of the internal capsule or corona radiata and to assess involvement of the tract. Infarcts and the tract were shown simultaneously, providing information on their spatial relationships. In five of the eight patients, 3D fibre tract maps showed the corticospinal tract in close proximity to the infarct but not to pass through it. All these patients recovered well, with maximum improvement from the lowest score on manual muscle testing (MMT) up to the full score through rehabilitation. In the other three patients the corticospinal tract was shown running through the infarct; reduction in MMT did not necessarily improve favourably or last longer, other than in one patient. As 3D white matter tractography can show spatial relationships between the corticospinal tract and an infarct, it might be helpful in prognosis of gross motor function. (orig.)

  19. About dark matter search and diffuse gamma ray emission with the H.E.S.S. experiment

    International Nuclear Information System (INIS)

    Charbonnier, A.

    2010-01-01

    Very high energy gamma-ray astronomy (E ≥ 30 GeV), that allows to probe non-thermal processes in the universe, is a rather young field of research. Up to now, most of the objects that have been observed are point-like or have small spatial extensions. However, the interaction of cosmic rays with the interstellar medium is expected to give rise to a diffuse emission at these energies. A preliminary study of the detectability of this diffuse component by the H.E.S.S. telescope array is presented. The latter has been operating since 2004 and detects the Cherenkov light from atmospheric showers that are generated by very high energy photons. The standard On-O background subtraction method is investigated along with the influence of the sky background noise on the recorded event rate. A second theme covered by this thesis is that of the detectability of dark matter by the H.E.S.S. experiment. This is performed using Clumpy, a semi-analytical code developed during this thesis. The Clumpy code calculates the gamma-ray flux from dark matter annihilation from user-defined galactic structure and sub-structure distributions. The H.E.S.S. ∼15 hour long observation of the Carina dwarf spheroidal galaxy has furthermore set an upper limit at 10 -22 cm 3 s -1 for the dark matter annihilation cross section. (author)

  20. The link between the baryonic mass distribution and the rotation curve shape

    Science.gov (United States)

    Swaters, R. A.; Sancisi, R.; van der Hulst, J. M.; van Albada, T. S.

    2012-09-01

    The observed rotation curves of disc galaxies, ranging from late-type dwarf galaxies to early-type spirals, can be fitted remarkably well simply by scaling up the contributions of the stellar and H I discs. This 'baryonic scaling model' can explain the full breadth of observed rotation curves with only two free parameters. For a small fraction of galaxies, in particular early-type spiral galaxies, H I scaling appears to fail in the outer parts, possibly due to observational effects or ionization of H I. The overall success of the baryonic scaling model suggests that the well-known global coupling between the baryonic mass of a galaxy and its rotation velocity (known as the baryonic Tully-Fisher relation) applies at a more local level as well, and it seems to imply a link between the baryonic mass distribution and the distribution of total mass (including dark matter).

  1. Longitudinal diffusion tensor magnetic resonance imaging study of radiation-induced white matter damage in a rat model.

    Science.gov (United States)

    Wang, Silun; Wu, Ed X; Qiu, Deqiang; Leung, Lucullus H T; Lau, Ho-Fai; Khong, Pek-Lan

    2009-02-01

    Radiation-induced white matter (WM) damage is a major side effect of whole brain irradiation among childhood cancer survivors. We evaluate longitudinally the diffusion characteristics of the late radiation-induced WM damage in a rat model after 25 and 30 Gy irradiation to the hemibrain at 8 time points from 2 to 48 weeks postradiation. We hypothesize that diffusion tensor magnetic resonance imaging (DTI) indices including fractional anisotropy (FA), trace, axial diffusivity (lambda(//)), and radial diffusivity (lambda( perpendicular)) can accurately detect and monitor the histopathologic changes of radiation-induced WM damage, measured at the EC, and that these changes are dose and time dependent. Results showed a progressive reduction of FA, which was driven by reduction in lambda(//) from 4 to 40 weeks postradiation, and an increase in lambda( perpendicular) with return to baseline in lambda(//) at 48 weeks postradiation. Histologic evaluation of irradiated WM showed reactive astrogliosis from 4 weeks postradiation with reversal at 36 weeks, and demyelination, axonal degeneration, and necrosis at 48 weeks postradiation. Moreover, changes in lambda(//) correlated with reactive astrogliosis (P histopathologic changes of WM damage and our results support the use of DTI as a biomarker to noninvasively monitor radiation-induced WM damage.

  2. White matter abnormalities in treatment-naive adolescents at the earliest stages of Anorexia Nervosa: A diffusion tensor imaging study.

    Science.gov (United States)

    Gaudio, Santino; Quattrocchi, Carlo Cosimo; Piervincenzi, Claudia; Zobel, Bruno Beomonte; Montecchi, Francesca Romana; Dakanalis, Antonios; Riva, Giuseppe; Carducci, Filippo

    2017-08-30

    Few studies have examined white matter (WM) integrity in long-lasting Anorexia Nervosa (AN) patients using Diffusion Tensor Imaging (DTI). In this paper, we investigated WM integrity at the earliest stages of AN (i.e. less than 6 months duration). Fourteen treatment-naive female adolescents with AN restrictive type (AN-r) in its earliest stages and 15 age-matched healthy females received brain MRI. Fractional Anisotropy (FA), Axial Diffusivity (AD), Radial diffusivity (RD), and Mean Diffusivity (MD) maps were computed from DTI data using Tract-Based Spatial Statistics analysis. AN-r patients showed FA decreases compared to controls (p FWE < 0.05) mainly in left anterior and superior corona radiata and left superior longitudinal fasciculus. AN-r patients also showed decreased AD in superior longitudinal fasciculus bilaterally and left superior and anterior corona radiata, (p FWE < 0.05). No significant differences were found in RD and MD values between the two groups. FA and AD integrity appears to be specifically affected at the earliest stages of AN. Alterations in the microstructural properties of the above mentioned tracts, also involved in cognitive control and visual perception and processing, may be early mechanisms of vulnerability/resilience of WM in AN and sustain the key symptoms of AN, such as impaired cognitive flexibility and body image distortion. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

  3. Trade, Technology Diffusion and Misallocation : Trade Partner Matters (Replaces CentER DP 2011-125)

    NARCIS (Netherlands)

    Curuk, M.

    2012-01-01

    Abstract: This paper suggests that contingent on the productivity level of the trade partner; international trade may create resource misallocation in less productive countries. It theoretically shows how the interaction between technology diffusion induced by trade and cross sectoral heterogeneity

  4. Diffusion tensor imaging of brain tumours at 3 T: A potential tool for assessing White matter tract invasion?

    Energy Technology Data Exchange (ETDEWEB)

    Price, S.J.; Burnet, N.G.; Donovan, T.; Green, H.A.L.; Pena, A.; Antoun, N.M.; Pickard, J.D.; Carpenter, T.A.; Gillard, J.H. E-mail: jhg21@cam.ac.uk

    2003-06-01

    AIM: To determine whether diffusion tensor imaging (DTI) of brain tumours can demonstrate abnormalities distal to hyperintensities on T2-weighted images, and possibly relate these to tumour grade. MATERIALS AND METHODS: Twenty patients with histologically confirmed supratentorial tumours, both gliomas (high and low grade) and metastases, were imaged at 3 T using T2-weighted and DTI sequences. Regions of interest (ROI) were drawn within the tumour, in white matter at various distances from the tumour and in areas of abnormality on DTI that appeared normal on T2-weighted images. The relative anisotropy index (RAI)--a measure of white matter organization, was calculated for these ROI. RESULTS: The abnormality on DTI was larger than that seen on T2-weighted images in 10/13 patients (77%) with high-grade gliomas. New abnormalities were seen in the contralateral white matter in 4/13 (30%) of these cases. In these high-grade tumours the RAI in areas of white matter disruption with normal appearance on T2-weighted images was reduced (0.19{+-}0.04). Even excluding patients with previous radiotherapy this difference remains significant. In all non high-grade tumours (WHO grade II gliomas and metastases) the tumour extent on DTI was identical to the abnormalities shown on T2-weighted imaging and RAI measurements were not reduced (0.3{+-}0.04). CONCLUSIONS: Subtle white matter disruption can be identified using DTI in patients with high-grade gliomas. Such disruption is not identified in association with metastases or low-grade gliomas despite these tumours producing significant mass effect and oedema. We suggest the changes in DTI may be due to tumour infiltration and that the DTI may provide a useful method of detecting occult white matter invasion by gliomas.

  5. Diffusion tensor imaging of brain tumours at 3 T: A potential tool for assessing White matter tract invasion?

    International Nuclear Information System (INIS)

    Price, S.J.; Burnet, N.G.; Donovan, T.; Green, H.A.L.; Pena, A.; Antoun, N.M.; Pickard, J.D.; Carpenter, T.A.; Gillard, J.H.

    2003-01-01

    AIM: To determine whether diffusion tensor imaging (DTI) of brain tumours can demonstrate abnormalities distal to hyperintensities on T2-weighted images, and possibly relate these to tumour grade. MATERIALS AND METHODS: Twenty patients with histologically confirmed supratentorial tumours, both gliomas (high and low grade) and metastases, were imaged at 3 T using T2-weighted and DTI sequences. Regions of interest (ROI) were drawn within the tumour, in white matter at various distances from the tumour and in areas of abnormality on DTI that appeared normal on T2-weighted images. The relative anisotropy index (RAI)--a measure of white matter organization, was calculated for these ROI. RESULTS: The abnormality on DTI was larger than that seen on T2-weighted images in 10/13 patients (77%) with high-grade gliomas. New abnormalities were seen in the contralateral white matter in 4/13 (30%) of these cases. In these high-grade tumours the RAI in areas of white matter disruption with normal appearance on T2-weighted images was reduced (0.19±0.04). Even excluding patients with previous radiotherapy this difference remains significant. In all non high-grade tumours (WHO grade II gliomas and metastases) the tumour extent on DTI was identical to the abnormalities shown on T2-weighted imaging and RAI measurements were not reduced (0.3±0.04). CONCLUSIONS: Subtle white matter disruption can be identified using DTI in patients with high-grade gliomas. Such disruption is not identified in association with metastases or low-grade gliomas despite these tumours producing significant mass effect and oedema. We suggest the changes in DTI may be due to tumour infiltration and that the DTI may provide a useful method of detecting occult white matter invasion by gliomas

  6. Exploratory analysis of diffusion tensor imaging in children with attention deficit hyperactivity disorder: evidence of abnormal white matter structure.

    Science.gov (United States)

    Pastura, Giuseppe; Doering, Thomas; Gasparetto, Emerson Leandro; Mattos, Paulo; Araújo, Alexandra Prüfer

    2016-06-01

    Abnormalities in the white matter microstructure of the attentional system have been implicated in the aetiology of attention deficit hyperactivity disorder (ADHD). Diffusion tensor imaging (DTI) is a promising magnetic resonance imaging (MRI) technology that has increasingly been used in studies of white matter microstructure in the brain. The main objective of this work was to perform an exploratory analysis of white matter tracts in a sample of children with ADHD versus typically developing children (TDC). For this purpose, 13 drug-naive children with ADHD of both genders underwent MRI using DTI acquisition methodology and tract-based spatial statistics. The results were compared to those of a sample of 14 age- and gender-matched TDC. Lower fractional anisotropy was observed in the splenium of the corpus callosum, right superior longitudinal fasciculus, bilateral retrolenticular part of the internal capsule, bilateral inferior fronto-occipital fasciculus, left external capsule and posterior thalamic radiation (including right optic radiation). We conclude that white matter tracts in attentional and motor control systems exhibited signs of abnormal microstructure in this sample of drug-naive children with ADHD.

  7. The Inner Regions of Disk Galaxies: A Constant Baryonic Fraction?

    Directory of Open Access Journals (Sweden)

    Federico Lelli

    2014-07-01

    Full Text Available For disk galaxies (spirals and irregulars, the inner circular-velocity gradient dRV0 (inner steepness of the rotation curve correlates with the central surface brightness ∑*,0 with a slope of ~0.5. This implies that the central dynamical mass density scales almost linearly with the central baryonic density. Here I show that this empirical relation is consistent with a simple model where the central baryonic fraction ƒbar,0 is fixed to 1 (no dark matter and the observed scatter is due to differences in the baryonic mass-to-light ratio Mbar / LR (ranging from 1 to 3 in the R-band and in the characteristic thickness of the central stellar component Δz (ranging from 100 to 500 pc. Models with lower baryonic fractions are possible, although they require some fine-tuning in the values of Mbar/LR and Δz. Regardless of the actual value of ƒbar,0, the fact that different types of galaxies do not show strong variations in ƒbar,0 is surprising, and may represent a challenge for models of galaxy formation in a Λ Cold Dark Matter (ΛCDM cosmology.

  8. Insight into the baryon-gravity relation in galaxies

    International Nuclear Information System (INIS)

    Famaey, Benoit; Gentile, Gianfranco; Bruneton, Jean-Philippe; Zhao Hongsheng

    2007-01-01

    Observations of spiral galaxies strongly support a one-to-one analytical relation between the inferred gravity of dark matter at any radius and the enclosed baryonic mass. It is baffling that baryons manage to settle the dark matter gravitational potential in such a precise way, leaving no 'messy' fingerprints of the merging events and 'gastrophysical' feedbacks expected in the history of a galaxy in a concordance Universe. This correlation of gravity with baryonic mass can be interpreted from several nonstandard angles, especially as a modification of gravity called TeVeS, in which no galactic dark matter is needed. In this theory, the baryon-gravity relation is captured by the dieletric-like function μ of modified Newtonian dynamics (MOND), controlling the transition from 1/r 2 attraction in the strong gravity regime to 1/r attraction in the weak regime. Here, we study this μ-function in detail. We investigate the observational constraints upon it from fitting galaxy rotation curves, unveiling the degeneracy between the stellar mass-to-light ratio and the μ-function as well as the importance of the sharpness of transition from the strong to weak gravity regimes. We also numerically address the effects of nonspherical baryon geometry in the framework of nonlinear TeVeS, and exhaustively examine how the μ-function connects with the free function of that theory. In that regard, we exhibit the subtle effects and wide implications of renormalizing the gravitational constant. We finally present a discontinuity-free transition between quasistatic galaxies and the evolving Universe for the free function of TeVeS, inevitably leading to a return to 1/r 2 attraction at very low accelerations in isolated galaxies

  9. White matter microstructure predicts longitudinal social cognitive outcomes after paediatric traumatic brain injury: a diffusion tensor imaging study.

    Science.gov (United States)

    Ryan, N P; Genc, S; Beauchamp, M H; Yeates, K O; Hearps, S; Catroppa, C; Anderson, V A; Silk, T J

    2018-03-01

    Deficits in social cognition may be among the most profound and disabling sequelae of paediatric traumatic brain injury (TBI); however, the neuroanatomical correlates of longitudinal outcomes in this domain remain unexplored. This study aimed to characterize social cognitive outcomes longitudinally after paediatric TBI, and to evaluate the use of sub-acute diffusion tensor imaging (DTI) to predict these outcomes. The sample included 52 children with mild complex-severe TBI who were assessed on cognitive theory of mind (ToM), pragmatic language and affective ToM at 6- and 24-months post-injury. For comparison, 43 typically developing controls (TDCs) of similar age and sex were recruited. DTI data were acquired sub-acutely (mean = 5.5 weeks post-injury) in a subset of 65 children (TBI = 35; TDC = 30) to evaluate longitudinal prospective relationships between white matter microstructure assessed using Tract-Based Spatial Statistics and social cognitive outcomes. Whole brain voxel-wise analysis revealed significantly higher mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD) in the sub-acute TBI group compared with TDC, with differences observed predominantly in the splenium of the corpus callosum (sCC), sagittal stratum (SS), dorsal cingulum (DC), uncinate fasciculus (UF) and middle and superior cerebellar peduncles (MCP & SCP, respectively). Relative to TDCs, children with TBI showed poorer cognitive ToM, affective ToM and pragmatic language at 6-months post-insult, and those deficits were related to abnormal diffusivity of the sCC, SS, DC, UF, MCP and SCP. Moreover, children with TBI showed poorer affective ToM and pragmatic language at 24-months post-injury, and those outcomes were predicted by sub-acute alterations in diffusivity of the DC and MCP. Abnormal microstructure within frontal-temporal, limbic and cerebro-cerebellar white matter may be a risk factor for long-term social difficulties observed in children with TBI. DTI may have

  10. Perilesional and contralateral white matter evolution and integrity in patients with periventricular nodular heterotopia and epilepsy: a longitudinal diffusion tensor imaging study.

    Science.gov (United States)

    Liu, W; Yan, B; An, D; Niu, R; Tang, Y; Tong, X; Gong, Q; Zhou, D

    2017-12-01

    This study aimed to assess the evolution of perinodular and contralateral white matter abnormalities in patients with periventricular nodular heterotopia (PNH) and epilepsy. Diffusion tensor imaging (DTI) (64 directions) and 3 T structural magnetic resonance imaging were performed in 29 PNH patients (mean age 27.3 years), and 16 patients underwent a second scan (average time between the two scans 1.1 years). Fractional anisotropy and mean diffusivity were measured within the perilesional and contralateral white matter. Longitudinal analysis showed that white matter located 10 mm from the focal nodule displayed characteristics intermediate to tissue 5 mm away, and normal-appearing white matter (NAWM) also established evolution profiles of perinodular white matter in different cortical lobes. Compared to 29 age- and sex-matched healthy controls, significant decreased fractional anisotropy and elevated mean diffusivity values were observed in regions 5 and 10 mm from nodules (P < 0.01), whilst DTI metrics of the remaining NAWM did not differ significantly from controls. Additionally, normal DTI metrics were shown in the contralateral region in patients with unilateral PNH. Periventricular nodular heterotopia is associated with microstructural abnormalities within the perilesional white matter and the extent decreases with increasing distance from the nodule. In the homologous contralateral region, white matter diffusion metrics were unchanged in unilateral PNH. These findings have clinical implications with respect to the medical and surgical interventions of PNH-related epilepsy. © 2017 EAN.

  11. Phase transitions in nuclear matter

    International Nuclear Information System (INIS)

    Glendenning, N.K.

    1984-11-01

    The rather general circumstances under which a phase transition in hadronic matter at finite temperature to an abnormal phase in which baryon effective masses become small and in which copious baryon-antibaryon pairs appear is emphasized. A preview is also given of a soliton model of dense matter, in which at a density of about seven times nuclear density, matter ceases to be a color insulator and becomes increasingly color conducting. 22 references

  12. Baryon bias and structure formation in an accelerating universe

    International Nuclear Information System (INIS)

    Amendola, Luca; Tocchini-Valentini, Domenico

    2002-01-01

    In most models of dark energy the structure formation stops after the accelerated expansion begins. In contrast, we show that the coupling of dark energy to dark matter may induce the growth of perturbations even in the accelerated regime. In particular, we show that this occurs in the models proposed to solve the cosmic coincidence problem, in which the ratio of dark energy to dark matter is constant. Depending on the parameters, the growth may be much faster than in a standard matter-dominated era. Moreover, if the dark energy couples only to dark matter and not to baryons, as requested by the constraints imposed by local gravity measurements, the baryon fluctuations develop a constant, scale-independent, large-scale bias which is in principle directly observable. We find that a lower limit to the baryon bias b>0.5 requires the total effective parameter of state w e =1+p/ρ to be larger than 0.6 while a limit b>0.73 would rule out the model

  13. Tract-specific analysis of white matter pathways in healthy subjects: a pilot study using diffusion tensor MRI

    Energy Technology Data Exchange (ETDEWEB)

    Yasmin, Hasina; Abe, Osamu; Nakata, Yasuhiro; Hayashi, Naoto; Masutani, Yoshitaka; Goto, Masami; Ohtomo, Kuni [University of Tokyo, Department of Radiology, Bunkyo-ku, Tokyo (Japan); Aoki, Shigeki [Juntendo University, Department of Radiology, Bunkyo-ku, Tokyo (Japan)

    2009-12-15

    To date, very scant data is available regarding normal diffusion properties of white matter (WM) fibers. The present study aimed to initiate the establishment of a database of normal diffusion tensor metrics of cerebral WM fibers, including the uncinate fasciculus (UF), posterior cingulum (PC), fornix, and corticospinal tract (CST) for healthy adults using tract-specific analysis by diffusion tensor tractography (DTT). We also attempted to clarify whether age and laterality exerted any effects on this study group. DTT of WM fibers were generated for 100 healthy subjects, then mean diffusivity (MD) and fractional anisotropy (FA) of the tracts were measured. Pearson correlation analysis was used to evaluate age relationships. Paired t testing was used to compare hemispheric asymmetry. Interobserver correlation tests were also performed. Our results showed FA values for UF (right, 0.42 {+-} 0.03; left, 0.40{+-}0.03), PC (0.51 {+-} 0.06, 0.52 {+-} 0.06), fornix (0.37 {+-} 0.06, 0.38 {+-} 0.06), CST (0.70 {+-} 0.06, 0.69 {+-} 0.07), and MD values for UF (0.81 {+-} 0.03, 0.82 {+-} 0.04), PC (0.72 {+-} 0.03, 0.72 {+-} 0.04), fornix (1.86 {+-} 0.32, 1.94 {+-} 0.37), and CST (0.72 {+-} 0.03, 0.74 {+-} 0.04). We identified a significant positive correlation between age and MD in the right UF and bilateral fornices, and a negative correlation between age and FA in bilateral fornices. Hemispheric asymmetry was observed in FA of UF (right > left) and MD of CST (left > right). The results constitute a normative dataset for diffusion parameters of four WM tracts that can be used to identify, characterize, and establish the significance of changes in diseases affecting specific tracts. (orig.)

  14. Gamma-rays and the case for baryon symmetric big-bang cosmology

    Science.gov (United States)

    Stecker, F. W.

    1977-01-01

    The baryon symmetric big-bang cosmologies offer an explanation of the present photon-baryon ratio in the universe, the best present explanation of the diffuse gamma-ray background spectrum in the 1-200 MeV range, and a mechanism for galaxy formation. In regard to He production, evidence is discussed that nucleosynthesis of He may have taken place after the galaxies were formed.

  15. How social media matter: Repression and the diffusion of the Occupy Wall Street movement.

    Science.gov (United States)

    Suh, Chan S; Vasi, Ion Bogdan; Chang, Paul Y

    2017-07-01

    This study explores the role played by social media in reshaping the repression-mobilization relationship. Drawing on the case of the Occupy Wall Street movement, we examine the impact of Facebook and Twitter on the spatial diffusion of protests during a period of heightened state repression. Results from event history analyses suggest that the effects of repression on protest diffusion are contingent on the presence of social media accounts supporting the movement. We find that state repression at earlier protest sites encouraged activists to create Facebook and Twitter accounts in their own cities, which then served as important vehicles for the initiation of new Occupy protests. Moreover, results suggest that repression incidents can directly facilitate future protests in cities that already have Occupy Facebook accounts. This study highlights the potential of social media to both mediate and moderate the influence of repression on the diffusion of contemporary movements. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. QCD string in the baryon

    International Nuclear Information System (INIS)

    Kalashnikova, Yu.S.; Nefediev, A.V.

    1997-01-01

    The QCD-motivated constituent string model is extended to consider the baryon. The system of three quarks propagating in the confining background field is studied in the Wilson loop approach, and the effective action is obtained. The resulting Lagrangian at large interquark distances corresponds to the Mercedes Benz string configuration. Assuming the quarks to be heavy enough to allow the adiabatic separation of quark and string junction motion and using the hyperspherical expansion for the quark subsystem we write out and solve the classical equation of motion for the junction. We quantize the motion of the junction and demonstrate that the account of these modes leads to the effective swelling of baryon in comparison with standard potential picture. The effects of finite gluonic correlation length which do not affect the excited states but appear to be substantial for the baryonic ground state, reducing the swelling considerably is discussed

  17. Electromagnetic corrections to baryon masses

    International Nuclear Information System (INIS)

    Durand, Loyal; Ha, Phuoc

    2005-01-01

    We analyze the electromagnetic contributions to the octet and decuplet baryon masses using the heavy-baryon approximation in chiral effective field theory and methods we developed in earlier analyses of the baryon masses and magnetic moments. Our methods connect simply to Morpurgo's general parametrization of the electromagnetic contributions and to semirelativistic quark models. Our calculations are carried out including the one-loop mesonic corrections to the basic electromagnetic interactions, so to two loops overall. We find that to this order in the chiral loop expansion there are no three-body contributions. The Coleman-Glashow relation and other sum rules derived in quark models with only two-body terms therefore continue to hold, and violations involve at least three-loop processes and can be expected to be quite small. We present the complete formal results and some estimates of the matrix elements here. Numerical calculations will be presented separately

  18. The diffusion of buried matter and possible pollution of aquifers in presence of hydrodynamic dispersion

    International Nuclear Information System (INIS)

    Bestman, A.R.

    1990-11-01

    The problem of diffusion of buried waste in a moist soil is formulated in cylindrical coordinates and solved by means of integral transform techniques after appropriate asymptotic approximations. The model is then used to predict the possible contamination of aquifers situated at a given depth. (author). 2 refs, 2 figs

  19. White Matter Integrity in Asperger Syndrome: A Preliminary Diffusion Tensor Magnetic Resonance Imaging Study in Adults

    NARCIS (Netherlands)

    Bloemen, Oswald J. N.; Deeley, Quinton; Sundram, Fred; Daly, Eileen M.; Barker, Gareth J.; Jones, Derek K.; van Amelsvoort, Therese A. M. J.; Schmitz, Nicole; Robertson, Dene; Murphy, Kieran C.; Murphy, Declan G. M.

    2010-01-01

    Background: Autistic Spectrum Disorder (ASD), including Asperger syndrome and autism, is a highly genetic neurodevelopmental disorder. There is a consensus that ASD has a biological basis, and it has been proposed that it is a "connectivity" disorder. Diffusion Tensor Magnetic Resonance Imaging

  20. Structural changes of central white matter tracts in Kennedy's disease - a diffusion tensor imaging and voxel-based morphometry study.

    Science.gov (United States)

    Pieper, C C; Konrad, C; Sommer, J; Teismann, I; Schiffbauer, H

    2013-05-01

    Spinobulbar muscular atrophy [Kennedy's disease (KD)] is a rare X-linked neurodegenerative disorder of mainly spinal and bulbar motoneurons. Recent studies suggest a multisystem character of this disease. The aim of this study was to identify and characterize structural changes of gray (GM) and white matter (WM) in the central nervous system. Whole-brain-based voxel-based morphometry (VBM) and diffusion tensor imaging (DTI) analyses were applied to MRI data of eight genetically proven patients with KD and compared with 16 healthy age-matched controls. Diffusion tensor imaging analysis showed not only decreased fractional anisotropy (FA) values in the brainstem, but also widespread changes in central WM tracts, whereas VBM analysis of the WM showed alterations primarily in the brainstem and cerebellum. There were no changes in GM volume. The FA value decrease in the brainstem correlated with the disease duration. Diffusion tensor imaging analysis revealed subtle changes of central WM tract integrity, while GM and WM volume remained unaffected. In our patient sample, KD had more extended effects than previously reported. These changes could either be attributed primarily to neurodegeneration or reflect secondary plastic changes due to atrophy of lower motor neurons and reorganization of cortical structures. © 2012 John Wiley & Sons A/S.

  1. Multi-charge-state molecular dynamics and self-diffusion coefficient in the warm dense matter regime

    Science.gov (United States)

    Fu, Yongsheng; Hou, Yong; Kang, Dongdong; Gao, Cheng; Jin, Fengtao; Yuan, Jianmin

    2018-01-01

    We present a multi-ion molecular dynamics (MIMD) simulation and apply it to calculating the self-diffusion coefficients of ions with different charge-states in the warm dense matter (WDM) regime. First, the method is used for the self-consistent calculation of electron structures of different charge-state ions in the ion sphere, with the ion-sphere radii being determined by the plasma density and the ion charges. The ionic fraction is then obtained by solving the Saha equation, taking account of interactions among different charge-state ions in the system, and ion-ion pair potentials are computed using the modified Gordon-Kim method in the framework of temperature-dependent density functional theory on the basis of the electron structures. Finally, MIMD is used to calculate ionic self-diffusion coefficients from the velocity correlation function according to the Green-Kubo relation. A comparison with the results of the average-atom model shows that different statistical processes will influence the ionic diffusion coefficient in the WDM regime.

  2. Multilevel Deficiency of White Matter Connectivity Networks in Alzheimer's Disease: A Diffusion MRI Study with DTI and HARDI Models.

    Science.gov (United States)

    Wang, Tao; Shi, Feng; Jin, Yan; Yap, Pew-Thian; Wee, Chong-Yaw; Zhang, Jianye; Yang, Cece; Li, Xia; Xiao, Shifu; Shen, Dinggang

    2016-01-01

    Alzheimer's disease (AD) is the most common form of dementia in elderly people. It is an irreversible and progressive brain disease. In this paper, we utilized diffusion-weighted imaging (DWI) to detect abnormal topological organization of white matter (WM) structural networks. We compared the differences between WM connectivity characteristics at global, regional, and local levels in 26 patients with probable AD and 16 normal control (NC) elderly subjects, using connectivity networks constructed with the diffusion tensor imaging (DTI) model and the high angular resolution diffusion imaging (HARDI) model, respectively. At the global level, we found that the WM structural networks of both AD and NC groups had a small-world topology; however, the AD group showed a significant decrease in both global and local efficiency, but an increase in clustering coefficient and the average shortest path length. We further found that the AD patients had significantly decreased nodal efficiency at the regional level, as well as weaker connections in multiple local cortical and subcortical regions, such as precuneus, temporal lobe, hippocampus, and thalamus. The HARDI model was found to be more advantageous than the DTI model, as it was more sensitive to the deficiencies in AD at all of the three levels.

  3. Continuum-mediated dark matter–baryon scattering

    CERN Document Server

    Katz, Andrey; Sajjad, Aqil

    2016-01-01

    Many models of dark matter scattering with baryons may be treated either as a simple contact interaction or as the exchange of a light mediator particle. We study an alternative, in which a continuum of light mediator states may be exchanged. This could arise, for instance, from coupling to a sector which is approximately conformal at the relevant momentum transfer scale. In the non-relativistic effective theory of dark matter-baryon scattering, which is useful for parametrizing direct detection signals, the effect of such continuum mediators is to multiply the amplitude by a function of the momentum transfer q, which in the simplest case is just a power law. We develop the basic framework and study two examples: the case where the mediator is a scalar operator coupling to the Higgs portal (which turns out to be highly constrained) and the case of an antisymmetric tensor operator ${\\cal O}_{\\mu \

  4. Compression of dark halos by baryon infall - Self-similar solutions

    International Nuclear Information System (INIS)

    Ryden, B.S.

    1991-01-01

    The compression of dissipationless halos by dissipative baryon infall is examined through the use of self-similar models. The models are spherically symmetric, with asymptotic density profiles of given form. A fraction f of the matter consists of freely falling baryons; the remainder of the matter, consisting of dark matter with initial dispersion anisotropy beta is gravitationally compressed by the infalling baryons. Analytic results are presented in the limiting cases f = 1 and f = 0. Numerical results are given for halos with varying values of alpha, beta, and f. The compression of the dark matter is found to be adiabatic and has a Mach number less than 1 throughout the halo. 10 refs

  5. Microstructural White Matter Tissue Characteristics Are Modulated by Homocysteine: A Diffusion Tensor Imaging Study

    OpenAIRE

    Hsu, Jung-Lung; Chen, Wei-Hung; Bai, Chyi-Huey; Leu, Jyu-Gang; Hsu, Chien-Yeh; Viergever, Max A.; Leemans, Alexander

    2015-01-01

    Homocysteine level can lead to adverse effects on the brain white matter through endothelial dysfunction, microstructural inflammation, and neurotoxin effects. Despite previously observed associations between elevated homocysteine and macroscopic structural brain changes, it is still unknown whether microstructural associations of homocysteine on brain tissue properties can be observed in healthy subjects with routine MRI. To this end, we investigated potential relationships between homocyste...

  6. Clinical prediction of fall risk and white matter abnormalities: a diffusion tensor imaging study

    Science.gov (United States)

    The Tinetti scale is a simple clinical tool designed to predict risk of falling by focusing on gait and stance impairment in elderly persons. Gait impairment is also associated with white matter (WM) abnormalities. Objective: To test the hypothesis that elderly subjects at risk for falling, as deter...

  7. Characterization of urban particulate matter by diffusive gradients in thin film technique

    Czech Academy of Sciences Publication Activity Database

    Dufka, Michaela; Dočekal, Bohumil

    (2018), s. 1-8, č. článku 9698710. ISSN 2090-8865 R&D Projects: GA ČR GAP503/10/2002 Institutional support: RVO:68081715 Keywords : thin film technique * urban particulate matter * particulate air pollution Subject RIV: CB - Analytical Chemistry , Separation OBOR OECD: Analytical chemistry Impact factor: 1.801, year: 2016

  8. Characterization of urban particulate matter by diffusive gradients in thin film technique

    Czech Academy of Sciences Publication Activity Database

    Dufka, Michaela; Dočekal, Bohumil

    (2018), s. 1-8, č. článku 9698710. ISSN 2090-8865 R&D Projects: GA ČR GAP503/10/2002 Institutional support: RVO:68081715 Keywords : thin film technique * urban particulate matter * particulate air pollution Subject RIV: CB - Analytical Chemistry, Separation OBOR OECD: Analytical chemistry Impact factor: 1.801, year: 2016

  9. Dynamics of the diffusive DM-DE interaction – Dynamical system approach

    Energy Technology Data Exchange (ETDEWEB)

    Haba, Zbigniew [Institute of Theoretical Physics, University of Wroclaw, Plac Maxa Borna 9, 50-204 Wrocław (Poland); Stachowski, Aleksander; Szydłowski, Marek, E-mail: zhab@ift.uni.wroc.pl, E-mail: aleksander.stachowski@uj.edu.pl, E-mail: marek.szydlowski@uj.edu.pl [Astronomical Observatory, Jagiellonian University, Orla 171, 30-244 Krakow (Poland)

    2016-07-01

    We discuss dynamics of a model of an energy transfer between dark energy (DE) and dark matter (DM) . The energy transfer is determined by a non-conservation law resulting from a diffusion of dark matter in an environment of dark energy. The relativistic invariance defines the diffusion in a unique way. The system can contain baryonic matter and radiation which do not interact with the dark sector. We treat the Friedman equation and the conservation laws as a closed dynamical system. The dynamics of the model is examined using the dynamical systems methods for demonstration how solutions depend on initial conditions. We also fit the model parameters using astronomical observation: SNIa, H ( z ), BAO and Alcock-Paczynski test. We show that the model with diffuse DM-DE is consistent with the data.

  10. Light asymmetric dark matter from new strong dynamics

    DEFF Research Database (Denmark)

    Frandsen, Mads Toudal; Sarkar, Subir; Schmidt-Hoberg, Kai

    2011-01-01

    A ~5 GeV `dark baryon' with a cosmic asymmetry similar to that of baryons is a natural candidate for the dark matter. We study the possibility of generating such a state through dynamical electroweak symmetry breaking, and show that it can share the relic baryon asymmetry via sphaleron interactions...

  11. The question of baryon conservation

    International Nuclear Information System (INIS)

    Goldhaber, M.

    1983-01-01

    A modern version of the law of baryon conservation might read: the net number of baryons (ΣB-ΣB-bar) does not change spontaneously or in any known interactions. For a long time it was believed that protons are absolutely stable, and neutrons sufficiently strongly bound by nuclei were also considered absolutely stable. Then a few years ago the grand unified theories were proposed in which strong, weak and electromagnetic interactions are combined, leading to the possibility that protons decay. Their lifetime is predictable in some of these theories. An experiment by the Irvine-Michigan-Brookhaven Collaboration to detect proton decays is described. (UK)

  12. Baryon symmetric big bang cosmology

    International Nuclear Information System (INIS)

    Stecker, F.W.

    1978-01-01

    It is stated that the framework of baryon symmetric big bang (BSBB) cosmology offers our greatest potential for deducting the evolution of the Universe because its physical laws and processes have the minimum number of arbitrary assumptions about initial conditions in the big-bang. In addition, it offers the possibility of explaining the photon-baryon ratio in the Universe and how galaxies and galaxy clusters are formed. BSBB cosmology also provides the only acceptable explanation at present for the origin of the cosmic γ-ray background radiation. (author)

  13. Diffuse Decreased Gray Matter in Patients with Idiopathic Craniocervical Dystonia: a Voxel-Based Morphometry Study

    Directory of Open Access Journals (Sweden)

    Camila Callegari Piccinin

    2015-01-01

    Full Text Available Background: Recent studies have addressed the role of structures other than the basal ganglia in the pathophysiology of craniocervical dystonia. Neuroimaging studies have attempted to identify structural abnormalities in craniocervical dystonia but a clear pattern of alteration has not been established. We performed whole brain evaluation using voxel-based morphometry to identify patterns of gray matter changes in craniocervical dystonia.Methods: We compared 27 patients with craniocervical dystonia matched in age and gender to 54 healthy controls. Voxel-based morphometry was used to compare gray matter volumes. We created a two-sample t-test corrected for subjects’ age and we tested with a level of significance of p<0.001 and false discovery rate correction (p<0.05. Results: Voxel-based morphometry demonstrated significant reductions of gray matter using p<0.001 in the cerebellar vermis IV/V, bilaterally in the superior frontal gyrus, precuneus, anterior cingulate and paracingulate, insular cortex, lingual gyrus and calcarine fissure; in the left hemisphere in the supplemementary motor area (SMA, inferior frontal gyrus, inferior parietal gyrus, temporal pole, supramarginal gyrus, rolandic operculum , hippocampus, middle occipital gyrus, cerebellar lobules IV/V, superior and middle temporal gyri; in the right hemisphere, the middle cingulate and precentral gyrus. Our study did not report any significant result using the false discovery rate correction. We also detected correlations between gray matter volume and age, disease duration, duration of botulinum toxin treatment and the Marsden-Fahn dystonia scale scores.Conclusions: We detected large clusters of gray matter changes chiefly in structures primarily involved in sensorimotor integration, motor planning, visuospatial function and emotional processing.

  14. Improving the realism of white matter numerical phantoms: a step towards a better understanding of the influence of structural disorders in diffusion MRI

    Science.gov (United States)

    Ginsburger, Kévin; Poupon, Fabrice; Beaujoin, Justine; Estournet, Delphine; Matuschke, Felix; Mangin, Jean-François; Axer, Markus; Poupon, Cyril

    2018-02-01

    White matter is composed of irregularly packed axons leading to a structural disorder in the extra-axonal space. Diffusion MRI experiments using oscillating gradient spin echo sequences have shown that the diffusivity transverse to axons in this extra-axonal space is dependent on the frequency of the employed sequence. In this study, we observe the same frequency-dependence using 3D simulations of the diffusion process in disordered media. We design a novel white matter numerical phantom generation algorithm which constructs biomimicking geometric configurations with few design parameters, and enables to control the level of disorder of the generated phantoms. The influence of various geometrical parameters present in white matter, such as global angular dispersion, tortuosity, presence of Ranvier nodes, beading, on the extra-cellular perpendicular diffusivity frequency dependence was investigated by simulating the diffusion process in numerical phantoms of increasing complexity and fitting the resulting simulated diffusion MR signal attenuation with an adequate analytical model designed for trapezoidal OGSE sequences. This work suggests that angular dispersion and especially beading have non-negligible effects on this extracellular diffusion metrics that may be measured using standard OGSE DW-MRI clinical protocols.

  15. Leptogenesis and gravity: Baryon asymmetry without decays

    Directory of Open Access Journals (Sweden)

    J.I. McDonald

    2017-03-01

    Full Text Available A popular class of theories attributes the matter-antimatter asymmetry of the Universe to CP-violating decays of super-heavy BSM particles in the Early Universe. Recently, we discovered a new source of leptogenesis in these models, namely that the same Yukawa phases which provide the CP violation for decays, combined with curved-spacetime loop effects, lead to an entirely new gravitational mechanism for generating an asymmetry, driven by the expansion of the Universe and independent of the departure of the heavy particles from equilibrium. In this Letter, we build on previous work by analysing the full Boltzmann equation, exploring the full parameter space of the theory and studying the time-evolution of the asymmetry. Remarkably, we find regions of parameter space where decays play no part at all, and where the baryon asymmetry of the Universe is determined solely by gravitational effects.

  16. Leptogenesis and gravity: Baryon asymmetry without decays

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, J.I., E-mail: pymcdonald@swansea.ac.uk; Shore, G.M., E-mail: g.m.shore@swansea.ac.uk

    2017-03-10

    A popular class of theories attributes the matter-antimatter asymmetry of the Universe to CP-violating decays of super-heavy BSM particles in the Early Universe. Recently, we discovered a new source of leptogenesis in these models, namely that the same Yukawa phases which provide the CP violation for decays, combined with curved-spacetime loop effects, lead to an entirely new gravitational mechanism for generating an asymmetry, driven by the expansion of the Universe and independent of the departure of the heavy particles from equilibrium. In this Letter, we build on previous work by analysing the full Boltzmann equation, exploring the full parameter space of the theory and studying the time-evolution of the asymmetry. Remarkably, we find regions of parameter space where decays play no part at all, and where the baryon asymmetry of the Universe is determined solely by gravitational effects.

  17. Baryonic spectroscopy and its immediate future

    International Nuclear Information System (INIS)

    Dalitz, R.H.

    1975-01-01

    The quark model is reviewed briefly for baryons and the various versions of SU(6) symmetry which were proposed and used in connection with baryon spectroscopy are reviewed. A series of basic questions are reviewed which experimental work in this field should aim to settle, as a minimal program. One also heralds the beginning of a new baryon spectroscopy associated with psi physics

  18. Asynchrony of the early maturation of white matter bundles in healthy infants: Quantitative landmarks revealed noninvasively by diffusion tensor imaging

    International Nuclear Information System (INIS)

    Dubois, J.; Perrin, M.; Mangin, J.F.; Cointepas, Y.; Duchesnay, E.; Le Bihan, D.; Hertz-Pannier, L.; Dehaene-Lambertz, G.; Dubois, J.; Dehaene-Lambertz, G.; Perrin, M.; Mangin, J.F.; Cointepas, Y.; Duchesnay, E.; Le Bihan, D.; Hertz-Pannier, L.

    2008-01-01

    Normal cognitive development in infants follows a well-known temporal sequence, which is assumed to be correlated with the structural maturation of underlying functional networks. Postmortem studies and, more recently, structural MR imaging studies have described qualitatively the heterogeneous spatio-temporal progression of white matter myelination. However, in vivo quantification of the maturation phases of fiber bundles is still lacking. We used noninvasive diffusion tensor MR imaging and tractography in twenty-three 1-4-month-old healthy infants to quantify the early maturation of the main cerebral fascicles. A specific maturation model, based on the respective roles of different maturational processes on the diffusion phenomena, was designed to highlight asynchronous maturation across bundles by evaluating the time-course of mean diffusivity and anisotropy changes over the considered developmental period. Using an original approach, a progression of maturation in four relative stages was determined in each tract by estimating the maturation state and speed, from the diffusion indices over the infants group compared with an adults group on one hand, and in each tract compared with the average over bundles on the other hand. Results were coherent with, and extended previous findings in 8 of 11 bundles, showing the anterior limb of the internal capsule and cingulum as the most immature, followed by the optic radiations, arcuate and inferior longitudinal fascicles, then the spino-thalamic tract and fornix, and finally the cortico-spinal tract as the most mature bundle. Thus, this approach provides new quantitative landmarks for further noninvasive research on brain-behavior relationships during normal and abnormal development. (authors)

  19. Regional variation of white matter development in the cat brain revealed by ex vivo diffusion MR tractography.

    Science.gov (United States)

    Dai, Guangping; Das, Avilash; Hayashi, Emiko; Chen, Qin; Takahashi, Emi

    2016-11-01

    Three-dimensional reconstruction of developing fiber pathways is essential to assessing the developmental course of fiber pathways in the whole brain. We applied diffusion spectrum imaging (DSI) tractography to five juvenile ex vivo cat brains at postnatal day (P) 35, when the degree of myelination varies across brain regions. We quantified diffusion properties (fractional anisotropy [FA] and apparent diffusion coefficient [ADC]) and other measurements (number, volume, and voxel count) on reconstructed pathways for projection (cortico-spinal and thalamo-cortical), corpus callosal, limbic (cingulum and fornix), and association (cortico-cortical) pathways, and characterized regional differences in maturation patterns by assessing diffusion properties. FA values were significantly higher in cortico-cortical pathways within the right hemisphere compared to those within the left hemisphere, while the other measurements for the cortico-cortical pathways within the hemisphere did not show asymmetry. ADC values were not asymmetric in both types of pathways. Interestingly, tract count and volume were significantly larger in the left thalamo-cortical pathways compared to the right thalamo-cortical pathways. The bilateral thalamo-cortical pathways showed high FA values compared to the other fiber pathways. On the other hand, ADC values did not show any differences across pathways studied. These results demonstrate that DSI tractography successfully depicted regional variations of white matter tracts during development when myelination is incomplete. Low FA and high ADC values in the cingulum bundle suggest that the cingulum bundle is less mature than the others at this developmental stage. Copyright © 2016 ISDN. Published by Elsevier Ltd. All rights reserved.

  20. Baryonic 3P2-dominant superfluidity under combined pion condensation with Δ isobar. 1. Formulation

    International Nuclear Information System (INIS)

    Tamagaki, Ryozo

    2006-01-01

    Baryonic superfluidity is studied in the combined pion condensation with the Δ degrees of freedom. We adopt a model previously proposed, in which both condensates of the neutral and charged pions coexist without interference in neutron star matter above the nuclear density. In setting up the most probable pairing correlation in such situation, it is crucial to extract attractive effects of the baryon-baryon spin-orbit interaction playing a decisive role in realizing the superfluid at moderate high densities. To this aim, using the quasi-baryon basis having the good angular-momentum quantum number, we define the quasi-baryon pairs with the stretched two-dimensional angular momentum with m J =±2, being the sum of a spin component m s =±1 and an orbital-angular momentum m L =±1 of the quasi-baryon pairs. Pairing interaction is given in terms of the operators of these quasi-baryon pairs. This choice enables us to include the usual 3 P 2 pair as a dominant component in the quasi-baryon pairs thus defined. Then we rewrite the quasi-baryon pair operations in terms of the operators of the quasi-particles (denoted as η) describing the single-particle eigenmode in the combined pion condensation. The Bogoliubov transformation is performed according to the scheme previously developed in the study of the neutron 3 P 2 pairing, since both cases are similar in formal structure although different in physical content. Finally we obtain a coupled gap equation among three channels corresponding to three different charge states of the quasi-baryon pairs. This paper presents such a formulation. Analysis of the matrix element of the pairing interaction and numerical results of energy gaps will be reported in a succeeding paper. (author)

  1. Flux-ratio anomalies from discs and other baryonic structures in the Illustris simulation

    Science.gov (United States)

    Hsueh, Jen-Wei; Despali, Giulia; Vegetti, Simona; Xu, Dandan; Fassnacht, Christopher D.; Metcalf, R. Benton

    2018-04-01

    The flux ratios in the multiple images of gravitationally lensed quasars can provide evidence for dark matter substructure in the halo of the lensing galaxy if the flux ratios differ from those predicted by a smooth model of the lensing galaxy mass distribution. However, it is also possible that baryonic structures in the lensing galaxy, such as edge-on discs, can produce flux-ratio anomalies. In this work, we present the first statistical analysis of flux-ratio anomalies due to baryons from a numerical simulation perspective. We select galaxies with various morphological types in the Illustris simulation and ray trace through the simulated haloes, which include baryons in the main lensing galaxies but exclude any substructures, in order to explore the pure baryonic effects. Our ray-tracing results show that the baryonic components can be a major contribution to the flux-ratio anomalies in lensed quasars and that edge-on disc lenses induce the strongest anomalies. We find that the baryonic components increase the probability of finding high flux-ratio anomalies in the early-type lenses by about 8 per cent and by about 10-20 per cent in the disc lenses. The baryonic effects also induce astrometric anomalies in 13 per cent of the mock lenses. Our results indicate that the morphology of the lens galaxy becomes important in the analysis of flux-ratio anomalies when considering the effect of baryons, and that the presence of baryons may also partially explain the discrepancy between the observed (high) anomaly frequency and what is expected due to the presence of subhaloes as predicted by the cold dark matter simulations.

  2. Axion dark matter and the 21-cm signal

    OpenAIRE

    Sikivie, Pierre

    2018-01-01

    It was shown in ref. [1] that cold dark matter axions reach thermal contact with baryons, and therefore cool them, shortly after the axions thermalize among themselves and form a Bose-Einstein condensate. The recent observation by the EDGES collaboration of a baryon temperature at cosmic dawn lower than expected under "standard" assumptions is interpreted as new evidence that the dark matter is axions, at least in part. Baryon cooling by dark matter axions is found to be consistent with the o...

  3. Grey and white matter changes in children with monocular amblyopia: voxel-based morphometry and diffusion tensor imaging study.

    Science.gov (United States)

    Li, Qian; Jiang, Qinying; Guo, Mingxia; Li, Qingji; Cai, Chunquan; Yin, Xiaohui

    2013-04-01

    To investigate the potential morphological alterations of grey and white matter in monocular amblyopic children using voxel-based morphometry (VBM) and diffusion tensor imaging (DTI). A total of 20 monocular amblyopic children and 20 age-matched controls were recruited. Whole-brain MRI scans were performed after a series of ophthalmologic exams. The imaging data were processed and two-sample t-tests were employed to identify group differences in grey matter volume (GMV), white matter volume (WMV) and fractional anisotropy (FA). After image screening, there were 12 amblyopic participants and 15 normal controls qualified for the VBM analyses. For DTI analysis, 14 amblyopes and 14 controls were included. Compared to the normal controls, reduced GMVs were observed in the left inferior occipital gyrus, the bilateral parahippocampal gyrus and the left supramarginal/postcentral gyrus in the monocular amblyopic group, with the lingual gyrus presenting augmented GMV. Meanwhile, WMVs reduced in the left calcarine, the bilateral inferior frontal and the right precuneus areas, and growth in the WMVs was seen in the right cuneus, right middle occipital and left orbital frontal areas. Diminished FA values in optic radiation and increased FA in the left middle occipital area and right precuneus were detected in amblyopic patients. In monocular amblyopia, cortices related to spatial vision underwent volume loss, which provided neuroanatomical evidence of stereoscopic defects. Additionally, white matter development was also hindered due to visual defects in amblyopes. Growth in the GMVs, WMVs and FA in the occipital lobe and precuneus may reflect a compensation effect by the unaffected eye in monocular amblyopia.

  4. Super-Gaussian, super-diffusive transport of multi-mode active matter

    OpenAIRE

    Hahn, Seungsoo; Song, Sanggeun; Kim, Dae Hyun; Yang, Gil-Suk; Lee, Kang Taek; Sung, Jaeyoung

    2017-01-01

    Living cells exhibit multi-mode transport that switches between an active, self-propelled motion and a seemingly passive, random motion. Cellular decision-making over transport mode switching is a stochastic process that depends on the dynamics of the intracellular chemical network regulating the cell migration process. Here, we propose a theory and an exactly solvable model of multi-mode active matter. Our exact model study shows that the reversible transition between a passive mode and an a...

  5. On the coherent rotation of diffuse matter in numerical simulations of clusters of galaxies

    Science.gov (United States)

    Baldi, Anna Silvia; De Petris, Marco; Sembolini, Federico; Yepes, Gustavo; Lamagna, Luca; Rasia, Elena

    2017-03-01

    We present a study on the coherent rotation of the intracluster medium and dark matter components of simulated galaxy clusters extracted from a volume-limited sample of the MUSIC project. The set is re-simulated with three different recipes for the gas physics: (I) non-radiative, (II) radiative without active galactic nuclei (AGN) feedback and (III) radiative with AGN feedback. Our analysis is based on the 146 most massive clusters identified as relaxed, 57 per cent of the total sample. We classify these objects as rotating and non-rotating according to the gas spin parameter, a quantity that can be related to cluster observations. We find that 4 per cent of the relaxed sample is rotating according to our criterion. By looking at the radial profiles of their specific angular momentum vector, we find that the solid body model is not a suitable description of rotational motions. The radial profiles of the velocity of the dark matter show a prevalence of the random velocity dispersion. Instead, the intracluster medium profiles are characterized by a comparable contribution from the tangential velocity and the dispersion. In general, the dark matter component dominates the dynamics of the clusters, as suggested by the correlation between its angular momentum and the gas one, and by the lack of relevant differences among the three sets of simulations.

  6. Changes in White-Matter Connectivity in Late Second Language Learners: Evidence from Diffusion Tensor Imaging

    Directory of Open Access Journals (Sweden)

    Eleonora Rossi

    2017-11-01

    Full Text Available Morphological brain changes as a consequence of new learning have been widely established. Learning a second language (L2 is one such experience that can lead to rapid structural neural changes. However, still relatively little is known about how levels of proficiency in the L2 and the age at which the L2 is learned influence brain neuroplasticity. The goal of this study is to provide novel evidence for the effect of bilingualism on white matter structure in relatively proficient but late L2 learners who acquired the second language after early childhood. Overall, the results demonstrate a significant effect on white matter fractional anisotropy (FA as a function of L2 learning. Higher FA values were found in a broad white matter network including the anterior thalamic radiation (ATR, the inferior fronto-occipital fasciculus (IFOF, the Uncinate Fasciculus (UF, and the inferior longitudinal fasciculus (ILF. Moreover, FA values were correlated with age of L2 acquisition, suggesting that learning an L2, even past childhood, induces neural changes. Finally, these results provide some initial evidence that variability in the age of L2 acquisition has important consequences for neural plasticity.

  7. Altered white matter microstructure associated with mild and moderate depressive symptoms in young adults, a diffusion tensor imaging study.

    Science.gov (United States)

    Ghazi Sherbaf, Farzaneh; Same, Kaveh; Ashraf-Ganjouei, Amir; Aarabi, Mohammad H

    2018-05-23

    In the context of growing evidence supporting disturbed neural connectivity in the pathogenesis of depressive symptoms, we used the diffusion tensor imaging technique to investigate white matter disruptions in previously undiagnosed and hence treatment-naive young adults with mild and moderate depressive symptoms screened by Beck's Depression Inventory test compared with age-matched and sex-matched healthy controls. This is the first diffusion tensor imaging study to assess minor forms of depression. We hypothesized that subthreshold depressive symptoms share the same neural disruptions as major depressive disorder (MDD). Each group included 47 participants with a mean age of 20.1±1.1 years. The exploratory region of interest method was used to assess integrity (fractional anisotropy and mean diffusivity) in 48 regions of the brain based on Mori atlas. Data were recruited from the Southwest University Longitudinal Imaging Multimodal Brain Data Repository. The following pathways showed significant microstructural changes by means of reduced fractional anisotropy in the group with depressive symptoms compared with normal participants: pontine crossing tract; genu of the corpus callosum; posterior limb of the internal capsule (bilaterally); and anterior, posterior, and superior corona radiata (bilaterally). None of the above regions, but the middle cerebellar peduncle and the right superior fronto-occipital fasciculus were shown to differ significantly in the mean diffusivity values between the two groups. On the basis of the current results, our findings provide evidence that the white matter impairments in the interhemispheric connections and frontal-subcortical neural circuits may play a key role in the pathogenesis of depression in young adults. The similarity of neural underpinnings in MDD and minor depressive disorder in this study further proves that these two mood disorders exist in a continuum, and milder depressive symptoms can herald a major episode

  8. Baryon superfluidity and neutrino emissivity of neutron stars

    International Nuclear Information System (INIS)

    Takatsuka, Tatsuyuki; Tamagaki, Ryozo

    2004-01-01

    For neutron stars with hyperon-mixed cores, neutrino emissivity is studied using the properties of neutron star matter determined under the equation of state, which is obtained by introducing a repulsive three-body force universal for all the baryons so as to assure the maximum mass of neutron stars compatible with observations. The case without a meson condensate is treated. We choose the inputs provided by nuclear physics, with a reliable allowance. Paying attention to the density dependence of the critical temperatures of the baryon superfluids, which reflect the nature of the baryon-baryon interaction and control neutron star cooling, we show what neutrino emission processes are efficient in regions both with and without hyperon mixing. By comparing the calculated emissivities with respect to densities, we can conclude that at densities lower than about 4 times the nuclear density, the Cooper-pair process arising from the neutron 3 P 2 superfluid dominates, while at higher densities the hyperon direct Urca process dominates. For the hyperon direct Urca process to be a candidate responsible for rapid cooling compatible with observations, a moderately large energy gap of the Λ-particle 1 S 0 superfluid is required to suppress its large emissivity. The implications of these results are discussed in the relation to thermal evolution of neutron stars. (author)

  9. A BARYONIC EFFECT ON THE MERGER TIMESCALE OF GALAXY CLUSTERS

    International Nuclear Information System (INIS)

    Zhang, Congyao; Yu, Qingjuan; Lu, Youjun

    2016-01-01

    Accurate estimation of the merger timescales of galaxy clusters is important for understanding the cluster merger process and further understanding the formation and evolution of the large-scale structure of the universe. In this paper, we explore a baryonic effect on the merger timescale of galaxy clusters by using hydrodynamical simulations. We find that the baryons play an important role in accelerating the merger process. The merger timescale decreases upon increasing the gas fraction of galaxy clusters. For example, the merger timescale is shortened by a factor of up to 3 for merging clusters with gas fractions of 0.15, compared with the timescale obtained with 0 gas fractions. The baryonic effect is significant for a wide range of merger parameters and is particularly more significant for nearly head-on mergers and high merging velocities. The baryonic effect on the merger timescale of galaxy clusters is expected to have an impact on the structure formation in the universe, such as the cluster mass function and massive substructures in galaxy clusters, and a bias of “no-gas” may exist in the results obtained from the dark matter-only cosmological simulations

  10. Magnetic monopoles and baryon decay

    International Nuclear Information System (INIS)

    Pak, N.; Panagiotakopoulos, C.; Shafi, Q.

    1982-08-01

    The scattering of a non-relativistic quark from a GUT monopole is affected by the anomalous magnetic moment of the quark. In order that monopole catalysis of baryon decay can occur, it must be assumed that the anomalous magnetic moment decreases sufficiently rapidly below the QCD scale. (author)

  11. Baryon production from cluster hadronisation

    Energy Technology Data Exchange (ETDEWEB)

    Gieseke, Stefan; Kirchgaesser, Patrick [Karlsruhe Institute of Technology, Institute for Theoretical Physics, Karlsruhe (Germany); Plaetzer, Simon [University of Vienna, Particle Physics, Faculty of Physics, Vienna (Austria)

    2018-02-15

    We present an extension to the colour reconnection model in the Monte Carlo event generator Herwig to account for the production of baryons and compare it to a series of observables for soft physics. The new model is able to improve the description of charged-particle multiplicities and hadron flavour observables in pp collisions. (orig.)

  12. Predictions for Excited Strange Baryons

    Energy Technology Data Exchange (ETDEWEB)

    Fernando, Ishara P.; Goity, Jose L. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2016-04-01

    An assessment is made of predictions for excited hyperon masses which follow from flavor symmetry and consistency with a 1/N c expansion of QCD. Such predictions are based on presently established baryonic resonances. Low lying hyperon resonances which do not seem to fit into the proposed scheme are discussed.

  13. Beauty baryons: Recent CDF results

    International Nuclear Information System (INIS)

    Tseng, J.

    1996-12-01

    Using data collected between 1992 and 1995 at the Fermilab Tevatron, CDF has searched for the Λ b baryon through both semileptonic and hadronic decay channels. This presentation reviews measurements of the Λ b mass, lifetime, and production and decay rates performed with this data

  14. Current status of baryon spectroscopy

    International Nuclear Information System (INIS)

    Wali, K.C.

    1975-08-01

    In this review of baryon spectroscopy, the basic ideas of some of the current models and the experimental data for their claims to success are discussed including realistic or constituent quark models, experimental comparison, the experimental and theoretical basis for the assignments, algebraic quark models, and confinement schemes

  15. Baryon spectroscopy and SU(6)

    International Nuclear Information System (INIS)

    Litchfield, P.

    1977-09-01

    An elementary account of the SU(6) formalism for baryons is given. The assignment of the known resonances to SU(6) multiplets is discussed and an experimental scheme given for the spectrum of SU(6) x 0(2) multiplets. (author)

  16. Baryon observables and color confinement

    International Nuclear Information System (INIS)

    Jackson, A.D.

    1987-01-01

    Calculations of baryon observables within the framework of the chiral bag model are reviewed. The results of such calculations are found to be remarkably insensitive to the radius of color confinement and indicate the difficulty of finding unambiguous evidence for quarks in nuclei. 13 refs.; 5 figs

  17. Dark Galaxies and Lost Baryons (IAU S244)

    Science.gov (United States)

    Davies, Jonathan I.; Disney, Michael J.

    2008-05-01

    Preface; Conference prelims; The HI that barked in the night M. J. Disney; The detection of dark galaxies in blind HI surveys J. I. Davies; Red haloes of galaxies - reservoirs of baryonic dark matter? E. Zackrisson, N. Bergvall, C. Flynn, G. Ostlin, G. Micheva and B. Baldwell; Constraints on dark and visible mass in galaxies from strong gravitational lensing S. Dye and S. Warren; Lost baryons at low redshift S. Mathur, F. Nicastro and R. Williams; Observed properties of dark matter on small spatial scales R. Wyse and G. Gilmore; The mass distribution in spiral galaxies P. Salucci; Connecting lost baryons and dark galaxies via QSO absorption lines T. Tripp; ALFALFA: HI cosmology in the local universe R. Giovanelli; The ALFALFA search for (almost) dark galaxies across the HI mass function M. Haynes; HI clouds detected towards Virgo with the Arecibo Legacy Fast ALFA Survey B. Kent; Cosmic variance in the HI mass function S. Schneider; The Arecibo Galaxy Environments Survey - potential for finding dark galaxies and results so far R. Minchin et al.; Free-floating HI clouds in the M81 group E. Brinks, F. Walter and E. Skillman; Where are the stars in dark galaxies J. Rosenberg, J. Salzer and J. Cannon; The halo by halo missing baryon problem S. McGaugh; The local void is really empty R. Tully; Voids in the local volume: a limit on appearance of a galaxy in a dark matter halo A. Tikhonov and A. Klypin; Dim baryons in the cosmic web C. Impey; A census of baryons in galaxy clusters and groups A. Gonzalez, D. Zaritsky and A. Zabludo; Statistical properties of the intercluster light from SDSS image stacking S. Zibetti; QSO strong gravitational lensing and the detection of dark halos A. Maccio; Strong gravitational lensing: bright galaxies and lost dark-matter L. Koopmans; Mapping the distribution of luminous and dark matter in strong lensing galaxies I. Ferreras, P. Saha, L. Williams and S. Burles; Tidal debris posing as dark galaxies P. Duc, F. Bournaud and E. Brinks

  18. Dark matter implications of Fermi-LAT measurement of anisotropies in the diffuse gamma-ray background

    International Nuclear Information System (INIS)

    Gómez-Vargas, G.A.; Cuoco, A.; Linden, T.; Sánchez-Conde, M.A.; Siegal-Gaskins, J.M.; Delahaye, T.; Fornasa, M.; Komatsu, E.

    2014-01-01

    The detailed origin of the diffuse gamma-ray background is still unknown. However, the contribution of unresolved sources is expected to induce small-scale anisotropies in this emission, which may provide a way to identify and constrain the properties of its contributors. Recent studies have predicted the contributions to the angular power spectrum (APS) from extragalactic and galactic dark matter (DM) annihilation or decay. The Fermi-LAT collaboration reported detection of angular power with a significance larger than 3σ in the energy range from 1 GeV to 10 GeV on 22 months of data (Ackermann et al., 2012 [2]). For these preliminary results the already published Fermi-LAT APS measurements (Ackermann et al., 2012 [2]) are compared to the accurate predictions for DM anisotropies from state-of-the-art cosmological simulations as presented in Fornasa et al. (2013) [1] to derive constraints on different DM candidates

  19. Dark matter implications of Fermi-LAT measurement of anisotropies in the diffuse gamma-ray background

    Energy Technology Data Exchange (ETDEWEB)

    Gómez-Vargas, G.A., E-mail: germanarturo.gomez@uam.es [Departamento de Física Teórica, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid (Spain); Instituto de Física Teórica IFT-UAM/CSIC, Universidad Autónoma de Madrid, Cantoblanco, E-28049, Madrid (Spain); Istituto Nazionale di Fisica Nucleare, Sez. Roma Tor Vergata, Roma (Italy); Cuoco, A. [The Oskar Klein Centre for Cosmo Particle Physics, AlbaNova, SE-106 91 Stockholm (Sweden); Linden, T. [Department of Physics, University of California, Santa Cruz, CA 95064 (United States); Sánchez-Conde, M.A. [SLAC National Accelerator Laboratory and Kavli Institute for Particle Astrophysics and Cosmology, Menlo Park, CA 94025 (United States); Siegal-Gaskins, J.M. [California Institute of Technology, Pasadena, CA 91125 (United States); Delahaye, T. [LAPTh, Universit e de Savoie, CNRS, 9 chemin de Bellevue, BP110, F-74941 Annecy-le-Vieux Cedex (France); Institut d' Astrophysique de Paris, UMR 7095 – CNRS, Universit e Pierre and Marie Curie, 98 bis boulevard Arago, 75014 Paris (France); Instituto de Física Teórica IFT-UAM/CSIC, Universidad Autónoma de Madrid, Cantoblanco, E-28049, Madrid (Spain); Fornasa, M. [School of Physics and Astronomy, University of Nottingham, NG7 2RD Nottingham (United Kingdom); Komatsu, E. [Max-Planck-Institut fur Astrophysik, Karl-Schwarzschild Str. 1, 85741 Garching (Germany); Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), Todai Institutes for Advanced Study, the University of Tokyo, Kashiwa 277-8583 (Japan); Texas Cosmology Center and the Department of Astronomy, The University of Texas at Austin, 1 University Station, C1400, Austin, TX 78712 (United States); and others

    2014-04-01

    The detailed origin of the diffuse gamma-ray background is still unknown. However, the contribution of unresolved sources is expected to induce small-scale anisotropies in this emission, which may provide a way to identify and constrain the properties of its contributors. Recent studies have predicted the contributions to the angular power spectrum (APS) from extragalactic and galactic dark matter (DM) annihilation or decay. The Fermi-LAT collaboration reported detection of angular power with a significance larger than 3σ in the energy range from 1 GeV to 10 GeV on 22 months of data (Ackermann et al., 2012 [2]). For these preliminary results the already published Fermi-LAT APS measurements (Ackermann et al., 2012 [2]) are compared to the accurate predictions for DM anisotropies from state-of-the-art cosmological simulations as presented in Fornasa et al. (2013) [1] to derive constraints on different DM candidates.

  20. Automated segmentation of white matter fiber bundles using diffusion tensor imaging data and a new density based clustering algorithm.

    Science.gov (United States)

    Kamali, Tahereh; Stashuk, Daniel

    2016-10-01

    Robust and accurate segmentation of brain white matter (WM) fiber bundles assists in diagnosing and assessing progression or remission of neuropsychiatric diseases such as schizophrenia, autism and depression. Supervised segmentation methods are infeasible in most applications since generating gold standards is too costly. Hence, there is a growing interest in designing unsupervised methods. However, most conventional unsupervised methods require the number of clusters be known in advance which is not possible in most applications. The purpose of this study is to design an unsupervised segmentation algorithm for brain white matter fiber bundles which can automatically segment fiber bundles using intrinsic diffusion tensor imaging data information without considering any prior information or assumption about data distributions. Here, a new density based clustering algorithm called neighborhood distance entropy consistency (NDEC), is proposed which discovers natural clusters within data by simultaneously utilizing both local and global density information. The performance of NDEC is compared with other state of the art clustering algorithms including chameleon, spectral clustering, DBSCAN and k-means using Johns Hopkins University publicly available diffusion tensor imaging data. The performance of NDEC and other employed clustering algorithms were evaluated using dice ratio as an external evaluation criteria and density based clustering validation (DBCV) index as an internal evaluation metric. Across all employed clustering algorithms, NDEC obtained the highest average dice ratio (0.94) and DBCV value (0.71). NDEC can find clusters with arbitrary shapes and densities and consequently can be used for WM fiber bundle segmentation where there is no distinct boundary between various bundles. NDEC may also be used as an effective tool in other pattern recognition and medical diagnostic systems in which discovering natural clusters within data is a necessity. Copyright

  1. Tract-oriented statistical group comparison of diffusion in sheet-like white matter

    DEFF Research Database (Denmark)

    Lyksborg, Mark; Dyrby, T. B.; Sorensen, P. S.

    2013-01-01

    tube-like shapes, not always suitable for modelling the white matter tracts of the brain. The tract-oriented technique aimed at group studies, integrates the usage of multivariate features and outputs a single value of significance indicating tract-specific differences. This is in contrast to voxel...... based analysis techniques which outputs a significance per voxel basis, and requires multiple comparison correction. We demonstrate our technique by comparing a group of controls with a group of Multiple Sclerosis subjects obtaining significant differences on 11 different fascicle structures....

  2. Thermodynamic instabilities in hot and dense nuclear matter

    Directory of Open Access Journals (Sweden)

    Lavagno A.

    2016-01-01

    Full Text Available We study the presence of thermodynamic instabilities in a hot and dense nuclear medium where a nuclear phase transition can take place. Similarly to the low density nuclear liquid-gas phase transition, we show that such a phase transition is characterized by pure hadronic matter with both mechanical instability (fluctuations on the baryon density that by chemical-diffusive instability (fluctuations on the strangeness concentration. The analysis is performed by requiring the global conservation of baryon number and zero net strangeness in the framework of an effective relativistic mean field theory with the inclusion of the Δ(1232-isobars, hyperons and the lightest pseudoscalar and vector meson degrees of freedom. It turns out that in this situation hadronic phases with different values of strangeness content may coexist, altering significantly meson-antimeson ratios.

  3. How sensitive are di-leptons from ρ mesons to the high baryon density region?

    International Nuclear Information System (INIS)

    Vogel, S.; Schmidt, K.; Santini, E.; Sturm, C.; Bleicher, M.; Petersen, H.; Aichelin, J.

    2008-01-01

    We show that the measurement of dileptons might provide only a restricted view into the most dense stages of heavy-ion reactions. Thus, possible studies of meson and baryon properties at high baryon densities, as, e.g., done at the GSI High Acceptance DiElectron Spectrometer (HADES) and envisioned for the Facility for Antiproton and Ion Research (FAIR) compressed baryonic matter experiments, might observe weaker effects than currently expected in certain approaches. We argue that the strong absorption of resonances in the high-baryon-density region of the heavy-ion collision masks information from the early hot and dense phase due to a strong increase of the total decay width because of collisional broadening. To obtain additional information, we also compare the currently used approaches to extract dileptons from transport simulations, i.e., shining, only vector mesons from final baryon resonance decays and instant emission of dileptons and find a strong sensitivity on the method employed in particular at FAIR and the CERN Super Proton Synchrotron energies. It is shown explicitly that a restriction to ρ meson (and therefore dilepton) production only in final-state baryon resonance decays provide a strong bias toward rather low baryon densities. The results presented are obtained from ultrarelativistic quantum molecular dynamics v2.3 calculations using the standard setup

  4. Flavour and spin structure of linear baryons

    International Nuclear Information System (INIS)

    Kawarabayashi, K.; Kitakado, S.; Inami, T.

    1979-01-01

    Based on the string picture, a phenomenological model for baryons is constructed and their flavour symmetry, exchange degeneracy pattern and spin structure are studied. Baryons on leading trajectories are assumed to have the configuration of two quarks being attached to the ends of a linear string and the third sitting in the middle, called linear baryons. For such linear baryons, a unitarization scheme can be constructed in a manner similar to the dual unitarity scheme for mesons but without recourse to the 1/N expansion. It is found that the interchange interaction of the middle quark with one of the other two quarks at the ends of the string can give rise to a larger exchange degeneracy breaking of the baryon spectrum. With this non-planar correction, the model of linear baryons can account for the observed pattern of leading baryon states. (Auth.)

  5. Low-grade intraventricular hemorrhage disrupts cerebellar white matter in preterm infants: evidence from diffusion tensor imaging

    Energy Technology Data Exchange (ETDEWEB)

    Morita, Takashi; Morimoto, Masafumi; Hasegawa, Tatsuji; Morioka, Shigemi; Kidowaki, Satoshi; Moroto, Masaharu; Yamashita, Satoshi; Maeda, Hiroshi; Chiyonobu, Tomohiro; Tokuda, Sachiko; Hosoi, Hajime [Kyoto Prefectural University of Medicine, Department of Pediatrics, Graduate School of Medical Science, Kyoto (Japan); Yamada, Kei [Kyoto Prefectural University of Medicine, Department of Radiology, Graduate School of Medical Science, Kyoto (Japan)

    2015-05-01

    Recent diffusion tensor imaging (DTI) studies have demonstrated that leakage of hemosiderin into cerebrospinal fluid (CSF), which is caused by high-grade intraventricular hemorrhage (IVH), can affect cerebellar development in preterm born infants. However, a direct effect of low-grade IVH on cerebellar development is unknown. Thus, we evaluated the cerebellar and cerebral white matter (WM) of preterm infants with low-grade IVH. Using DTI tractography performed at term-equivalent age, we analyzed 42 infants who were born less than 30 weeks gestational age (GA) at birth (22 with low-grade IVH, 20 without). These infants were divided into two birth groups depending on GA, and we then compared the presence and absence of IVH which was diagnosed by cerebral ultrasound (CUS) within 10 days after birth or conventional magnetic resonance imaging (MRI) at term-equivalent age in each group. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) at the superior cerebellar peduncle (SCP), middle cerebellar peduncle (MCP), motor tract, and sensory tract were measured. In the SCP, preterm born infants with IVH had lower FA values compared with infants without IVH. In particular, younger preterm birth with IVH had lower FA values in the SCP and motor tract and higher ADC values in the MCP. Low-grade IVH impaired cerebellar and cerebral WM, especially in the SCP. Moreover, younger preterm infants exhibited greater disruptions to cerebellar WM and the motor tract than infants of older preterm birth. (orig.)

  6. Comparison of diffusion tensor imaging and voxel-based morphometry to detect white matter damage in Alzheimer's disease.

    Science.gov (United States)

    Yoon, Bora; Shim, Yong-S; Hong, Yun-Jeong; Koo, Bang-Bon; Kim, Yong-Duk; Lee, Kee-Ook; Yang, Dong-Won

    2011-03-15

    Regional atrophy of gray matter (GM) in Alzheimer's disease (AD) is well known; however, the relationship between macroscopic and microscopic changes of cerebral white matter (WM) is uncertain. The aim of this study was to investigate the pattern of GM, WM atrophy, and microscopic WM changes in the same individuals with AD. All subjects (10AD and 15 healthy controls [HC]) underwent a MRI scanning at 1.5 T, including a 3-dimensional volumetric scan and diffusion tensor imaging (DTI). We performed statistical parametric mapping (SPM) with DTI to evaluate the patterns of the microscopic WM changes, as well as voxel-based morphometry (VBM) for GM and WM volume changes between patients with AD and HC. GM atrophy was detected, mainly in posterior regions, and WM atrophy was similarly distributed, but less involved on VBM analysis. Unlike WM atrophy on VBM analysis, microscopic WM changes were shown in the medial frontal, orbitofrontal, splenium of the corpus callosum, and cingulum on DTI analysis with SPM. We demonstrated that the pattern of macroscopic WM atrophy was similar to GM atrophy, while microscopic WM changes had a different pattern and distribution. Our findings suggest that WM atrophy may preferentially reflect the secondary changes of GM atrophy, while microscopic WM changes start earlier in frontal areas before GM and WM atrophy can be detected macroscopically. Copyright © 2010 Elsevier B.V. All rights reserved.

  7. Big-bang nucleosynthesis and the baryon density of the universe.

    Science.gov (United States)

    Copi, C J; Schramm, D N; Turner, M S

    1995-01-13

    For almost 30 years, the predictions of big-bang nucleosynthesis have been used to test the big-bang model to within a fraction of a second of the bang. The agreement between the predicted and observed abundances of deuterium, helium-3, helium-4, and lithium-7 confirms the standard cosmology model and allows accurate determination of the baryon density, between 1.7 x 10(-31) and 4.1 x 10(-31) grams per cubic centimeter (corresponding to about 1 to 15 percent of the critical density). This measurement of the density of ordinary matter is pivotal to the establishment of two dark-matter problems: (i) most of the baryons are dark, and (ii) if the total mass density is greater than about 15 percent of the critical density, as many determinations indicate, the bulk of the dark matter must be "non-baryonic," composed of elementary particles left from the earliest moments.

  8. Baryons and the Borromeo

    International Nuclear Information System (INIS)

    Roberts, Craig D.; Segovia, Jorge

    2016-01-01

    The kernels in the tangible matter of our everyday experience are composed of light quarks. At least, they are light classically; but they don’t remain light. Dynamical effects within the Standard Model of Particle Physics change them in remarkable ways, so that in some configurations they appear nearly massless, but in others possess masses on the scale of light nuclei. Modern experiment and theory are exposing the mechanisms responsible for these remarkable transformations. The rewards are great if we can combine the emerging sketches into an accurate picture of confinement, which is such a singular feature of the Standard Model; and looming larger amongst the emerging ideas is a perspective that leads to a Borromean picture of the proton and its excited states. (author)

  9. Investigating the capability to resolve complex white matter structures with high b-value diffusion magnetic resonance imaging on the MGH-USC Connectom scanner.

    Science.gov (United States)

    Fan, Qiuyun; Nummenmaa, Aapo; Witzel, Thomas; Zanzonico, Roberta; Keil, Boris; Cauley, Stephen; Polimeni, Jonathan R; Tisdall, Dylan; Van Dijk, Koene R A; Buckner, Randy L; Wedeen, Van J; Rosen, Bruce R; Wald, Lawrence L

    2014-11-01

    One of the major goals of the NIH Blueprint Human Connectome Project was to map and quantify the white matter connections in the brain using diffusion tractography. Given the prevalence of complex white matter structures, the capability of resolving local white matter geometries with multiple crossings in the diffusion magnetic resonance imaging (dMRI) data is critical. Increasing b-value has been suggested for delineation of the finer details of the orientation distribution function (ODF). Although increased gradient strength and duration increase sensitivity to highly restricted intra-axonal water, gradient strength limitations require longer echo times (TE) to accommodate the increased diffusion encoding times needed to achieve a higher b-value, exponentially lowering the signal-to-noise ratio of the acquisition. To mitigate this effect, the MGH-USC Connectom scanner was built with 300 mT/m gradients, which can significantly reduce the TE of high b-value diffusion imaging. Here we report comparisons performed across b-values based on q-ball ODF metrics to investigate whether high b-value diffusion imaging on the Connectom scanner can improve resolving complex white matter structures. The q-ball ODF features became sharper as the b-value increased, with increased power fraction in higher order spherical harmonic series of the ODF and increased peak heights relative to the overall size of the ODF. Crossing structures were detected in an increasingly larger fraction of white matter voxels and the spatial distribution of two-way and three-way crossing structures was largely consistent with known anatomy. Results indicate that dMRI with high diffusion encoding on the Connectom system is a promising tool to better characterize, and ultimately understand, the underlying structural organization and motifs in the human brain.

  10. Effects of baryons on the statistical properties of large scale structure of the Universe

    International Nuclear Information System (INIS)

    Guillet, T.

    2010-01-01

    Observations of weak gravitational lensing will provide strong constraints on the cosmic expansion history and the growth rate of large scale structure, yielding clues to the properties and nature of dark energy. Their interpretation is impacted by baryonic physics, which are expected to modify the total matter distribution at small scales. My work has focused on determining and modeling the impact of baryons on the statistics of the large scale matter distribution in the Universe. Using numerical simulations, I have extracted the effect of baryons on the power spectrum, variance and skewness of the total density field as predicted by these simulations. I have shown that a model based on the halo model construction, featuring a concentrated central component to account for cool condensed baryons, is able to reproduce accurately, and down to very small scales, the measured amplifications of both the variance and skewness of the density field. Because of well-known issues with baryons in current cosmological simulations, I have extended the central component model to rely on as many observation-based ingredients as possible. As an application, I have studied the effect of baryons on the predictions of the upcoming Euclid weak lensing survey. During the course of this work, I have also worked at developing and extending the RAMSES code, in particular by developing a parallel self-gravity solver, which offers significant performance gains, in particular for the simulation of some astrophysical setups such as isolated galaxy or cluster simulations. (author) [fr

  11. Dence Cold Matter

    Directory of Open Access Journals (Sweden)

    Stavinskiy Alexey

    2014-04-01

    Full Text Available Possible way to create dense cold baryonic matter in the laboratory is discussed. The density of this matter is comparable or even larger than the density of neutron star core. The properties of this matter can be controlled by trigger conditions. Experimental program for the study of properties of dense cold matter for light and heavy ion collisions at initial energy range √sNN~2-3GeV is proposed..

  12. Lithium and the nature of dark matter

    International Nuclear Information System (INIS)

    Reeves, H.

    1988-01-01

    Limits on the value of critical temperature of the quark-hadron phase transition, evaluated by chiral perturbation calculations, are discussed in the frame of primordial nucleosynthesis. The yield of lithium is compatible with the Pop II data in approximately the same range as in the case of homogeneous baryonic density models. Taking into account various factors in the search for the initial abundance of the cosmological isotopes, it appears very likely that most of the baryonic matter is not luminous and that most of the dark matter is non-baryonic. However pushing all the uncertainties to their extremes, it seems also that we do not necessarily require baryonic dark matter and, we do not necessarily require non-baryonic dark matter. The uncertainty in the value of the Hubble parameter remains one of the largest source of uncertainty in this analysis

  13. Baryon number fluctuations and the phase structure in the PNJL model

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Guo-yun; Tang, Zhan-duo; Gao, Xue-yan; He, Wei-bo [Xi' an Jiaotong University, School of Science, Xi' an, Shaanxi (China)

    2018-02-15

    We investigate the kurtosis and skewness of net-baryon number fluctuations in the Polyakov loop extended Nambu-Jona-Lasinio (PNJL) model, and discuss the relations between fluctuation distributions and the phase structure of quark-gluon matter. The calculation shows that the traces of chiral and deconfinement transitions can be effectively reflected by the kurtosis and skewness of net-baryon number fluctuations not only in the critical region but also in the crossover region. The contour plot of baryon number kurtosis derived in the PNJL model can qualitatively explain the behavior of net-proton number kurtosis in the STAR beam energy scan experiments. Moreover, the three-dimensional presentations of the kurtosis and skewness in this study are helpful to understand the relations between baryon number fluctuations and QCD phase structure. (orig.)

  14. Superball dark matter

    CERN Document Server

    Kusenko, A

    1999-01-01

    Supersymmetric models predict a natural dark-matter candidate, stable baryonic Q-balls. They could be copiously produced in the early Universe as a by-product of the Affleck-Dine baryogenesis. I review the cosmological and astrophysical implications, methods of detection, and the present limits on this form of dark matter.

  15. Analysis of normal-appearing white matter of multiple sclerosis by tensor-based two-compartment model of water diffusion

    International Nuclear Information System (INIS)

    Tachibana, Yasuhiko; Obata, Takayuki; Yoshida, Mariko; Hori, Masaaki; Kamagata, Koji; Suzuki, Michimasa; Fukunaga, Issei; Kamiya, Kouhei; Aoki, Shigeki; Yokoyama, Kazumasa; Hattori, Nobutaka; Inoue, Tomio

    2015-01-01

    To compare the significance of the two-compartment model, considering diffusional anisotropy with conventional diffusion analyzing methods regarding the detection of occult changes in normal-appearing white matter (NAWM) of multiple sclerosis (MS). Diffusion-weighted images (nine b-values with six directions) were acquired from 12 healthy female volunteers (22-52 years old, median 33 years) and 13 female MS patients (24-48 years old, median 37 years). Diffusion parameters based on the two-compartment model of water diffusion considering diffusional anisotropy was calculated by a proposed method. Other parameters including diffusion tensor imaging and conventional apparent diffusion coefficient (ADC) were also obtained. They were compared statistically between the control and MS groups. Diffusion of the slow diffusion compartment in the radial direction of neuron fibers was elevated in MS patients (0.121 x 10 -3 mm 2 /s) in comparison to control (0.100 x 10 -3 mm 2 /s), the difference being significant (P = 0.001). The difference between the groups was not significant in other comparisons, including conventional ADC and fractional anisotropy (FA) of diffusion tensor imaging. The proposed method was applicable to clinically acceptable small data. The parameters obtained by this method improved the detectability of occult changes in NAWM compared to the conventional methods. (orig.)

  16. Analysis of normal-appearing white matter of multiple sclerosis by tensor-based two-compartment model of water diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Tachibana, Yasuhiko [National Institute of Radiological Sciences, Research Center for Charged Particle Therapy, Chiba (Japan); Yokohama City University Graduate School of Medicine, Department of Radiology, Yokohama (Japan); Juntendo University School of Medicine, Department of Radiology, Tokyo (Japan); Obata, Takayuki [National Institute of Radiological Sciences, Research Center for Charged Particle Therapy, Chiba (Japan); Yoshida, Mariko; Hori, Masaaki; Kamagata, Koji; Suzuki, Michimasa; Fukunaga, Issei; Kamiya, Kouhei; Aoki, Shigeki [Juntendo University School of Medicine, Department of Radiology, Tokyo (Japan); Yokoyama, Kazumasa; Hattori, Nobutaka [Juntendo University School of Medicine, Department of Neurology, Tokyo (Japan); Inoue, Tomio [Yokohama City University Graduate School of Medicine, Department of Radiology, Yokohama (Japan)

    2015-06-01

    To compare the significance of the two-compartment model, considering diffusional anisotropy with conventional diffusion analyzing methods regarding the detection of occult changes in normal-appearing white matter (NAWM) of multiple sclerosis (MS). Diffusion-weighted images (nine b-values with six directions) were acquired from 12 healthy female volunteers (22-52 years old, median 33 years) and 13 female MS patients (24-48 years old, median 37 years). Diffusion parameters based on the two-compartment model of water diffusion considering diffusional anisotropy was calculated by a proposed method. Other parameters including diffusion tensor imaging and conventional apparent diffusion coefficient (ADC) were also obtained. They were compared statistically between the control and MS groups. Diffusion of the slow diffusion compartment in the radial direction of neuron fibers was elevated in MS patients (0.121 x 10{sup -3} mm{sup 2}/s) in comparison to control (0.100 x 10{sup -3} mm{sup 2}/s), the difference being significant (P = 0.001). The difference between the groups was not significant in other comparisons, including conventional ADC and fractional anisotropy (FA) of diffusion tensor imaging. The proposed method was applicable to clinically acceptable small data. The parameters obtained by this method improved the detectability of occult changes in NAWM compared to the conventional methods. (orig.)

  17. SU(3) chiral symmetry for baryons

    International Nuclear Information System (INIS)

    Dmitrasinovic, V.

    2011-01-01

    Three-quark nucleon interpolating fields in QCD have well-defined SU L (3)xSU R (3) and U A (1) chiral transformation properties, viz. [(6,3)+(3,6)], [(3,3-bar)+(3-bar,3)], [(8,1)+(1,8)] and their 'mirror' images. It has been shown (phenomenologically) in Ref. [2] that mixing of the [(6,3)+(3,6)] chiral multiplet with one ordinary ('naive') and one 'mirror' field belonging to the [(3,3-bar)+(3-bar,3)], [(8,1)+(1,8)] multiplets can be used to fit the values of the isovector (g A (3) ) and the flavor-singlet (isoscalar) axial coupling (g A (0) ) of the nucleon and then predict the axial F and D coefficients, or vice versa, in reasonable agreement with experiment. In an attempt to derive such mixing from an effective Lagrangian, we construct all SU L (3)xSU R (3) chirally invariant non-derivative one-meson-baryon interactions and then calculate the mixing angles in terms of baryons' masses. It turns out that there are (strong) selection rules: for example, there is only one non-derivative chirally symmetric interaction between J 1/2 fields belonging to the [(6,3)+(3,6)] and the [(3,3-bar)+(3-bar,3)] chiral multiplets, that is also U A (1) symmetric. We also study the chiral interactions of the [(3,3-bar)+(3-bar,3)] and [(8,1)+(1,8)] nucleon fields. Again, there are selection rules that allow only one off-diagonal non-derivative chiral SU L (3)xSU R (3) interaction of this type, that also explicitly breaks the U A (1) symmetry. We use this interaction to calculate the corresponding mixing angles in terms of baryon masses and fit two lowest lying observed nucleon (resonance) masses, thus predicting the third (J = 1/2, I = 3/2)Δ resonance, as well as one or two flavor-singlet Λ hyperon(s), depending on the type of mixing. The effective chiral Lagrangians derived here may be applied to high density matter calculations.

  18. White matter microstructure in 22q11 deletion syndrome: a pilot diffusion tensor imaging and voxel-based morphometry study of children and adolescents

    NARCIS (Netherlands)

    Sundram, Frederick; Campbell, Linda E.; Azuma, Rayna; Daly, Eileen; Bloemen, Oswald J. N.; Barker, Gareth J.; Chitnis, Xavier; Jones, Derek K.; van Amelsvoort, Therese; Murphy, Kieran C.; Murphy, Declan G. M.

    2010-01-01

    Young people with 22q11 Deletion Syndrome (22q11DS) are at substantial risk for developing psychosis and have significant differences in white matter (WM) volume. However, there are few in vivo studies of both WM microstructural integrity (as measured using Diffusion Tensor (DT)-MRI) and WM volume

  19. Baryon structure from lattice QCD

    International Nuclear Information System (INIS)

    Alexandrou, C.

    2009-01-01

    We present recent lattice results on the baryon spectrum, nucleon electromagnetic and axial form factors, nucleon to Δ transition form factors as well as the Δ electromagnetic form factors. The masses of the low lying baryons and the nucleon form factors are calculated using two degenerate flavors of twisted mass fermions down to pion mass of about 270 MeV. We compare to the results of other collaborations. The nucleon to Δ transition and Δ form factors are calculated in a hybrid scheme, which uses staggered sea quarks and domain wall valence quarks. The dominant magnetic dipole nucleon to Δ transition form factor is also evaluated using dynamical domain wall fermions. The transverse density distributions of the Δ in the infinite momentum frame are extracted using the form factors determined from lattice QCD. (author)

  20. Baryon physics in holographic QCD

    Directory of Open Access Journals (Sweden)

    Alex Pomarol

    2009-03-01

    Full Text Available In a simple holographic model for QCD in which the Chern–Simons term is incorporated to take into account the QCD chiral anomaly, we show that baryons arise as stable solitons which are the 5D analogs of 4D skyrmions. Contrary to 4D skyrmions and previously considered holographic scenarios, these solitons have sizes larger than the inverse cut-off of the model, and therefore they are predictable within our effective field theory approach. We perform a numerical determination of several static properties of the nucleons and find a satisfactory agreement with data. We also calculate the amplitudes of “anomalous” processes induced by the Chern–Simons term in the meson sector, such as ω→πγ and ω→3π. A combined fit to baryonic and mesonic observables leads to an agreement with experiments within 16%.

  1. Exotic heavy baryons at LHC

    International Nuclear Information System (INIS)

    Biro, T.S.; Zimanyi, J.

    1993-06-01

    A heavy bottom-charm six-quark baryon is considered. A semiclassical and a Gaussian estimate show that the octet-octet bbb-ccc configuration can be favoured energetically rather than the singlet-singlet one. This result suggests that a confined bbb-ccc six-quark state may exist. Such objects may be produced in suitable amounts by heavy-ion collisions at Large Hadronic Collider energies. (R.P.) 8 refs. 1 fig

  2. Diffusion Imaging of Cerebral White Matter in Persons Who Stutter: Evidence for Network-Level Anomalies

    Directory of Open Access Journals (Sweden)

    Shanqing eCai

    2014-02-01

    Full Text Available Deficits in brain white matter have been a main focus of recent neuroimaging studies on stuttering. However, no prior study has examined brain connectivity on the global level of the cerebral cortex in persons who stutter (PWS. In the current study, we analyzed the results from probabilistic tractography between regions comprising the cortical speech network. An anatomical parcellation scheme was used to define 28 speech production-related ROIs in each hemisphere. We used network-based statistic (NBS and graph theory to analyze the connectivity patterns obtained from tractography. At the network level, the probabilistic corticocortical connectivity from the PWS group were significantly weaker that from persons with fluent speech (PFS. NBS analysis revealed significant components in the bilateral speech networks with negative correlations with stuttering severity. To facilitate comparison with previous studies, we also performed tract-based spatial statistics (TBSS and regional fractional anisotropy (FA averaging. Results from tractography, TBSS and regional FA averaging jointly highlight the importance of several regions in the left peri-Rolandic sensorimotor and premotor areas, most notably the left ventral premotor cortex and middle primary motor cortex, in the neuroanatomical basis of stuttering.

  3. Baryons in the chiral regime

    Energy Technology Data Exchange (ETDEWEB)

    Knippschild, Bastian

    2012-03-05

    Quantum Chromodynamics (QCD) is the theory of strong interactions, one of the four fundamental forces in our Universe. It describes the interaction of gluons and quarks which build up hadrons like protons and neutrons. Most of the visible matter in our universe is made of protons and neutrons. Hence, we are interested in their fundamental properties like their masses, their distribution of charge and their shape. The only known theoretical, non-perturbative and ab initio method to investigate hadron properties at low energies is lattice Quantum Chromodynamics (lattice QCD). However, up-to-date simulations (especially for baryonic quantities) do not achieve the accuracy of experiments. In fact, current simulations do not even reproduce the experimental values for the form factors. The question arises wether these deviations can be explained by systematic effects in lattice QCD simulations. This thesis is about the computation of nucleon form factors and other hadronic quantities from lattice QCD. So called Wilson fermions are used and the u- and d-quarks are treated fully dynamically. The simulations were performed using gauge ensembles with a range of lattice spacings, volumes and pion masses. First of all, the lattice spacing was set to be able to make contact between the lattice results and their experimental complement and to be able to perform a continuum extrapolation. The light quark mass has been computed and found to be m{sub ud}{sup MS}(2 GeV)=3.03(17)(38) MeV. This value is in good agreement with values from experiments and other lattice determinations. Electro-magnetic and axial form factors of the nucleon have been calculated. From these form factors the nucleon radii and the coupling constants were computed. The different ensembles enabled us to investigate systematically the dependence of these quantities on the volume, the lattice spacing and the pion mass. Finally we perform a continuum extrapolation and chiral extrapolations to the physical point

  4. Baryons in the chiral regime

    International Nuclear Information System (INIS)

    Knippschild, Bastian

    2012-01-01

    Quantum Chromodynamics (QCD) is the theory of strong interactions, one of the four fundamental forces in our Universe. It describes the interaction of gluons and quarks which build up hadrons like protons and neutrons. Most of the visible matter in our universe is made of protons and neutrons. Hence, we are interested in their fundamental properties like their masses, their distribution of charge and their shape. The only known theoretical, non-perturbative and ab initio method to investigate hadron properties at low energies is lattice Quantum Chromodynamics (lattice QCD). However, up-to-date simulations (especially for baryonic quantities) do not achieve the accuracy of experiments. In fact, current simulations do not even reproduce the experimental values for the form factors. The question arises whether these deviations can be explained by systematic effects in lattice QCD simulations. This thesis is about the computation of nucleon form factors and other hadronic quantities from lattice QCD. So called Wilson fermions are used and the u- and d-quarks are treated fully dynamically. The simulations were performed using gauge ensembles with a range of lattice spacings, volumes and pion masses. First of all, the lattice spacing was set to be able to make contact between the lattice results and their experimental complement and to be able to perform a continuum extrapolation. The light quark mass has been computed and found to be m ud MS (2 GeV)=3.03(17)(38) MeV. This value is in good agreement with values from experiments and other lattice determinations. Electro-magnetic and axial form factors of the nucleon have been calculated. From these form factors the nucleon radii and the coupling constants were computed. The different ensembles enabled us to investigate systematically the dependence of these quantities on the volume, the lattice spacing and the pion mass. Finally we perform a continuum extrapolation and chiral extrapolations to the physical point. In

  5. Collapsed Dark Matter Structures.

    Science.gov (United States)

    Buckley, Matthew R; DiFranzo, Anthony

    2018-02-02

    The distributions of dark matter and baryons in the Universe are known to be very different: The dark matter resides in extended halos, while a significant fraction of the baryons have radiated away much of their initial energy and fallen deep into the potential wells. This difference in morphology leads to the widely held conclusion that dark matter cannot cool and collapse on any scale. We revisit this assumption and show that a simple model where dark matter is charged under a "dark electromagnetism" can allow dark matter to form gravitationally collapsed objects with characteristic mass scales much smaller than that of a Milky-Way-type galaxy. Though the majority of the dark matter in spiral galaxies would remain in the halo, such a model opens the possibility that galaxies and their associated dark matter play host to a significant number of collapsed substructures. The observational signatures of such structures are not well explored but potentially interesting.

  6. Collapsed Dark Matter Structures

    Science.gov (United States)

    Buckley, Matthew R.; DiFranzo, Anthony

    2018-02-01

    The distributions of dark matter and baryons in the Universe are known to be very different: The dark matter resides in extended halos, while a significant fraction of the baryons have radiated away much of their initial energy and fallen deep into the potential wells. This difference in morphology leads to the widely held conclusion that dark matter cannot cool and collapse on any scale. We revisit this assumption and show that a simple model where dark matter is charged under a "dark electromagnetism" can allow dark matter to form gravitationally collapsed objects with characteristic mass scales much smaller than that of a Milky-Way-type galaxy. Though the majority of the dark matter in spiral galaxies would remain in the halo, such a model opens the possibility that galaxies and their associated dark matter play host to a significant number of collapsed substructures. The observational signatures of such structures are not well explored but potentially interesting.

  7. Enhancing Diffusion MRI Measures By Integrating Grey and White Matter Morphometry With Hyperbolic Wasserstein Distance

    Science.gov (United States)

    Zhang, Wen; Shi, Jie; Yu, Jun; Zhan, Liang; Thompson, Paul M.; Wang, Yalin

    2017-01-01

    In order to improve the preclinical diagnose of Alzheimer's disease (AD), there is a great deal of interest in analyzing the AD related brain structural changes with magnetic resonance image (MRI) analyses. As the major features, variation of the structural connectivity and the cortical surface morphometry provide different views of structural changes to determine whether AD is present on presymptomatic patients. However, the large scale tensor-valued information and relatively low imaging resolution in diffusion MRI (dMRI) have created huge challenges for analysis. In this paper, we propose a novel framework that improves dMRI analysis power by fusing cortical surface morphometry features from structural MRI (sMRI). We first compute the hyperbolic harmonic maps between cortical surfaces with the landmark constraints thus to precisely evaluate surface tensor-based morphometry. Meanwhile, the graph-based analysis of structural connectivity derived from dMRI is conducted. Next, we fuse these two features via the optimal mass transportation (OMT) and eventually the Wasserstein distance (WD) based single image index is computed as a potential clinical multimodality imaging score. We apply our framework to brain images of 20 AD patients and 20 matched healthy controls, randomly chosen from the Alzheimer's Disease Neuroimaging Initiative (AD-NI2) dataset. Our preliminary experimental results of group classification outperformed those of some other single dMRI-based features, such as regional hippocampal volume, mean scores of fractional anisotropy (FA) and mean axial (MD). The novel image fusion pipeline and simple imaging score of structural changes may benefit the preclinical AD and AD prevention research. PMID:28936280

  8. Radiative decays of single heavy flavour baryons

    International Nuclear Information System (INIS)

    Majethiya, Ajay; Patel, Bhavin; Vinodkumar, P.C.

    2009-01-01

    The electromagnetic transitions between (J P =(3)/(2) + ) and (J P =(1)/(2) + ) baryons are important decay modes to observe new hadronic states experimentally. For the estimation of these transitions widths, we employ a non-relativistic quark potential model description with color Coulomb plus linear confinement potential. Such a description has been employed to compute the ground-state masses and magnetic moments of the single heavy flavor baryons. The magnetic moments of the baryons are obtained using the spin-flavor structure of the constituting quark composition of the baryon. Here, we also define an effective constituent mass of the quarks (ecqm) by taking into account the binding effects of the quarks within the baryon. The radiative transition widths are computed in terms of the magnetic moments of the baryon and the photon energy. Our results are compared with other theoretical models. (orig.)

  9. Strongly baryon-dominated disk galaxies at the peak of galaxy formation ten billion years ago.

    Science.gov (United States)

    Genzel, R; Schreiber, N M Förster; Übler, H; Lang, P; Naab, T; Bender, R; Tacconi, L J; Wisnioski, E; Wuyts, S; Alexander, T; Beifiori, A; Belli, S; Brammer, G; Burkert, A; Carollo, C M; Chan, J; Davies, R; Fossati, M; Galametz, A; Genel, S; Gerhard, O; Lutz, D; Mendel, J T; Momcheva, I; Nelson, E J; Renzini, A; Saglia, R; Sternberg, A; Tacchella, S; Tadaki, K; Wilman, D

    2017-03-15

    In the cold dark matter cosmology, the baryonic components of galaxies-stars and gas-are thought to be mixed with and embedded in non-baryonic and non-relativistic dark matter, which dominates the total mass of the galaxy and its dark-matter halo. In the local (low-redshift) Universe, the mass of dark matter within a galactic disk increases with disk radius, becoming appreciable and then dominant in the outer, baryonic regions of the disks of star-forming galaxies. This results in rotation velocities of the visible matter within the disk that are constant or increasing with disk radius-a hallmark of the dark-matter model. Comparisons between the dynamical mass, inferred from these velocities in rotational equilibrium, and the sum of the stellar and cold-gas mass at the peak epoch of galaxy formation ten billion years ago, inferred from ancillary data, suggest high baryon fractions in the inner, star-forming regions of the disks. Although this implied baryon fraction may be larger than in the local Universe, the systematic uncertainties (owing to the chosen stellar initial-mass function and the calibration of gas masses) render such comparisons inconclusive in terms of the mass of dark matter. Here we report rotation curves (showing rotation velocity as a function of disk radius) for the outer disks of six massive star-forming galaxies, and find that the rotation velocities are not constant, but decrease with radius. We propose that this trend arises because of a combination of two main factors: first, a large fraction of the massive high-redshift galaxy population was strongly baryon-dominated, with dark matter playing a smaller part than in the local Universe; and second, the large velocity dispersion in high-redshift disks introduces a substantial pressure term that leads to a decrease in rotation velocity with increasing radius. The effect of both factors appears to increase with redshift. Qualitatively, the observations suggest that baryons in the early (high

  10. Determination of baryon and baryonic resonance masses from QCD sum rules. Strange baryons

    International Nuclear Information System (INIS)

    Belyaev, V.M.; Ioffe, B.L.

    1982-01-01

    The mass differences in baryonic octet Jsup(P)=1/2sup(+), decuplet Jsup(P)=3/2sup(+) and in octet Jsup(P)=3/2sup(-) are calculated basing on the QCD sum rules. The mass differences are expressed through two QCD parameters: the strange current qUark mass and the value of the quark condensate. At the properly chosen values of these parameters all of the mass differences are in a good agreement with experiment

  11. The Heavy Baryon Physics by means LEP

    International Nuclear Information System (INIS)

    Lesiak, T.

    2000-07-01

    This report describes the experimental research about the heavy baryons which were obtained in the last decade at LEP. The most important among them concern the lifetimes of beauty baryons. The methods of theoretical description of heavy hadrons together with the LEP experimental apparatus are also discussed. Heavy baryon studies are shown in a broader perspective of other LEP results: the test of the standard model and the latest measurements concerning the beauty mesons. (author)

  12. Random walk of the baryon number

    International Nuclear Information System (INIS)

    Kazaryan, A.M.; Khlebnikov, S.Y.; Shaposhnikov, M.E.

    1989-01-01

    A new approach is suggested for the anomalous nonconservation of baryon number in the electroweak theory at high temperatures. Arguments are presented in support of the idea that the baryon-number changing reactions may be viewed as random Markov processes. Making use of the general theory of Markov processes, the Fokker--Planck equation for the baryon-number distribution density is obtained and kinetic coefficients are calculated

  13. Baryon exchange effects in dual unitarisation

    International Nuclear Information System (INIS)

    Hong-Mo, C.; Tsun, T.S.

    1976-05-01

    The effects of baryon exchanges in the renormalisation of Regge trajectories are studied in the dual unitarisation scheme. The main results are that: (i) the Pomeron is boosted above α = 1, giving rising total cross sections beyond baryon-antibaryon thresholds, and (ii) the ω-trajectory remains approximately at α = .5 but acquires a sizeable admixture of the exotic antiq antiq qq state, which enhances its coupling to baryons. There are in addition a number of other interesting predictions. (author)

  14. Baryon asymmetry, inflation and squeezed states

    International Nuclear Information System (INIS)

    Bambah, Bindu A.; Chaitanya, K.V.S. Shiv; Mukku, C.

    2007-01-01

    We use the general formalism of squeezed rotated states to calculate baryon asymmetry in the wake of inflation through parametric amplification. We base our analysis on a B and CP violating Lagrangian in an isotropically expanding universe. The B and CP violating terms originate from the coupling of complex fields with non-zero baryon number to a complex background inflaton field. We show that a differential amplification of particle and antiparticle modes gives rise to baryon asymmetry

  15. Asymmetric Higgsino dark matter.

    Science.gov (United States)

    Blum, Kfir; Efrati, Aielet; Grossman, Yuval; Nir, Yosef; Riotto, Antonio

    2012-08-03

    In the supersymmetric framework, prior to the electroweak phase transition, the existence of a baryon asymmetry implies the existence of a Higgsino asymmetry. We investigate whether the Higgsino could be a viable asymmetric dark matter candidate. We find that this is indeed possible. Thus, supersymmetry can provide the observed dark matter abundance and, furthermore, relate it with the baryon asymmetry, in which case the puzzle of why the baryonic and dark matter mass densities are similar would be explained. To accomplish this task, two conditions are required. First, the gauginos, squarks, and sleptons must all be very heavy, such that the only electroweak-scale superpartners are the Higgsinos. With this spectrum, supersymmetry does not solve the fine-tuning problem. Second, the temperature of the electroweak phase transition must be low, in the (1-10) GeV range. This condition requires an extension of the minimal supersymmetric standard model.

  16. Baryon number violation and string topologies

    International Nuclear Information System (INIS)

    Sjoestrand, T.; Skands, P.Z.

    2003-01-01

    In supersymmetric scenarios with broken R-parity, baryon number violating sparticle decays become possible. In order to search for such decays, a good understanding of expected event properties is essential. We here develop a complete framework that allows detailed studies. Special attention is given to the hadronization phase, wherein the baryon number violating vertex is associated with the appearance of a junction in the colour confinement field. This allows us to tell where to look for the extra (anti)baryon directly associated with the baryon number violating decay

  17. Search for diquark clustering in baryons

    International Nuclear Information System (INIS)

    Fleck, S.; Silvestre-Brac, B.; Richard, J.M.

    1988-03-01

    In the framework of the non-relativistic quark model, we examine to which extent baryons consist of a quark bound to a localized cluster of two quarks simulating a diquark. We consider ground states and orbital excitations for various flavour combinations. A striking clustering shows up sometimes especially for the leading Regge trajectory of the nucleon and single flavoured baryons or for the ground state of baryons bearing two heavy flavours. This is, however, far from being a general pattern and there are clear differences between the three-quark description of baryons and the quark-diquark model

  18. Quark color-hyperfine interactions in baryons

    International Nuclear Information System (INIS)

    Anselmino, M.; Lichtenberg, D.B.

    1990-01-01

    We consider the contribution from the color-hyperfine interaction to the energies of groundstate hadrons, with an emphasis on baryons. We use experimental information about how the color-hyperfine term depends on flavor to make predictions about the masses of baryons containing a heavy quark. We then generalize some relations between color-hyperfine matrix elements in mesons and baryons to obtain a number of additional predictions about the masses of as-yet unobserved baryons. Most of our predictions are in the form of inequalities. (orig.)

  19. Supersymmetric dark-matter Q-balls and their interactions in matter

    International Nuclear Information System (INIS)

    Kusenko, Alexander; Loveridge, Lee C.; Shaposhnikov, Mikhail

    2005-01-01

    Supersymmetric extensions of the Standard Model contain nontopological solitons, Q-balls, which can be stable and can be a form of cosmological dark matter. Understanding the interaction of SUSY Q-balls with matter fermions is important for both astrophysical limits and laboratory searches for these dark-matter candidates. We show that a baryon scattering off a baryonic SUSY Q-ball can convert into its antiparticle with a high probability, while the baryon number of the Q-ball is increased by two units. For a SUSY Q-ball interacting with matter, this process dominates over those previously discussed in the literature

  20. Normal white matter microstructure in women long-term recovered from anorexia nervosa: A diffusion tensor imaging study.

    Science.gov (United States)

    Bang, Lasse; Rø, Øyvind; Endestad, Tor

    2018-01-01

    Studies point to white matter (WM) microstructure alterations in both adolescent and adult patients with anorexia nervosa (AN). These include reduced fractional anisotropy in several WM fiber tracts, suggesting reduced WM integrity. The extent to which these alterations are reversible with recovery from AN is unclear. There is a paucity of research investigating the presence of WM microstructure alterations in recovered AN patients, and results are inconsistent. This study aimed to investigate the presence of WM microstructure alterations in women long-term recovered from AN. Twenty-one adult women who were recovered from AN for at least 1 year were compared to 21 adult comparison women. Participants were recruited via user-organizations for eating disorders, local advertisements, and online forums. Diffusion tensor imaging was used to compare WM microstructure between groups. Correlations between WM microstructure and clinical characteristics were also explored. There were no statistically significant between-group differences in WM microstructure. These null findings remained when employing liberal alpha level thresholds. Furthermore, there were no statistically significant correlations between WM microstructure and clinical characteristics. Our findings showed normal WM microstructure in long-term recovered patients, indicating the alterations observed during the acute phase are reversible. Given the paucity of research and inconsistent findings, future studies are warranted to determine the presence of WM microstructure alterations following recovery from AN. © 2017 Wiley Periodicals, Inc.

  1. Frontal white matter alterations in short-term medicated panic disorder patients without comorbid conditions: a diffusion tensor imaging study.

    Directory of Open Access Journals (Sweden)

    Borah Kim

    Full Text Available The frontal cortex might play an important role in the fear network, and white matter (WM integrity could be related to the pathophysiology of panic disorder (PD. A few studies have investigated alterations of WM integrity in PD. The aim of this study was to determine frontal WM integrity differences between patients with PD without comorbid conditions and healthy control (HC subjects by using diffusion tensor imaging. Thirty-six patients with PD who had used medication within 1 week and 27 age- and sex-matched HC subjects participated in this study. Structural brain magnetic resonance imaging was performed on all participants. Panic Disorder Severity Scale and Beck Anxiety Inventory (BAI scores were assessed. Tract-based spatial statistics (TBSS was used for image analysis. TBSS analysis showed decreased fractional anisotropy (FA in frontal WM and WM around the frontal lobe, including the corpus callosum of both hemispheres, in patients with PD compared to HC subjects. Moreover, voxel-wise correlation analysis revealed that the BAI scores for patients with PD were positively correlated with their FA values for regions showing group differences in the FA of frontal WM of both hemispheres. Altered integrity in frontal WM of patients with PD without comorbid conditions might represent the structural pathophysiology in these patients, and these changes could be related to clinical symptoms of PD.

  2. Using CForest to Analyze Diffusion Tensor Imaging Data: A Study of White Matter Integrity in Healthy Aging.

    Science.gov (United States)

    McWhinney, Sean R; Tremblay, Antoine; Chevalier, Thérèse M; Lim, Vanessa K; Newman, Aaron J

    2016-12-01

    Healthy aging has been associated with a global reduction in white matter integrity, which is thought to reflect cognitive decline. The present study aimed to investigate this reduction over a broad range of the life span, using diffusion tensor imaging analyzed with conditional inference random forest modeling (CForest). This approach is sensitive to subtle and potentially nonlinear effects over the age continuum and was used to characterize the progression of decline in greater detail than has been possible in the past. Data were collected from 45 healthy individuals ranging in age from 19 to 67 years. Fractional anisotropy (FA) was estimated using probabilistic tractography for a number of major tracts across the brain. Age coincided with a nonlinear decrease in FA, with onset beginning at ∼30 years of age and the steepest declines occurring later in life. However, several tracts showed a transient increase before this decline. The progression of decline varied by tract, with steeper but later decline occurring in more anterior tracts. Finally, strongly right-handed individuals demonstrated relatively preserved FA until more than a decade following the onset of decline of others. These results demonstrate that using a novel, nonparametric analysis approach, previously reported reductions in FA with healthy aging were confirmed, while at the same time, new insight was provided into the onset and progression of decline, with evidence suggesting increases in integrity continuing into adulthood.

  3. White matter and schizophrenia: A meta-analysis of voxel-based morphometry and diffusion tensor imaging studies.

    Science.gov (United States)

    Vitolo, Enrico; Tatu, Mona Karina; Pignolo, Claudia; Cauda, Franco; Costa, Tommaso; Ando', Agata; Zennaro, Alessandro

    2017-12-30

    Voxel-based morphometry (VBM) and diffusion tensor imaging (DTI) are the most implemented methodologies to detect alterations of both gray and white matter (WM). However, the role of WM in mental disorders is still not well defined. We aimed at clarifying the role of WM disruption in schizophrenia and at identifying the most frequently involved brain networks. A systematic literature search was conducted to identify VBM and DTI studies focusing on WM alterations in patients with schizophrenia compared to control subjects. We selected studies reporting the coordinates of WM reductions and we performed the anatomical likelihood estimation (ALE). Moreover, we labeled the WM bundles with an anatomical atlas and compared VBM and DTI ALE-scores of each significant WM tract. A total of 59 studies were eligible for the meta-analysis. WM alterations were reported in 31 and 34 foci with VBM and DTI methods, respectively. The most occurred WM bundles in both VBM and DTI studies and largely involved in schizophrenia were long projection fibers, callosal and commissural fibers, part of motor descending fibers, and fronto-temporal-limbic pathways. The meta-analysis showed a widespread WM disruption in schizophrenia involving specific cerebral circuits instead of well-defined regions. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Diffusion Tensor Imaging Tractography Reveals Disrupted White Matter Structural Connectivity Network in Healthy Adults with Insomnia Symptoms

    Directory of Open Access Journals (Sweden)

    Feng-Mei Lu

    2017-11-01

    Full Text Available Neuroimaging studies have revealed that insomnia is characterized by aberrant neuronal connectivity in specific brain regions, but the topological disruptions in the white matter (WM structural connectivity networks remain largely unknown in insomnia. The current study uses diffusion tensor imaging (DTI tractography to construct the WM structural networks and graph theory analysis to detect alterations of the brain structural networks. The study participants comprised 30 healthy subjects with insomnia symptoms (IS and 62 healthy subjects without IS. Both the two groups showed small-world properties regarding their WM structural connectivity networks. By contrast, increased local efficiency and decreased global efficiency were identified in the IS group, indicating an insomnia-related shift in topology away from regular networks. In addition, the IS group exhibited disrupted nodal topological characteristics in regions involving the fronto-limbic and the default-mode systems. To our knowledge, this is the first study to explore the topological organization of WM structural network connectivity in insomnia. More importantly, the dysfunctions of large-scale brain systems including the fronto-limbic pathways, salience network and default-mode network in insomnia were identified, which provides new insights into the insomnia connectome. Topology-based brain network analysis thus could be a potential biomarker for IS.

  5. Selecting the best index for following the temporal evolution of apparent diffusion coefficient and diffusion anisotropy after hypoxic-ischemic white matter injury in neonates

    NARCIS (Netherlands)

    van Pul, C.; Op den Buijs, J.; Janssen, M.J.A.; Roos, F.G.; Vlaardingerbroek, M.T.; Wijn, P.F.F.

    2005-01-01

    BACKGROUND AND PURPOSE: Diffusion-weighted (DW) MR imaging is a useful technique for detecting ischemia. In adults and neonates, however, temporal changes on DW images after ischemia complicate interpretation. Our purpose was to investigate the temporal evolution of the apparent diffusion

  6. Energy loss, equilibration, and thermodynamics of a baryon rich strongly coupled quark-gluon plasma

    Energy Technology Data Exchange (ETDEWEB)

    Rougemont, Romulo [Instituto de Física, Universidade de São Paulo, Rua do Matão, 1371, Butantã, CEP 05508-090, São Paulo, SP (Brazil); Ficnar, Andrej [Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP (United Kingdom); Finazzo, Stefano I. [Instituto de Física, Universidade de São Paulo, Rua do Matão, 1371, Butantã, CEP 05508-090, São Paulo, SP (Brazil); Instituto de Física Teórica, Universidade do Estado de São Paulo, Rua Dr. Bento T. Ferraz, 271, CEP 01140-070, São Paulo, SP (Brazil); Noronha, Jorge [Instituto de Física, Universidade de São Paulo, Rua do Matão, 1371, Butantã, CEP 05508-090, São Paulo, SP (Brazil); Department of Physics, Columbia University, 538 West 120th Street, New York, NY 10027 (United States)

    2016-04-15

    Lattice data for the QCD equation of state and the baryon susceptibility near the crossover phase transition (at zero baryon density) are used to determine the input parameters of a 5-dimensional Einstein-Maxwell-Dilaton holographic model that provides a consistent holographic framework to study both equilibrium and out-of-equilibrium properties of a hot and baryon rich strongly coupled quark-gluon plasma (QGP). We compare our holographic equation of state computed at nonzero baryon chemical potential, μ{sub B}, with recent lattice calculations and find quantitative agreement for the pressure and the speed of sound for μ{sub B}≤400 MeV. This holographic model is used to obtain holographic predictions for the temperature and μ{sub B} dependence of the drag force and the Langevin diffusion coefficients associated with heavy quark jet propagation as well as the jet quenching parameter q̂ and the shooting string energy loss of light quarks in the baryon dense plasma. We find that the energy loss of heavy and light quarks generally displays a nontrivial, fast-varying behavior as a function of the temperature near the crossover. Moreover, energy loss is also found to generally increase due to nonzero baryon density effects even though this strongly coupled liquid cannot be described in terms of well defined quasiparticle excitations. Furthermore, to get a glimpse of how thermalization occurs in a hot and baryon dense QGP, we study how the lowest quasinormal mode of an external massless scalar disturbance in the bulk is affected by a nonzero baryon charge. We find that the equilibration time associated with the lowest quasinormal mode decreases in a dense medium.

  7. A galaxy lacking dark matter.

    Science.gov (United States)

    van Dokkum, Pieter; Danieli, Shany; Cohen, Yotam; Merritt, Allison; Romanowsky, Aaron J; Abraham, Roberto; Brodie, Jean; Conroy, Charlie; Lokhorst, Deborah; Mowla, Lamiya; O'Sullivan, Ewan; Zhang, Jielai

    2018-03-28

    Studies of galaxy surveys in the context of the cold dark matter paradigm have shown that the mass of the dark matter halo and the total stellar mass are coupled through a function that varies smoothly with mass. Their average ratio M halo /M stars has a minimum of about 30 for galaxies with stellar masses near that of the Milky Way (approximately 5 × 10 10 solar masses) and increases both towards lower masses and towards higher masses. The scatter in this relation is not well known; it is generally thought to be less than a factor of two for massive galaxies but much larger for dwarf galaxies. Here we report the radial velocities of ten luminous globular-cluster-like objects in the ultra-diffuse galaxy NGC1052-DF2, which has a stellar mass of approximately 2 × 10 8 solar masses. We infer that its velocity dispersion is less than 10.5 kilometres per second with 90 per cent confidence, and we determine from this that its total mass within a radius of 7.6 kiloparsecs is less than 3.4 × 10 8 solar masses. This implies that the ratio M halo /M stars is of order unity (and consistent with zero), a factor of at least 400 lower than expected. NGC1052-DF2 demonstrates that dark matter is not always coupled with baryonic matter on galactic scales.

  8. A galaxy lacking dark matter

    Science.gov (United States)

    van Dokkum, Pieter; Danieli, Shany; Cohen, Yotam; Merritt, Allison; Romanowsky, Aaron J.; Abraham, Roberto; Brodie, Jean; Conroy, Charlie; Lokhorst, Deborah; Mowla, Lamiya; O'Sullivan, Ewan; Zhang, Jielai

    2018-03-01

    Studies of galaxy surveys in the context of the cold dark matter paradigm have shown that the mass of the dark matter halo and the total stellar mass are coupled through a function that varies smoothly with mass. Their average ratio Mhalo/Mstars has a minimum of about 30 for galaxies with stellar masses near that of the Milky Way (approximately 5 × 1010 solar masses) and increases both towards lower masses and towards higher masses. The scatter in this relation is not well known; it is generally thought to be less than a factor of two for massive galaxies but much larger for dwarf galaxies. Here we report the radial velocities of ten luminous globular-cluster-like objects in the ultra-diffuse galaxy NGC1052–DF2, which has a stellar mass of approximately 2 × 108 solar masses. We infer that its velocity dispersion is less than 10.5 kilometres per second with 90 per cent confidence, and we determine from this that its total mass within a radius of 7.6 kiloparsecs is less than 3.4 × 108 solar masses. This implies that the ratio Mhalo/Mstars is of order unity (and consistent with zero), a factor of at least 400 lower than expected. NGC1052–DF2 demonstrates that dark matter is not always coupled with baryonic matter on galactic scales.

  9. Search for Nφ(1960) baryon

    International Nuclear Information System (INIS)

    Balatz, M.Ya.; Belyaev, I.M.; Dorofeev, V.A.

    1993-01-01

    In the experiments at the SPHINX facility in the 70 GeV proton beam of the IHEP accelerator the diffractive production reactions p + N → [Σ(1385) 0 K + ] + N and p + N → [Σ(1385) 0 K + ] + N + (neutral particles) were studied. In the effective mass spectra of the [Σ(1385) 0 K + ] system in these processes there were no signals from the anomalously narrow baryon state N φ (1960), which had been observed earlier in the measurement at the BIS-2 setup. 6 refs., 7 figs

  10. Search for Nφ(1960) baryon

    International Nuclear Information System (INIS)

    Balatz, M.Ya.; Belyaev, I.M.; Dorofeev, V.A.; Dzubenko, G.B.; Filimonov, I.M.; Frolov, S.V.; Golovkin, S.V.; Grishkin, Yu.L.; Gritzuk, M.V.; Kamenskii, A.D.; Kliger, G.K.; Kolganov, V.Z.; Konstantinov, A.S.; Korchagin, Yu.V.; Kozevnikov, A.P.; Kubarovskii, V.P.; Kulman, N.Yu.; Kulyavtsev, A.I.; Kurshetsov, V.F.; Kushnirenko, A.E.; Lakaev, V.S.; Landsberg, L.G.; Lomkatzi, G.S.; Molchanov, V.V.; Mukhin, V.A.; Nilov, A.P.; Novoghilov, Yu.B.; Prutskoi, V.A.; Sitnikov, A.I.; Smolyankin, V.T.; Solyanik, V.I.; Vavilov, D.V.; Victorov, V.A.; Vishnyakov, V.E.

    1994-01-01

    In the experiments at the SPHINX facility in the 70 GeV proton beam of the IHEP accelerator the diffractive production reactions p+N→[Σ(1385) 0 K + ]+N and p+N→[Σ(1385) 0 K + ]+N+ (neutral particles) were studied. In the effective mass spectra of the [Σ(1385) 0 K + ] system in these processes there were no signals from the anomalously narrow baryon state N φ (1960) which had been observed earlier in the measurement at the BIS-2 setup. (orig.)

  11. Gluon field distribution in baryons

    International Nuclear Information System (INIS)

    Bissey, F.; Cao, F-G.; Kitson, A.; Lasscock, B.G.; Leinweber, D.B.; Signal, A.I.; Williams, A.G.; Zanotti, J.M.

    2005-01-01

    Methods for revealing the distribution of gluon fields within the three-quark static-baryon potential are presented. In particular, we outline methods for studying the sensitivity of the source on the emerging vacuum response for the three-quark system. At the same time, we explore the possibility of revealing gluon-field distributions in three-quark systems in QCD without the use of gauge-dependent smoothing techniques. Renderings of flux tubes from a preliminary high-statistics study on a 12 3 x 24 lattice are presented

  12. Effects of pseudoscalar-baryon channels in the dynamically generated vector-baryon resonances

    Energy Technology Data Exchange (ETDEWEB)

    Garzon, E.J.; Oset, E. [Centro Mixto Universidad de Valencia-CSIC, Institutos de Investigacion de Paterna, Departamento de Fisica Teorica and IFIC, Valencia (Spain)

    2012-01-15

    We study the interaction of vector mesons with the octet of stable baryons in the framework of the local hidden gauge formalism using a coupled-channels unitary approach, including also the pseudoscalar-baryon channels which couple to the same quantum numbers. We examine the scattering amplitudes and their poles, which can be associated to the known J{sup P}=1/2{sup -}, 3/2{sup -} baryon resonances, and determine the role of the pseudoscalar-baryon channels, changing the width and eventually the mass of the resonances generated with only the basis of vector-baryon states. (orig.)

  13. The history of cosmic baryons: discoveries using advanced computing

    International Nuclear Information System (INIS)

    Norman, Michael L

    2005-01-01

    We live in the era of the cosmological concordance model. This refers to the precise set of cosmological parameters which describe the average composition, geometry, and expansion rate of the universe we inhabit. Due to recent observational, theoretical, and computational advances, these parameters are now known to approximately 10% accuracy, and new efforts are underway to increase precision tenfold. It is found that we live in a spatially flat, dark matter-dominated universe whose rate of expansion is accelerating due to an unseen, unknown dark energy field. Baryons-the stuff of stars, galaxies, and us-account for only 4% of the total mass-energy inventory. And yet, it is through the astronomical study of baryons that we infer the rest. In this talk I will highlight the important role advanced scientific computing has played in getting us to the concordance model, and also the computational discoveries that have been made about the history of cosmic baryons using hydrodynamical cosmological simulations. I will conclude by discussing the central role that very large scale simulations of cosmological structure formation will play in deciphering the results of upcoming dark energy surveys

  14. Diffusion tensor imaging identifies deficits in white matter microstructure in subjects with type 1 diabetes that correlate with reduced neurocognitive function.

    Science.gov (United States)

    Kodl, Christopher T; Franc, Daniel T; Rao, Jyothi P; Anderson, Fiona S; Thomas, William; Mueller, Bryon A; Lim, Kelvin O; Seaquist, Elizabeth R

    2008-11-01

    Long-standing type 1 diabetes is associated with deficits on neurocognitive testing that suggest central white matter dysfunction. This study investigated whether diffusion tensor imaging (DTI), a type of magnetic resonance imaging that measures white matter integrity quantitatively, could identify white matter microstructural deficits in patients with long-standing type 1 diabetes and whether these differences would be associated with deficits found by neurocognitive tests. Twenty-five subjects with type 1 diabetes for at least 15 years and 25 age- and sex-matched control subjects completed DTI on a 3.0 Tesla scanner and a battery of neurocognitive tests. Fractional anisotropy was calculated for the major white matter tracts of the brain. Diabetic subjects had significantly lower mean fractional anisotropy than control subjects in the posterior corona radiata and the optic radiation (P < 0.002). In type 1 diabetic subjects, reduced fractional anisotropy correlated with poorer performance on the copy portion of the Rey-Osterreith Complex Figure Drawing Test and the Grooved Peg Board Test, both of which are believed to assess white matter function. Reduced fractional anisotropy also correlated with duration of diabetes and increased A1C. A history of severe hypoglycemia did not correlate with fractional anisotropy. DTI can detect white matter microstructural deficits in subjects with long-standing type 1 diabetes. These deficits correlate with poorer performance on selected neurocognitive tests of white matter function.

  15. Diffuse alterations in grey and white matter associated with cognitive impairment in Shwachman–Diamond syndrome: Evidence from a multimodal approach

    Directory of Open Access Journals (Sweden)

    Sandra Perobelli

    2015-01-01

    Cognitive impairment in Shwachman–Diamond syndrome subjects is associated with diffuse brain anomalies in the grey matter (verbal skills with BA44 and BA20 in the right hemisphere; perceptual skills with BA5, 37, 20, 21, 42 in the left hemisphere and white matter connectivity (verbal skills with alterations in the fronto-occipital fasciculus and with the inferior-longitudinal fasciculus; perceptual skills with the arcuate fasciculus, limbic and ponto-cerebellar fasciculus; memory skills with the arcuate fasciculus; executive functions with the anterior cingulated and arcuate fasciculus.

  16. Dark matter and particle physics

    Energy Technology Data Exchange (ETDEWEB)

    Masiero, A [SISSA-ISAS, Trieste (Italy) and INFN, Sezione di Trieste (Italy); Pascoli, S [SISSA-ISAS, Trieste (Italy) and INFN, Sezione di Trieste (Italy)

    2001-11-15

    Dark matter constitutes a key-problem at the interface between Particle Physics, Astrophysics and Cosmology. Indeed, the observational facts which have been accumulated in the last years on dark matter point to the existence of an amount of non-baryonic dark matter. Since the Standard Model of Particle Physics does not possess any candidate for such non-baryonic dark matter, this problem constitutes a major indication for new Physics beyond the Standard Model. We analyze the most important candidates for non-baryonic dark matter in the context of extensions of the Standard Model (in particular supersymmetric models). The recent hints for the presence of a large amount of unclustered 'vacuum' energy (cosmological constant?) is discussed from the Astrophysical and Particle Physics perspective. (author)

  17. Warm-hot baryons comprise 5-10 per cent of filaments in the cosmic web.

    Science.gov (United States)

    Eckert, Dominique; Jauzac, Mathilde; Shan, HuanYuan; Kneib, Jean-Paul; Erben, Thomas; Israel, Holger; Jullo, Eric; Klein, Matthias; Massey, Richard; Richard, Johan; Tchernin, Céline

    2015-12-03

    Observations of the cosmic microwave background indicate that baryons account for 5 per cent of the Universe's total energy content. In the local Universe, the census of all observed baryons falls short of this estimate by a factor of two. Cosmological simulations indicate that the missing baryons have not condensed into virialized haloes, but reside throughout the filaments of the cosmic web (where matter density is larger than average) as a low-density plasma at temperatures of 10(5)-10(7) kelvin, known as the warm-hot intergalactic medium. There have been previous claims of the detection of warm-hot baryons along the line of sight to distant blazars and of hot gas between interacting clusters. These observations were, however, unable to trace the large-scale filamentary structure, or to estimate the total amount of warm-hot baryons in a representative volume of the Universe. Here we report X-ray observations of filamentary structures of gas at 10(7) kelvin associated with the galaxy cluster Abell 2744. Previous observations of this cluster were unable to resolve and remove coincidental X-ray point sources. After subtracting these, we find hot gas structures that are coherent over scales of 8 megaparsecs. The filaments coincide with over-densities of galaxies and dark matter, with 5-10 per cent of their mass in baryonic gas. This gas has been heated up by the cluster's gravitational pull and is now feeding its core. Our findings strengthen evidence for a picture of the Universe in which a large fraction of the missing baryons reside in the filaments of the cosmic web.

  18. Heavy flavor baryons in hypercentral model

    Indian Academy of Sciences (India)

    Keywords. Hypercentral constituent quark model; charmed and beauty baryons; hyper-Coulomb plus power potential. Abstract. Heavy flavor baryons containing single and double charm (beauty) quarks with light flavor combinations are studied using the hypercentral description of the three-body problem. The confinement ...

  19. Baryon spectroscopy and the omega minus

    Energy Technology Data Exchange (ETDEWEB)

    Samios, N.P.

    1994-12-31

    In this report, I will mainly discuss baryon resonances with emphasis on the discovery of the {Omega}{sup {minus}}. However, for completeness, I will also present some data on the meson resonances which together with the baryons led to the uncovering of the SU(3) symmetry of particles and ultimately to the concept of quarks.

  20. Baryon spectroscopy and the omega minus

    International Nuclear Information System (INIS)

    Samios, N.P.

    1994-01-01

    In this report, I will mainly discuss baryon resonances with emphasis on the discovery of the Ω - . However, for completeness, I will also present some data on the meson resonances which together with the baryons led to the uncovering of the SU(3) symmetry of particles and ultimately to the concept of quarks

  1. The good, the bad, and the baryon

    International Nuclear Information System (INIS)

    Ball, R.D.

    1990-01-01

    We describe the incorporation of baryons into an effective theory of QCD at low energies. The baryon is not a Skyrmion, rather it consists of three valence quarks bound by effective gluon exchanges, enveloped in a meson cloud, which may possibly take the form of a chiral soliton. Some of the physical implications of these results are also discussed. (orig.)

  2. Baryon bags in strong coupling QCD

    Science.gov (United States)

    Gattringer, Christof

    2018-04-01

    We discuss lattice QCD with one flavor of staggered fermions and show that in the path integral the baryon contributions can be fully separated from quark and diquark contributions. The baryonic degrees of freedom (d.o.f.) are independent of the gauge field, and the corresponding free fermion action describes the baryons through the joint propagation of three quarks. The nonbaryonic dynamics is described by quark and diquark terms that couple to the gauge field. When evaluating the quark and diquark contributions in the strong coupling limit, the partition function completely factorizes into baryon bags and a complementary domain. Baryon bags are regions in space-time where the dynamics is described by a single free fermion made out of three quarks propagating coherently as a baryon. Outside the baryon bags, the relevant d.o.f. are monomers and dimers for quarks and diquarks. The partition sum is a sum over all baryon bag configurations, and for each bag, a free fermion determinant appears as a weight factor.

  3. Heavy baryons in the relativistic quark model

    International Nuclear Information System (INIS)

    Ebert, D.; Faustov, R.N.; Galkin, V.O.; Martynenko, A.P.; Saleev, V.A.

    1996-07-01

    In the framework of the relativistic quasipotential quark model the mass spectrum of baryons with two heavy quarks is calculated. The quasipotentials for interactions of two quarks and of a quark with a scalar and axial vector diquark are evaluated. The bound state masses of baryons with J P =1/2 + , 3/2 + are computed. (orig.)

  4. Baryon excitations in the bag model

    International Nuclear Information System (INIS)

    Jaffe, R.L.

    1976-07-01

    Two recent spectroscopic applications of the bag model are discussed. The first is a study of the place of multiquark states in meson and baryon spectroscopy, and the second is an attempt to sort out the P-wave baryon excitations in a bag model. 33 references

  5. Strange baryon production in Z hadronic decays

    CERN Document Server

    Abreu, P; Adye, T; Agasi, E; Ajinenko, I; Aleksan, Roy; Alekseev, G D; Allport, P P; Almehed, S; Alvsvaag, S J; Amaldi, Ugo; Amato, S; Andreazza, A; Andrieux, M L; Antilogus, P; Anykeyev, V B; Apel, W D; Arnoud, Y; Augustin, J E; Augustinus, A; Baillon, Paul; Bambade, P; Barate, R; Bardin, Dimitri Yuri; Barker, G J; Baroncelli, A; Barrio, J A; Bartl, Walter; Bates, M J; Battaglia, Marco; Baubillier, M; Baudot, J; Becks, K H; Begalli, M; Beillière, P; Belokopytov, Yu A; Benvenuti, Alberto C; Berggren, M; Bertrand, D; Bianchi, F; Bigi, M; Bilenky, S M; Billoir, P; Bloch, D; Blume, M; Blyth, S; Bocci, V; Bolognese, T; Bonesini, M; Bonivento, W; Booth, P S L; Borisov, G; Bosio, C; Bosworth, S; Botner, O; Boudinov, E; Bouquet, B; Bourdarios, C; Bowcock, T J V; Bozzo, M; Branchini, P; Brand, K D; Brenner, R A; Bricman, C; Brillault, L; Brown, R C A; Brunet, J M; Brückman, P; Bugge, L; Buran, T; Buys, A; Bärring, O; Caccia, M; Calvi, M; Camacho-Rozas, A J; Camporesi, T; Canale, V; Canepa, M; Cankocak, K; Cao, F; Carena, F; Carrilho, P; Carroll, L; Caso, Carlo; Cassio, V; Castillo-Gimenez, M V; Cattai, A; Cavallo, F R; Cerrito, L; Chabaud, V; Charpentier, P; Chaussard, L; Chauveau, J; Checchia, P; Chelkov, G A; Chikilev, O G; Chliapnikov, P V; Chochula, P; Chorowicz, V; Cindro, V; Collins, P; Contreras, J L; Contri, R; Cortina, E; Cosme, G; Cossutti, F; Crawley, H B; Crennell, D J; Crosetti, G; Cuevas-Maestro, J; Czellar, S; D'Almagne, B; Da Silva, W; Dahl-Jensen, Erik; Dahm, J; Dam, M; Damgaard, G; Daum, A; Dauncey, P D; Davenport, Martyn; De Angelis, A; De Boeck, H; De Brabandere, S; De Clercq, C; De Lotto, B; De Min, A; De Paula, L S; De Saint-Jean, C; Defoix, C; Della Ricca, G; Delpierre, P A; Demaria, N; Di Ciaccio, Lucia; Dijkstra, H; Djama, F; Dolbeau, J; Doroba, K; Dracos, M; Drees, J; Drees, K A; Dris, M; Dufour, Y; Dupont, F; Dönszelmann, M; Edsall, D M; Ehret, R; Eigen, G; Ekelöf, T J C; Ekspong, Gösta; Elsing, M; Engel, J P; Ershaidat, N; Erzen, B; Espirito-Santo, M C; Falk, E; Fassouliotis, D; Feindt, Michael; Ferrer, A; Filippas-Tassos, A; Firestone, A; Fokitis, E; Fontanelli, F; Formenti, F; Franek, B J; Frenkiel, P; Fries, D E C; Frodesen, A G; Frühwirth, R; Fulda-Quenzer, F; Fuster, J A; Föth, H; Fürstenau, H; Gamba, D; Gandelman, M; García, C; García, J; Gaspar, C; Gasparini, U; Gavillet, P; Gazis, E N; Gelé, D; Gerber, J P; Gillespie, D; Gokieli, R; Golob, B; Gopal, Gian P; Gorn, L; Gracco, Valerio; Grard, F; Graziani, E; Grosdidier, G; Gunnarsson, P; Guy, J; Guz, Yu; Górski, M; Günther, M; Haedinger, U; Hahn, F; Hahn, M; Hahn, S; Haider, S; Hajduk, Z; Hallgren, A; Hamacher, K; Hao, W; Harris, F J; Hedberg, V; Henriques, R P; Hernández, J J; Herquet, P; Herr, H; Hessing, T L; Higón, E; Hilke, Hans Jürgen; Hill, T S; Holmgren, S O; Holt, P J; Holthuizen, D J; Houlden, M A; Hrubec, Josef; Huet, K; Hultqvist, K; Ioannou, P; Jackson, J N; Jacobsson, R; Jalocha, P; Janik, R; Jarlskog, G; Jarry, P; Jean-Marie, B; Johansson, E K; Joram, Christian; Juillot, P; Jönsson, L B; Jönsson, P E; Kaiser, M; Kalmus, George Ernest; Kapusta, F; Karlsson, M; Karvelas, E; Katsanevas, S; Katsoufis, E C; Keränen, R; Khomenko, B A; Khovanskii, N N; King, B J; Kjaer, N J; Klein, H; Klovning, A; Kluit, P M; Kokkinias, P; Koratzinos, M; Korcyl, K; Kostyukhin, V; Kourkoumelis, C; Kramer, P H; Krammer, Manfred; Kreuter, C; Kronkvist, I J; Krumshtein, Z; Krupinski, W; Królikowski, J; Kubinec, P; Kucewicz, W; Kurvinen, K L; Kuznetsov, O; Köhne, J H; Köne, B; La Vaissière, C de; Lacasta, C; Laktineh, I; Lamblot, S; Lamsa, J; Lanceri, L; Lane, D W; Langefeld, P; Lapin, V; Last, I; Laugier, J P; Lauhakangas, R; Leder, Gerhard; Ledroit, F; Lefébure, V; Legan, C K; Leitner, R; Lemoigne, Y; Lemonne, J; Lenzen, Georg; Lepeltier, V; Lesiak, T; Liko, D; Lindner, R; Lipniacka, A; Lippi, I; Lokajícek, M; Loken, J G; Loukas, D; Lutz, P; Lyons, L; López, J M; López-Aguera, M A; López-Fernandez, A; Lörstad, B; MacNaughton, J N; Maehlum, G; Maio, A; Malychev, V; Mandl, F; Marco, J; Margoni, M; Marin, J C; Mariotti, C; Markou, A; Maron, T; Martí i García, S; Martínez-Rivero, C; Martínez-Vidal, F; Maréchal, B; Matorras, F; Matteuzzi, C; Matthiae, Giorgio; Mazzucato, M; McCubbin, M L; McKay, R; McNulty, R; Medbo, J; Meroni, C; Meyer, W T; Michelotto, M; Migliore, E; Mirabito, L; Mitaroff, Winfried A; Mjörnmark, U; Moa, T; Monge, M R; Morettini, P; Mundim, L M; Murray, W J; Muryn, B; Myatt, Gerald; Mönig, K; Møller, R; Müller, H; Naraghi, F; Navarria, Francesco Luigi; Navas, S; Negri, P; Neumann, W; Neumeister, N; Nicolaidou, R; Nielsen, B S; Nikolaenko, V; Niss, P; Nomerotski, A; Normand, Ainsley; Némécek, S; Oberschulte-Beckmann, W; Obraztsov, V F; Olshevskii, A G; Onofre, A; Orava, Risto; Ouraou, A; Paganini, P; Paganoni, M; Pagès, P; Palka, H; Papadopoulou, T D; Pape, L; Parodi, F; Passeri, A; Pegoraro, M; Pennanen, J; Peralta, L; Pernegger, H; Perrotta, A; Petridou, C; Petrolini, A; Phillips, H T; Piana, G; Pierre, F; Pimenta, M; Plaszczynski, S; Podobrin, O; Pol, M E; Polok, G; Poropat, P; Pozdnyakov, V; Prest, M; Privitera, P; Pullia, Antonio; Radojicic, D; Ragazzi, S; Rahmani, H; Rames, J; Ratoff, P N; Read, A L; Reale, M; Rebecchi, P; Redaelli, N G; Regler, Meinhard; Reid, D; Renton, P B; Resvanis, L K; Richard, F; Richardson, J; Rinaudo, G; Ripp, I; Romero, A; Roncagliolo, I; Ronchese, P; Roos, L; Rosenberg, E I; Rosso, E; Roudeau, Patrick; Rovelli, T; Ruhlmann-Kleider, V; Ruiz, A; Rídky, J; Rückstuhl, W; Saarikko, H; Sacquin, Yu; Sadovskii, A; Sajot, G; Salt, J; Sannino, M; Schneider, H; Schyns, M A E; Sciolla, G; Scuri, F; Sedykh, Yu; Segar, A M; Seitz, A; Sekulin, R L; Shellard, R C; Siccama, I; Siegrist, P; Simonetti, S; Simonetto, F; Sissakian, A N; Sitár, B; Skaali, T B; Smadja, G; Smirnov, N; Smirnova, O G; Smith, G R; Sosnowski, R; Souza-Santos, D; Spassoff, Tz; Spiriti, E; Squarcia, S; Stanescu, C; Stapnes, Steinar; Stavitski, I; Stepaniak, K; Stichelbaut, F; Stocchi, A; Strauss, J; Strub, R; Stugu, B; Stäck, H; Szczekowski, M; Szeptycka, M; Sánchez, J; Tabarelli de Fatis, T; Tavernet, J P; Tilquin, A; Timmermans, J; Tkatchev, L G; Todorov, T; Toet, D Z; Tomaradze, A G; Tomé, B; Tortora, L; Tranströmer, G; Treille, D; Trischuk, W; Tristram, G; Trombini, A; Troncon, C; Tsirou, A L; Turluer, M L; Tuuva, T; Tyapkin, I A; Tyndel, M; Tzamarias, S; Ullaland, O; Uvarov, V; Valenti, G; Vallazza, E; Van Doninck, W K; Van Eldik, J; Van der Velde, C; Vegni, G; Ventura, L; Venus, W A; Verbeure, F; Verlato, M; Vertogradov, L S; Vilanova, D; Vincent, P; Vitale, L; Vlasov, E; Vodopyanov, A S; Voutilainen, M; Vrba, V; Wahlen, H; Walck, C; Waldner, F; Wehr, A; Weierstall, M; Weilhammer, Peter; Wetherell, Alan M; Wicke, D; Wickens, J H; Wielers, M; Wilkinson, G R; Williams, W S C; Winter, M; Witek, M; Wormser, G; Woschnagg, K; Yip, K; Yu, L; Yushchenko, O P; Zach, F; Zacharatou-Jarlskog, C; Zalewska-Bak, A; Zalewski, Piotr; Zavrtanik, D; Zevgolatakos, E; Zhigunov, V P; Zimin, N I; Zito, M; Zontar, D; Zuberi, R; Zucchelli, G C; Zumerle, G; de Boer, Wim; van Apeldoorn, G W; van Dam, P; Åsman, B; Österberg, K; Überschär, B; Überschär, S

    1995-01-01

    A study of the production of strange octet and decuplet baryons in hadronic decays of the Z recorded by the DELPHI detector at LEP is presented. This includes the first measurement of the \\Sigma^\\pm average multiplicity. The total and differential cross sections, the event topology and the baryon-antibaryon correlations are compared with current hadronization models.

  6. The relative impact of baryons and cluster shape on weak lensing mass estimates of galaxy clusters

    Science.gov (United States)

    Lee, B. E.; Le Brun, A. M. C.; Haq, M. E.; Deering, N. J.; King, L. J.; Applegate, D.; McCarthy, I. G.

    2018-05-01

    Weak gravitational lensing depends on the integrated mass along the line of sight. Baryons contribute to the mass distribution of galaxy clusters and the resulting mass estimates from lensing analysis. We use the cosmo-OWLS suite of hydrodynamic simulations to investigate the impact of baryonic processes on the bias and scatter of weak lensing mass estimates of clusters. These estimates are obtained by fitting NFW profiles to mock data using MCMC techniques. In particular, we examine the difference in estimates between dark matter-only runs and those including various prescriptions for baryonic physics. We find no significant difference in the mass bias when baryonic physics is included, though the overall mass estimates are suppressed when feedback from AGN is included. For lowest-mass systems for which a reliable mass can be obtained (M200 ≈ 2 × 1014M⊙), we find a bias of ≈-10 per cent. The magnitude of the bias tends to decrease for higher mass clusters, consistent with no bias for the most massive clusters which have masses comparable to those found in the CLASH and HFF samples. For the lowest mass clusters, the mass bias is particularly sensitive to the fit radii and the limits placed on the concentration prior, rendering reliable mass estimates difficult. The scatter in mass estimates between the dark matter-only and the various baryonic runs is less than between different projections of individual clusters, highlighting the importance of triaxiality.

  7. Electromagnetic properties of light and heavy baryons in the relativistic quark model

    International Nuclear Information System (INIS)

    Nicmorus Marinescu, Diana

    2007-01-01

    One of the main challenges of nowadays low-energy physics remains the description of the internal structure of hadrons, strongly connected to the electromagnetic properties of matter. In this vein, the success of the relativistic quark model in the analysis of the hadron structure constitutes a solid motivation for the study carried out throughout this work. The relativistic quark model is extended to the investigation of static electromagnetic properties of both heavy and light baryons. The bare contributions to the magnetic moments of the single-, double- and triple-heavy baryons are calculated. Moreover, the relativistic quark model allows the study of the electromagnetic properties of the light baryon octet incorporating meson cloud contributions in a perturbative manner. The long disputed values of the multipole ratios E2/M1 and C2/M1 and the electromagnetic form factors of the N→Δγ transition are successfully reproduced. The relativistic quark model can be viewed as a quantum field theory approach based on a phenomenological Lagrangian coupling light and heavy baryons to their constituent quarks. In our approach the baryon is a composite object of three constituent quarks, at least in leading order. The effective interaction Lagrangian is written in terms of baryon and constituent quark fields. The effective action preserves Lorentz covariance and gauge invariance. The main ingredients of the model are already introduced at the level of the interaction Lagrangian: the three-quark baryon currents, the Gaussian distribution of the constituent quarks inside the baryon and the compositeness condition which sets an upper limit for the baryon-quark vertex. The S-matrix elements are expressed by a set of Feynman quark-diagrams. The model contains only few parameters, namely, the cut-off parameter of the Gaussian quark distribution and the free quark propagator, which are unambiguously determined from the best fit to the data. The heavy quark limit within this

  8. Electromagnetic properties of light and heavy baryons in the relativistic quark model

    Energy Technology Data Exchange (ETDEWEB)

    Nicmorus Marinescu, Diana

    2007-06-14

    One of the main challenges of nowadays low-energy physics remains the description of the internal structure of hadrons, strongly connected to the electromagnetic properties of matter. In this vein, the success of the relativistic quark model in the analysis of the hadron structure constitutes a solid motivation for the study carried out throughout this work. The relativistic quark model is extended to the investigation of static electromagnetic properties of both heavy and light baryons. The bare contributions to the magnetic moments of the single-, double- and triple-heavy baryons are calculated. Moreover, the relativistic quark model allows the study of the electromagnetic properties of the light baryon octet incorporating meson cloud contributions in a perturbative manner. The long disputed values of the multipole ratios E2/M1 and C2/M1 and the electromagnetic form factors of the N{yields}{delta}{gamma} transition are successfully reproduced. The relativistic quark model can be viewed as a quantum field theory approach based on a phenomenological Lagrangian coupling light and heavy baryons to their constituent quarks. In our approach the baryon is a composite object of three constituent quarks, at least in leading order. The effective interaction Lagrangian is written in terms of baryon and constituent quark fields. The effective action preserves Lorentz covariance and gauge invariance. The main ingredients of the model are already introduced at the level of the interaction Lagrangian: the three-quark baryon currents, the Gaussian distribution of the constituent quarks inside the baryon and the compositeness condition which sets an upper limit for the baryon-quark vertex. The S-matrix elements are expressed by a set of Feynman quark-diagrams. The model contains only few parameters, namely, the cut-off parameter of the Gaussian quark distribution and the free quark propagator, which are unambiguously determined from the best fit to the data. The heavy quark limit

  9. Search for Baryons with Two Charm Quarks

    Energy Technology Data Exchange (ETDEWEB)

    Mattson, Mark Edward [Carnegie Mellon U.

    2002-01-01

    Using data from the SELEX experiment, we searched for baryons having two charm quarks. No one has yet observed a doubly-charmed baryon. We investigated the reconstruction $\\Lambda^+_c K⁻ \\pi^+\\pi^+$, a decay mode consistent with a baryon having $ccu$ quarks. We observe an excess of 20 events above an expected background of 31 events, at a mass of 3.76 GeV/$c^2$. We observe differences between the signal events and the background. The mass resolution, mass, and decay mode are consistent with a $ccu$ baryon. The mass and production are higher than theoretical predictions for the ground state $\\Xi^{++}_{cc}$. If the signal is real and not a doubly-charmed baryon, then it is not accounted for by current physics

  10. Abnormal topological organization in white matter structural networks revealed by diffusion tensor tractography in unmedicated patients with obsessive-compulsive disorder.

    Science.gov (United States)

    Zhong, Zhaoxi; Zhao, Tengda; Luo, Jia; Guo, Zhihua; Guo, Meng; Li, Ping; Sun, Jing; He, Yong; Li, Zhanjiang

    2014-06-03

    Obsessive-compulsive disorder (OCD) is a chronic psychiatric disorder defined by recurrent thoughts, intrusive and distressing impulses, or images and ritualistic behaviors. Although focal diverse regional abnormalities white matter integrity in specific brain regions have been widely studied in populations with OCD, alterations in the structural connectivities among them remain poorly understood. The aim was to investigate the abnormalities in the topological efficiency of the white matter networks and the correlation between the network metrics and Yale-Brown Obsessive-Compulsive Scale scores in unmedicated OCD patients, using diffusion tensor tractography and graph theoretical approaches. This study used diffusion tensor imaging and deterministic tractography to map the white matter structural networks in 26 OCD patients and 39 age- and gender-matched healthy controls; and then applied graph theoretical methods to investigate abnormalities in the global and regional properties of the white matter network in these patients. The patients and control participants both showed small-world organization of the white matter networks. However, the OCD patients exhibited significant abnormal global topology, including decreases in global efficiency (t = -2.32, p = 0.02) and increases in shortest path length, Lp (t = 2.30, p = 0.02), the normalized weighted shortest path length, λ (t = 2.08, p=0.04), and the normalized clustering coefficient, γ (t = 2.26, p = 0.03), of their white matter structural networks compared with healthy controls. Further, the OCD patients showed a reduction in nodal efficiency predominately in the frontal regions, the parietal regions and caudate nucleus. The normalized weighted shortest path length of the network metrics was significantly negatively correlated with obsessive subscale of the Yale-Brown Obsessive-Compulsive Scale (r = -0.57, p = 0.0058). These findings demonstrate the abnormal topological efficiency in the white matter networks

  11. The Baryon Number Two System in the Chiral Soliton Model

    International Nuclear Information System (INIS)

    Mantovani-Sarti, V.; Drago, A.; Vento, V.; Park, B.-Y.

    2013-01-01

    We study the interaction between two B = 1 states in a chiral soliton model where baryons are described as non-topological solitons. By using the hedgehog solution for the B = 1 states we construct three possible B = 2 configurations to analyze the role of the relative orientation of the hedgehog quills in the dynamics. The strong dependence of the inter soliton interaction on these relative orientations reveals that studies of dense hadronic matter using this model should take into account their implications. (author)

  12. Baryon Acoustic Oscillations reconstruction with pixels

    Energy Technology Data Exchange (ETDEWEB)

    Obuljen, Andrej [SISSA—International School for Advanced Studies, Via Bonomea 265, 34136 Trieste (Italy); Villaescusa-Navarro, Francisco [Center for Computational Astrophysics, 160 5th Ave, New York, NY, 10010 (United States); Castorina, Emanuele [Berkeley Center for Cosmological Physics, University of California, Berkeley, CA 94720 (United States); Viel, Matteo, E-mail: aobuljen@sissa.it, E-mail: fvillaescusa@simonsfoundation.org, E-mail: ecastorina@berkeley.edu, E-mail: viel@oats.inaf.it [INAF, Osservatorio Astronomico di Trieste, via Tiepolo 11, I-34131 Trieste (Italy)

    2017-09-01

    Gravitational non-linear evolution induces a shift in the position of the baryon acoustic oscillations (BAO) peak together with a damping and broadening of its shape that bias and degrades the accuracy with which the position of the peak can be determined. BAO reconstruction is a technique developed to undo part of the effect of non-linearities. We present and analyse a reconstruction method that consists of displacing pixels instead of galaxies and whose implementation is easier than the standard reconstruction method. We show that this method is equivalent to the standard reconstruction technique in the limit where the number of pixels becomes very large. This method is particularly useful in surveys where individual galaxies are not resolved, as in 21cm intensity mapping observations. We validate this method by reconstructing mock pixelated maps, that we build from the distribution of matter and halos in real- and redshift-space, from a large set of numerical simulations. We find that this method is able to decrease the uncertainty in the BAO peak position by 30-50% over the typical angular resolution scales of 21 cm intensity mapping experiments.

  13. Soft RPV through the baryon portal

    International Nuclear Information System (INIS)

    Krnjaic, Gordan; Tsai, Yuhsin

    2014-01-01

    Supersymmetric (SUSY) models with R-parity generically predict sparticle decays with invisible neutralinos, which yield distinctive missing energy events at colliders. Since most LHC searches are designed with this expectation, the putative bounds on sparticle masses become considerably weaker if R-parity is violated so that squarks and gluinos decay to jets with large QCD backgrounds. Here we introduce a scenario in which baryonic R-parity violation (RPV) arises effectively from soft SUSY breaking interactions, but leptonic RPV remains accidentally forbidden to evade constraints from proton decay and FCNCs. The model features a global R-symmetry that initially forbids RPV interactions, a hidden R-breaking sector, and a heavy mediator that communicates this breaking to the visible sector. After R-symmetry breaking, the mediator is integrated out and an effective RPV A-term arises at tree level; RPV couplings between quarks and squarks arise only at loop level and receive additional suppression. Although this mediator must be heavy compared to soft masses, the model introduces no new hierarchy since viable RPV can arise when the mediator mass is near the SUSY breaking scale. In generic regions of parameter space, a light thermally-produced gravitino is stable and can be a viable dark matter candidate

  14. Search for missing baryons through scintillation

    International Nuclear Information System (INIS)

    Habibi, F.

    2011-06-01

    Cool molecular hydrogen H 2 may be the ultimate possible constituent to the Milky-Way missing baryon. We describe a new way to search for such transparent matter in the Galactic disc and halo, through the diffractive and refractive effects on the light of background stars. By simulating the phase delay induced by a turbulent medium, we computed the corresponding illumination pattern on the earth for an extended source and a given passband. We show that in favorable cases, the light of a background star can be subjected to stochastic fluctuations of the order of a few percent at a characteristic time scale of a few minutes. We have searched for scintillation induced by molecular gas in visible dark nebulae as well as by hypothetical halo clumpuscules of cool molecular hydrogen (H 2 -He) during two nights, using the NTT telescope and the IR SOFI detector. Amongst a few thousands of monitored stars, we found one light-curve that is compatible with a strong scintillation effect through a turbulent structure in the B68 nebula. Because no candidate were found toward the SMC (Small Magellan Cloud), we are able to establish upper limits on the contribution of gas clumpuscules to the Galactic halo mass. We show that the short time-scale monitoring of a few 10 6 star*hour in the visible band with a >4 m telescope and a fast readout camera should allow one to interestingly quantify or constrain the contribution of turbulent molecular gas to the Galactic halo. (author)

  15. TU-CD-BRB-05: Radiation Damage Signature of White Matter Fiber Bundles Using Diffusion Tensor Imaging (DTI)

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, T; Chapman, C; Lawrence, T; Cao, Y [University of Michigan, Ann Arbor, MI (United States); Tsien, C [Washington University at St. Louis, St. Louis, MO (United States)

    2015-06-15

    Purpose: To develop an automated and scalable approach and identify temporal, spatial and dosimetric patterns of radiation damage of white matter (WM) fibers following partial brain irradiation. Methods: An automated and scalable approach was developed to extract DTI features of 22 major WM fibers from 33 patients with low-grade/benign tumors treated by radiation therapy (RT). DTI scans of the patients were performed pre-RT, 3- and 6-week during RT, and 1, 6 and 18 months after RT. The automated tractography analysis was applied to 198 datasets as: (1) intra-subject registration of longitudinal DTI, (2) spatial normalization of individual-patient DTI to the Johns Hopkins WM Atlas, (3) automatic fiber tracking regulated by the WM Atlas, and (4) segmentation of WM into 22 major tract profiles. Longitudinal percentage changes in fractional anisotropy (FA), and mean, axial and radial diffusivity (MD/AD/RD) of each tract from pre-RT were quantified and correlated to 95%, 90% and 80% percentiles of doses and mean doses received by the tract. Heatmaps were used to identify clusters of significant correlation and reveal temporal, spatial and dosimetric signatures of WM damage. A multivariate linear regression was further carried out to determine influence of clinical factors. Results: Of 22 tracts, AD/MD changes in 12 tracts had significant correlation with doses, especially at 6 and 18 months post-RT, indicating progressive radiation damage after RT. Most interestingly, the DTI-index changes in the elongated tracts were associated with received maximum doses, suggesting a serial-structure behavior; while short association fibers were affected by mean doses, indicating a parallel-structure response. Conclusion: Using an automated DTI-tractography analysis of whole brain WM fibers, we reveal complex radiation damage patterns of WM fibers. Damage in WM fibers that play an important role in the neural network could be associated with late neurocognitive function declines

  16. Anisotropies in the diffuse gamma-ray background from dark matter with Fermi LAT: A closer look

    International Nuclear Information System (INIS)

    Cuoco, A.; Sellerholm, A.; Conrad, J.; Hannestad, S.

    2011-01-01

    We perform a detailed study of the sensitivity to the anisotropies related to dark matter (DM) annihilation in the isotropic gamma-ray background (IGRB) as measured by the Fermi Large Area Telescope (Fermi LAT). For the first time, we take into account the effects of the Galactic foregrounds and use a realistic representation of the Fermi LAT. We implement an analysis pipeline which simulates Fermi LAT data sets starting from model maps of the Galactic foregrounds, the Fermi-resolved point sources, the extragalactic diffuse emission and the signal from DM annihilation. The effects of the detector are taken into account by convolving the model maps with the Fermi LAT instrumental response. We then use the angular power spectrum to characterize the anisotropy properties of the simulated data and to study the sensitivity to DM. We consider DM anisotropies of extragalactic origin and of Galactic origin (which can be generated through annihilation in the Milky Way substructures) as opposed to a background of anisotropies generated by sources of astrophysical origin, blazars for example. We find that with statistics from 5 yr of observation, Fermi is sensitive to a DM contribution at the level of 1–10 per cent of the measured IGRB depending on the DM mass m χ and annihilation mode. In terms of the thermally averaged cross-section <σAv>, this corresponds to ~10 –25 cm 3 s –1 , i.e. slightly above the typical expectations for a thermal relic, for low values of the DM mass m χ ≲ 100 GeV. As a result, the anisotropy method for DM searches has a sensitivity comparable to the usual methods based only on the energy spectrum and thus constitutes an independent and complementary piece of information in the DM puzzle.

  17. Disrupted topological properties of brain white matter networks in left temporal lobe epilepsy: a diffusion tensor imaging study.

    Science.gov (United States)

    Xu, Y; Qiu, S; Wang, J; Liu, Z; Zhang, R; Li, S; Cheng, L; Liu, Z; Wang, W; Huang, R

    2014-10-24

    Mesial temporal lobe epilepsy (mTLE) is the most common drug-refractory focal epilepsy in adults. Although previous functional and morphological studies have revealed abnormalities in the brain networks of mTLE, the topological organization of the brain white matter (WM) networks in mTLE patients is still ambiguous. In this study, we constructed brain WM networks for 14 left mTLE patients and 22 age- and gender-matched normal controls using diffusion tensor tractography and estimated the alterations of network properties in the mTLE brain networks using graph theoretical analysis. We found that networks for both the mTLE patients and the controls exhibited prominent small-world properties, suggesting a balanced topology of integration and segregation. However, the brain WM networks of mTLE patients showed a significant increased characteristic path length but significant decreased global efficiency, which indicate a disruption in the organization of the brain WM networks in mTLE patients. Moreover, we found significant between-group differences in the nodal properties in several brain regions, such as the left superior temporal gyrus, left hippocampus, the right occipital and right temporal cortices. The robustness analysis showed that the results were likely to be consistent for the networks constructed with different definitions of node and edge weight. Taken together, our findings may suggest an adverse effect of epileptic seizures on the organization of large-scale brain WM networks in mTLE patients. Copyright © 2014 IBRO. Published by Elsevier Ltd. All rights reserved.

  18. Evaluation of white matter integrity in systemic lupus erythematosus by diffusion tensor magnetic resonance imaging: a study using tract-based spatial statistics

    International Nuclear Information System (INIS)

    Goulart Correa, Diogo; Ventura, Nina; Gasparetto, Emerson Leandro; Zimmermann, Nicolle; Paz Fonseca, Rochele; Batista Pereira, Denis; Netto, Tania Maria; Doring, Thomas M.

    2016-01-01

    The aim of this study was to evaluate the white matter integrity in brains of patients with systemic lupus erythematosus (SLE) using a voxel-based analyses of diffusion tensor imaging (DTI) data. Fifty-seven patients with SLE were compared to 36 control patients who were matched by gender, age, education, and Mini Mental State Examination score. DTI was performed along 30 noncollinear directions in a 1.5 Tesla scanner. For tract-based spatial statistics (TBSS), a white matter skeleton was created, and a permutation-based inference with 5000 permutations and a threshold of p < 0.05 was used to identify abnormalities in fractional anisotropy (FA). The mean (MD), radial (RD), and axial diffusivities (AD) were also projected onto the mean FA skeleton. We found a significant decrease of global FA in SLE patients compared to controls. The areas of reduced FA included the right superior corona radiata, the right superior longitudinal fasciculus, the body of the corpus callosum, the right inferior fronto-occipital fasciculus, the right thalamic radiation, and the right uncinate fasciculus. Patients with SLE also had increased AD and RD in several areas. Substantial overlap of areas with increased AD and RD occurred and were spatially much more extensive than the areas of reduced FA. Significant increases of AD values were concordant to those of RD and MD and more extensive than FA changes. Analyzing all diffusivity parameters, using TBSS, can detect more white matter microstructural changes in patients with SLE than analyzing FA alone. (orig.)

  19. Evaluation of white matter integrity in systemic lupus erythematosus by diffusion tensor magnetic resonance imaging: a study using tract-based spatial statistics

    Energy Technology Data Exchange (ETDEWEB)

    Goulart Correa, Diogo; Ventura, Nina; Gasparetto, Emerson Leandro [Federal University of Rio de Janeiro, Department of Radiology, Hospital Universitario Clementino Fraga Filho, Rio de Janeiro, RJ (Brazil); Clinica de Diagnostico por Imagem (CDPI), Rio de Janeiro, RJ (Brazil); Zimmermann, Nicolle; Paz Fonseca, Rochele [Federal University of Rio de Janeiro, Department of Radiology, Hospital Universitario Clementino Fraga Filho, Rio de Janeiro, RJ (Brazil); Pontifical Catholic University of Rio Grande do Sul, Department of Psychology, Porto Alegre, RS (Brazil); Batista Pereira, Denis; Netto, Tania Maria [Federal University of Rio de Janeiro, Department of Radiology, Hospital Universitario Clementino Fraga Filho, Rio de Janeiro, RJ (Brazil); Doring, Thomas M. [Clinica de Diagnostico por Imagem (CDPI), Rio de Janeiro, RJ (Brazil)

    2016-08-15

    The aim of this study was to evaluate the white matter integrity in brains of patients with systemic lupus erythematosus (SLE) using a voxel-based analyses of diffusion tensor imaging (DTI) data. Fifty-seven patients with SLE were compared to 36 control patients who were matched by gender, age, education, and Mini Mental State Examination score. DTI was performed along 30 noncollinear directions in a 1.5 Tesla scanner. For tract-based spatial statistics (TBSS), a white matter skeleton was created, and a permutation-based inference with 5000 permutations and a threshold of p < 0.05 was used to identify abnormalities in fractional anisotropy (FA). The mean (MD), radial (RD), and axial diffusivities (AD) were also projected onto the mean FA skeleton. We found a significant decrease of global FA in SLE patients compared to controls. The areas of reduced FA included the right superior corona radiata, the right superior longitudinal fasciculus, the body of the corpus callosum, the right inferior fronto-occipital fasciculus, the right thalamic radiation, and the right uncinate fasciculus. Patients with SLE also had increased AD and RD in several areas. Substantial overlap of areas with increased AD and RD occurred and were spatially much more extensive than the areas of reduced FA. Significant increases of AD values were concordant to those of RD and MD and more extensive than FA changes. Analyzing all diffusivity parameters, using TBSS, can detect more white matter microstructural changes in patients with SLE than analyzing FA alone. (orig.)

  20. Weakly interacting dark matter and baryogenesis

    International Nuclear Information System (INIS)

    Gu Peihong; Lindner, Manfred; Sarkar, Utpal; Zhang Xinmin

    2011-01-01

    In the present Universe visible and dark matter contribute comparable energy density although they have different properties. This phenomenon can be explained if the dark matter relic density, originating from a dark matter asymmetry, is fully determined by the baryon asymmetry. Thus the dark matter mass is not arbitrary; rather, it becomes predictive. We realize this scenario in baryon (lepton) number conserving models where two or more neutral singlet scalars decay into two or three baryonic (leptonic) dark matter scalars, and also decay into quarks (leptons) through other on-shell and/or off-shell exotic scalar bilinears. The produced baryon (lepton) asymmetries in the dark matter scalar and in the standard model quarks (leptons) are thus equal and opposite. The dark matter mass can be predicted in a range from a few GeV to a few TeV, depending on the baryon (lepton) numbers of the decaying scalars and the dark matter scalar. The dark matter scalar can interact with the visible matter through the exchange of the standard model Higgs boson, opening a window for the dark matter direct detection experiments. These models also provide testable predictions in the searches for the exotic scalar bilinears at LHC.