The effect of dipolar interaction on the magnetic isotope effect
DEFF Research Database (Denmark)
Mojaza, Matin; Pedersen, Jørgen Boiden; Lukzen, Nikita
2010-01-01
A multi-channel kinetic description is used to study the magnetic isotope effect (MIE) in zero magnetic field. The maximal isotope effect is equal to the number of channels, two for the hyperfine interaction but four for the electron spin dipole–dipole interaction of the intermediate radical pair....... Quantum mechanical calculations agree with these conclusion and show that large MIE may be obtained even in the presence of a strong exchange interaction. The observed magnesium isotope effect on the rate of enzymatic synthesis of adenosine triphosphate (ATP) is approximately 3 implying that the dipolar...... interaction is responsible for the effect. Our calculations provide support for the proposed mechanism....
AC susceptibility as a tool to probe the dipolar interaction in magnetic nanoparticles
Energy Technology Data Exchange (ETDEWEB)
Landi, Gabriel T., E-mail: gtlandi@gmail.com [Universidade Federal do ABC, 09210-580 Santo André (Brazil); Arantes, Fabiana R. [Universidade Federal do ABC, 09210-580 Santo André (Brazil); Cornejo, Daniel R. [Instituto de Física da Universidade de São Paulo, São Paulo 05508-090 (Brazil); Bakuzis, Andris F. [Instituto de Física, Universidade Federal de Goiás, 74690-900 Goiânia-GO (Brazil); Andreu, Irene; Natividad, Eva [Instituto de Ciencia de Materiales de Aragón (ICMA), CSIC-Universidad de Zaragoza, Zaragoza 50018 (Spain)
2017-01-01
The dipolar interaction is known to substantially affect the properties of magnetic nanoparticles. This is particularly important when the particles are kept in a fluid suspension or packed within nano-carriers. In addition to its usual long-range nature, in these cases the dipolar interaction may also induce the formation of clusters of particles, thereby strongly modifying their magnetic anisotropies. In this paper we show how AC susceptibility may be used to obtain information regarding the influence of the dipolar interaction in a sample. We develop a model which includes both aspects of the dipolar interaction and may be fitted directly to the susceptibility data. The usual long-range nature of the interaction is implemented using a mean-field approximation, whereas the particle-particle aggregation is modeled using a distribution of anisotropy constants. The model is then applied to two samples studied at different concentrations. One consists of spherical magnetite nanoparticles dispersed in oil and the other of cubic magnetite nanoparticles embedded on polymeric nanospheres. We also introduce a simple technique to address the presence of the dipolar interaction in a given sample, based on the height of the AC susceptibility peaks for different driving frequencies. - Highlights: We discuss the importance of the dipolar interaction in magnetic nanoparticle samples. It is shown that AC susceptibility may be used to estimate the extent of this interaction. We develop a model that accounts for particle aggregation. The theoretical model is then fitted to distinct magnetite samples.
Dipolar Interaction in a One-Dimensional Ising Ring
Directory of Open Access Journals (Sweden)
Gina Rose Tongco
2004-12-01
Full Text Available As synthesis of low-dimensional magnetic systems become possible, the need for theoretical understanding of their behavior arises. In this work, the authors explore a one-dimensional magnetic structure with the spins having dipolar interaction.
Quantum states with topological properties via dipolar interactions
Energy Technology Data Exchange (ETDEWEB)
Peter, David
2015-06-25
This thesis proposes conceptually new ways to realize materials with topological properties by using dipole-dipole interactions. First, we study a system of ultracold dipolar fermions, where the relaxation mechanism of dipolar spins can be used to reach the quantum Hall regime. Second, in a system of polar molecules in an optical lattice, dipole-dipole interactions induce spin-orbit coupling terms for the rotational excitations. In combination with time-reversal symmetry breaking this leads to topological bands with Chern numbers greater than one.
Phase transitions in random uniaxial systems with dipolar interactions
International Nuclear Information System (INIS)
Schuster, H.G.
1977-01-01
The critical behaviour of random uniaxial ferromagnetic (ferroelectric) systems with both short range and long range dipolar interactions is investigated, using the field theoretic renormalization method of Brezin et al. for the free energy above and below transition point Tsub(c). The randomness is due to externally introduced fluctuations in the short range interactions (quenched case) or (and) magneto-elastic coupling to the lattice (annealed case). Strong deviations in the critical behaviour with respect to the pure systems are found. In the quenched case, e.g., the specific heat C and the coefficient f 2 (of M 3 in the equation of state, where M is the magnetization) change from C proportional to abs ln abs t abs abssup(1/3), f 2 proportional to abs ln abs t abs abs sup(1/3), f 2 proportional to abs ln abs t abs abs -1 in the pure system to C = A+- + C+-exp[-4√ 3 106 abs ln abs t abs abs], f 2 proportional to abs ln abs t abs abs sup(-1/2) (where t = (T-Tsub(c)) / Tsub(c) is the reduced temperature and A+-, C+- are constants) in the random situation. (orig.) [de
Testing strong interaction theories
International Nuclear Information System (INIS)
Ellis, J.
1979-01-01
The author discusses possible tests of the current theories of the strong interaction, in particular, quantum chromodynamics. High energy e + e - interactions should provide an excellent means of studying the strong force. (W.D.L.)
Thermal entanglement and teleportation in a dipolar interacting system
Energy Technology Data Exchange (ETDEWEB)
Castro, C.S., E-mail: ccastro@if.uff.br [Instituto de Física, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza s/n, Gragoatá, 24210-346 Niterói, RJ (Brazil); Centro de Formação de Professores, Universidade Federal do Recôncavo da Bahia, Av. Nestor de Mello Pita, n. 535, 45.300-000 Amargosa, BA (Brazil); Duarte, O.S.; Pires, D.P.; Soares-Pinto, D.O. [Instituto de Física de São Carlos, Universidade de São Paulo, P.O. Box 369, São Carlos, 13560-970 SP (Brazil); Reis, M.S. [Instituto de Física, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza s/n, Gragoatá, 24210-346 Niterói, RJ (Brazil)
2016-04-22
Quantum teleportation, which depends on entangled states, is a fascinating subject and an important branch of quantum information processing. The present work reports the use of a dipolar spin thermal system as a noisy quantum channel to perform quantum teleportation. Non-locality, tested by violation of Bell's inequality and thermal entanglement, measured by negativity, shows that for the present model all entangled states, even those that do not violate Bell's inequality, are useful for teleportation. - Highlights: • The effects of a dipolar interaction between two spins on their degree of entanglement and non-locality is reported. • The model presents some degree of non-locality and entanglement at a given coupling parameters. • It is shown how the magnetic anisotropies can influence the fidelity of teleportation.
Dipolar interaction in arrays of magnetic nanotubes
International Nuclear Information System (INIS)
Velázquez-Galván, Y; Martínez-Huerta, J M; Encinas, A; De La Torre Medina, J; Danlée, Y; Piraux, L
2014-01-01
The dipolar interaction field in arrays of nickel nanotubes has been investigated on the basis of expressions derived from the effective demagnetizing field of the assembly as well as magnetometry measurements. The model incorporates explicitly the wall thickness and aspect ratio, as well as the spatial order of the nanotubes. The model and experiment show that the interaction field in nanotubes is smaller than that in solid nanowires due to the packing fraction reduction in tubes related to their inner cavity. Finally, good agreement between the model and experiment is found for the variation of the interaction field as a function of the tube wall thickness. (paper)
Dipolar and Non-Dipolar Interactions in LiTbF4
DEFF Research Database (Denmark)
Holmes, L. M.; Als-Nielsen, Jens Aage; Guggenheim, H. J.
1975-01-01
The magnetic interactions in LiTbF4 have been studied in measurements of the quasielastic scattering of neutrons from the paramagnetic crystal. Scattering data have been collected at a temperature T=18.6 K, which is 6.5 times the Curie temperature of LiTbF4, and have been least-squares fitted...... with an expression for the scattering cross section which includes, in addition to the dominant dipolar coupling, two exchange parameters J1 and J2 describing the nondipolar coupling between nearest- and next-nearest-neighbor Tb3+ ions, respectively. The derived exchange parameters are J1/k=-0.26±0.09 K and J2/k=+0...
International Nuclear Information System (INIS)
Ebata, T.
1981-01-01
With an assumed weak multiplet structure for bosonic hadrons, which is consistent with the ΔI = 1/2 rule, it is shown that the strong interaction effective hamiltonian is compatible with the weak SU(2) x U(1) gauge transformation. Especially the rho-meson transforms as a triplet under SU(2)sub(w), and this is the origin of the rho-photon analogy. It is also shown that the existence of the non-vanishing Cabibbo angle is a necessary condition for the absence of the exotic hadrons. (orig.)
Strong-interaction nonuniversality
International Nuclear Information System (INIS)
Volkas, R.R.; Foot, R.; He, X.; Joshi, G.C.
1989-01-01
The universal QCD color theory is extended to an SU(3) 1 direct product SU(3) 2 direct product SU(3) 3 gauge theory, where quarks of the ith generation transform as triplets under SU(3)/sub i/ and singlets under the other two factors. The usual color group is then identified with the diagonal subgroup, which remains exact after symmetry breaking. The gauge bosons associated with the 16 broken generators then form two massive octets under ordinary color. The interactions between quarks and these heavy gluonlike particles are explicitly nonuniversal and thus an exploration of their physical implications allows us to shed light on the fundamental issue of strong-interaction universality. Nonuniversality and weak flavor mixing are shown to generate heavy-gluon-induced flavor-changing neutral currents. The phenomenology of these processes is studied, as they provide the major experimental constraint on the extended theory. Three symmetry-breaking scenarios are presented. The first has color breaking occurring at the weak scale, while the second and third divorce the two scales. The third model has the interesting feature of radiatively induced off-diagonal Kobayashi-Maskawa matrix elements
Dipolar Interaction and Magneto-Viscoelasticity in Nanomagnetic Fluid.
Basheed, G A; Jain, Komal; Pathak, Saurabh; Pant, R P
2018-04-01
We investigate the effect of dilution on dipolar interaction with linear and non-linear rheological properties of kerosene based magnetic fluid. The steady-state behavior demonstrate a shear thinning behavior and corroborated with a power law, (η = c γ ˙ n + η∞) exponent, n ≤ 1. The shear-induced-breakup (separation) of nanoparticles and the yielding behavior has been explained by Bingham model. Moreover, the magnetoviscous effect showed an initial increase at low shear rate and decrease at higher shear rate. Further, specific viscosity (ηF)-versus-Mason number (Mn) shows a perfect scaling at lower Mn (≤10-4) confirming negligible thermal and colloidal forces. Whereas, at higher Mn (≥10-3) deviation from collapse indicates the dominance of Brownian forces acting on nanofluids. The magnetic field dependent elastic (G') and viscous (G″) modulus reveal a crossover from viscoelastic-to-viscous behavior of nanofluid at critical concentration. Finally, we compare viscoelastic results with De Gans diagonal scaling theory to correlate the functional dependence of storage and loss modules with different particle volume concentration.
The phase transition in the anisotropic Heisenberg model with long range dipolar interactions
International Nuclear Information System (INIS)
Mól, L.A.S.; Costa, B.V.
2014-01-01
In this work we have used extensive Monte Carlo calculations to study the planar to paramagnetic phase transition in the two-dimensional anisotropic Heisenberg model with dipolar interactions (AHd) considering the true long-range character of the dipolar interactions by means of the Ewald summation. Our results are consistent with an order–disorder phase transition with unusual critical exponents in agreement with our previous results for the Planar Rotator model with dipolar interactions. Nevertheless, our results disagree with the Renormalization Group results of Maier and Schwabl [Phys. Rev. B, 70, 134430 (2004)] [13] and the results of Rapini et al. [Phys. Rev. B, 75, 014425 (2007)] [12], where the AHd was studied using a cut-off in the evaluation of the dipolar interactions. We argue that besides the long-range character of dipolar interactions their anisotropic character may have a deeper effect in the system than previously believed. Besides, our results show that the use of a cut-off radius in the evaluation of dipolar interactions must be avoided when analyzing the critical behavior of magnetic systems, since it may lead to erroneous results. - Highlights: • The anisotropic Heisenberg model with dipolar interactions is studied. • True long-range interactions were considered by means of Ewald summation. • We found an order–disorder phase transition with unusual critical exponents. • Previous results show a different behavior when a cut-off radius is introduced. • The use of a cut-off radius must be avoided when dealing with dipolar systems
Competition between dipolar and exchange interparticle interactions in magnetic nanoparticle films
Kechrakos, D
2003-01-01
The concentration dependence of the remanence, the coercivity and the blocking temperature of a three-dimensional random assembly of ferromagnetic nanoparticles interacting via exchange and dipolar forces is studied by Monte Carlo simulations. We find that interactions always suppress the coercivity, while they have opposite effects on the remanence of the sample. The crossover from dipolar-coupled to exchange-coupled behavior occurs when the two types of interactions have comparable strengths. The blocking temperature is always enhanced due to interactions, except for the case that particles coalesce and the sample is above the percolation threshold.
Strong interaction phenomenology
International Nuclear Information System (INIS)
Giffon, M.
1989-01-01
A brief review of high energy hadronic data (Part I)is followed by an introduction to the standard (Weinberg Salam Glashow) model of electroweak interactions and its extension to the hadrons (Part II). Rudiments of QCD and of the parton model area given in Part III together with a quick review of the spectroscopy of heavy flavours whereas Part IV is devoted to the introduction to deep inelastic scattering and to the so-called EMC effects. (author)
Pan, H. L.; Li, X.; Zhang, Q.; Su, Y. P.; Wang, J. T.; Xie, W. H.; Zhao, Z. J.
2018-04-01
The magnetic dipolar interactions among multiple FINEMET ribbons have been studied by longitudinally driven magneto-impedance effect (LDMI) and hysteresis loops in this paper. The effect of dipolar fields on LDMI apparently expands the "bell" magneto-impedance profiles and raises its characteristic frequency. This is essentially correlated with the domain nucleation process under the combined effect of ac driving field and dc external field. A theoretical model was utilized to explicate the LDMI variation with the number of ribbons N. Basically, the nucleation field varied linearly with N. The influence of the frequency of ac current causes the increase of the nucleation field by adding a term He ∼f0.38 before 4 MHz, but the dipolar field barely decreases with ac current. At frequency of 10 kHz, the dipolar field is fitted to be about 0.69 Oe, and the geometric factor can be estimated to be 5.60 × 10-5. Additionally the nucleation field reduces slightly due to the compensation of the alternating field, while the LDMI ratio changes obviously. The results indicate that LDMI can be employed as a sensitive tool to reveal the dipolar interaction in FINEMET ribbons and facilitate the design of the materials for magnetic devices.
The structure of the interface in the solvent mediated interaction of dipolar surfaces
International Nuclear Information System (INIS)
Dzhavakhidze, P.G.; Levadny, V.G.
1987-08-01
Interaction of two dipolar surfaces separated by a polar medium is considered within the framework of nonlocal electrostatics. The dipolar surface layers are modelled as regular lattices with fixed orientation of dipoles which are immersed into the solvent; solvent response is characterized by nonlocal dielectric function. The model is elaborated in order to reveal the role of the dipolar layer discreteness in the electric field produced by one surface and the interaction between two surfaces (which gives rise to the so called ''hydration'' or ''structural'' force acting between mineral surfaces and phospholipid bilayers). The discreteness effects are present only for commensurate lattices. Their special mutual arrangement then may lead to considerable reduction of structural forces, viz. the usual repulsion regime may change at short distances to attraction. Conditions are considered when repulsion is entirely replaced by attraction, i.e. the ''hydration barrier'' disappears. In appended note we discuss the role of solvation of surface dipolar groups. We propose an explanation of why two modes of decay (one with oscillative fine structure) may be present in the dependence of the force upon distance if the surface dipolar groups are immersed deep enough in the solvent and how the long-range oscillative mode disappears when the surface is but weakly solvated. (author). 35 refs, 5 figs
Wu, Shan; Burlingame, Quinn; Cheng, Zhao-Xi; Lin, Minren; Zhang, Q. M.
2014-12-01
Dielectric materials with high electric energy density and low loss are of great importance for applications in modern electronics and electrical systems. Strongly dipolar materials have the potential to reach relatively higher dielectric constants than the widely used non-polar or weakly dipolar polymers, as well as a much lower loss than that of nonlinear high K polymer dielectrics or polymer-ceramic composites. To realize the high energy density while maintaining the low dielectric loss, aromatic polythioureas and polyureas with high dipole moments, high dipole densities, tunable molecular structures and dielectric properties were investigated. High energy density (>24 J/cm3), high breakdown strength (>800 MV/m), and high charge-discharge efficiency (>90%) can be achieved in the new polymers. The molecular structure and film surface morphology were also studied; it is of great importance to optimize the fabrication process to make high-quality thin films.
Energy Technology Data Exchange (ETDEWEB)
Pelaez, Jose R
1998-12-14
We present a brief pedagogical introduction to the Effective Electroweak Chiral Lagrangians, which provide a model independent description of the WW interactions in the strong regime. When it is complemented with some unitarization or a dispersive approach, this formalism allows the study of the general strong scenario expected at the LHC, including resonances.
Strong interaction at finite temperature
Indian Academy of Sciences (India)
Abstract. We review two methods discussed in the literature to determine the effective parameters of strongly interacting particles as they move through a heat bath. The first one is the general method of chiral perturbation theory, which may be readily applied to this problem. The other is the method of thermal QCD sum rules ...
Quantum-well exciton dipolar interaction: Polarization-dependence and Z-LT splitting
International Nuclear Information System (INIS)
Nguyen Ba An.
1996-12-01
We calculate the exciton dipolar interaction in a semiconductor quantum well. The explicit polarization-dependence, i.e, the dependence on both the exciton dipole moment μ-vector and its inplane wavevector k-vector is derived. The obtained results for the three modes (L, T and Z modes) of the long-range part of the dipolar interaction satisfy the polarization sum rule for any parameters. In the long wavelength limit there is a Z-LT splitting which decreases as the well width increases reflecting a crossover from strict 2D to quasi-2D. A rough crossover from quasi-2D to 3D is also described. (author). 18 refs, 4 figs
Existence of solitary waves in dipolar quantum gases
Antonelli, Paolo
2011-02-01
We study a nonlinear Schrdinger equation arising in the mean field description of dipolar quantum gases. Under the assumption of sufficiently strong dipolar interactions, the existence of standing waves, and hence solitons, is proved together with some of their properties. This gives a rigorous argument for the possible existence of solitary waves in BoseEinstein condensates, which originate solely due to the dipolar interaction between the particles. © 2010 Elsevier B.V. All rights reserved.
Rivas Rojas, P. C.; Tancredi, P.; Moscoso Londoño, O.; Knobel, M.; Socolovsky, L. M.
2018-04-01
Single and fixed size core, core-shell nanoparticles of iron oxides coated with a silica layer of tunable thickness were prepared by chemical routes, aiming to generate a frame of study of magnetic nanoparticles with controlled dipolar interactions. The batch of iron oxides nanoparticles of 4.5 nm radii, were employed as cores for all the coated samples. The latter was obtained via thermal decomposition of organic precursors, resulting on nanoparticles covered with an organic layer that was subsequently used to promote the ligand exchange in the inverse microemulsion process, employed to coat each nanoparticle with silica. The amount of precursor and times of reaction was varied to obtain different silica shell thicknesses, ranging from 0.5 nm to 19 nm. The formation of the desired structures was corroborated by TEM and SAXS measurements, the core single-phase spinel structure was confirmed by XRD, and superparamagnetic features with gradual change related to dipolar interaction effects were obtained by the study of the applied field and temperature dependence of the magnetization. To illustrate that dipolar interactions are consistently controlled, the main magnetic properties are presented and analyzed as a function of center to center minimum distance between the magnetic cores.
Strongly Interacting Light Dark Matter
Directory of Open Access Journals (Sweden)
Sebastian Bruggisser, Francesco Riva, Alfredo Urbano
2017-09-01
Full Text Available In the presence of approximate global symmetries that forbid relevant interactions, strongly coupled light Dark Matter (DM can appear weakly coupled at small energy and generate a sizable relic abundance. Fundamental principles like unitarity restrict these symmetries to a small class, where the leading interactions are captured by effective operators up to dimension-8. Chiral symmetry, spontaneously broken global symmetries and non-linearly realized supersymmetry are examples of this. Their DM candidates (composite fermions, pseudo Nambu-Goldstone Bosons and Goldstini are interesting targets for LHC missing-energy searches.
Strongly interacting light dark matter
International Nuclear Information System (INIS)
Bruggisser, Sebastian; Riva, Francesco; Urbano, Alfredo
2016-07-01
In the presence of approximate global symmetries that forbid relevant interactions, strongly coupled light Dark Matter (DM) can appear weakly coupled at small-energy and generate a sizable relic abundance. Fundamental principles like unitarity restrict these symmetries to a small class, where the leading interactions are captured by effective operators up to dimension-8. Chiral symmetry, spontaneously broken global symmetries and non-linearly realized supersymmetry are examples of this. Their DM candidates (composite fermions, pseudo-Nambu-Goldstone Bosons and Goldstini) are interesting targets for LHC missing-energy searches.
Scalar strong interaction hadron theory
Hoh, Fang Chao
2015-01-01
The scalar strong interaction hadron theory, SSI, is a first principles' and nonlocal theory at quantum mechanical level that provides an alternative to low energy QCD and Higgs related part of the standard model. The quark-quark interaction is scalar rather than color-vectorial. A set of equations of motion for mesons and another set for baryons have been constructed. This book provides an account of the present state of a theory supposedly still at its early stage of development. This work will facilitate researchers interested in entering into this field and serve as a basis for possible future development of this theory.
Anand, Manish; Carrey, Julian; Banerjee, Varsha
2018-05-01
We undertake comprehensive simulations of 2d arrays (Lx ×Ly) of magnetic nanoparticles (MNPs) with dipole-dipole interactions by solving LLG equations. Our primary interest is to understand the correspondence between equilibrium spin (ES) morphologies and tunnel magnetoresistance (TMR) as a function of Θ - the ratio of the dipolar to the anisotropy strength, sample size Lx , aspect ratio Ar =Ly /Lx and the direction of the applied field H → = HêH . The parameter Θ is varied by choosing three distinct particles: (i) α -Fe2O3 (Θ ≃ 0) , (ii) Co (Θ ≃ 0.37) and (iii) Fe3O4 (Θ ≃ 1.28) . Our main observations are as follows: (a) For weakly interacting spins (Θ ≃ 0) , the morphology has randomly oriented magnetic moments for all sample sizes and aspect ratios. The TMR exhibits a peak value of 50% at the coercive field Hc . It is robust with respect to Lx and Ar , and isotropic with respect to êH . (b) For strong interactions (Θ > 1) , the moments order in the plane of the sample. The ES morphology comprises of magnetically aligned regions interspersed with flux closure loops. For fields along x or y, the maximum TMR amplitude decrease to ∼30%. For êH = z ̂ , it drops to ∼3%. The TMR is robust with respect to Lx and Ar and isotropic in the x and y directions only. (c) In strongly interacting samples (Θ > 1) with Lx comparable to the size of a flux closure loop, increasing Ar creates ferromagnetic chains in the sample oriented along y or - y . Consequently, for êH = y ̂ , the TMR magnitude for Ar = 1 is ∼33% while that for Ar = 32 drops to ∼16%. For êH = x ̂ on the other hand, it is ∼30% and independent of Ar . The TMR of long ribbons of MNPs has a strong dependence on Ar and is anisotropic in all three directions.
Energy Technology Data Exchange (ETDEWEB)
Moscoso-Londoño, O., E-mail: omoscoso@ifi.unicamp.br [Instituto de Física ‘Gleb Wataghin’, Universidade Estadual de Campinas (UNICAMP), CEP13083-859 Campinas, São Paulo (Brazil); Tancredi, P. [Laboratorio de Sólidos Amorfos, INTECIN, Facultad de Ingeniería, Universidad de Buenos Aires (UBA), CONICET, C1063ACV Buenos Aires (Argentina); Muraca, D. [Instituto de Física ‘Gleb Wataghin’, Universidade Estadual de Campinas (UNICAMP), CEP13083-859 Campinas, São Paulo (Brazil); Centro de Ciencias Naturais e Humanas, Universidade Federal do ABC (UFABC), Av. Dos Estados, 5001, Santo André, SP (Brazil); Mendoza Zélis, P.; Coral, D.; Fernández van Raap, M.B. [Instituto de Física, Universidad Nacional de La Plata (UNLP), CONICET, CC.67, 1900 La Plata, Buenos Aires (Argentina); Wolff, U.; Neu, V.; Damm, C. [IFW Dresden, Leibniz Institute for Solid State and Materials Research, Dresden, Helmholtzstrasse 20, 01069 Dresden (Germany); Oliveira, C.L.P. de [Instituto de Física, Universidade de São Paulo, São Paulo 05314970 (Brazil); Pirota, K.R. [Instituto de Física ‘Gleb Wataghin’, Universidade Estadual de Campinas (UNICAMP), CEP13083-859 Campinas, São Paulo (Brazil); and others
2017-04-15
Controlled magnetic granular materials with different concentrations of magnetite nanoparticles immersed in a non-conducting polymer matrix were synthesized and, their macroscopic magnetic observables analyzed in order to advance towards a better understanding of the magnetic dipolar interactions and its effects on the obtained magnetic parameters. First, by means of X-ray diffraction, transmission electron microscopy, small angle X-ray scattering and X-ray absorption fine structure an accurate study of the structural properties was carried out. Then, the magnetic properties were analyzed by means of different models, including those that consider the magnetic interactions through long-range dipolar forces as: the Interacting Superparamagnetic Model (ISP) and the Vogel-Fulcher law (V-F). In systems with larger nanoparticle concentrations, magnetic results clearly indicate that the role played by the dipolar interactions affects the magnetic properties, giving rise to obtaining magnetic and structural parameters without physical meaning. Magnetic parameters as the effective anisotropic constant, magnetic moment relaxation time and mean blocking temperature, extracted from the application of the ISP model and V-F Law, were used to simulate the zero-field-cooling (ZFC) and field-cooling curves (FC). A comparative analysis of the simulated, fitted and experimental ZFC/FC curves suggests that the current models depict indeed our dilute granular systems. Notwithstanding, for concentrated samples, the ISP model infers that clustered nanoparticles are being interpreted as single entities of larger magnetic moment and volume, effect that is apparently related to a collective and complex magnetic moment dynamics within the cluster. - Highlights: • Nanoparticle architecture into matrices determines the composite magnetic response. • Magnetically diluted or compacted systems are useful to study magnetism at nanoscale. • Particle aggregation into the matrices was examined
Moscoso-Londoño, O.; Tancredi, P.; Muraca, D.; Mendoza Zélis, P.; Coral, D.; Fernández van Raap, M. B.; Wolff, U.; Neu, V.; Damm, C.; de Oliveira, C. L. P.; Pirota, K. R.; Knobel, M.; Socolovsky, L. M.
2017-04-01
Controlled magnetic granular materials with different concentrations of magnetite nanoparticles immersed in a non-conducting polymer matrix were synthesized and, their macroscopic magnetic observables analyzed in order to advance towards a better understanding of the magnetic dipolar interactions and its effects on the obtained magnetic parameters. First, by means of X-ray diffraction, transmission electron microscopy, small angle X-ray scattering and X-ray absorption fine structure an accurate study of the structural properties was carried out. Then, the magnetic properties were analyzed by means of different models, including those that consider the magnetic interactions through long-range dipolar forces as: the Interacting Superparamagnetic Model (ISP) and the Vogel-Fulcher law (V-F). In systems with larger nanoparticle concentrations, magnetic results clearly indicate that the role played by the dipolar interactions affects the magnetic properties, giving rise to obtaining magnetic and structural parameters without physical meaning. Magnetic parameters as the effective anisotropic constant, magnetic moment relaxation time and mean blocking temperature, extracted from the application of the ISP model and V-F Law, were used to simulate the zero-field-cooling (ZFC) and field-cooling curves (FC). A comparative analysis of the simulated, fitted and experimental ZFC/FC curves suggests that the current models depict indeed our dilute granular systems. Notwithstanding, for concentrated samples, the ISP model infers that clustered nanoparticles are being interpreted as single entities of larger magnetic moment and volume, effect that is apparently related to a collective and complex magnetic moment dynamics within the cluster.
Farhan, Alan; Petersen, Charlotte F; Dhuey, Scott; Anghinolfi, Luca; Qin, Qi Hang; Saccone, Michael; Velten, Sven; Wuth, Clemens; Gliga, Sebastian; Mellado, Paula; Alava, Mikko J; Scholl, Andreas; van Dijken, Sebastiaan
2017-10-17
Geometrical frustration occurs when entities in a system, subject to given lattice constraints, are hindered to simultaneously minimize their local interactions. In magnetism, systems incorporating geometrical frustration are fascinating, as their behavior is not only hard to predict, but also leads to the emergence of exotic states of matter. Here, we provide a first look into an artificial frustrated system, the dipolar trident lattice, where the balance of competing interactions between nearest-neighbor magnetic moments can be directly controlled, thus allowing versatile tuning of geometrical frustration and manipulation of ground state configurations. Our findings not only provide the basis for future studies on the low-temperature physics of the dipolar trident lattice, but also demonstrate how this frustration-by-design concept can deliver magnetically frustrated metamaterials.Artificial magnetic nanostructures enable the study of competing frustrated interactions with more control over the system parameters than is possible in magnetic materials. Farhan et al. present a two-dimensional lattice geometry where the frustration can be controlled by tuning the unit cell parameters.
Control of dipolar relaxation in external fields
Pasquiou, B.; Bismut, G.; Beaufils, Q.; Crubellier, A.; Maréchal, E.; Pedri, P.; Vernac, L.; Gorceix, O.; Laburthe-Tolra, B.
2010-04-01
We study dipolar relaxation in both ultracold thermal and Bose-condensed Cr atom gases. We show three different ways to control dipolar relaxation, making use of either a static magnetic field, an oscillatory magnetic field, or an optical lattice to reduce the dimensionality of the gas from three-dimensional (3D) to two-dimensional (2D). Although dipolar relaxation generally increases as a function of a static magnetic-field intensity, we find a range of nonzero magnetic-field intensities where dipolar relaxation is strongly reduced. We use this resonant reduction to accurately determine the S=6 scattering length of Cr atoms: a6=103±4a0. We compare this new measurement to another new determination of a6, which we perform by analyzing the precise spectroscopy of a Feshbach resonance in d-wave collisions, yielding a6=102.5±0.4a0. These two measurements provide, by far, the most precise determination of a6 to date. We then show that, although dipolar interactions are long-range interactions, dipolar relaxation only involves the incoming partial wave l=0 for large enough magnetic-field intensities, which has interesting consequences on the stability of dipolar Fermi gases. We then study ultracold Cr gases in a one-dimensional (1D) optical lattice resulting in a collection of independent 2D gases. We show that dipolar relaxation is modified when the atoms collide in reduced dimensionality at low magnetic-field intensities, and that the corresponding dipolar relaxation rate parameter is reduced by a factor up to 7 compared to the 3D case. Finally, we study dipolar relaxation in the presence of rf oscillating magnetic fields, and we show that both the output channel energy and the transition amplitude can be controlled by means of the rf frequency and Rabi frequency.
Effect of Dipolar Interactions on the Magnetization of Single-Molecule Magnets in a cubic lattice
Alcantara Ortigoza, Marisol
2005-03-01
Since the one-body tunnel picture of single-molecule magnets (SMM) is not always sufficient to explain the fine structure of experimental hysteresis loops, the effect of intermolecular dipolar interactions has been investigated on an ensemble of 100 3D-systems of 5X5X4 particles, each with spin S = 5, arranged in a cubic lattice. We have solved the Landau-Lifshitz-Gilbert equation for several values of the damping constant, the field sweep rate and the lattice constant. We find that the smaller the damping constant is, the stronger the maximum field needs to be to produce hysteresis. Furthermore, the shape of the hysteresis loops also depends on the damping constant. We also find that the system magnetizes and demagnetizes faster with decreasing sweep rates, resulting in smaller hysteresis loops. Variations of the lattice constant within realistic values (1.5nm and 2.5nm) show that the dipolar interaction plays an important role in magnetic hysteresis by controlling the relaxation process. Examination of temperature dependencies (0.1K and 0.7K) of the above will be presented and compared with recent experimental data on SMM.
Déjardin, J.-L.; Vernay, F.; Respaud, M.; Kachkachi, H.
2017-05-01
We address the issue of inter-particle dipolar interactions in the context of magnetic hyperthermia. More precisely, the main question dealt with here is concerned with the conditions under which the specific absorption rate is enhanced or reduced by dipolar interactions. For this purpose, we propose a theory for the calculation of the AC susceptibility, and thereby the specific absorption rate, for a monodisperse two-dimensional assembly of nanoparticles with oriented anisotropy, in the presence of a DC magnetic field, in addition to the AC magnetic field. We also study the competition between the dipolar interactions and the DC field, both in the transverse and longitudinal configurations. In both cases, we find that the specific absorption rate has a maximum at some critical DC field that depends on the inter-particle separation. In the longitudinal setup, this critical field falls well within the range of experiments.
Strongly interacting photons and atoms
International Nuclear Information System (INIS)
Alge, W.
1999-05-01
This thesis contains the main results of the research topics I have pursued during the my PhD studies at the University of Innsbruck and partly in collaboration with the Institut d' Optique in Orsay, France. It is divided into three parts. The first and largest part discusses the possibility of using strong standing waves as a tool to cool and trap neutral atoms in optical cavities. This is very important in the field of nonlinear optics where several successful experiments with cold atoms in cavities have been performed recently. A discussion of the optical parametric oscillator in a regime where the nonlinearity dominates the evolution is the topic of the second part. We investigated mainly the statistical properties of the cavity output of the three interactive cavity modes. Very recently a system has been proposed which promises fantastic properties. It should exhibit a giant Kerr nonlinearity with negligible absorption thus leading to a photonic turnstile device based on cold atoms in cavity. We have shown that this model suffers from overly simplistic assumptions and developed several more comprehensive approaches to study the behavior of this system. Apart from the division into three parts of different contents the thesis is divided into publications, supplements and invisible stuff. The intention of the supplements is to reach researchers which work in related areas and provide them with more detailed information about the concepts and the numerical tools we used. It is written especially for diploma and PhD students to give them a chance to use the third part of our work which is actually the largest one. They consist of a large number of computer programs we wrote to investigate the behavior of the systems in parameter regions where no hope exists to solve the equations analytically. (author)
Dynamic effects of dipolar interactions on the magnetic behavior of magnetite nanoparticles
Allia, Paolo; Tiberto, Paola
2011-12-01
Isothermal magnetization and initial dc susceptibility of spheroidal, nearly monodisperse magnetite nanoparticles (typical diameter: 8 nm) prepared by a standard thermo-chemical route have been measured between 10 and 300 K. The samples contained magnetite nanoparticles in the form of either a dried powder (each nanoparticle being surrounded by a stable oleic acid shell as a result of the preparation procedure) or a solid dispersion in PEGDA-600 polymer; different nanoparticle (NP) concentrations in the polymer were studied. In all samples the NPs were not tightly agglomerated nor their ferromagnetic cores were directly touching. The high-temperature inverse magnetic susceptibility is always found to follow a linear law as a function of T, crossing the horizontal axis at negative temperatures ranging from 175 to about 1,000 K. The deviation from the standard superparamagnetic behavior is related to dipolar interaction among NPs; however, a careful analysis makes it hard to conclude that such a behavior originates from a dominant antiferromagnetic character of the interaction. The results are well explained considering that the studied samples are in the interacting superparamagnetic (ISP) regime. The ISP model is basically a mean field theory which allows one to straightforwardly account for the role of magnetic dipolar interaction in a NP system. The model predicts the existence of specific scaling laws for the reduced magnetization which have been confirmed in all studied samples. The interaction of each magnetic dipole moment with the local, random dipolar field produced by the other dipoles results in the presence of a large fluctuating energy term whose magnitude is comparable to the static barrier for magnetization reversal/rotation related to magnetic anisotropy. On the basis of the existing theories on thermal crossing of a barrier whose height randomly fluctuates in time it is predicted that the rate of barrier crossing is substantially driven by the rate
Wang, B. X.; Zhao, C. Y.
2018-02-01
Understanding radiative transfer in random media like micro- or nanoporous and particulate materials, allows people to manipulate the scattering and absorption of radiation, as well as opens new possibilities in applications such as imaging through turbid media, photovoltaics, and radiative cooling. A strong-backscattering phase function, i.e., a negative scattering asymmetry parameter g , is of great interest, which can possibly lead to unusual radiative transport phenomena, for instance, Anderson localization of light. Here we demonstrate that by utilizing the structural correlations and second Kerker condition for a disordered medium composed of randomly distributed silicon nanoparticles, a strongly negative scattering asymmetry factor (g ˜-0.5 ) for multiple light scattering can be realized in the near infrared. Based on the multipole expansion of Foldy-Lax equations and quasicrystalline approximation (QCA), we have rigorously derived analytical expressions for the effective propagation constant and scattering phase function for a random system containing spherical particles, by taking the effect of structural correlations into account. We show that as the concentration of scattering particles rises, the backscattering is also enhanced. Moreover, in this circumstance, the transport mean free path is largely reduced and even becomes smaller than that predicted by independent scattering approximation. We further explore the dependent scattering effects, including the modification of electric and magnetic dipole excitations and far-field interference effect, both induced and influenced by the structural correlations, for volume fraction of particles up to fv˜0.25 . Our results have profound implications in harnessing micro- or nanoscale radiative transfer through random media.
Stacking of purines in water: the role of dipolar interactions in caffeine.
Tavagnacco, L; Di Fonzo, S; D'Amico, F; Masciovecchio, C; Brady, J W; Cesàro, A
2016-05-11
During the last few decades it has been ascertained that base stacking is one of the major contributions stabilizing nucleic acid conformations. However, the understanding of the nature of the interactions involved in the stacking process remains under debate and it is a subject of theoretical and experimental studies. Structural similarity between purine bases (guanine and adenine) in DNA and the caffeine molecule makes caffeine an excellent model for the purine bases. The present study clearly shows that dipolar interactions play a fundamental role in determining stacking of purine molecules in solution. In order to reach this achievement, polarized ultraviolet Raman resonant scattering experiments have been carried out on caffeine aqueous solutions as a function of concentration and temperature. The investigation pointed out at the aggregation and solvation properties, particularly at elevated temperatures. Kubo-Anderson theory was used as a framework to investigate the non-coincidence effect (NCE) occurring in the totally symmetric breathing modes of the purine rings, and in the bending modes of the methyl groups of caffeine. The NCE concentration dependence shows that caffeine aggregation at 80 °C occurs by planar stacking of the hydrophobic faces. The data clearly indicate that dipolar interactions determine the reorientational motion of the molecules in solution and are the driving force for the stacking of caffeine. In parallel, the observed dephasing times imply a change in caffeine interactions as a function of temperature and concentration. A decrease, at low water content, of the dephasing time for the ring breathing vibration mode indicates that self-association alters the solvation structure that is detectable at low concentration. These results are in agreement with simulation predictions and serve as an important validation of the models used in those calculations.
Energy Technology Data Exchange (ETDEWEB)
Dorner, B. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France); Baehr, M. [HMI, Berlin (Germany); Petitgrand, D. [Laboratoire Leon Brillouin (LLB) - Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France)
1997-04-01
Using inelastic neutron scattering with polarisation analysis it was possible, for the first time, to observe simultaneously the two magnetic modes split due to dipolar interaction. This would not have been possible with energy resolution only. An analysis of eigenvectors was also performed. (author). 4 refs.
Effect of long- and short-range interactions on the thermodynamics of dipolar spin ice
Energy Technology Data Exchange (ETDEWEB)
Shevchenko, Yuriy, E-mail: shevchenko.ya@dvfu.ru [School of Natural Sciences, Far Eastern Federal University, Vladivostok (Russian Federation); Makarov, Aleksandr, E-mail: makarov.ag@dvfu.ru [School of Natural Sciences, Far Eastern Federal University, Vladivostok (Russian Federation); Nefedev, Konstantin, E-mail: nefedev.kv@dvfu.ru [School of Natural Sciences, Far Eastern Federal University, Vladivostok (Russian Federation); Institute of Applied Mathematics of Far Eastern Branch, Russian Academy of Science, 7 Radio Str, Vladivostok (Russian Federation)
2017-02-05
The thermodynamic properties of dipolar spin ice on square, honeycomb and shakti lattices in the long-range and short-range dipole interaction models are studied. Exact solutions for the density of states, temperature dependencies of heat capacity, and entropy are obtained for these lattices with a finite number of point dipoles by means of complete enumeration. The magnetic susceptibility and average size of the largest low-energy cluster are calculated for square spin ice by means of Wang–Landau and Metropolis methods. We show that the long-range interaction leads to a blurring of the energy spectrum for all considered lattices. The inclusion of the long-range interaction leads to a significant change in the thermodynamic behaviour. An additional peak of heat capacity appears in the case of the honeycomb lattice. The critical temperature shifts in the direction of low or high temperatures; the direction depends on the lattice geometry. The critical temperature of the phase transition of square spin ice in the long-range model with frustrated ground states is obtained with the Wang–Landau and Metropolis methods independently. - Highlights: • The long-range and short-range dipole interaction effects are compared. • Differences are showed for Honeycomb, Shakti and Square spin ice lattices. • The additional heat capacity peaks appear for long-range interaction. • The temperature of heat capacity peak shifts while changing the interaction range.
Remnants of strong tidal interactions
International Nuclear Information System (INIS)
Mcglynn, T.A.
1990-01-01
This paper examines the properties of stellar systems that have recently undergone a strong tidal shock, i.e., a shock which removes a significant fraction of the particles in the system, and where the shocked system has a much smaller mass than the producer of the tidal field. N-body calculations of King models shocked in a variety of ways are performed, and the consequences of the shocks are investigated. The results confirm the prediction of Jaffe for shocked systems. Several models are also run where the tidal forces on the system are constant, simulating a circular orbit around a primary, and the development of tidal radii under these static conditions appears to be a mild process which does not dramatically affect material that is not stripped. The tidal radii are about twice as large as classical formulas would predict. Remnant density profiles are compared with a sample of elliptical galaxies, and the implications of the results for the development of stellar populations and galaxies are considered. 38 refs
On the interplay between hydrodynamic and dipolar particle interactions in suspensions
Gontijo, Rafael Gabler; Cunha, Francisco Ricardo
2017-11-01
The long range nature of particle interactions in the framework of sedimenting suspensions of magnetic particles is discussed. We present new results on the topic, obtained by an in-house code named SIMS. This code solves simultaneously the equations of translational and rotational motion for each magnetic particle in colloidal and non-Brownian suspensions. We use a sophisticated technique of Ewald summations to compute both hydrodynamic and long-range dipolar interactions for force and torque. A brief discussion on the nature of the spatial decays of the sums used to model our multi-body system and the demand for a periodic geometrical representation of the suspension structure is presented. Examples on the calculation of transport properties of colloidal and non-Brownian suspensions of magnetic spheres are presented and validated. Moreover, we discuss how magnetic interactions affects classical transport properties of sedimenting suspensions and also how hydrodynamic interactions modify the micro-structural dynamics of magnetic colloidal suspensions and consenquently the equilibrium magnetization of the so called ferrofluids. The quantitative results are interpreted in terms of the suspension structure evolution in time. The authors wish to aknowledge the following Brazilian research foundations: Fapesp, CNPq and FAPDF.
Sánchez, F. H.; Mendoza Zélis, P.; Arciniegas, M. L.; Pasquevich, G. A.; Fernández van Raap, M. B.
2017-04-01
Aiming to analyze relevant aspects of interacting magnetic nanoparticle systems (frequently called interacting superparamagnets), a model is built from magnetic dipolar interaction and demagnetizing mean-field concepts. By making reasonable simplifying approximations, a simple and useful expression for effective demagnetizing factors is achieved, which allows the analysis of uniform and nonuniform spatial distributions of nanoparticles, in particular the occurrence of clustering. This expression is a function of demagnetizing factors associated with specimen shape and clusters shape, and of the mean distances between near neighbor nanoparticles and between clusters, relative to the characteristic sizes of each of these two types of objects, respectively. The model explains effects of magnetic dipolar interactions, such as the observation of apparent nanoparticle magnetic moments smaller than real ones and approaching to zero as temperature decreases. It is shown that by performing a minimum set of experimental determinations along principal directions of geometrically well-defined specimens, model application allows retrieval of nanoparticle intrinsic properties, like mean volume, magnetic moment, and susceptibility in the absence of interactions. It also permits the estimation of mean interparticle and intercluster relative distances, as well as mean values of demagnetizing factors associated with clusters shape. An expression for average magnetic dipolar energy per nanoparticle is also derived, which is a function of specimen effective demagnetizing factor and magnetization. Experimental test of the model was performed by analysis of results reported in the literature and of original results reported here. The first case corresponds to oleic-acid-coated 8-nm magnetite particles dispersed in PEGDA-600 polymer, and the second one to polyacrilic-acid-coated 13-nm magnetite particles dispersed in PVA solutions from which ferrogels were later produced by a physical
Fluid of hard spheres with dipolar-like patch interaction and effect of adding an isotropic adhesion
2010-01-01
Abstract We compare two fluid models of spherical molecules with anisotropic, purely surface interactions. Both models admit an analytical solution of the molecular Ornstein-Zernike integral equation, within the Percus-Yevick approximation plus orientational linearization. In the first model, the molecular surface corresponds to a unique nonuniform patch, with a potential obtained by truncating a long-ranged dipolar interaction exactly at the contact distance betw...
Chiral-glass transition in a diluted dipolar-interaction Heisenberg system
International Nuclear Information System (INIS)
Zhang Kaicheng; Liu Guibin; Zhu Yan
2011-01-01
Recently, numerical simulations reveal that a spin-glass transition can occur in the three-dimensional diluted dipolar system. By defining the chirality of triple spins in a diluted dipolar Heisenberg spin glass, we study the chiral ordering in the system using parallel tempering algorithm and heat bath method. The finite-size scaling analysis reveals that the system undergoes a chiral-glass transition at finite temperature. - Highlights: → We define the chirality in a diluted dipolar Heisenberg system. → The system undergoes a chiral-glass transition at finite temperature. → We extract the critical exponents of the chiral-glass transition.
Magnetic history dependence of metastable states in thin films with dipolar interactions
International Nuclear Information System (INIS)
Iglesias, Oscar; Labarta, Amilcar
2000-01-01
We present the results of a Monte Carlo simulation of the ground state and magnetic relaxation of a model of a thin film consisting of a two-dimensional square lattice of Heisenberg spins with perpendicular anisotropy K, exchange J and long-range dipolar interactions g. We have studied the ground state configurations of this system for a wide range of the interaction parameters J/g, K/g by means of the simulated annealing procedure, showing that the model is able to reproduce the different magnetic configurations found in real samples. We have found the existence of a certain range of K/g, J/g values for which in-plane and out-of-plane configurations are quasi-degenerated in energy. We show that when a system in this region of parameters is perturbed by an external force that is subsequently removed, different kinds of ordering may be induced depending on the followed procedure. In particular, simulations of relaxations from saturation under an AC demagnetizing field or in zero field are in qualitative agreement with recent experiments on epitaxial and granular alloy thin films, which show a wide variety of magnetic patterns depending on their magnetic history
Van-der-Waals interaction of atoms in dipolar Rydberg states
Kamenski, Aleksandr A.; Mokhnenko, Sergey N.; Ovsiannikov, Vitaly D.
2018-02-01
An asymptotic expression for the van-der-Waals constant C 6( n) ≈ -0.03 n 12 K p ( x) is derived for the long-range interaction between two highly excited hydrogen atoms A and B in their extreme Stark states of equal principal quantum numbers n A = n B = n ≫ 1 and parabolic quantum numbers n 1(2) = n - 1, n 2(1) = m = 0 in the case of collinear orientation of the Stark-state dipolar electric moments and the interatomic axis. The cubic polynomial K 3( x) in powers of reciprocal values of the principal quantum number x = 1/ n and quadratic polynomial K 2( y) in powers of reciprocal values of the principal quantum number squared y = 1/ n 2 were determined on the basis of the standard curve fitting polynomial procedure from the calculated data for C 6( n). The transformation of attractive van-der-Waals force ( C 6 > 0) for low-energy states n observed from the results of numerical calculations based on the second-order perturbation theory for the operator of the long-range interaction between neutral atoms. This transformation is taken into account in the asymptotic formulas (in both cases of p = 2, 3) by polynomials K p tending to unity at n → ∞ ( K p (0) = 1). The transformation from low- n attractive van-der-Waals force into high- n repulsive force demonstrates the gradual increase of the negative contribution to C 6( n) from the lower-energy two-atomic states, of the A(B)-atom principal quantum numbers n'A(B) = n-Δ n (where Δ n = 1, 2, … is significantly smaller than n for the terms providing major contribution to the second-order series), which together with the states of n″B(A) = n+Δ n make the joint contribution proportional to n 12. So, the hydrogen-like manifold structure of the energy spectrum is responsible for the transformation of the power-11 asymptotic dependence C 6( n) ∝ n 11of the low-angular-momenta Rydberg states in many-electron atoms into the power-12 dependence C 6( n) ∝ n 12 for the dipolar states of the Rydberg manifold.
Algebra of strong and electroweak interactions
International Nuclear Information System (INIS)
Bolokhov, S.V.; Vladimirov, Yu.S.
2004-01-01
The algebraic approach to describing the electroweak and strong interactions is considered within the frames of the binary geometrophysics, based on the principles of the Fokker-Feynman direct interparticle interaction theories of the Kaluza-Klein multidimensional geometrical models and the physical structures theory. It is shown that in this approach the electroweak and strong elementary particles interaction through the intermediate vector bosons, are characterized by the subtypes of the algebraic classification of the complex 3 x 3-matrices [ru
Dipolar interactions, molecular flexibility, and flexoelectricity in bent-core liquid crystals.
Dewar, Alastair; Camp, Philip J
2005-11-01
The effects of dipolar interactions and molecular flexibility on the structure and phase behavior of bent-core molecular fluids are studied using Monte Carlo computer simulations. Some calculations of flexoelectric coefficients are also reported. The rigid cores of the model molecules consist of either five or seven soft spheres arranged in a "V" shape with external bend angle gamma. With purely repulsive sphere-sphere interactions and gamma = 0 degrees (linear molecules) the seven-sphere model exhibits isotropic, uniaxial nematic, and untilted and tilted smectic phases. With gamma > or = 20 degrees the untilted smectic phases disappear, while the system with gamma > or = 40 degrees shows a direct tilted smectic-isotropic fluid transition. The addition of electrostatic interactions between transverse dipole moments on the apical spheres is generally seen to reduce the degree of molecular inclination in tilted phases, and destabilizes the nematic and untilted smectic phases of linear molecules. The effects of adding three-segment flexible tails to the ends of five-sphere bent-core molecules are examined using configurational-bias Monte Carlo simulations. Only isotropic and smectic phases are observed. On the one hand, molecular flexibility gives rise to pronounced fluctuations in the smectic-layer structure, bringing the simulated system in better correspondence with real materials; on the other hand, the smectic phase shows almost no tilt. Lastly, the flexoelectric coefficients of various nematic phases--with and without attractive sphere-sphere interactions--are presented. The results are encouraging, but a large computational effort is required to evaluate the appropriate fluctuation relations reliably.
The Charm and Beauty of Strong Interactions
El-Bennich, Bruno
2018-01-01
We briefly review common features and overlapping issues in hadron and flavor physics focussing on continuum QCD approaches to heavy bound states, their mass spectrum and weak decay constants in different strong interaction models.
Including virtual photons in strong interactions
International Nuclear Information System (INIS)
Rusetsky, A.
2003-01-01
In the perturbative field-theoretical models we investigate the inclusion of the electromagnetic interactions into the purely strong theory that describes hadronic processes. In particular, we study the convention for splitting electromagnetic and strong interactions and the ambiguity of such a splitting. The issue of the interpretation of the parameters of the low-energy effective field theory in the presence of electromagnetic interactions is addressed, as well as the scale and gauge dependence of the effective theory couplings. We hope, that the results of these studies are relevant for the electromagnetic sector of ChPT. (orig.)
A theory of the strong interactions
International Nuclear Information System (INIS)
Gross, D.J.
1979-01-01
The most promising candidate for a fundamental microscopic theory of the strong interactions is a gauge theory of colored quarks-Quantum Chromodynamics (QCD). There are many excellent reasons for believing in this theory. It embodies the broken symmetries, SU(3) and chiral SU(3)xSU(3), of the strong interactions and reflects the success of (albeit crude) quark models in explaining the spectrum of the observed hadrons. The hidden quantum number of color, necessary to account for the quantum numbers of the low lying hadrons, plays a fundamental role in this theory as the SU(3) color gauge vector 'gluons' are the mediators of the strong interactions. The absence of physical quark states can be 'explained' by the hypothesis of color confinement i.e. that hadrons are permanently bound in color singlet bound states. Finally this theory is unique in being asymptotically free, thus accounting for the almost free field theory behvior of quarks observed at short distances. (Auth.)
Electroweak and Strong Interactions Phenomenology, Concepts, Models
Scheck, Florian
2012-01-01
Electroweak and Strong Interaction: Phenomenology, Concepts, Models, begins with relativistic quantum mechanics and some quantum field theory which lay the foundation for the rest of the text. The phenomenology and the physics of the fundamental interactions are emphasized through a detailed discussion of the empirical fundamentals of unified theories of strong, electromagnetic, and weak interactions. The principles of local gauge theories are described both in a heuristic and a geometric framework. The minimal standard model of the fundamental interactions is developed in detail and characteristic applications are worked out. Possible signals of physics beyond that model, notably in the physics of neutrinos are also discussed. Among the applications scattering on nucleons and on nuclei provide salient examples. Numerous exercises with solutions make the text suitable for advanced courses or individual study. This completely updated revised new edition contains an enlarged chapter on quantum chromodynamics an...
Rana, Malay Kumar; Chandra, Amalendu
2015-01-21
Atomistic simulations of model nonpolar nanotubes in a Stockmayer liquid are carried out for varying nanotube diameter and nanotube-solvent interactions to investigate solvophobic interactions in generic dipolar solvents. We have considered model armchair type single-walled nonpolar nanotubes with increasing radii from (5,5) to (12,12). The interactions between solute and solvent molecules are modeled by the well-known Lennard-Jones and repulsive Weeks-Chandler-Andersen potentials. We have investigated the density profiles and microscopic arrangement of Stockmayer molecules, orientational profiles of their dipole vectors, time dependence of their occupation, and also the translational and rotational motion of solvent molecules in confined environments of the cylindrical nanopores and also in their external peripheral regions. The present results of structural and dynamical properties of Stockmayer molecules inside and near atomistically rough nonpolar surfaces including their wetting and dewetting behavior for varying interactions provide a more generic picture of solvophobic effects experienced by simple dipolar liquids without any specific interactions such as hydrogen bonds.
International Nuclear Information System (INIS)
Perfetti, E.
2006-11-01
Modelling fluid-rock interactions as well as mixing and unmixing phenomena in geological processes requires robust equations of state (EOS) which must be applicable to systems containing water, gases over a broad range of temperatures and pressures. Cubic equations of state based on the Van der Waals theory (e. g. Soave-Redlich-Kwong or Peng-Robinson) allow simple modelling from the critical parameters of the studied fluid components. However, the accuracy of such equations becomes poor when water is a major component of the fluid since neither association trough hydrogen bonding nor dipolar interactions are accounted for. The Helmholtz energy of a fluid may be written as the sum of different energetic contributions by factorization of partition function. The model developed in this thesis for the pure H 2 O and H 2 S considers three contributions. The first contribution represents the reference Van der Waals fluid which is modelled by the SRK cubic EOS. The second contribution accounts for association through hydrogen bonding and is modelled by a term derived from Cubic Plus Association (CPA) theory. The third contribution corresponds to the dipolar interactions and is modelled by the Mean Spherical Approximation (MSA) theory. The resulting CPAMSA equation has six adjustable parameters, which three represent physical terms whose values are close to their experimental counterpart. This equation results in a better reproduction of the thermodynamic properties of pure water than obtained using the classical CPA equation along the vapour-liquid equilibrium. In addition, extrapolation to higher temperatures and pressure is satisfactory. Similarly, taking into account dipolar interactions together with the SRK cubic equation of state for calculating molar volume of H 2 S as a function of pressure and temperature results in a significant improvement compared to the SRK equation alone. Simple mixing rules between dipolar molecules are proposed to model the H 2 O-H 2 S
Vector mesons in strongly interacting matter
Indian Academy of Sciences (India)
probes like photons, pions or protons or the heated and compressed hadronic matter generated in a heavy-ion collision. Leaving any nuclear medium without strong final-state interactions, dileptons are the optimum decay channel as they avoid any final-state distortion of the 4- momenta of the decay products entering eq.
Vector mesons in strongly interacting matter
Indian Academy of Sciences (India)
Properties of hadrons in strongly interacting matter provide a link between quantum chromodynamics in the ... Top: Spectral function of the ρ-meson at normal nuclear matter density as a function of mass and ... directly but folded with the branching ratio ΓV →p1+p2 /Γtot into the specific final channel one is investigating.
Dipolar quantum gases of erbium
International Nuclear Information System (INIS)
Frisch, A.
2014-01-01
. The corresponding elastic cross section predicted by the theory of universal dipolar scattering scales only with the particle's mass and its magnetic moment and is temperature independent. This represents a dramatic difference compared to non-dipolar fermions, which exhibit a rapidly vanishing elastic cross section at lower temperatures. Another distinctive feature of erbium is its spectrum of Feshbach resonances. Using bosonic erbium we observed an enormous density of resonances exceeding that of alkali metals by at least a factor of ten. We statistically analyzed the spectrum in terms of the random matrix theory and demonstrated that the resonances bare a strong correlation to each other. We identify the origin of this correlation in the highly anisotropic van der Waals interaction potential of erbium. This is a phenomenon not previously encountered in ultracold quantum gases. At the many-body level we observed the d-wave collapse of the Bose-Einstein condensate as previously observed in the chromium experiment in Stuttgart. With the dipolar Fermi gas we demonstrated that the Fermi surface deforms into an ellipsoid induced by the action of the dipole-dipole interaction in momentum space. (author) [de
Thermodynamics of Dipolar Chain Systems
DEFF Research Database (Denmark)
R. Armstrong, J.; Zinner, Nikolaj Thomas; V. Fedorov, D.
2012-01-01
The thermodynamics of a quantum system of layers containing perpendicularly oriented dipolar molecules is studied within an oscillator approximation for both bosonic and fermionic species. The system is assumed to be built from chains with one molecule in each layer. We consider the effects...... numerically. Our findings indicate that thermodynamic observables, such as the heat capacity, can be used to probe the signatures of the intralayer interaction between chains. This should be relevant for near future experiments on polar molecules with strong dipole moments....
Strong interaction studies with kaonic atoms
Directory of Open Access Journals (Sweden)
Marton J.
2016-01-01
Full Text Available The strong interaction of antikaons (K− with nucleons and nuclei in the low-energy regime represents an active research field connected intrinsically with few-body physics. There are important open questions like the question of antikaon nuclear bound states - the prototype system being K−pp. A unique and rather direct experimental access to the antikaon-nucleon scattering lengths is provided by precision X-ray spectroscopy of transitions in low-lying states of light kaonic atoms like kaonic hydrogen isotopes. In the SIDDHARTA experiment at the electron-positron collider DAΦNE of LNF-INFN we measured the most precise values of the strong interaction observables, i.e. the strong interaction on the 1s ground state of the electromagnetically bound K−p atom leading to a hadronic shift ϵ1s and a hadronic broadening Γ1s of the 1s state. The SIDDHARTA result triggered new theoretical work which achieved major progress in the understanding of the low-energy strong interaction with strangeness. Antikaon-nucleon scattering lengths have been calculated constrained by the SIDDHARTA data on kaonic hydrogen. For the extraction of the isospin-dependent scattering lengths a measurement of the hadronic shift and width of kaonic deuterium is necessary. Therefore, new X-ray studies with the focus on kaonic deuterium are in preparation (SIDDHARTA2. Many improvements in the experimental setup will allow to measure kaonic deuterium which is challenging due to the anticipated low X-ray yield. Especially important are the data on the X-ray yields of kaonic deuterium extracted from a exploratory experiment within SIDDHARTA.
Fundamental Structure of Matter and Strong Interaction
Energy Technology Data Exchange (ETDEWEB)
Jian-Ping Chen
2011-11-01
More than 99% of the visible matter in the universe are the protons and neutrons. Their internal structure is mostly governed by the strong interaction. Understanding their internal structure in terms of fundamental degrees-of-freedom is one of the most important subjects in modern physics. Worldwide efforts in the last few decades have lead to numerous surprises and discoveries, but major challenges still remain. An overview of the progress will be presented with a focus on the recent studies of the proton and neutron's electromagnetic and spin structure. Future perspectives will be discussed.
Strong Interaction Studies with PANDA at FAIR
International Nuclear Information System (INIS)
Schönning, Karin
2016-01-01
The Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany, provides unique possibilities for a new generation of nuclear-, hadron- and atomic physics experiments. The future PANDA experiment at FAIR will offer a broad physics programme with emphasis on different aspects of hadron physics. Understanding the strong interaction in the perturbative regime remains one of the greatest challenges in contemporary physics and hadrons provide several important keys. In these proceedings, PANDA will be presented along with some high-lights of the planned physics programme
Strong Interactions Physics at BaBar
Energy Technology Data Exchange (ETDEWEB)
Pioppi, M.
2005-03-14
Recent results obtained by BABAR experiment and related to strong interactions physics are presented, with particular attention to the extraction of the first four hadronic-mass moments and the first three lepton-energy moments in semileptonic decays. From a simultaneous fit to the moments, the CKM element |V{sub cb}|, the inclusive B {yields} X{sub c}lv and other heavy quark parameters are derived. The second topic is the ambiguity-free measurement of cos(2{beta}) in B {yields} J/{Psi}K* decays. With approximately 88 million of B{bar B} pairs, negative solutions for cos(2{beta}) are excluded at 89%.
Strong Interaction Studies with PANDA at FAIR
Schönning, Karin
2016-10-01
The Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany, provides unique possibilities for a new generation of nuclear-, hadron- and atomic physics experiments. The future PANDA experiment at FAIR will offer a broad physics programme with emphasis on different aspects of hadron physics. Understanding the strong interaction in the perturbative regime remains one of the greatest challenges in contemporary physics and hadrons provide several important keys. In these proceedings, PANDA will be presented along with some high-lights of the planned physics programme.
Strong Interactive Massive Particles from a Strong Coupled Theory
DEFF Research Database (Denmark)
Yu. Khlopov, Maxim; Kouvaris, Christoforos
2008-01-01
(-2). These excessive techniparticles are all captured by $^4He$, creating \\emph{techni-O-helium} $tOHe$ ``atoms'', as soon as $^4He$ is formed in Big Bang Nucleosynthesis. The interaction of techni-O-helium with nuclei opens new paths to the creation of heavy nuclei in Big Bang Nucleosynthesis. Due...
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.
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
Muons probe strong hydrogen interactions with defective graphene.
Riccò, Mauro; Pontiroli, Daniele; Mazzani, Marcello; Choucair, Mohammad; Stride, John A; Yazyev, Oleg V
2011-11-09
Here, we present the first muon spectroscopy investigation of graphene, focused on chemically produced, gram-scale samples, appropriate to the large muon penetration depth. We have observed an evident muon spin precession, usually the fingerprint of magnetic order, but here demonstrated to originate from muon-hydrogen nuclear dipolar interactions. This is attributed to the formation of CHMu (analogous to CH(2)) groups, stable up to 1250 K where the signal still persists. The relatively large signal amplitude demonstrates an extraordinary hydrogen capture cross section of CH units. These results also rule out the formation of ferromagnetic or antiferromagnetic order in chemically synthesized graphene samples.
Dynamical Properties of a Diluted Dipolar-Interaction Heisenberg Spin Glass
International Nuclear Information System (INIS)
Zhang Kai-Cheng; Liu Yong; Chi Feng
2014-01-01
Up to now the chirality is seldom studied in the diluted spin glass although many investigations have been performed on the site-ordered Edwards—Anderson model. By simulation, we investigate the dynamical properties of both the spin-glass and the chiral-glass phases in a diluted dipolar system, which was manifested to have a spin-glass transition by recent numerical study. By scaling we find that both phases have the same aging behavior and closer aging parameter μ. Similarly, the domains grow in the same way and both phases have a closer barrier exponent Ψ. It means that both the spins and the chirality have the same dynamical properties and they may freeze at the same temperature. (condensed matter: electronic structure, electrical, magnetic, and optical properties)
Relaxation of an Isolated Dipolar-Interacting Rydberg Quantum Spin System
Orioli, A. Piñeiro; Signoles, A.; Wildhagen, H.; Günter, G.; Berges, J.; Whitlock, S.; Weidemüller, M.
2018-02-01
How do isolated quantum systems approach an equilibrium state? We experimentally and theoretically address this question for a prototypical spin system formed by ultracold atoms prepared in two Rydberg states with different orbital angular momenta. By coupling these states with a resonant microwave driving, we realize a dipolar X Y spin-1 /2 model in an external field. Starting from a spin-polarized state, we suddenly switch on the external field and monitor the subsequent many-body dynamics. Our key observation is density dependent relaxation of the total magnetization much faster than typical decoherence rates. To determine the processes governing this relaxation, we employ different theoretical approaches that treat quantum effects on initial conditions and dynamical laws separately. This allows us to identify an intrinsically quantum component to the relaxation attributed to primordial quantum fluctuations.
Convex Modeling of Interactions with Strong Heredity.
Haris, Asad; Witten, Daniela; Simon, Noah
2016-01-01
We consider the task of fitting a regression model involving interactions among a potentially large set of covariates, in which we wish to enforce strong heredity. We propose FAMILY, a very general framework for this task. Our proposal is a generalization of several existing methods, such as VANISH [Radchenko and James, 2010], hierNet [Bien et al., 2013], the all-pairs lasso, and the lasso using only main effects. It can be formulated as the solution to a convex optimization problem, which we solve using an efficient alternating directions method of multipliers (ADMM) algorithm. This algorithm has guaranteed convergence to the global optimum, can be easily specialized to any convex penalty function of interest, and allows for a straightforward extension to the setting of generalized linear models. We derive an unbiased estimator of the degrees of freedom of FAMILY, and explore its performance in a simulation study and on an HIV sequence data set.
Strongly Interacting Matter at High Energy Density
International Nuclear Information System (INIS)
McLerran, L.
2008-01-01
This lecture concerns the properties of strongly interacting matter (which is described by Quantum Chromodynamics) at very high energy density. I review the properties of matter at high temperature, discussing the deconfinement phase transition. At high baryon density and low temperature, large N c arguments are developed which suggest that high baryonic density matter is a third form of matter, Quarkyonic Matter, that is distinct from confined hadronic matter and deconfined matter. I finally discuss the Color Glass Condensate which controls the high energy limit of QCD, and forms the low x part of a hadron wavefunction. The Glasma is introduced as matter formed by the Color Glass Condensate which eventually thermalizes into a Quark Gluon Plasma
International Nuclear Information System (INIS)
Mamica, S; Krawczyk, M; Lévy, J-C S
2014-01-01
We use a microscopic theory taking into account the dipolar and nearest-neighbour exchange interactions for exploring spin-wave excitations in two-dimensional magnetic dots in the vortex state. Normal modes of different profiles are observed: azimuthal and radial modes, as well as fundamental (quasiuniform) and highly localized modes. We examine the dependence of the frequencies and profiles of these modes on the dipolar-to-exchange interaction ratio and the size of the dot. Special attention is paid to some particular modes, including the lowest mode in the spectrum and the evolution of its profile, and the fundamental mode, the frequency of which proves almost independent of the dipolar-to-exchange interaction ratio. We also provide a selective overview of the experimental, analytical and numerical results from the literature, where different profiles of the lowest mode are reported. We attribute this diversity to the competition between the dipolar and exchange interactions. Finally, we study the hybridization of the modes, show the multi-mode hybridization and explain the selection rules. (paper)
Toward a Strongly Interacting Scalar Higgs Particle
International Nuclear Information System (INIS)
Shalaby, Abouzeid M.; El-Houssieny, M.
2008-01-01
We calculate the vacuum energy of the non-Hermitian and PT symmetric (-gφ 4 ) 2+1 scalar field theory. Rather than the corresponding Hermitian theory and due to the asymptotic freedom property of the theory, the vacuum energy does not blow up for large energy scales which is a good sign to solve the hierarchy problem when using this model to break the U(1)xSU(2) symmetry in the standard model. The theory is strongly interacting and in fact, all the dimensionful parameters in the theory like mass and energy are finite even for very high energy scales. Moreover, relative to the vacuum energy for the Hermitian φ 4 theory, the vacuum energy of the non-Hermitian and PT symmetric (-gφ 4 ) 2+1 theory is tiny, which is a good sign toward the solution of the cosmological constant problem. Remarkably, these features of the non-Hermitian and PT symmetric (-gφ 4 ) 2+1 scalar field theory make it very plausible to be employed as a Higgs mechanism in the standard model instead of the problematic Hermitian Higgs mechanism
Rosenholm, Jarl B
2017-09-01
Specific dipolar, acid-base and charge interactions involve electron displacements. For atoms, single bonds and molecules electron displacement is characterized by electronic potential, absolute hardness, electronegativity and electron gap. In addition, dissociation, bonding, atomization, formation, ionization, affinity and lattice enthalpies are required to quantify the electron displacement in solids. Semiconductors are characterized by valence and conduction band energies, electron gaps and average Fermi energies which in turn determine Galvani potentials of the bulk, space charge layer and surface states. Electron displacement due to interaction between (probe) molecules, liquids and solids are characterized by parameters such as Hamaker constant, solubility parameter, exchange energy density, surface tension, work of adhesion and immersion. They are determined from permittivity, refractive index, enthalpy of vaporization, molar volume, surface pressure and contact angle. Moreover, acidic and basic probes may form adducts which are adsorbed on target substrates in order to establish an indirect measure of polarity, acidity, basicity or hydrogen bonding. Acidic acceptor numbers (AN), basic donor numbers (DN), acidic and basic "electrostatic" (E) and "covalent" (C) parameters determined by enthalpy of adduct formation are considered as general acid-base scales. However, the formal grounds for assignments as dispersive, Lifshitz-van der Waals, polar, acid, base and hydrogen bond interactions are inconsistent. Although correlations are found no of the parameters are mutually fully compatible and moreover the enthalpies of acid-base interaction do not correspond to free energies. In this review the foundations of different acid-base parameters relating to electron displacement within and between (probe) molecules, liquids and (semiconducting) solids are thoroughly investigated and their mutual relationships are evaluated. Copyright © 2017 Elsevier B.V. All rights
De Sitter vacua of strongly interacting QFT
Energy Technology Data Exchange (ETDEWEB)
Buchel, Alex [Department of Applied Mathematics, University of Western Ontario,London, Ontario N6A 5B7 (Canada); Department of Physics and Astronomy, University of Western Ontario,London, Ontario N6A 5B7 (Canada); Perimeter Institute for Theoretical Physics,Waterloo, Ontario N2J 2W9 (Canada); Karapetyan, Aleksandr [Department of Applied Mathematics, University of Western Ontario,London, Ontario N6A 5B7 (Canada)
2017-03-22
We use holographic correspondence to argue that Euclidean (Bunch-Davies) vacuum is a late-time attractor of the dynamical evolution of quantum gauge theories at strong coupling. The Bunch-Davies vacuum is not an adiabatic state, if the gauge theory is non-conformal — the comoving entropy production rate is nonzero. Using the N=2{sup ∗} gauge theory holography, we explore prospects of explaining current accelerated expansion of the Universe as due to the vacuum energy of a strongly coupled QFT.
Relativistic rapprochement of electromagnetic and strong interactions
International Nuclear Information System (INIS)
Strel'tsov, V.N.
1995-01-01
On the basis of the Lienard-Wiechert potential and the relativistic Yukawa potential it is shown that the corresponding interactions with velocity growth increase differently (the electromagnetic one increases faster). According to preliminary estimations they are equivalent, at distances of the 'action radius' of nuclear forces, at γ≅ 960, where γ is the Lorentz factor. 2 refs
"Strong interaction" for particle physics laboratories
2003-01-01
A new Web site pooling the communications resources of particle physics centres all over the world has just been launched. The official launching of the new particle physics website Interactions.org during the Lepton-Proton 2003 Conference at the American laboratory Fermilab was accompanied by music and a flurry of balloons. On the initiative of Fermilab, the site was created by a collaboration of communication teams from over fifteen of the world's particle physics laboratories, including KEK, SLAC, INFN, JINR and, of course, CERN, who pooled their efforts to develop the new tool. The spectacular launching of the new particle physics website Interactions.org at Fermilab on 12 August 2003. A real gateway to particle physics, the site not only contains all the latest news from the laboratories but also offers images, graphics and a video/animation link. In addition, it provides information about scientific policies, links to the universities, a very useful detailed glossary of particle physics and astrophysic...
Supersymmetry and weak, electromagnetic and strong interactions
International Nuclear Information System (INIS)
Fayet, P.
1977-01-01
A supersymmetric theory of particle interactions is discussed. It is based on the earlier model which involves gauge (or vector) superfields, and matter (or chiral) superfields; each of them describes a vector and a Majorana spinor in the first case, or a two-component Dirac spinor and a complex scalar in the second case. The new theory suggests the possible existence of spin - 1/2 gluons and heavy spin-0 quarks, besides spin - 1 gluons and spin - 1/2 quarks. To prevent scalar particles to be exchanged in processes such as μ or β decays a new class of leptons with its own quantum number is introduced; it includes charged leptons and a ''photonic neutrino''
Cross-correlated relaxation rates between protein backbone H–X dipolar interactions
Energy Technology Data Exchange (ETDEWEB)
Vögeli, Beat, E-mail: beat.vogeli@ucdenver.edu [University of Colorado Denver, Department of Biochemistry and Molecular Genetics (United States)
2017-03-15
The relaxation interference between dipole–dipole interactions of two separate spin pairs carries structural and dynamics information. In particular, when compared to individual dynamic behavior of those spin pairs, such cross-correlated relaxation (CCR) rates report on the correlation between the spin pairs. We have recently mapped out correlated motion along the backbone of the protein GB3, using CCR rates among and between consecutive H{sup N}–N and H{sup α}–C{sup α} dipole–dipole interactions. Here, we provide a detailed account of the measurement of the four types of CCR rates. All rates were obtained from at least two different pulse sequences, of which the yet unpublished ones are presented. Detailed comparisons between the different methods and corrections for unwanted pathways demonstrate that the averaged CCR rates are highly accurate and precise with errors of 1.5–3% of the entire value ranges.
Cross-correlated relaxation rates between protein backbone H–X dipolar interactions
International Nuclear Information System (INIS)
Vögeli, Beat
2017-01-01
The relaxation interference between dipole–dipole interactions of two separate spin pairs carries structural and dynamics information. In particular, when compared to individual dynamic behavior of those spin pairs, such cross-correlated relaxation (CCR) rates report on the correlation between the spin pairs. We have recently mapped out correlated motion along the backbone of the protein GB3, using CCR rates among and between consecutive H N –N and H α –C α dipole–dipole interactions. Here, we provide a detailed account of the measurement of the four types of CCR rates. All rates were obtained from at least two different pulse sequences, of which the yet unpublished ones are presented. Detailed comparisons between the different methods and corrections for unwanted pathways demonstrate that the averaged CCR rates are highly accurate and precise with errors of 1.5–3% of the entire value ranges.
QCD : the theory of strong interactions Conference MT17
2001-01-01
The theory of strong interactions,Quantum Chromodynamics (QCD), predicts that the strong interaction is transmitted by the exchange of particles called gluons. Unlike the messengers of electromagnetism photons, which are electrically neutral - gluons carry a strong charge associated with the interaction they mediate. QCD predicts that the strength of the interaction between quarks and gluons becomes weaker at higher energies. LEP has measured the evolution of the strong coupling constant up to energies of 200 GeV and has confirmed this prediction.
Branquinho, Luis C.; Carrião, Marcus S.; Costa, Anderson S.; Zufelato, Nicholas; Sousa, Marcelo H.; Miotto, Ronei; Ivkov, Robert; Bakuzis, Andris F.
2013-01-01
Nanostructured magnetic systems have many applications, including potential use in cancer therapy deriving from their ability to heat in alternating magnetic fields. In this work we explore the influence of particle chain formation on the normalized heating properties, or specific loss power (SLP) of both low- (spherical) and high- (parallelepiped) anisotropy ferrite-based magnetic fluids. Analysis of ferromagnetic resonance (FMR) data shows that high particle concentrations correlate with increasing chain length producing decreasing SLP. Monte Carlo simulations corroborate the FMR results. We propose a theoretical model describing dipole interactions valid for the linear response regime to explain the observed trends. This model predicts optimum particle sizes for hyperthermia to about 30% smaller than those previously predicted, depending on the nanoparticle parameters and chain size. Also, optimum chain lengths depended on nanoparticle surface-to-surface distance. Our results might have important implications to cancer treatment and could motivate new strategies to optimize magnetic hyperthermia. PMID:24096272
Energy Technology Data Exchange (ETDEWEB)
Perez Alcazar, G.A., E-mail: gpgeperez@gmail.com [Departamento de Fisica, Universidad del Valle, A. A. 25360, Cali (Colombia); Unidad Asociada ICMM-IMA, Apdo. 155, 28230 Las Rozas, Madrid (Spain); Zamora, L.E. [Departamento de Fisica, Universidad del Valle, A. A. 25360, Cali (Colombia); Unidad Asociada ICMM-IMA, Apdo. 155, 28230 Las Rozas, Madrid (Spain); Tabares, J.A.; Piamba, J.F. [Departamento de Fisica, Universidad del Valle, A. A. 25360, Cali (Colombia); Gonzalez, J.M. [Unidad Asociada ICMM-IMA, Apdo. 155, 28230 Las Rozas, Madrid (Spain); Greneche, J.M. [LUNAM, Universite du Maine, Institut des Molecules et Materiaux du Mans, UMR CNRS 6283, 72085 Le Mans Cedex 9 (France); Martinez, A. [Instituto de Magnetismo Aplicado, P.O. Box 155, 28230 Las Rozas (Spain); Romero, J.J. [Instituto de Ceramica y Vidrio, CSIC, C/Kelsen 5, 28049, Madrid (Spain); Marco, J.F. [Instituto de Quimica Fisica Rocasolano, CSIC, C/Serrano 119, 28006 Madrid (Spain)
2013-02-15
Powders of melted disordered Fe{sub 50}Mn{sub 10}Al{sub 40} alloy were separated at different mean particle sizes as well as magnetically and structurally characterized. All the samples are BCC and show the same nanostructure. Particles larger than 250 {mu}m showed a lamellar shape compared to smaller particles, which exhibited a more regular form. All the samples are ferromagnetic at room temperature and showed reentrant spin-glass (RSG) and superparamagnetic (SP)-like behaviors between 30 and 60 K and 265 and > 280 K, respectively, as a function of frequency and particle size. The freezing temperature increases with increasing particle size while the blocking one decreases with particle size. The origin of these magnetic phenomena relies in the internal disordered character of samples and the competitive interaction of Fe and Mn atoms. The increase of their critical freezing temperature with increasing mean particle size is due to the increase of the magnetic dipolar interaction between the magnetic moment of each particle with the field produced by the other magnetic moments of their surrounding particles. - Highlights: Black-Right-Pointing-Pointer The effect of particle size in microsized powders of Fe{sub 50}Mn{sub 10}Al{sub 40} melted disordered alloy is studied. Black-Right-Pointing-Pointer Dipolar magnetic interaction between particles exists and this changes with the particle size. Black-Right-Pointing-Pointer For all the particle sizes the reentrant spin- glass and the superparamagnetic-like phases exist. Black-Right-Pointing-Pointer RSG and SP critical temperatures increase with increasing the dipolar magnetic interaction (the mean particle size).
QCD : the theory of strong interactions Exhibition LEPFest 2000
2000-01-01
The theory of strong interactions,Quantum Chromodynamics (QCD),predicts that the strong interac- tion is transmitted by the exchange of particles called glu- ons.Unlike the messengers of electromagnetism -pho- tons,which are electrically neutral -gluons carry a strong charge associated with the interaction they mediate. QCD predicts that the strength of the interaction between quarks and gluons becomes weaker at higher energies.LEP has measured the evolution of the strong coupling constant up to energies of 200 GeV and has confirmed this prediction.
Dipolar collisions of polar molecules in the quantum regime.
Ni, K-K; Ospelkaus, S; Wang, D; Quéméner, G; Neyenhuis, B; de Miranda, M H G; Bohn, J L; Ye, J; Jin, D S
2010-04-29
Ultracold polar molecules offer the possibility of exploring quantum gases with interparticle interactions that are strong, long-range and spatially anisotropic. This is in stark contrast to the much studied dilute gases of ultracold atoms, which have isotropic and extremely short-range (or 'contact') interactions. Furthermore, the large electric dipole moment of polar molecules can be tuned using an external electric field; this has a range of applications such as the control of ultracold chemical reactions, the design of a platform for quantum information processing and the realization of novel quantum many-body systems. Despite intense experimental efforts aimed at observing the influence of dipoles on ultracold molecules, only recently have sufficiently high densities been achieved. Here we report the experimental observation of dipolar collisions in an ultracold molecular gas prepared close to quantum degeneracy. For modest values of an applied electric field, we observe a pronounced increase in the loss rate of fermionic potassium-rubidium molecules due to ultracold chemical reactions. We find that the loss rate has a steep power-law dependence on the induced electric dipole moment, and we show that this dependence can be understood in a relatively simple model based on quantum threshold laws for the scattering of fermionic polar molecules. In addition, we directly observe the spatial anisotropy of the dipolar interaction through measurements of the thermodynamics of the dipolar gas. These results demonstrate how the long-range dipolar interaction can be used for electric-field control of chemical reaction rates in an ultracold gas of polar molecules. Furthermore, the large loss rates in an applied electric field suggest that creating a long-lived ensemble of ultracold polar molecules may require confinement in a two-dimensional trap geometry to suppress the influence of the attractive, 'head-to-tail', dipolar interactions.
Zwierlein, Martin
2017-04-01
Strongly interacting fermions govern physics at all length scales, from nuclear matter to modern electronic materials and neutron stars. The interplay of the Pauli principle with strong interactions can give rise to exotic properties that we do not understand even at a qualitative level. In recent years, ultracold Fermi gases of atoms have emerged as a new type of strongly interacting fermionic matter that can be created and studied in the laboratory with exquisite control. Feshbach resonances allow for unitarity limited interactions, leading to scale invariance, universal thermodynamics and a superfluid phase transition already at 17 Trapped in optical lattices, fermionic atoms realize the Fermi-Hubbard model, believed to capture the essence of cuprate high-temperature superconductors. Here, a microscope allows for single-atom, single-site resolved detection of density and spin correlations, revealing the Pauli hole as well as anti-ferromagnetic and doublon-hole correlations. Novel states of matter are predicted for fermions interacting via long-range dipolar interactions. As an intriguing candidate we created stable fermionic molecules of NaK at ultralow temperatures featuring large dipole moments and second-long spin coherence times. In some of the above examples the experiment outperformed the most advanced computer simulations of many-fermion systems, giving hope for a new level of understanding of strongly interacting fermions.
Prospects for strong interaction physics at ISABELLE. [Seven papers
Energy Technology Data Exchange (ETDEWEB)
Sidhu, D P; Trueman, T L
1977-01-01
Seven papers are presented resulting from a conference intended to stimulate thinking about how ISABELLE could be used for studying strong interactions. A separate abstract was prepared for each paper for inclusion in DOE Energy Research Abstracts (ERA). (PMA)
Strongly-Interacting Fermi Gases in Reduced Dimensions
2015-11-16
superconductivity), nuclear physics (nuclear matter), high - energy physics (effective theories of the strong interactions ), astrophysics (compact stellar objects...strongly- interacting Fermi gases confined in a standing- wave CO2 laser trap. This trap produces a periodic quasi-two-dimensional pancake geometry...predictions of the phase diagram and high temperature superfluidity. Our recent measurements reveal that pairing energy and cloud profiles can be
Dipolar particles in a double-trap confinement: Response to tilting the dipolar orientation
Bjerlin, J.; Bengtsson, J.; Deuretzbacher, F.; Kristinsdóttir, L. H.; Reimann, S. M.
2018-02-01
We analyze the microscopic few-body properties of dipolar particles confined in two parallel quasi-one-dimensional harmonic traps. In particular, we show that an adiabatic rotation of the dipole orientation about the trap axes can drive an initially nonlocalized few-fermion state into a localized state with strong intertrap pairing. With an instant, nonadiabatic rotation, however, localization is inhibited and a highly excited state is reached. This state may be interpreted as the few-body analog of a super-Tonks-Girardeau state, known from one-dimensional systems with contact interactions.
Quark imprisonment as the origin of strong interactions
Amati, Daniele
1974-01-01
A formal scheme is suggested in which the only dynamical ingredients are weak and electro-magnetic interactions with quarks and leptons treated on the same footing. Strong interactions are generated by the requirement that quarks do not appear physically. (7 refs).
Storek, Michael; Jeffrey, Kenneth R; Böhmer, Roland
2014-01-01
NMR echo techniques have proven to be important to study dynamics in ion conductors and other solid materials. Using the spin-3/2 nucleus (7)Li as a probe, both the quadrupolar and the often neglected homonuclear dipolar interactions modulate the NMR frequency as the ion performs jump processes. Retaining only the local-field term of the many-body Hamiltonian, the impact of the dipolar interaction on various echo experiments was studied using spin dynamics calculations yielding products of dipolar and quadrupolar correlation functions. Using a simple stochastic model these functions were simulated with particular emphasis on the impact of ionic motions and on the conditions under which the dipolar and quadrupolar contributions factorize. The results of the computations and of the random-walk simulations are compared with experimental data obtained for various lithium borate and lithium borophosphate glasses. It is concluded that the local-field approximation is a useful means of treating the Li-Li dipole interactions and that the simple model that we introduce is capable of describing many experimentally observed features. Furthermore, because the dipolar and quadrupolar contributions essentially factorize, a selective determination of the corresponding correlation functions becomes possible. Copyright © 2014 Elsevier Inc. All rights reserved.
Semicalssical quantization of interacting anyons in a strong magnetic field
International Nuclear Information System (INIS)
Levit, S.; Sivan, N.
1992-01-01
We represent a semiclassical theory of charged interacting anyons in strong magnetic fields. We apply this theory to a number of few anyons systems including two interacting anyons in the presence of an impurity and three interacting anyons. We discuss the dependence of their energy levels on the statistical parameter and find regions in which this dependence follows very different patterns. The semiclassical arguments allow to correlate these patterns with the change in the character of the classical motion of the system. (author)
Membrane-mediated interaction between strongly anisotropic protein scaffolds.
Directory of Open Access Journals (Sweden)
Yonatan Schweitzer
2015-02-01
Full Text Available Specialized proteins serve as scaffolds sculpting strongly curved membranes of intracellular organelles. Effective membrane shaping requires segregation of these proteins into domains and is, therefore, critically dependent on the protein-protein interaction. Interactions mediated by membrane elastic deformations have been extensively analyzed within approximations of large inter-protein distances, small extents of the protein-mediated membrane bending and small deviations of the protein shapes from isotropic spherical segments. At the same time, important classes of the realistic membrane-shaping proteins have strongly elongated shapes with large and highly anisotropic curvature. Here we investigated, computationally, the membrane mediated interaction between proteins or protein oligomers representing membrane scaffolds with strongly anisotropic curvature, and addressed, quantitatively, a specific case of the scaffold geometrical parameters characterizing BAR domains, which are crucial for membrane shaping in endocytosis. In addition to the previously analyzed contributions to the interaction, we considered a repulsive force stemming from the entropy of the scaffold orientation. We computed this interaction to be of the same order of magnitude as the well-known attractive force related to the entropy of membrane undulations. We demonstrated the scaffold shape anisotropy to cause a mutual aligning of the scaffolds and to generate a strong attractive interaction bringing the scaffolds close to each other to equilibrium distances much smaller than the scaffold size. We computed the energy of interaction between scaffolds of a realistic geometry to constitute tens of kBT, which guarantees a robust segregation of the scaffolds into domains.
Schröder, Leif; Schmitz, Christian; Bachert, Peter
2004-12-01
Proton NMR resonances of the endogenous metabolites creatine and phosphocreatine ((P)Cr), taurine (Tau), and carnosine (Cs, β-alanyl- L-histidine) were studied with regard to residual dipolar couplings and molecular mobility. We present an analysis of the direct 1H- 1H interaction that provides information on motional reorientation of subgroups in these molecules in vivo. For this purpose, localized 1H NMR experiments were performed on m. gastrocnemius of healthy volunteers using a 1.5-T clinical whole-body MR scanner. We evaluated the observable dipolar coupling strength SD0 ( S = order parameter) of the (P)Cr-methyl triplet and the Tau-methylene doublet by means of the apparent line splitting. These were compared to the dipolar coupling strength of the (P)Cr-methylene doublet. In contrast to the aliphatic protons of (P)Cr and Tau, the aromatic H2 ( δ = 8 ppm) and H4 ( δ = 7 ppm) protons of the imidazole ring of Cs exhibit second-order spectra at 1.5 T. This effect is the consequence of incomplete transition from Zeeman to Paschen-Back regime and allows a determination of SD0 from H2 and H4 of Cs as an alternative to evaluating the multiplet splitting which can be measured directly in high-resolution 1H NMR spectra. Experimental data showed striking differences in the mobility of the metabolites when the dipolar coupling constant D0 (calculated with the internuclear distance known from molecular geometry in the case of complete absence of molecular dynamics and motion) is used for comparison. The aliphatic signals involve very small order parameters S ≈ (1.4 - 3) × 10 -4 indicating rapid reorientation of the corresponding subgroups in these metabolites. In contrast, analysis of the Cs resonances yielded S ≈ (113 - 137) × 10 -4. Thus, the immobilization of the Cs imidazole ring owing to an anisotropic cellular substructure in human m. gastrocnemius is much more effective than for (P)Cr and Tau subgroups. Furthermore, 1H NMR experiments on aqueous model
Mixtures of Strongly Interacting Bosons in Optical Lattices
International Nuclear Information System (INIS)
Buonsante, P.; Penna, V.; Giampaolo, S. M.; Illuminati, F.; Vezzani, A.
2008-01-01
We investigate the properties of strongly interacting heteronuclear boson-boson mixtures loaded in realistic optical lattices, with particular emphasis on the physics of interfaces. In particular, we numerically reproduce the recent experimental observation that the addition of a small fraction of 41 K induces a significant loss of coherence in 87 Rb, providing a simple explanation. We then investigate the robustness against the inhomogeneity typical of realistic experimental realizations of the glassy quantum emulsions recently predicted to occur in strongly interacting boson-boson mixtures on ideal homogeneous lattices
Glassy states in fermionic systems with strong disorder and interactions
Schwab, David J.; Chakravarty, Sudip
2009-03-01
We study the competition between interactions and disorder in two dimensions. Whereas a noninteracting system is always Anderson localized by disorder in two dimensions, a pure system can develop a Mott gap for sufficiently strong interactions. Within a simple model, with short-ranged repulsive interactions, we show that, even in the limit of strong interaction, the Mott gap is completely washed out by disorder for an infinite system for dimensions D≤2 , leading to a glassy state. Moreover, the Mott insulator cannot maintain a broken symmetry in the presence of disorder. We then show that the probability of a nonzero gap as a function of system size falls onto a universal curve, reflecting the glassy dynamics. An analytic calculation is also presented in one dimension that provides further insight into the nature of slow dynamics.
New results on strong-interaction effects in antiprotonic hydrogen
Gotta, D; Augsburger, M A; Borchert, G L; Castelli, C M; Chatellard, D; El-Khoury, P; Egger, J P; Gorke, H; Hauser, P R; Indelicato, P J; Kirch, K; Lenz, S; Nelms, N; Rashid, K; Schult, O W B; Siems, T; Simons, L M
1999-01-01
Lyman and Balmer transitions of antiprotonic hydrogen and deuterium have been measured at the low-energy antiproton ring LEAR at CERN in order to determine the strong interaction effects. The X-rays were detected using charge-coupled devices (CCDs) and a reflection type crystal spectrometer. The results of the measurements support the meson-exchange models describing the medium and long range part of the nucleon-antinucleon interaction. (33 refs).
New results on strong-interaction effects in antiprotonic hydrogen
International Nuclear Information System (INIS)
Anagnostopoulos, D. F.; Augsburger, M.; Borchert, G.; Castelli, C.; Chatellard, D.; El-Khoury, P.; Egger, J.-P.; Gorke, H.; Gotta, D.; Hauser, P.; Indelicato, P.; Kirch, K.; Lenz, S.; Nelms, N.; Rashid, K.; Schult, O. W. B.; Siems, Th.; Simons, L. M.
1999-01-01
Lyman and Balmer transitions of antiprotonic hydrogen and deuterium have been measured at the Low-Energy Antiproton Ring LEAR at CERN in order to determine the strong interaction effects. The X-rays were detected using Charge-Coupled Devices (CCDs) and a reflection type crystal spectrometer. The results of the measurements support the meson-exchange models describing the medium and long range part of the nucleon-antinucleon interaction
Vortices of a rotating two-component dipolar Bose–Einstein condensate in an optical lattice
Energy Technology Data Exchange (ETDEWEB)
Wang, Lin-Xue [College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070 (China); Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi' an 710600 (China); Dong, Biao; Chen, Guang-Ping [Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi' an 710600 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Han, Wei; Zhang, Shou-Gang [Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi' an 710600 (China); Shi, Yu-Ren, E-mail: shiyr@nwnu.edu.cn [College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070 (China); Zhang, Xiao-Fei, E-mail: xfzhang@ntsc.ac.cn [Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi' an 710600 (China)
2016-01-28
We consider a two-component Bose–Einstein condensate, which consists of both dipolar and scalar bosonic atoms, in a confinement that is composed of a harmonic oscillator and an underlying optical lattice set rotation. When the dipoles are polarized along the symmetry axis of the harmonic potential, the ground-state density distributions of such a system are investigated as a function of the relative strength between the dipolar and contact interactions, and of the rotation frequency. Our results show that the number of vortices and its related vortex structures of such a system depend strongly on such system parameters. The special two-component system considered here opens up alternate ways for exploring the rich physics of dipolar quantum gases. - Highlights: • Only one component possesses dipole moment. • Spin-dependent optical lattices support exotic vortex structures. • Both the dipole–dipole interaction and rotation frequency are discussed in detail.
Dipolar magnetism in ordered and disordered low-dimensional nanoparticle assemblies
DEFF Research Database (Denmark)
Varón, M.; Beleggia, M; Kasama, T
2013-01-01
Magnetostatic (dipolar) interactions between nanoparticles promise to open new ways to design nanocrystalline magnetic materials and devices if the collective magnetic properties can be controlled at the nanoparticle level. Magnetic dipolar interactions are sufficiently strong to sustain magnetic...... order at ambient temperature in assemblies of closely-spaced nanoparticles with magnetic moments of ≥ 100 μ(B). Here we use electron holography with sub-particle resolution to reveal the correlation between particle arrangement and magnetic order in self-assembled 1D and quasi-2D arrangements of 15 nm...... cobalt nanoparticles. In the initial states, we observe dipolar ferromagnetism, antiferromagnetism and local flux closure, depending on the particle arrangement. Surprisingly, after magnetic saturation, measurements and numerical simulations show that overall ferromagnetic order exists in the present...
Acousto-exciton interaction in a gas of 2D indirect dipolar excitons in the presence of disorder
Energy Technology Data Exchange (ETDEWEB)
Kovalev, V. M.; Chaplik, A. V., E-mail: chaplik@isp.nsc.ru [Russian Academy of Sciences, Rzhanov Institute of Semiconductor Physics, Siberian Branch (Russian Federation)
2016-03-15
A theory for the linear and quadratic responses of a 2D gas of indirect dipolar excitons to an external surface acoustic wave perturbation in the presence of a static random potential is considered. The theory is constructed both for high temperatures, definitely greater than the exciton gas condensation temperature, and at zero temperature by taking into account the Bose–Einstein condensation effects. The particle Green functions, the density–density correlation function, and the quadratic response function are calculated by the “cross” diagram technique. The results obtained are used to calculate the absorption of Rayleigh surface waves and the acoustic exciton gas drag by a Rayleigh wave. The damping of Bogoliubov excitations in an exciton condensate due to theirs scattering by a random potential has also been determined.
Strong light-matter interaction in graphene - Invited talk
DEFF Research Database (Denmark)
Xiao, Sanshui
of graphene with noble-metal nanostructures is currently being explored for strong light-graphene interaction. We introduce a novel hybrid graphene-metal system for studying light-matter interactions with gold-void nanostructures exhibiting resonances in the visible range[1]. The hybrid system is further......Graphene has attracted lots of attention due to its remarkable electronic and optical properties, thus providing great promise in photonics and optoelectronics. However, the performance of these devices is generally limited by the weak light-matter interaction in graphene. The combination...
Discriminative deep inelastic tests of strong interaction field theories
International Nuclear Information System (INIS)
Glueck, M.; Reya, E.
1979-02-01
It is demonstrated that recent measurements of ∫ 0 1 F 2 (x, Q 2 )dx eliminate already all strong interaction field theories except QCD. A detailed study of scaling violations of F 2 (x, Q 2 ) in QCD shows their insensitivity to the gluon content of the hadron at presently measured values of Q 2 . (orig.) [de
Strongly interacting mesoscopic systems of anyons in one dimension
DEFF Research Database (Denmark)
Zinner, N. T.
2015-01-01
Using the fractional statistical properties of so-called anyonic particles, we present exact solutions for up to six strongly interacting particles in one-dimensional confinement that interpolate the usual bosonic and fermionic limits. Specifically, we consider two-component mixtures of anyons...
Interplay of Anderson localization and strong interaction in disordered systems
Energy Technology Data Exchange (ETDEWEB)
Henseler, Peter
2010-01-15
We study the interplay of disorder localization and strong local interactions within the Anderson-Hubbard model. Taking into account local Mott-Hubbard physics and static screening of the disorder potential, the system is mapped onto an effective single-particle Anderson model, which is studied within the self-consistent theory of electron localization. For fermions, we find rich nonmonotonic behavior of the localization length {xi}, particularly in two-dimensional systems, including an interaction-induced exponential enhancement of {xi} for small and intermediate disorders and a strong reduction of {xi} due to hopping suppression by strong interactions. In three dimensions, we identify for half filling a Mott-Hubbard-assisted Anderson localized phase existing between the metallic and the Mott-Hubbard-gapped phases. For small U there is re-entrant behavior from the Anderson localized phase to the metallic phase. For bosons, the unrestricted particle occupation number per lattice site yields a monotonic enhancement of {xi} as a function of decreasing interaction, which we assume to persist until the superfluid Bose-Einstein condensate phase is entered. Besides, we study cold atomic gases expanding, by a diffusion process, in a weak random potential. We show that the density-density correlation function of the expanding gas is strongly affected by disorder and we estimate the typical size of a speckle spot, i.e., a region of enhanced or depleted density. Both a Fermi gas and a Bose-Einstein condensate (in a mean-field approach) are considered. (orig.)
Interplay of Anderson localization and strong interaction in disordered systems
International Nuclear Information System (INIS)
Henseler, Peter
2010-01-01
We study the interplay of disorder localization and strong local interactions within the Anderson-Hubbard model. Taking into account local Mott-Hubbard physics and static screening of the disorder potential, the system is mapped onto an effective single-particle Anderson model, which is studied within the self-consistent theory of electron localization. For fermions, we find rich nonmonotonic behavior of the localization length ξ, particularly in two-dimensional systems, including an interaction-induced exponential enhancement of ξ for small and intermediate disorders and a strong reduction of ξ due to hopping suppression by strong interactions. In three dimensions, we identify for half filling a Mott-Hubbard-assisted Anderson localized phase existing between the metallic and the Mott-Hubbard-gapped phases. For small U there is re-entrant behavior from the Anderson localized phase to the metallic phase. For bosons, the unrestricted particle occupation number per lattice site yields a monotonic enhancement of ξ as a function of decreasing interaction, which we assume to persist until the superfluid Bose-Einstein condensate phase is entered. Besides, we study cold atomic gases expanding, by a diffusion process, in a weak random potential. We show that the density-density correlation function of the expanding gas is strongly affected by disorder and we estimate the typical size of a speckle spot, i.e., a region of enhanced or depleted density. Both a Fermi gas and a Bose-Einstein condensate (in a mean-field approach) are considered. (orig.)
A systematic study of the strong interaction with PANDA
Messchendorp, J. G.; Hosaka, A; Khemchandani, K; Nagahiro, H; Nawa, K
2011-01-01
The theory of Quantum Chromo Dynamics (QCD) reproduces the strong interaction at distances much shorter than the size of the nucleon. At larger distance scales, the generation of hadron masses and confinement cannot yet be derived from first principles on basis of QCD. The PANDA experiment at FAIR
Measurement of strong interaction parameters in antiprotonic hydrogen and deuterium
Augsburger, M A; Borchert, G L; Chatellard, D; Egger, J P; El-Khoury, P; Gorke, H; Gotta, D; Hauser, P R; Indelicato, P J; Kirch, K; Lenz, S; Siems, T; Simons, L M
1999-01-01
In the PS207 experiment at CERN, X-rays from antiprotonic hydrogen and deuterium have been measured at low pressure. The strong interaction shift and the broadening of the K/sub alpha / transition in antiprotonic hydrogen were $9 determined. Evidence was found for the individual hyperfine components of the protonium ground state. (7 refs).
Emergence of junction dynamics in a strongly interacting Bose mixture
DEFF Research Database (Denmark)
Barfknecht, Rafael Emilio; Foerster, Angela; Zinner, Nikolaj Thomas
We study the dynamics of a one-dimensional system composed of a bosonic background and one impurity in single- and double-well trapping geometries. In the limit of strong interactions, this system can be modeled by a spin chain where the exchange coefficients are determined by the geometry of the...
Symmetry-protected collisions between strongly interacting photons.
Thompson, Jeff D; Nicholson, Travis L; Liang, Qi-Yu; Cantu, Sergio H; Venkatramani, Aditya V; Choi, Soonwon; Fedorov, Ilya A; Viscor, Daniel; Pohl, Thomas; Lukin, Mikhail D; Vuletić, Vladan
2017-02-09
Realizing robust quantum phenomena in strongly interacting systems is one of the central challenges in modern physical science. Approaches ranging from topological protection to quantum error correction are currently being explored across many different experimental platforms, including electrons in condensed-matter systems, trapped atoms and photons. Although photon-photon interactions are typically negligible in conventional optical media, strong interactions between individual photons have recently been engineered in several systems. Here, using coherent coupling between light and Rydberg excitations in an ultracold atomic gas, we demonstrate a controlled and coherent exchange collision between two photons that is accompanied by a π/2 phase shift. The effect is robust in that the value of the phase shift is determined by the interaction symmetry rather than the precise experimental parameters, and in that it occurs under conditions where photon absorption is minimal. The measured phase shift of 0.48(3)π is in excellent agreement with a theoretical model. These observations open a route to realizing robust single-photon switches and all-optical quantum logic gates, and to exploring novel quantum many-body phenomena with strongly interacting photons.
Finding strongly interacting symmetry breaking at the SSC
International Nuclear Information System (INIS)
Golden, M.
1989-02-01
Pairs of gauge bosons, W and Z, are a probe of the electroweak symmetry-breaking sector, since the numbers of two gauge boson events are much larger in strongly coupled models than weak. The doubly charged channels W + W + and W/sup /minus//W/sup/minus// are cleanest, since they do not suffer from q/bar q/ or gg fusion backgrounds. The like-charged gauge boson events are observable only if the symmetry breaking sector is strongly interacting. 19 refs., 4 figs., 2 tabs
On the strong crack-microcrack interaction problem
Gorelik, M.; Chudnovsky, A.
1992-07-01
The problem of the crack-microcrack interaction is examined with special attention given to the iterative procedure described by Chudnovsky and Kachanov (1983), Chudnovsky et al. (1984), and Horii and Nemat-Nasser (1983), which yields erroneous results as the crack tips become closer (i.e., for strong crack interaction). To understand the source of error, the traction distributions along the microcrack line on the n-th step of iteration representing the exact and asymptotic stress fields are compared. It is shown that the asymptotic solution gives a gross overestimation of the actual traction.
Ruling out a strongly interacting standard Higgs model
International Nuclear Information System (INIS)
Riesselmann, K.; Willenbrock, S.
1997-01-01
Previous work has suggested that perturbation theory is unreliable for Higgs- and Goldstone-boson scattering, at energies above the Higgs-boson mass, for relatively small values of the Higgs quartic coupling λ(μ). By performing a summation of nonlogarithmic terms, we show that perturbation theory is in fact reliable up to relatively large coupling. This eliminates the possibility of a strongly interacting standard Higgs model at energies above the Higgs-boson mass, complementing earlier studies which excluded strong interactions at energies near the Higgs-boson mass. The summation can be formulated in terms of an appropriate scale in the running coupling, μ=√(s)/e∼√(s)/2.7, so it can be incorporated easily in renormalization-group-improved tree-level amplitudes as well as higher-order calculations. copyright 1996 The American Physical Society
A connection between the strong and weak interactions
International Nuclear Information System (INIS)
Treiman, S.B.
1989-01-01
By studying weak scattering reactions (such as pion-nucleon scattering), the author and his colleague Marvin L Goldberger became renowned in the 1950s for work on dispersion relations. As a result of their collaboration a remarkable and unexpected connection was found between strong and weak interaction quantities. Agreement with experiment was good. Work by others found the same result, but via the partially conserved axial reactor current relation between the axial current divergence and the canonical pion field. (UK)
Thermodynamics of strong-interaction matter from Lattice QCD
Ding, Heng-Tong; Karsch, Frithjof; Mukherjee, Swagato
2015-01-01
We review results from lattice QCD calculations on the thermodynamics of strong-interaction matter with emphasis on input these calculations can provide to the exploration of the phase diagram and properties of hot and dense matter created in heavy ion experiments. This review is organized as follows: 1) Introduction, 2) QCD thermodynamics on the lattice, 3) QCD phase diagram at high temperature, 4) Bulk thermodynamics, 5) Fluctuations of conserved charges, 6) Transport properties, 7) Open he...
Energy Technology Data Exchange (ETDEWEB)
Finley, Adam J.; Matt, Sean P., E-mail: af472@exeter.ac.uk [University of Exeter (UK), Department of Physics and Astronomy, Stoker Road, Devon, Exeter, EX4 4QL (United Kingdom)
2017-08-10
Cool stars with outer convective envelopes are observed to have magnetic fields with a variety of geometries, which on large scales are dominated by a combination of the lowest-order fields such as the dipole, quadrupole, and octupole modes. Magnetized stellar wind outflows are primarily responsible for the loss of angular momentum from these objects during the main sequence. Previous works have shown the reduced effectiveness of the stellar wind braking mechanism with increasingly complex but singular magnetic field geometries. In this paper, we quantify the impact of mixed dipolar and quadrupolar fields on the spin-down torque using 50 MHD simulations with mixed fields, along with 10 each of the pure geometries. The simulated winds include a wide range of magnetic field strength and reside in the slow-rotator regime. We find that the stellar wind braking torque from our combined geometry cases is well described by a broken power-law behavior, where the torque scaling with field strength can be predicted by the dipole component alone or the quadrupolar scaling utilizing the total field strength. The simulation results can be scaled and apply to all main-sequence cool stars. For solar parameters, the lowest-order component of the field (dipole in this paper) is the most significant in determining the angular momentum loss.
Fragmented-condensate solid of dipolar excitons
Andreev, S. V.
2017-05-01
We discuss a possible link between the recently observed macroscopic ordering of ultracold dipolar excitons (MOES) and the phenomenon of supersolidity. In the dilute limit we predict a stable supersolid state for a quasi-one-dimensional system of bosonic dipoles characterized by two- and three-body contact repulsion. We phenomenologically extend our theory to the strongly-correlated regime and find a critical value of the contact interaction parameter at which the supersolid exhibits a quantum phase transition to a fragmented state. The wavelength of the fragmented-condensate solid is defined by the balance between the quantum pressure and the entropy due to fluctuations of the relative phases between the fragments. Our model appears to be in good agreement with the relevant experimental data, including the very recent results on commensurability effect and wavelength of the MOES.
The Electron-Phonon Interaction in Strongly Correlated Systems
International Nuclear Information System (INIS)
Castellani, C.; Grilli, M.
1995-01-01
We analyze the effect of strong electron-electron repulsion on the electron-phonon interaction from a Fermi-liquid point of view and show that the electron-electron interaction is responsible for vertex corrections, which generically lead to a strong suppression of the electron-phonon coupling in the v F q/ω >>1 region, while such effect is not present when v F q/ω F is the Fermi velocity and q and ω are the transferred momentum and frequency respectively. In particular the e-ph scattering is suppressed in transport properties which are dominated by low-energy-high-momentum processes. On the other hand, analyzing the stability criterion for the compressibility, which involves the effective interactions in the dynamical limit, we show that a sizable electron-phonon interaction can push the system towards a phase-separation instability. Finally a detailed analysis of these ideas is carried out using a slave-boson approach for the infinite-U three-band Hubbard model in the presence of a coupling between the local hole density and a dispersionless optical phonon. (author)
Nonperturbative Dynamics of Strong Interactions from Gauge/Gravity Duality
Energy Technology Data Exchange (ETDEWEB)
Grigoryan, Hovhannes [Louisiana State Univ., Baton Rouge, LA (United States)
2008-08-01
This thesis studies important dynamical observables of strong interactions such as form factors. It is known that Quantum Chromodynamics (QCD) is a theory which describes strong interactions. For large energies, one can apply perturbative techniques to solve some of the QCD problems. However, for low energies QCD enters into the nonperturbative regime, where di erent analytical or numerical tools have to be applied to solve problems of strong interactions. The holographic dual model of QCD is such an analytical tool that allows one to solve some nonperturbative QCD problems by translating them into a dual ve-dimensional theory de ned on some warped Anti de Sitter (AdS) background. Working within the framework of the holographic dual model of QCD, we develop a formalism to calculate form factors and wave functions of vector mesons and pions. As a result, we provide predictions of the electric radius, the magnetic and quadrupole moments which can be directly veri ed in lattice calculations or even experimentally. To nd the anomalous pion form factor, we propose an extension of the holographic model by including the Chern-Simons term required to reproduce the chiral anomaly of QCD. This allows us to nd the slope of the form factor with one real and one slightly o -shell photon which appeared to be close to the experimental ndings. We also analyze the limit of large virtualities (when the photon is far o -shell) and establish that predictions of the holographic model analytically coincide with those of perturbative QCD with asymptotic pion distribution amplitude. We also study the e ects of higher dimensional terms in the AdS/QCD model and show that these terms improve the holographic description towards a more realistic scenario. We show this by calculating corrections to the vector meson form factors and corrections to the observables such as electric radii, magnetic and quadrupole moments.
The hadronic standard model for strong and electroweak interactions
Energy Technology Data Exchange (ETDEWEB)
Raczka, R. [Soltan Inst. for Nuclear Studies, Otwock-Swierk (Poland)
1993-12-31
We propose a new model for strong and electro-weak interactions. First, we review various QCD predictions for hadron-hadron and lepton-hadron processes. We indicate that the present formulation of strong interactions in the frame work of Quantum Chromodynamics encounters serious conceptual and numerical difficulties in a reliable description of hadron-hadron and lepton-hadron interactions. Next we propose to replace the strong sector of Standard Model based on unobserved quarks and gluons by the strong sector based on the set of the observed baryons and mesons determined by the spontaneously broken SU(6) gauge field theory model. We analyse various properties of this model such as asymptotic freedom, Reggeization of gauge bosons and fundamental fermions, baryon-baryon and meson-baryon high energy scattering, generation of {Lambda}-polarization in inclusive processes and others. Finally we extend this model by electro-weak sector. We demonstrate a remarkable lepton and hadron anomaly cancellation and we analyse a series of important lepton-hadron and hadron-hadron processes such as e{sup +} + e{sup -} {yields} hadrons, e{sup +} + e{sup -} {yields} W{sup +} + W{sup -}, e{sup +} + e{sup -} {yields} p + anti-p, e + p {yields} e + p and p + anti-p {yields} p + anti-p processes. We obtained a series of interesting new predictions in this model especially for processes with polarized particles. We estimated the value of the strong coupling constant {alpha}(M{sub z}) and we predicted the top baryon mass M{sub {Lambda}{sub t}} {approx_equal} 240 GeV. Since in our model the proton, neutron, {Lambda}-particles, vector mesons like {rho}, {omega}, {phi}, J/{psi} ect. and leptons are elementary most of experimentally analysed lepton-hadron and hadron-hadron processes in LEP1, LEP2, LEAR, HERA, HERMES, LHC and SSC experiments may be relatively easily analysed in our model. (author). 252 refs, 65 figs, 1 tab.
Emergence of junction dynamics in a strongly interacting Bose mixture
DEFF Research Database (Denmark)
Barfknecht, Rafael Emilio; Foerster, Angela; Zinner, Nikolaj Thomas
We study the dynamics of a one-dimensional system composed of a bosonic background and one impurity in single- and double-well trapping geometries. In the limit of strong interactions, this system can be modeled by a spin chain where the exchange coefficients are determined by the geometry...... of the trap. We observe non-trivial dynamics when the repulsion between the impurity and the background is dominant. In this regime, the system exhibits oscillations that resemble the dynamics of a Josephson junction. Furthermore, the double-well geometry allows for an enhancement in the tunneling as compared...
Strongly modified plasmon-matter interaction with mesoscopic quantum emitters
DEFF Research Database (Denmark)
Andersen, Mads Lykke; Stobbe, Søren; Søndberg Sørensen, Anders
2011-01-01
Semiconductor quantum dots (QDs) provide useful means to couple light and matter in applications such as light-harvesting1, 2 and all-solid-state quantum information processing3, 4. This coupling can be increased by placing QDs in nanostructured optical environments such as photonic crystals...... or metallic nanostructures that enable strong confinement of light and thereby enhance the light–matter interaction. It has thus far been assumed that QDs can be described in the same way as atomic photon emitters—as point sources with wavefunctions whose spatial extent can be disregarded. Here we demonstrate...
Strongly interacting atom lasers in three-dimensional optical lattices.
Hen, Itay; Rigol, Marcos
2010-10-29
We show that the dynamical melting of a Mott insulator in a three-dimensional lattice leads to condensation at nonzero momenta, a phenomenon that can be used to generate strongly interacting atom lasers in optical lattices. For infinite on-site repulsion, the case considered here, the momenta at which bosons condense are determined analytically and found to have a simple dependence on the hopping amplitudes. The occupation of the condensates is shown to scale linearly with the total number of atoms in the initial Mott insulator. Our results are obtained by using a Gutzwiller-type mean-field approach, gauged against exact-diagonalization solutions of small systems.
Ising models of strongly coupled biological networks with multivariate interactions
Merchan, Lina; Nemenman, Ilya
2013-03-01
Biological networks consist of a large number of variables that can be coupled by complex multivariate interactions. However, several neuroscience and cell biology experiments have reported that observed statistics of network states can be approximated surprisingly well by maximum entropy models that constrain correlations only within pairs of variables. We would like to verify if this reduction in complexity results from intricacies of biological organization, or if it is a more general attribute of these networks. We generate random networks with p-spin (p > 2) interactions, with N spins and M interaction terms. The probability distribution of the network states is then calculated and approximated with a maximum entropy model based on constraining pairwise spin correlations. Depending on the M/N ratio and the strength of the interaction terms, we observe a transition where the pairwise approximation is very good to a region where it fails. This resembles the sat-unsat transition in constraint satisfaction problems. We argue that the pairwise model works when the number of highly probable states is small. We argue that many biological systems must operate in a strongly constrained regime, and hence we expect the pairwise approximation to be accurate for a wide class of problems. This research has been partially supported by the James S McDonnell Foundation grant No.220020321.
Energy Technology Data Exchange (ETDEWEB)
Spizzo, F., E-mail: spizzo@fe.infn.it [Dipartimento di Fisica e Scienze della Terra and CNISM, Università di Ferrara, I-44122 Ferrara (Italy); Tamisari, M. [Dipartimento di Fisica e Scienze della Terra and CNISM, Università di Ferrara, I-44122 Ferrara (Italy); Dipartimento di Fisica e Geologia and CNISM, Università di Perugia, I-06123 Perugia (Italy); Chinni, F.; Bonfiglioli, E. [Dipartimento di Fisica e Scienze della Terra and CNISM, Università di Ferrara, I-44122 Ferrara (Italy); Gerardino, A. [Istituto di Fotonica e Nanotecnologie, CNR, I-00156 Roma (Italy); Barucca, G. [Dipartimento SIMAU, Università Politecnica delle Marche, I-60131 Ancona (Italy); Bisero, D.; Fin, S.; Del Bianco, L. [Dipartimento di Fisica e Scienze della Terra and CNISM, Università di Ferrara, I-44122 Ferrara (Italy)
2016-02-15
We studied the exchange bias effect in an array of IrMn(3 nm)/NiFe(3 nm) circular dots (size ~140 nm and center-to-center distance ~200 nm, as revealed by microscopy analyses), prepared on a large area (3×3 mm{sup 2}) by electron beam lithography and lift-off, using dc sputtering deposition. Hysteresis loops were measured by SQUID magnetometer at increasing values of temperature T (in the 5–300 K range) after cooling from 300 K down to 5 K in zero field (ZFC mode) and in a saturating magnetic field (FC mode). The exchange bias effect disappears above T~200 K and, at each temperature, the exchange field H{sub EX} measured in ZFC is substantially lower than the FC one. Micromagnetic calculations indicate that, at room temperature, each dot is in high-remanence ground state, but magnetic dipolar interactions establish a low-remanence configuration of the array as a whole. Hence, at low temperature, following the ZFC procedure, the exchange anisotropy in the dot array is averaged out, tending to zero. However, even the FC values of H{sub EX} and of the coercivity H{sub C} are definitely smaller compared to those measured in a reference continuous film with the same stack configuration (at T=5 K, H{sub EX}~90 Oe and H{sub C}~180 Oe in the dots and H{sub EX}~1270 Oe and H{sub C}~860 Oe in the film). Our explanation is based on the proven glassy magnetic nature of the ultrathin IrMn layer, implying the existence of magnetic correlations among the spins, culminating in a collective freezing below T~100 K. We propose, also by the light of micromagnetic simulations, that the small dot size imposes a spatial constraint on the magnetic correlation length among the IrMn spins so that, even at the lowest temperature, their thermal stability, especially at the dot border, is compromised. - Highlights: • Exchange bias in 140 nm-sized IrMn(3 nm)/NiFe(3 nm) dots much weaker than in a film. • Glassy magnetic nature of the IrMn phase and collective spin freezing at T<100 K
Noise in strong laser-atom interactions: Phase telegraph noise
International Nuclear Information System (INIS)
Eberly, J.H.; Wodkiewicz, K.; Shore, B.W.
1984-01-01
We discuss strong laser-atom interactions that are subjected to jump-type (random telegraph) random-phase noise. Physically, the jumps may arise from laser fluctuations, from collisions of various kinds, or from other external forces. Our discussion is carried out in two stages. First, direct and partially heuristic calculations determine the laser spectrum and also give a third-order differential equation for the average inversion of a two-level atom on resonance. At this stage a number of general features of the interaction are able to be studied easily. The optical analog of motional narrowing, for example, is clearly predicted. Second, we show that the theory of generalized Poisson processes allows laser-atom interactions in the presence of random telegraph noise of all kinds (not only phase noise) to be treated systematically, by means of a master equation first used in the context of quantum optics by Burshtein. We use the Burshtein equation to obtain an exact expression for the two-level atom's steady-state resonance fluorescence spectrum, when the exciting laser exhibits phase telegraph noise. Some comparisons are made with results obtained from other noise models. Detailed treatments of the effects ofmly jumps, or as a model of finite laser bandwidth effects, in which the laser frequency exhibits random jumps. We show that these two types of frequency noise can be distinguished in light-scattering spectra. We also discuss examples which demonstrate both temporal and spectral motional narrowing, nonexponential correlations, and non-Lorentzian spectra. Its exact solubility in finite terms makes the frequency-telegraph noise model an attractive alternative to the white-noise Ornstein-Uhlenbeck frequency noise model which has been previously applied to laser-atom interactions
Kanao, Taro; Suto, Hirofumi; Kudo, Kiwamu; Nagasawa, Tazumi; Mizushima, Koichi; Sato, Rie
2018-01-01
We study the magnetization dynamics of a spin-torque oscillator (STO) and a magnetic dot coupled by a magnetic dipolar field using micromagnetic simulation with the aim of developing a read method in magnetic recording that uses magnetic resonance. We propose an STO with a perpendicularly magnetized free layer and an in-plane-magnetized fixed layer as a suitable STO for this resonance read method. When the oscillation frequency of the STO is near the ferromagnetic resonance (FMR) frequency of the magnetic dot, the oscillation amplitude of the STO decreases because FMR excited in the magnetic dot causes additional dissipation. To estimate the read rate of the resonance read method, we study the transient magnetization dynamics to the coupled oscillation state from an initial state where the STO is in a free-running state and the magnetic dot is in a stationary stable state. The STO shows transient dynamics within a time scale of 1 ns, which means that the STO can perform resonance reading with a response time within this time scale. This response time is shorter when the separation length between the STO and the magnetic dot is shorter, which indicates that the response speed can become faster by increasing the strength of the interaction between the STO and the magnetic dot. Successive reads are demonstrated by moving the STO over an array of magnetic dots.
Towards a unified gauge theory of gravitational and strong interactions
International Nuclear Information System (INIS)
Hehl, F.W.; Sijacki, D.
1980-01-01
The space-time properties of leptons and hadrons is studied and it is found necessary to extend general relativity to the gauge theory based on the four-dimensional affine group. This group translates and deforms the tetrads of the locally Minkowskian space-time. Its conserved currents, momentum, and hypermomentum, act as sources in the two field equations of gravity. A Lagrangian quadratic in torsion and curvature allows for the propagation of two independent gauge fields: translational e-gravity mediated by the tetrad coefficients, and deformational GAMMA-gravity mediated by the connection coefficients. For macroscopic matter e-gravity coincides with general relativity up to the post-Newtonian approximation of fourth order. For microscopic matter GAMMA-gravity represents a strong Yang-Mills type interaction. In the linear approximation, for a static source, a confinement potential is found. (author)
Extreme states of matter in strong interaction physics an introduction
Satz, Helmut
2018-01-01
This book is a course-tested primer on the thermodynamics of strongly interacting matter – a profound and challenging area of both theoretical and experimental modern physics. Analytical and numerical studies of statistical quantum chromodynamics provide the main theoretical tool, while in experiments, high-energy nuclear collisions are the key for extensive laboratory investigations. As such, the field straddles statistical, particle and nuclear physics, both conceptually and in the methods of investigation used. The book addresses, above all, the many young scientists starting their scientific research in this field, providing them with a general, self-contained introduction that highlights the basic concepts and ideas and explains why we do what we do. Much of the book focuses on equilibrium thermodynamics: first it presents simplified phenomenological pictures, leading to critical behavior in hadronic matter and to a quark-hadron phase transition. This is followed by elements of finite temperature latti...
Ion Motion in a Plasma Interacting with Strong Magnetic Fields
International Nuclear Information System (INIS)
Weingarten, A.; Grabowski, C.; Chakrabarti, N.; Maron, Y.; Fruchtmant, A.
1999-01-01
The interaction of a plasma with strong magnetic fields takes place in many laboratory experiments and astrophysical plasmas. Applying a strong magnetic field to the plasma may result in plasma displacement, magnetization, or the formation of instabilities. Important phenomena in plasma, such as the energy transport and the momentum balance, take a different form in each case. We study this interaction in a plasma that carries a short-duration (80-ns) current pulse, generating a magnetic field of up to 17 kG. The evolution of the magnetic field, plasma density, ion velocities, and electric fields are determined before and during the current pulse. The dependence of the plasma limiting current on the plasma density and composition are studied and compared to theoretical models based on the different phenomena. When the plasma collisionality is low, three typical velocities should be taken into consideration: the proton and heavier-ion Alfven velocities (v A p and v A h , respectively) and the EMHD magnetic-field penetration velocity into the plasma (v EMHD ). If both Alfven velocities are larger than v EMHD the plasma is pushed ahead of the magnetic piston and the magnetic field energy is dissipated into ion kinetic energy. If v EMHD is the largest of three velocities, the plasma become magnetized and the ions acquire a small axial momentum only. Different ion species may drift in different directions along the current lines. In this case, the magnetic field energy is probably dissipated into electron thermal energy. When vs > V EMHD > vi, as in the case of one of our experiments, ion mass separation occurs. The protons are pushed ahead of the piston while the heavier-ions become magnetized. Since the plasma electrons are unmagnetized they cannot cross the piston, and the heavy ions are probably charge-neutralized by electrons originating from the cathode that are 'born' magnetized
High-energy strong interactions: from `hard' to `soft'
Ryskin, M. G.; Martin, A. D.; Khoze, V. A.
2011-04-01
We discuss the qualitative features of the recent data on multiparticle production observed at the LHC. The tolerable agreement with Monte Carlos based on LO DGLAP evolution indicates that there is no qualitative difference between `hard' and `soft' interactions; and that a perturbative QCD approach may be extended into the soft domain. However, in order to describe the data, these Monte Carlos need an additional infrared cutoff k min with a value k min ˜2-3 GeV which is not small, and which increases with collider energy. Here we explain the physical origin of the large k min . Using an alternative model which matches the `soft' high-energy hadron interactions smoothly on to perturbative QCD at small x, we demonstrate that this effective cutoff k min is actually due to the strong absorption of low k t partons. The model embodies the main features of the BFKL approach, including the diffusion in transverse momenta, ln k t , and an intercept consistent with resummed next-to-leading log corrections. Moreover, the model uses a two-channel eikonal framework, and includes the contributions from the multi-Pomeron exchange diagrams, both non-enhanced and enhanced. The values of a small number of physically-motivated parameters are chosen to reproduce the available total, elastic and proton dissociation cross section (pre-LHC) data. Predictions are made for the LHC, and the relevance to ultra-high-energy cosmic rays is briefly discussed. The low x inclusive integrated gluon PDF, and the diffractive gluon PDF, are calculated in this framework, using the parameters which describe the high-energy pp and pbar{p} ` soft' data. Comparison with the PDFs obtained from the global parton analyses of deep inelastic and related hard scattering data and from diffractive deep inelastic data looks encouraging.
Theoretical & Experimental Research in Weak, Electromagnetic & Strong Interactions
Energy Technology Data Exchange (ETDEWEB)
Nandi, Satyanarayan [Oklahoma State Univ., Stillwater, OK (United States); Babu, Kaladi [Oklahoma State Univ., Stillwater, OK (United States); Rizatdinova, Flera [Oklahoma State Univ., Stillwater, OK (United States); Khanov, Alexander [Oklahoma State Univ., Stillwater, OK (United States); Haley, Joseph [Oklahoma State Univ., Stillwater, OK (United States)
2015-09-17
The conducted research spans a wide range of topics in the theoretical, experimental and phenomenological aspects of elementary particle interactions. Theory projects involve topics in both the energy frontier and the intensity frontier. The experimental research involves energy frontier with the ATLAS Collaboration at the Large Hadron Collider (LHC). In theoretical research, novel ideas going beyond the Standard Model with strong theoretical motivations were proposed, and their experimental tests at the LHC and forthcoming neutrino facilities were outlined. These efforts fall into the following broad categories: (i) TeV scale new physics models for LHC Run 2, including left-right symmetry and trinification symmetry, (ii) unification of elementary particles and forces, including the unification of gauge and Yukawa interactions, (iii) supersummetry and mechanisms of supersymmetry breaking, (iv) superworld without supersymmetry, (v) general models of extra dimensions, (vi) comparing signals of extra dimensions with those of supersymmetry, (vii) models with mirror quarks and mirror leptons at the TeV scale, (viii) models with singlet quarks and singlet Higgs and their implications for Higgs physics at the LHC, (ix) new models for the dark matter of the universe, (x) lepton flavor violation in Higgs decays, (xi) leptogenesis in radiative models of neutrino masses, (xii) light mediator models of non-standard neutrino interactions, (xiii) anomalous muon decay and short baseline neutrino anomalies, (xiv) baryogenesis linked to nucleon decay, and (xv) a new model for recently observed diboson resonance at the LHC and its other phenomenological implications. The experimental High Energy Physics group has been, and continues to be, a successful and productive contributor to the ATLAS experiment at the LHC. Members of the group performed search for gluinos decaying to stop and top quarks, new heavy gauge bosons decaying to top and bottom quarks, and vector-like quarks
Peptide-microgel interactions in the strong coupling regime.
Hansson, Per; Bysell, Helena; Månsson, Ronja; Malmsten, Martin
2012-09-06
The interaction between lightly cross-linked poly(acrylic acid) microgels and oppositely charged peptides was investigated as a function of peptide length, charge density, pH, and salt concentration, with emphasis on the strong coupling regime at high charge contrast. By micromanipulator-assisted light microscopy, the equilibrium volume response of single microgel particles upon oligolysine and oligo(lysine/alanine) absorption could be monitored in a controlled fashion. Results show that microgel deswelling, caused by peptide binding and network neutralization, increases with peptide length (3 attraction between the network chains is described using an exponential force law, and the network elasticity by the inverse Langevin theory. The model was used to calculate the composition of microgels in contact with reservoir solutions of peptides and simple electrolytes. At high electrostatic coupling, the calculated swelling curves were found to display first-order phase transition behavior. The model was demonstrated to capture pH- and electrolyte-dependent microgel swelling, as well as effects of peptide length and charge density on microgel deswelling. The analysis demonstrated that the peptide charge (length), rather than the peptide charge density, determines microgel deswelling. Furthermore, a transition between continuous and discrete network collapse was identified, consistent with experimental results in the present investigations, as well as with results from the literature on microgel deswelling caused by multivalent cations.
Fingering instabilities and pattern formation in a two-component dipolar Bose-Einstein condensate
Xi, Kui-Tian; Byrnes, Tim; Saito, Hiroki
2018-02-01
We study fingering instabilities and pattern formation at the interface of an oppositely polarized two-component Bose-Einstein condensate with strong dipole-dipole interactions in three dimensions. It is shown that the rotational symmetry is spontaneously broken by fingering instability when the dipole-dipole interactions are strengthened. Frog-shaped and mushroom-shaped patterns emerge during the dynamics due to the dipolar interactions. We also demonstrate the spontaneous density modulation and domain growth of a two-component dipolar BEC in the dynamics. Bogoliubov analyses in the two-dimensional approximation are performed, and the characteristic lengths of the domains are estimated analytically. Patterns resembling those in magnetic classical fluids are modulated when the number ratio of atoms, the trap ratio of the external potential, or tilted polarization with respect to the z direction is varied.
Effective Field Theories and Strong Interactions. Final Technical Report
International Nuclear Information System (INIS)
Fleming, Sean
2011-01-01
The framework of Effective Field Theories (EFTs) allows us to describe strong interactions in terms of degrees of freedom relevant to the energy regimes of interest, in the most general way consistent with the symmetries of QCD. Observables are expanded systematically in powers of M lo /M hi , where M lo (M hi ) denotes a low-(high-)energy scale. This organizational principle is referred to as 'power counting'. Terms of increasing powers in the expansion parameter are referred to as leading order (LO), next-to-leading order (NLO), etc. Details of the QCD dynamics not included explicitly are encoded in interaction parameters, or 'low-energy constants' (LECs), which can in principle be calculated from an explicit solution of QCD - for example via lattice simulations- but can also be determined directly from experimental data. QCD has an intrinsic scale M QCD ≅ 1 GeV, at which the QCD coupling constant α s (M QCD ) becomes large and the dynamics becomes non-perturbative. As a consequence M QCD sets the scale for the masses of most hadrons, such as the nucleon mass m N ≅ 940 MeV. EFTs can roughly be divided into two categories: those that can be matched onto QCD in perturbation theory, which we call high-energy EFTs, and those that cannot be matched perturbatively, which we call low-energy EFTs. In high-energy EFTs, M QCD typically sets the low-energy scale, and all the dynamics associated with this scale reside in matrix elements of EFT operators. These non-perturbative matrix elements are the LECs and are also referred to as long-distance contributions. Each matrix element is multiplied by a short-distance coefficient, which contains the dynamics from the high scale M hi . Since M hi >> M QCD , α s (M hi ) hi ∼ M Q , the heavy-quark mass, and in addition to M QCD there are low scales associated with the typical relative momentum ∼ M Q v and energy ∼ M Q v 2 of the heavy quarks. Depending on the sizes of M Q and the heavy-quark velocity v these scales can
Strongly interacting matter at high densities with a soliton model
Johnson, Charles Webster
1998-12-01
One of the major goals of modern nuclear physics is to explore the phase diagram of strongly interacting matter. The study of these 'extreme' conditions is the primary motivation for the construction of the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory which will accelerate nuclei to a center of mass (c.m.) energy of about 200 GeV/nucleon. From a theoretical perspective, a test of quantum chromodynamics (QCD) requires the expansion of the conditions examined from one phase point to the entire phase diagram of strongly-interacting matter. In the present work we focus attention on what happens when the density is increased, at low excitation energies. Experimental results from the Brookhaven Alternating Gradient Synchrotron (AGS) indicate that this regime may be tested in the 'full stopping' (maximum energy deposition) scenario achieved at the AGS having a c.m. collision energy of about 2.5 GeV/nucleon for two equal- mass heavy nuclei. Since the solution of QCD on nuclear length-scales is computationally prohibitive even on today's most powerful computers, progress in the theoretical description of high densities has come through the application of models incorporating some of the essential features of the full theory. The simplest such model is the MIT bag model. We use a significantly more sophisticated model, a nonlocal confining soliton model developed in part at Kent. This model has proven its value in the calculation of the properties of individual mesons and nucleons. In the present application, the many-soliton problem is addressed with the same model. We describe nuclear matter as a lattice of solitons and apply the Wigner-Seitz approximation to the lattice. This means that we consider spherical cells with one soliton centered in each, corresponding to the average properties of the lattice. The average density is then varied by changing the size of the Wigner-Seitz cell. To arrive at a solution, we need to solve a coupled set of
Interaction effects in a microscopic quantum wire model with strong spin-orbit interaction
Winkler, G. W.; Ganahl, M.; Schuricht, D.; Evertz, H. G.; Andergassen, S.
2017-06-01
We investigate the effect of strong interactions on the spectral properties of quantum wires with strong Rashba spin-orbit (SO) interaction in a magnetic field, using a combination of matrix product state and bosonization techniques. Quantum wires with strong Rashba SO interaction and magnetic field exhibit a partial gap in one-half of the conducting modes. Such systems have attracted wide-spread experimental and theoretical attention due to their unusual physical properties, among which are spin-dependent transport, or a topological superconducting phase when under the proximity effect of an s-wave superconductor. As a microscopic model for the quantum wire we study an extended Hubbard model with SO interaction and Zeeman field. We obtain spin resolved spectral densities from the real-time evolution of excitations, and calculate the phase diagram. We find that interactions increase the pseudo gap at k = 0 and thus also enhance the Majorana-supporting phase and stabilize the helical spin order. Furthermore, we calculate the optical conductivity and compare it with the low energy spiral Luttinger liquid result, obtained from field theoretical calculations. With interactions, the optical conductivity is dominated by an excotic excitation of a bound soliton-antisoliton pair known as a breather state. We visualize the oscillating motion of the breather state, which could provide the route to their experimental detection in e.g. cold atom experiments.
The quantum coherence of disordered dipolar bosonic gas
International Nuclear Information System (INIS)
Wang Jiguo; Zhang Aixia; Tang Rongan; Gao Jimin; Xue Jukui
2013-01-01
We investigate the coherence of correlated dipolar gas in the presence of disorder within a three-site Bose–Hubbard model. We show that the interplay between the on-site interaction, the inter-site dipole–dipole interactions (DDI) and the disorder exhibits new and interesting coherence characters that cannot take place in a non-dipolar system. The ratio between the on-site interaction and DDI plays a dominant role in the phase coherence. The resonance character of the coherence against both disorder and interactions emerges. DDI can enhance the coherence at certain values of the disorder and on-site interaction. In the coherence region, the enhancement of the coherence by disorder in a dipolar system is more significant than that in a non-dipolar system. In particular, the on-site interaction and DDI together can enhance the coherence even in the clean dipolar system (i.e. a dipolar system without disorder). However, without the on-site interaction, disorder, DDI or both together suppress the coherence. Furthermore, the relationship between the coherence and the energy gap and the compressibility of the system is also discussed. (paper)
The colours of strong interaction; L`interaction forte sous toutes ses couleurs
Energy Technology Data Exchange (ETDEWEB)
NONE
1995-12-31
The aim of this session is to draw a consistent framework about the different ways to consider strong interaction. A large part is dedicated to theoretical work and the latest experimental results obtained at the first electron collider HERA are discussed. (A.C.)
Interaction of neutral particles with strong laser fields
Energy Technology Data Exchange (ETDEWEB)
Meuren, Sebastian; Keitel, Christoph H.; Di Piazza, Antonino [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany)
2013-07-01
Since the invention of the laser in the 1960s the experimentally available field strengths have continuously increased. The current peak intensity record is 2 x 10{sup 22} W/cm{sup 2} and next generation facilities such as ELI, HiPER and XCELS plan to reach even intensities of the order of 10{sup 24} W/cm{sup 2}. Thus, modern laser facilities are a clean source for very strong external electromagnetic fields and promise new and interesting high-energy physics experiments. In particular, strong laser fields could be used to test non-linear effects in quantum field theory. Earlier we have investigated how radiative corrections modify the coupling of a charged particle inside a strong plane-wave electromagnetic background field. However, a charged particle couples already at tree level to electromagnetic radiation. Therefore, we have now analyzed how the coupling between neutral particles and radiation is affected by a very strong plane-wave electromagnetic background field, when loop corrections are taken into account. In particular, the case of neutrinos is discussed.
Intensities and strong interaction attenuation of kaonic x-rays
Backenstoss, Gerhard; Koch, H; Povel, H P; Schwitter, A; Tauscher, Ludwig
1974-01-01
Relative intensities of numerous kaonic X-ray transitions have been measured for the elements C, P, S, and Cl, from which level widths due to the strong K-nucleus absorption have been determined. From these and earlier published data, optical potential parameters have been derived and possible consequences on the nuclear matter distribution are discussed. (10 refs).
Universal Behavior of Spin Dipolar Relaxation in Atomic Condensates
Deng, Yuangang; Zhou, Yiquan; Deng, Min; Liu, Qi; Tey, Mengkhoon; Gao, Bo; You, Li
2017-04-01
The dipolar relaxation of atomic spinor condensates is studied in terms of the semi-analytical scattering wave functions by utilizing the quantum-defect theory. At nonzero magnetic fields, inelastic dipolar relaxation of exothermic reaction leads to loss of the atomic population. By tuning the bias field, we find that the dipolar relaxation rate exhibits a universal behavior involving a unique dip and peak structure, different from the commonly referenced result based on the Born or the distortedwave Born approximations. The positions for the dip and the peak are shown to be determined dominantly by the short-range s-wave scattering length and the Van der Waals radius, independent of the dipolar interaction strength of ultracold atoms. This is confirmed by the precision measured dipolar relaxation decay rate for both spin-polarized atomic coherent spin states and twin-Fock states of F = 1 87 Rb BoseEinstein condensates. We observe the dipolar relaxation suppression as predicted by our theory for the large bias field, a feature not previously studied experimentally. Our results implicate the possibility of extracting the short-range scattering length and the Van der Waals dispersion coefficient from spin dipolar decay measurements.
Dynamical fermion mass generation by a strong Yukawa interaction
Czech Academy of Sciences Publication Activity Database
Brauner, Tomáš; Hošek, Jiří
2005-01-01
Roč. 72, č. 4 (2005), 045007 ISSN 0556-2821 R&D Projects: GA MŠk LA 080; GA ČR(CZ) GD202/05/H003 Institutional research plan: CEZ:AV0Z10480505 Keywords : dynamical mass generation * Yukawa interaction Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 4.852, year: 2005
Gauge theories of weak, electromagnetic and strong interactions
International Nuclear Information System (INIS)
Boehm, M.; Joos, H.
1978-05-01
This 10 lectures are devided into the chapters: Phenomenological basis of the quantum chromodynamics, phenomenology of weak interactions, quantum electrodynamics and gauge invariance, from the fermimodel to the quantum flavor dynamics, on the quantum theory of yang-mills-fields, spontaneous symmetry breaking - the Higgs-Kibble-mechanism, the Salam-Weinberg-model, asymptotic freedom, quark confinement and charmonium. (WL) [de
Physics Performance Report for PANDA : Strong Interaction Studies with Antiprotons
Erni, W.; Keshelashvili, I.; Krusche, B.; Steinacher, M.; Heng, Y.; Liu, Z.; Liu, H.; Shen, X.; Wang, O.; Xu, H.; Becker, J.; Feldbauer, F.; Heinsius, F. -H.; Held, T.; Koch, H.; Kopf, B.; Pelizaeus, M.; Schroeder, T.; Steinke, M.; Wiedner, U.; Zhong, J.; Bianconi, A.; Bragadireanu, M.; Pantea, D.; Tudorache, A.; Tudorache, V.; De Napoli, M.; Giacoppo, F.; Raciti, G.; Rapisarda, E.; Sfienti, C.; Bialkowski, E.; Budzanowski, A.; Czech, B.; Kistryn, M.; Kliczewski, S.; Kozela, A.; Kulessa, P.; Pysz, K.; Schaefer, W.; Siudak, R.; Szczurek, A.; Czy. zycki, W.; Domagala, M.; Hawryluk, M.; Lisowski, E.; Lisowski, F.; Wojnar, L.; Gil, D.; Hawranek, P.; Kamys, B.; Kistryn, St.; Korcyl, K.; Krzemien, W.; Magiera, A.; Moskal, P.; Rudy, Z.; Salabura, P.; Smyrski, J.; Wronska, A.; Al-Turany, M.; Augustin, I.; Deppe, H.; Flemming, H.; Gerl, J.; Goetzen, K.; Hohler, R.; Lehmann, D.; Lewandowski, B.; Luehning, J.; Maas, F.; Mishra, D.; Orth, H.; Peters, K.; Saito, T.; Schepers, G.; Schmidt, C. J.; Schmitt, L.; Schwarz, C.; Voss, B.; Wieczorek, P.; Wilms, A.; Brinkmann, K. -T.; Freiesleben, H.; Jaekel, R.; Kliemt, R.; Wuerschig, T.; Zaunick, H. -G.; Abazov, V. M.; Alexeev, G.; Arefiev, A.; Astakhov, V. I.; Barabanov, M. Yu.; Batyunya, B. V.; Davydov, Yu. I.; Dodokhov, V. Kh.; Efremov, A. A.; Fedunov, A. G.; Feshchenko, A. A.; Galoyan, A. S.; Grigoryan, S.; Karmokov, A.; Koshurnikov, E. K.; Kudaev, V. Ch.; Lobanov, V. I.; Lobanov, Yu. Yu.; Makarov, A. F.; Malinina, L. V.; Malyshev, V. L.; Mustafaev, G. A.; Olshevski, A.; . Pasyuk, M. A.; Perevalova, E. A.; Piskun, A. A.; Pocheptsov, T. A.; Pontecorvo, G.; Rodionov, V. K.; Rogov, Yu. N.; Salmin, R. A.; Samartsev, A. G.; Sapozhnikov, M. G.; Shabratova, A.; Shabratova, G. S.; Skachkova, A. N.; Skachkov, N. B.; Strokovsky, E. A.; Suleimanov, M. K.; Teshev, R. Sh.; Tokmenin, V. V.; Uzhinsky, V. V.; Vodopianov, A. S.; Zaporozhets, S. A.; Zhuravlev, N. I.; Zorin, A. G.; Branford, D.; Foehl, K.; Glazier, D.; Watts, D.; Woods, P.; Eyrich, W.; Lehmann, A.; Teufel, A.; Dobbs, S.; Metreveli, Z.; Seth, K.; Tann, B.; Tomaradze, A.; Bettoni, D.; Carassiti, V.; Cecchi, A.; Dalpiaz, P.; Fioravanti, E.; Garzia, I.; Negrini, M.; Savri`e, M.; Stancari, G.; Dulach, B.; Gianotti, P.; Guaraldo, C.; Lucherini, V.; Pace, E.; Bersani, A.; Macri, M.; Marinelli, M.; Parodi, R. F.; Brodski, I.; Doering, W.; Drexler, P.; Dueren, M.; Gagyi-Palffy, Z.; Hayrapetyan, A.; Kotulla, M.; Kuehn, W.; Lange, S.; Liu, M.; Metag, V.; Nanova, M.; Novotny, R.; Salz, C.; Schneider, J.; Schoenmeier, P.; Schubert, R.; Spataro, S.; Stenzel, H.; Strackbein, C.; Thiel, M.; Thoering, U.; Yang, S.; Clarkson, T.; Cowie, E.; Downie, E.; Hill, G.; Hoek, M.; Ireland, D.; Kaiser, R.; Keri, T.; Lehmann, I.; Livingston, K.; Lumsden, S.; MacGregor, D.; McKinnon, B.; Murray, M.; Protopopescu, D.; Rosner, G.; Seitz, B.; Yang, G.; Babai, M.; Biegun, A. K.; Bubak, A.; Guliyev, E.; Suyam Jothi, Vanniarajan; Kavatsyuk, M.; Loehner, H.; Messchendorp, J.; Smit, H.; van der Weele, J. C.; Garcia, F.; Riska, D. -O.; Buescher, M.; Dosdall, R.; Dzhygadlo, R.; Gillitzer, A.; Grunwald, D.; Jha, V.; Kemmerling, G.; Kleines, H.; Lehrach, A.; Maier, R.; Mertens, M.; Ohm, H.; Prasuhn, D.; Randriamalala, T.; Ritman, J.; Roeder, M.; Stockmanns, T.; Wintz, P.; Wuestner, P.; Kisiel, J.; Li, S.; Li, Z.; Sun, Z.; Xu, H.; Fissum, S.; Hansen, K.; Isaksson, L.; Lundin, M.; Schroeder, B.; Achenbach, P.; Mora Espi, M. C.; Pochodzalla, J.; Sanchez, S.; Sanchez-Lorente, A.; Dormenev, V. I.; Fedorov, A. A.; Korzhik, M. V.; Missevitch, O. V.; Balanutsa, V.; Chernetsky, V.; Demekhin, A.; Dolgolenko, A.; Fedorets, P.; Gerasimov, A.; Goryachev, V.; Boukharov, A.; Malyshev, O.; Marishev, I.; Semenov, A.; Hoeppner, C.; Ketzer, B.; Konorov, I.; Mann, A.; Neubert, S.; Paul, S.; Weitzel, Q.; Khoukaz, A.; Rausmann, T.; Taeschner, A.; Wessels, J.; Varma, R.; Baldin, E.; Kotov, K.; Peleganchuk, S.; Tikhonov, Yu.; Boucher, J.; Hennino, T.; Kunne, R.; Ong, S.; Pouthas, J.; Ramstein, B.; Rosier, P.; Sudol, M.; Van de Wiele, J.; Zerguerras, T.; Dmowski, K.; Korzeniewski, R.; Przemyslaw, D.; Slowinski, B.; Boca, G.; Braghieri, A.; Costanza, S.; Fontana, A.; Genova, P.; Lavezzi, L.; Montagna, P.; Rotondi, A.; Belikov, N. I.; Davidenko, A. M.; Derevschikov, A. A.; Goncharenko, Y. M.; Grishin, V. N.; Kachanov, V. A.; Konstantinov, D. A.; Kormilitsin, V. A.; Kravtsov, V. I.; Matulenko, Y. A.; Melnik, Y. M.; Meschanin, A. P.; Minaev, N. G.; Mochalov, V. V.; Morozov, D. A.; Nogach, L. V.; Nurushev, S. B.; Ryazantsev, A. V.; Semenov, P. A.; Soloviev, L. F.; Uzunian, A. V.; Vasiliev, A. N.; Yakutin, A. E.; Baeck, T.; Cederwall, B.; Bargholtz, C.; Geren, L.; Tegner, P. E.; Belostotski, S.; Gavrilov, G.; Itzotov, A.; Kisselev, A.; Kravchenko, P.; Manaenkov, S.; Miklukho, O.; Naryshkin, Y.; Veretennikov, D.; Vikhrov, V.; Zhadanov, A.; Fava, L.; Panzieri, D.; Alberto, D.; Amoroso, A.; Botta, E.; Bressani, T.; Bufalino, S.; Bussa, M. P.; Busso, L.; De Mori, F.; Destefanis, M.; Ferrero, L.; Grasso, A.; Greco, M.; Kugathasan, T.; Maggiora, M.; Marcello, S.; Serbanut, G.; Sosio, S.; Bertini, R.; Calvo, D.; Coli, S.; De Remigis, P.; Feliciello, A.; Filippi, A.; Giraudo, G.; Mazza, G.; Rivetti, A.; Szymanska, K.; Tosello, F.; Wheadon, R.; Morra, O.; Agnello, M.; Iazzi, F.; Szymanska, K.; Birsa, R.; Bradamante, F.; Bressan, A.; Martin, A.; Clement, H.; Ekstroem, C.; Calen, H.; Grape, S.; Hoeistad, B.; Johansson, T.; Kupsc, A.; Marciniewski, P.; Thome, E.; Zlomanczuk, J.; Diaz, J.; Ortiz, A.; Borsuk, S.; Chlopik, A.; Guzik, Z.; Kopec, J.; Kozlowski, T.; Melnychuk, D.; Plominski, M.; Szewinski, J.; Traczyk, K.; Zwieglinski, B.; Buehler, P.; Gruber, A.; Kienle, P.; Marton, J.; Widmann, E.; Zmeskal, J.; Lutz, M. F. M.; Pire, B.; Scholten, O.; Timmermans, R.
To study fundamental questions of hadron and nuclear physics in interactions of antiprotons with nucleons and nuclei, the universal PANDA detector will be built. Gluonic excitations, the physics of strange and charm quarks and nucleon structure studies will be performed with unprecedented accuracy
Coulomb plus strong interaction bound states - momentum space numerical solutions
International Nuclear Information System (INIS)
Heddle, D.P.; Tabakin, F.
1985-01-01
The levels and widths of hadronic atoms are calculated in momentum space using an inverse algorithm for the eigenvalue problem. The Coulomb singularity is handled by the Lande substraction method. Relativistic, nonlocal, complex hadron-nucleus interactions are incorporated as well as vacuum polarization and finite size effects. Coordinate space wavefunctions are obtained by employing a Fourier Bessel transformation. (orig.)
Unconventional States of Matter with Cold Atoms and Dipolar Molecules
2014-08-20
interaction level but not at the kinetic-energy level. We investigate Fermi liquid states of the ultra-cold magnetic dipolar Fermi gases in the...lations” Phys. Rev. Lett. 112, 156403 (2014), 5. Gia-Wei Chern, Congjun Wu, “Four-coloring model and frustrated superfluidity in the dia- mond lattice...interactions”, Sci- entific Report 2, 392 (2012). 18. Yi Li, Congjun Wu, “Spin-orbit coupled Fermi liquid theory with magnetic dipolar interac- tion”, Phys. Rev
Quantum memory with strong and controllable Rydberg-level interactions.
Li, Lin; Kuzmich, A
2016-11-21
Realization of distributed quantum systems requires fast generation and long-term storage of quantum states. Ground atomic states enable memories with storage times in the range of a minute, however their relatively weak interactions do not allow fast creation of non-classical collective states. Rydberg atomic systems feature fast preparation of singly excited collective states and their efficient mapping into light, but storage times in these approaches have not yet exceeded a few microseconds. Here we demonstrate a system that combines fast quantum state generation and long-term storage. An initially prepared coherent state of an atomic memory is transformed into a non-classical collective atomic state by Rydberg-level interactions in less than a microsecond. By sheltering the quantum state in the ground atomic levels, the storage time is increased by almost two orders of magnitude. This advance opens a door to a number of quantum protocols for scalable generation and distribution of entanglement.
Hadron yields and the phase diagram of strongly interacting matter
Floris, Michele
2014-01-01
This paper presents a brief review of the interpretation of measurements of hadron yields in hadronic interactions within the framework of thermal models, over a broad energy range (from SIS to LHC energies, $\\sqrt{s_{NN}} \\simeq$ 2.5 GeV -- 5 TeV). Recent experimental results and theoretical developments are reported, with an emphasis on topics discussed during the Quark Matter 2014 conference.
Theoretical studies in weak, electromagnetic and strong interactions. Attachments
International Nuclear Information System (INIS)
Nandi, S.
1999-01-01
The project covered a wide area of current research in theoretical high-energy physics. This included Standard Model (SM) as well as physics beyond the Standard Model. Specific topics included supersymmetry (SUSY), perturbative quantum chromodynamics (QCD), a new weak interaction for the third family (called topflavor), neutrino masses and mixings, topcolor model, Pade approximation, and its application to perturbative QCD and other physical processes
Interaction of Azobenzene and Benzalaniline with Strong Amido Bases.
Kornev, Alexander N; Sushev, Vyacheslav V; Zolotareva, Natalia V; Baranov, Evgenii V; Fukin, Georgy K; Abakumov, Gleb A
2015-12-18
The interaction of azobenzene with lithium dicyclohexylamide (Cy2NLi) in THF or Et2O afforded the ion-radical salt of azobenzene (1) structurally characterized for the first time and dicyclohexylaminyl radical, which begins a novel chain of transformations leading eventually to the imino-enamido lithium complex (3). Benzalaniline, being a relative of azobenzene, reacted with Cy2NLi without electron transfer by a proton-abstraction mechanism to form the dilithium salt of N(1),N(2),1,2-tetraphenylethene-1,2-diamine quantitatively.
Spin effects in strong-field laser-electron interactions
International Nuclear Information System (INIS)
Ahrens, S; Bauke, H; Müller, T-O; Villalba-Chávez, S; Müller, C
2013-01-01
The electron spin degree of freedom can play a significant role in relativistic scattering processes involving intense laser fields. In this contribution we discuss the influence of the electron spin on (i) Kapitza-Dirac scattering in an x-ray laser field of high intensity, (ii) photo-induced electron-positron pair production in a strong laser wave and (iii) multiphoton electron-positron pair production on an atomic nucleus. We show that in all cases under consideration the electron spin can have a characteristic impact on the process properties and their total probabilities. To this end, spin-resolved calculations based on the Dirac equation in the presence of an intense laser field are performed. The predictions from Dirac theory are also compared with the corresponding results from the Klein-Gordon equation.
Strongly-interacting mirror fermions at the LHC
Directory of Open Access Journals (Sweden)
Triantaphyllou George
2017-01-01
Full Text Available The introduction of mirror fermions corresponding to an interchange of leftwith right-handed fermion quantum numbers of the Standard Model can lead to a model according to which the BEH mechanism is just an effective manifestation of a more fundamental theory while the recently-discovered Higgs-like particle is composite. This is achieved by a non-abelian gauge symmetry encompassing three mirror-fermion families strongly coupled at energies near 1 TeV. The corresponding non-perturbative dynamics lead to dynamical mirror-fermion masses between 0.14 - 1.2 TeV. Furthermore, one expects the formation of composite states, i.e. “mirror mesons”, with masses between 0.1 and 3 TeV. The number and properties of the resulting new degrees of freedom lead to a rich and interesting phenomenology, part of which is analyzed in the present work.
A non-linear theory of strong interactions
International Nuclear Information System (INIS)
Skyrme, T.H.R.
1994-01-01
A non-linear theory of mesons, nucleons and hyperons is proposed. The three independent fields of the usual symmetrical pseudo-scalar pion field are replaced by the three directions of a four-component field vector of constant length, conceived in an Euclidean four-dimensional isotopic spin space. This length provides the universal scaling factor, all other constants being dimensionless; the mass of the meson field is generated by a φ 4 term; this destroys the continuous rotation group in the iso-space, leaving a 'cubic' symmetry group. Classification of states by this group introduces quantum numbers corresponding to isotopic spin and to 'strangeness'; one consequences is that, at least in elementary interactions, charge is only conserved module 4. Furthermore, particle states have not a well-defined parity, but parity is effectively conserved for meson-nucleon interactions. A simplified model, using only two dimensions of space and iso-space, is considered further; the non-linear meson field has solutions with particle character, and an indication is given of the way in which the particle field variables might be introduced as collective co-ordinates describing the dynamics of these particular solutions of the meson field equations, suggesting a unified theory based on the meson field alone. (author). 7 refs
Phase transitions to dipolar clusters and charge density waves in high T{sub c} superconductors
Energy Technology Data Exchange (ETDEWEB)
Saarela, M., E-mail: Mikko.Saarela@oulu.fi [Department of Physics, University of Oulu, P.O. Box 3000, FIN-90014 (Finland); Kusmartsev, F.V. [Department of Physics, Loughborough University, LE11 3TU (United Kingdom)
2017-02-15
We show that doping of hole charge carriers leads to formation of electric dipolar clusters in cuprates. They are created by many-body interactions between the dopant ion outside and holes inside the CuO planes. Because of the two-fold degeneracy holes in the CuO plane cluster into four-particles resonance valence bond plaquettes bound with dopant ions. Such dipoles may order into charge-density waves (CDW) or stripes or form a disordered state depending on doping and temperature. The lowest energy of the ordered system corresponds to a local anti-ferroelectric ordering. The mobility of individual disordered dipoles is very low at low temperatures and they prefer first to bind into dipole-dipole pairs. Electromagnetic radiation interacts strongly with electric dipoles and when the sample is subjected to it the mobility changes significantly. This leads to a fractal growth of dipolar clusters. The existence of electric dipoles and CDW induce two phase transitions with increasing temperature, melting of the ordered state and disappearance of the dipolar state. Ferroelectricity at low doping is a natural consequence of such dipole moments. We develop a theory based on two-level systems and dipole-dipole interaction to explain the behavior of the polarization as a function of temperature and electric field.
Magnetic dynamics of weakly and strongly interacting hematite nanoparticles
DEFF Research Database (Denmark)
Hansen, Mikkel Fougt; Bender Koch, Christian; Mørup, Steen
2000-01-01
The magnetic dynamics of two differently treated samples of hematite nanoparticles from the same batch with a particle size of about 20 nm have been studied by Mossbauer spectroscopy. The dynamics of the first sample, in which the particles are coated and dispersed in water, is in accordance.......3(-0.8)(+1.0) x 10(-10) s for a rotation of the sublattice magnetization directions in the rhombohedral (111) plane. The corresponding median superparamagnetic blocking temperature is about 150 K. The dynamics of the second, dry sample, in which the particles are uncoated and thus allowed to aggregate, is slowed...... down by interparticle interactions and a magnetically split spectrum is retained at room temperature. The temperature variation or the magnetic hyperfine field, corresponding to different quantiles in the hyperfine field distribution, can be consistently described by a mean field model...
Light and neutron scattering study of strongly interacting ionic micelles
International Nuclear Information System (INIS)
Degiorgio, V.; Corti, M.; Piazza, R.
1989-01-01
Dilute solutions of ionic micelles formed by biological glycolipids (gangliosides) have been investigated at various ionic strengths by static and dynamic light scaterring and by small-angle neutron scattering. The size and shape of the micelle is not appreciably affected by the added salt concentration in the range 0-100 mM NaCL. From the measured intensity of scattered light we derive the electric charge Z of the micelle by fitting the data to a theoretical calculation which uses a screened Coulomb potential for the intermicellar interaction, and the hypernetted chain approximation for the calculation of the radial distribution function. The correlation function derived from dynamic light scattering shows the long time contribution typical of concentrated polydisperse systems (author). 15 refs.; 6 figs
Strong delayed interactive effects of metal exposure and warming
DEFF Research Database (Denmark)
Debecker, Sara; Dinh, Khuong Van; Stoks, Robby
2017-01-01
As contaminants are often more toxic at higher temperatures, predicting their impact under global warming remains a key challenge for ecological risk assessment. Ignoring delayed effects, synergistic interactions between contaminants and warming, and differences in sensitivity across species......’ ranges could lead to an important underestimation of the risks. We addressed all three mechanisms by studying effects of larval exposure to zinc and warming before, during, and after metamorphosis in Ischnura elegans damselflies from high- and lowlatitude populations. By integrating these mechanisms...... was especially remarkable in high-latitude animals, as they appeared almost insensitive to zinc during the larval stage. Second, the well-known synergism between metals and warming was manifested not only during the larval stage but also after metamorphosis, yet notably only in low-latitude damselflies...
Natural Cold Baryogenesis from Strongly Interacting Electroweak Symmetry Breaking
Konstandin, Thomas
2011-01-01
The mechanism of "cold electroweak baryogenesis" has been so far unpopular because its proposal has relied on the ad-hoc assumption of a period of hybrid inflation at the electroweak scale with the Higgs acting as the waterfall field. We argue here that cold baryogenesis can be naturally realized without the need to introduce any slow-roll potential. Our point is that composite Higgs models where electroweak symmetry breaking arises via a strongly first-order phase transition provide a well-motivated framework for cold baryogenesis. In this case, reheating proceeds by bubble collisions and we argue that this can induce changes in Chern-Simons number, which in the presence of new sources of CP violation commonly lead to baryogenesis. We illustrate this mechanism using as a source of CP violation an effective dimension-six operator which is free from EDM constraints, another advantage of cold baryogenesis compared to the standard theory of electroweak baryogenesis. Our results are general as they do not rely on...
Exact tensor network ansatz for strongly interacting systems
Zaletel, Michael P.
It appears that the tensor network ansatz, while not quite complete, is an efficient coordinate system for the tiny subset of a many-body Hilbert space which can be realized as a low energy state of a local Hamiltonian. However, we don't fully understand precisely which phases are captured by the tensor network ansatz, how to compute their physical observables (even numerically), or how to compute a tensor network representation for a ground state given a microscopic Hamiltonian. These questions are algorithmic in nature, but their resolution is intimately related to understanding the nature of quantum entanglement in many-body systems. For this reason it is useful to compute the tensor network representation of various `model' wavefunctions representative of different phases of matter; this allows us to understand how the entanglement properties of each phase are expressed in the tensor network ansatz, and can serve as test cases for algorithm development. Condensed matter physics has many illuminating model wavefunctions, such as Laughlin's celebrated wave function for the fractional quantum Hall effect, the Bardeen-Cooper-Schrieffer wave function for superconductivity, and Anderson's resonating valence bond ansatz for spin liquids. This thesis presents some results on exact tensor network representations of these model wavefunctions. In addition, a tensor network representation is given for the time evolution operator of a long-range one-dimensional Hamiltonian, which allows one to numerically simulate the time evolution of power-law interacting spin chains as well as two-dimensional strips and cylinders.
Baez, M. L.; Borzi, R. A.
2017-02-01
We study the three-dimensional Kasteleyn transition in both nearest neighbours and dipolar spin ice models using an algorithm that conserves the number of excitations. We first limit the interactions range to nearest neighbours to test the method in the presence of a field applied along ≤ft[1 0 0\\right] , and then focus on the dipolar spin ice model. The effect of dipolar interactions, which is known to be greatly self screened at zero field, is particularly strong near full polarization. It shifts the Kasteleyn transition to lower temperatures, which decreases ≈0.4 K for the parameters corresponding to the best known spin ice materials, \\text{D}{{\\text{y}}2}\\text{T}{{\\text{i}}2}{{\\text{O}}7} and \\text{H}{{\\text{o}}2}\\text{T}{{\\text{i}}2}{{\\text{O}}7} . This shift implies effective dipolar fields as big as 0.05 T opposing the applied field, and thus favouring the creation of ‘strings’ of reversed spins. We compare the reduction in the transition temperature with results in previous experiments, and study the phenomenon quantitatively using a simple molecular field approach. Finally, we relate the presence of the effective residual field to the appearance of string-ordered phases at low fields and temperatures, and we check numerically that for fields applied along ≤ft[1 0 0\\right] there are only three different stable phases at zero temperature.
Study of the interaction of atoms with strong laser fields
International Nuclear Information System (INIS)
Edwards, M.
1984-01-01
Three aspects of the interactions of atoms with high intensity laser fields were treated. All three were motivated by experiment. The first investigation was prompted by a recent experiment (Kruit et al. 1983) involving multiphoton ionization of Xe. In this experiment it was found that the photoelectron energy spectrum contained peaks that corresponded to the absorption of more than the minimum number of photons required to ionize the atom. A model approximation here showed good qualitative agreement with experiment. An experiment (Grove et al. 1977) designed to test a theoretical calculation of the dynamical Stark effect stimulated the second part of this thesis, namely: a study of how an adiabatically and near-adiabatically changing field intensity affects the resonance fluorescence spectrum of a two-level atom. It was found that there is an asymmetry in the spectrum for off-resonance excitation produced because the field turn-on repopulates the dressed state that is depopulated by spontaneous emission. The third part of this thesis was based on an experiment (Granneman and Van der Wiel 1976) that attempted to verify a perturbation calculation of the two-photon ionization cross section of Cs. A discrepancy of four orders of magnitude near a minimum in the cross section was found between theory and experiment. To explain this discrepancy it was suggested (Armstrong and Beers 1977) that the effective order of nonlinearity (k) for this process varied significantly around the minimum. This study involves a perturbation calculation of k. It was found that k varies rapidly around the minimum, and that this variation should be experimentally observable for laser intensities of the order of tens of GW cm -2
Dimensional Reduction in Quantum Dipolar Antiferromagnets
Babkevich, P.; Jeong, M.; Matsumoto, Y.; Kovacevic, I.; Finco, A.; Toft-Petersen, R.; Ritter, C.; Mânsson, M.; Nakatsuji, S.; Rønnow, H. M.
2016-05-01
We report ac susceptibility, specific heat, and neutron scattering measurements on a dipolar-coupled antiferromagnet LiYbF4 . For the thermal transition, the order-parameter critical exponent is found to be 0.20(1) and the specific-heat critical exponent -0.25 (1 ) . The exponents agree with the 2D X Y /h4 universality class despite the lack of apparent two-dimensionality in the structure. The order-parameter exponent for the quantum phase transitions is found to be 0.35(1) corresponding to (2 +1 )D . These results are in line with those found for LiErF4 which has the same crystal structure, but largely different TN, crystal field environment and hyperfine interactions. Our results therefore experimentally establish that the dimensional reduction is universal to quantum dipolar antiferromagnets on a distorted diamond lattice.
DEFF Research Database (Denmark)
Bellotti, Filipe Furlan; Salami Dehkharghani, Amin; Zinner, Nikolaj Thomas
2017-01-01
We investigate one-dimensional harmonically trapped two-component systems for repulsive interaction strengths ranging from the non-interacting to the strongly interacting regime for Fermi-Fermi mixtures. A new and powerful mapping between the interaction strength parameters from a continuous...
Hyperspherical Treatment of Strongly-Interacting Few-Fermion Systems in One Dimension
DEFF Research Database (Denmark)
Volosniev, A. G.; Fedorov, D. V.; Jensen, A. S.
2015-01-01
We examine a one-dimensional two-component fermionic system in a trap, assuming that all particles have the same mass and interact through a strong repulsive zero-range force. First we show how a simple system of three strongly interacting particles in a harmonic trap can be treated using...
Quantum phases of dipolar soft-core bosons
Grimmer, D.; Safavi-Naini, A.; Capogrosso-Sansone, B.; Söyler, Ş. G.
2014-10-01
We study the phase diagram of a system of soft-core dipolar bosons confined to a two-dimensional optical lattice layer. We assume that dipoles are aligned perpendicular to the layer such that the dipolar interactions are purely repulsive and isotropic. We consider the full dipolar interaction and perform path-integral quantum Monte Carlo simulations using the worm algorithm. Besides a superfluid phase, we find various solid and supersolid phases. We show that, unlike what was found previously for the case of nearest-neighbor interaction, supersolid phases are stabilized by doping the solids not only with particles but with holes as well. We further study the stability of these quantum phases against thermal fluctuations. Finally, we discuss pair formation and the stability of the pair checkerboard phase formed in a bilayer geometry, and we suggest experimental conditions under which the pair checkerboard phase can be observed.
Directory of Open Access Journals (Sweden)
L. Chomaz
2016-11-01
Full Text Available In a joint experimental and theoretical effort, we report on the formation of a macrodroplet state in an ultracold bosonic gas of erbium atoms with strong dipolar interactions. By precise tuning of the s-wave scattering length below the so-called dipolar length, we observe a smooth crossover of the ground state from a dilute Bose-Einstein condensate to a dense macrodroplet state of more than 2×10^{4} atoms. Based on the study of collective excitations and loss features, we prove that quantum fluctuations stabilize the ultracold gas far beyond the instability threshold imposed by mean-field interactions. Finally, we perform expansion measurements, showing that although self-bound solutions are prevented by losses, the interplay between quantum stabilization and losses results in a minimal time-of-flight expansion velocity at a finite scattering length.
Quantum magnetism in strongly interacting one-dimensional spinor Bose systems
DEFF Research Database (Denmark)
Salami Dehkharghani, Amin; Volosniev, A. G.; Lindgren, E. J.
2015-01-01
-range inter-species interactions much larger than their intra-species interactions and show that they have novel energetic and magnetic properties. In the strongly interacting regime, these systems have energies that are fractions of the basic harmonic oscillator trap quantum and have spatially separated...
Coexistence of density wave and superfluid order in a dipolar Fermi gas
DEFF Research Database (Denmark)
Wu, Zhigang; Block, Jens Kusk; Bruun, Georg M.
2015-01-01
We analyse the coexistence of superfluid and density wave (stripe) order in a quasi-two-dimensional gas of dipolar fermions aligned by an external field. Remarkably, the anisotropic nature of the dipolar interaction allows for such a coexistence in a large region of the zero temperature phase...
Equilibrium phases of dipolar lattice bosons in the presence of random diagonal disorder
Zhang, C.; Safavi-Naini, A.; Capogrosso-Sansone, B.
2018-01-01
Ultracold gases offer an unprecedented opportunity to engineer disorder and interactions in a controlled manner. In an effort to understand the interplay between disorder, dipolar interactions, and quantum degeneracy, we study two-dimensional hard-core dipolar lattice bosons in the presence of on-site bound disorder. Our results are based on large-scale path-integral quantum Monte Carlo simulations by the worm algorithm. We study the ground-state phase diagram at a fixed half-integer filling factor for which the clean system is either a superfluid at a lower dipolar interaction strength or a checkerboard solid at a larger dipolar interaction strength. We find that, even for weak dipolar interactions, superfluidity is destroyed in favor of a Bose glass at a relatively low disorder strength. Interestingly, in the presence of disorder, superfluidity persists for values of the dipolar interaction strength for which the clean system is a checkerboard solid. At a fixed disorder strength, as the dipolar interaction is increased, superfluidity is destroyed in favor of a Bose glass. As the interaction is further increased, the system eventually develops extended checkerboard patterns in the density distribution. Due to the presence of disorder, though, grain boundaries and defects, responsible for a finite residual compressibility, are present in the density distribution. Finally, we study the robustness of the superfluid phase against thermal fluctuations.
Effects of interaction imbalance in a strongly repulsive one-dimensional Bose gas
DEFF Research Database (Denmark)
Barfknecht, Rafael Emilio; Zinner, Nikolaj Thomas; Foerster, Angela
2018-01-01
We calculate the spatial distributions and the dynamics of a few-body two-component strongly interacting Bose gas confined to an effectively one-dimensional trapping potential. We describe the densities for each component in the trap for different interaction and population imbalances. We calculate...
Effects of interaction imbalance in a strongly repulsive one-dimensional Bose gas
DEFF Research Database (Denmark)
Barfknecht, Rafael Emilio; Zinner, Nikolaj Thomas; Foerster, Angela
2018-01-01
We calculate the spatial distributions and the dynamics of a few-body two-component strongly interacting Bose gas confined to an effectively one-dimensional trapping potential. We describe the densities for each component in the trap for different interaction and population imbalances. We calcula...
Anisotropic Expansion of a Thermal Dipolar Bose Gas.
Tang, Y; Sykes, A G; Burdick, N Q; DiSciacca, J M; Petrov, D S; Lev, B L
2016-10-07
We report on the anisotropic expansion of ultracold bosonic dysprosium gases at temperatures above quantum degeneracy and develop a quantitative theory to describe this behavior. The theory expresses the postexpansion aspect ratio in terms of temperature and microscopic collisional properties by incorporating Hartree-Fock mean-field interactions, hydrodynamic effects, and Bose-enhancement factors. Our results extend the utility of expansion imaging by providing accurate thermometry for dipolar thermal Bose gases. Furthermore, we present a simple method to determine scattering lengths in dipolar gases, including near a Feshbach resonance, through observation of thermal gas expansion.
Directory of Open Access Journals (Sweden)
Neng-Zhong Xie
Full Text Available Three strong interactions between amino acid side chains (salt bridge, cation-π, and amide bridge are studied that are stronger than (or comparable to the common hydrogen bond interactions, and play important roles in protein-protein interactions.Quantum chemical methods MP2 and CCSD(T are used in calculations of interaction energies and structural optimizations.The energies of three types of amino acid side chain interactions in gaseous phase and in aqueous solutions are calculated using high level quantum chemical methods and basis sets. Typical examples of amino acid salt bridge, cation-π, and amide bridge interactions are analyzed, including the inhibitor design targeting neuraminidase (NA enzyme of influenza A virus, and the ligand binding interactions in the HCV p7 ion channel. The inhibition mechanism of the M2 proton channel in the influenza A virus is analyzed based on strong amino acid interactions.(1 The salt bridge interactions between acidic amino acids (Glu- and Asp- and alkaline amino acids (Arg+, Lys+ and His+ are the strongest residue-residue interactions. However, this type of interaction may be weakened by solvation effects and broken by lower pH conditions. (2 The cation- interactions between protonated amino acids (Arg+, Lys+ and His+ and aromatic amino acids (Phe, Tyr, Trp and His are 2.5 to 5-fold stronger than common hydrogen bond interactions and are less affected by the solvation environment. (3 The amide bridge interactions between the two amide-containing amino acids (Asn and Gln are three times stronger than hydrogen bond interactions, which are less influenced by the pH of the solution. (4 Ten of the twenty natural amino acids are involved in salt bridge, or cation-, or amide bridge interactions that often play important roles in protein-protein, protein-peptide, protein-ligand, and protein-DNA interactions.
Gauge unification of basic forces particularly of gravitation with strong interactions
International Nuclear Information System (INIS)
Salam, A.
1977-01-01
Corresponding to the two known types of gauge theories, Yang-Mills with spin-one mediating particles and Einstein Weyl with spin-two mediating particles, it is speculated that two distinct gauge unifications of the basic forces appear to be taking place. One is the familiar Yang-Mills unification of weak and electromagnetic forces with the strong. The second is the less familiar gauge unification of gravitation with spin-two tensor-dominated aspects of strong interactions. It is proposed that there are strongly interacting spin-two strong gravitons obeying Einstein's equations, and their existence gives a clue to an understanding of the (partial) confinement of quarks, as well as of the concept of hadronic temperature, through the use of Schwarzschild de-Sitter-like partially confining solitonic solutions of the strong gravity Einstein equation
arXiv Recent results from the strong interactions program of NA61/SHINE
Pulawski, Szymon
2017-01-01
The NA61/SHINE experiment studies hadron production in hadron+hadron, hadron+nucleus and nucleus+nucleus collisions. The strong interactions program has two main purposes: study the properties of the onset of deconfinement and search for the signatures of the critical point of strongly interacting matter. This aim is pursued by performing a two-dimensional scan of the phase diagram by varying the energy/momentum (13A-158A GeV/c) and the system size (p+p, Be+Be, Ar+Sc, Xe+La) of the collisions. This publication reviews recent results from p+p, Be+Be and Ar+Sc interactions. Measured particle spectra are discussed and compared to NA49 results from Pb+Pb collisions. The results illustrate the progress towards scanning the phase diagram of strongly interacting matter.
Strong excitonic interactions in the oxygen K-edge of perovskite oxides
Energy Technology Data Exchange (ETDEWEB)
Tomita, Kota; Miyata, Tomohiro [Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505 (Japan); Olovsson, Weine [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping (Sweden); Mizoguchi, Teruyasu, E-mail: teru@iis.u-tokyo.ac.jp [Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505 (Japan)
2017-07-15
Excitonic interactions of the oxygen K-edge electron energy-loss near-edge structure (ELNES) of perovskite oxides, CaTiO{sub 3}, SrTiO{sub 3}, and BaTiO{sub 3}, together with reference oxides, MgO, CaO, SrO, BaO, and TiO{sub 2}, were investigated using a first-principles Bethe–Salpeter equation calculation. Although the transition energy of oxygen K-edge is high, strong excitonic interactions were present in the oxygen K-edge ELNES of the perovskite oxides, whereas the excitonic interactions were negligible in the oxygen K-edge ELNES of the reference compounds. Detailed investigation of the electronic structure suggests that the strong excitonic interaction in the oxygen K-edge ELNES of the perovskite oxides is caused by the directionally confined, low-dimensional electronic structure at the Ti–O–Ti bonds. - Highlights: • Excitonic interaction in oxygen-K edge is investigated. • Strong excitonic interaction is found in the oxygen-K edge of perovskite oxides. • The strong excitonic interaction is ascribed to the low-dimensional and confined electronic structure.
Critical Time Crystals in Dipolar Systems.
Ho, Wen Wei; Choi, Soonwon; Lukin, Mikhail D; Abanin, Dmitry A
2017-07-07
We analyze the quantum dynamics of periodically driven, disordered systems in the presence of long-range interactions. Focusing on the stability of discrete time crystalline (DTC) order in such systems, we use a perturbative procedure to evaluate its lifetime. For 3D systems with dipolar interactions, we show that the corresponding decay is parametrically slow, implying that robust, long-lived DTC order can be obtained. We further predict a sharp crossover from the stable DTC regime into a regime where DTC order is lost, reminiscent of a phase transition. These results are in good agreement with the recent experiments utilizing a dense, dipolar spin ensemble in diamond [Nature (London) 543, 221 (2017)NATUAS0028-083610.1038/nature21426]. They demonstrate the existence of a novel, critical DTC regime that is stabilized not by many-body localization but rather by slow, critical dynamics. Our analysis shows that the DTC response can be used as a sensitive probe of nonequilibrium quantum matter.
Spectral asymptotics of a strong δ′ interaction supported by a surface
International Nuclear Information System (INIS)
Exner, Pavel; Jex, Michal
2014-01-01
Highlights: • Attractive δ ′ interactions supported by a smooth surface are considered. • Surfaces can be either infinite and asymptotically planar, or compact and closed. • Spectral asymptotics is determined by the geometry of the interaction support. - Abstract: We derive asymptotic expansion for the spectrum of Hamiltonians with a strong attractive δ ′ interaction supported by a smooth surface in R 3 , either infinite and asymptotically planar, or compact and closed. Its second term is found to be determined by a Schrödinger type operator with an effective potential expressed in terms of the interaction support curvatures
Energy Technology Data Exchange (ETDEWEB)
Perfetti, E
2006-11-15
Modelling fluid-rock interactions as well as mixing and unmixing phenomena in geological processes requires robust equations of state (EOS) which must be applicable to systems containing water, gases over a broad range of temperatures and pressures. Cubic equations of state based on the Van der Waals theory (e. g. Soave-Redlich-Kwong or Peng-Robinson) allow simple modelling from the critical parameters of the studied fluid components. However, the accuracy of such equations becomes poor when water is a major component of the fluid since neither association trough hydrogen bonding nor dipolar interactions are accounted for. The Helmholtz energy of a fluid may be written as the sum of different energetic contributions by factorization of partition function. The model developed in this thesis for the pure H{sub 2}O and H{sub 2}S considers three contributions. The first contribution represents the reference Van der Waals fluid which is modelled by the SRK cubic EOS. The second contribution accounts for association through hydrogen bonding and is modelled by a term derived from Cubic Plus Association (CPA) theory. The third contribution corresponds to the dipolar interactions and is modelled by the Mean Spherical Approximation (MSA) theory. The resulting CPAMSA equation has six adjustable parameters, which three represent physical terms whose values are close to their experimental counterpart. This equation results in a better reproduction of the thermodynamic properties of pure water than obtained using the classical CPA equation along the vapour-liquid equilibrium. In addition, extrapolation to higher temperatures and pressure is satisfactory. Similarly, taking into account dipolar interactions together with the SRK cubic equation of state for calculating molar volume of H{sub 2}S as a function of pressure and temperature results in a significant improvement compared to the SRK equation alone. Simple mixing rules between dipolar molecules are proposed to model the H
Precision determination of the strong interaction shift and width in pionic hydrogen
International Nuclear Information System (INIS)
Anagnostopoulos, D.F.; Covita, D.D.S.; Santos, J.M.F. dos; Veloso, J.F.C.A.; Fuhrmann, H.; Gruber, A.; Hirtl, A.; Ishiwatari, T.; Marton, J.; Schmid, P.; Zmeskal, J.; Gotta, D.; Hennebach, M.; Nekipelov, M.; Indelicato, P.; Jensen, T.; Bigot, E.O. Le; Trassinelli, M.; Simons, L.M.
2005-01-01
The new pionic hydrogen experiment at PSI aims at an improvement in the determination of the strong interaction ground state shift and width of the pionic hydrogen atom. High precision x-ray crystal spectroscopy is used to extract isospin separated scattering lengths with accuracies on the percent level. Compared to previous efforts, the energy resolution and statistics could be improved considerably and the background is much reduced. The response function of the Johann-type crystal spectrometer has been determined with a novel method with unprecedented accuracy. The inherent difficulties of the exotic atom's method result, from the fact that the formation of a sufficient amount of pionic hydrogen atoms requires a hydrogen target pressure of several bar at least. For the extraction of a strong interaction shift, an extrapolation method to vacuum conditions proved to be successful. This contribution mostly discusses the strategy to extract a result for the strong interaction width from the data.(author)
International Nuclear Information System (INIS)
Chan, J.; DePorcel, L.; Dixon, L.
1997-06-01
This conference explored the role of the strong interaction in the physics of hadrons and partons. The Institute attracted 239 physicists from 16 countries to hear lectures on the underlying theory of Quantum Chromodynamics, modern theoretical calculational techniques, and experimental investigation of the strong interaction as it appears in various phenomena. Different regimes in which one can calculate reliably in QCD were addressed in series of lectures on perturbation theory, lattice gauge theories, and heavy quark expansions. Studies of QCD in hadron-hadron collisions, electron-positron annihilation, and electron-proton collisions all give differing perspectives on the strong interaction--from low-x to high-Q 2 . Experimental understanding of the production and decay of heavy quarks as well as the lighter meson states has continued to evolve over the past years, and these topics were also covered at the School. Selected papers have been indexed separately for inclusion in the Energy Science and Technology Database
Computational strong-field quantum dynamics intense light-matter interactions
2017-01-01
This graduate textbook introduces the computational techniques to study ultra-fast quantum dynamics of matter exposed to strong laser fields. Coverage includes methods to propagate wavefunctions according to the time-dependent Schrödinger, Klein-Gordon or Dirac equation, the calculation of typical observables, time-dependent density functional theory, multi-configurational time-dependent Hartree-Fock, time-dependent configuration interaction singles, the strong-field approximation, and the microscopic particle-in-cell approach.
Computational strong-field quantum dynamics. Intense light-matter interactions
Energy Technology Data Exchange (ETDEWEB)
Bauer, Dieter (ed.) [Rostock Univ. (Germany). Inst. fuer Physik
2017-09-01
This graduate textbook introduces the computational techniques to study ultra-fast quantum dynamics of matter exposed to strong laser fields. Coverage includes methods to propagate wavefunctions according to the time dependent Schroedinger, Klein-Gordon or Dirac equation, the calculation of typical observables, time-dependent density functional theory, multi configurational time-dependent Hartree-Fock, time-dependent configuration interaction singles, the strong-field approximation, and the microscopic particle-in-cell approach.
International Nuclear Information System (INIS)
Drechsler, W.
1977-01-01
A Lagrangian formalism invariant under the gauge group U 1 xUSpsub(2.2) is set up in terms of spinor fields defined on a fiber bundle with Cartan connexion. The fiber of the Cartan bundle over space-time associated with strong interactions is characterized by an elementary length parameter R related to the range of the strong forces, and the structural group USpsub(2.2) of the bundle (being the covering group of the SOsub(4.1) de Sitter group) implies a gauge description of strong interactions based on the noncompact gauge group USpsub(2.2). The U 1 factor in the total gauge group corresponds to the usual gauge formulation for the electromagnetic interactions. The positivity of the energy associated with stable extended one-particle states in this dualistic description of charged hadronic matter immersed in the fiber geometry (this dualism is called strong fiber dynamics (SFD)) requires hadrons to be assigned to representations of the compact subgroup SU 2 xSU 2 of the strong-interaction gauge group USpsub(2.2). A brief discussion of the point-particle limit R→O is given by linking the presented SFD formalism for extended hadrons to an idealized description in terms of operators in a local quantum field theory
Proceedings of Summer Institute of Particle Physics, July 27-August 7, 1981: the strong interactions
Energy Technology Data Exchange (ETDEWEB)
Mosher, A. (ed.)
1982-01-01
The ninth SLAC Summer Institute on Particle Physics was held in the period July 27 to August 7, 1981. The central topic was the strong interactions with the first seven days spent in a pedagogic mode and the last three in a topical conference. In addition to the morning lectures on experimental and theoretical aspects of the strong interactions, three were lectures on machine physics; this year it was electron-positron colliding beam machines, both storage rings and linear colliders. Twenty-three individual items from the meeting were prepared separately for the data base. (GHT)
Strong interaction effects in high-Z K sup minus atoms
Energy Technology Data Exchange (ETDEWEB)
Batty, C.J.; Eckhause, M.; Gall, K.P.; Guss, P.P.; Hertzog, D.W.; Kane, J.R.; Kunselman, A.R.; Miller, J.P.; O' Brien, F.; Phillips, W.C.; Powers, R.J.; Roberts, B.L.; Sutton, R.B.; Vulcan, W.F.; Welsh, R.E.; Whyley, R.J.; Winter, R.G. (Rutherford-Appleton Laboratory, Chilton, Didcot OX11 0QX, United Kingdom (GB) College of William and Mary, Williamsburg, Virginia 23185 Boston University, Boston, Massachusetts 02215 University of Wyoming, Laramie, Wyoming 82071 California Institute of Technology, Pasadena, California 91125 Carnegie-Mellon University, Pittsburgh, Pennsylvania 15213)
1989-11-01
A systematic experimental study of strong interaction shifts, widths, and yields from high-{ital Z} kaonic atoms is reported. Strong interaction effects for the {ital K}{sup {minus}}(8{r arrow}7) transition were measured in U, Pb, and W, and the {ital K}{sup {minus}}(7{r arrow}6) transition in W was also observed. This is the first observation of two measurably broadened and shifted kaonic transitions in a single target and thus permitted the width of the upper state to be determined directly, rather than being inferred from yield data. The results are compared with optical-model calculations.
Marri, Ivan; Govoni, Marco; Ossicini, Stefano
2014-09-24
We present density functional theory calculations of carrier multiplication properties in a system of strongly coupled silicon nanocrystals. Our results suggest that nanocrystal-nanocrystal interaction can lead to a reduction of the carrier multiplication energy threshold without altering the carrier multiplication efficiency at high energies, in agreement with experiments. The time evolution of the number of electron-hole pairs generated in a system of strongly interacting nanocrystals upon absorption of high-energy photons is analyzed by solving a system of coupled rate equations, where exciton recycling mechanisms are implemented. We reconsider the role played by Auger recombination which is here accounted also as an active, nondetrimental process.
Engineering the Dynamics of Effective Spin-Chain Models for Strongly Interacting Atomic Gases
DEFF Research Database (Denmark)
Volosniev, A. G.; Petrosyan, D.; Valiente, M.
2015-01-01
We consider a one-dimensional gas of cold atoms with strong contact interactions and construct an effective spin-chain Hamiltonian for a two-component system. The resulting Heisenberg spin model can be engineered by manipulating the shape of the external confining potential of the atomic gas. We...
Density functional theory for strongly-interacting electrons: Perspectives for Physics and Chemistry
Gori Giorgi, P.; Seidl, M.
2010-01-01
Improving the accuracy and thus broadening the applicability of electronic density functional theory (DFT) is crucial to many research areas, from material science, to theoretical chemistry, biophysics and biochemistry. In the last three years, the mathematical structure of the strong-interaction
Czech Academy of Sciences Publication Activity Database
Exner, Pavel; Pankrashkin, K.
2014-01-01
Roč. 39, č. 2 (2014), s. 193-212 ISSN 0360-5302 R&D Projects: GA ČR GAP203/11/0701 Institutional support: RVO:61389005 Keywords : Eigenvalue * Schrödinger operator * singular interaction * strong coupling * 35Q40 * 35P15 * 35J10 Subject RIV: BE - Theoretical Physics Impact factor: 1.013, year: 2014
Spectral asymptotics of a strong delta ' interaction supported by a surface
Czech Academy of Sciences Publication Activity Database
Exner, Pavel; Jex, M.
2014-01-01
Roč. 378, 30-31 (2014), s. 2091-2095 ISSN 0375-9601 R&D Projects: GA ČR(CZ) GA14-06818S Institutional support: RVO:61389005 Keywords : delta ' surface interaction * strong coupling expansion Subject RIV: BE - Theoretical Physics Impact factor: 1.683, year: 2014
On eigenvalue asymptotics for strong delta-interactions supported by surfaces with boundaries
Czech Academy of Sciences Publication Activity Database
Dittrich, Jaroslav; Exner, Pavel; Kuhn, C.; Pankrashkin, K.
2016-01-01
Roč. 97, 1-2 (2016), s. 1-25 ISSN 0921-7134 R&D Projects: GA ČR(CZ) GA14-06818S Institutional support: RVO:61389005 Keywords : singular Schrodinger operator * delta-interaction * strong coupling * eigenvalue Subject RIV: BE - Theoretical Physics Impact factor: 0.933, year: 2016
Fractional energy states of strongly-interacting bosons in one dimension
DEFF Research Database (Denmark)
Zinner, Nikolaj Thomas; G. Volosniev, A.; V. Fedorov, D.
2014-01-01
We study two-component bosonic systems with strong inter-species and vanishing intra-species interactions. A new class of exact eigenstates is found with energies that are {\\it not} sums of the single-particle energies with wave functions that have the characteristic feature that they vanish over...
Flavor changing strong interaction effects on top quark physics at the CERN LHC
International Nuclear Information System (INIS)
Ferreira, P.M.; Santos, R.; Oliveira, O.
2006-01-01
We perform a model independent analysis of the flavor changing strong interaction vertices relevant to the LHC. In particular, the contribution of dimension six operators to single top production in various production processes is discussed, together with possible hints for identifying signals and setting bounds on physics beyond the standard model
Interaction of a neutral composite particle with a strong Coulomb field
International Nuclear Information System (INIS)
Wong, Cheuk-Yin.
1988-01-01
The author discusses the interaction of the quasi-composite (e/sup /plus//e/sup /minus//) system with an external electromagnetic field. This problem addresses the question of the origin of strong positron lines in quasi-elastic heavy-ion reactions. 3 refs
Description of meson strong and electromagnetic interactions in quantum chiral theory
International Nuclear Information System (INIS)
Volkov, M.K.; Pervushin, V.N.
1978-01-01
Strong and electromagnetic interactions of mesons in the framework of the chiral theory are considered. The pion-pion scattering phases, the pion electromagnetic form factor, the mean squared radius of a K-meson, and the electric and magnetic polarizabilities of pions are calculated using the superpropagator method. The rho-meson mass, Msub(rho)=800 MeV, is calculated too
Strongly interacting bosons in a one-dimensional optical lattice at incommensurate densities
Lazarides, A.|info:eu-repo/dai/nl/315556668; Tieleman, O.|info:eu-repo/dai/nl/341386456; de Morais Smith, C.|info:eu-repo/dai/nl/304836346
2011-01-01
We investigate quantum phase transitions occurring in a system of strongly interacting ultracold bosons in a one-dimensional optical lattice. After discussing the commensurate-incommensurate transition, we focus on the phases appearing at an incommensurate filling. We find a rich phase diagram, with
DEFF Research Database (Denmark)
Petrosyan, David; Molmer, Klaus
2013-01-01
We study two-photon excitation of Rydberg states of atoms under stimulated adiabatic passage with delayed laser pulses. We find that the combination of strong interaction between the atoms in Rydberg state and the spontaneous decay of the intermediate exited atomic state leads to the Rydberg...
The strong interaction in e+e- annihilation and deep inelastic scattering
International Nuclear Information System (INIS)
Samuelsson, J.
1996-01-01
Various aspects of strong interactions are considered. Correlation effects in the hadronization process in a string model are studied. A discrete approximation scheme to the perturbative QCD cascade in e + e - annihilation is formulated. The model, Discrete QCD, predicts a rather low phase space density of 'effective gluons'. This is related to the properties of the running coupling constant. It provides us with a simple tool for studies of the strong interaction. It is shown that it reproduces well-known properties of parton cascades. A new formalism for the Deep Inelastic Scattering (DIS) process is developed. The model which is called the Linked Dipole Chain Model provides an interpolation between regions of high Q 2 (DGLAP) and low x-moderate Q 2 (BFKL). It gives a unified treatment of the different interaction channels an a DIS process. 17 figs
Strongly interacting dark matter: Self-interactions and keV lines
Boddy, Kimberly K.; Feng, Jonathan L.; Kaplinghat, Manoj; Shadmi, Yael; Tait, Timothy M. P.
2014-11-01
We consider a simple supersymmetric hidden sector: pure SU (N ) gauge theory. Dark matter is made up of hidden glueballinos with mass mX and hidden glueballs with mass near the confinement scale Λ . For mX˜1 TeV and Λ ˜100 MeV , the glueballinos freeze out with the correct relic density and self-interact through glueball exchange to resolve small-scale structure puzzles. An immediate consequence is that the glueballino spectrum has a hyperfine splitting of order Λ2/mX˜10 keV . We show that the radiative decays of the excited state can explain the observed 3.5 keV x-ray line signal from clusters of galaxies, Andromeda, and the Milky Way.
Quantum phases of dipolar rotors on two-dimensional lattices.
Abolins, B P; Zillich, R E; Whaley, K B
2018-03-14
The quantum phase transitions of dipoles confined to the vertices of two-dimensional lattices of square and triangular geometry is studied using path integral ground state quantum Monte Carlo. We analyze the phase diagram as a function of the strength of both the dipolar interaction and a transverse electric field. The study reveals the existence of a class of orientational phases of quantum dipolar rotors whose properties are determined by the ratios between the strength of the anisotropic dipole-dipole interaction, the strength of the applied transverse field, and the rotational constant. For the triangular lattice, the generic orientationally disordered phase found at zero and weak values of both dipolar interaction strength and applied field is found to show a transition to a phase characterized by net polarization in the lattice plane as the strength of the dipole-dipole interaction is increased, independent of the strength of the applied transverse field, in addition to the expected transition to a transverse polarized phase as the electric field strength increases. The square lattice is also found to exhibit a transition from a disordered phase to an ordered phase as the dipole-dipole interaction strength is increased, as well as the expected transition to a transverse polarized phase as the electric field strength increases. In contrast to the situation with a triangular lattice, on square lattices, the ordered phase at high dipole-dipole interaction strength possesses a striped ordering. The properties of these quantum dipolar rotor phases are dominated by the anisotropy of the interaction and provide useful models for developing quantum phases beyond the well-known paradigms of spin Hamiltonian models, implementing in particular a novel physical realization of a quantum rotor-like Hamiltonian that possesses an anisotropic long range interaction.
Quantum phases of dipolar rotors on two-dimensional lattices
Abolins, B. P.; Zillich, R. E.; Whaley, K. B.
2018-03-01
The quantum phase transitions of dipoles confined to the vertices of two-dimensional lattices of square and triangular geometry is studied using path integral ground state quantum Monte Carlo. We analyze the phase diagram as a function of the strength of both the dipolar interaction and a transverse electric field. The study reveals the existence of a class of orientational phases of quantum dipolar rotors whose properties are determined by the ratios between the strength of the anisotropic dipole-dipole interaction, the strength of the applied transverse field, and the rotational constant. For the triangular lattice, the generic orientationally disordered phase found at zero and weak values of both dipolar interaction strength and applied field is found to show a transition to a phase characterized by net polarization in the lattice plane as the strength of the dipole-dipole interaction is increased, independent of the strength of the applied transverse field, in addition to the expected transition to a transverse polarized phase as the electric field strength increases. The square lattice is also found to exhibit a transition from a disordered phase to an ordered phase as the dipole-dipole interaction strength is increased, as well as the expected transition to a transverse polarized phase as the electric field strength increases. In contrast to the situation with a triangular lattice, on square lattices, the ordered phase at high dipole-dipole interaction strength possesses a striped ordering. The properties of these quantum dipolar rotor phases are dominated by the anisotropy of the interaction and provide useful models for developing quantum phases beyond the well-known paradigms of spin Hamiltonian models, implementing in particular a novel physical realization of a quantum rotor-like Hamiltonian that possesses an anisotropic long range interaction.
Heavy quark mass effects and improved tests of the flavor independence of strong interactions
Energy Technology Data Exchange (ETDEWEB)
Burrows, P.N. [Univ. of Oxford (United Kingdom); SLD Collaboration
1998-08-01
A review is given of latest results on tests of the flavor independence of strong interactions. Heavy quark mass effects are evident in the data and are now taken into account at next-to-leading order in QCD perturbation theory. The strong-coupling ratios {alpha}{sub s}{sup b}/{alpha}{sub s}{sup uds} and {alpha}{sub s}{sup c}/{alpha}{sub s}{sup uds} are found to be consistent with unity. Determinations of the b-quark mass m{sub b} (M{sub Z}) are discussed.
Strong field approximation within a Faddeev-like formalism for laser-matter interactions
International Nuclear Information System (INIS)
Popov, Y.; Galstyan, A.; Piraux, B.; Mota-Furtado, F.; O'Mahony, P.F.
2017-01-01
We consider the interaction of atomic hydrogen with an intense laser field within the strong-field approximation (SFA). By using a Faddeev-like formalism, we introduce a new perturbative series in the binding potential of the atom. As a first test of this new approach, we calculate the electron energy spectrum in the very simple case of a photon energy higher than the ionisation potential. We show that by contrast to the standard perturbative series in the binding potential obtained within the strong field approximation, the first terms of the new series converge rapidly towards the results we get by solving the corresponding time-dependent Schroedinger equation. (authors)
Yokoyama, Tomohiro; Eto, Mikio; Nazarov, Yuli
2014-03-01
We theoretically investigate the Josephson junction using quasi-one dimensional semiconductor nanowires with strong spin-orbit (SO) interaction, e.g., InSb. First, we examine a simple model using a single scatterer to describe the elastic scattering due to impurities and SO interaction in the normal region.[1] The Zeeman effect is taken into account by the spin-dependent phase shift of electron and hole through the system. The interplay between SO interaction and Zeeman effect results in a finite supercurrent even when the phase difference between two superconductors is zero. Moreover, the critical current depends on its current direction if more than one conduction channel is present in the nanowire. Next, we perform a numerical simulation by the tight-binding model for the nanowire to confirm our simple model. Then, we show that a spin-dependent Fermi velocity due to the SO interaction causes the anomalous Josephson effect.
International Nuclear Information System (INIS)
Sivan, N.; Levit, S.
1992-01-01
We present a semiclassical theory of charged interacting anyons in a strong magnetic field. We derive the appropriate generalization of the WKB quantization conditions and determine the corresponding wave functions for non separable integrable anyonic systems. This theory is applies to a system of two interacting anyons, two interacting anyons in the presence of an impurity and three interacting anyons. We calculate the dependence of the semiclassical energy levels on the statistical parameter and find regions in which dependence follows very different patterns. The semiclassical treatment allows to find the correlation between these patterns and the change in the character of the classical motion of the system. We also test the accuracy of the mean field approximation for low and high energy states of the three anyons. (author)
DEFF Research Database (Denmark)
Vinther, Joachim Møllesøe; Nielsen, Anders B.; Bjerring, Morten
2012-01-01
A novel strategy for heteronuclear dipolar decoupling in magic-angle spinning solid-state NMR spectroscopy is presented, which eliminates residual static high-order terms in the effective Hamiltonian originating from interactions between oscillating dipolar and anisotropic shielding tensors. The ...
International Nuclear Information System (INIS)
Arnold, R.C.
1975-12-01
A systematic calculus of long-range Regge cut effects in multiparticle production is constructed in the form of an infrared-divergent stochastic field theory. Total cross sections and two-body overlap integrals in such a theory may depend very sensitively upon internal quantum-numbers of incident particles, resulting in a strong symmetry breaking at ultra-high energies. Such symmetry violations will influence low energy processes through dispersion relations, and a bootstrap of weak interactions becomes possible. A rough analytic estimate of the scale of thresholds for such effects yields a BCS-type gap equation, which expresses the scale of weak and electromagnetic couplings in terms of purely strong-interaction parameters
Bogolubov–Hartree–Fock Theory for Strongly Interacting Fermions in the Low Density Limit
Energy Technology Data Exchange (ETDEWEB)
Bräunlich, Gerhard [Friedrich-Schiller-University Jena, Institute for Mathematics (Germany); Hainzl, Christian [University of Tübingen, Mathematical Institute (Germany); Seiringer, Robert, E-mail: robert.seiringer@ist.ac.at [Institute of Science and Technology Austria (Austria)
2016-06-15
We consider the Bogolubov–Hartree–Fock functional for a fermionic many-body system with two-body interactions. For suitable interaction potentials that have a strong enough attractive tail in order to allow for two-body bound states, but are otherwise sufficiently repulsive to guarantee stability of the system, we show that in the low-density limit the ground state of this model consists of a Bose–Einstein condensate of fermion pairs. The latter can be described by means of the Gross–Pitaevskii energy functional.
Strong constraints on self-interacting dark matter with light mediators
International Nuclear Information System (INIS)
Bringmann, Torsten; Walia, Parampreet
2017-04-01
Coupling dark matter to light new particles is an attractive way to combine thermal production with strong velocity-dependent self-interactions. Here we point out that in such models the dark matter annihilation rate is generically enhanced by the Sommerfeld effect, and we derive the resulting constraints from the Cosmic Microwave Background and other indirect detection probes. For the frequently studied case of s-wave annihilation these constraints exclude the entire parameter space where the self-interactions are large enough to address the small-scale problems of structure formation.
Strong enhancement of light-matter interaction in graphene coupled to a photonic crystal nanocavity.
Gan, Xuetao; Mak, Kin Fai; Gao, Yuanda; You, Yumeng; Hatami, Fariba; Hone, James; Heinz, Tony F; Englund, Dirk
2012-11-14
We demonstrate a large enhancement in the interaction of light with graphene through coupling with localized modes in a photonic crystal nanocavity. Spectroscopic studies show that a single atomic layer of graphene reduces the cavity reflection by more than a factor of one hundred, while also sharply reducing the cavity quality factor. The strong interaction allows for cavity-enhanced Raman spectroscopy on subwavelength regions of a graphene sample. A coupled-mode theory model matches experimental observations and indicates significantly increased light absorption in the graphene layer. The coupled graphene-cavity system also enables precise measurements of graphene's complex refractive index.
Equilibration Dynamics of Strongly Interacting Bosons in 2D Lattices with Disorder.
Yan, Mi; Hui, Hoi-Yin; Rigol, Marcos; Scarola, V W
2017-08-18
Motivated by recent optical lattice experiments [J.-y. Choi et al., Science 352, 1547 (2016)SCIEAS0036-807510.1126/science.aaf8834], we study the dynamics of strongly interacting bosons in the presence of disorder in two dimensions. We show that Gutzwiller mean-field theory (GMFT) captures the main experimental observations, which are a result of the competition between disorder and interactions. Our findings highlight the difficulty in distinguishing glassy dynamics, which can be captured by GMFT, and many-body localization, which cannot be captured by GMFT, and indicate the need for further experimental studies of this system.
Gauge unification of basic forces, particularly of gravitation with strong interactions
International Nuclear Information System (INIS)
Salam, A.
1977-01-01
An attempt is made to present a case for the use of both the Einstein--Weyl spin-two and the Yang--Mills spin-one gauge structures for describing strong interactions. By emphasizing both spin-one and -two aspects of this force, it is hoped that a unification of this force, on the one hand, with gravity theory and, on the other, with the electromagnetic and weak interactions can be achieved. A Puppi type of tetrahedral interralation of fundamental forces, with the strong force playing a pivotal role due to its mediation through both spin-one and -two quanta, is proposed. It is claimed that the gauge invariance of gravity theory permits the use of ambuguity-free nonpolynomial techniques and thereby the securing of relistic regularization in gravity-modified field theories with the Newtonian constant G/sub N/ providing a relistic cutoff. 37 references
Les Houches Summer School : Strongly Interacting Quantum Systems out of Equilibrium
Millis, Andrew J; Parcollet, Olivier; Saleur, Hubert; Cugliandolo, Leticia F
2016-01-01
Over the last decade new experimental tools and theoretical concepts are providing new insights into collective nonequilibrium behavior of quantum systems. The exquisite control provided by laser trapping and cooling techniques allows us to observe the behavior of condensed bose and degenerate Fermi gases under nonequilibrium drive or after quenches' in which a Hamiltonian parameter is suddenly or slowly changed. On the solid state front, high intensity short-time pulses and fast (femtosecond) probes allow solids to be put into highly excited states and probed before relaxation and dissipation occur. Experimental developments are matched by progress in theoretical techniques ranging from exact solutions of strongly interacting nonequilibrium models to new approaches to nonequilibrium numerics. The summer school Strongly interacting quantum systems out of equilibrium' held at the Les Houches School of Physics as its XCIX session was designed to summarize this progress, lay out the open questions and define dir...
On the Frequency Distribution of Neutral Particles from Low-Energy Strong Interactions
Directory of Open Access Journals (Sweden)
Federico Colecchia
2017-01-01
Full Text Available The rejection of the contamination, or background, from low-energy strong interactions at hadron collider experiments is a topic that has received significant attention in the field of particle physics. This article builds on a particle-level view of collision events, in line with recently proposed subtraction methods. While conventional techniques in the field usually concentrate on probability distributions, our study is, to our knowledge, the first attempt at estimating the frequency distribution of background particles across the kinematic space inside individual collision events. In fact, while the probability distribution can generally be estimated given a model of low-energy strong interactions, the corresponding frequency distribution inside a single event typically deviates from the average and cannot be predicted a priori. We present preliminary results in this direction and establish a connection between our technique and the particle weighting methods that have been the subject of recent investigation at the Large Hadron Collider.
Thermodynamics of strongly interacting fermions in two-dimensional optical lattices
Energy Technology Data Exchange (ETDEWEB)
Khatami, Ehsan; Rigol, Marcos [Department of Physics, Georgetown University, Washington DC, 20057 (United States); Kavli Institute for Theoretical Physics, University of California, Santa Barbara, Santa Barbara, California 93106 (United States)
2011-11-15
We study finite-temperature properties of strongly correlated fermions in two-dimensional optical lattices by means of numerical linked cluster expansions, a computational technique that allows one to obtain exact results in the thermodynamic limit. We focus our analysis on the strongly interacting regime, where the on-site repulsion is of the order of or greater than the band width. We compute the equation of state, double occupancy, entropy, uniform susceptibility, and spin correlations for temperatures that are similar to or below the ones achieved in current optical lattice experiments. We provide a quantitative analysis of adiabatic cooling of trapped fermions in two dimensions, by means of both flattening the trapping potential and increasing the interaction strength.
Limitations due to strong head-on beam-beam interactions (MD 1434)
Buffat, Xavier; Iadarola, Giovanni; Papadopoulou, Parthena Stefania; Papaphilippou, Yannis; Pellegrini, Dario; Pojer, Mirko; Crockford, Guy; Salvachua Ferrando, Belen Maria; Trad, Georges; Barranco Garcia, Javier; Pieloni, Tatiana; Tambasco, Claudia; CERN. Geneva. ATS Department
2017-01-01
The results of an experiment aiming at probing the limitations due to strong head on beam-beam interactions are reported. It is shown that the loss rates significantly increase when moving the working point up and down the diagonal, possibly due to effects of the 10th and/or 14th order resonances. Those limitations are tighter for bunches with larger beam-beam parameters, a maximum total beam-beam tune shift just below 0.02 could be reached.
Model for Thermal Relic Dark Matter of Strongly Interacting Massive Particles.
Hochberg, Yonit; Kuflik, Eric; Murayama, Hitoshi; Volansky, Tomer; Wacker, Jay G
2015-07-10
A recent proposal is that dark matter could be a thermal relic of 3→2 scatterings in a strongly coupled hidden sector. We present explicit classes of strongly coupled gauge theories that admit this behavior. These are QCD-like theories of dynamical chiral symmetry breaking, where the pions play the role of dark matter. The number-changing 3→2 process, which sets the dark matter relic abundance, arises from the Wess-Zumino-Witten term. The theories give an explicit relationship between the 3→2 annihilation rate and the 2→2 self-scattering rate, which alters predictions for structure formation. This is a simple calculable realization of the strongly interacting massive-particle mechanism.
arXiv Recent results and future of the NA61/SHINE strong interactions program
Lysakowski, Bartosz
2018-01-01
NA61/SHINE is a fixed target experiment at the CERN Super-Proton- Synchrotron. The main goals of the experiment are to discover the critical point of strongly interacting matter and study the properties of the onset of deconfnement. In order to reach these goals the collaboration studies hadron production properties in nucleus-nucleus, proton-proton and proton-nucleus interactions. In this talk, recent results on particle production in p+p interactions, as well as Be+Be and Ar+Sc collisions in the SPS energy range are reviewed. The results are compared with available world data. The future of the NA61/SHINE scientifc program is also presented.
Strong late-time circumstellar interaction in the peculiar supernova iPTF14hls
Andrews, Jennifer E.; Smith, Nathan
2018-03-01
We present a moderate-resolution spectrum of the peculiar Type II supernova iPTF14hls taken on day 1153 after discovery. This spectrum reveals the clear signature of shock interaction with dense circumstellar material (CSM). We suggest that this CSM interaction may be an important clue for understanding the extremely unusual photometric and spectroscopic evolution seen over the first 600 days of iPTF14hls. The late-time spectrum shows a double-peaked intermediate-width Hα line indicative of expansion speeds around 1000 km s-1, with the double-peaked shape hinting at a disc-like geometry in the CSM. If the CSM was highly asymmetric, perhaps in a disc or torus that was ejected from the star 3-6 years prior to explosion, then the CSM interaction could have been overrun and hidden below the SN ejecta photosphere from a wide range of viewing angles. In that case, CSM interaction luminosity would have been thermalized well below the photosphere, potentially sustaining the high luminosity without exhibiting the traditional observational signatures of strong CSM interaction (narrow Hα emission and X-rays). Variations in density structure of the CSM could account for the multiple rebrightenings of the lightcurve. We propose that a canonical 1× 1051 erg explosion energy with enveloped CSM interaction as seen in some recent SNe, rather than an entirely new explosion mechanism, may be adequate to explain the peculiar evolution of iPTF14hls.
Role of high-order dispersion on strong-field laser-molecule interactions
Dantus, Marcos; Nairat, Muath
2016-05-01
Strong-field (1012- 1016 W/ cm2) laser-matter interactions are characterized by the extent of fragmentation and charge of the resulting ions as a function of peak intensity and pulse duration. Interactions are influenced by high-order dispersion, which is difficult to characterize and compress. Fourth-order dispersion (FOD) causes a time-symmetric pedestal, while third-order dispersion (TOD) causes a leading (negative) or following (positive) pedestal. Here, we report on strong-field interactions with pentane and toluene molecules, tracking the molecular ion and the doubly charged carbon ion C2+ yields as a function of TOD and FOD for otherwise transform-limited (TL) 35fs pulses. We find TL pulses enhance molecular ion yield and suppress C2+ yield, while FOD reverses this trend. Interestingly, the leading pedestal in negative TOD enhances C2+ yield compared to positive TOD. Pulse pedestals are of particular importance in strong-field science because target ionization or alignment can be induced well before the main pulse arrives. A pedestal following an intense laser pulse can cause sequential ionization or accelerate electrons causing cascaded ionization. Control of high-order dispersion allows us to provide strong-field measurements that can help address the mechanisms responsible for different product ions in the presence and absence of pedestals. Financial support of this work comes from the Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy, DOE SISGR (DE-SC0002325)
Dipolar vortices in two-dimensional flows
DEFF Research Database (Denmark)
Juul Rasmussen, J.; Hesthaven, J.S.; Lynov, Jens-Peter
1996-01-01
The dynamics of dipolar vortex solutions to the two-dimensional Euler equations is studied. A new type of nonlinear dipole is found and its dynamics in a slightly viscous system is compared with the dynamics of the Lamb dipole. The evolution of dipolar structures from an initial turbulent patch...
Directory of Open Access Journals (Sweden)
Aditi Gupta
2016-03-01
Full Text Available Epistatic interactions between residues determine a protein's adaptability and shape its evolutionary trajectory. When a protein experiences a changed environment, it is under strong selection to find a peak in the new fitness landscape. It has been shown that strong selection increases epistatic interactions as well as the ruggedness of the fitness landscape, but little is known about how the epistatic interactions change under selection in the long-term evolution of a protein. Here we analyze the evolution of epistasis in the protease of the human immunodeficiency virus type 1 (HIV-1 using protease sequences collected for almost a decade from both treated and untreated patients, to understand how epistasis changes and how those changes impact the long-term evolvability of a protein. We use an information-theoretic proxy for epistasis that quantifies the co-variation between sites, and show that positive information is a necessary (but not sufficient condition that detects epistasis in most cases. We analyze the "fossils" of the evolutionary trajectories of the protein contained in the sequence data, and show that epistasis continues to enrich under strong selection, but not for proteins whose environment is unchanged. The increase in epistasis compensates for the information loss due to sequence variability brought about by treatment, and facilitates adaptation in the increasingly rugged fitness landscape of treatment. While epistasis is thought to enhance evolvability via valley-crossing early-on in adaptation, it can hinder adaptation later when the landscape has turned rugged. However, we find no evidence that the HIV-1 protease has reached its potential for evolution after 9 years of adapting to a drug environment that itself is constantly changing. We suggest that the mechanism of encoding new information into pairwise interactions is central to protein evolution not just in HIV-1 protease, but for any protein adapting to a changing
Directory of Open Access Journals (Sweden)
D.-Y. Lee
2000-12-01
Full Text Available Some observational features on the July 5, 1995 substorm event are presented using the data from the Geotail satellite which was located at near-Earth plasma sheet, XGSE ¡ -9.6 R_E, and quite close to the onset sector. Near-tail magnetic field reveals the typical dipolarizations starting at ¡ 1104 UT until ¡ 1113 UT. During the interval, two dipolarizations occur: First dipolarization is not strong and accompanies only weak ( 450 km/s was observed, but delayed by ¡ 1 min with respect to the second dipolarization initiation. These features are in conflict with the flow-braking scenario for the substorm. Rather they fit better in the near-tail current disruption scenario.
Ghodrat, Malihe; Naji, Ali; Komaie-Moghaddam, Haniyeh; Podgornik, Rudolf
2015-05-07
We study the effective interaction mediated by strongly coupled Coulomb fluids between dielectric surfaces carrying quenched, random monopolar charges with equal mean and variance, both when the Coulomb fluid consists only of mobile multivalent counterions and when it consists of an asymmetric ionic mixture containing multivalent and monovalent (salt) ions in equilibrium with an aqueous bulk reservoir. We analyze the consequences that follow from the interplay between surface charge disorder, dielectric and salt image effects, and the strong electrostatic coupling that results from multivalent counterions on the distribution of these ions and the effective interaction pressure they mediate between the surfaces. In a dielectrically homogeneous system, we show that the multivalent counterions are attracted towards the surfaces with a singular, disorder-induced potential that diverges logarithmically on approach to the surfaces, creating a singular but integrable counterion density profile that exhibits an algebraic divergence at the surfaces with an exponent that depends on the surface charge (disorder) variance. This effect drives the system towards a state of lower thermal 'disorder', one that can be described by a renormalized temperature, exhibiting thus a remarkable antifragility. In the presence of an interfacial dielectric discontinuity, the singular behavior of counterion density at the surfaces is removed but multivalent counterions are still accumulated much more strongly close to randomly charged surfaces as compared with uniformly charged ones. The interaction pressure acting on the surfaces displays in general a highly non-monotonic behavior as a function of the inter-surface separation with a prominent regime of attraction at small to intermediate separations. This attraction is caused directly by the combined effects from charge disorder and strong coupling electrostatics of multivalent counterions, which dominate the surface-surface repulsion due to
Independent EEG sources are dipolar.
Directory of Open Access Journals (Sweden)
Arnaud Delorme
Full Text Available Independent component analysis (ICA and blind source separation (BSS methods are increasingly used to separate individual brain and non-brain source signals mixed by volume conduction in electroencephalographic (EEG and other electrophysiological recordings. We compared results of decomposing thirteen 71-channel human scalp EEG datasets by 22 ICA and BSS algorithms, assessing the pairwise mutual information (PMI in scalp channel pairs, the remaining PMI in component pairs, the overall mutual information reduction (MIR effected by each decomposition, and decomposition 'dipolarity' defined as the number of component scalp maps matching the projection of a single equivalent dipole with less than a given residual variance. The least well-performing algorithm was principal component analysis (PCA; best performing were AMICA and other likelihood/mutual information based ICA methods. Though these and other commonly-used decomposition methods returned many similar components, across 18 ICA/BSS algorithms mean dipolarity varied linearly with both MIR and with PMI remaining between the resulting component time courses, a result compatible with an interpretation of many maximally independent EEG components as being volume-conducted projections of partially-synchronous local cortical field activity within single compact cortical domains. To encourage further method comparisons, the data and software used to prepare the results have been made available (http://sccn.ucsd.edu/wiki/BSSComparison.
Dipolar droplets in bosonic erbium quantum fluids
Chomaz, Lauriane; Baier, Simon; Petter, Daniel; Faraoni, Giulia; Becher, Jan-Hendrik; van Bijnen, Rick; Mark, Manfred J.; Ferlaino, Francesca
2017-04-01
Due to their large magnetic moment and exotic electronic configuration, atoms of the lanthanide family, such as dysprosium (Dy) and erbium (Er), are an ideal platform for exploring the competition between inter-particle interactions of different origins and behaviors. Recently, a novel phase of dilute droplet has been observed in an ultracold gas of bosonic Dy when changing the ratio of the contact and dipole-dipole interactions and setting the mean-field interactions to slightly attractive. This has been attributed to the distinct, non-vanishing, beyond-mean-field effects in dipolar gases when the mean interaction cancels. Here we report on the investigation of droplet physics in fluids of bosonic Er. By precise control of the scattering length a, we quantitatively probe the Bose-Einstein condensate (BEC)-to-droplet phase diagram and the rich underlying dynamics. In a prolate geometry, we observe a crossover from a BEC to a single macro-droplet, prove the stabilizing role of quantum fluctuations and characterize the special dynamical properties of the droplet. In an oblate geometry, we observe the formation of assemblies of tinier droplets arranged in a chain and explore the special state dynamics following a quench of a, marked by successive merging and reformation events. L.C. is supported within the Marie Curie Individual Fellowship DIPPHASE No. 706809 of the European Commission.
Observation of Spin-Polarons in a strongly interacting Fermi liquid
Zwierlein, Martin
2009-03-01
We have observed spin-polarons in a highly imbalanced mixture of fermionic atoms using tomographic RF spectroscopy. Feshbach resonances allow to freely tune the interactions between the two spin states involved. A single spin down atom immersed in a Fermi sea of spin up atoms can do one of two things: For strong attraction, it can form a molecule with exactly one spin up partner, but for weaker interaction it will spread its attraction and surround itself with a collection of majority atoms. This spin down atom ``dressed'' with a spin up cloud constitutes the spin-polaron. We have observed a striking spectroscopic signature of this quasi-particle for various interaction strengths, a narrow peak in the spin down spectrum that emerges above a broad background. The narrow width signals a long lifetime of the spin-polaron, much longer than the collision rate with spin up atoms, as it must be for a proper quasi-particle. The peak position allows to directly measure the polaron energy. The broad pedestal at high energies reveals physics at short distances and is thus ``molecule-like'': It is exactly matched by the spin up spectra. The comparison with the area under the polaron peak allows to directly obtain the quasi-particle weight Z. We observe a smooth transition from polarons to molecules. At a critical interaction strength of 1/kFa = 0.7, the polaron peak vanishes and spin up and spin down spectra exactly match, signalling the formation of molecules. This is the same critical interaction strength found earlier to separate a normal Fermi mixture from a superfluid molecular Bose-Einstein condensate. The spin-polarons determine the low-temperature phase diagram of imbalanced Fermi mixtures. In principle, polarons can interact with each other and should, at low enough temperatures, form a superfluid of p-wave pairs. We will present a first indication for interactions between polarons.
Quantum criticality of one-dimensional multicomponent Fermi gas with strongly attractive interaction
International Nuclear Information System (INIS)
He, Peng; Jiang, Yuzhu; Guan, Xiwen; He, Jinyu
2015-01-01
Quantum criticality of strongly attractive Fermi gas with SU(3) symmetry in one dimension is studied via the thermodynamic Bethe ansatz (TBA) equations. The phase transitions driven by the chemical potential μ, effective magnetic field H 1 , H 2 (chemical potential biases) are analyzed at the quantum criticality. The phase diagram and critical fields are analytically determined by the TBA equations in the zero temperature limit. High accurate equations of state, scaling functions are also obtained analytically for the strong interacting gases. The dynamic exponent z=2 and correlation length exponent ν=1/2 read off the universal scaling form. It turns out that the quantum criticality of the three-component gases involves a sudden change of density of states of one cluster state, two or three cluster states. In general, this method can be adapted to deal with the quantum criticality of multicomponent Fermi gases with SU(N) symmetry. (paper)
Adsorbate-mediated strong metal-support interactions in oxide-supported Rh catalysts.
Matsubu, John C; Zhang, Shuyi; DeRita, Leo; Marinkovic, Nebojsa S; Chen, Jingguang G; Graham, George W; Pan, Xiaoqing; Christopher, Phillip
2017-02-01
The optimization of supported metal catalysts predominantly focuses on engineering the metal site, for which physical insights based on extensive theoretical and experimental contributions have enabled the rational design of active sites. Although it is well known that supports can influence the catalytic properties of metals, insights into how metal-support interactions can be exploited to optimize metal active-site properties are lacking. Here we utilize in situ spectroscopy and microscopy to identify and characterize a support effect in oxide-supported heterogeneous Rh catalysts. This effect is characterized by strongly bound adsorbates (HCO x ) on reducible oxide supports (TiO 2 and Nb 2 O 5 ) that induce oxygen-vacancy formation in the support and cause HCO x -functionalized encapsulation of Rh nanoparticles by the support. The encapsulation layer is permeable to reactants, stable under the reaction conditions and strongly influences the catalytic properties of Rh, which enables rational and dynamic tuning of CO 2 -reduction selectivity.
Studies of the strong and electroweak interactions at the Z0 pole
International Nuclear Information System (INIS)
Hildreth, M.D.
1995-03-01
This thesis presents studies of the strong and electroweak forces, two of the fundamental interactions that govern the behavior of matter at high energies. The authors have used the hadronic decays of Z 0 bosons produced with the unique experimental apparatus of the e + e - Linear Collider at the Stanford Linear Accelerator Center (SLAC) and the SLAC Large Detector (SLD) for these measurements. Employing the precision tracking capabilities of the SLD, they isolated samples of Z 0 events containing primarily the decays of the Z 0 to a chosen quark type. With an inclusive selection technique, they have tested the flavor independence of the strong coupling, α s by measuring the rates of multi-jet production in isolated samples of light (uds), c, and b quark events. They find: α s uds /α s all 0.987 ± 0.027(stat) ± 0.022(syst) ± 0.022(theory), α s c /α s all = 1.012 ± 0.104(stat) ± 0.102(syst) ± 0.096(theory), α s b /α s all = 1.026 ± 0.041(stat) ± 0.030(theory), which implies that the strong interaction is independent of quark flavor within the present experimental sensitivity. They have also measured the extent of parity-violation in the Z 0 c bar c coupling, given by the parameter A c 0 , using a sample of fully and partially reconstructed D* and D + meson decays and the longitudinal polarization of the SLC electron beam. This sample of charm quark events was derived with selection techniques based on their kinematic properties and decay topologies. They find A c 0 = 0.73 ± 0.22(stat) ± 0.10(syst). This value is consistent with that expected in the electroweak standard model of particle interactions
Dipolar dark matter as an effective field theory
Blanchet, Luc; Heisenberg, Lavinia
2017-10-01
Dipolar dark matter is an alternative model motivated by the challenges faced by the standard cold dark matter model to describe the right phenomenology at galactic scales. A promising realization of dipolar dark matter was recently proposed in the context of massive bigravity theory. The model contains dark matter particles as well as a vector field coupled to the effective composite metric of bigravity. This model is completely safe in the gravitational sector thanks to the underlying properties of massive bigravity. In this work, we investigate the exact decoupling limit of the theory, including the contribution of the matter sector, and prove that it is free of ghosts in this limit. We conclude that the theory is acceptable as an effective field theory below the strong coupling scale.
Evidence for strong Breit interaction in dielectronic recombination of highly charged heavy ions.
Nakamura, Nobuyuki; Kavanagh, Anthony P; Watanabe, Hirofumi; Sakaue, Hiroyuki A; Li, Yueming; Kato, Daiji; Currell, Fred J; Ohtani, Shunsuke
2008-02-22
Resonant strengths have been measured for dielectronic recombination of Li-like iodine, holmium, and bismuth using an electron beam ion trap. By observing the atomic number dependence of the state-resolved resonant strength, clear experimental evidence has been obtained that the importance of the generalized Breit interaction (GBI) effect on dielectronic recombination increases as the atomic number increases. In particular, it has been shown that the GBI effect is exceptionally strong for the recombination through the resonant state [1s2s(2)2p(1/2)](1).
Viscosity in strongly interacting quantum field theories from black hole physics.
Kovtun, P K; Son, D T; Starinets, A O
2005-03-25
The ratio of shear viscosity to volume density of entropy can be used to characterize how close a given fluid is to being perfect. Using string theory methods, we show that this ratio is equal to a universal value of variant Planck's over 2pi/4pik(B) for a large class of strongly interacting quantum field theories whose dual description involves black holes in anti-de Sitter space. We provide evidence that this value may serve as a lower bound for a wide class of systems, thus suggesting that black hole horizons are dual to the most ideal fluids.
Mechanism for thermal relic dark matter of strongly interacting massive particles.
Hochberg, Yonit; Kuflik, Eric; Volansky, Tomer; Wacker, Jay G
2014-10-24
We present a new paradigm for achieving thermal relic dark matter. The mechanism arises when a nearly secluded dark sector is thermalized with the standard model after reheating. The freeze-out process is a number-changing 3→2 annihilation of strongly interacting massive particles (SIMPs) in the dark sector, and points to sub-GeV dark matter. The couplings to the visible sector, necessary for maintaining thermal equilibrium with the standard model, imply measurable signals that will allow coverage of a significant part of the parameter space with future indirect- and direct-detection experiments and via direct production of dark matter at colliders. Moreover, 3→2 annihilations typically predict sizable 2→2 self-interactions which naturally address the "core versus cusp" and "too-big-to-fail" small-scale structure formation problems.
Many-body Anderson localization of strongly interacting bosons in random lattices
International Nuclear Information System (INIS)
Katzer, Roman
2015-05-01
In the present work, we investigate the problem of many-body localization of strongly interacting bosons in random lattices within the disordered Bose-Hubbard model. This involves treating both the local Mott-Hubbard physics as well as the non-local quantum interference processes, which give rise to the phenomenon of Anderson localization, within the same theory. In order to determine the interaction induced transition to the Mott insulator phase, it is necessary to treat the local particle interaction exactly. Therefore, here we use a mean-field approach that approximates only the kinetic term of the Hamiltonian. This way, the full problem of interacting bosons on a random lattice is reduced to a local problem of a single site coupled to a particle bath, which has to be solved self-consistently. In accordance to previous works, we find that a finite disorder width leads to a reduced size of the Mott insulating regions. The transition from the superfluid phase to the Bose glass phase is driven by the non-local effect of Anderson localization. In order to describe this transition, one needs to work within a theory that is non-local as well. Therefore, here we introduce a new approach to the problem. Based on the results for the local excitation spectrum obtained within the mean-field theory, we reduce the full, interacting model to an effective, non-interacting model by applying a truncation scheme to the Hilbert space. Evaluating the long-ranged current density within this approximation, we identify the transition from the Bose glass to the superfluid phase with the Anderson transition of the effective model. Resolving this transition using the self-consistent theory of localization, we obtain the full phase diagram of the disordered Bose-Hubbard model in the regime of strong interaction and larger disorder. In accordance to the theorem of inclusions, we find that the Mott insulator and the superfluid phase are always separated by the compressible, but insulating
Bose-Einstein condensation and superfluidity of dipolar excitons in a phosphorene double layer
Berman, Oleg L.; Gumbs, Godfrey; Kezerashvili, Roman Ya.
2017-07-01
We study the formation of dipolar excitons and their superfluidity in a phosphorene double layer. The analytical expressions for the single dipolar exciton energy spectrum and wave function are obtained. It is predicted that a weakly interacting gas of dipolar excitons in a double layer of black phosphorus exhibits superfluidity due to the dipole-dipole repulsion between the dipolar excitons. In calculations are employed the Keldysh and Coulomb potentials for the interaction between the charge carriers to analyze the influence of the screening effects on the studied phenomena. It is shown that the critical velocity of superfluidity, the spectrum of collective excitations, concentrations of the superfluid and normal component, and mean-field critical temperature for superfluidity are anisotropic and demonstrate the dependence on the direction of motion of dipolar excitons. The critical temperature for superfluidity increases if the exciton concentration and the interlayer separation increase. It is shown that the dipolar exciton binding energy and mean-field critical temperature for superfluidity are sensitive to the electron and hole effective masses. The proposed experiment to observe a directional superfluidity of excitons is addressed.
Davis, J. C. Séamus; Lee, Dung-Hai
2013-01-01
Unconventional superconductivity (SC) is said to occur when Cooper pair formation is dominated by repulsive electron–electron interactions, so that the symmetry of the pair wave function is other than an isotropic s-wave. The strong, on-site, repulsive electron–electron interactions that are the proximate cause of such SC are more typically drivers of commensurate magnetism. Indeed, it is the suppression of commensurate antiferromagnetism (AF) that usually allows this type of unconventional superconductivity to emerge. Importantly, however, intervening between these AF and SC phases, intertwined electronic ordered phases (IP) of an unexpected nature are frequently discovered. For this reason, it has been extremely difficult to distinguish the microscopic essence of the correlated superconductivity from the often spectacular phenomenology of the IPs. Here we introduce a model conceptual framework within which to understand the relationship between AF electron–electron interactions, IPs, and correlated SC. We demonstrate its effectiveness in simultaneously explaining the consequences of AF interactions for the copper-based, iron-based, and heavy-fermion superconductors, as well as for their quite distinct IPs. PMID:24114268
Simulation of Quantum Many-Body Dynamics for Generic Strongly-Interacting Systems
Meyer, Gregory; Machado, Francisco; Yao, Norman
2017-04-01
Recent experimental advances have enabled the bottom-up assembly of complex, strongly interacting quantum many-body systems from individual atoms, ions, molecules and photons. These advances open the door to studying dynamics in isolated quantum systems as well as the possibility of realizing novel out-of-equilibrium phases of matter. Numerical studies provide insight into these systems; however, computational time and memory usage limit common numerical methods such as exact diagonalization to relatively small Hilbert spaces of dimension 215 . Here we present progress toward a new software package for dynamical time evolution of large generic quantum systems on massively parallel computing architectures. By projecting large sparse Hamiltonians into a much smaller Krylov subspace, we are able to compute the evolution of strongly interacting systems with Hilbert space dimension nearing 230. We discuss and benchmark different design implementations, such as matrix-free methods and GPU based calculations, using both pre-thermal time crystals and the Sachdev-Ye-Kitaev model as examples. We also include a simple symbolic language to describe generic Hamiltonians, allowing simulation of diverse quantum systems without any modification of the underlying C and Fortran code.
International Nuclear Information System (INIS)
Recami, E.; Tonin Zanchin, V.; Martinez, J.M.
1986-01-01
A unified geometrical approach to strong and gravitational interactions has been recently proposed, based on the classical methods of General Relativity. According to it, hadrons can be regarded as black-hole type solutions of new field equations describing two tensorial metric-field (the ordinary gravitational field, and the strong one). In this paper, we first seize the opportunity for an improved exposition of some elements of the theory relevant to our present scope. Secondly, by extending the Bekenstein-Hawking thermodynamics to the above mentioned strong black-holes (SBH), it is shown: 1) that SBH thermodynamics seems to require a new expansion of our cosmos after its Big Crunch (i.e. that a recontraction of our cosmos has to be followed by a new creation); 2) that a collapsing star with mass M approximately in the range 3 to 5 solar masses, once reached the neutron-star density, could re-explode tending to form a (radiating) object with a diameter of the order of 1 light-day: thus failing to create a gravitational black-hole
Kovalev, Vadim M.; Tse, Wang-Kong
2017-11-01
We develop a microscopic theory for the relaxation dynamics of an optically pumped two-level system (TLS) coupled to a bath of weakly interacting Bose gas. Using Keldysh formalism and diagrammatic perturbation theory, expressions for the relaxation times of the TLS Rabi oscillations are derived when the boson bath is in the normal state and the Bose–Einstein condensate (BEC) state. We apply our general theory to consider an irradiated quantum dot coupled with a boson bath consisting of a two-dimensional dipolar exciton gas. When the bath is in the BEC regime, relaxation of the Rabi oscillations is due to both condensate and non-condensate fractions of the bath bosons for weak TLS-light coupling and pre dominantly due to the non-condensate fraction for strong TLS-light coupling. Our theory also shows that a phase transition of the bath from the normal to the BEC state strongly influences the relaxation rate of the TLS Rabi oscillations. The TLS relaxation rate is approximately independent of the pump field frequency and monotonically dependent on the field strength when the bath is in the low-temperature regime of the normal phase. Phase transition of the dipolar exciton gas leads to a non-monotonic dependence of the TLS relaxation rate on both the pump field frequency and field strength, providing a characteristic signature for the detection of BEC phase transition of the coupled dipolar exciton gas.
Tubman, Norm; Whaley, Birgitta
The development of exponential scaling methods has seen great progress in tackling larger systems than previously thought possible. One such technique, full configuration interaction quantum Monte Carlo, allows exact diagonalization through stochastically sampling of determinants. The method derives its utility from the information in the matrix elements of the Hamiltonian, together with a stochastic projected wave function, which are used to explore the important parts of Hilbert space. However, a stochastic representation of the wave function is not required to search Hilbert space efficiently and new deterministic approaches have recently been shown to efficiently find the important parts of determinant space. We shall discuss the technique of Adaptive Sampling Configuration Interaction (ASCI) and the related heat-bath Configuration Interaction approach for ground state and excited state simulations. We will present several applications for strongly correlated Hamiltonians. This work was supported through the Scientific Discovery through Advanced Computing (SciDAC) program funded by the U.S. Department of Energy, Office of Science, Advanced Scientific Computing Research and Basic Energy Sciences.
Lu, Xingyu; Zhang, Huilan; Lu, Manman; Vega, Alexander J; Hou, Guangjin; Polenova, Tatyana
2016-02-07
Experimental characterization of one-bond heteronuclear dipolar couplings is essential for structural and dynamics characterization of molecules by solid-state NMR. Accurate measurement of heteronuclear dipolar tensor parameters in magic-angle spinning NMR requires that the recoupling sequences efficiently reintroduce the desired heteronuclear dipolar coupling term, fully suppress other interactions (such as chemical shift anisotropy and homonuclear dipolar couplings), and be insensitive to experimental imperfections, such as radio frequency (rf) field mismatch. In this study, we demonstrate that the introduction of window delays into the basic elements of a phase-alternating R-symmetry (PARS) sequence results in a greatly improved protocol, termed windowed PARS (wPARS), which yields clean dipolar lineshapes that are unaffected by other spin interactions and are largely insensitive to experimental imperfections. Higher dipolar scaling factors can be attained in this technique with respect to PARS, which is particularly useful for the measurement of relatively small dipolar couplings. The advantages of wPARS are verified experimentally on model molecules N-acetyl-valine (NAV) and a tripeptide Met-Leu-Phe (MLF). The incorporation of wPARS into 3D heteronuclear or homonuclear correlation experiments permits accurate site-specific determination of dipolar tensors in proteins, as demonstrated on dynein light chain 8 (LC8). Through 3D wPARS recoupling based spectroscopy we have determined both backbone and side chain dipolar tensors in LC8 in a residue-resolved manner. We discuss these in the context of conformational dynamics of LC8. We have addressed the effect of paramagnetic relaxant Cu(ii)-EDTA doping on the dipolar coupling parameters in LC8 and observed no significant differences with respect to the neat sample permitting fast data collection. Our results indicate that wPARS is advantageous with respect to the windowless version of the sequence and is applicable
Studies of the strong and electroweak interactions at the Z^{0} pole
Energy Technology Data Exchange (ETDEWEB)
Hildreth, Michael Douglas [Stanford Univ., CA (United States)
1995-03-01
This thesis presents studies of the strong and electroweak forces, two of the fundamental interactions that govern the behavior of matter at high energies. The authors have used the hadronic decays of Z^{0} bosons produced with the unique experimental apparatus of the e^{+}e^{-} Linear Collider at the Stanford Linear Accelerator Center (SLAC) and the SLAC Large Detector (SLD) for these measurements. Employing the precision tracking capabilities of the SLD, they isolated samples of Z^{0} events containing primarily the decays of the Z^{0} to a chosen quark type. With an inclusive selection technique, they have tested the flavor independence of the strong coupling, α_{s} by measuring the rates of multi-jet production in isolated samples of light (uds), c, and b quark events. They find: α$s\\atop{uds}$/α$s\\atop{all}$ 0.987 ± 0.027(stat) ± 0.022(syst) ± 0.022(theory), α$c\\atop{s}$/α$all\\atop{s}$ = 1.012 ± 0.104(stat) ± 0.102(syst) ± 0.096(theory), α$b\\atop{s}$/α$all\\atop{s}$ = 1.026 {+-} 0.041(stat) ± 0.030(theory), which implies that the strong interaction is independent of quark flavor within the present experimental sensitivity. They have also measured the extent of parity-violation in the Z^{0} c$\\bar{c}$ coupling, given by the parameter A $0\\atop{c}$, using a sample of fully and partially reconstructed D* and D^{+} meson decays and the longitudinal polarization of the SLC electron beam. This sample of charm quark events was derived with selection techniques based on their kinematic properties and decay topologies. They find A$0\\atop{c}$ = 0.73 ± 0.22(stat) ± 0.10(syst). This value is consistent with that expected in the electroweak standard model of particle interactions.
Uniform strongly interacting soliton gas in the frame of the Nonlinear Schrodinger Equation
Gelash, Andrey; Agafontsev, Dmitry
2017-04-01
The statistical properties of many soliton systems play the key role in the fundamental studies of integrable turbulence and extreme sea wave formation. It is well known that separated solitons are stable nonlinear coherent structures moving with constant velocity. After collisions with each other they restore the original shape and only acquire an additional phase shift. However, at the moment of strong nonlinear soliton interaction (i.e. when solitons are located close) the wave field are highly complicated and should be described by the theory of inverse scattering transform (IST), which allows to integrate the KdV equation, the NLSE and many other important nonlinear models. The usual approach of studying the dynamics and statistics of soliton wave field is based on relatively rarefied gas of solitons [1,2] or restricted by only two-soliton interactions [3]. From the other hand, the exceptional role of interacting solitons and similar coherent structures - breathers in the formation of rogue waves statistics was reported in several recent papers [4,5]. In this work we study the NLSE and use the most straightforward and general way to create many soliton initial condition - the exact N-soliton formulas obtained in the theory of the IST [6]. We propose the recursive numerical scheme for Zakharov-Mikhailov variant of the dressing method [7,8] and discuss its stability with respect to increasing the number of solitons. We show that the pivoting, i.e. the finding of an appropriate order for recursive operations, has a significant impact on the numerical accuracy. We use the developed scheme to generate statistical ensembles of 32 strongly interacting solitons, i.e. solve the inverse scattering problem for the high number of discrete eigenvalues. Then we use this ensembles as initial conditions for numerical simulations in the box with periodic boundary conditions and study statics of obtained uniform strongly interacting gas of NLSE solitons. Author thanks the
Modeling a nonperturbative spinor vacuum interacting with a strong gravitational wave
Energy Technology Data Exchange (ETDEWEB)
Dzhunushaliev, Vladimir [Al-Farabi Kazakh National University, Department of Theoretical and Nuclear Physics, Almaty (Kazakhstan); Al-Farabi Kazakh National University, Institute of Experimental and Theoretical Physics, Almaty (Kazakhstan); Folomeev, Vladimir [Institute of Physicotechnical Problems and Material Science, NAS of the Kyrgyz Republic, Bishkek (Kyrgyzstan)
2015-07-15
We consider the propagation of strong gravitational waves interacting with a nonperturbative vacuum of spinor fields. To described the latter, we suggest an approximate model. The corresponding Einstein equation has the form of the Schroedinger equation. Its gravitational-wave solution is analogous to the solution of the Schroedinger equation for an electron moving in a periodic potential. The general solution for the periodic gravitational waves is found. The analog of the Kronig-Penney model for gravitational waves is considered. It is shown that the suggested gravitational-wave model permits the existence of weak electric charge and current densities concomitant with the gravitational wave. Based on this observation, a possible experimental verification of the model is suggested. (orig.)
Phase transitions, nonequilibrium dynamics, and critical behavior of strongly interacting systems
Energy Technology Data Exchange (ETDEWEB)
Mottola, E.; Bhattacharya, T.; Cooper, F. [and others
1998-12-31
This is the final report of a three-year, Laboratory Directed Research and Development project at Los Alamos National Laboratory. In this effort, large-scale simulations of strongly interacting systems were performed and a variety of approaches to the nonequilibrium dynamics of phase transitions and critical behavior were investigated. Focus areas included (1) the finite-temperature quantum chromodynamics phase transition and nonequilibrium dynamics of a new phase of matter (the quark-gluon plasma) above the critical temperature, (2) nonequilibrium dynamics of a quantum fields using mean field theory, and (3) stochastic classical field theoretic models with applications to spinodal decomposition and structural phase transitions in a variety of systems, such as spin chains and shape memory alloys.
Description of meson strong weak and electromagnetic interactions in quantum chiral theory
International Nuclear Information System (INIS)
Volkov, M.K.; Ehbert, D.
1979-01-01
The picture of all the principal meson decays of the basic octet has been obtained in the framework of the SU(3)xSU(3) symmetric chiral model of the field theory. An attempt is made to generalize the nonlinear chiral model for the case of charmed hadrons, i.e., a transition from the SU(3)xSU(3) group to the SU(4)xSU(4) group. The authors have succeeded in elucidating unambiguously the role of the Kabibbo angle both in weak and strong interactions (it defines the structure of weak hadron currents and hadron mass splitting in isotopic multiplets). Proceeding from decays of the basic octet mesons it has been shown that the nonlinear chiral SU(3)xSU(3) symmetric theory may be considered as the quantum field theory, which satisfactorily describes the low-energy meson physics in two first orders of the perturbation theory (tree and single-loop approximations)
Particle-Hole Character of the Higgs and Goldstone Modes in Strongly Interacting Lattice Bosons
Di Liberto, M.; Recati, A.; Trivedi, N.; Carusotto, I.; Menotti, C.
2018-02-01
We study the low-energy excitations of the Bose-Hubbard model in the strongly interacting superfluid phase using a Gutzwiller approach. We extract the single-particle and single-hole excitation amplitudes for each mode and report emergent mode-dependent particle-hole symmetry on specific arc-shaped lines in the phase diagram connecting the well-known Lorentz-invariant limits of the Bose-Hubbard model. By tracking the in-phase particle-hole symmetric oscillations of the order parameter, we provide an answer to the long-standing question about the fate of the pure amplitude Higgs mode away from the integer-density critical point. Furthermore, we point out that out-of-phase symmetric oscillations in the gapless Goldstone mode are responsible for a full suppression of the condensate density oscillations. Possible detection protocols are also discussed.
Magnetism and local symmetry breaking in a Mott insulator with strong spin orbit interactions.
Lu, L; Song, M; Liu, W; Reyes, A P; Kuhns, P; Lee, H O; Fisher, I R; Mitrović, V F
2017-02-09
Study of the combined effects of strong electronic correlations with spin-orbit coupling (SOC) represents a central issue in quantum materials research. Predicting emergent properties represents a huge theoretical problem since the presence of SOC implies that the spin is not a good quantum number. Existing theories propose the emergence of a multitude of exotic quantum phases, distinguishable by either local point symmetry breaking or local spin expectation values, even in materials with simple cubic crystal structure such as Ba 2 NaOsO 6 . Experimental tests of these theories by local probes are highly sought for. Our local measurements designed to concurrently probe spin and orbital/lattice degrees of freedom of Ba 2 NaOsO 6 provide such tests. Here we show that a canted ferromagnetic phase which is preceded by local point symmetry breaking is stabilized at low temperatures, as predicted by quantum theories involving multipolar spin interactions.
Kanske, Philipp; Böckler, Anne; Trautwein, Fynn-Mathis; Parianen Lesemann, Franca H; Singer, Tania
2016-09-01
Although the processes that underlie sharing others' emotions (empathy) and understanding others' mental states (mentalizing, Theory of Mind) have received increasing attention, it is yet unclear how they relate to each other. For instance, are people who strongly empathize with others also more proficient in mentalizing? And (how) do the neural networks supporting empathy and mentalizing interact? Assessing both functions simultaneously in a large sample (N = 178), we show that people's capacities to empathize and mentalize are independent, both on a behavioral and neural level. Thus, strong empathizers are not necessarily proficient mentalizers, arguing against a general capacity of social understanding. Second, we applied dynamic causal modeling to investigate how the neural networks underlying empathy and mentalizing are orchestrated in naturalistic social settings. Results reveal that in highly emotional situations, empathic sharing can inhibit mentalizing-related activity and thereby harm mentalizing performance. Taken together, our findings speak against a unitary construct of social understanding and suggest flexible interplay of distinct social functions. © The Author (2016). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.
Observation of quantum-limited spin transport in strongly interacting two-dimensional Fermi gases
Olsen, Ben A.; Luciuk, Chris; Smale, Scott; Böttcher, Florian; Sharum, Haille; Trotzky, Stefan; Enss, Tilman; Thywissen, Joseph H.
2017-04-01
Conjectured quantum bounds on transport appear to be respected in many strongly interacting many-body systems. Since transport occurs as a system relaxes to equilibrium, many such bounds can be recast as an upper bound on the local relaxation rate kB T / ℏ . Systems saturating this ``Planckian'' bound lack well defined quasiparticles promoting transport. We measure the transport properties of 2D ultracold Fermi gases of 40K during transverse demagnetization in a magnetic field gradient. Using a phase-coherent spin-echo sequence, we distinguish bare spin diffusion from the Leggett-Rice effect, in which demagnetization is slowed by the precession of spin current around the local magnetization. When the 2D scattering length is tuned near an s-wave Feshbach resonance to be comparable to the inverse Fermi wave vector kF- 1 , we find that the bare transverse spin diffusivity reaches a minimum of 1 . 7(6) ℏ / m . Demagnetization is also reflected in the growth rate of the s-wave contact, observed using time-resolved rf spectroscopy. At unitarity, the contact rises to 0 . 28(3) kF2 per particle, measuring the breaking of scaling symmetry. Our observations support the conjecture that under strong scattering, the local relaxation rate is bounded from above by kB T / ℏ .
Dipolar dark matter with massive bigravity
International Nuclear Information System (INIS)
Blanchet, Luc; Heisenberg, Lavinia
2015-01-01
Massive gravity theories have been developed as viable IR modifications of gravity motivated by dark energy and the problem of the cosmological constant. On the other hand, modified gravity and modified dark matter theories were developed with the aim of solving the problems of standard cold dark matter at galactic scales. Here we propose to adapt the framework of ghost-free massive bigravity theories to reformulate the problem of dark matter at galactic scales. We investigate a promising alternative to dark matter called dipolar dark matter (DDM) in which two different species of dark matter are separately coupled to the two metrics of bigravity and are linked together by an internal vector field. We show that this model successfully reproduces the phenomenology of dark matter at galactic scales (i.e. MOND) as a result of a mechanism of gravitational polarisation. The model is safe in the gravitational sector, but because of the particular couplings of the matter fields and vector field to the metrics, a ghost in the decoupling limit is present in the dark matter sector. However, it might be possible to push the mass of the ghost beyond the strong coupling scale by an appropriate choice of the parameters of the model. Crucial questions to address in future work are the exact mass of the ghost, and the cosmological implications of the model
New precision era of experiments on strong interaction with strangeness at DAFNE/LNF-INFN
Directory of Open Access Journals (Sweden)
Ishiwatari T.
2014-03-01
Full Text Available The strong-interaction shifts and widths of kaonic hydrogen, deuterium, 3He, and 4He were measured in the SIDDHARTA experiment. The most precise values of the shift and width of the kaonic hydrogen 1s state were determined to be ϵ1s = −283 ± 36(stat±6(syst eV and Γ1s = 541±89(stat±22(syst eV. The upper limit of the kaonic deuterium Kα yield was found to be ≤ 0.39%. In addition, the shifts and widths of the kaonic 3He and 4He 2p states were determined to be ϵ2p(3He = −2 ± 2(stat ± 4(syst eV and Γ2p(3He = 6 ± 6(stat ± 7(syst eV; ϵ2p(4He = +5 ± 3(stat ± 4(syst eV and Γ2p(4He = 14 ± 8(stat ± 5(syst eV. These values are important for the constraints of the low-energy K¯N$\\bar KN$ interaction in theoretical approaches.
Interaction of a strong stellar wind with a mutiphase interstellar medium
International Nuclear Information System (INIS)
Wolff, M.T.
1986-01-01
The interaction of a strong stellar wind with the interstellar medium produces a hot, low density cavity surrounded by a swept-up shell of gas. This cavity-plus-shell structure is collectively called an interstellar bubble. In calculations prior to this work, researchers assumed that the interstellar medium surrounding the wind-blowing star was described by a constant density and temperature (i.e., was homogeneous). This dissertation improves on these earlier calculations by assuming that the interstellar medium surrounding the star is inhomogeneous or multiphase. Gas flows are modeled by assuming that the inhomogeneous phases of the interstellar medium (the clouds) and the intercloud gas form two distinct but interacting fluid that can exchange mass momentum and energy with each other. In one set of calculations, it is assumed that thermal conductive evaporation of clouds brought about by the clouds sitting inside a region of hot (T ≅ 10 6 K) gas is the only mass exchange process operation between the clouds and intercloud fluid. It was found that the mass injection from the clouds to the intercloud gas via the process of thermal evaporation can significantly modify the structure of the interstellar bubble from that found in previous studies
Role of strongly interacting additives in tuning the structure and properties of polymer systems
Daga, Vikram Kumar
Block copolymer (BCP) nanocomposites are an important class of hybrid materials in which the BCP guides the spatial location and the periodic assembly of the additives. High loadings of well-dispersed nanofillers are generally important for many applications including mechanical reinforcing of polymers. In particular the composites shown in this work might find use as etch masks in nanolithography, or for enabling various phase selective reactions for new materials development. This work explores the use of hydrogen bonding interactions between various additives (such as homopolymers and non-polymeric additives) and small, disordered BCPs to cause the formation of well-ordered morphologies with small domains. A detailed study of the organization of homopolymer chains and the evolution of structure during the process of ordering is performed. The results demonstrate that by tuning the selective interaction of the additive with the incorporating phase of the BCP, composites with significantly high loadings of additives can be formed while maintaining order in the BCP morphology. The possibility of high and selective loading of additives in one of the phases of the ordered BCP composite opens new avenues due to high degree of functionalization and the proximity of the additives within the incorporating phase. This aspect is utilized in one case for the formation of a network structure between adjoining additive cores to derive mesoporous inorganic materials with their structures templated by the BCP. The concept of additive-driven assembly is extended to formulate BCPadditive blends with an ability to undergo photo-induced ordering. Underlying this strategy is the ability to transition a weakly interacting additive to its strongly interacting form. This strategy provides an on-demand, non-intrusive route for formation of well-ordered nanostructures in arbitrarily defined regions of an otherwise disordered material. The second area explored in this dissertation deals
Lau, K; Barlow, A; Moxey, G J; Li, Q; Liu, Y; Humphrey, M G; Cifuentes, M P; Frankcombe, T J; Stranger, R
2015-04-28
Dipolar molecular crystals present different physical properties from traditionally strongly correlated ionic solid-state inorganic crystals due to the weak intermolecular bonding. Herein, centrosymmetric dipolar molecular crystals of the organoruthenium complex trans-[Ru(C≡CC6H4-4-NO2)(C≡CPh)(dppe)2] [dppe = 1,2-bis(diphenylphosphino)ethane] display a large electric-field-induced strain behaving differently from conventional piezoelectric materials that must, structurally, be noncentrosymmetric. Further studies of related systematically varied crystalline organoruthenium complexes reveal that the strong electromechanical coupling effect is not from classical ferroelectricity, electrostriction, flexoelectricity or electrochemical strain. It is, instead, attributed to the disorder in the molecular packing, which facilitates reorientation of the molecular dipoles under the action of an applied electric field. This provides a fresh insight into the design and development of new functional materials and a promising source of electromechanical coupling in organometallic, and more generally dipolar molecular, crystals.
Advances in the Application of the Similarity Renormalization Group to Strongly Interacting Systems
Wendt, Kyle Andrew
The Similarity Renormalization Group (SRG) as applied in nuclear physics is a tool to soften and decouple inter-nucleon interactions. The necessity for such a tool is generated by the strong coupling of high- and low-momentum degrees of freedom in modern precision interactions. In recent years the SRG have been used with great success in enhancing few (2-12) nucleon calculations, but there are still many open questions about the nature of the SRG, and how it affects chiral forces. This thesis focuses on three topics within the study of the SRG as it applies to nuclear few-body interactions, with a focus on nuclear forces from chiral effective field theory. The typical SRG applied to nuclear physics is the T̂ rel-SRG, which uses the relative kinetic energy to generate a renormalizing flow. However, this generator explicitly violates criteria that ensure the SRG will decouple the interaction. Previous study of this generator found for a simple model that as the resolution is lowered past the momentum scales associated with a bound state, the T̂rel-SRG enhances coupling near the bound state whereas the classical Wegner generator completely decouples the bound state. In practice, this has not been an issue because the only two-body bound state is very shallow, and therefore well below the SRG softening scales. This study is extended to use leading order chiral effective field theory with large cutoffs to explore this decoupling. This builds in the same low energy physics while including spurious high energy details, including high energy bound states. The evolutions with T̂rel-SRG are compared to the evolution with Wegner's generator. During the decoupling process, the SRG can induce new non-local contributions to the interactions, which inhibits its application using Quantum Monte Carlo (QMC) methods. Separating out the non-local terms is numerically difficult. Instead an approximate separation is applied to T̂ rel-SRG evolved interactions and the nature of the
Numerical simulation of wave-current interaction under strong wind conditions
Larrañaga, Marco; Osuna, Pedro; Ocampo-Torres, Francisco Javier
2017-04-01
Although ocean surface waves are known to play an important role in the momentum and other scalar transfer between the atmosphere and the ocean, most operational numerical models do not explicitly include the terms of wave-current interaction. In this work, a numerical analysis about the relative importance of the processes associated with the wave-current interaction under strong off-shore wind conditions in Gulf of Tehuantepec (the southern Mexican Pacific) was carried out. The numerical system includes the spectral wave model WAM and the 3D hydrodynamic model POLCOMS, with the vertical turbulent mixing parametrized by the kappa-epsilon closure model. The coupling methodology is based on the vortex-force formalism. The hydrodynamic model was forced at the open boundaries using the HYCOM database and the wave model was forced at the open boundaries by remote waves from the southern Pacific. The atmospheric forcing for both models was provided by a local implementation of the WRF model, forced at the open boundaries using the CFSR database. The preliminary analysis of the model results indicates an effect of currents on the propagation of the swell throughout the study area. The Stokes-Coriolis term have an impact on the transient Ekman transport by modifying the Ekman spiral, while the Stokes drift has an effect on the momentum advection and the production of TKE, where the later induces a deepening of the mixing layer. This study is carried out in the framework of the project CONACYT CB-2015-01 255377 and RugDiSMar Project (CONACYT 155793).
Critical Behavior of a Strongly-Interacting 2D Electron System
Sarachik, Myriam P.
2013-03-01
Two-dimensional (2D) electron systems that obey Fermi liquid theory at high electron densities are expected to undergo one or more transitions to spatially and/or spin-ordered phases as the density is decreased, ultimately forming a Wigner crystal in the dilute, strongly-interacting limit. Interesting, unexpected behavior is observed with decreasing electron density as the electrons' interactions become increasingly important relative to their kinetic energy: the resistivity undergoes a transition from metallic to insulating temperature dependence; the resistance increases sharply and then saturates abruptly with increasing in-plane magnetic field; a number of experiments indicate that the electrons' effective mass exhibits a substantial increase approaching a finite ``critical'' density. There has been a great deal of debate concerning the underlying physics in these systems, and many have questioned whether the change of the resistivity from metallic to insulating signals a phase transition or a crossover. In this talk, I will report measurements that show that with decreasing density ns, the thermopower S of a low-disorder 2D electron system in silicon exhibits a sharp increase by more than an order of magnitude, tending to a divergence at a finite, disorder-independent density nt, consistent with the critical form (- T / S) ~(ns -nt) x with x = 1 . 0 +/- 0 . 1 (T is the temperature). Unlike the resistivity which may not clearly distinguish between a transition and crossover behavior, the thermopower provides clear evidence that a true phase transition occurs with decreasing density to a new low-density phase. Work supported by DOE Grant DE-FG02-84ER45153, BSF grant 2006375, RFBR, RAS, and the Russian Ministry of Science.
Longitudinal expansion of field line dipolarization
Saka, O.; Hayashi, K.
2017-11-01
We examine the substorm expansions that started at 1155 UT 10 August 1994 in the midnight sector focusing on the longitudinal (eastward) expansion of field line dipolarization in the auroral zone. Eastward expansion of the dipolarization region was observed in all of the H, D, and Z components. The dipolarization that started at 1155 UT (0027 MLT) from 260° of geomagnetic longitude (CMO) expanded to 351°(PBQ) in about 48 min. The expansion velocity was 0.03-0.04°/s, or 1.9 km/s at 62°N of geomagnetic latitude. The dipolarization region expanding to the east was accompanied by a bipolar event at the leading edge of the expansion in latitudes equatorward of the westward electrojet (WEJ). In the midnight sector at the onset meridian, the Magnetospheric Plasma Analyzer (MAP) on board geosynchronous satellite L9 measured electrons and ions between 10 eV and 40 keV. We conclude from the satellite observations that this dipolarization was characterized by the evolution of temperature anisotropies, an increase of the electron and ion temperatures, and a rapid change in the symmetry axis of the temperature tensor. The field line dipolarization and its longitudinal expansion were interpreted in terms of the slow MHD mode triggered by the current disruption. We propose a new magnetosphere-ionosphere coupling (MI-coupling) mechanism based on the scenario that transmitted westward electric fields from the magnetosphere in association with expanding dipolarization produced electrostatic potential (negative) in the ionosphere through differences in the mobility of collisional ions and collisionless electrons. The field-aligned currents that emerged from the negative potential region are arranged in a concentric pattern around the negative potential region, upward toward the center and downward on the peripheral.
Magnetic holes in the dipolarized magnetotail: ion and electron anisotropies
Shustov, P.; Artemyev, A.; Zhang, X. J.; Yushkov, E.; Petrukovich, A. A.
2017-12-01
We conduct statistics on magnetic holes observed by THEMIS spacecraft in the near-Earth magnetotail. Groups of holes are detected after dipolarizations in the quiet, equatorial plasma sheet. Magnetic holes are characterized by significant magnetic field depressions (up to 50%) and strong electron currents ( 10-50 nA/m2), with spatial scales much smaller than the ion gyroradius. These magnetic holes are populated by hot (>10 keV), transversely anisotropic electrons supporting the pressure balance. We present statistical properties of these sub-ion scale magnetic holes and discuss possible mechanisms on the hole formation.
Strongly self-interacting vector dark matter via freeze-in
Duch, Mateusz; Grzadkowski, Bohdan; Huang, Da
2018-01-01
We study a vector dark matter (VDM) model in which the dark sector couples to the Standard Model sector via a Higgs portal. If the portal coupling is small enough the VDM can be produced via the freeze-in mechanism. It turns out that the electroweak phase transition have a substantial impact on the prediction of the VDM relic density. We further assume that the dark Higgs boson which gives the VDM mass is so light that it can induce strong VDM self-interactions and solve the small-scale structure problems of the Universe. As illustrated by the latest LUX data, the extreme smallness of the Higgs portal coupling required by the freeze-in mechanism implies that the dark matter direct detection bounds are easily satisfied. However, the model is well constrained by the indirect detections of VDM from BBN, CMB, AMS-02, and diffuse γ/X-rays. Consequently, only when the dark Higgs boson mass is at most of O (keV) does there exist a parameter region which leads to a right amount of VDM relic abundance and an appropriate VDM self-scattering while satisfying all other constraints simultaneously.
Strongly interacting Fermi systems in 1/N expansion: From cold atoms to color superconductivity
International Nuclear Information System (INIS)
Abuki, Hiroaki; Brauner, Tomas
2008-01-01
We investigate the 1/N expansion proposed recently as a strategy to include quantum fluctuation effects in the nonrelativistic, attractive Fermi gas at and near unitarity. We extend the previous results by calculating the next-to-leading order corrections to the critical temperature along the whole crossover from Bardeen-Cooper-Schrieffer (BCS) superconductivity to Bose-Einstein condensation. We demonstrate explicitly that the extrapolation from the mean-field approximation, based on the 1/N expansion, provides a useful approximation scheme only on the BCS side of the crossover. We then apply the technique to the study of strongly interacting relativistic many-fermion systems. Having in mind the application to color superconductivity in cold dense quark matter, we develop, within a simple model, a formalism suitable to compare the effects of order parameter fluctuations in phases with different pairing patterns. Our main conclusion is that the relative correction to the critical temperature is to a good accuracy proportional to the mean-field ratio of the critical temperature and the chemical potential. As a consequence, it is significant even rather deep in the BCS regime, where phenomenologically interesting values of the quark-quark coupling are expected. Possible impact on the phase diagram of color-superconducting quark matter is discussed.
Three-dimensional RAGE Simulations of Strong Shocks Interacting with Sapphire Balls
Wilde, B. H.; Coker, R. F.; Rosen, P. A.; Foster, J. M.; Hartigan, P.; Carver, R.; Blue, B. E.; Hansen, J. F.
2007-11-01
The goal of our 2007-2008 NLUF experiments at the OMEGA laser facility is to investigate the physics associated with the interaction of strong shocks and jets with clumpy media. These experiments have close analogs with structures observed in a variety of astrophysical flows, including jets from young stars, outflows from planetary nebulae, and extragalactic jets. In these experiments, a multi-mega bar shock is created in a plastic layer by heating a hohlraum to 190 eV temperature with 5 kJ of laser energy. The shock enters a 0.3 g/cc RF foam into which are embedded 500 micron diameter sapphire balls. The shock shears off the ball such that it creates thin two-dimensional sheets of sapphire which subsequently break up and undergo the three-dimensional Widnall instability (Widnall, S. E., Bliss, D. B., & Tsai, C. 1974, J. Fluid Mech., 66, 35). The time evolution of the ball/balls is diagnosed with dual-axes point-projection radiography. In this poster, we discuss the results of high-resolution three-dimensional radiation-hydrodynamic simulations with the adaptive-mesh-refinement RAGE code of single and multiple balls. Comparisons with data from our August shots will be made.
Introduction to gauge theories of the strong, weak, and electromagnetic interactions
International Nuclear Information System (INIS)
Quigg, C.
1980-07-01
The plan of these notes is as follows. Chapter 1 is devoted to a brief evocative review of current beliefs and prejudices that form the context for the discussion to follow. The idea of Gauge Invariance is introduced in Chapter 2, and the connection between conservation laws and symmetries of the Lagrangian is recalled. Non-Abelian gauge field theories are constructed in Chapter 3, by analogy with the familiar case of electromagnetism. The Yang-Mills theory based upon isospin symmetry is constructed explicitly, and the generalization is made to other gauge groups. Chapter 4 is concerned with spontaneous symmetry breaking and the phenomena that occur in the presence or absence of local gauge symmetries. The existence of massless scalar fields (Goldstone particles) and their metamorphosis by means of the Higgs mechanism are illustrated by simple examples. The Weinberg-Salam model is presented in Chapter 5, and a brief resume of applications to experiment is given. Quantum Chromodynamics, the gauge theory of colored quarks and gluons, is developed in Chapter 6. Asymptotic freedom is derived schematically, and a few simple applications of perturbative QCD ae exhibited. Details of the conjectured confinement mechanism are omitted. The strategy of grand unified theories of the strong, weak, and electromagnetic interactions is laid out in Chapter 7. Some properties and consequences of the minimal unifying group SU(5) are presented, and the gauge hierarchy problem is introduced in passing. The final chapter contains an essay on the current outlook: aspirations, unanswered questions, and bold scenarios
International Nuclear Information System (INIS)
Dubovitskii, V.A.; Pavlov, G.A.; Krasnikov, Yu.G.
1996-01-01
Thermodynamic analysis of media with strong interparticle (Coulomb) interaction is presented. A method for constructing isotherms is proposed for a medium described by a closed multicomponent thermodynamic model. The method is based on choosing an appropriate nondegenerate frame of reference in the extended space of thermodynamic variables and provides efficient thermodynamic calculations in a wide range of parameters, for an investigation of phase transitions of the first kind, and for determining both the number of phases and coexistence curves. A number of approximate thermodynamic models of hydrogen plasma are discussed. The approximation corresponding to the n5/2 law, in which the effects of particle attraction and repulsion are taken into account qualitatively, is studied. This approximation allows studies of thermodynamic properties of a substance for a wide range of parameters. In this approximation, for hydrogen at a constant temperature, various properties of the degree of ionization are revealed. In addition, the parameters of the second critical point are found under conditions corresponding to the Jovian interior
Ground state configurations in antiferromagnetic ultrathin films with dipolar anisotropy
Energy Technology Data Exchange (ETDEWEB)
Leon, H., E-mail: hleon@imre.oc.uh.cu [Instituto de Ciencia y Tecnologia de Materiales, Universidad de La Habana, Zapata e/ Mazon y G. Vedado, 10400 La Habana (Cuba)
2013-02-15
The formalism developed in a previous work to calculate the dipolar energy in quasi-two-dimensional crystals with ferromagnetic order is now extended to collinear antiferromagnetic order. Numerical calculations of the dipolar energy are carried out for systems with tetragonally distorted fcc [001] structures, the case of NiO and MnO ultrathin film grown in non-magnetic substrates, where the magnetic phase is a consequence of superexchange and dipolar interactions. The employed approximation allows to demonstrate that dipolar coupling between atomic layers is responsible for the orientation of the magnetization when it differs from the one in a single layer. The ground state energy of a given NiO or MnO film is found to depend not only on the strain, but also on how much the interlayer separation and the 2D lattice constant are changed with respect to the ideal values corresponding to the non-distorted cubic structure. Nevertheless, it is shown that the orientation of the magnetization in the magnetic phase of any of these films is determined by the strain exclusively. A striped phase with the magnetization along the [112{sup Macron }] direction appears as the ground state configuration of NiO and MnO ultrathin films. In films with equally oriented stripes along the layers this magnetic phase is twofold degenerate, while in films with multidomain layers it is eightfold degenerate. These results are not in contradiction with experimentally observed out-of-plane or in-plane magnetization of striped phases in NiO and MnO ultrathin films. - Highlights: Black-Right-Pointing-Pointer Dipolar energy in collinear antiferromagnetic ultrathin films is calculated. Black-Right-Pointing-Pointer Numerical results are presented for distorted fcc [001] structures. Black-Right-Pointing-Pointer The lowest energy of a system depends on how the tetragonal distortion is achieved. Black-Right-Pointing-Pointer A striped phase with magnetization in the [112{sup Macron }] direction is the
Ground state configurations in antiferromagnetic ultrathin films with dipolar anisotropy
International Nuclear Information System (INIS)
León, H.
2013-01-01
The formalism developed in a previous work to calculate the dipolar energy in quasi-two-dimensional crystals with ferromagnetic order is now extended to collinear antiferromagnetic order. Numerical calculations of the dipolar energy are carried out for systems with tetragonally distorted fcc [001] structures, the case of NiO and MnO ultrathin film grown in non-magnetic substrates, where the magnetic phase is a consequence of superexchange and dipolar interactions. The employed approximation allows to demonstrate that dipolar coupling between atomic layers is responsible for the orientation of the magnetization when it differs from the one in a single layer. The ground state energy of a given NiO or MnO film is found to depend not only on the strain, but also on how much the interlayer separation and the 2D lattice constant are changed with respect to the ideal values corresponding to the non-distorted cubic structure. Nevertheless, it is shown that the orientation of the magnetization in the magnetic phase of any of these films is determined by the strain exclusively. A striped phase with the magnetization along the [112 ¯ ] direction appears as the ground state configuration of NiO and MnO ultrathin films. In films with equally oriented stripes along the layers this magnetic phase is twofold degenerate, while in films with multidomain layers it is eightfold degenerate. These results are not in contradiction with experimentally observed out-of-plane or in-plane magnetization of striped phases in NiO and MnO ultrathin films. - Highlights: ► Dipolar energy in collinear antiferromagnetic ultrathin films is calculated. ► Numerical results are presented for distorted fcc [001] structures. ► The lowest energy of a system depends on how the tetragonal distortion is achieved. ► A striped phase with magnetization in the [112 ¯ ] direction is the ground state. ► In multidomain NiO and MnO films it is eightfold degenerate.
International Nuclear Information System (INIS)
Carruthers, P.; Thews, R.L.
1988-01-01
This paper contains progress information on the following topics in High Energy Physics: strong, electromagnetic, and weak interactions; aspects of quark-gluon models for hadronic interactions, decays, and structure; the dynamical generation of a mass gap and the role and truthfulness of perturbation theory; statistical and dynamical aspects of hadronic multiparticle production; and realization of chiral symmetry and temperature effects in supersymmetric theories
A Uniﬁed Theory of Interaction: Gravitation, Electrodynamics and the Strong Force
Directory of Open Access Journals (Sweden)
Wagener P.
2009-01-01
Full Text Available A unified model of gravitation and electromagnetism is extended to derive the Yukawa potential for the strong force. The model satisfies the fundamental characteristics of the strong force and calculates the mass of the pion.
Dipolar modulation of Large-Scale Structure
Yoon, Mijin
For the last two decades, we have seen a drastic development of modern cosmology based on various observations such as the cosmic microwave background (CMB), type Ia supernovae, and baryonic acoustic oscillations (BAO). These observational evidences have led us to a great deal of consensus on the cosmological model so-called LambdaCDM and tight constraints on cosmological parameters consisting the model. On the other hand, the advancement in cosmology relies on the cosmological principle: the universe is isotropic and homogeneous on large scales. Testing these fundamental assumptions is crucial and will soon become possible given the planned observations ahead. Dipolar modulation is the largest angular anisotropy of the sky, which is quantified by its direction and amplitude. We measured a huge dipolar modulation in CMB, which mainly originated from our solar system's motion relative to CMB rest frame. However, we have not yet acquired consistent measurements of dipolar modulations in large-scale structure (LSS), as they require large sky coverage and a number of well-identified objects. In this thesis, we explore measurement of dipolar modulation in number counts of LSS objects as a test of statistical isotropy. This thesis is based on two papers that were published in peer-reviewed journals. In Chapter 2 [Yoon et al., 2014], we measured a dipolar modulation in number counts of WISE matched with 2MASS sources. In Chapter 3 [Yoon & Huterer, 2015], we investigated requirements for detection of kinematic dipole in future surveys.
Multi-dipolar microwave plasmas and their application to negative ion production
Energy Technology Data Exchange (ETDEWEB)
Béchu, S.; Bès, A.; Lacoste, A. [LPSC, Université Joseph Fourier Grenoble 1, CNRS/IN2P3, Grenoble INP, 53, Avenue des Martyrs, 38026 Grenoble (France); Soum-Glaude, A. [LPSC, Université Joseph Fourier Grenoble 1, CNRS/IN2P3, Grenoble INP, 53, Avenue des Martyrs, 38026 Grenoble (France); PROMES/CNRS, Tecnosud, Rambla de la Thermodynamique, F-66100 Perpignan (France); Svarnas, P. [High Voltage Laboratory, Department of Electrical and Computer Engineering, University of Patras, 26504 Rion (Greece); Aleiferis, S. [LPSC, Université Joseph Fourier Grenoble 1, CNRS/IN2P3, Grenoble INP, 53, Avenue des Martyrs, 38026 Grenoble (France); High Voltage Laboratory, Department of Electrical and Computer Engineering, University of Patras, 26504 Rion (Greece); Ivanov, A. A. Jr.; Bacal, M. [UPMC, LPP, Ecole Polytechnique, Palaiseau, Université PARIS-SUD 11, UMR CNRS 7648 (France)
2013-10-15
During the past decade multi-dipolar plasmas have been employed for various purposes such as surface treatments in biomedicine, physical and chemical vapour deposition for hydrogen storage, and applications in mechanical engineering. On the other hand, due to the design and operational mode of these plasma sources (i.e., strong permanent magnets for the electron cyclotron resonance coupling, low working pressure, and high electron density achieved) they are suitable for studying fundamental mechanisms involved in negative ion sources used in magnetically confined fusion and particle accelerators. Thus, this study presents an overview of fundamental results obtained with: (i) a single dipolar source, (ii) a network of seven dipolar plasma sources inserted into a magnetic multipolar chamber (Camembert III), and (iii) four dipolar sources housed in a smaller metallic cylinder (ROSAE III). Investigations with Langmuir probes of electron energy probability functions revealed the variation of the plasma properties versus the radial distance from the axis of a dipolar source in its mid plane and allowed the determination of the proportion between hot and cold electron populations in both chambers. These results are compared with the density of hydrogen negative ions, measured using the photodetachment technique. Electron energy probability functions obtained in these different configurations show the possibility of both hot and cold electron production. The former is a prerequisite for increasing the vibrational level of molecules and the dissociation degree and the latter for producing negative ions via dissociative attachment of the cold electrons or via surface production induced by H atoms.
Multi-dipolar microwave plasmas and their application to negative ion production
Béchu, S.; Soum-Glaude, A.; Bès, A.; Lacoste, A.; Svarnas, P.; Aleiferis, S.; Ivanov, A. A.; Bacal, M.
2013-10-01
During the past decade multi-dipolar plasmas have been employed for various purposes such as surface treatments in biomedicine, physical and chemical vapour deposition for hydrogen storage, and applications in mechanical engineering. On the other hand, due to the design and operational mode of these plasma sources (i.e., strong permanent magnets for the electron cyclotron resonance coupling, low working pressure, and high electron density achieved) they are suitable for studying fundamental mechanisms involved in negative ion sources used in magnetically confined fusion and particle accelerators. Thus, this study presents an overview of fundamental results obtained with: (i) a single dipolar source, (ii) a network of seven dipolar plasma sources inserted into a magnetic multipolar chamber (Camembert III), and (iii) four dipolar sources housed in a smaller metallic cylinder (ROSAE III). Investigations with Langmuir probes of electron energy probability functions revealed the variation of the plasma properties versus the radial distance from the axis of a dipolar source in its mid plane and allowed the determination of the proportion between hot and cold electron populations in both chambers. These results are compared with the density of hydrogen negative ions, measured using the photodetachment technique. Electron energy probability functions obtained in these different configurations show the possibility of both hot and cold electron production. The former is a prerequisite for increasing the vibrational level of molecules and the dissociation degree and the latter for producing negative ions via dissociative attachment of the cold electrons or via surface production induced by H atoms.
Cluster Observations of Multiple Dipolarization Fronts
Hwang, Kyoung-Joo; Goldstein, Melvyn L.; Lee, Ensang; Pickett, Jolene S.
2011-01-01
We present Cluster observations of a series of dipolarization fronts (DF 1 to 6) at the central current sheet in Earth's magnetotail. The velocities of fast earthward flow following behind each DF 1-3, are comparable to the Alfven velocity, indicating that the flow bursts might have been generated by bursty reconnection that occurred tailward of the spacecraft. Based on multi-spacecraft timing analysis, DF normals are found to propagate mainly earthward at $160-335$ km/s with a thickness of 900-1500 km, which corresponds to the ion inertial length or gyroradius scale. Each DF is followed by significant fluctuations in the $x$ and $y$ components of the magnetic field whose peaks are found 1-2 minutes after the DF passage. These $(B_{x},B_{y} )$-fluctuations propagate dawnward (mainly) and earthward. Strongly enhanced field-aligned beams are observed coincidently with $(B_{x},B_{y})$ fluctuations, while an enhancement of cross-tail currents is associated with the DFs. From the observed pressure imbalance and flux-tube entropy changes between the two regions separated by the DF, we speculate that interchange instability destabilizes the DFs and causes the deformation of the mid-tail magnetic topology. This process generates significant field-aligned currents, and might power the auroral brightening in the ionosphere. However, this event is neither associated with the main substorm auroral breakup nor the poleward expansion, which might indicate that the observed multiple DFs have been dissipated before they reach the inner plasma sheet boundary.
Electron Jet Detected by MMS at Dipolarization Front
Liu, C. M.; Fu, H. S.; Vaivads, A.; Khotyaintsev, Y. V.; Gershman, D. J.; Hwang, K.-J.; Chen, Z. Z.; Cao, D.; Xu, Y.; Yang, J.; Peng, F. Z.; Huang, S. Y.; Burch, J. L.; Giles, B. L.; Ergun, R. E.; Russell, C. T.; Lindqvist, P.-A.; Le Contel, O.
2018-01-01
Using MMS high-resolution measurements, we present the first observation of fast electron jet (Ve 2,000 km/s) at a dipolarization front (DF) in the magnetotail plasma sheet. This jet, with scale comparable to the DF thickness ( 0.9 di), is primarily in the tangential plane to the DF current sheet and mainly undergoes the E × B drift motion; it contributes significantly to the current system at the DF, including a localized ring-current that can modify the DF topology. Associated with this fast jet, we observed a persistent normal electric field, strong lower hybrid drift waves, and strong energy conversion at the DF. Such strong energy conversion is primarily attributed to the electron-jet-driven current (E ṡ je ≈ 2 E ṡ ji), rather than the ion current suggested in previous studies.
Energy Technology Data Exchange (ETDEWEB)
Chan, J.; DePorcel, L.; Dixon, L. [eds.
1997-06-01
This conference explored the role of the strong interaction in the physics of hadrons and partons. The Institute attracted 239 physicists from 16 countries to hear lectures on the underlying theory of Quantum Chromodynamics, modern theoretical calculational techniques, and experimental investigation of the strong interaction as it appears in various phenomena. Different regimes in which one can calculate reliably in QCD were addressed in series of lectures on perturbation theory, lattice gauge theories, and heavy quark expansions. Studies of QCD in hadron-hadron collisions, electron-positron annihilation, and electron-proton collisions all give differing perspectives on the strong interaction--from low-x to high-Q{sup 2}. Experimental understanding of the production and decay of heavy quarks as well as the lighter meson states has continued to evolve over the past years, and these topics were also covered at the School. Selected papers have been indexed separately for inclusion in the Energy Science and Technology Database.
Dipolar Quinoidal Acene Analogues as Stable Isoelectronic Structures of Pentacene and Nonacene
Shi, Xueliang
2015-10-08
Quinoidal thia-acene analogues, as the respective isoelectronic structures of pentacene and nonacene, were synthesized and an unusual 1,2-sulfur migration was observed during the Friedel-Crafts alkylation reaction. The analogues display a closed-shell quinoidal structure in the ground state with a distinctive dipolar character. In contrast to their acene isoelectronic structures, both compounds are stable because of the existence of more aromatic sextet rings, a dipolar character, and kinetic blocking. They exhibit unique packing in single crystals resulting from balanced dipole-dipole and [C-H⋯π]/[C-H⋯S] interactions.
A variational approach to Bogoliubov excitations and dynamics of dipolar Bose–Einstein condensates
International Nuclear Information System (INIS)
Kreibich, Manuel; Main, Jörg; Wunner, Günter
2013-01-01
We investigate the stability properties and the dynamics of Bose–Einstein condensates with axial symmetry, especially with dipolar long-range interaction, using both simulations on grids and variational calculations. We present an extended variational ansatz which is applicable for axial symmetry and show that this ansatz can reproduce the lowest eigenfrequencies of the Bogoliubov spectrum, and also the corresponding eigenfunctions. Our variational ansatz is capable of describing the roton instability of pancake-shaped dipolar condensates for arbitrary angular momenta. After investigating the linear regime we apply the ansatz to determine the dynamics and show how the angular collapse is correctly described within the variational framework. (paper)
Dipolarization fronts in the near-Earth space and substorm dynamics
Directory of Open Access Journals (Sweden)
I. I. Vogiatzis
2015-01-01
Full Text Available During magnetospheric substorms and plasma transport in the Earth's magnetotail various magnetic structures can be detected. Dipolarization fronts and flux ropes are the most prominent structures characteristic for substorm dynamics. However, they are treated as separate magnetotail features independent of each other. In this paper, we analyze a number of dipolarization fronts observed by the THEMIS (Time History of Events and Macroscale Interactions during Substorms spacecraft at different geocentric distances by applying the magnetohydrostatic Grad–Shafranov (GS reconstruction technique. Our analysis shows that there is a possibility of dipolarization fronts to originate from highly dissipated flux ropes which are in the late stage of their evolution, subjected to a continuous magnetic deterioration due to the reconnection process. These results may improve our understanding of magnetoplasma processes in Earth's magnetotail.
International Nuclear Information System (INIS)
Santilli, R.M.
1981-01-01
A primary objective of the research is the achievement of clear experimental knowledge on the intrinsic characteristics of particles (such as magnetic moment, spin, space parity, etc.) under strong interactions. These characteristics, when known, have been measured a number of times, but all times for particles under long range electromagnetic interactions (e.g., for bubble chamber techniques). The same characteristics are then generally assumed to persist under the different physical conditions of the strong interactions, while no direct or otherwise final measurement under strong interactions exists at this time. The advocated physical knowledge is clearly important for controlled fusion, as well as for a serious study of the foundations of strong interactions. The paper initiates the study by considering the following alternatives. A: the electromagnetic characteristics of particles persist in the transition to the strong; or B: variations in these characteristics are physically conceivable, mathematically treatable, and experimentally detectable. The need to conduct additional experiments, and achieve a final resolution of the issue, is stressed throughout the paper. In the hope of contributing toward this future goal, the paper then reviews the quantitative treatment of possible deviations via the Lie-admissible generalization of Lie's theory, with particular reference to the Lie-admissible generalizations of Lie group, Lie algebras, and enveloping associative algebras. A generalized notion of extended particle under nonlocal nonpotential strong interactions emerge from these studies. The theory is applied to the re-elaboration of the data on the spinor symmetry via neutron interferometers. It is shown that the data are indeed consistent with a breaking of the SU(2)-spin symmetry due to nonlocal nonpotential forces. A number of experiments for the future resolution of the issue are indicated
Lyubarsky, Yuri
2018-02-01
This paper is the first in the series of papers aiming to study interaction of the electromagnetic precursor waves generated at the front of a relativistic shock with the upstream flow. It is motivated by a simple consideration showing that the absorption of such an electromagnetic precursor could yield an efficient transformation of the kinetic energy of the upstream flow to the energy of accelerated particles. Taking into account that the precursor is a strong wave, in which electrons oscillate with relativistic velocities, the standard plasma-radiation interaction processes should be reconsidered. In this paper, I calculate the synchrotron absorption of strong electromagnetic waves.
International Nuclear Information System (INIS)
Boreham, B. W.; Hora, H.
1997-01-01
We have recently developed a correspondence principle for electromagnetic interaction. When applied to laser interactions with electrons this correspondence principle identifies a critical laser intensity I*. This critical intensity is a transition intensity separating classical mechanical and quantum mechanical interaction regimes. In this paper we discuss the further application of I* to the interaction of bound electrons in atoms. By comparing I* with the ionisation threshold intensities as calculated from a cycle-averaged simple-atom model we conclude that I* can be usefully interpreted as a lower bound to the classical regime in studies of ionisation of gas atoms by intense laser beams
Wave Vector Dependent Susceptibility at T>Tc in a Dipolar Ising Ferromagnet
DEFF Research Database (Denmark)
Als-Nielsen, Jens Aage; Holmes, L. M:; Guggenheim, H. J.
1974-01-01
The wave-vector-dependent susceptibility of LiTbF4 has been investigated by means of neutron scattering. The observations show a singularity of the susceptibility near wave vector Q=0 which is characteristic of the dipolar Coulomb interaction and good agreement with theory is obtained...
Classical Fractals and Quantum Chaos in Ultracold Dipolar Collisions.
Yang, B C; Pérez-Ríos, Jesús; Robicheaux, F
2017-04-14
We examine a dipolar-gas model to address fundamental issues regarding the correspondence between classical chaos and quantum observations in ultracold dipolar collisions. The theoretical model consists of a short-range Lennard-Jones potential well with an anisotropic, long-range dipole-dipole interaction between two atoms. Both the classical and quantum dynamics are explored for the same Hamiltonian of the system. The classical chaotic scattering is revealed by the fractals developed in the scattering function (defined as the final atom separation as a function of initial conditions), while the quantum chaotic features lead to the repulsion of the eigenphases from the corresponding quantum S matrix. The nearest-eigenphase-spacing statistics have an intermediate behavior between the Poisson and the Wigner-Dyson distributions. The character of the distribution can be controlled by changing an effective Planck constant or the dipole moment. The degree of quantum chaos shows a good correspondence with the overall average of the classical scattering function. The results presented here also provide helpful insights for understanding the role of the inherent dipole-dipole interaction in the currently ongoing experiments on ultracold collisions of highly magnetic atoms.
Dipolar structures in colloidal magnetite dispersions
Klokkenburg, Mark
2007-01-01
Dipolar structures in liquid colloidal dispersions comprising well-defined magnetite (Fe3O4) nanoparticles with a permanent magnetic dipole moment are analyzed on a single-particle level by in situ cryogenic transmission electron microscopy (2D). Compared to conventional ferrofluids, these
Use of quadrupolar and dipolar couplings
Indian Academy of Sciences (India)
Abstract. Use of dipolar and quadrupolar couplings for quantum information processing (QIP) by nuclear magnetic resonance (NMR) is described. In these cases, instead of the individual spins being qubits, the 2n energy levels of the spin-system can be treated as an n-qubit system. It is demonstrated that QIP in such ...
Uncovering new strong dynamics via topological interactions at the 100 TeV collider
DEFF Research Database (Denmark)
Molinaro, Emiliano; Sannino, Francesco; Thomsen, Anders Eller
2017-01-01
In models of composite Higgs dynamics, new composite pseudoscalars can interact with the Higgs and electroweak gauge bosons via anomalous interactions, stemming from the topological sector of the underlying theory. We show that a future 100 TeV proton-proton collider (FCC-pp) will be able to test...
Adimensional theory of shielding in ultracold collisions of dipolar rotors
González-Martínez, Maykel L.; Bohn, John L.; Quéméner, Goulven
2017-09-01
We investigate the electric field shielding of ultracold collisions of dipolar rotors, initially in their first rotational excited state, using an adimensional approach. We establish a map of good and bad candidates for efficient evaporative cooling based on this shielding mechanism, by presenting the ratio of elastic over quenching processes as a function of a rescaled rotational constant B ˜=B /sE3 and a rescaled electric field F ˜=d F /B . B ,d ,F ,andsE 3 are respectively the rotational constant, the full electric dipole moment of the molecules, the applied electric field, and a characteristic dipole-dipole energy. We identify two groups of bi-alkali-metal dipolar molecules. The first group, including RbCs, NaK, KCs, LiK, NaRb, LiRb, NaCs, and LiCs, is favorable with a ratio over 1000 at collision energies equal to (or even higher than) their characteristic dipolar energy. The second group, including LiNa and KRb, is not favorable. More generally, for molecules well described by Hund's case b, our adimensional study provides the conditions of efficient evaporative cooling. The range of appropriate rescaled rotational constant and rescaled field is approximately B ˜≥108 and 3.25 ≤F ˜≤3.8 , with a maximum ratio reached for F ˜≃3.4 for a given B ˜. We also discuss the importance of the electronic van der Waals interaction on the adimensional character of our study.
Nonlinear localized modes in dipolar Bose–Einstein condensates in two-dimensional optical lattices
Energy Technology Data Exchange (ETDEWEB)
Rojas-Rojas, Santiago, E-mail: srojas@cefop.cl [Center for Optics and Photonics and MSI-Nucleus on Advanced Optics, Universidad de Concepción, Casilla 160-C, Concepción (Chile); Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción (Chile); Naether, Uta [Instituto de Ciencia de Materiales de Aragón and Departamento de Física de la Materia Condensada, CSIC-Universidad de Zaragoza, 50009 Zaragoza (Spain); Delgado, Aldo [Center for Optics and Photonics and MSI-Nucleus on Advanced Optics, Universidad de Concepción, Casilla 160-C, Concepción (Chile); Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción (Chile); Vicencio, Rodrigo A. [Center for Optics and Photonics and MSI-Nucleus on Advanced Optics, Universidad de Concepción, Casilla 160-C, Concepción (Chile); Departamento de Física, Facultad de Ciencias, Universidad de Chile, Santiago (Chile)
2016-09-16
Highlights: • We study discrete two-dimensional breathers in dipolar Bose–Einstein Condensates. • Important differences in the properties of three fundamental modes are found. • Norm threshold for existence of 2D breathers varies with dipolar interaction. • The Effective Potential Method is implemented for stability analysis. • Uncommon mobility of 2D discrete solitons is observed. - Abstract: We analyze the existence and properties of discrete localized excitations in a Bose–Einstein condensate loaded into a periodic two-dimensional optical lattice, when a dipolar interaction between atoms is present. The dependence of the Number of Atoms (Norm) on the energy of solutions is studied, along with their stability. Two important features of the system are shown, namely, the absence of the Norm threshold required for localized solutions to exist in finite 2D systems, and the existence of regions in the parameter space where two fundamental solutions are simultaneously unstable. This feature enables mobility of localized solutions, which is an uncommon feature in 2D discrete nonlinear systems. With attractive dipolar interaction, a non-trivial behavior of the Norm dependence is obtained, which is well described by an analytical model.
Scale-up of Λ3 : Massive gravity with a higher strong interaction scale
Gabadadze, Gregory
2017-10-01
Pure massive gravity is strongly coupled at a certain low scale, known as Λ3. I show that the theory can be embedded into another one, with new light degrees of freedom, to increase the strong scale to a significantly larger value. Certain universal aspects of the proposed mechanism are discussed, notably that the coupling of the longitudinal mode to a stress tensor is suppressed, thus making the linear theory consistent with the fifth-force exclusion. An example of the embedding theory studied in detail is five-dimensional anti-de Sitter massive gravity, with a large cosmological constant. In this example, the four-dimensional (4D) strong scale can be increased by 19 orders of magnitude. Holographic duality then suggests that the strong scale of the 4D massive gravity can be increased by coupling it to a 4D nonlocal conformal field theory, endowed with a UV cutoff; however, the five-dimensional classical gravity picture appears to be more tractable.
Veljković, Dušan Ž
2018-03-01
Energies of CH/O interactions between water molecule and polycyclic aromatic hydrocarbons with a different number of aromatic rings were calculated using ab initio calculations at MP2/cc-PVTZ level. Results show that an additional aromatic ring in structure of polycyclic aromatic hydrocarbons significantly strengthens CH/O interactions. Calculated interaction energies in optimized structures of the most stable tetracene/water complex is -2.27 kcal/mol, anthracene/water is -2.13 kcal/mol and naphthalene/water is -1.97 kcal/mol. These interactions are stronger than CH/O contacts in benzene/water complex (-1.44 kcal/mol) while CH/O contacts in tetracene/water complex are even stronger than CH/O contacts in pyridine/water complexes (-2.21 kcal/mol). Electrostatic potential maps for different polycyclic aromatic hydrocarbons were calculated and used to explain trends in the energies of interactions. Copyright © 2017 Elsevier Inc. All rights reserved.
Metal-insulator transition in SrIrO3 with strong spin-orbit interaction.
Wu, Fei-Xiang; Zhou, Jian; Zhang, L Y; Chen, Y B; Zhang, Shan-Tao; Gu, Zheng-Bin; Yao, Shu-Hua; Chen, Yan-Feng
2013-03-27
The thickness-dependent metal-insulator transition is observed in meta-stable orthorhombic SrIrO3 thin films synthesized by pulsed laser deposition. SrIrO3 films with thicknesses less than 3 nm demonstrate insulating behaviour, whereas those thicker than 4 nm exhibit metallic conductivity at high temperature, and insulating-like behaviour at low temperature. Weak/Anderson localization is mainly responsible for the observed thickness-dependent metal-insulator transition in SrIrO3 films. Temperature-dependent resistance fitting shows that electrical-conductivity carriers are mainly scattered by the electron-boson interaction rather than the electron-electron interaction. Analysis of the magneto-conductance proves that the spin-orbit interaction plays a crucial role in the magneto-conductance property of SrIrO3.
Strongly interacting vector bosons at the CERN LHC Quartic anomalous couplings
Belyaev, A; González-Garciá, M Concepción; Mizukoshi, J K; Novaes, S F; Zacharov, I E
1999-01-01
We analyze the potential of the CERN Large Hadron Collider to study anomalous quartic vector--boson interactions through the production of vector--boson pairs accompanied by jets. In the framework of $SU(2)_L \\otimes U(1)_Y$ chiral Lagrangians, we examine all effective operators of order $p^4$ that lead to new four--gauge--boson interactions but do not alter trilinear vertices. In our analyses, we perform the full tree level calculation of the processes leading to two jets plus vector--boson pairs, $W^+W^-$, $W^\\pm W^\\pm$, $W^\\pm Z$, or $ZZ$, taking properly into account the interference between the standard model and the anomalous contributions. We obtain the bounds that can be placed on the anomalous quartic interactions and we study the strategies to distinguish the possible new couplings.
A model-independent description of few-body system with strong interaction
International Nuclear Information System (INIS)
Simenog, I.V.
1985-01-01
In this contribution, the authors discuss the formulation of equations that provide model-independent description of systems of three and more nucleons irrespective of the details of the interaction, substantiate the approach, estimate the correction terms with respect to the force range, and give basic qualitative results obtained by means of the model-independent procedure. They consider three nucleons in the doublet state (spin S=I/2) taking into account only S-interaction. The elastic nd-scattering amplitude may be found from the model-independent equations that follow from the Faddeev equations in the short-range-force limit. They note that the solutions of several model-independent equations and basic results obtained with the use of this approach may serve both as a standard solution and starting point in the discussion of various conceptions concerning the details of nuclear interactions
The strong interaction at the collider and cosmic-rays frontiers
d'Enterria, David; Pierog, Tanguy; Ostapchenko, Sergey; Werner, Klaus
2012-01-01
First data on inclusive particle production measured in proton-proton collisions at the Large Hadron Collider (LHC) are compared to predictions of various hadron-interaction Monte Carlos (QGSJET, EPOS and SIBYLL) used commonly in high-energy cosmic-ray physics. While reasonable overall agreement is found for some of the models, none of them reproduces consistently the sqrt(s) evolution of all the measured observables. We discuss the implications of the new LHC data for the modeling of the non-perturbative and semihard parton dynamics in hadron-hadron and cosmic-rays interactions at the highest energies studied today.
Karakostas, Vassilios; Papadimitriou, Eleftheria; Jin, Xueshen; Liu, Zhihui; Paradisopoulou, Parthena; He, Zhang
2013-10-01
Northeast China, a densely populated area, is affected by intense seismic activity, which includes large events that caused extensive disaster and tremendous loss of life. For contributing to the continuous efforts for seismic hazard assessment, the earthquake potential from the active faults near the cities of Zhangjiakou and Langfang in Hebei Province is examined. We estimate the effect of the coseismic stress changes of strong (M ⩾ 5.0) earthquakes on the major regional active faults, and mapped Coulomb stress change onto these target faults. More importantly our calculations reveal that positive stress changes caused by the largest events of the 1976 Tangshan sequence make the Xiadian and part of Daxing fault, thus considered the most likely sites of the next strong earthquake in the study area. The accumulated static stress changes that reached a value of up to 0.4 bar onto these faults, were subsequently incorporated in earthquake probability estimates for the next 30 years.
Spectral asymptotics of a strong delta ' interaction on a planar loop
Czech Academy of Sciences Publication Activity Database
Exner, Pavel; Jex, M.
2013-01-01
Roč. 46, č. 34 (2013), s. 345201 ISSN 1751-8113 R&D Projects: GA ČR GAP203/11/0701 Institutional support: RVO:61389005 Keywords : Schrodinger operators * strong coupling asymptotics Subject RIV: BE - Theoretical Physics Impact factor: 1.687, year: 2013 http://iopscience.iop.org/1751-8121/46/34/345201/pdf/1751-8121_46_34_345201.pdf
Maria J. Lombardero; Matthew P. Ayres; Richard W. Hofstetter; John C. Moser; Kier D. Lepzig
2003-01-01
Phoretic mites of bark beetles are classic examples of commensal ectosymbionts. However, many such mites appear to have mutualisms with fungi that could themselves interact with beetles. We tested for indirect effects of phoretic mites on Dendroctonus frontalis, which auacks and kills pine trees in North America. Tarsonemus mites...
Numerical investigation into strong axis bending shear interaction in rolled I-shaped steel sections
Dekker, R.W.A.; Snijder, B.H.; Maljaars, J.
2016-01-01
Clause 6.2.8 of EN 1993-1-1 covers the design rules on bending-shear resistance, taking presence of shear into account by a reduced yield stress for the shear area. Numerical research on bending-shear interaction by means of the Abaqus Finite Element modelling soft-ware is presented. The numerical
Wu, Ning; Feist, Johannes; Garcia-Vidal, Francisco J.
2016-11-01
We present a microscopic semianalytical theory for the description of organic molecules interacting strongly with a cavity mode. Exciton-vibration coupling within the molecule and exciton-cavity interaction are treated on an equal footing by employing a temperature-dependent variational approach. The interplay between strong exciton-vibration coupling and strong exciton-cavity coupling gives rise to a hybrid ground state, which we refer to as the lower polaron polariton. Explicit expressions for the ground-state wave function, the zero-temperature quasiparticle weight of the lower polaron polariton, the photoluminescence line strength, and the mean number of vibrational quanta are obtained in terms of the optimal variational parameters. The dependence of these quantities upon the exciton-cavity coupling strength reveals that strong cavity coupling leads to an enhanced vibrational dressing of the cavity mode, and at the same time a vibrational decoupling of the dark excitons, which in turn results in a lower polaron polariton resembling a single-mode dressed bare lower polariton in the strong-coupling regime. Thermal effects on several observables are briefly discussed.
International Nuclear Information System (INIS)
Biebel, O.
1993-11-01
A study of possible flavour dependence of the strong interaction is presented using data collected with the OPAL detector at the e + e - collider LEP. Four subsamples of events, highly enriched in bottom, charm, strange and light quarks are obtained from high momentum electrons and muons, D *± mesons, K s 0 mesons, and highly energetic stable charged particles, respectively. From the jet production rates of each of these four samples a strong coupling constant α s f for the dominant quark flavour is derived. The ratios of α s for a specific quark flavour f and its complementary flavours are determined to be α s b /α s udsc =1.017±0.036, α s c /α s udsb =0.918±0.115, α s s /α s udcb =1.158±0.164, α s uds /α s cb =1.038 ± 0.221, where the errors are combinations of statistical and systematic uncertainties. In combining the relevant data samples, a systematic study of possible dependence of the strong interaction on quark mass, weak isospin, and generation is performed. No evidence for any such dependence of the strong coupling constant α s is observed. Finally all samples are combined to determine the strong coupling constant of each flavour individually. Again the results are well consistent with the flavour independence of QCD. (orig.)
Strong electron-phonon interaction in the high-Tc superconductors: Evidence from the infrared
International Nuclear Information System (INIS)
Timusk, T.; Porter, C.D.; Tanner, D.B.
1991-01-01
We show that low-frequency structure in the infrared reflectance of the high-temperature superconductor YBa 2 Cu 3 O 7 results from the electron-phonon interaction. Characteristic antiresonant line shapes are seen in the phonon region of the spectrum and the frequency-dependent scattering rate of the mid-infrared electronic continuum has peaks at 150 cm -1 (19 meV) and at 360 cm -1 (45 meV) in good agreement with phonon density-of-states peaks in neutron time-of-flight spectra that develop in superconducting samples. The interaction between the phonons and the charge carriers can be understood in terms of a charged-phonon model
Application of the CIP Method to Strongly Nonlinear Wave-Body Interaction Problems
Zhu, Xinying
2006-01-01
Water entry and exit, green water on deck, sloshing in tanks and capsizing in intact and damaged conditions are examples on violent fluid motion. The combination of model tests, theoretical analysis and Computational Fluid Dynamics (CFD) methods is emphasized in treating these problems. Because mixing of air and liquid may occur, the interaction between the flow in the air and in the liquid ought to be considered in numerical simulations. Further, the mixing of air and liquid represents a sca...
On the starting process of strongly nonlinear vortex/Rayleigh-wave interactions
BROWN, P. G.; BROWN, S. N.; SMITH, F. T.; TIMOSHIN, S. N.
1993-01-01
An oncoming two-dimensional laminar boundary layer that develops an unstable inflection point and becomes three-dimensional is described by the Hall-Smith (1991) vortex/wave interaction equations. These equations are now examined in the neighbourhood of the position where the critical surface starts to form. A consistent structure is established in which an inviscid core flow is matched to a viscous buffer-layer solution where the appropriate jump condition on the transverse shear stress is s...
Second sound in a two-dimensional Bose gas: From the weakly to the strongly interacting regime
Ota, Miki; Stringari, Sandro
2018-03-01
Using Landau's theory of two-fluid hydrodynamics, we investigate first and second sounds propagating in a two-dimensional (2D) Bose gas. We study the temperature and interaction dependence of both sound modes and show that their behavior exhibits a deep qualitative change as the gas evolves from the weakly interacting to the strongly interacting regime. Special emphasis is placed on the jump of both sounds at the Berezinskii-Kosterlitz-Thouless transition, caused by the discontinuity of the superfluid density. We find that the excitation of second sound through a density perturbation becomes weaker and weaker as the interaction strength increases as a consequence of the decrease in the thermal expansion coefficient. Our results could be relevant for future experiments on the propagation of sound on the Bose-Einstein condensate (BEC) side of the BCS-BEC crossover of a 2D superfluid Fermi gas.
Bertini, Lorenzo; Cirillo, Emilio N. M.; Olivieri, Enzo
1999-12-01
In this paper we study a renormalization-group map: the block averaging transformation applied to Gibbs measures relative to a class of finite-range lattice gases, when suitable strong mixing conditions are satisfied. Using a block decimation procedure, cluster expansion, and detailed comparison between statistical ensembles, we are able to prove Gibbsianness and convergence to a trivial (i.e., Gaussian and product) fixed point. Our results apply to the 2D standard Ising model at any temperature above the critical one and arbitrary magnetic field.
CLEO-c and CESR-c: A new frontier in strong and weak interactions
Energy Technology Data Exchange (ETDEWEB)
Richichi, Stephen J
2003-06-01
We report on the physics potential of a charm and QCD factory, based on a proposal for the conversion of the existing CESR machine and CLEO detector: ''CESR-c and OLEO-c''. Such a facility will make major contributions to the field of quark flavor physics in this decade. It may also provide the best chance for understanding non-perturbative QCD, which is essential to understanding the strongly-coupled sectors of the new physics that lies beyond the Standard Model.
CLEO-c and CESR-c: A new frontier in strong and weak interactions
Richichi, Stephen J.
2003-06-01
We report on the physics potential of a charm and QCD factory, based on a proposal for the conversion of the existing CESR machine and CLEO detector: "CESR-c and OLEO-c". Such a facility will make major contributions to the field of quark flavor physics in this decade. It may also provide the best chance for understanding non-perturbative QCD, which is essential to understanding the strongly-coupled sectors of the new physics that lies beyond the Standard Model.
CLEO-c and CESR-c: A new frontier in strong and weak interactions
International Nuclear Information System (INIS)
Richichi, Stephen J.
2003-01-01
We report on the physics potential of a charm and QCD factory, based on a proposal for the conversion of the existing CESR machine and CLEO detector: ''CESR-c and OLEO-c''. Such a facility will make major contributions to the field of quark flavor physics in this decade. It may also provide the best chance for understanding non-perturbative QCD, which is essential to understanding the strongly-coupled sectors of the new physics that lies beyond the Standard Model
Energy Technology Data Exchange (ETDEWEB)
Quinn, John
2009-11-30
Work related to this project introduced the idea of an effective monopole strength Q* that acted as the effective angular momentum of the lowest shell of composite Fermions (CF). This allowed us to predict the angular momentum of the lowest band of energy states for any value of the applied magnetic field simply by determining N{sub QP} the number of quasielectrons (QE) or quasiholes (QH) in a partially filled CF shell and adding angular momenta of the N{sub QP} Fermions excitations. The approach reported treated the filled CF level as a vacuum state which could support QE and QH excitations. Numerical diagonalization of small systems allowed us to determine the angular momenta, the energy, and the pair interaction energies of these elementary excitations. The spectra of low energy states could then be evaluated in a Fermi liquid-like picture, treating the much smaller number of quasiparticles and their interactions instead of the larger system of N electrons with Coulomb interactions.
Strong electromagnetic pulses generated in high-intensity laser-matter interactions
Rączka, P.; Dubois, J.-L.; Hulin, S.; Rosiński, M.; Zaraś-Szydłowska, A.; Badziak, J.
2018-01-01
Results are reported of an experiment performed at the Eclipse laser facility in CELIA, Bordeaux, on the generation of strong electromagnetic pulses. Measurements were performed of the target neutralization current, the total target charge and the tangential component of the magnetic field for the laser energies ranging from 45 mJ to 92 mJ with the pulse duration approximately 40 fs, and for the pulse durations ranging from 39 fs to 1000 fs, with the laser energy approximately 90 mJ. It was found that the values obtained for thick (mm scale) Cu targets are visibly higher than values reported in previous experiments, which is argued to be a manifestation of a strong dependence of the target electric polarization process on the laser contrast and hence on the amount of preplasma. It was also found that values obtained for thin (μm scale) Al foils were visibly higher than values for thick Cu targets, especially for pulse durations longer than 100 fs. The correlations between the total target charge versus the maximum value of the target neutralization current, and the maximum value of the tangential component of the magnetic field versus the total target charge were analysed. They were found to be in very good agreement with correlations seen in data from previous experiments, which provides a good consistency check on our experimental procedures.
Metastability and avalanche dynamics in strongly correlated gases with long-range interactions
Hruby, Lorenz; Dogra, Nishant; Landini, Manuele; Donner, Tobias; Esslinger, Tilman
2018-03-01
We experimentally study the stability of a bosonic Mott insulator against the formation of a density wave induced by long-range interactions and characterize the intrinsic dynamics between these two states. The Mott insulator is created in a quantum degenerate gas of 87-Rubidium atoms, trapped in a 3D optical lattice. The gas is located inside and globally coupled to an optical cavity. This causes interactions of global range, mediated by photons dispersively scattered between a transverse lattice and the cavity. The scattering comes with an atomic density modulation, which is measured by the photon flux leaking from the cavity. We initialize the system in a Mott-insulating state and then rapidly increase the global coupling strength. We observe that the system falls into either of two distinct final states. One is characterized by a low photon flux, signaling a Mott insulator, and the other is characterized by a high photon flux, which we associate with a density wave. Ramping the global coupling slowly, we observe a hysteresis loop between the two states—a further signature of metastability. A comparison with a theoretical model confirms that the metastability originates in the competition between short- and global-range interactions. From the increasing photon flux monitored during the switching process, we find that several thousand atoms tunnel to a neighboring site on the timescale of the single-particle dynamics. We argue that a density modulation, initially forming in the compressible surface of the trapped gas, triggers an avalanche tunneling process in the Mott-insulating region.
Relaxation of strongly coupled Coulomb systems after rapid changes of the interaction potential
Gericke, D O; Semkat, D; Bonitz, M; Kremp, D
2003-01-01
The relaxation of charged particle systems after sudden changes of the pair interaction strength is investigated. As examples, we show the results for plasmas after ionization and after a rapid change of screening. Comparisons are made between molecular dynamics simulation and a kinetic description based on the Kadanoff-Baym equations. We found the latter very sensitive to the way the scattering cross section is treated. We also predict the new equilibrium state requiring only conservation of energy. In this case, the correlation energy is computed using the hypernetted chain approximation.
Energy Technology Data Exchange (ETDEWEB)
Daily, Michael D.; Baer, Marcel D.; Mundy, Christopher J.
2016-03-10
The description of peptides and the use of molecular dynamics simulations to refine structures and investigate the dynamics on an atomistic scale are well developed. Through a consensus in this community over multiple decades, parameters were developed for molecular interactions that only require the sequence of amino-acids and an initial guess for the three-dimensional structure. The recent discovery of peptoids will require a retooling of the currently available interaction potentials in order to have the same level of confidence in the predicted structures and pathways as there is presently in the peptide counterparts. Here we present modeling of peptoids using a combination of ab initio molecular dynamics (AIMD) and atomistic resolution classical forcefield (FF) to span the relevant time and length scales. To properly account for the dominant forces that stabilize ordered structures of peptoids, namely steric-, electrostatic, and hydrophobic interactions mediated through sidechain-sidechain interactions in the FF model, those have to be first mapped out using high fidelity atomistic representations. A key feature here is not only to use gas phase quantum chemistry tools, but also account for solvation effects in the condensed phase through AIMD. One major challenge is to elucidate ion binding to charged or polar regions of the peptoid and its concomitant role in the creation of local order. Here, similar to proteins, a specific ion effect is observed suggesting that both the net charge and the precise chemical nature of the ion will need to be described. MDD was supported by MS3 (Materials Synthesis and Simulation Across Scales) Initiative at Pacific Northwest National Laboratory. Research was funded by the Laboratory Directed Research and Development program at Pacific Northwest National Laboratory. MDB acknowledges support from US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Material & Engineering. CJM acknowledges
International Nuclear Information System (INIS)
Yu Zengqiang; Zhai Hui; Zhang Shizhong
2011-01-01
We study the properties of dilute bosons immersed in a single-component Fermi sea across a broad boson-fermion Feshbach resonance. The stability of the mixture requires that the bare interaction between bosons exceeds a critical value, which is a universal function of the boson-fermion scattering length, and exhibits a maximum in the unitary region. We calculate the quantum depletion, momentum distribution, and the boson contact parameter across the resonance. The transition from condensate to molecular Fermi gas is also discussed.
Energy Technology Data Exchange (ETDEWEB)
Schriber, Jeffrey B.; Evangelista, Francesco A. [Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322 (United States)
2016-04-28
We introduce a new procedure for iterative selection of determinant spaces capable of describing highly correlated systems. This adaptive configuration interaction (ACI) determines an optimal basis by an iterative procedure in which the determinant space is expanded and coarse grained until self-consistency. Two importance criteria control the selection process and tune the ACI to a user-defined level of accuracy. The ACI is shown to yield potential energy curves of N{sub 2} with nearly constant errors, and it predicts singlet-triplet splittings of acenes up to decacene that are in good agreement with the density matrix renormalization group.
Wan, Sijie; Peng, Jingsong; Li, Yuchen; Hu, Han; Jiang, Lei; Cheng, Qunfeng
2015-10-27
Graphene is the strongest and stiffest material, leading to the development of promising applications in many fields. However, the assembly of graphene nanosheets into macrosized nanocomposites for practical applications remains a challenge. Nacre in its natural form sets the "gold standard" for toughness and strength, which serves as a guide to the assembly of graphene nanosheets into high-performance nanocomposites. Here we show the strong, tough, conductive artificial nacre based on graphene oxide through synergistic interactions of hydrogen and covalent bonding. Tensile strength and toughness was 4 and 10 times higher, respectively, than that of natural nacre. The exceptional integrated strong and tough artificial nacre has promising applications in aerospace, artificial muscle, and tissue engineering, especially for flexible supercapacitor electrodes due to its high electrical conductivity. The use of synergistic interactions is a strategy for the development of high-performance nanocomposites.
Directory of Open Access Journals (Sweden)
Hanna Björkelund
Full Text Available The interaction of the epidermal growth factor (EGF with its receptor (EGFR is known to be complex, and the common over-expression of EGF receptor family members in a multitude of tumors makes it important to decipher this interaction and the following signaling pathways. We have investigated the affinity and kinetics of (125I-EGF binding to EGFR in four human tumor cell lines, each using four culturing conditions, in real time by use of LigandTracer®.Highly repeatable and precise measurements show that the overall apparent affinity of the (125I-EGF - EGFR interaction is greatly dependent on cell line at normal culturing conditions, ranging from K(D ≈ 200 pM on SKBR3 cells to K(D≈8 nM on A431 cells. The (125I-EGF - EGFR binding curves (irrespective of cell line have strong signs of multiple simultaneous interactions. Furthermore, for the cell lines A431 and SKOV3, gefitinib treatment increases the (125I-EGF - EGFR affinity, in particular when the cells are starved. The (125I-EGF - EGFR interaction on cell line U343 is sensitive to starvation while as on SKBR3 it is insensitive to gefitinib and starvation.The intriguing pattern of the binding characteristics proves that the cellular context is important when deciphering how EGF interacts with EGFR. From a general perspective, care is advisable when generalizing ligand-receptor interaction results across multiple cell-lines.
Equilibration of a strongly interacting plasma: holographic analysis of local and nonlocal probes
Directory of Open Access Journals (Sweden)
Bellantuono Loredana
2016-01-01
Full Text Available The relaxation of a strongly coupled plasma towards the hydrodynamic regime is studied by analyzing the evolution of local and nonlocal observables in the holographic approach. The system is driven in an initial anisotropic and far-from equilibrium state through an impulsive time-dependent deformation (quench of the boundary spacetime geometry. Effective temperature and entropy density are related to the position and area of a black hole horizon, which has formed as a consequence of the distortion. The behavior of stress-energy tensor, equal-time correlation functions and Wilson loops of different shapes is examined, and a hierarchy among their thermalization times emerges: probes involving shorter length scales thermalize faster.
Nonlinear interaction of charged particles with strong laser pulses in a gaseous media
Directory of Open Access Journals (Sweden)
H. K. Avetissian
2007-07-01
Full Text Available The charged particles nonlinear dynamics in the field of a strong electromagnetic wave pulse of finite duration and certain form of the envelope, in the refractive medium with a constant and variable refraction indexes, is investigated by means of numerical integration of the classical relativistic equations of motion. The particle energy dependence on the pulse intensity manifests the nonlinear threshold phenomenon of a particle reflection and capture by actual laser pulses in dielectric-gaseous media that takes place for a plane electromagnetic wave in the induced Cherenkov process. Laser acceleration of the particles in the result of the reflection from the pulse envelope and in the capture regime with the variable refraction index along the pulse propagation direction is investigated.
Strongly coupled interaction between a ridge of fluid and an inviscid airflow
Paterson, C.
2015-07-01
© 2015 AIP Publishing LLC. The behaviour of a steady thin sessile or pendent ridge of fluid on an inclined planar substrate which is strongly coupled to the external pressure gradient arising from an inviscid airflow parallel to the substrate far from the ridge is described. When the substrate is nearly horizontal, a very wide ridge can be supported against gravity by capillary and/or external pressure forces; otherwise, only a narrower (but still wide) ridge can be supported. Classical thin-aerofoil theory is adapted to obtain the governing singular integro-differential equation for the profile of the ridge in each case. Attention is focused mainly on the case of a very wide sessile ridge. The effect of strengthening the airflow is to push a pinned ridge down near to its edges and to pull it up near to its middle. At a critical airflow strength, the upslope contact angle reaches the receding contact angle at which the upslope contact line de-pins, and continuing to increase the airflow strength beyond this critical value results in the de-pinned ridge becoming narrower, thicker, and closer to being symmetric in the limit of a strong airflow. The effect of tilting the substrate is to skew a pinned ridge in the downslope direction. Depending on the values of the advancing and receding contact angles, the ridge may first de-pin at either the upslope or the downslope contact line but, in general, eventually both contact lines de-pin. The special cases in which only one of the contact lines de-pins are also considered. It is also shown that the behaviour of a very wide pendent ridge is qualitatively similar to that of a very wide sessile ridge, while the important qualitative difference between the behaviour of a very wide ridge and a narrower ridge is that, in general, for the latter one or both of the contact lines may never de-pin.
Strong interaction between graphene layer and Fano resonance in terahertz metamaterials
Xiao, Shuyuan; Wang, Tao; Jiang, Xiaoyun; Yan, Xicheng; Cheng, Le; Wang, Boyun; Xu, Chen
2017-05-01
Graphene has emerged as a promising building block in modern optics and optoelectronics due to its novel optical and electrical properties. In the mid-infrared and terahertz (THz) regime, graphene behaves like metals and supports surface plasmon resonances (SPRs). Moreover, the continuously tunable conductivity of graphene enables active SPRs and gives rise to a range of active applications. However, the interaction between graphene and metal-based resonant metamaterials has not been fully understood. In this work, a simulation investigation on the interaction between the graphene layer and THz resonances supported by the two-gap split ring metamaterials is systematically conducted. The simulation results show that the graphene layer can substantially reduce the Fano resonance and even switch it off, while leaving the dipole resonance nearly unaffected, which is well explained with the high conductivity of graphene. With the manipulation of graphene conductivity via altering its Fermi energy or layer number, the amplitude of the Fano resonance can be modulated. The tunable Fano resonance here together with the underlying physical mechanism can be strategically important in designing active metal-graphene hybrid metamaterials. In addition, the ‘sensitivity’ to the graphene layer of the Fano resonance is also highly appreciated in the field of ultrasensitive sensing, where the novel physical mechanism can be employed in sensing other graphene-like two-dimensional materials or biomolecules with the high conductivity.
DEFF Research Database (Denmark)
Loft, N. J. S.; Marchukov, O. V.; Petrosyan, D.
2016-01-01
We have developed an efficient computational method to treat long, one-dimensional systems of strongly-interacting atoms forming self-assembled spin chains. Such systems can be used to realize many spin chain model Hamiltonians tunable by the external confining potential. As a concrete...... demonstration, we consider quantum state transfer in a Heisenberg spin chain and we show how to determine the confining potential in order to obtain nearly-perfect state transfer....
Strong electromagnetic pulses generated in laser-matter interactions with 10TW-class fs laser
Rączka, Piotr; Rosiński, Marcin; Zaraś-Szydłowska, Agnieszka; Wołowski, Jerzy; Badziak, Jan
2018-01-01
The results of an experiment on the generation of electromagnetic pulses (EMP) in the interaction of 10TW fs pulses with thick (mm scale) and thin foil (μm scale) targets are described. Such pulses, with frequencies in the GHz range, may pose a threat to safe and reliable operation of high-power, high-intensity laser facilities. The main point of the experiment is to investigate the fine temporal structure of such pulses using an oscilloscope capable of measurements at very high sampling rate. It is found that the amazing reproducibility of such pulses is confirmed at this high sampling rate. Furthermore, the differences between the EMP signals generated from thick and thin foil targets are clearly seen, which indicates that besides electric polarization of the target and the target neutralization current there may be other factors essential for the EMP emission.
Radio and X-Ray Observations of SN 2006jd: Another Strongly Interacting Type IIn Supernova
Chandra, Poonam; Chevalier, Roger A.; Chugai, Nikolai; Fransson, Claes; Irwin, Christopher M.; Soderberg, Alicia M.; Chakraborti, Sayan; Immler, Stefan
2012-01-01
We report four years of radio and X-ray monitoring of the Type IIn supernova SN 2006jd at radio wavelengths with the Very Large Array, Giant Metrewave Radio Telescope and Expanded Very Large Array at X-ray wavelengths with Chandra, XMM-Newton and Swift-XRT. We assume that the radio and X-ray emitting particles are produced by shock interaction with a dense circumstellar medium. The radio emission shows an initial rise that can be attributed to free-free absorption by cool gas mixed into the nonthermal emitting region external free-free absorption is disfavored because of the shape of the rising light curves and the low gas column density inferred along the line of sight to the emission region. The X-ray luminosity implies a preshock circumstellar density approximately 10(exp 6) per cubic meter at a radius r approximately 2 x 10(exp 16) centimeter, but the column density inferred from the photoabsorption of X-rays along the line of sight suggests a significantly lower density. The implication may be an asymmetry in the interaction. The X-ray spectrum shows Fe line emission at 6.9 keV that is stronger than is expected for the conditions in the X-ray emitting gas. We suggest that cool gas mixed into the hot gas plays a role in the line emission. Our radio and X-ray data both suggest the density profile is flatter than r2 because of the slow evolution of the unabsorbed emission.
DEFF Research Database (Denmark)
Jochumsen, Nicholas; Marvig, Rasmus Lykke; Pedersen, Søren Damkiær
2016-01-01
Colistin is an antimicrobial peptide that has become the only remaining alternative for the treatment of multidrug-resistant Gram-negative bacterial infections, but little is known of how clinical levels of colistin resistance evolve. We use in vitro experimental evolution and whole-genome sequen......Colistin is an antimicrobial peptide that has become the only remaining alternative for the treatment of multidrug-resistant Gram-negative bacterial infections, but little is known of how clinical levels of colistin resistance evolve. We use in vitro experimental evolution and whole......-genome sequencing of colistin-resistant Pseudomonas aeruginosa isolates from cystic fibrosis patients to reconstruct the molecular evolutionary pathways open for high-level colistin resistance. We show that the evolution of resistance is a complex, multistep process that requires mutation in at least five...... independent loci that synergistically create the phenotype. Strong intergenic epistasis limits the number of possible evolutionary pathways to resistance. Mutations in transcriptional regulators are essential for resistance evolution and function as nodes that potentiate further evolution towards higher...
Voltage-Controlled Switching of Strong Light-Matter Interactions using Liquid Crystals.
Hertzog, Manuel; Rudquist, Per; Hutchison, James A; George, Jino; Ebbesen, Thomas W; Börjesson, Karl
2017-12-22
We experimentally demonstrate a fine control over the coupling strength of vibrational light-matter hybrid states by controlling the orientation of a nematic liquid crystal. Through an external voltage, the liquid crystal is seamlessly switched between two orthogonal directions. Using these features, for the first time, we demonstrate electrical switching and increased Rabi splitting through transition dipole moment alignment. The C-N str vibration on the liquid crystal molecule is coupled to a cavity mode, and FT-IR is used to probe the formed vibropolaritonic states. A switching ratio of the Rabi splitting of 1.78 is demonstrated between the parallel and the perpendicular orientation. Furthermore, the orientational order increases the Rabi splitting by 41 % as compared to an isotropic liquid. Finally, by examining the influence of molecular alignment on the Rabi splitting, the scalar product used in theoretical modeling between light and matter in the strong coupling regime is verified. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Inelastic strong interactions at high energies. Annual progress report, June 1, 1979-May 1, 1980
International Nuclear Information System (INIS)
Suranyi, P.
1980-02-01
Investigations in the area of Grand Unified Field Theories were begun. Various ways of breaking the SU(5) symmetric theory of Georgi and Glashow were studied. As usual, an approx. 24 of Higgs breaks the symmetry from SU(5) to SU(3)/sub c/xSU(2)xU(1). It was found that an approx. 45 of Higgs is acceptable for breaking the symmetry from SU(3)/sub c/xSU(2)xU(1) to SU(3)/sub c/xU(1)/sub em/. In addition phenomenologically correct quark-lepton mass ratios are obtained by use of renormalization-group techniques if there are 6 generations of particles in the theory. Efforts directed at the development of approximate methods for extracting information from quantum field theories were continued. The quantum mechanics of polynomial potentials as a model for quantum field theories was investigated. A perturbation expansion for the energy levels and wave functions was constructed and has been proven to be convergent for arbitrary values of the coupling constants, in contrast to ordinary perturbation expansions that have a zero radius of convergence. The physical significance of the new perturbation expansions was explored both in the weak and strong coupling limits
Particle-in-cell Simulation of Dipolarization Front Associated Whistlers
Lin, D.; Scales, W.; Ganguli, G.; Crabtree, C. E.
2017-12-01
Dipolarization fronts (DFs) are dipolarized magnetic field embedded in the Earthward propagating bursty bulk flows (BBFs), which separates the hot, tenuous high-speed flow from the cold, dense, and slowly convecting surrounding plasma [Runov et al. 2011]. Broadband fluctuations have been observed at DFs including the electromagnetic whistler waves and electrostatic lower hybrid waves in the Very Low Frequency (VLF) range [e.g., Zhou et al. 2009, Deng et al. 2010]. There waves are suggested to be able heat electrons and play a critical role in the plasma sheet dynamics [Chaston et al., 2012, Angelopoulos et al., 2013]. However, their generation mechanism and role in the energy conversion are still under debate. The gradient scale of magnetic field, plasma density at DFs in the near-Earth magnetotail is comparable to or lower than the ion gyro radius [Runov et al., 2011, Fu et al., 2012, Breuillard et al., 2016]. Such strongly inhomogeneous configuration could be unstable to the electron-ion hybrid (EIH) instability, which arises from strongly sheared transverse flow and is in the VLF range [Ganguli et al. 1988, Ganguli et al. 2014]. The equilibrium of the EIH theory implies an anisotropy of electron temperature, which are likely to drive the whistler waves observed in DFs [Deng et al., 2010, Gary et al., 2011]. In order to better understand how the whistler waves are generated in DFs and whether the EIH theory is applicable, a fully electromagnetic particle-in-cell (EMPIC) model is used to simulate the EIH instability with similar equilibrium configurations in DF observations. The EMPIC model deals with three dimensions in the velocity space and two dimensions in the configuration space, which is quite ready to include the third configuration dimension. Simulation results will be shown in this presentation.
International Nuclear Information System (INIS)
Sherman, A.; Schreiber, M.
1995-01-01
We use the Eliashberg formalism for calculating T c in a model of cuprate perovskites with pairing mediated by both magnons and apex-oxygen vibrations. The influence of strong correlations on the energy spectrum is taken into account in the spin-wave approximation. It is shown that the hole-magnon interaction alone cannot yield high T c . But together with a moderate hole-phonon interaction it does lead to d-wave superconductivity at temperatures and hole concentrations observed in cuprates. High T c are connected with a large density of states due to extended Van Hove singularities, a conformity of the two interactions for the d symmetry, and high phonon frequencies
Powers, Lydia
The National Museum of Play at The Strong's Dancing Wings Butterfly Garden is a tropical rainforest that allows visitors to step into the world of butterflies, but lacks a more comprehensive educational element to teach visitors additional information about butterflies. Flutter-by Interactive Butterfly is a thesis project designed to enhance younger visitors' experience of the Dancing Wings Butterfly Garden with an interactive educational application that aligns with The Strong's mission of encouraging learning, creativity, and discovery. This was accomplished through a series of fun and educational games and animations, designed for use as a kiosk outside the garden and as a part of The Strong's website. Content, planning, and organization of this project has been completed through research and observation of the garden in the following areas: its visitors, butterflies, best usability practices for children, and game elements that educate and engage children. Flutter-by Interactive Butterfly teaches users about the butterfly's life cycle, anatomy, and characteristics as well as their life in the Dancing Wings Butterfly Garden. Through the use of the design programs Adobe Illustrator, Flash, and After Effects; the programming language ActionScript3.0; a child-friendly user interface and design; audio elements and user takeaways, Flutter-by Interactive Butterfly appeals to children of all ages, interests, and learning styles. The project can be viewed at lydiapowers.com/Thesis/FlutterByButterfly.html
Some issues linked to the description of systems in strong interaction
International Nuclear Information System (INIS)
Theussl, L.
2001-06-01
In the first part of this work we have dealt with some issues that are relevant in the area of nucleonic resonances within different constituent quark models. In this context we have concentrated on the theoretical description of Pi and Nu decays for N and Delta resonances. The results obtained point to the necessity of a more microscopic description of the dynamics which is at the same time responsible for the binding of quarks inside baryons and the decay of the latter ones. In the second part we have contributed to the study of crossed two-boson exchanges in the Bethe-Salpeter equation as well as to the investigation of different three-dimensional approaches that follow from the Bethe-Salpeter equation in a certain non-relativistic reduction scheme. These one include in particular an equation whose interaction depends on the total energy of the system. It was shown that such an equation is able to account for a certain number of properties of Bethe-Salpeter equation, in particular, that there also arise abnormal solutions in such an approach. (author)
Liu, Yu; Begin-Colin, Sylvie; Pichon, Benoît P; Leuvrey, Cedric; Ihiawakrim, Dris; Rastei, Mircea; Schmerber, Guy; Vomir, Mircea; Bigot, Jean Yves
2014-10-21
The dimensionality of assembled nanoparticles plays an important role in their optical and magnetic properties, via dipolar effects and the interaction with their environment. In this work we develop a methodology for distinguishing between two (2D) and three (3D) dimensional collective interactions on the surface plasmon resonance of assembled metal nanoparticles. Towards that goal, we elaborate different sets of Au and Ag nanoparticles as suspensions, random 3D arrangements and well organized 2D arrays. Then we model their scattering cross-section using effective field methods in dimension n, including interparticle as well as particle-substrate dipolar interactions. For this modelling, two effective field medium approaches are employed, taking into account the filling factors of the assemblies. Our results are important for realizing photonic amplifier devices.
Layers of Cold Dipolar Molecules in the Harmonic Approximation
DEFF Research Database (Denmark)
R. Armstrong, J.; Zinner, Nikolaj Thomas; V. Fedorov, D.
2012-01-01
We consider the N-body problem in a layered geometry containing cold polar molecules with dipole moments that are polarized perpendicular to the layers. A harmonic approximation is used to simplify the hamiltonian and bound state properties of the two-body inter-layer dipolar potential are used...... to adjust this effective interaction. To model the intra-layer repulsion of the polar molecules, we introduce a repulsive inter-molecule potential that can be parametrically varied. Single chains containing one molecule in each layer, as well as multi-chain structures in many layers are discussed...... and their energies and radii determined. We extract the normal modes of the various systems as measures of their volatility and eventually of instability, and compare our findings to the excitations in crystals. We find modes that can be classified as either chains vibrating in phase or as layers vibrating against...
Hidden magnetism in periodically modulated one dimensional dipolar fermions
Fazzini, S.; Montorsi, A.; Roncaglia, M.; Barbiero, L.
2017-12-01
The experimental realization of time-dependent ultracold lattice systems has paved the way towards the implementation of new Hubbard-like Hamiltonians. We show that in a one-dimensional two-components lattice dipolar Fermi gas the competition between long range repulsion and correlated hopping induced by periodically modulated on-site interaction allows for the formation of hidden magnetic phases, with degenerate protected edge modes. The magnetism, characterized solely by string-like nonlocal order parameters, manifests in the charge and/or in the spin degrees of freedom. Such behavior is enlighten by employing Luttinger liquid theory and numerical methods. The range of parameters for which hidden magnetism is present can be reached by means of the currently available experimental setups and probes.
Strong Hydrogen Bonded Molecular Interactions between Atmospheric Diamines and Sulfuric Acid.
Elm, Jonas; Jen, Coty N; Kurtén, Theo; Vehkamäki, Hanna
2016-05-26
We investigate the molecular interaction between methyl-substituted N,N,N',N'-ethylenediamines, propane-1,3-diamine, butane-1,4-diamine, and sulfuric acid using computational methods. Molecular structure of the diamines and their dimer clusters with sulfuric acid is studied using three density functional theory methods (PW91, M06-2X, and ωB97X-D) with the 6-31++G(d,p) basis set. A high level explicitly correlated CCSD(T)-F12a/VDZ-F12 method is used to obtain accurate binding energies. The reaction Gibbs free energies are evaluated and compared with values for reactions involving ammonia and atmospherically relevant monoamines (methylamine, dimethylamine, and trimethylamine). We find that the complex formation between sulfuric acid and the studied diamines provides similar or more favorable reaction free energies than dimethylamine. Diamines that contain one or more secondary amino groups are found to stabilize sulfuric acid complexes more efficiently. Elongating the carbon backbone from ethylenediamine to propane-1,3-diamine or butane-1,4-diamine further stabilizes the complex formation with sulfuric acid by up to 4.3 kcal/mol. Dimethyl-substituted butane-1,4-diamine yields a staggering formation free energy of -19.1 kcal/mol for the clustering with sulfuric acid, indicating that such diamines could potentially be a key species in the initial step in the formation of new particles. For studying larger clusters consisting of a diamine molecule with up to four sulfuric acid molecules, we benchmark and utilize a domain local pair natural orbital coupled cluster (DLPNO-CCSD(T)) method. We find that a single diamine is capable of efficiently stabilizing sulfuric acid clusters with up to four acid molecules, whereas monoamines such as dimethylamine are capable of stabilizing at most 2-3 sulfuric acid molecules.
Temperature Dependence of the Thermal Conductivity of a Trapped Dipolar Bose-Condensed Gas
Yavari, H.
2018-02-01
The thermal conductivity of a trapped dipolar Bose condensed gas is calculated as a function of temperature in the framework of linear response theory. The contributions of the interactions between condensed and noncondensed atoms and between noncondensed atoms in the presence of both contact and dipole-dipole interactions are taken into account to the thermal relaxation time, by evaluating the self-energies of the system in the Beliaev approximation. We will show that above the Bose-Einstein condensation temperature ( T > T BEC ) in the absence of dipole-dipole interaction, the temperature dependence of the thermal conductivity reduces to that of an ideal Bose gas. In a trapped Bose-condensed gas for temperature interval k B T > k B T, since the relaxation rate {τ}_{c12}^{-1} is independent of temperature and the relaxation rate due to dipolar interaction goes to zero exponentially, the T 2 temperature behavior for the thermal conductivity comes from the thermal mean velocity of the particles. We will also show that in the high-temperature limit ( k B T > n 0 g B ) and low momenta, the relaxation rates {τ}_{c12}^{-1} and {τ}_{dd12}^{-1} change linearly with temperature for both dipolar and contact interactions and the thermal conductivity scales linearly with temperature.
Anisotropic relaxation dynamics in a dipolar Fermi gas driven out of equilibrium
DEFF Research Database (Denmark)
Aikawa, K.; Frisch, A.; Mark, M.
2014-01-01
We report on the observation of a large anisotropy in the rethermalization dynamics of an ultracold dipolar Fermi gas driven out of equilibrium. Our system consists of an ultracold sample of strongly magnetic $^{167}$Er fermions, spin-polarized in the lowest Zeeman sublevel. In this system, elastic...... collisions arise purely from universal dipolar scattering. Based on cross-dimensional rethermalization experiments, we observe a strong anisotropy of the scattering, which manifests itself in a large angular dependence of the thermal relaxation dynamics. Our result is in very good agreement with recent...... theoretical predictions. Furthermore, we measure the rethermalization rate as a function of temperature for different angles and find that the suppression of collisions by Pauli blocking is not influenced by the dipole orientation....
Voskresenskaya, O O
2002-01-01
It is shown that the relations between probabilities of A_{2\\pi}-atoms creation in ns-states, derived with neglecting of strong interaction between pions, hold practically unchanged if the strong interaction is taken into account in the first order of perturbation theory. The formulation of Deser equation for the energy levels shift of the hadronic atoms (HA) is given in terms of effective range of strong interaction and relative correction to the coulombic wave function of HA at origin, caused by strong interaction.
Cirhin up-regulates a canonical NF-{kappa}B element through strong interaction with Cirip/HIVEP1
Energy Technology Data Exchange (ETDEWEB)
Yu, Bin; Mitchell, Grant A. [Genetique Medicale, Centre de Recherche CHU Sainte-Justine, Departement de Pediatrie, Universite de Montreal, Montreal, QC (Canada); Richter, Andrea, E-mail: andrea.richter@umontreal.ca [Genetique Medicale, Centre de Recherche CHU Sainte-Justine, Departement de Pediatrie, Universite de Montreal, Montreal, QC (Canada)
2009-11-01
North American Indian childhood cirrhosis (NAIC/CIRH1A) is a severe autosomal recessive intrahepatic cholestasis. All NAIC patients have a homozygous mutation in CIRH1A that changes conserved Arg565 to Trp (R565W) in Cirhin, a nucleolar protein of unknown function. Subcellular localization is unaffected by the mutation. Yeast two-hybrid screening identified Cirip (Cirhin interaction protein) and found that interaction between Cirip and R565W-Cirhin was weakened. Co-immunoprecipitation of the two proteins from nuclear extracts of HeLa cells strongly supports the yeast two hybrid results. Cirip has essentially the same sequence as the C-terminal of HIVEP1, a regulator of a canonical NF-{kappa}B sequence. Since Cirip has the zinc fingers required for this interaction, we developed an in vitro assay based on this element in mammalian cells to demonstrate functional Cirhin-Cirip interaction. The strong positive effect of Cirip on the NF-{kappa}B sequence was further increased by both Cirhin and R565W-Cirhin. Importantly, the effect of R565W-Cirhin was weaker than that of the wild type protein. We observed increased levels of Cirhin-Cirip complex in nuclear extracts in the presence of this NF-{kappa}B sequence. Our hypothesis is that Cirhin is a transcriptional regulatory factor of this NF-{kappa}B sequence and could be a participant in the regulation of other genes with NF-{kappa}B responsive elements. Since the activities of genes regulated through NF-{kappa}B responsive elements are especially important during development, this interaction may be a key to explain the perinatal appearance of NAIC.
Czech Academy of Sciences Publication Activity Database
Sauvan, P.; Dalimier, E.; Riconda, C.; Oks, E.; Renner, Oldřich; Weber, S.
2010-01-01
Roč. 1, č. 2 (2010), s. 123-128 ISSN 2229-3159 R&D Projects: GA MŠk(CZ) LC528 Institutional research plan: CEZ:AV0Z10100523 Keywords : laser-plasma interaction * PIC plasma model ing * strong quasimonochromatic electric fields * x-ray line broadening * stark effect * floquet theory Subject RIV: BH - Optics, Masers, Lasers http://www.auburn.edu/academic/cosam/departments/physics/iramp/1_2/sauvan_et_al.pdf
International Nuclear Information System (INIS)
Lundberg, Pernilla; Koskinen, Cecilia; Baldock, Paul A.; Loethgren, Hanna; Stenberg, Asa; Lerner, Ulf H.; Oldenborg, Per-Arne
2007-01-01
Physical interaction between the cell surface receptors CD47 and signal regulatory protein alpha (SIRPα) was reported to regulate cell migration, phagocytosis, cytokine production, and macrophage fusion. However, it is unclear if the CD47/SIRPα-interaction can also regulate macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor (NF)-κB ligand (RANKL)-stimulated formation of osteoclasts. Here, we show that functional blocking antibodies to either CD47 or SIRPα strongly reduced formation of multinucleated tartrate-resistant acid phosphatase (TRAP) + osteoclasts in cultures of murine hematopoietic cells, stimulated in vitro by M-CSF and RANKL. In addition, the numbers of osteoclasts formed in M-CSF/RANKL-stimulated bone marrow macrophage cultures from CD47 -/- mice were strongly reduced, and bones of CD47 -/- mice exhibited significantly reduced osteoclast numbers, as compared with wild-type controls. We conclude that the CD47/SIRPα interaction is important for M-CSF/RANKL-stimulated osteoclast formation both in vivo and in vitro, and that absence of CD47 results in decreased numbers of osteoclasts in CD47 -/- mice
Probing Sub-GeV Mass Strongly Interacting Dark Matter with a Low-Threshold Surface Experiment.
Davis, Jonathan H
2017-11-24
Using data from the ν-cleus detector, based on the surface of Earth, we place constraints on dark matter in the form of strongly interacting massive particles (SIMPs) which interact with nucleons via nuclear-scale cross sections. For large SIMP-nucleon cross sections, the sensitivity of traditional direct dark matter searches using underground experiments is limited by the energy loss experienced by SIMPs, due to scattering with the rock overburden and experimental shielding on their way to the detector apparatus. Hence, a surface-based experiment is ideal for a SIMP search, despite the much larger background resulting from the lack of shielding. We show using data from a recent surface run of a low-threshold cryogenic detector that values of the SIMP-nucleon cross section up to approximately 10^{-27} cm^{2} can be excluded for SIMPs with masses above 100 MeV.
Sethy, Dasaratha; Chakraborty, Hirak
2016-10-01
The interfacial properties of the membrane are exceptionally vital in drug-membrane interaction. They not only select out a particular prototropic form of the drug molecule for incorporation, but are also potent enough to induce structural switchover of these drugs in several cases. In this work, we quantitatively monitored the change in dipolar rearrangement of the micellar interface (as a simplified membrane mimic) by measuring the dielectric constant and dipole potential with the micellization of SDS at pH 3.6. The dielectric constant and dipole potential were measured utilizing the fluorescence of polarity sensitive probe, pyrene and potential-sensitive probe, di-8-ANEPPS, respectively. Our study demonstrates that the change in dipolar rearrangement directly influences the switchover equilibrium between the anionic and neutral from of piroxicam. We have further extended our work to evaluate the effect of hydrophobic chain length of the surfactants on the dipolar rearrangement and its effect on the structural switchover of piroxicam. It is interesting that the extent of switchover of piroxicam is directly correlated with the dipolar rearrangement induced bythe varying hydrophobic chain length of the surfactants. To the best of our knowledge, our results constitute the first report to show the dependence of dipole potential on the hydrophobic chain length of the surfactant and demonstrate that the dipolar rearrangement directly tunes the extent of structural switchover of piroxicam, which was so far only intuitive. We consider that this new finding would have promising implication in drug distribution and drug efficacy. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
The Plasma Sheet as Natural Symmetry Plane for Dipolarization Fronts in the Earth's Magnetotail
Frühauff, D.; Glassmeier, K.-H.
2017-11-01
In this work, observations of multispacecraft mission Time History of Events and Macroscale Interactions during Substorms are used for statistical investigation of dipolarization fronts in the near-Earth plasma sheet of the magnetotail. Using very stringent criteria, 460 events are detected in almost 10 years of mission data. Minimum variance analysis is used to determine the normal directions of the phase fronts, providing evidence for the existence of a natural symmetry of these phenomena, given by the neutral sheet of the magnetotail. This finding enables the definition of a local coordinate system based on the Tsyganenko model, reflecting the intrinsic orientation of the neutral sheet and, therefore, the dipolarization fronts. In this way, the comparison of events with very different background conditions is improved. Through this study, the statistical results of Liu, Angelopoulos, Runov, et al. (2013) are both confirmed and extended. In a case study, the knowledge of this plane of symmetry helps to explain the concave curvature of dipolarization fronts in the XZ plane through phase propagation speeds of magnetoacoustic waves. A second case study is presented to determine the central current system of a passing dipolarization front through a constellation of three spacecraft. With this information, a statistical analysis of spacecraft observations above and below the neutral sheet is used to provide further evidence for the neutral sheet as the symmetry plane and the central current system. Furthermore, it is shown that the signatures of dipolarization fronts are under certain conditions closely related to that of flux ropes, indicating a possible relationship between these two transient phenomena.
Strong interactions - quark models
International Nuclear Information System (INIS)
Goto, M.; Ferreira, P.L.
1979-01-01
The variational method is used for the PSI and upsilon family spectra reproduction from the quark model, through several phenomenological potentials, viz.: linear, linear plus coulomb term and logarithmic. (L.C.) [pt
International Nuclear Information System (INIS)
Vugman, N.V.
1973-08-01
The radiation effects in ]Ir III (CN) 6 ] 3- diamagnetic complexe inserted in the KCl lattice and irradiated with electrons of 2MeV by electron spin resonance (ESR) are analysed. Formulas for g and A tensors in the ligand field approximation, are derivated to calculate non coupling electron density in the metal. The X polarization field of inner shells is positive, indicating a 6s function mixture in the non coupling electron molecular orbital. The observed hyperfine structure is assigned to 4 equivalent nitrogen and one non equivalent nitrogen. This hypothesis is verified by experience of isotope substitution with 15 N. The s and p spin density in ligands are calculated and discussed in terms of molecular obitals. The effects of strong quadrupole interaction into the EPR spectra of ]Ir II (CN) 5 ] 3- complex are analysed by MAGNSPEC computer program to diagonalize the Spin Hamiltonian of the system. Empiric rules for EPR espectrum interpretation with strong quadrupole interaction. A review of EPR technique and a review of main concepts of crystal-field and ligand field theories, are also presented. (M.C.K.) [pt
Statistical maps for EEG dipolar source localization.
Bénar, Christian G; Gunn, Roger N; Grova, Christophe; Champagne, Benoît; Gotman, Jean
2005-03-01
We present a method that estimates three-dimensional statistical maps for electroencephalogram (EEG) source localization. The maps assess the likelihood that a point in the brain contains a dipolar source, under the hypothesis of one, two or three activated sources. This is achieved by examining all combinations of one to three dipoles on a coarse grid and attributing to each combination a score based on an F statistic. The probability density function of the statistic under the null hypothesis is estimated nonparametrically, using bootstrap resampling. A theoretical F distribution is then fitted to the empirical distribution in order to allow correction for multiple comparisons. The maps allow for the systematic exploration of the solution space for dipolar sources. They permit to test whether the data support a given solution. They do not rely on the assumption of uncorrelated source time courses. They can be compared to other statistical parametric maps such as those used in functional magnetic resonance imaging (fMRI). Results are presented for both simulated and real data. The maps were compared with LORETA and MUSIC results. For the real data consisting of an average of epileptic spikes, we observed good agreement between the EEG statistical maps, intracranial EEG recordings, and fMRI activations.
Evaluation of uncertainty in alignment tensors obtained from dipolar couplings
International Nuclear Information System (INIS)
Zweckstetter, Markus; Bax, Ad
2002-01-01
Residual dipolar couplings and their corresponding alignment tensors are useful for structural analysis of macromolecules. The error in an alignment tensor, derived from residual dipolar couplings on the basis of a known structure, is determined not only by the accuracy of the measured couplings but also by the uncertainty in the structure (structural noise). This dependence is evaluated quantitatively on the basis of simulated structures using Monte-Carlo type analyses. When large numbers of dipolar couplings are available, structural noise is found to result in a systematic underestimate of the magnitude of the alignment tensor. Particularly in cases where only few dipolar couplings are available, structural noise can cause significant errors in best-fitted alignment tensor values, making determination of the relative orientation of small fragments and evaluation of local backbone mobility from dipolar couplings difficult. An example for the protein ubiquitin demonstrates the inherent limitations in characterizing motions on the basis of local alignment tensor magnitudes
Classical and quantum phases of low-dimensional dipolar systems
Energy Technology Data Exchange (ETDEWEB)
Cartarius, Florian
2016-09-22
In this thesis we present a detailed study of the phase diagram of ultracold bosonic atoms confined along a tight atomic wave guide, along which they experience an optical lattice potential. In this quasi-one dimensional model we analyse the interplay between interactions and quantum fluctuations in (i) determining the non-equilibrium steady state after a quench and (ii) giving rise to novel equilibrium phases, when the interactions combine the s-wave contact interaction and the anisotropic long range dipole-dipole interactions. In detail, in the first part of the thesis we study the depinning of a gas of impenetrable bosons following the sudden switch of of the optical lattice. By means of a Bose-Fermi mapping we infer the exact quantum dynamical evolution and show that in the thermodynamic limit the system is in a non-equilibrium steady state without quasi-long range order. In the second part of the thesis, we study the effect of quantum fluctuations on the linear-zigzag instability in the ground state of ultracold dipolar bosons, as a function of the strength of the transverse confinement. We first analyse the linear-zigzag instability in the classical regime, and then use our results to develop a multi-mode Bose-Hubbard model for the system. We then develop several numerical methods, to determine the ground state.
Pankrats, A. I.; Vorotynov, A. M.; Tugarinov, V. I.; Zharkov, S. M.; Zeer, G. M.; Ramasamy, K.; Gupta, A.
2018-04-01
Magnetic resonance characteristics of mixed chalcospinel nanocrystals CuCr2SxSe4-x (x = 0 and 2) and CoxCu1-xCr2S4 (x = 0.1 and 0.2) have been investigated. It has been established based on TEM, SEM and resonance data that all the samples contain both blocks with sizes from 1 to 50 m of compacted nanosized crystallites and individual nanoparticles with sizes from 10 to 30 nm. The studies provide evidence of strong interparticle interaction in all the samples leading to high values of the blocking temperature. Magnetic dipolar field arise in the boundary regions of interacting adjacent nanocrystals below the blocking temperature. This results in inhomogeneous broadening of the magnetic resonance spectrum along with appearance of additional absorption lines. With increase in magnetic anisotropy at low temperatures, a shift of the resonance field along with line broadening are observed for all the studied compounds due to freezing of the moments in the nanoparticles, both in the individual and compacted ones. A gapped characteristic of the resonance spectrum is established below the freezing temperature Tfr, with the energy gap defined by the averaged magnetic anisotropy . Anionic substitution of sulfur by selenium results in a decrease in the magnetic anisotropy. In contrast, cationic substitution of copper by cobalt increases the magnetic anisotropy due to a strong contribution from the latter ion.
Residual dipolar couplings in sup 3 sup 1 P MAS spectra of PPh sub 3 substituted cobalt complexes
Szalontai, G
2002-01-01
Residual dipolar couplings between sup 3 sup 1 P- sup 5 sup 9 Co spin pairs were studied in sup 3 sup 1 P MAS spectra of mono- and dinuclear cobalt-triphenylphosphine complexes. These spectra can provide important information such as the scalar coupling between the dipolar phosphorus and the quadrupolar cobalt nuclei normally not available from solution phase studies. In case of complementary (NQR or x-ray) data even the relative orientation of the interacting shielding, dipolar, scalar couplings, and electric field gradient tensors or internuclear distances can be determined. Examples are shown both for well resolved and practically unresolved cases, factors which possibly control the spectral resolution are discussed in detail. (author)
Miao, Yuxuan; Zhou, Jia; Chen, Cuicui; Shen, Delong; Song, Wei; Feng, Yongjun
2008-12-01
Pantoea (formerly Enterobacter) agglomerans YS19 is a dominant diazotrophic endophyte isolated from rice (Oryza sativa cv. Yuefu) grown in a temperate-climate region in west Beijing, China. In vitro adsorption and invasion of YS19 on host plant root were studied in this research. Adsorption of YS19 on rice seedling roots closely resembled the Langmuir adsorption and showed a higher adsorption quantity than the control strains Paenibacillus polymyxa WY110 (a rhizospheric bacterium from the same rice cultivar) and Escherichia coli HB101 (a general model bacterium). Adsorption dynamics study revealed high rates and a long duration of the YS19-rice root adsorption process. Adsorption of YS19 was mainly observed on the root hair, though which it enters the plant. This in vitro adsorption study revealed an apparent strong interaction between YS19 and rice at the early endophyte-host recognition stage.
Measurement of the strong-interaction shift and broadening of the ground state of the panti p atom
International Nuclear Information System (INIS)
Ziegler, M.; Duch, K.D.; Heel, M.; Kalinowsky, H.; Kayser, F.; Klempt, E.; Rieger, R.; Schreiber, O.; Straumann, U.; Weidenauer, P.; Ahmad, S.; Comyn, M.; Armenteros, R.; Bailey, D.; Barlag, S.; Gastaldi, U.; Landua, R.; Auld, E.G.; Axen, D.A.; Erdman, K.L.; Howard, B.; Howard, R.; White, B.L.; Beer, G.A.; Marshall, G.M.; Robertson, L.P.; Bizot, J.C.; Delcourt, B.; Jeanjean, J.; Nguyen, H.; Dahme, W.; Feld-Dahme, F.; Schaefer, U.; Wodrich, W.R.; Prevot, N.; Sabev, C.
1988-01-01
The K α X-rays from panti p atoms formed in H 2 gas at normal temperature and pressure are unambiguously identified by coincidences with L X-rays populating the 2P level. Background due to inner bremsstrahlung is suppressed by selecting events annihilating into neutral final states only. The K α line is observed with a significance of more than 25 standard deviations at an energy of 8.67(15) keV. From fits to the K α line we obtain a strong-interaction shift and width of the 1S level, averaged over the unresolved spin singlet and triplet contributions, of ΔE + iΓ/2 = [-0.70(15) + i0.80(2)] keV. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Hou, Guangjin, E-mail: hou@udel.edu, E-mail: tpolenov@udel.edu; Lu, Xingyu, E-mail: luxingyu@udel.edu, E-mail: lexvega@comcast.net; Vega, Alexander J., E-mail: luxingyu@udel.edu, E-mail: lexvega@comcast.net; Polenova, Tatyana, E-mail: hou@udel.edu, E-mail: tpolenov@udel.edu [Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA and Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, Pennsylvania 15261 (United States)
2014-09-14
We report a Phase-Alternating R-Symmetry (PARS) dipolar recoupling scheme for accurate measurement of heteronuclear {sup 1}H-X (X = {sup 13}C, {sup 15}N, {sup 31}P, etc.) dipolar couplings in MAS NMR experiments. It is an improvement of conventional C- and R-symmetry type DIPSHIFT experiments where, in addition to the dipolar interaction, the {sup 1}H CSA interaction persists and thereby introduces considerable errors in the dipolar measurements. In PARS, phase-shifted RN symmetry pulse blocks applied on the {sup 1}H spins combined with π pulses applied on the X spins at the end of each RN block efficiently suppress the effect from {sup 1}H chemical shift anisotropy, while keeping the {sup 1}H-X dipolar couplings intact. Another advantage over conventional DIPSHIFT experiments, which require the signal to be detected in the form of a reduced-intensity Hahn echo, is that the series of π pulses refocuses the X chemical shift and avoids the necessity of echo formation. PARS permits determination of accurate dipolar couplings in a single experiment; it is suitable for a wide range of MAS conditions including both slow and fast MAS frequencies; and it assures dipolar truncation from the remote protons. The performance of PARS is tested on two model systems, [{sup 15}N]-N-acetyl-valine and [U-{sup 13}C,{sup 15}N]-N-formyl-Met-Leu-Phe tripeptide. The application of PARS for site-resolved measurement of accurate {sup 1}H-{sup 15}N dipolar couplings in the context of 3D experiments is presented on U-{sup 13}C,{sup 15}N-enriched dynein light chain protein LC8.
International Nuclear Information System (INIS)
Ahn, Sang Woon; Oh, Se Woung; Ro, Seung Woo
1986-01-01
The NMR chemical shift arising from 4d electron angular momentum and 4d electron angular momentum and 4d electron spin dipolar-nuclear spin angular momentum interactions for a 4d 1 system in a strong crystal field environment of trigonal symmetry, where the threefold axis is chosen to be the axis of quantization axis, has been examined. A general expression using the nonmultipole expansion method (exact method) is derived for the NMR chemical shift. From this expression all the multipolar terms are determined. we observe that along the (100), (010), (110), and (111) axes the NMR chemical shifts are positive while along the (001) axis, it is negative. We observe that the dipolar term (1/R 3 ) is the dominant contribution to the NMR chemical shift except for along the (111) axis. A comparison of the multipolar terms with the exact values shows also that the multipolar results are exactly in agreement with the exact values around R≥0.2 nm. The temperature dependence analysis on the NMR chemical shifts may imply that along the (111) axis the contribution to the NMR chemical shift is dominantly pseudo contact interaction. Separation of the contributions of the Fermi and the pseudo contact interactions would correctly imply that the dipolar interaction is the dominant contribution to the NMR chemical shifts along the (100), (010), (001), and (110) axes, but along the (111) axis the Fermi contact interaction is incorrectly the dominant contribution to the NMR chemical shift. (Author)
Arrays of dipolar molecular rotors in Tris(o-phenylenedioxy) cyclotriphosphazene.
Zhao, Ke; Dron, Paul I; Kaleta, Jiří; Rogers, Charles T; Michl, Josef
2014-01-01
Regular two-dimensional or three-dimensional arrays of mutually interacting dipolar molecular rotors represent a worthy synthetic objective. Their dielectric properties, including possible collective behavior, will be a sensitive function of the location of the rotors, the orientation of their axes, and the size of their dipoles. Host-guest chemistry is one possible approach to gaining fine control over these factors. We describe the progress that has been achieved in recent years using tris (o-phenylenedioxy)cyclotriphosphazene as a host and a series of rod-shaped dipolar molecular rotors as guests. Structures of both surface and bulk inclusion compounds have been established primarily by solid-state nuclear magnetic resonance (NMR) and powder X-ray diffraction (XRD) techniques. Low-temperature dielectric spectroscopy revealed rotational barriers as low as 1.5 kcal/mol, but no definitive evidence for collective behavior has been obtained so far.
Energy Technology Data Exchange (ETDEWEB)
Hauet, T.; Gunther, C.M.; Pfau, B.; Eisebitt, S.; Fischer, P.; Rick, R. L.; Thiele, J.-U.; Hellwig, O.; Schabes, M.E.
2007-07-01
Dipolar interactions in a soft/Pd/hard [CoNi/Pd]{sub 30}/Pd/[Co/Pd]{sub 20} multilayer system, where a thick Pd layer between two ferromagnetic units prevents direct exchange coupling, are directly revealed by combining magnetometry and state-of-the-art layer resolving soft x-ray imaging techniques with sub-100-nm spatial resolution. The domains forming in the soft layer during external magnetic field reversal are found to match the domains previously trapped in the hard layer. The low Curie temperature of the soft layer allows varying its intrinsic parameters via temperature and thus studying the competition with dipolar fields due to the domains in the hard layer. Micromagnetic simulations elucidate the role of [CoNi/Pd] magnetization, exchange, and anisotropy in the duplication process. Finally, thermally driven domain replication in remanence during temperature cycling is demonstrated.
A Time-Splitting and Sine Spectral Method for Dynamics of Dipolar Bose-Einstein Condensate
Directory of Open Access Journals (Sweden)
Si-Qi Li
2013-01-01
Full Text Available A two-component Bose-Einstein condensate (BEC described by two coupled a three-dimension Gross-Pitaevskii (GP equations is considered, where one equation has dipole-dipole interaction while the other one has only the usual s-wave contact interaction, in a cigar trap. The time-splitting and sine spectral method in space is proposed to discretize the time-dependent equations for computing the dynamics of dipolar BEC. The singularity in the dipole-dipole interaction brings significant difficulties both in mathematical analysis and in numerical simulations. Numerical results are given to show the efficiency of this method.
Topological defect formation in rotating binary dipolar Bose–Einstein condensate
Energy Technology Data Exchange (ETDEWEB)
Zhang, Xiao-Fei, E-mail: xfzhang@ntsc.ac.cn [Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi’an 710600 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Department of Engineering Science, University of Electro-Communications, Tokyo 182-8585 (Japan); Han, Wei [Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi’an 710600 (China); Jiang, Hai-Feng [Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi’an 710600 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Liu, Wu-Ming [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Saito, Hiroki [Department of Engineering Science, University of Electro-Communications, Tokyo 182-8585 (Japan); Zhang, Shou-Gang [Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi’an 710600 (China); University of Chinese Academy of Sciences, Beijing 100049 (China)
2016-12-15
We investigate the topological defects and spin structures of a rotating binary Bose–Einstein condensate, which consists of both dipolar and scalar bosonic atoms confined in spin-dependent optical lattices, for an arbitrary orientation of the dipoles with respect to their plane of motion. Our results show that the tunable dipolar interaction, especially the orientation of the dipoles, can be used to control the direction of stripe phase and its related half-vortex sheets. In addition, it can also be used to obtain a regular arrangement of various topological spin textures, such as meron, circular and cross disgyration spin structures. We point out that such topological defects and regular arrangement of spin structures arise primarily from the long-range and anisotropic nature of dipolar interaction and its competition with the spin-dependent optical lattices and rotation. - Highlights: • Effects of both strength and orientation of the dipoles are discussed. • Various topological defects can be formed in different parameter regions. • Present one possible way to obtain regular arrangements of spin textures.
International Nuclear Information System (INIS)
Senda Ikuo.
1991-05-01
We propose dynamical models of hadrons, the nucleation model and the free-decay model, in which results of string model are used to represent interactions. The dynamical properties of hadrons, which are obtained by string model, are examined and their parameters are fitted by experimental data. The equilibrium properties of hadrons at high density are investigated by the nucleation model and we found a singular behaviour at energy density 3 ∼ 5 GeV/fm 3 , where hadrons coalesce to create highly excited states. We argue that this singular behaviour corresponds to the phase transition to quark-gluon plasma. The possibility to observe the production of high density strongly interacting matter at collider experiments are discussed using the free-decay model, which produces pion distributions as decay products of resonances. We show that our free-decay model recovers features of hadron distributions obtained in hadron collision experiments. Finally the perspectives and extensions are discussed. (author). 34 refs, 19 figs, 2 tabs
Characterizing Ion Flows Across a Dipolarization Front
Arnold, H.; Drake, J. F.; Swisdak, M.
2017-12-01
In light of the Magnetospheric Multiscale Mission (MMS) moving to study predominately symmetric magnetic reconnection in the Earth's magnetotail, it is of interest to investigate various methods for determining the relative location of the satellites with respect to the x line or a dipolarization front. We use a 2.5 dimensional PIC simulation to explore the dependence of various characteristics of a front, or flux bundle, on the width of the front in the dawn-dusk direction. In particular, we characterize the ion flow in the x-GSM direction across the front. We find a linear relationship between the width of a front, w, and the maximum velocity of the ion flow in the x-GSM direction, Vxi, for small widths: Vxi/VA=w/di*1/2*(mVA2)/Ti*Bz/Bxwhere m, VA, di, Ti, Bz, and Bx are the ion mass, upstream Alfven speed, ion inertial length, ion temperature, and magnetic fields in the z-GSM and x-GSM directions respectively. However, once the width reaches around 5 di, the relationship gradually approaches the well-known theoretical limit for ion flows, the upstream Alfven speed. Furthermore, we note that there is a reversal in the Hall magnetic field near the current sheet on the positive y-GSM side of the front. This reversal is most likely due to conservation of momentum in the y-GSM direction as the ions accelerate towards the x-GSM direction. This indicates that while the ions are primarily energized in the x-GSM direction by the front, they transfer energy to the electromagnetic fields in the y-GSM direction. The former energy transfer is greater than the latter, but the reversal of the Hall magnetic field drags the frozen-in electrons along with it outside of the front. These simulations should better able researchers to determine the relative location of a satellite crossing a dipolarization front.
Conformal field theory of dipolar SLE with the Dirichlet boundary condition
Kang, Nam-Gyu; Tak, Hee-Joon
2013-12-01
We develop a version of dipolar conformal field theory based on the central charge modification of the Gaussian free field with the Dirichlet boundary condition and prove that correlators of certain family of fields in this theory are martingale-observables for dipolar SLE. We prove the restriction property of dipolar SLE(8/3) and Friedrich-Werner's formula in the dipolar case.
Effects of strong interactions between Ti and ceria on the structures of Ti/CeO2.
Yao, Xiao-Dan; Zhu, Kong-Jie; Teng, Bo-Tao; Yu, Cao-Ming; Zhang, Yun-Lei; Liu, Ya; Fan, Maohong; Wen, Xiao-Dong
2016-11-30
The effects of strong interactions between Ti and ceria on the structures of Ti/CeO 2 (111) are systematically investigated by density functional theory calculation. To our best knowledge, the adsorption energy of a Ti atom at the hollow site of CeO 2 is the highest value (-7.99 eV) reported in the literature compared with those of Au (-0.88--1.26 eV), Ag (-1.42 eV), Cu (-2.69 eV), Pd (-1.75 eV), Pt (-2.62 eV) and Sn (-3.68 eV). It is very interesting to find that Ti adatoms disperse at the hollow site of CeO 2 (111) to form surface TiO x species, instead of aggregating to form Ti metal clusters for the Ti-CeO 2 interactions that are much stronger than those of Ti-Ti ones. Ti adatoms are completely oxidized to Ti 4+ ions if they are monatomically dispersed on the next near hollow sites of CeO 2 (111) (xTi-NN-hollow); while Ti 3+ ions are observed when they locate at the near hollow sites (xTi-N-hollow). Due to the electronic repulsive effects among Ti 3+ ions, the adsorption energies of xTi-N-hollow are slightly weaker than those of xTi-NN-hollow. Simultaneously, the existence of unstable Ti 3+ ions on xTi-N-hollow also leads to the restructuring of xTi-N-hollow by surface O atoms of ceria transferring to the top of Ti 3+ ions, or oxidation by O 2 adsorption and dissociation. Both processes improve the stability of the xTi/CeO 2 system by Ti 3+ oxidation. Correspondingly, surface TiO 2 -like species form. This work sheds light into the structures of metal/CeO 2 catalysts with strong interactions between the metal and the ceria support.
Physics of Substorm Growth Phase, Onset, and Dipolarization
Energy Technology Data Exchange (ETDEWEB)
C.Z. Cheng
2003-10-22
A new scenario of substorm growth phase, onset, and depolarization during expansion phase and the corresponding physical processes are presented. During the growth phase, as a result of enhanced plasma convection, the plasma pressure and its gradient are continued to be enhanced over the quiet-time values in the plasma sheet. Toward the late growth phase, a strong cross-tail current sheet is formed in the near-Earth plasma sheet region, where a local magnetic well is formed, the plasma beta can reach a local maximum with value larger than 50 and the cross-tail current density can be enhanced to over 10nA/m{sup 2} as obtained from 3D quasi-static magnetospheric equilibrium solutions for the growth phase. The most unstable kinetic ballooning instabilities (KBI) are expected to be located in the tailward side of the strong cross-tail current sheet region. The field lines in the most unstable KBI region map to the transition region between the region-1 and region-2 currents in the ionosphere, which is consistent with the observed initial brightening location of the breakup arc in the intense proton precipitation region. The KBI explains the AMPTE/CCE observations that a low-frequency instability with a wave period of 50-75 seconds is excited about 2-3 minutes prior to substorm onset and grows exponentially to a large amplitude at the onset of current disruption (or current reduction). At the current disruption onset higher frequency instabilities are excited so that the plasma and electromagnetic field fluctuations form a strong turbulent state. Plasma transport takes place due to the strong turbulence to relax the ambient plasma pressure profile so that the plasma pressure and current density are reduced and the ambient magnetic field intensity increases by more than a factor of 2 in the high-beta(sub)eq region and the field line geometry recovers from tail-like to dipole-like dipolarization.
Gálvez, Loli; González, Esther M; Arrese-Igor, Cesar
2005-09-01
Symbiotic N2 fixation in legume nodules declines under a wide range of environmental stresses. A high correlation between N2 fixation decline and sucrose synthase (SS; EC 2.4.1.13) activity down-regulation has been reported, although it has still to be elucidated whether a causal relationship between SS activity down-regulation and N2 fixation decline can be established. In order to study the likely C/N interactions within nodules and the effects on N2 fixation, pea plants (Pisum sativum L. cv. Sugar snap) were subjected to progressive water stress by withholding irrigation. Under these conditions, nodule SS activity declined concomitantly with apparent nitrogenase activity. The levels of UDP-glucose, glucose-1-phosphate, glucose-6-phosphate, and fructose-6-phosphate decreased in water-stressed nodules compared with unstressed nodules. Drought also had a marked effect on nodule concentrations of malate, succinate, and alpha-ketoglutarate. Moreover, a general decline in nodule adenylate content was detected. NADP+-dependent isocitrate dehydrogenase (ICDH; EC 1.1.1.42) was the only enzyme whose activity increased as a result of water deficit, compensating for a possible C/N imbalance and/or supplying NADPH in circumstances that the pentose phosphate pathway was impaired, as suggested by the decline in glucose-6-phosphate dehydrogenase (G6PDH; EC 1.1.1.49) activity. The overall results show the occurrence of strong C/N interactions in nodules subjected to water stress and support a likely limitation of carbon flux that might be involved in the decline of N2 fixation under drought.
Palin, L.; Jacquey, C.; Opgenoorth, H.; Connors, M.; Sergeev, V.; Sauvaud, J.-A.; Nakamura, R.; Reeves, G. D.; Singer, H. J.; Angelopoulos, V.; Turc, L.
2015-05-01
We present a case study of eight successive plasma sheet (PS) activations (usually referred to as bursty bulk flows or dipolarization fronts), associated with small individual BZGSM increases on 31 March 2009 (0200-0900 UT), observed by the Time History of Events and Macroscale Interactions During Substorms mission. This series of events happens during very quiet solar wind conditions, over a period of 7 h preceding a substorm onset at 1230 UT. The amplitude of the dipolarizations increases with time. The low-amplitude dipolarization fronts are associated with few (1 or 2) rapid flux transport events (RFT, Eh>2 mV/m), whereas the large-amplitude ones encompass many more RFT events. All PS activations are associated with small and localized substorm current wedge (SCW)-like current system signatures, which seems to be the consequence of RFT arrival in the near tail. The associated ground magnetic perturbations affect a larger part of the contracted auroral oval when, in the magnetotail, more RFT are embedded in PS activations (>5). Dipolarization fronts with very low amplitude, a type usually not included in statistical studies, are of particular interest because we found even those to be associated with clear small SCW-like current system and particle injections at geosynchronous orbit. This exceptional data set highlights the role of flow bursts in the magnetotail and leads to the conclusion that we may be observing the smallest form of a substorm or rather its smallest element. This study also highlights the gradual evolution of the ionospheric current disturbance as the plasma sheet is observed to heat up.
Tsuchimochi, Takashi
2015-10-14
Spin-flip approaches capture static correlation with the same computational scaling as the ordinary single reference methods. Here, we extend spin-flip configuration interaction singles (SFCIS) by projecting out intrinsic spin-contamination to make it spin-complete, rather than by explicitly complementing it with spin-coupled configurations. We give a general formalism of spin-projection for SFCIS, applicable to any spin states. The proposed method is viewed as a natural unification of SFCIS and spin-projected CIS to achieve a better qualitative accuracy at a low computational cost. While our wave function ansatz is more compact than previously proposed spin-complete SF approaches, it successfully offers more general static correlation beyond biradicals without sacrificing good quantum numbers. It is also shown that our method is invariant with respect to open-shell orbital rotations, due to the uniqueness of spin-projection. We will report benchmark calculations to demonstrate its qualitative performance on strongly correlated systems, including conical intersections that appear both in ground-excited and excited-excited degeneracies.
Energy Technology Data Exchange (ETDEWEB)
Liao, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Venugopalan, R. [Brookhaven National Lab. (BNL), Upton, NY (United States); Berges, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Blaizot, J. -P. [Brookhaven National Lab. (BNL), Upton, NY (United States); Gelis, F. [Brookhaven National Lab. (BNL), Upton, NY (United States)
2014-04-09
The RIKEN BNL Research Center (RBRC) was established in April 1997 at Brookhaven National Laboratory*. It is funded by the ''Rikagaku Kenkyusho'' (RIKEN, The Institute of Physical and Chemical Research) of Japan and the U. S. Department of Energy’s Office of Science. The RBRC is dedicated to the study of strong interactions, including spin physics, lattice QCD, and RHIC physics through the nurturing of a new generation of young physicists. The RBRC has theory, lattice gauge computing and experimental components. It is presently exploring the possibility of an astrophysics component being added to the program. The purpose of this Workshop is to critically review the recent progress on the theory and phenomenology of early time dynamics in relativistic heavy ion collisions from RHIC to LHC energies, to examine the various approaches on thermalization and existing issues, and to formulate new research efforts for the future. Topics slated to be covered include Experimental evidence for equilibration/isotropization, comparison of various approaches, dependence on the initial conditions and couplings, and turbulent cascades and Bose-Einstein condensation.
Measurement of the strong interaction coupling constant αs by jet study in the H1 experiment
International Nuclear Information System (INIS)
Squinabol, F.
1997-01-01
The H1 experiment allows to study hadronic jets produced in deep inelastic lepton (27.5 GeV) scattering off protons (820 GeV). The coupling constant of the strong interaction α s can be extracted from the measurement of the 2-jets rate in the final state. The use of the JADE algorithm is optimal for events with high energy transfer (100-4,000 GeV 2 ), corresponding to the 1994 and 1995 data. The error on α s (M Z 0 2 ) is dominated by the uncertainty from the hadronic energy measurement and the experimental resolution effects on jets. The theoretical error is dominated by the renormalization scale dependence. The final result is (M Z 0 2 ) 0.118 -0.008 +0.008 . This analysis is extended to smaller momentum transfers (25-100 GeV 2 ) using the factorizable K t algorithm, taking the transferred momentum as energy scale of the particle re-clustering. The result α s (M Z 0 2 ) 0.117 -0.008 +0.009 is compatible with the previous one. The precision of the measurement performed in this thesis is 7%. A precision of 4% could be achieved after progresses in the theoretical framework and/or after a significant increase of the luminosity. (author)
Energy Technology Data Exchange (ETDEWEB)
Ruhl, Hartmut [Munich Univ. (Germany). Chair for Computational and Plasma Physics
2016-11-01
Since the installation of SuperMUC phase 2 the 9216 nodes of phase 1 are more easily available for large scale runs allowing for the thin foil and AWAKE simulations. Besides phase 2 could be used in parallel for high throughput of the ion acceleration simulations. Challenging to our project were the full-volume checkpoints required by PIC that strained the I/O-subsystem of SuperMUC to its limits. New approaches considered for the next generation system, like burst buffers could overcome this bottleneck. Additionally, as the FDTD solver in PIC is strongly bandwidth bound, PSC will benefit profoundly from high-bandwidth memory (HBM) that most likely will be available in future HPC machines. This will be of great advantage as in 2018 phase II of AWAKE should begin, with a longer plasma channel further increasing the need for additional computing resources. Last but not least, it is expected that our methods used in plasma physics (many body interaction with radiation) will be more and more adapted for medical diagnostics and treatments. For this research field we expect centimeter sized volumes with necessary resolutions of tens of micro meters resulting in boxes of >10{sup 12} voxels (100-200 TB) on a regular basis. In consequence the demand for computing time and especially for data storage and data handling capacities will also increase significantly.
Critical phase transitions of three-dimensional Ising-like dipolar ferromagnets
Energy Technology Data Exchange (ETDEWEB)
Nicolaides, Demetris
2001-06-01
In ferromagnets with low critical temperatures, dipolar interactions are the reason for the reduction of the critical dimension above which mean-field behavior prevails. Specifically, it is shown that a three-dimensional uniaxial system with dipole{endash}dipole interactions falls into the universality class of a four-dimensional strictly short-range system, whose behavior is mean field with subtle logarithmic corrections which reflect the nonmean-field behavior that sets in fully below four space dimensions. {copyright} 2001 American Institute of Physics.
Asymptotic behavior of local dipolar fields in thin films
Energy Technology Data Exchange (ETDEWEB)
Bowden, G.J., E-mail: gjb@phys.soton.ac.uk [School of Physics and Astronomy, University of Southampton, SO17 1BJ (United Kingdom); Stenning, G.B.G., E-mail: Gerrit.vanderlaan@diamond.ac.uk [Magnetic Spectroscopy Group, Diamond Light Source, Didcot OX11 0DE (United Kingdom); Laan, G. van der, E-mail: gavin.stenning@stfc.ac.uk [ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Didcot OX11 0QX (United Kingdom)
2016-10-15
A simple method, based on layer by layer direct summation, is used to determine the local dipolar fields in uniformly magnetized thin films. The results show that the dipolar constants converge ~1/m where the number of spins in a square film is given by (2m+1){sup 2}. Dipolar field results for sc, bcc, fcc, and hexagonal lattices are presented and discussed. The results can be used to calculate local dipolar fields in films with either ferromagnetic, antiferromagnetic, spiral, exponential decay behavior, provided the magnetic order only changes normal to the film. Differences between the atomistic (local fields) and macroscopic fields (Maxwellian) are also examined. For the latter, the macro B-field inside the film is uniform and falls to zero sharply outside, in accord with Maxwell boundary conditions. In contrast, the local field for the atomistic point dipole model is highly non-linear inside and falls to zero at about three lattice spacing outside the film. Finally, it is argued that the continuum field B (used by the micromagnetic community) and the local field B{sub loc}(r) (used by the FMR community) will lead to differing values for the overall demagnetization energy. - Highlights: • Point-dipolar fields in uniformly magnetized thin films are characterized by just three numbers. • Maxwell's boundary condition is partially violated in the point-dipole approximation. • Asymptotic values of point dipolar fields in circular monolayers scale as π/r.
Evaporative cooling of the dipolar hydroxyl radical.
Stuhl, Benjamin K; Hummon, Matthew T; Yeo, Mark; Quéméner, Goulven; Bohn, John L; Ye, Jun
2012-12-20
Atomic physics was revolutionized by the development of forced evaporative cooling, which led directly to the observation of Bose-Einstein condensation, quantum-degenerate Fermi gases and ultracold optical lattice simulations of condensed-matter phenomena. More recently, substantial progress has been made in the production of cold molecular gases. Their permanent electric dipole moment is expected to generate systems with varied and controllable phases, dynamics and chemistry. However, although advances have been made in both direct cooling and cold-association techniques, evaporative cooling has not been achieved so far. This is due to unfavourable ratios of elastic to inelastic scattering and impractically slow thermalization rates in the available trapped species. Here we report the observation of microwave-forced evaporative cooling of neutral hydroxyl (OH(•)) molecules loaded from a Stark-decelerated beam into an extremely high-gradient magnetic quadrupole trap. We demonstrate cooling by at least one order of magnitude in temperature, and a corresponding increase in phase-space density by three orders of magnitude, limited only by the low-temperature sensitivity of our spectroscopic thermometry technique. With evaporative cooling and a sufficiently large initial population, much colder temperatures are possible; even a quantum-degenerate gas of this dipolar radical (or anything else it can sympathetically cool) may be within reach.
Pham, Tran N; Hinchley, Sarah L; Rankin, David W H; Liptaj, Tibor; Uhrín, Dusan
2004-10-13
We have developed methodology for the determination of solution structures of small molecules from residual dipolar coupling constants measured in dilute liquid crystals. The power of the new technique is demonstrated by the determination of the structure of methyl beta-d-xylopyranoside (I) in solution. An oriented sample of I was prepared using a mixture of C(12)E(5) and hexanol in D(2)O. Thirty residual dipolar coupling constants, ranging from -6.44 to 4.99 Hz, were measured using intensity-based J-modulated NMR techniques. These include 15 D(HH), 4 (1)D(CH), and 11 (n)D(CH) coupling constants. The accuracy of the dipolar coupling constants is estimated to be Comparison with the neutron diffraction structure showed larger differences attributable to crystal packing effects. Reducing the degree of order by using dilute liquid crystalline media in combination with precise measurement of small residual dipolar coupling constants, as shown here, is a way of overcoming the limitation of strongly orienting liquid crystals associated with the complexity of (1)H NMR spectra for molecules with more than 12 protons.
Jet Dipolarity: Top Tagging with Color Flow
Energy Technology Data Exchange (ETDEWEB)
Hook, Anson; Jankowiak, Martin; /SLAC /Stanford U., Phys. Dept.; Wacker, Jay G.; /SLAC
2011-08-12
A new jet observable, dipolarity, is introduced that can distinguish whether a pair of subjets arises from a color singlet source. This observable is incorporated into the HEPTopTagger and is shown to improve discrimination between top jets and QCD jets for moderate to high p{sub T}. The impressive resolution of the ATLAS and CMS detectors means that a typical QCD jet at the LHC deposits energy in {Omicron}(10-100) calorimeter cells. Such fine-grained calorimetry allows for jets to be studied in much greater detail than previously, with sophisticated versions of current techniques making it possible to measure more than just the bulk properties of jets (e.g. event jet multiplicities or jet masses). One goal of the LHC is to employ these techniques to extend the amount of information available from each jet, allowing for a broader probe of the properties of QCD. The past several years have seen significant progress in developing such jet substructure techniques. A number of general purpose tools have been developed, including: (i) top-tagging algorithms designed for use at both lower and higher p{sub T} as well as (ii) jet grooming techniques such as filtering, pruning, and trimming, which are designed to improve jet mass resolution. Jet substructure techniques have also been studied in the context of specific particle searches, where they have been shown to substantially extend the reach of traditional search techniques in a wide variety of scenarios, including for example boosted Higgses, neutral spin-one resonances, searches for supersymmetry, and many others. Despite these many successes, however, there is every reason to expect that there remains room for refinement of jet substructure techniques.
Fluctuation-dissipation theorem in an isolated system of quantum dipolar bosons after a quench.
Khatami, Ehsan; Pupillo, Guido; Srednicki, Mark; Rigol, Marcos
2013-08-02
We examine the validity of fluctuation-dissipation relations in isolated quantum systems taken out of equilibrium by a sudden quench. We focus on the dynamics of trapped hard-core bosons in one-dimensional lattices with dipolar interactions whose strength is changed during the quench. We find indications that fluctuation-dissipation relations hold if the system is nonintegrable after the quench, as well as if it is integrable after the quench if the initial state is an equilibrium state of a nonintegrable Hamiltonian. On the other hand, we find indications that they fail if the system is integrable both before and after quenching.
Anisotropic properties of phase separation in two-component dipolar Bose-Einstein condensates
Wang, Wei; Li, Jinbin
2018-03-01
Using Crank-Nicolson method, we calculate ground state wave functions of two-component dipolar Bose-Einstein condensates (BECs) and show that, due to dipole-dipole interaction (DDI), the condensate mixture displays anisotropic phase separation. The effects of DDI, inter-component s-wave scattering, strength of trap potential and particle numbers on the density profiles are investigated. Three types of two-component profiles are present, first cigar, along z-axis and concentric torus, second pancake (or blood cell), in xy-plane, and two non-uniform ellipsoid, separated by the pancake and third two dumbbell shapes.
Understanding the anisotropic ion distributions within magnetotail dipolarizing flux bundles
Zhou, X.; Runov, A.; Angelopoulos, V.; Birn, J.
2017-12-01
Dipolarizing flux bundles (DFBs), earthward-propagating structures with enhanced northward magnetic field (Bz) component, are usually believed to carry a different plasma population from that in the ambient magnetotail plasma sheet. The ion distribution functions within the DFB, however, are recently found to be largely controlled by the ion adiabaticity parameter κ in the ambient plasma sheet outside the DFBs. According to these observations, the ambient κ values of 2-3 usually correspond to a strong perpendicular anisotropy of suprathermal ions within the DFBs, whereas for lower κ values the ions inside the DFBs become more isotropic. Here we utilize a simple, test-particle model to explore the nature of the anisotropy and its dependence on the ambient κ values. We find that the ion anisotropy originates from successive ion reflections and reentries to the DFBs, during which the ions can be consecutively accelerated in the perpendicular direction by the DFB-carried electric field. This acceleration process may be interrupted, however, when the magnetic field lines are highly curved in the ambient plasma sheet. In this case, the ion trajectories are most stochastic outside the DFB region, which makes the reflected ions less likely to return to the DFBs for another cycle of acceleration; as a consequence, the perpendicular ion anisotropy does not appear. Given that the DFB ions are a free energy source for instabilities when they are injected towards Earth, our simple model (that reproduces most observational features on the anisotropic DFB ion distributions) may shed new lights on the coupling process between the magnetotail and the inner magneosphere.
Reactive Collisions and Interactions of Ultracold Dipolar Atoms
2014-10-29
have used Mtot = −16 and even ` ≤ 20. Figure 3 shows the elastic rate coefficients for collisions between two m = -6 168Er atoms in range of magnetic...10 -12 10 -11 10 -10 10 -9 E la st ic r at e (c m 3 / s) FIG. 3: Elastic rate coefficient of m = −6 168Er collisions as a function of magnetic...located in a magneto -optical trap [13]. The experiment was performed in the group of Dr. E. Hudson at UCLA. Evaluation of how well molecular ions are
Long-Lived Spin-Orbit-Coupled Degenerate Dipolar Fermi Gas
Directory of Open Access Journals (Sweden)
Nathaniel Q. Burdick
2016-08-01
Full Text Available We describe the creation of a long-lived spin-orbit-coupled gas of quantum degenerate atoms using the most magnetic fermionic element, dysprosium. Spin-orbit coupling arises from a synthetic gauge field created by the adiabatic following of degenerate dressed states composed of optically coupled components of an atomic spin. Because of dysprosium’s large electronic orbital angular momentum and large magnetic moment, the lifetime of the gas is limited not by spontaneous emission from the light-matter coupling, as for gases of alkali-metal atoms, but by dipolar relaxation of the spin. This relaxation is suppressed at large magnetic fields due to Fermi statistics. We observe lifetimes up to 400 ms, which exceeds that of spin-orbit-coupled fermionic alkali atoms by a factor of 10–100 and is close to the value obtained from a theoretical model. Elastic dipolar interactions are also observed to influence the Rabi evolution of the spin, revealing an interacting fermionic system. The long lifetime of this weakly interacting spin-orbit-coupled degenerate Fermi gas will facilitate the study of quantum many-body phenomena manifest at longer time scales, with exciting implications for the exploration of exotic topological quantum liquids.
Nonlocal and nonlinear electrostatics of a dipolar Coulomb fluid.
Sahin, Buyukdagli; Ralf, Blossey
2014-07-16
We study a model Coulomb fluid consisting of dipolar solvent molecules of finite extent which generalizes the point-like dipolar Poisson-Boltzmann model (DPB) previously introduced by Coalson and Duncan (1996 J. Phys. Chem. 100 2612) and Abrashkin et al (2007 Phys. Rev. Lett. 99 077801). We formulate a nonlocal Poisson-Boltzmann equation (NLPB) and study both linear and nonlinear dielectric response in this model for the case of a single plane geometry. Our results shed light on the relevance of nonlocal versus nonlinear effects in continuum models of material electrostatics.
Energy conversion and dissipation at dipolarization fronts: Theory, modeling and MMS observations
Sitnov, M. I.; Motoba, T.; Merkin, V. G.; Ohtani, S.; Cohen, I. J.; Mauk, B.; Vines, S. K.; Anderson, B. J.; Moore, T. E.; Torbert, R. B.; Giles, B. L.; Burch, J. L.
2017-12-01
Magnetic reconnection is one of the most important energy conversion mechanisms in space plasmas. In the classical picture it converts the energy of antiparallel magnetic fields into the kinetic and thermal energy of accelerated plasma particles in reconnection exhausts. It also involves energy dissipation near the X-line. This classical picture may be substantially modified in real space plasma configurations, such as the dayside magnetopause and the magnetotail. In particular, in the magnetotail the flows of accelerated particles may be strongly asymmetric along the tail with the domination of earthward flows. At the same time, strong energy conversion and even dissipation may occur away from the X-line, in particular, at dipolarization fronts. Here we present a theoretical picture of spontaneous magnetotail reconnection based on 3-D PIC simulations with the focus on plasma bulk flows, energy conversion and dissipation. This picture is compared with some observations from the MMS tail season. An important finding from these observations is that dipolarizations fronts may not only be regions of the total energy conversion with jE>0, but they may also be the sites of energy dissipation, both positive (jE'>0, E' is the electric field E in the system moving with one of the plasma species) and negative (jE'<0). Observations are further compared with theory and modeling that predict the specific location and sign of the energy dissipation at fronts depending on their evolution phase (e.g., formation, propagation, braking).
DFT study of the mechanism and stereoselectivity of the 1,3-dipolar ...
Indian Academy of Sciences (India)
Keywords. Pyrroline-1-oxide; dipolar cycloaddition; optimized structures; stereoselectivity; DFT-based reactivity indices. 1. Introduction. 1,3-Dipolar cycloaddition (1,3-DC) is one of the sim- plest approaches for the construction of five-membered ... An ana- lysis of potential energy surfaces (PESs) shows that these 1,3-dipolar ...
DEFF Research Database (Denmark)
Van Vlack, C.; Kristensen, Philip Trøst; Hughes, S.
2012-01-01
the dot to the detector, we demonstrate that the strong-coupling regime should be observable in the far-field spontaneous emission spectrum, even at room temperature. The vacuum-induced emission spectra show that the usual vacuum Rabi doublet becomes a rich spectral triplet or quartet with two of the four...
Energy Technology Data Exchange (ETDEWEB)
Casalderrey-Solana, Jorge [Departament d' Estructura i Constituents de la Matèria and Institut de Ciències del Cosmos (ICCUB), Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona (Spain); Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP (United Kingdom); Gulhan, Doga Can [Laboratory for Nuclear Science and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Milhano, José Guilherme [CENTRA, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, P-1049-001 Lisboa (Portugal); Physics Department, Theory Unit, CERN, CH-1211 Genève 23 (Switzerland); Pablos, Daniel [Departament d' Estructura i Constituents de la Matèria and Institut de Ciències del Cosmos (ICCUB), Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona (Spain); Rajagopal, Krishna [Laboratory for Nuclear Science and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)
2016-12-15
Within a hybrid strong/weak coupling model for jets in strongly coupled plasma, we explore jet modifications in ultra-relativistic heavy ion collisions. Our approach merges the perturbative dynamics of hard jet evolution with the strongly coupled dynamics which dominates the soft exchanges between the fast partons in the jet shower and the strongly coupled plasma itself. We implement this approach in a Monte Carlo, which supplements the DGLAP shower with the energy loss dynamics as dictated by holographic computations, up to a single free parameter that we fit to data. We then augment the model by incorporating the transverse momentum picked up by each parton in the shower as it propagates through the medium, at the expense of adding a second free parameter. We use this model to discuss the influence of the transverse broadening of the partons in a jet on intra-jet observables. In addition, we explore the sensitivity of such observables to the back-reaction of the plasma to the passage of the jet.
Gregory, D. M.; Mitchell, D. J.; Stringer, J. A.; Kiihne, S.; Shiels, J. C.; Callahan, J.; Mehta, M. A.; Drobny, G. P.
1995-12-01
A new homonuclear dipolar recoupling technique is described which uses a sequence of phase-shifted, windowless irradiations applied synchronously with sample spinning. Experiments performed on a series of doubly labeled dicarboxylic acids, alanine-1,3- 13C 2, and 2'-deoxythymidine-4,6- 13C 2 demonstrate that this new windowless dipolar recoupling pulse sequence can accurately determine internuclear distances from polycrystalline solids in cases where the coupled spins have large chemical shift anisotropies and large differences in isotropic chemical shift.
Keren, Yonatan; Borisover, Mikhail; Schaumann, Gabriele E.; Diehl, Dörte; Tamimi, Nisreen; Bukhanovsky, Nadezhda
2017-04-01
Sorption interactions with soils are well known to control the environmental fate of multiple organic compounds including pesticides. Pesticide-soil interactions may be affected by organic amendments or organic matter (OM)-containing wastewater brought to the field. Specifically, land spreading of olive mill wastewater (OMW), occurring intentionally or not, may also influence pesticide-soil interactions. The effects of the OMW disposed in the field on soil properties, including their ability to interact with pesticides, become of great interest due to the increasing demand for olive oil and a constant growth of world oil production. This paper summarizes some recent findings related to the effect of prior OMW land application on the ability of soils to interact with the organic compounds including pesticides, diuron and simazine. The major findings are as following: (1) bringing OMW to the field increases the potential of soils to sorb non-ionized pesticides; (2) this sorption increase may not be related solely to the increase in soil organic carbon content but it can reflect also the changes in the soil sorption mechanisms; (3) increased pesticide interactions with OMW-affected soils may become irreversible, due, assumedly, to the swelling of some components of the OMW-treated soil; (4) enhanced pesticide-soil interactions mitigate with the time passed after the OMW application, however, in the case of diuron, the remaining effect could be envisioned at least 600 days after the normal OMW application; (5) the enhancement effect of OMW application on soil sorption may increase with soil depth, in the 0-10 cm interval; (6) at higher pesticide (diuron) concentrations, larger extents of sorption enhancement, following the prior OMW-soil interactions, may be expected; (7) disposal of OMW in the field may be seasonal-dependent, and, in the case studied, it led to more distinct impacts on sorption when carried out in spring and winter, as compared with summer. It appears
Energy Technology Data Exchange (ETDEWEB)
Brun, Ch
1998-04-02
In the context of thermal-hydraulics of nuclear reactors, strong interaction between wakes is encountered in the bottom of reactor vessels where control and measurement rods of variable size and disposition interact with the overall wakes generated in these flow zones. This study deals with the strong interaction between two wakes developed downstream of two parallel cylinders with a small spacing. The analysis focusses on the effect of the Reynolds regime which controls the equilibrium between the inertia and viscosity forces of the fluid and influences the large scale behaviour of the flow with the development of hydrodynamic instabilities and turbulence. The document is organized as follows: the characteristic phenomena of wakes formation downstream of cylindrical obstacles are recalled in the first chapter (single cylinder, interaction between two tubes, case of a bundle of tubes perpendicular to the flow). The experimental setup (hydraulic loop, velocity and pressure measurement instrumentation) and the statistical procedures applied to the signals measured are detailed in chapters 2 and 3. Chapter 4 is devoted to the experimental study of the strong interaction between two tubes. Laser Doppler velocity measurements in the wakes close to cylinders and pressure measurements performed on tube walls are reported in this chapter. In chapter 5, a 2-D numerical simulation of two typical cases of interaction (Re = 1000 and Re = 5000) is performed. In the last chapter, a more complex application of strong interactions inside and downstream of a bunch of staggered tubes is analyzed experimentally for equivalent Reynolds regimes. (J.S.)
Bogodaev, N. V.; Zozulya, A. A.; Ivleva, Lyudmila I.; Korshunov, A. S.; Mamaev, A. V.; Polozkov, N. M.
1992-05-01
Most photorefractive crystals suitable for four-wave systems of phase self-conjugation and mutual conjugation have a fairly high level of light-induced scattering (fanning). This may imply that the nonlinearity of a crystal is too strong for optimal operation and a reduction in this nonlinearity would improve the characteristics. This statement is illustrated theoretically and experimentally using the geometry of a loop parametric oscillator as an example.
International Nuclear Information System (INIS)
Flambaum, V.V.; Shuryak, E.V.
2002-01-01
Recent data on the cosmological variation of the electromagnetic fine structure constant from distant quasar (QSO) absorption spectra have inspired a more general discussion of the possible variation of other constants. We discuss the variation of strong scale and quark masses. We derive limits on their relative change from (i) primordial big bang nucleosynthesis, (ii) the Oklo natural nuclear reactor, (iii) quasar absorption spectra, and (iv) laboratory measurements of hyperfine intervals
Electron dynamics during substorm dipolarization in Mercury's magnetosphere
Directory of Open Access Journals (Sweden)
D. C. Delcourt
2005-11-01
Full Text Available We examine the nonlinear dynamics of electrons during the expansion phase of substorms at Mercury using test particle simulations. A simple model of magnetic field line dipolarization is designed by rescaling a magnetic field model of the Earth's magnetosphere. The results of the simulations demonstrate that electrons may be subjected to significant energization on the time scale (several seconds of the magnetic field reconfiguration. In a similar manner to ions in the near-Earth's magnetosphere, it is shown that low-energy (up to several tens of eV electrons may not conserve the second adiabatic invariant during dipolarization, which leads to clusters of bouncing particles in the innermost magnetotail. On the other hand, it is found that, because of the stretching of the magnetic field lines, high-energy electrons (several keVs and above do not behave adiabatically and possibly experience meandering (Speiser-type motion around the midplane. We show that dipolarization of the magnetic field lines may be responsible for significant, though transient, (a few seconds precipitation of energetic (several keVs electrons onto the planet's surface. Prominent injections of energetic trapped electrons toward the planet are also obtained as a result of dipolarization. These injections, however, do not exhibit short-lived temporal modulations, as observed by Mariner-10, which thus appear to follow from a different mechanism than a simple convection surge.
Mechanism and regioselectivity of 1,3-dipolar cycloaddition ...
Indian Academy of Sciences (India)
The present analysis reveals that the cycloaddition reactions under study can be ... 1,3-Dipolar cycloaddition; sulphur-centred 1,3-dipoles; regioselectivity; DFT reactivity indices;. FMO theory. 1. Introduction. Five-membered heterocyclic compounds can be gene- rated by addition of a 1,3-dipole to a dipolarophile under.
AUTHOR|(INSPIRE)INSPIRE-00508100
The strong interaction is one of the four fundamental forces of nature. It binds together quarks inside protons and neutrons (which are example of baryons - particles composed of three quarks) and assures the stability of the atomic nucleus. Parameters describing the strong potential are also crucial for the neutron stars models used in astrophysics. What is more, a precise study of strongly interacting particles may help to better understand the process of baryon annihilation. The current knowledge of the strong interactions between baryons other than nucle- ons is limited - there exist only a few measurements of the cross sections for pairs of (anti)baryons. The reason is that in many cases it is not possible to perform scattering experiments with beams of particles and antiparticles, as the exotic matter (such as Λ, Ξ or Σ baryons) is very shot-living. This issue can be solved thanks to the recent particle colliders like the Large Hadron Collider and experiments dedicated to study the heavy-ion collisio...
Directory of Open Access Journals (Sweden)
Kawasaki Masahiro
2012-02-01
Full Text Available The plateau of 7Li abundance as a function of the iron abundance by spectroscopic observations of metal-poor halo stars (MPHSs indicates its primordial origin. The observed abundance levels are about a factor of three smaller than the primordial 7Li abundance predicted in the standard Big Bang Nucleosynthesis (BBN model. This discrepancy might originate from exotic particle and nuclear processes operating in BBN epoch. Some particle models include heavy (m >> 1 GeV long-lived colored particles which would be confined inside exotic heavy hadrons, i.e., strongly interacting massive particles (SIMPs. We have found reactions which destroy 7Be and 7Li during BBN in the scenario of BBN catalyzed by a long-lived sub-strongly interacting massive particle (sub-SIMP, X. The reactions are non radiative X captures of 7 Be and 7Li which can be operative if the X particle interacts with nuclei strongly enough to drive 7 Be destruction but not strongly enough to form a bound state with 4 He of relative angular momentum L = 1. We suggest that 7Li problem can be solved as a result of a new process beyond the standard model through which the observable signature was left on the primordial Li abundance.
Directory of Open Access Journals (Sweden)
Finkelstein Alexei V
2007-07-01
Full Text Available Abstract Background The prediction of ligand binding or protein structure requires very accurate force field potentials – even small errors in force field potentials can make a 'wrong' structure (from the billions possible more stable than the single, 'correct' one. However, despite huge efforts to optimize them, currently-used all-atom force fields are still not able, in a vast majority of cases, even to keep a protein molecule in its native conformation in the course of molecular dynamics simulations or to bring an approximate, homology-based model of protein structure closer to its native conformation. Results A strict analysis shows that a specific coupling of multi-atom Van der Waals interactions with covalent bonding can, in extreme cases, increase (or decrease the interaction energy by about 20–40% at certain angles between the direction of interaction and the covalent bond. It is also shown that on average multi-body effects decrease the total Van der Waals energy in proportion to the square root of the electronic component of dielectric permittivity corresponding to dipole-dipole interactions at small distances, where Van der Waals interactions take place. Conclusion The study shows that currently-ignored multi-atom Van der Waals interactions can, in certain instances, lead to significant energy effects, comparable to those caused by the replacement of atoms (for instance, C by N in conventional pairwise Van der Waals interactions.
International Nuclear Information System (INIS)
Son, Minho; Urbano, Alfredo
2016-01-01
We interpret the recently observed excess in the diphoton invariant mass as a new spin-0 resonant particle. On theoretical grounds, an interesting question is whether this new scalar resonance belongs to a strongly coupled sector or a well-defined weakly coupled theory. A possible UV-completion that has been widely considered in literature is based on the existence of new vector-like fermions whose loop contributions — Yukawa-coupled to the new resonance — explain the observed signal rate. The large total width preliminarily suggested by data seems to favor a large Yukawa coupling, at the border of a healthy perturbative definition. This potential problem can be fixed by introducing multiple vector-like fermions or large electric charges, bringing back the theory to a weakly coupled regime. However, this solution risks to be only a low-energy mirage: large multiplicity or electric charge can dangerously reintroduce the strong regime by modifying the renormalization group running of the dimensionless couplings. This issue is also tightly related to the (in)stability of the scalar potential. First, we study — in the theoretical setup described above — the parametric behavior of the diphoton signal rate, total width, and one-loop β functions. Then, we numerically solve the renormalization group equations, taking into account the observed diphoton signal rate and total width, to investigate the fate of the weakly coupled theory. We find that — with the only exception of few fine-tuned directions — weakly coupled interpretations of the excess are brought back to a strongly coupled regime if the running is taken into account.
Energy Technology Data Exchange (ETDEWEB)
Treiner, C. (Universite Pierre et Marie Curie, Paris (France)); Nortz, M.; Vaution, C. (Faculte de Pharmacie de Paris-sud, Chatenay-Malabry (France))
1990-07-01
The apparent partition coefficient P of barbituric acids between micelles and water has been determined in mixed binary surfactant solutions from solubility measurements in the whole micellar composition range. The binary systems chosen ranged from the strongly interacting system dodecyltrimethylammonium chloride + sodium dodecyl sulfate to weakly interacting systems such as benzyldimethyltetradecylammonium chloride + tetradecyltrimethyammonium chloride. In all cases studied, mixed micelle formation is unfavorable to micellar solubilization. A correlation is found between the unlike surfactants interaction energy, as measured by the regular solution parameter {beta} and the solute partition coefficient change upon surfactant mixing. By use of literature data on micellar solubilization in binary surfactant solutions, it is shown that the change of P for solutes which are solubilized by surface adsorption is generally governed by the sign and amplitude of the interaction parameter {beta}.
Supra Arcade Downflows with XRT Informed by Dipolarization Fronts with THEMIS
Kobelski, Adam; Savage, Sabrina L.; Malaspina, David M.
2016-01-01
Magnetic reconnection can rapidly reconfigure the magnetic field of the corona, accelerating plasma through the site of reconnection. Ambiguities due to the nature of remote sensing have complicated the interpretation of observations of the inflowing and outflowing plasma in reconnecting regions. In particular, the interpretation of sunward moving density depletions above flare arcades (known as Supra Arcade Downflows - SADs) is still debated. Hinode/XRT has provided a wealth of observations for SADs and helped inform our current understanding of these structures. SADs have been interpreted as wakes behind newly reconnected and outflowing loops (Supra Arcade Downflowing Loops - SADLs). Models have shown the plausibility of this interpretation, though this interpretation has not yet been fully accepted. We present here observations of newly reconnected outflowing loops observed via in situ instruments in the magnetosphere. These observations, provided by five THEMIS spacecraft, show that around retracting loops (dipolarization fronts in this context) similar dynamic temperature and density structures are found as seen in SADs. We compare data from multiple SADs and dipolarization fronts to show that the observational signatures implied in the corona can be directly observed in similar plasma regimes in the magnetosphere, strongly favoring the interpretation of SADs as wakes behind retracting loops.
Strong Cation···π Interactions Promote the Capture of Metal Ions within Metal-Seamed Nanocapsule
2015-01-01
Thallium ions are transported to the interior of gallium-seamed pyrogallol[4]arene nanocapsules. In comparison to the capture of Cs ions, the extent of which depends on the type and position of the anion employed in the cesium salt, the enhanced strength of Tl···π vs Cs···π interactions facilitates permanent entrapment of Tl+ ions on the capsule interior. “Stitching-up” the capsule seam with a tertiary metal (Zn, Rb, or K) affords new trimetallic nanocapsules in solid state. PMID:25405777
Czech Academy of Sciences Publication Activity Database
Borunda, M.F.; Liu, X.; Kovalev, A.A.; Liu, X.-J.; Jungwirth, Tomáš; Sinova, J.
2008-01-01
Roč. 78, č. 24 (2008), 245315/1-245315/9 ISSN 1098-0121 R&D Projects: GA MŠk LC510; GA AV ČR KAN400100652; GA ČR GEFON/06/E002 EU Projects: European Commission(XE) 015728 - NANOSPIN Institutional research plan: CEZ:AV0Z10100521 Keywords : Aharonov-Casher effect * spin Hall effect * spin-orbit interaction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.322, year: 2008
Jiang, Yuzhu; He, Peng; Guan, Xi-Wen
2016-01-01
It was shown [Chin. Phys. Lett. 28, 020503 (2011)] that at zero temperature the ground state of the one-dimensional (1D) $w$-component Fermi gas coincides with that of the spinless Bose gas in the limit $\\omega\\to \\infty$. This behaviour was experimentally evidenced through a quasi-1D tightly trapping ultracold ${}^{173}$Yb atoms in the recent paper [Nature Physics 10, 198 (2014)]. However, understanding of low temperature behaviour of the Fermi gases with a repulsive interaction acquires spi...
A Test of the Flavor Independence of Strong Interactions in e+e- Annihilation at the Z0 Pole
Energy Technology Data Exchange (ETDEWEB)
Muller, David
1999-09-03
This thesis presents a comparison of the strong coupling of the gluons to light (q_{l} = u + d + s), c, and b quarks, determined from multijet rates in flavor-tagged samples of approximately 150,000 hadronic Z^{0} decays recorded with the SLC Large Detector at the SLAC Linear Collider between 1993 and 1995. Flavor separation among primary q_{l} {anti q_{l}} , c{anti c} and b {anti b} final states was made on the basis of the reconstructed mass of long-lived heavy-hadron decay vertices, yielding tags with high purity and low bias against {>=} 3-jet final states. The data obtained imply no flavor dependence within our sensitivity.
International Nuclear Information System (INIS)
Gregori, G.; Hansen, S.B.; Key, M.H.; King, J.; Mackinnon, A.J.; Park, H.; Patel, P.K.; Shepard, R.; Snavely, R.A.; Wilks, S.C.; Glenzer, S.H.
2005-01-01
We have measured high resolution copper Kα spectra from a picosecond high intensity laser produced plasma. By fitting the shape of the experimental spectra with a self-consistent-field model which includes all the relevant line shifts from multiply ionized atoms, we are able to infer time and spatially averaged electron temperatures (T e ) and ionization state (Z) in the foil. Our results show increasing values for T e and Z when the overall mass of the target is reduced. In particular, we measure temperatures in excess of 200 eV with Z ∼ 13-14. For these conditions the ion-ion coupling constant is Λ ii ∼ 8-9, thus suggesting the achievement of a strongly coupled plasma regime
Vafek, Oskar; Chubukov, Andrey V.
2017-02-01
We present a novel mechanism of s -wave pairing in Fe-based superconductors. The mechanism involves holes near dx z/dy z pockets only and is applicable primarily to strongly hole doped materials. We argue that as long as the renormalized Hund's coupling J exceeds the renormalized interorbital Hubbard repulsion U', any finite spin-orbit coupling gives rise to s -wave superconductivity. This holds even at weak coupling and regardless of the strength of the intraorbital Hubbard repulsion U . The transition temperature grows as the hole density decreases. The pairing gaps are fourfold symmetric, but anisotropic, with the possibility of eight accidental nodes along the larger pocket. The resulting state is consistent with the experiments on KFe2 As2 .
International Nuclear Information System (INIS)
Olaniyi, B.; Shor, A.; Cheng, S.C.; Dugan, G.; Wu, C.S.
1981-05-01
The effective quadrupole moments Q sub(eff) of the nuclei of 165 Ho, 175 Lu, 176 Lu, 179 Hf and 181 Ta were accurately measured by detecting the pionic atom 5g-4f x-rays of the elements. The spectroscopic quadrupole moments, Q sub(spec), were obtained by correcting Q sub(eff) for nuclear finite size effect, distortion of the pion wave function by the pion-nucleus strong interaction, and contribution to the energy level splittings by the strong interaction. The intrinsic quadrupole moments, Q 0 , were obtained by projecting Q sub(spec) into the frame of reference fixed on the nucleus. The shift, epsilon 0 , and broadening, GAMMA 0 , of the 4f energy level due to the strong interactions between the pion and the nucleons for all the elements were also measured. Theoretical values of epsilon 0 and GAMMA 0 were calculated and compared to the experimental values. The measured values of Q 0 were compared with the existing results in muonic and pionic atoms. The measured values of epsilon 0 and GAMMA 0 were also compared with existing values. (auth)
Wang, Jun; Apte, Pankaj A; Morris, James R; Zeng, Xiao Cheng
2013-09-21
Stockmayer fluids are a prototype model system for dipolar fluids. We have computed the freezing temperatures of Stockmayer fluids at zero pressure using three different molecular-dynamics simulation methods, namely, the superheating-undercooling method, the constant-pressure and constant-temperature two-phase coexistence method, and the constant-pressure and constant-enthalpy two-phase coexistence method. The best estimate of the freezing temperature (in reduced unit) for the Stockmayer (SM) fluid with the dimensionless dipole moment μ*=1, √2, √3 is 0.656 ± 0.001, 0.726 ± 0.002, and 0.835 ± 0.005, respectively. The freezing temperature increases with the dipolar strength. Moreover, for the first time, the solid-liquid interfacial free energies γ of the fcc (111), (110), and (100) interfaces are computed using two independent methods, namely, the cleaving-wall method and the interfacial fluctuation method. Both methods predict that the interfacial free energy increases with the dipole moment. Although the interfacial fluctuation method suggests a weaker interfacial anisotropy, particularly for strongly dipolar SM fluids, both methods predicted the same trend of interfacial anisotropy, i.e., γ100 > γ110 > γ111.
Halverson, Tom; Iouchtchenko, Dmitri; Roy, Pierre-Nicholas
2018-02-01
We propose a variational approach for the calculation of the quantum entanglement entropy of assemblies of rotating dipolar molecules. A basis truncation scheme based on the total angular momentum quantum number is proposed. The method is tested on hydrogen fluoride (HF) molecules confined in C60 fullerene cages themselves trapped in a nanotube to form a carbon peapod. The rotational degrees of freedom of the HF molecules and dipolar interactions between neighboring molecules are considered in our model Hamiltonian. Both screened and unscreened dipoles are simulated and results are obtained for the ground state and one excited state that is expected to be accessible via a far-infrared collective excitation. The effect of basis truncation on energetic and entanglement properties is examined and discussed in terms of size extensivity. It is empirically found that for unscreened dipoles, a total angular momentum cutoff that increases linearly with the number of rotors is required in order to obtain proper system size scaling of the chemical potential and entanglement entropy. Recent experiments [A. Krachmalnicoff et al., Nat. Chem. 8, 953 (2016)] suggest substantial screening of the HF dipole moment, so much smaller basis sets are required to obtain converged results in this realistic case. Static correlation functions are also computed and are shown to decay much quicker in the case of screened dipoles. Our variational results are also used to test the accuracy of perturbative and pairwise ansatz treatments.
Butter, K; Frederik, P M; Vroege, G J; Philipse, A P
2003-01-01
The particle structure of ferrofluids is studied in situ, by cryogenic electron microscopy, on vitrified films of iron and magnetite dispersions. By means of synthesis of iron colloids with controlled particle size and different types of surfactant, dipolar particle interactions can be varied over a broad range, which significantly influences the ferrofluid particle structure. Our experiments on iron dispersions (in contrast to magnetite dispersions) for the first time demonstrate, in ferrofluids in zero field, a transition with increasing particle size from separate particles to linear chains of particles (Butter K, Bomans P H, Frederik P M, Vroege G J and Philipse A P 2003 Nature Mater. 2 88). These chains, already predicted theoretically by de Gennes and Pincus (de Gennes P G and Pincus P A 1970 Phys. Kondens. Mater. 11 189), very much resemble the fluctuating chains found in simulations of dipolar fluids (Weis J J 1998 Mol. Phys. 93 361, Chantrell R W, Bradbury A, Popplewell J and Charles S W 1982 J. Appl...
Disentangling weak and strong interactions in B → K*(→ Kπ)π Dalitz-plot analyses
Energy Technology Data Exchange (ETDEWEB)
Charles, Jerome [CNRS, Aix-Marseille Univ., Universite de Toulon, CPT UMR 7332, Marseille (France); Descotes-Genon, Sebastien [CNRS, Univ. Paris-Sud, Universite Paris-Saclay, Laboratoire de Physique Theorique (UMR 8627), Orsay (France); Ocariz, Jose [Sorbonne Universites, UPMC Univ. Paris 06, UMR 7585, LPNHE, Paris (France); Universite Paris Diderot, LPNHE UMR 7585, Sorbonne Paris Cite, Paris (France); Perez Perez, Alejandro [Universite de Strasbourg, CNRS, IPHC UMR 7178, Strasbourg (France); Collaboration: For the CKMfitter Group
2017-08-15
Dalitz-plot analyses of B → Kππ decays provide direct access to decay amplitudes, and thereby weak and strong phases can be disentangled by resolving the interference patterns in phase space between intermediate resonant states. A phenomenological isospin analysis of B → K*(→ Kπ)π decay amplitudes is presented exploiting available amplitude analyses performed at the BaBar, Belle and LHCb experiments. A first application consists in constraining the CKM parameters thanks to an external hadronic input. A method, proposed some time ago by two different groups and relying on a bound on the electroweak penguin contribution, is shown to lack the desired robustness and accuracy, and we propose a more alluring alternative using a bound on the annihilation contribution. A second application consists in extracting information on hadronic amplitudes assuming the values of the CKM parameters from a global fit to quark flavour data. The current data yields several solutions, which do not fully support the hierarchy of hadronic amplitudes usually expected from theoretical arguments (colour suppression, suppression of electroweak penguins), as illustrated from computations within QCD factorisation. Some prospects concerning the impact of future measurements at LHCb and Belle II are also presented. Results are obtained with the CKMfitter analysis package, featuring the frequentist statistical approach and using the Rfit scheme to handle theoretical uncertainties. (orig.)
Strečka, Jozef
2018-01-01
The mixed spin-1/2 and spin-S Ising model on the Union Jack (centered square) lattice with four different three-spin (triplet) interactions and the uniaxial single-ion anisotropy is exactly solved by establishing a rigorous mapping equivalence with the corresponding zero-field (symmetric) eight-vertex model on a dual square lattice. A rigorous proof of the aforementioned exact mapping equivalence is provided by two independent approaches exploiting either a graph-theoretical or spin representation of the zero-field eight-vertex model. An influence of the interaction anisotropy as well as the uniaxial single-ion anisotropy on phase transitions and critical phenomena is examined in particular. It is shown that the considered model exhibits a strong-universal critical behaviour with constant critical exponents when considering the isotropic model with four equal triplet interactions or the anisotropic model with one triplet interaction differing from the other three. The anisotropic models with two different triplet interactions, which are pairwise equal to each other, contrarily exhibit a weak-universal critical behaviour with critical exponents continuously varying with a relative strength of the triplet interactions as well as the uniaxial single-ion anisotropy. It is evidenced that the variations of critical exponents of the mixed-spin Ising models with the integer-valued spins S differ basically from their counterparts with the half-odd-integer spins S.
SN 2011A: A Low-luminosity Interacting Transient with a Double Plateau and Strong Sodium Absorption
de Jaeger, T.; Anderson, J. P.; Pignata, G.; Hamuy, M.; Kankare, E.; Stritzinger, M. D.; Benetti, S.; Bufano, F.; Elias-Rosa, N.; Folatelli, G.; Förster, F.; González-Gaitán, S.; Gutiérrez, C. P.; Inserra, C.; Kotak, R.; Lira, P.; Morrell, N.; Taddia, F.; Tomasella, L.
2015-07-01
We present optical photometry and spectroscopy of the optical transient SN 2011A. Our data span 140 days after discovery including {BVRI} u\\prime g\\prime r\\prime i\\prime z\\prime photometry and 11 epochs of optical spectroscopy. Originally classified as a type IIn supernova (SN IIn) due to the presence of narrow Hα emission, this object shows exceptional characteristics. First, the light curve shows a double plateau, a property only observed before in the impostor SN 1997bs. Second, SN 2011A has a very low luminosity ({M}V=-15.72), placing it between normal luminous SNe IIn and SN impostors. Third, SN 2011A shows low velocity and high equivalent width absorption close to the sodium doublet, which increases with time and is most likely of circumstellar origin. This evolution is also accompanied by a change in line profile; when the absorption becomes stronger, a P Cygni profile appears. We discuss SN 2011A in the context of interacting SNe IIn and SN impostors, which appears to confirm the uniqueness of this transient. While we favor an impostor origin for SN 2011A, we highlight the difficulty in differentiating between terminal and non-terminal interacting transients. This paper includes data obtained with the 6.5 m Magellan Telescopes and du Pont telescope; the Gemini-North Telescope, Mauna Kea, USA (Gemini Program GN-2010B-Q67, PI: Stritzinger); the PROMPT telescopes at Cerro Tololo Inter-American Observatory in Chile; with the Liverpool Telescope operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias with financial support from the UK Science and Technology Facilities Council; based on observations made with the Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias; the NTT from ESO Science Archive
International Nuclear Information System (INIS)
Konorov, S. O.; Hepburn, J. W.; Milner, V.
2011-01-01
Understanding the effect of strong laser pulses on the evolution of an atomic or molecular wave function is important in the context of coherent control in the strong-field regime, when power broadening and dynamic Stark shifts become comparable with or bigger than the bandwidth of the control field. We experimentally demonstrate the method of complete characterization of a complex-valued amplitude of a quantum state driven by a strong two-photon field. The method is based on coherent scattering of a weak probe pulse from the strong-field-induced atomic coherence, followed by the detection of the time- and frequency-resolved parametric four-wave-mixing signal. We show that the proposed technique corresponds to a cross-correlation frequency-resolved optical gating (XFROG) of the highly perturbed evolution of an atomic quantum state. Utilizing the XFROG retrieval algorithm, we determine both the amplitude and phase of an atomic wave function at any time moment throughout the interaction with the driving field. The direct retrieval of the time-dependent phase of the wave function, rather than the population dynamics only, enables us to observe the strong-field effects with arbitrary time and frequency resolution.
Rybczynski, Maciej; Baatar, B.; Barna, D.; Bartke, J.; Beck, H.; Betev, L.; Bialkowska, H.; Blume, C.; Bogusz, M.; Boimska, B.; Book, J.; Botje, M.; Buncic, P.; Cetner, T.; Christakoglou, P.; Chung, P.; Chvala, O.; Cramer, J.G.; Eckardt, V.; Fodor, Z.; Foka, P.; Friese, V.; Gazdzicki, M.; Grebieszkow, K.; Hohne, C.; Kadija, K.; Karev, A.; Kolesnikov, V.I.; Kowalski, M.; Kresan, D.; Laszlo, A.; Lacey, R.; van Leeuwen, M.; Mackowiak-Pawlowska, M.; Makariev, M.; Malakhov, A.I.; Mateev, M.; Melkumov, G.L.; Mitrovski, M.; Mrowczynski, St.; Nicolic, V.; Palla, G.; Panagiotou, A.D.; Peryt, W.; Pluta, J.; Prindle, D.; Puhlhofer, F.; Renfordt, R.; Roland, C.; Roland, G.; Rybczynski, M.; Rybicki, A.; Sandoval, A.; Schmitz, N.; Schuster, T.; Seyboth, P.; Sikler, F.; Skrzypczak, E.; Slodkowski, M.; Stefanek, G.; Stock, R.; Strobele, H.; Susa, T.; Szuba, M.; Utvic, M.; Varga, D.; Vassiliou, M.; Veres, G.I.; Vesztergombi, G.; Vranic, D.; Wlodarczyk, Z.; Wojtaszek-Szwarc, A.
2013-01-01
The exploration of the QCD phase diagram particularly the search for a phase transition from hadronic to partonic degrees of freedom and possibly a critical endpoint, is one of the most challenging tasks in present heavy-ion physics. As observed by the NA49 experiment, several hadronic observables in central Pb+Pb collisions at the CERN SPS show qualitative changes in their energy dependence. These features are not observed in elementary interactions and indicate the onset of a phase transition in the SPS energy range. The existence of a critical point is expected to result in the increase of event-by-event fluctuations of various hadronic observables provided that the freeze-out of the measured hadrons occurs close to its location in the phase diagram and the evolution of the final hadron phase does not erase the fluctuations signals. A selection of NA49 results on di-pion and proton intermittency from the scan of the phase diagram will be discussed.
Rybczyński, Maciej
2014-01-01
The exploration of the QCD phase diagram particularly the search for a phase transition from hadronic to partonic degrees of freedom and possibly a critical endpoint, is one of the most challenging tasks in present heavy-ion physics. As observed by the NA49 experiment, several hadronic observables in central Pb+Pb collisions at the CERN SPS show qualitative changes in their energy dependence. These features are not observed in elementary interactions and indi- cate the onset of a phase transition in the SPS energy range. The existence of a critical point is expected to result in the increase of event-by-event fluctuations of various hadronic observables provided that the freeze-out of the measured hadrons occurs close to its location in the phase di- agram and the evolution of the final hadron phase does not erase the fluctuations signals. Further information about the existence and nature of a phase transition in the SPS energy range can be gained from the studies of event-by-event fluctuations of final stat...
Carleo, Giuseppe; Cevolani, Lorenzo; Sanchez-Palencia, Laurent; Holzmann, Markus
2017-07-01
We introduce the time-dependent variational Monte Carlo method for continuous-space Bose gases. Our approach is based on the systematic expansion of the many-body wave function in terms of multibody correlations and is essentially exact up to adaptive truncation. The method is benchmarked by comparison to an exact Bethe ansatz or existing numerical results for the integrable Lieb-Liniger model. We first show that the many-body wave function achieves high precision for ground-state properties, including energy and first-order as well as second-order correlation functions. Then, we study the out-of-equilibrium, unitary dynamics induced by a quantum quench in the interaction strength. Our time-dependent variational Monte Carlo results are benchmarked by comparison to exact Bethe ansatz results available for a small number of particles, and are also compared to quench action results available for noninteracting initial states. Moreover, our approach allows us to study large particle numbers and general quench protocols, previously inaccessible beyond the mean-field level. Our results suggest that it is possible to find correlated initial states for which the long-term dynamics of local density fluctuations is close to the predictions of a simple Boltzmann ensemble.
Rączka, P.; Dubois, J.-L.; Hulin, S.; Tikhonchuk, V.; Rosiński, M.; Zaraś-Szydłowska, A.; Badziak, J.
2017-12-01
Measurements are reported of the target neutralization current, the target charge, and the tangential component of the magnetic field generated as a result of laser-target interaction by pulses with the energy in the range of 45 mJ to 92 mJ on target and the pulse duration from 39 fs to 1000 fs. The experiment was performed at the Eclipse facility in CELIA, Bordeaux. The aim of the experiment was to extend investigations performed for the thick (mm scale) targets to the case of thin (micrometer thickness) targets in a way that would allow for a straightforward comparison of the results. We found that thin foil targets tend to generate 20 to 50 percent higher neutralization current and the target charge than the thick targets. The measurement of the tangential component of the magnetic field had shown that the initial spike is dominated by the 1 ns pulse consistent with the 1 ns pulse of the neutralization current, but there are some differences between targets of different type on sub-ns scale, which is an effect going beyond a simple picture of the target acting as an antenna. The sub-ns structure appears to be reproducible to surprising degree. We found that there is in general a linear correlation between the maximum value of the magnetic field and the maximum neutralization current, which supports the target-antenna picture, except for pulses hundreds of fs long.
Östman, Erik; Arnalds, Unnar; Kapaklis, Vassilios; Hjörvarsson, Björgvin
2015-09-01
For a small island of a magnetic material the magnetic state of the island is mainly determined by the exchange interaction and the shape anisotropy. Two or more islands placed in close proximity will interact through dipolar interactions. The state of a large system will thus be dictated by interactions at both these length scales. Enabling internal thermal fluctuations, e.g. by the choice of material, of the individual islands allows for the study of thermal ordering in extended nano-patterned magnetic arrays [1,2]. As a result nano-magnetic arrays represent an ideal playground for the study of physical model systems. Here we present three different studies all having used magneto-optical imaging techniques to observe, in real space, the order of the systems. The first study is done on a square lattice of circular islands. The remanent magnetic state of each island is a magnetic vortex structure and we can study the temperature dependence of the vortex nucleation and annihilation fields [3]. The second are long chains of dipolar coupled elongated islands where the magnetization direction in each island only can point in one of two possible directions. This creates a system which in many ways mimics the Ising model [4] and we can relate the correlation length to the temperature. The third one is a spin ice system where elongated islands are placed in a square lattice. Thermal excitations in such systems resemble magnetic monopoles [2] and we can investigate their properties as a function of temperature and lattice parameters. [1] V. Kapaklis et al., New J. Phys. 14, 035009 (2012) [2] V. Kapaklis et al., Nature Nanotech 9, 514(2014) [3] E. Östman et al.,New J. Phys. 16, 053002 (2014) [4] E. Östman et al.,Thermal ordering in mesoscopic Ising chains, In manuscript.
International Nuclear Information System (INIS)
Lu Dawei; Peng Xinhua; Du Jiangfeng; Zhu Jing; Zou Ping; Yu Yihua; Zhang Shanmin; Chen Qun
2010-01-01
An important quantum search algorithm based on the quantum random walk performs an oracle search on a database of N items with O(√(phN)) calls, yielding a speedup similar to the Grover quantum search algorithm. The algorithm was implemented on a quantum information processor of three-qubit liquid-crystal nuclear magnetic resonance (NMR) in the case of finding 1 out of 4, and the diagonal elements' tomography of all the final density matrices was completed with comprehensible one-dimensional NMR spectra. The experimental results agree well with the theoretical predictions.
Charged perfect fluid tori in strong central gravitational and dipolar magnetic fields
Czech Academy of Sciences Publication Activity Database
Kovář, J.; Slaný, P.; Cremaschini, C.; Stuchlík, Z.; Karas, Vladimír; Trova, Audrey
2016-01-01
Roč. 93, June (2016), 124055/1-124055/20 ISSN 1550-7998 R&D Projects: GA ČR GB14-37086G; GA MŠk(CZ) LH14049 Grant - others:GA ČR(CZ) GP14-07753P Institutional support: RVO:67985815 Keywords : black holes * accretion discscretion discs Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.643, year: 2014
Energy Technology Data Exchange (ETDEWEB)
Alcaraz, Francisco Castilho
1977-07-01
Using the propagator's technique in the grand ensemble developed by Montroll and Ward we investigate the magnetic properties of an interacting electron gas in a strong magnetic field. The free propagator properly constructed shows that the spin paramagnetism does not have a term with strong temperature dependence, contrary to the result of Isihara. Considering the electron density to be constant, the dHVA oscillations in the magnetic susceptibility and sound velocity, considering the effects of first exchange interactions, show only one phase in agreement with experimental result, while Ichimura and Isihara obtained two phases differing by {pi}/2. The effects of first order exchange interactions in the dHVA oscillations of the magnetic susceptibility and sound velocity give rise to an exponential factor in the amplitudes of oscillator (Dingle factor), being the Dingle temperature linearly dependent of the Fermi velocity. The calculations of the ring diagram contribution to the grand partition function, show that the approximation used by Isihara for this calculations is not good and the dHVA oscillations of the contributions from the ring diagrams for the grand partition function have a phase differing by {pi}/2 from that obtained by Isihara. (author)
Cohen, I. J.; Mauk, B.; Anderson, B. J.; Sitnov, M. I.; Motoba, T.; Ohtani, S.; Gkioulidou, M.; Fuselier, S. A.; Giles, B. L.; Strangeway, R. J.; Torbert, R. B.; Burch, J. L.
2017-12-01
Observations from the Energetic Ion Spectrometer (EIS) instruments aboard MMS have shown angular (pitch, elevation, azimuthal) asymmetries of energetic (>10s of keV) ions corresponding to dipolarization events in the near-Earth and distant magnetotail. In particular, EIS distinguishes the species composition of these ions (protons, helium, oxygen) and reveals apparent species-based differences in their response. This study presents analysis of the dynamic injection and mass-dependent response of energetic ions that likely result from the kinetic response of the ions to the time-varying electric and magnetic fields associated with injection process. Analysis is focused on discriminating between truly kinetic responses to the dynamics and the features that arise from large gyro-radii particles in the vicinity of strong spatial gradients. The study will focus on EIS measurements and include supplementary data from the FIELDS, FPI, and HPCA instruments.
Poh, G.; Slavin, J. A.; Lu, S.; Le, G.; Cassak, P.; Eastwood, J. P.; Ozturk, D. S.; Zou, S.; Nakamura, R.; Baumjohann, W.; Russell, C. T.; Gershman, D. J.; Giles, B. L.; Pollock, C.; Moore, T. E.; Torbert, R. B.; Burch, J. L.
2017-12-01
The formation of flux ropes is thought to be an integral part of the process that may have important consequences for the onset and subsequent rate of reconnection in the tail. Earthward flows, i.e. bursty bulk flows (BBFs), generate dipolarization fronts (DFs) as they interact with the closed magnetic flux in their path. Global hybrid simulations and THEMIS observations have shown that earthward-moving flux ropes can undergo magnetic reconnection with the near-Earth dipole field in the downtail region between the Near Earth Neutral Line and the near-Earth dipole field to create DFs-like signatures. In this study, we analyzed sequential "chains" of earthward-moving, ion-scale flux ropes embedded within DFs observed during MMS first tail season. MMS high-resolution plasma measurements indicate that these earthward flux ropes embedded in DFs have a mean bulk flow velocity and diameter of 250 km/s and 1000 km ( 2‒3 ion inertial length λi), respectively. Magnetic reconnection signatures preceding the flux rope/DF encounter were also observed. As the southward-pointing magnetic field in the leading edge of the flux rope reconnects with the northward-pointing geomagnetic field, the characteristic quadrupolar Hall magnetic field in the ion diffusion region and electron outflow jets in the north-south direction are observed. Our results strongly suggest that the earthward moving flux ropes brake and gradually dissipate due to magnetic reconnection with the near Earth magnetic field. We have also examined the occurrence rate of these dissipating flux ropes/DF events as a function of downtail distances.
Angelopoulos, Angelos; Backenstoss, Gerhard; Bargassa, P; Behnke, O; Benelli, A; Bertin, V; Blanc, F; Bloch, P; Carlson, P J; Carroll, M; Cawley, E; Chertok, M B; Danielsson, M; Dejardin, M; Derré, J; Ealet, A; Eleftheriadis, C; Fetscher, W; Fidecaro, Maria; Filipcic, A; Francis, D; Fry, J; Gabathuler, Erwin; Gamet, R; Gerber, H J; Go, A; Haselden, A; Haymen, P J; Henry-Coüannier, F; Hollander, R W; Jon-And, K; Kettle, P R; Kokkas, P; Kreuger, R; Le Gac, R; Leimgruber, F; Mandic, I; Manthos, N; Marel, Gérard; Mikuz, M; Miller, J; Montanet, François; Müller, A; Nakada, Tatsuya; Pagels, B; Papadopoulos, I M; Pavlopoulos, P; Polivka, G; Rickenbach, R; Roberts, B L; Ruf, T; Sakelliou, L; Schäfer, M; Schaller, L A; Schietinger, T; Schopper, A; Tauscher, Ludwig; Thibault, C; Touchard, F; Touramanis, C; van Eijk, C W E; Vlachos, S; Weber, P; Wigger, O; Wolter, M; Zavrtanik, D; Zimmerman, D
2001-01-01
The CPLEAR set-up (modified) has been used to determine the K/sub L/- K/sub S/ mass difference by a method where neutral-kaon strangeness oscillations are monitored through kaon strong interactions, rather than semileptonic decays, thus requiring no assumptions on CPT invariance for the decay amplitudes. The result, Delta m= (0.5343+or-0.0063/sub stat/+or-0.0025/sub syst/)*10/sup 10/ h(cross) /s, provides a valuable input for CPT tests. (22 refs).
Park, Sarah S; Hendon, Christopher H; Fielding, Alistair J; Walsh, Aron; O'Keeffe, Michael; Dincă, Mircea
2017-03-15
The structure-directing role of the inorganic secondary building unit (SBU) is key for determining the topology of metal-organic frameworks (MOFs). Here we show that organic building units relying on strong π interactions that are energetically competitive with the formation of common inorganic SBUs can also play a role in defining the topology. We demonstrate the importance of the organic SBU in the formation of Mg 2 H 6 (H 3 O)(TTFTB) 3 (MIT-25), a mesoporous MOF with the new ssp topology. A delocalized electronic hole is critical in the stabilization of the TTF triad organic SBUs and exemplifies a design principle for future MOF synthesis.
Directory of Open Access Journals (Sweden)
B BOUHAFS
2003-12-01
Full Text Available The attractive potential energy between the atoms of rubidium vapor and a dielectric wall has been investigated by monitoring the reflection light at the interface. The atom- wall interaction potential of the form V(z = - C /z3 (z: atom-wall allows to predict experimental results only for weak regime, i.e., where C<< 0.2 kHzmm3. In the strong interaction case, the dispersive line shape is turned into an absorption-type line shape. The influence of atomic density on the shift of the selective reflection resonance relatively to the frequency of unperturbed atomic transition is found to be red with a negative slope. This technique opens the way to characterize the windows made of different materials thin films.
International Nuclear Information System (INIS)
Kura, H; Takahashi, M; Ogawa, T
2011-01-01
High-volume fraction α-Fe nanoparticle (NP) agglomerates were prepared using chemically synthesized NPs. In the agglomerate, NPs are separated by surfactant and NP superlattice with a hexagonal close-packed structure is locally realized. Volume fractions of NPs at 20% and 42% were obtained in agglomerates consisting of 2.9 nm and 8.2 nm diameter NPs, respectively. The high saturation magnetization of α-Fe NPs and high volume fraction of NPs in the agglomerate provide strong magnetic dipole-dipole interaction. The interaction energy of the agglomerate became much larger than the anisotropic energy of individual NPs. As a result, the blocking temperature of the 8.2 nm NP agglomerate was significantly enhanced from 52.2 K to around 500 K. (fast track communication)
International Nuclear Information System (INIS)
Suzuki, Yohichi; Tanimura, Yoshitaka
2007-01-01
Electron transfer reaction in a polar solvent is modeled by a solute dipole surrounded by dipolar molecules with simple rotational dynamics posted on the three-dimensional distorted lattice sites. The interaction energy between the solute and solvent dipoles as a reaction coordinate is adopted and free energy landscapes are calculated by generating all possible states for a 26 dipolar system and by employing Wang-Landau sampling algorithm for a 92 dipolar system. For temperatures higher than the energy scale of dipole-dipole interactions, the free energy landscapes for the small reaction coordinate region have quadratic shape as predicted by Marcus [Rev. Mod. Phys. 65, 599 (1993)] whereas for the large reaction coordinate region, the landscapes exhibit a nonquadratic shape. When the temperature drops, small notched structures appear on the free energy profiles because of the frustrated interactions among dipoles. The formation of notched structure is analyzed with statistical approach and it is shown that the amplitude of notched structure depend upon the segment size of the reaction coordinate and is characterized by the interaction energy among the dipoles. Using simulated free energy landscapes, the authors calculate the reaction rates as a function of the energy gap for various temperatures. At high temperature, the reactions rates follow a bell shaped (inverted parabolic) energy gap law in the small energy gap regions, while it becomes steeper than the parabolic shape in a large energy gap regions due to the nonquadratic shape of the free energy landscape. The peak position of parabola also changes as the function of temperature. At low temperature, the profile of the reaction rates is no longer smooth because of the many local minima of the free energy landscape
van Zyl, B. P.; Zaremba, E.; Pisarski, P.
2013-04-01
We systematically develop a density functional description for the equilibrium properties of a two-dimensional, harmonically trapped, spin-polarized dipolar Fermi gas based on the Thomas-Fermi-von Weizsäcker approximation. We pay particular attention to the construction of the two-dimensional kinetic energy functional, where corrections beyond the local density approximation must be motivated with care. We also present an intuitive derivation of the interaction energy functional associated with the dipolar interactions and provide physical insight into why it can be represented as a local functional. Finally, a simple and highly efficient self-consistent numerical procedure is developed to determine the equilibrium density of the system for a range of dipole interaction strengths.
Propagation of Dipolarization Signatures Observed by the Van Allen Probes in the Inner Magnetosphere
Ohtani, S.; Motoba, T.; Gkioulidou, M.; Takahashi, K.; Kletzing, C.
2017-12-01
Dipolarization, the change of the local magnetic field from a stretched to a more dipolar configuration, is one of the most fundamental processes of magnetospheric physics. It is especially critical for the dynamics of the inner magnetosphere. The associated electric field accelerates ions and electrons and transports them closer to Earth. Such injected ions intensify the ring current, and electrons constitute the seed population of the radiation belt. Those ions and electrons may also excite various waves that play important roles in the enhancement and loss of the radiation belt electrons. Despite such critical consequences, the general characteristics of dipolarization in the inner magnetosphere still remain to be understood. The Van Allen Probes mission, which consists of two probes that orbit through the equatorial region of the inner magnetosphere, provides an ideal opportunity to examine dipolarization signatures in the core of the ring current. In the present study we investigate the spatial expansion of the dipolarization region by examining the correlation and time delay of dipolarization signatures observed by the two probes. Whereas in general it requires three-point measurements to deduce the propagation of a signal on a certain plane, we statically examined the observed time delays and found that dipolarization signatures tend to propagate radially inward as well as away from midnight. In this paper we address the propagation of dipolarization signatures quantitatively and compare with the propagation velocities reported previously based on observations made farther away from Earth. We also discuss how often and under what conditions the dipolarization region expands.
Beyond mean-field properties of binary dipolar Bose mixtures at low temperatures
Pastukhov, Volodymyr
2017-02-01
We rigorously analyze the low-temperature properties of homogeneous three-dimensional two-component Bose mixture with dipole-dipole interaction. For such a system the effective hydrodynamic action that governs the behavior of low-energy excitations is derived. The infrared structure of the exact single-particle Green's functions is obtained in terms of macroscopic parameters, namely the inverse compressibility and the superfluid density matrices. Within the one-loop approximation we calculate some of the most relevant observable quantities and give the beyond mean-field stability condition for the binary dipolar Bose gas in the dilute limit. A brief variational derivation of the coupled equations that describe macroscopic hydrodynamics of the system in the external nonuniform potential at zero temperature is presented.
Strongly interacting matter under rotation
Jiang, Yin; Lin, Zi-Wei; Huang, Xu-Guang; Liao, Jinfeng
2018-02-01
The vorticity-driven effects are systematically studied in various aspects. With AMPT the distributions of vorticity has been investigated in heavy ion collisions with different collision parameters. Taking the rotational polarization effect into account a generic condensate suppression mechanism is discussed and quantitatively studied with NJL model. And in chiral restored phase the chiral vortical effects would generate a new collective mode, i.e. the chiral vortical wave. Using the rotating quark-gluon plasma in heavy ion collisions as a concrete example, we show the formation of induced flavor quadrupole in QGP and estimate the elliptic flow splitting effect for Λ baryons.
Strongly interacting matter under rotation
Directory of Open Access Journals (Sweden)
Jiang Yin
2018-01-01
Full Text Available The vorticity-driven effects are systematically studied in various aspects. With AMPT the distributions of vorticity has been investigated in heavy ion collisions with different collision parameters. Taking the rotational polarization effect into account a generic condensate suppression mechanism is discussed and quantitatively studied with NJL model. And in chiral restored phase the chiral vortical effects would generate a new collective mode, i.e. the chiral vortical wave. Using the rotating quark-gluon plasma in heavy ion collisions as a concrete example, we show the formation of induced flavor quadrupole in QGP and estimate the elliptic flow splitting effect for Λ baryons.
Strong interaction at finite temperature
Indian Academy of Sciences (India)
Saha Institute of Nuclear Physics, 1/AF, Bidhan Nagar, Kolkata 700 064, India. Abstract. We review two ... tem, from which its energy density, pressure etc. can be obtained. But to describe the heavy-ion ... quantity follows the same steps as for its vacuum counterpart, with the replacement of free vacuum propagators by free ...
Strong interaction at finite temperature
Indian Academy of Sciences (India)
The ﬁrst one is the general method of chiral perturbation theory, which may be readily applied to this problem. The other is the method of thermal QCD sum rules. We show that, when the spectral sides of the sum rules are calculated correctly, they do not lead to any new results, but reproduce those of the vacuum sum rules.
Li, Siwei; Xu, Yao; Chen, Yifu; Li, Weizhen; Lin, Lili; Li, Mengzhu; Deng, Yuchen; Wang, Xiaoping; Ge, Binghui; Yang, Ce; Yao, Siyu; Xie, Jinglin; Li, Yongwang; Liu, Xi; Ma, Ding
2017-08-28
A one-step ligand-free method based on an adsorption-precipitation process was developed to fabricate iridium/cerium oxide (Ir/CeO 2 ) nanocatalysts. Ir species demonstrated a strong metal-support interaction (SMSI) with the CeO 2 substrate. The chemical state of Ir could be finely tuned by altering the loading of the metal. In the carbon dioxide (CO 2 ) hydrogenation reaction it was shown that the chemical state of Ir species-induced by a SMSI-has a major impact on the reaction selectivity. Direct evidence is provided indicating that a single-site catalyst is not a prerequisite for inhibition of methanation and sole production of carbon monoxide (CO) in CO 2 hydrogenation. Instead, modulation of the chemical state of metal species by a strong metal-support interaction is more important for regulation of the observed selectivity (metallic Ir particles select for methane while partially oxidized Ir species select for CO production). The study provides insight into heterogeneous catalysts at nano, sub-nano, and atomic scales. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Energy Technology Data Exchange (ETDEWEB)
Wang, Yan [Univ. of Tennessee, Knoxville, TN (United States); Rademaker, Louk [Univ. of California, Santa Barbara, CA (United States); Dagotto, Elbio R. [Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Johnston, Steven [Univ. of Tennessee, Knoxville, TN (United States)
2017-08-18
Here, the discovery of an enhanced superconducting transition temperature T_{c} in monolayers of FeSe grown on several oxide substrates has opened a new route to high-T_{c} superconductivity through interface engineering. One proposal for the origin of the observed enhancement is an electronphonon (e-ph) interaction across the interface that peaked at small momentum transfers. In this paper, we examine the implications of such a coupling on the phononic properties of the system. We show that a strong forward scattering leads to a sizable broadening of phonon lineshape, which may result in charge instabilities at long-wavelengths. However, we further find that the inclusion of Coulombic screening significantly reduces the phonon broadening. Our results show that one might not expect anomalously broad phonon linewidths in the FeSe interface systems, despite the fact that the e-ph interaction has a strong peak in the forward scattering (small \\bfq ) direction.
Energy Technology Data Exchange (ETDEWEB)
Kaur, Maninder; Dai, Qilin; Bowden, Mark E.; Engelhard, Mark H.; Wu, Yaqiao; Tang, Jinke; Qiang, You
2013-06-26
Chromium (Cr) forms a solid solution with iron (Fe) lattice when doped in core-shell iron -iron oxide nanocluster (NC) and shows a mixed phase of sigma (σ) FeCr and bcc Fe. The Cr dopant affects heavily the magnetization and magnetic reversal process, and causes the hysteresis loop to shrink near the zero field axis. Dramatic transformation happens from dipolar interaction (0 at. % Cr) to strong exchange interaction (8 at. % of Cr) is confirmed from the Henkel plot and delta M plot, and is explained by a water-melon model of core-shell NC system.
Ocampo-Torres, F. J.; García-Nava, H.; Durazo, R.; Osuna, P.; Díaz Méndez, G. M.; Graber, H. C.
2011-03-01
The Gulf of Tehuantepec air-sea interaction experiment ( intOA) took place from February to April 2005, under the Programme for the Study of the Gulf of Tehuantepec (PEGoT, Spanish acronym for Programa para el Estudio del Golfo de Tehuantepec). PEGoT is underway aiming for better knowledge of the effect of strong and persistent offshore winds on coastal waters and their natural resources, as well as performing advanced numerical modelling of the wave and surface current fields. One of the goals of the intOA experiment is to improve our knowledge on air-sea interaction processes with particular emphasis on the effect of surface waves on the momentum flux for the characteristic and unique conditions that occur when strong Tehuano winds blow offshore against the Pacific Ocean long period swell. For the field campaign, an air-sea interaction spar (ASIS) buoy was deployed in the Gulf of Tehuantepec to measure surface waves and the momentum flux between the ocean and the atmosphere. High frequency radar systems (phase array type) were in operation from two coastal sites and three acoustic Doppler current profilers were deployed near-shore. Synthetic aperture radar images were also acquired as part of the remote sensing component of the experiment. The present paper provides the main results on the wave and wind fields, addressing the direct calculation of the momentum flux and the drag coefficient, and gives an overview of the intOA experiment. Although the effect of swell has been described in recent studies, this is the first time for the very specific conditions encountered, such as swell persistently opposing offshore winds and locally generated waves, to show a clear evidence of the influence on the wind stress of the significant steepness of swell waves.
Parthasarathy, Venkatakrishnan; Fery-Forgues, Suzanne; Campioli, Elisa; Recher, Gaëlle; Terenziani, Francesca; Blanchard-Desce, Mireille
2011-11-18
Two related triphenylamine-based dipolar and octupolar fluorophores are used to prepare aqueous suspensions of fluorescent organic nanoparticles (FONs) via the reprecipitation method. The obtained spherical nanoparticles (30-40 nm in diameter) are fluorescent in aqueous solution (up to 15% fluorescence quantum yield) and exhibit extremely high one- and two-photon brightness, superior to those obtained for quantum dots. Despite the two chromophores showing similar fluorescence in solution, the fluorescence of FONs made from the octupolar derivative is significantly red-shifted compared to that generated by the dipolar FONs. In addition, the maximum two-photon absorption cross section of the FONs made from the octupolar derivative is 55% larger than that of the dipolar derivative FONs. The experimental observations provide evidence that the different molecular shape (rodlike versus three-branched) and charge distribution (dipolar versus octupolar) of the two chromophores strongly affect the packing inside the nanoparticles as well as their spectroscopic properties and colloidal stability in pure water. The use of these FONs as probes for biphotonic in-vivo imaging is investigated on Xenopus laevis tadpoles to test their utilization for angiography. When using FONs made from the octupolar dye, the formation of microagglomerates (2-5 μm scale) is observed in vivo, with subsequent lethal occlusion of the blood vessels. Conversely, the nanoparticles of the dipolar dye allow acute imaging of blood vessels thanks to their suitable size and brightness, while no toxic effect is observed. Such a goal cannot be achieved with the dissolved dye, which permeates the vessel walls. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Sahu, Debashis; Dey, Santu; Pathak, Tanmaya; Ganguly, Bishwajit
2014-04-18
DFT (M06-L) calculations on the transition state for the 1,3-dipolar cycloadditions between substituted vinyl sulfones with sugar azide have been reported in conjunction with new experimental results, and the origin of reversal of regioselectivity has been revealed using a distortion/interaction model. This study provides the scientific justification for combining organic azides with two different types of vinyl sulfones for the preparation of 1,5-disubstituted 1,2,3-triazoles and 1,4-disubstituted triazolyl esters under metal-free conditions.
Nuclear magnetic relaxation by the dipolar EMOR mechanism: Multi-spin systems
Chang, Zhiwei; Halle, Bertil
2017-08-01
In aqueous systems with immobilized macromolecules, including biological tissues, the longitudinal spin relaxation of water protons is primarily induced by exchange-mediated orientational randomization (EMOR) of intra- and intermolecular magnetic dipole-dipole couplings. Starting from the stochastic Liouville equation, we have previously developed a rigorous EMOR relaxation theory for dipole-coupled two-spin and three-spin systems. Here, we extend the stochastic Liouville theory to four-spin systems and use these exact results as a guide for constructing an approximate multi-spin theory, valid for spin systems of arbitrary size. This so-called generalized stochastic Redfield equation (GSRE) theory includes the effects of longitudinal-transverse cross-mode relaxation, which gives rise to an inverted step in the relaxation dispersion profile, and coherent spin mode transfer among solid-like spins, which may be regarded as generalized spin diffusion. The GSRE theory is compared to an existing theory, based on the extended Solomon equations, which does not incorporate these phenomena. Relaxation dispersion profiles are computed from the GSRE theory for systems of up to 16 protons, taken from protein crystal structures. These profiles span the range from the motional narrowing limit, where the coherent mode transfer plays a major role, to the ultra-slow motion limit, where the zero-field rate is closely related to the strong-collision limit of the dipolar relaxation rate. Although a quantitative analysis of experimental data is beyond the scope of this work, it is clear from the magnitude of the predicted relaxation rate and the shape of the relaxation dispersion profile that the dipolar EMOR mechanism is the principal cause of water-1H low-field longitudinal relaxation in aqueous systems of immobilized macromolecules, including soft biological tissues. The relaxation theory developed here therefore provides a basis for molecular-level interpretation of endogenous soft
Dudin, G. N.; Ledovskiy, A. V.
2013-06-01
The flow in a spatial hypersonic laminar boundary layer on a planar wing with a point of inflection in the leading edge is considered in the regime of strong viscous-inviscid interaction. The boundary problems are formulated for two cases: self-similar flow near the point of inflection of the leading edge and full three-dimensional (3D) boundary layer on a wing with variable sweep angle. The numerical solution is obtained using the finite-difference method. The results of parametric calculations of influence of a wing shape and the temperature factor on flow characteristics in the boundary layer are presented. The possibility of formation of local regions with high shear stress and heat flux is shown.
DEFF Research Database (Denmark)
Marchukov, O. V.; Eriksen, E. H.; Midtgaard, J. M.
2016-01-01
One-dimensional multi-component Fermi or Bose systems with strong zero-range interactions can be described in terms of local exchange coefficients and mapping the problem into a spin model is thus possible. For arbitrary external confining potentials the local exchanges are given by highly non...... to the computational complexity of the high-dimensional integrals involved. An approach using the local density approximation would therefore be a most welcome approximation due to its simplicity. Here we assess the accuracy of the local density approximation by going beyond the simple harmonic oscillator that has...... been the focus of previous studies and consider some double-wells of current experimental interest. We find that the local density approximation works quite well as long as the potentials resemble harmonic wells but break down for larger barriers. In order to explore the consequences of applying...
Zero field entanglement in dipolar coupling spin system at negative temperatures
Furman, Gregory B.; Meerovich, Victor M.; Sokolovsky, Vladimir L.
2013-01-01
A dipolar coupled spin system can achieve internal thermodynamic equilibrium states at negative absolute temperature. We study analytically and numerically the temperature dependence of the concurrence in a dipolar coupled spin-1/2 system in both non-zero and zero fields and show that, at negative temperatures, entangled states can exist even in zero magnetic field.
Jordanova, V. K.; Zaharia, S.; Welling, D. T.
2010-12-01
The effects of nondipolar magnetic field configuration and the feedback of a self-consistently computed magnetic field on ring current dynamics are investigated during a double-dip storm with minima SYM-H = -90 nT at ˜2000 UT, 20 November, and SYM-H = -127 nT at ˜1000 UT, 21 November 2002. We use our kinetic ring current-atmosphere interactions model with self-consistent magnetic field (RAM-SCB) to study the redistribution of plasma in the inner magnetosphere after its fresh injection from the plasma sheet. The kinetic model is fully extended to nondipolar magnetic (B) field geometry and two-way coupled with an Euler-potential-based equilibrium model that calculates self-consistently the three-dimensional magnetic field in force balance with the anisotropic ring current distributions. The ring current source population is inferred from LANL geosynchronous satellite data; a superdense plasma sheet observed during the second storm main phase contributes significantly to ring current buildup. We find that the bounce-averaged velocities increase while the bounce-averaged geocoronal hydrogen densities decrease on the nightside when a nondipolar B field is used. A depression of the ring current fluxes and a confinement of the ring current close to Earth are thus observed on the nightside as geomagnetic activity increases. In contrast to the dipolar case, the proton anisotropy increases considerably in the postnoon sector, and the nondipolar simulations predict the excitation of intense EMIC waves at large L shells. The total ring current energy and ∣Dst∣ index calculated with the self-consistent B field are in best agreement with observations, being smaller compared to the dipolar calculations but larger than the empirical B field predictions.
Gaona, Jaime; Lewandowski, Jörg
2017-04-01
The quantification of groundwater-surface water interactions is not only required for budgets but also for an understanding of the complex relations between hyporheic exchange flows (HEF) and the associated chemical and biological processes that take place in hyporheic zones (HZ). Thus, there is a strong need to improve methods for flux estimation.The present study aims to quantify the vertical fluxes across the riverbed from data of temperature depth profiles recorded at the River Schlaube in East Brandenburg, Germany. In order to test the capabilities and limitations of existing methods, fluxes were calculated with an analytical (VFLUX, based on the amplitude attenuation and phase shift analysis) and a numerical (1DTempPro, parametrization based on observed values) approach for heat conduction. We conclude that the strong limitations of the flux estimates are caused by thermal and hydraulic heterogeneities of the sediment properties. Consequently, upscaling of fluxes must include other thermal techniques able to portray the spatial variability of thermal patterns, along with further developments of methods to link thermal depth profiles, thermal patterns of the surface of the streambed and all the other factors involved. Considering time and costs of temperature depth profiles of riverbeds, and the need for multiple devices to cover larger areas, it is additionally tested whether vertical fluxes can be infered from the uppermost temperature sensors of a data set. That would ease hyporheic investigations at larger scales.
Yuan, Wen-Kui; Cui, Tao; Liu, Wei; Wen, Li-Rong; Li, Ming
2018-03-16
A new CuI/1,10-phen-catalyzed reaction for the synthesis of 3-ylideneoxindoles from readily available isatins and ethyl isocyanoacetate, in which ethyl isocyanoacetate acts as a latent two-carbon donor like the Wittig reagent, is reported. A tandem procedure including 1,3-dipolar cycloaddition/inverse 1,3-dipolar ring opening/olefination allows the preparation of 3-ylideneoxindoles with broad functional group tolerance.
Thermo-molecular orientation effects in fluids of dipolar dumbbells.
Daub, Christopher D; Åstrand, Per-Olof; Bresme, Fernando
2014-10-28
We use molecular dynamics simulations in applied thermal gradients to study thermomolecular orientation (TMO) of size-asymmetric dipolar dumbbells with different molecular dipole moments. We find that the direction of the TMO is the same as in apolar dumbbells of the same size, i.e. the smaller atom in the dumbbell tends to orient towards the colder temperature. The ratio of the electrical polarization to the magnitude of the thermal gradient does not vary much with the magnitude of the molecular dipole moment. We also investigate a novel second order TMO that persists even in size-symmetric dipolar dumbbells where molecules have a slight tendency to orient perpendicular to the gradient except very close to the hot region, where (anti-)parallel orientations are preferred. Finally, we investigate rotational correlation functions and characteristic rotational times in these systems in an attempt to model possible spectroscopic signatures of TMO in experiments. Although we cannot detect any difference in integrated rotational times between equilibrium simulations and simulations in a thermal gradient, more careful modelling of the anisotropic rotational dynamics in the thermal gradient may be more successful.
Dynamical simulation of dipolar Janus colloids: dynamical properties.
Hagy, Matthew C; Hernandez, Rigoberto
2013-05-14
The dynamical properties of dipolar Janus particles are studied through simulation using our previously-developed detailed pointwise (PW) model and an isotropically coarse-grained (CG) model [M. C. Hagy and R. Hernandez, J. Chem. Phys. 137, 044505 (2012)]. The CG model is found to have accelerated dynamics relative to the PW model over a range of conditions for which both models have near identical static equilibrium properties. Physically, this suggests dipolar Janus particles have slower transport properties (such as diffusion) in comparison to isotropically attractive particles. Time rescaling and damping with Langevin friction are explored to map the dynamics of the CG model to that of the PW model. Both methods map the diffusion constant successfully and improve the velocity autocorrelation function and the mean squared displacement of the CG model. Neither method improves the distribution of reversible bond durations f(tb) observed in the CG model, which is found to lack the longer duration reversible bonds observed in the PW model. We attribute these differences in f(tb) to changes in the energetics of multiple rearrangement mechanisms. This suggests a need for new methods that map the coarse-grained dynamics of such systems to the true time scale.
Single-molecule magnets ``without'' intermolecular interactions
Wernsdorfer, W.; Vergnani, L.; Rodriguez-Douton, M. J.; Cornia, A.; Neugebauer, P.; Barra, A. L.; Sorace, L.; Sessoli, R.
2012-02-01
Intermolecular magnetic interactions (dipole-dipole and exchange) affect strongly the magnetic relaxation of crystals of single-molecule magnets (SMMs), especially at low temperature, where quantum tunneling of the magnetization (QTM) dominates. This leads to complex many-body problems [l]. Measurements on magnetically diluted samples are desirable to clearly sort out the behaviour of magnetically-isolated SMMs and to reveal, by comparison, the effect of intermolecular interactions. Here, we diluted a Fe4 SMM into a diamagnetic crystal lattice, affording arrays of independent and iso-oriented magnetic units. We found that the resonant tunnel transitions are much sharper, the tunneling efficiency changes significantly, and two-body QTM transitions disappear. These changes have been rationalized on the basis of a dipolar shuffling mechanism and of transverse dipolar fields, whose effect has been analyzed using a multispin model. Our findings directly prove the impact of intermolecular magnetic couplings on the SMM behaviour and disclose the magnetic response of truly-isolated giant spins in a diamagnetic crystalline environment.[4pt] [1] W. Wernsdorfer, at al, PRL 82, 3903 (1999); PRL 89, 197201 (2002); Nature 416, 406 (2002); IS Tupitsyn, PCE Stamp, NV Prokof'ev, PRB 69, 132406 (2004).
González-Durruthy, Michael; Werhli, Adriano V; Seus, Vinicius; Machado, Karina S; Pazos, Alejandro; Munteanu, Cristian R; González-Díaz, Humberto; Monserrat, José M
2017-10-16
The current molecular docking study provided the Free Energy of Binding (FEB) for the interaction (nanotoxicity) between VDAC mitochondrial channels of three species (VDAC1-Mus musculus, VDAC1-Homo sapiens, VDAC2-Danio rerio) with SWCNT-H, SWCNT-OH, SWCNT-COOH carbon nanotubes. The general results showed that the FEB values were statistically more negative (p (SWCNT-VDAC1-Mus musculus) > (SWCNT-VDAC1-Homo sapiens) > (ATP-VDAC). More negative FEB values for SWCNT-COOH and OH were found in VDAC2-Danio rerio when compared with VDAC1-Mus musculus and VDAC1-Homo sapiens (p r 2 > 0.97) was observed between n-Hamada index and VDAC nanotoxicity (or FEB) for the zigzag topologies of SWCNT-COOH and SWCNT-OH. Predictive Nanoparticles-Quantitative-Structure Binding-Relationship models (nano-QSBR) for strong and weak SWCNT-VDAC docking interactions were performed using Perturbation Theory, regression and classification models. Thus, 405 SWCNT-VDAC interactions were predicted using a nano-PT-QSBR classifications model with high accuracy, specificity, and sensitivity (73-98%) in training and validation series, and a maximum AUROC value of 0.978. In addition, the best regression model was obtained with Random Forest (R 2 of 0.833, RMSE of 0.0844), suggesting an excellent potential to predict SWCNT-VDAC channel nanotoxicity. All study data are available at https://doi.org/10.6084/m9.figshare.4802320.v2 .
Energy Technology Data Exchange (ETDEWEB)
Buljubasich, Lisandro; Dente, Axel D.; Levstein, Patricia R.; Chattah, Ana K.; Pastawski, Horacio M. [Instituto de Física Enrique Gaviola (IFEG-CONICET), Córdoba 5000 (Argentina); Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba, Ciudad Universitaria, Córdoba 5000 (Argentina); Sánchez, Claudia M. [Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba, Ciudad Universitaria, Córdoba 5000 (Argentina)
2015-10-28
We performed Loschmidt echo nuclear magnetic resonance experiments to study decoherence under a scaled dipolar Hamiltonian by means of a symmetrical time-reversal pulse sequence denominated Proportionally Refocused Loschmidt (PRL) echo. The many-spin system represented by the protons in polycrystalline adamantane evolves through two steps of evolution characterized by the secular part of the dipolar Hamiltonian, scaled down with a factor |k| and opposite signs. The scaling factor can be varied continuously from 0 to 1/2, giving access to a range of complexity in the dynamics. The experimental results for the Loschmidt echoes showed a spreading of the decay rates that correlate directly to the scaling factors |k|, giving evidence that the decoherence is partially governed by the coherent dynamics. The average Hamiltonian theory was applied to give an insight into the spin dynamics during the pulse sequence. The calculations were performed for every single radio frequency block in contrast to the most widely used form. The first order of the average Hamiltonian numerically computed for an 8-spin system showed decay rates that progressively decrease as the secular dipolar Hamiltonian becomes weaker. Notably, the first order Hamiltonian term neglected by conventional calculations yielded an explanation for the ordering of the experimental decoherence rates. However, there is a strong overall decoherence observed in the experiments which is not reflected by the theoretical results. The fact that the non-inverted terms do not account for this effect is a challenging topic. A number of experiments to further explore the relation of the complete Hamiltonian with this dominant decoherence rate are proposed.
Miller, A. A.; Cao, Y.; Piro, A. L.; Blagorodnova, N.; Bue, B. D.; Cenko, S. B.; Dhawan, S.; Ferretti, R.; Fox, O. D.; Fremling, C.; Goobar, A.; Howell, D. A.; Hosseinzadeh, G.; Kasliwal, M. M.; Laher, R. R.; Lunnan, R.; Masci, F. J.; McCully, C.; Nugent, P. E.; Sollerman, J.; Taddia, F.; Kulkarni, S. R.
2018-01-01
Early observations of Type Ia supernovae (SNe Ia) provide a unique probe of their progenitor systems and explosion physics. Here we report the intermediate Palomar Transient Factory (iPTF) discovery of an extraordinarily young SN Ia, iPTF 16abc. By fitting a power law to our early light curve, we infer that first light for the SN, that is, when the SN could have first been detected by our survey, occurred only 0.15{+/- }0.070.15 days before our first detection. In the ∼24 hr after discovery, iPTF 16abc rose by ∼2 mag, featuring a near-linear rise in flux for ≳ 3 days. Early spectra show strong C II absorption, which disappears after ∼7 days. Unlike the extensively observed Type Ia SN 2011fe, the {(B-V)}0 colors of iPTF 16abc are blue and nearly constant in the days after explosion. We show that our early observations of iPTF 16abc cannot be explained by either SN shock breakout and the associated, subsequent cooling or the SN ejecta colliding with a stellar companion. Instead, we argue that the early characteristics of iPTF 16abc, including (i) the rapid, near-linear rise, (ii) the nonevolving blue colors, and (iii) the strong C II absorption, are the result of either ejecta interaction with nearby, unbound material or vigorous mixing of radioactive 56Ni in the SN ejecta, or a combination of the two. In the next few years, dozens of very young normal SNe Ia will be discovered, and observations similar to those presented here will constrain the white dwarf explosion mechanism.
Terletska, Kateryna; Maderich, Vladimir; Brovchenko, Igor; Jung, Kyung Tae
2013-04-01
In the freshwater lakes in moderate latitudes stratification occurs as a result of the seasonal warming of the surface water layer. Than the intense wind surges (usually in autumn) tilt the surface and generate long basin-scale low-frequency standing internal waves (seiches). Depending on the initial interface tilt and stratification wide spectra of possible flow regimes can be observed [1]-[2].They varied from small amplitude symmetric seiches to large amplitude nonlinear waves.Nonlinearity leads to an asymmetry of internal waves and appearance of the surge or bore and further disintegration of it on a sequence of solitary waves. In present study degeneration of the strongly nonlinear internal seiches in elongated lakes with a concave "spoon-like" topography is investigated.Two different three-dimensional non-hydrostatic free-surface numerical models are used to investigate degeneration of large internal waves and its subsequent interaction with the concave lake slope. One of this model is non-hydrostatic model [3] and the other is a well-known MIT model. At first we consider idealized elongated elliptic-shape lake with the dimension of 5 km X 1 km with the maximal depth 30 m. The stratification in lake is assumed to be given in a form of the tangent function with a density difference between upper and lower layers 2 kgm-3 . It is assumed that motion in such lake is initiated by inclination of thermocline on a certain angle. Than lake adjusts to return to its original state producing internal seiches which begin interacting with a bottom topography. The process of degeneration of internal seiches in the lake with concave ends consist of chain of elementary processes: 1) steeping of long basin scale large amplitude wave, that evolve into internal surge, 2) surge interact with concave lake ends that leads the concentration of the flow and formation of down slope bottom jet along the lake axis, 3) due to cumulative effect local velocity in the jet accelerates up to
Zhao, Yun; Law, Henry C H; Zhang, Zaijun; Lam, Herman C; Quan, Quan; Li, Guohui; Chu, Ivan K
2015-10-09
In this study we developed a fully automated three-dimensional (3D) liquid chromatography methodology-comprising hydrophilic interaction separation as the first dimension, strong cation exchange fractionation as the second dimension, and low-pH reversed-phase (RP) separation as the third dimension-in conjunction downstream with additional complementary porous graphitic carbon separation, to capture non-retained hydrophilic analytes, for both shotgun proteomics and N-glycomics analyses. The performance of the 3D system alone was benchmarked through the analysis of the total lysate of Saccharomyces cerevisiae, leading to improved hydrophilic peptide coverage, from which we identified 19% and 24% more proteins and peptides, respectively, relative to those identified from a two-dimensional hydrophilic interaction liquid chromatography and low-pH RP chromatography (HILIC-RP) system over the same mass spectrometric acquisition time; consequently, the 3D platform also provided enhanced proteome and protein coverage. When we applied the integrated technology to analyses of the total lysate of primary cerebellar granule neurons, we characterized a total of 2201 proteins and 16,937 unique peptides for this primary cell line, providing one of its most comprehensive datasets. Our new integrated technology also exhibited excellent performance in the first N-glycomics analysis of cynomolgus monkey plasma; we successfully identified 122 proposed N-glycans and 135 N-glycosylation sites from 122 N-glycoproteins, and confirmed the presence of 38 N-glycolylneuraminic acid-containing N-glycans, a rare occurrence in human plasma, through tandem mass spectrometry for the first time. Copyright © 2015 Elsevier B.V. All rights reserved.
Nuclear dipolar magnetism around one microkelvin in calciumhydroxide
International Nuclear Information System (INIS)
Marks, J.
1985-01-01
This thesis is devoted to a study of dipolar magnetism of the proton spins in Ca(OH) 2 . First, cooling techniques are described. The energy of different spin configurations are calculated in the Weiss-field approximation. Crystallographic characteristics of Ca(OH) 2 are described, as well as a method to produce monocrystals and a method for crystal doping using 1.5 MeV electron beams. It is shown that the polarization mechanism of the proton spins in Ca(OH) 2 doped with O 2 - centra is the 'Solid Effect'. Susceptibility measurements are presented as a function of the polarization. Results imply that both at positive and at negative temperatures state ordering sets in, characterized by a plateau in the susceptibility. (Auth/G.J.P.)
Energetic Electron Acceleration and Injection During Dipolarization Events in Mercury's Magnetotail
Dewey, Ryan M.; Slavin, James A.; Raines, Jim M.; Baker, Daniel N.; Lawrence, David J.
2017-12-01
Energetic particle bursts associated with dipolarization events within Mercury's magnetosphere were first observed by Mariner 10. The events appear analogous to particle injections accompanying dipolarization events at Earth. The Energetic Particle Spectrometer (3 s resolution) aboard MESSENGER determined the particle bursts are composed entirely of electrons with energies ≳ 300 keV. Here we use the Gamma-Ray Spectrometer high-time-resolution (10 ms) energetic electron measurements to examine the relationship between energetic electron injections and magnetic field dipolarization in Mercury's magnetotail. Between March 2013 and April 2015, we identify 2,976 electron burst events within Mercury's magnetotail, 538 of which are closely associated with dipolarization events. These dipolarizations are detected on the basis of their rapid ( 2 s) increase in the northward component of the tail magnetic field (ΔBz 30 nT), which typically persists for 10 s. Similar to those at Earth, we find that these dipolarizations appear to be low-entropy, depleted flux tubes convecting planetward following the collapse of the inner magnetotail. We find that electrons experience brief, yet intense, betatron and Fermi acceleration during these dipolarizations, reaching energies 130 keV and contributing to nightside precipitation. Thermal protons experience only modest betatron acceleration. While only 25% of energetic electron events in Mercury's magnetotail are directly associated with dipolarization, the remaining events are consistent with the Near-Mercury Neutral Line model of magnetotail injection and eastward drift about Mercury, finding that electrons may participate in Shabansky-like closed drifts about the planet. Magnetotail dipolarization may be the dominant source of energetic electron acceleration in Mercury's magnetosphere.
Pereira, Jorge F B; Barber, Patrick S; Kelley, Steven P; Berton, Paula; Rogers, Robin D
2017-10-11
The properties of double salt ionic liquids based on solutions of cholinium acetate ([Ch][OAc]), ethanolammonium acetate ([NH 3 (CH 2 ) 2 OH][OAc]), hydroxylammonium acetate ([NH 3 OH][OAc]), ethylammonium acetate ([NH 3 CH 2 CH 3 ][OAc]), and tetramethylammonium acetate ([N(CH 3 ) 4 ][OAc]) in 1-ethyl-3-methylimidazolium acetate ([C 2 mim][OAc]) were investigated by NMR spectroscopy and X-ray crystallography. Through mixture preparation, the solubility of [N(CH 3 ) 4 ][OAc] is the lowest, and [Ch][OAc] shows a 3-fold lower solubility than the other hydroxylated ammonium acetate-based salts in [C 2 mim][OAc] at room temperature. NMR and X-ray crystallographic studies of the pure salts suggest that the molecular-level mechanisms governing such miscibility differences are related to the weaker interactions between the -NH 3 groups and [OAc] - , even though three of these salts possess the same strong 1 : 1 hydrogen bonds between the cation -OH group and the [OAc] - ion. The formation of polyionic clusters between the anion and those cations with unsatisfied hydrogen bond donors seems to be a new tool by which the solubility of these salts in [C 2 mim][OAc] can be controlled.
Kakwere, Hamilton
2015-04-03
Herein we prepare nanohybrids by incorporating iron oxide nanocubes (cubic-IONPs) within a thermo-responsive polymer shell that can act as drug carriers for doxorubicin(doxo). The cubic-shaped nanoparticles employed are at the interface between superparamagnetic and ferromagnetic behavior and have an exceptionally high specific absorption rate (SAR) but their functionalization is extremely challenging compared to bare superparamagnetic iron oxide nanoparticles as they strongly interact with each other. By conducting the polymer grafting reaction using reversible addition-fragmentation chain transfer (RAFT) polymerization in a viscous solvent medium, we have here developed a facile approach to decorate the nanocubes with stimuli-responsive polymers. When the thermo-responsive shell is composed of poly(N-isopropyl acrylamide-co-polyethylene glycolmethylether acrylate), nanohybrids have a phase transition temperature, the lower critical solution temperature (LCST), above 37 °C in physiological conditions. Doxo loaded nanohybrids exhibited a negligible drug release below 37 °C but showed a consistent release of their cargo on demand by exploiting the capability of the nanocubes to generate heat under an alternating magnetic field (AMF). Moreover, the drug free nanocarrier does not exhibit cytotoxicity even when administered at high concentration of nanocubes (1g/L of iron) and internalized at high extent (260 pg of iron per cell). We have also implemented the synthesis protocol to decorate the surface of nanocubes with poly(vinylpyridine) polymer and thus prepare pH-responsive shell coated nanocubes.
Strongly Correlated Topological Insulators
2016-02-03
Strongly Correlated Topological Insulators In the past year, the grant was used for work in the field of topological phases, with emphasis on finding...surface of topological insulators. In the past 3 years, we have started a new direction, that of fractional topological insulators. These are materials...in which a topologically nontrivial quasi-flat band is fractionally filled and then subject to strong interactions. The views, opinions and/or
International Nuclear Information System (INIS)
Capsal, Jean-Fabien; Lallart, Mickaël; Galineau, Jeremy; Cottinet, Pierre-Jean; Sebald, Gaël; Guyomar, Daniel
2012-01-01
Electrostrictive polymers, as an important category of electroactive polymers, are known to have non-linear response in terms of actuation that strongly affects their dynamic performance and limits their applications. Very few models exist in the literature, and even fewer are capable of making reliable predictions under an electric field. In this paper, electrostrictive strain of dipolar polymeric systems is discussed through constitutive equations derived from the Boltzmann statistics and Debye/Langevin formalism. Macroscopic polarization is expressed as a function of the inherent microscopic parameters of the dielectric material. Electrostrictive strain, polarization and dielectric permittivity are described well by the model in terms of dipole moment and saturation of dipole orientation, allowing the physical definition of the electrostrictive coefficient Q. Maxwell forces generated by dipolar orientation inducing surface charges are also used to explain the electrostrictive strain of polymers. The assessment of this analysis through a comparison with experimental data shows good agreement between reported values and theoretical predictions. These materials are generally used in low-frequency applications, thus the interfacial phenomena that are responsible for low saturation electric field should not be omitted so as not to underestimate or overestimate the low electric field response of the electrostrictive strain. (paper)
International Nuclear Information System (INIS)
Kozioł-Rachwał, A.; Skowroński, W.; Frankowski, M.; Chęciński, J.; Ziętek, S.; Rzeszut, P.; Ślęzak, M.; Matlak, K.; Ślęzak, T.; Stobiecki, T.; Korecki, J.
2017-01-01
Fe/MgO/Fe trilayers with a subnanometer MgO tunnel barrier were grown by molecular beam epitaxy. Longitudinal magnetooptic Kerr effect measurements confirmed the existence of the antiferromagnetic interlayer exchange coupling (IEC) between the Fe layers for 2 Å
Energy Technology Data Exchange (ETDEWEB)
Kozioł-Rachwał, A. [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. Mickiewicza 30, 30-059 Kraków (Poland); National Institute of Advanced Industrial Science and Technology, Spintronics Research Center, Tsukuba, Ibaraki 305-8568 (Japan); Skowroński, W.; Frankowski, M. [AGH University of Science and Technology, Department of Electronics, al. Mickiewicza 30, 30-059 Kraków (Poland); Chęciński, J. [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. Mickiewicza 30, 30-059 Kraków (Poland); AGH University of Science and Technology, Department of Electronics, al. Mickiewicza 30, 30-059 Kraków (Poland); Ziętek, S.; Rzeszut, P. [AGH University of Science and Technology, Department of Electronics, al. Mickiewicza 30, 30-059 Kraków (Poland); Ślęzak, M.; Matlak, K.; Ślęzak, T. [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. Mickiewicza 30, 30-059 Kraków (Poland); Stobiecki, T. [AGH University of Science and Technology, Department of Electronics, al. Mickiewicza 30, 30-059 Kraków (Poland); Korecki, J. [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. Mickiewicza 30, 30-059 Kraków (Poland); Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, ul. Niezapominajek 8, 30-239 Kraków (Poland)
2017-02-15
Fe/MgO/Fe trilayers with a subnanometer MgO tunnel barrier were grown by molecular beam epitaxy. Longitudinal magnetooptic Kerr effect measurements confirmed the existence of the antiferromagnetic interlayer exchange coupling (IEC) between the Fe layers for 2 Å
Nose, M.; Keika, K.; Kletzing, C. A.; Spence, H. E.; Smith, C. W.; MacDowall, R. J.; Reeves, G. D.; Larsen, B. A.; Mitchell, D. G.
2016-01-01
We investigate the magnetic field dipolarization in the inner magnetosphere and its associated ion flux variations, using the magnetic field and energetic ion flux data acquired by the Van Allen Probes. From a study of 74 events that appeared at L= 4.5-6.6 between 1 October 2012 and 31 October 2013, we reveal the following characteristics of the dipolarization in the inner magnetosphere: (1) its time scale is approximately 5 min; (2) it is accompanied by strong magnetic fluctuations that have a dominant frequency close to the O+ gyrofrequency; (3) ion fluxes at 20-50 keV are simultaneously enhanced with larger magnitudes for O+ than for H+; (4) after a few minutes of the dipolarization, the flux enhancement at 0.1-5 keV appears with a clear energy-dispersion signature only for O+; and (5) the energy-dispersed O+ flux enhancement appears in directions parallel or antiparallel to the magnetic field. From these characteristics, we discuss possible mechanisms that can provide selective acceleration to O+ ions at > 20 keV. We conclude that O+ ions at L= 5.4-6.6 undergo nonadiabatic local acceleration caused by oscillating electric field associated with the magnetic fluctuations and/or adiabatic convective transport from the plasma sheet to the inner magnetosphere by the impulsive electric field. At L= 4.5-5.4, however, only the former acceleration is plausible. We also conclude that the field-aligned energy-dispersed O+ ions at 0.1-5 keV originate from the ionosphere and are extracted nearly simultaneously to the onset of the dipolarization.
Helical Polyisocyanopeptides as Lyotropic Liquid Crystals for Measuring Residual Dipolar Couplings.
Li, Gao-Wei; Cao, Jiang-Ming; Zong, Wen; Hu, Li; Hu, Mao-Lin; Lei, Xinxiang; Sun, Han; Tan, Ren Xiang
2017-06-07
Residual dipolar couplings (RDC) emerged to be an important structural parameter for organic and biomolecules. Herein, a new helical polyisocyanopeptide (l,l-PIAF-OBn) that forms lyotropic liquid crystals (LLC) in CDCl 3 is proposed as a novel weakly orienting medium for acquiring residual dipolar couplings (RDCs) of organic molecules. We demonstrate its application for the structural elucidation of strychnine and triptolide. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Statistical mechanics of molecular fluids. The RHNC theory applied to hard dipolar spheres
International Nuclear Information System (INIS)
Lombardero, M.; Lado, F.; Abascal, J.L.F.; Lago, S.; Enciso, E.
1988-01-01
The RHNC (reference hipernetted chain) equation, together with an optimization criterion which extremalizes the Helmholtz free energy, is used to obtain structural, thermodynamic, and dielectric properties of a system made up of hard dipolar spheres. The comparison with simulation results is made in the same boundary conditions and then the properties of an infinite system are evaluated for a variaty of states at different densities and dipolar moments. (Author)
Dipolar-Biased Tunneling of Magnetization in Crystals of Single Molecule Magnets
Awaga, Kunio
2007-03-01
The molecular cluster Mn12 has attracted much interest as a single-molecule magnet (SMM) and as a multi-redox system. It has a high-spin ground state of S=10 and a strong uniaxial magnetic anisotropy, and the combination of the two natures makes an effective potential barrier between the up and down spin states. At low temperatures, the magnetization curve exhibited a hysteresis loop and the quantum tunneling of magnetization (QTM). In the present work, we studied the structure and magnetic properties of the mixed-metal SMM, Mn11Cr, through the analysis of Mn11Cr/Mn12 mixed crystal. High-frequency EPR spectra were well explained by assuming that Mn11Cr was in a ground spin-state of S=19/2 with nearly the same EPR parameter set as for Mn12. QTM in Mn11Cr was observed with the same field interval as for Mn12. The magnetization of Mn11Cr and Mn12 in the mixed crystal can be independently manipulated by utilizing the difference between their coercive fields. The resonance fields of QTM in Mn11Cr are significantly affected by the magnetization direction of Mn12, suggesting the effect of dipolar-biased tunneling. Besides SMM, we would also like to report the unusual magnetic properties of spherical hollow nanomagnets, the electrical properties of heterocyclic thiazyl radicals, and their possible applications in spintronics and organic electronics.
On the Acceleration and Anisotropy of Ions Within Magnetotail Dipolarizing Flux Bundles
Zhou, Xu-Zhi; Runov, Andrei; Angelopoulos, Vassilis; Artemyev, Anton V.; Birn, Joachim
2018-01-01
Dipolarizing flux bundles (DFBs), earthward propagating structures with enhanced northward magnetic field Bz, are usually believed to carry a distinctly different plasma population from that in the ambient magnetotail plasma sheet. The ion distribution functions within the DFB, however, have been recently found to be largely controlled by the ion adiabaticity parameter κ in the ambient plasma sheet outside the DFB. According to these observations, the ambient κ values of 2-3 usually correspond to a strong perpendicular anisotropy of suprathermal ions within the DFB, whereas for lower κ values the DFB ions become more isotropic. Here we utilize a simple, test particle model to explore the nature of the anisotropy and its dependence on the ambient κ values. We find that the anisotropy originates from successive ion reflections and reentries to the DFB, during which the ions are consecutively accelerated in the perpendicular direction by the DFB-associated electric field. This consecutive acceleration may be interrupted, however, when magnetic field lines are highly curved in the ambient plasma sheet. In this case, the ion trajectories become stochastic outside the DFB, which makes the reflected ions less likely to return to the DFB for another cycle of acceleration; as a consequence, the perpendicular ion anisotropy does not appear. Given that the DFB ions are a free energy source for instabilities when they are injected toward Earth, our simple model (that reproduces most observational features on the anisotropic DFB ion distributions) may shed new lights on the coupling process between magnetotail and inner magnetosphere.
Rapid Pitch Angle Evolution of Suprathermal Electrons Behind Dipolarization Fronts
Liu, C. M.; Fu, H. S.; Cao, J. B.; Xu, Y.; Yu, Y. Q.; Kronberg, E. A.; Daly, P. W.
2017-10-01
The pitch angle distribution (PAD) of suprathermal electrons can have both spatial and temporal evolution in the magnetotail and theoretically can be an indication of electron energization/cooling processes there. So far, the spatial evolution of PAD has been well studied, leaving the temporal evolution as an open question. To reveal the temporal evolution of electron PAD, spacecraft should monitor the same flux tube for a relatively long period, which is not easy in the dynamic magnetotail. In this study, we present such an observation by Cluster spacecraft in the magnetotail behind a dipolarization front (DF). We find that the PAD of suprathermal electrons can evolve from pancake type to butterfly type during cigar type during <8 s. During this process, the flow velocity is nearly zero and the plasma entropy is constant, meaning that the evolution is temporal. We interpret such temporal evolution using the betatron cooling process, which is driven by quasi-adiabatic expansion of flux tubes, and the magnetic mirror effect, which possibly exists behind the DF as well.
Laine, Randy Olivier
2013-01-01
The numerous and diverse extrasolar planets detected since 1995 provide much inspiration for planetary astrophysics. A fraction of these extrasolar planets orbit their host stars at semi-major axes less than 0.1 AU; a planet which has migrated toward its host star would thus first encounter a strong magnetized wind and, as it enters the stellar magnetosphere, strong magnetic fields. We model the interaction of such a close-in extrasolar planet with the dipolar magnetic field of its host star ...
Strong Electroweak Symmetry Breaking
Grinstein, Benjamin
2011-01-01
Models of spontaneous breaking of electroweak symmetry by a strong interaction do not have fine tuning/hierarchy problem. They are conceptually elegant and use the only mechanism of spontaneous breaking of a gauge symmetry that is known to occur in nature. The simplest model, minimal technicolor with extended technicolor interactions, is appealing because one can calculate by scaling up from QCD. But it is ruled out on many counts: inappropriately low quark and lepton masses (or excessive FCNC), bad electroweak data fits, light scalar and vector states, etc. However, nature may not choose the minimal model and then we are stuck: except possibly through lattice simulations, we are unable to compute and test the models. In the LHC era it therefore makes sense to abandon specific models (of strong EW breaking) and concentrate on generic features that may indicate discovery. The Technicolor Straw Man is not a model but a parametrized search strategy inspired by a remarkable generic feature of walking technicolor,...
Burba, Christopher M; Chang, Hai-Chou
2018-03-15
Continued growth and development of ionic liquids requires a thorough understanding of how cation and anion molecular structure defines the liquid structure of the materials as well as the various properties that make them technologically useful. Infrared spectroscopy is frequently used to assess molecular-level interactions among the cations and anions of ionic liquids because the intramolecular vibrational modes of the ions are sensitive to the local potential energy environments in which they reside. Thus, different interaction modes among the ions may lead to different spectroscopic signatures in the vibrational spectra. Charge organization present in ionic liquids, such as 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([C 4 mim]CF 3 SO 3 ), is frequently modeled in terms of a quasicrystalline structure. Highly structured quasilattices enable the dynamic coupling of vibrationally-induced dipole moments to produce optical dispersion and transverse optical-longitudinal optical (TO-LO) splitting of vibrational modes of the ionic liquid. According to dipolar coupling theory, the degree of TO-LO splitting is predicted to have a linear dependence on the number density of the ionic liquid. Both temperature and pressure will affect the number density of the ionic liquid and, therefore, the amount of TO-LO splitting for this mode. Therefore, we test these relationships through temperature- and pressure-dependent FT-IR spectroscopic studies of [C 4 mim]CF 3 SO 3 , focusing on the totally symmetric SO stretching mode for the anion, ν s (SO 3 ). Increased temperature decreases the amount of TO-LO splitting for ν s (SO 3 ), whereas elevated pressure is found to increase the amount of band splitting. In both cases, the experimental observations follow the general predictions of dipolar coupling theory, thereby supporting the quasilattice model for this ionic liquid. Copyright © 2017 Elsevier B.V. All rights reserved.
Burba, Christopher M.; Chang, Hai-Chou
2018-03-01
Continued growth and development of ionic liquids requires a thorough understanding of how cation and anion molecular structure defines the liquid structure of the materials as well as the various properties that make them technologically useful. Infrared spectroscopy is frequently used to assess molecular-level interactions among the cations and anions of ionic liquids because the intramolecular vibrational modes of the ions are sensitive to the local potential energy environments in which they reside. Thus, different interaction modes among the ions may lead to different spectroscopic signatures in the vibrational spectra. Charge organization present in ionic liquids, such as 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([C4mim]CF3SO3), is frequently modeled in terms of a quasicrystalline structure. Highly structured quasilattices enable the dynamic coupling of vibrationally-induced dipole moments to produce optical dispersion and transverse optical-longitudinal optical (TO-LO) splitting of vibrational modes of the ionic liquid. According to dipolar coupling theory, the degree of TO-LO splitting is predicted to have a linear dependence on the number density of the ionic liquid. Both temperature and pressure will affect the number density of the ionic liquid and, therefore, the amount of TO-LO splitting for this mode. Therefore, we test these relationships through temperature- and pressure-dependent FT-IR spectroscopic studies of [C4mim]CF3SO3, focusing on the totally symmetric Ssbnd O stretching mode for the anion, νs(SO3). Increased temperature decreases the amount of TO-LO splitting for νs(SO3), whereas elevated pressure is found to increase the amount of band splitting. In both cases, the experimental observations follow the general predictions of dipolar coupling theory, thereby supporting the quasilattice model for this ionic liquid.
Existence of the dielectric constant in dipolar fluid mixtures
International Nuclear Information System (INIS)
Ramshaw, J.D.; Hamer, N.D.
1981-01-01
The existence of the dielectric constant epsilon is investigated for fluid mixtures of rigid polar molecules. The investigation is performed using the functional-derivative formalism for mixtures, and is closely analogous to that previously carried out for pure dipolar fluids [J. Chem. Phys. 68, 5199 (1978)]. Sufficient conditions for the existence of epsilon are obtained in terms of the direct correlation function matrix c/sub alphabeta/(12). It is found that epsilon exists if c/sub alphabeta/(12) depends only on relative positions and orientations, and becomes asymptotic to -theta/sub alphabeta/(12)/kT at long range, where theta/sub alphabeta/(12) is the dipole--dipole potential between a molecule of species α and one of species β. An expression for epsilon in terms of the short-range total correlation function matrix emerges automatically from the development. This expression is equivalent to an earlier result obtained by a different method. Expressions for epsilon in terms of c/sub alphabeta/(12) are derived for axially symmetric molecules and for molecules of arbitrary symmetry. In the former case, the expression involves the inverse of an N/sub c/ x N/sub c/ matrix, where N/sub c/ is the number of components in the mixture. This expression facilitates the evaluation of epsilon in the mean spherical approximation. For molecules of arbitrary symmetry, the expression for epsilon in terms of c/sub alphabeta/(12) involves the inverse of an N/sub c/ x N/sub c/ supermatrix, each element of which is a 3 x 3 matrix
Spin interactions in Graphene-Single Molecule Magnets Hybrids
Cervetti, Christian; Rettori, Angelo; Pini, Maria Gloria; Cornia, Andrea; Repollés, Aña; Luis, Fernando; Rauschenbach, Stephan; Dressel, Martin; Kern, Klaus; Burghard, Marko; Bogani, Lapo
2014-03-01
Graphene is a potential component of novel spintronics devices owing to its long spin diffusion length. Besides its use as spin-transport channel, graphene can be employed for the detection and manipulation of molecular spins. This requires an appropriate coupling between the sheets and the single molecular magnets (SMM). Here, we present a comprehensive characterization of graphene-Fe4 SMM hybrids. The Fe4 clusters are anchored non-covalently to the graphene following a diffusion-limited assembly and can reorganize into random networks when subjected to slightly elevated temperature. Molecules anchored on graphene sheets show unaltered static magnetic properties, whilst the quantum dynamics is profoundly modulated. Interaction with Dirac fermions becomes the dominant spin-relaxation channel, with observable effects produced by graphene phonons and reduced dipolar interactions. Coupling to graphene drives the spins over Villain's threshold, allowing the first observation of strongly-perturbative tunneling processes. Preliminary spin-transport experiments at low-temperature are further presented.
Tuning magnetic ordering in a dipolar square-kite tessellation
Petersen, Charlotte F.; Farhan, Alan; Dhuey, Scott; Chen, Zuhuang; Alava, Mikko J.; Scholl, Andreas; van Dijken, Sebastiaan
2018-02-01
The potential application of artificial spin ice in magnetic nanodevices provides a strong drive to investigate different lattice geometries. Here, we combine components of a recently investigated artificial spin ratchet with components of the prototypical square lattice to form a geometrically frustrated artificial spin ice system where Ising-type nanomagnets are arranged onto a two-dimensional square-kite lattice. Using synchrotron-based photoemission electron microscopy, we explore moment configurations achieved in this lattice geometry. Following thermal annealing, we image how a variation of the relevant lattice parameter affects magnetic ordering in four-island squares and four-island vertices during cooling through the Blocking temperature. Depending on lattice spacing, both nearly uniform and disordered spin configurations are accessible in our samples. We show that the relative energies of the building blocks of the system, which are typically used to classify lattice configurations, are not predictive of the low energy states adopted by the experimental system. To understand magnetic ordering in the square-kite lattice, longer range interactions must be considered.
Semchyschyn, Darlene J; Macdonald, Peter M
2004-02-01
The effects of bilayer surface charge on the conformation of the phosphocholine group of phosphatidylcholine were investigated using a torsion angle analysis of quadrupolar and dipolar splittings in, respectively, (2)H and (13)C NMR spectra of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) labelled in the phosphocholine group with either deuterons (POPC-alpha-d(2), POPC-beta-d(2) and POPC-gamma-d(9)) or carbon-13 (POPC-alpha-(13)C and POPC-alphabeta-(13)C(2)) and incorporated into magnetically aligned bicelles containing various amounts of either the cationic amphiphile 1,2-dimyristoyl-3-trimethylammoniumpropane (DMTAP) or the anionic amphiphile 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG). Three sets of quadrupolar splittings, one from each of the three deuteron labelling positions, and three sets of dipolar splittings ((13)C(alpha)-(31)P, (13)C(alpha)-(13)C(beta), (13)C(beta)-(14)N), were measured at each surface charge, along with the (31)P residual chemical shift anisotropy. The torsion angle analysis assumed fast anisotropic rotation of POPC about its long molecular axis, thus projecting all NMR interactions onto that director axis of motion. Dipolar, quadrupolar and chemical shift anisotropies were calculated as a function of the phosphocholine internal torsion angles by first transforming into a common reference frame affixed to the phosphocholine group prior to motional averaging about the director axis. A comparison of experiment and calculation provided the two order parameters specifying the director orientation relative to the molecule, plus the torsion angles alpha(3), alpha(4) and alpha(5). Surface charge was found to have little effect on the torsion angle alpha(5) (rotations about C(alpha)-C(beta)), but to have large and inverse effects on torsion angles alpha(3) [rotations about P-O(11)] and alpha(4) [rotations about O(11)-C(alpha)], yielding a net upwards tilt of the P-N vector in the presence of cationic surface charge, and a
Quasi-one-dimensional spin-orbit- and Rabi-coupled bright dipolar Bose-Einstein-condensate solitons
Chiquillo, Emerson
2018-01-01
We study the formation of stable bright solitons in quasi-one-dimensional (quasi-1D) spin-orbit- (SO-) and Rabi-coupled two pseudospinor dipolar Bose-Einstein condensates (BECs) of 164Dy atoms in the presence of repulsive contact interactions. As a result of the combined attraction-repulsion effect of both interactions and the addition of SO and Rabi couplings, two kinds of ground states in the form of self-trapped bright solitons can be formed, a plane-wave soliton (PWS) and a stripe soliton (SS). These quasi-1D solitons cannot exist in a condensate with purely repulsive contact interactions and SO and Rabi couplings (no dipole). Neglecting the repulsive contact interactions, our findings also show the possibility of creating PWSs and SSs. When the strengths of the two interactions are close to each other, the SS develops an oscillatory instability indicating a possibility of a breather solution, eventually leading to its destruction. We also obtain a phase diagram showing regions where the solution is a PWS or SS.
Torsional Alfvén Waves in a Dipolar Magnetic Field
Nataf, H. C.; Tigrine, Z.; Cardin, P.; Schaeffer, N.
2017-12-01
The discovery of torsional Alfvén waves in the Earth's core (Gillet et al, 2010) is a strong motivation for investigating the properties of these waves. Here, we report on the first experimental study of such waves. Alfvén waves are difficult to excite and observe in liquid metals because of their high magnetic diffusivity. Nevertheless, we obtained clear signatures of such diffusive waves in our DTS experiment. In this setup, some 40 liters of liquid sodium are contained between a ro = 210 mm-radius stainless steel outer shell, and a ri = 74 mm-radius copper inner sphere. Both spherical boundaries can rotate independently around a common vertical axis. The inner sphere shells a strong permanent magnet, which produces a nearly dipolar magnetic field whose intensity falls from 175 mT at ri to 8 mT at ro in the equatorial plane. We excite Alfvén waves in the liquid sodium by applying a sudden jerk of the inner sphere. To study the effect of global rotation, which leads to the formation of geostrophic torsional Alfvén waves, we spin the experiment at rotation rates fo = fi up to 15 Hz. The Alfvén wave produces a clear azimuthal magnetic signal on magnetometers installed in a sleeve inside the fluid. We also probe the associated azimuthal velocity field using ultrasound Doppler velocimetry. Electric potentials at the surface of the outer sphere turn out to be very revealing as well. In parallel, we use the XSHELLS magnetohydrodynamics spherical code to model torsional Alfvén waves in the experimental conditions, and beyond. We explore both linear and non-linear regimes. We observe a strong excitation of inertial waves in the equatorial plane, where the wave transits from a region of strong magnetic field to a region dominated by rotation (see figure of meridian map of azimuthal velocity). These novel observations should help deciphering the dynamics of Alfvén waves in planetary cores.
Katsyuba, Sergey A.; Vener, Mikhail V.; Zvereva, Elena E.; Brandenburg, J. Gerit
2017-03-01
Two variants of density functional theory computations have been applied to characterization of hydrogen bonds of the 1-(2-hydroxylethyl)-3-methylimidazolium acetate ([C2OHmim][OAc]), i.e. with and without inclusion of dispersion interactions. A comparison of the results demonstrates that London dispersion interactions have very little impact on the energetical, geometrical, infrared spectroscopic and electron density parameters of charge-assisted intermolecular hydrogen bonds functioning both in the crystal of the [C2OHmim][OAc] and in the isolated [C2OHmim]+ [OAc]- ion pairs.
Does polar interaction influence medium viscosity? A computer ...
Indian Academy of Sciences (India)
Abstract. Molecular dynamics simulations of model liquids interacting via Lennard–Jones (L–J) and. Stockmayer (SM) interactions have been carried out to explore the effects of the longer-ranged dipole–dipole interaction on solvent viscosity and diffusion. Switching on of the dipolar interaction at a fixed density and tem-.
International Nuclear Information System (INIS)
Thews, R.L.
1986-01-01
The research reported includes: low energy quark-hadron dynamics; quark-gluon models for hadronic interactions, decays and structure; mathematical and physical properties of nonlinear sigma models, Yang-Mills theories, and Coulomb gases, which are of interest in both particle physics and condensed matter physics; statistical and dynamical aspects of hadronic multiparticle production. 28 refs
Wang, Y.; Nakatsukasa, K.; Rademaker, L.; Berlijn, T.; Johnston, S.
2016-05-01
Mono- and multilayer FeSe thin films grown on SrTiO3 and BiTiO3 substrates exhibit a greatly enhanced superconductivity over that found in bulk FeSe. A number of proposals have been advanced for the mechanism of this enhancement. One possibility is the introduction of a cross-interface electron-phonon (e-ph) interaction between the FeSe electrons and oxygen phonons in the substrates that is peaked in the forward scattering (small {q}) direction due to the two-dimensional nature of the interface system. Motivated by this, we explore the consequences of such an interaction on the superconducting state and electronic structure of a two-dimensional system using Migdal-Eliashberg (ME) theory. This interaction produces not only deviations from the expectations of conventional phonon-mediated pairing but also replica structures in the spectral function and density of states, as probed by angle-resolved photoemission spectroscopy, scanning tunneling microscopy/spectroscopy, and quasiparticle interference imaging. We also discuss the applicability of ME theory for a situation where the e-ph interaction is peaked at small momentum transfer and in the FeSe/STO system.
Czech Academy of Sciences Publication Activity Database
Johnston, S.; Monney, C.; Bisogni, V.; Zhou, K.J.; Kraus, R.; Behr, G.; Strocov, V.N.; Málek, Jiří; Drechsler, S.L.; Geck, J.; Schmitt, T.; van den Brink, J.
2016-01-01
Roč. 7, Feb (2016), 1-7, č. článku 10653. ISSN 2041-1723 Institutional support: RVO:68378271 Keywords : X-ray scattering * electron-lattice interactions * spin-chain cuprates * renormalization of charge- transfer energy Subject RIV: BE - Theoretical Physics Impact factor: 12.124, year: 2016
Finley, Adam J.; Matt, Sean P.
2018-02-01
During the lifetime of Sun-like or low-mass stars a significant amount of angular momentum is removed through magnetized stellar winds. This process is often assumed to be governed by the dipolar component of the magnetic field. However, observed magnetic fields can host strong quadrupolar and/or octupolar components, which may influence the resulting spin-down torque on the star. In Paper I, we used the MHD code PLUTO to compute steady-state solutions for stellar winds containing a mixture of dipole and quadrupole geometries. We showed the combined winds to be more complex than a simple sum of winds with these individual components. This work follows the same method as Paper I, including the octupole geometry, which not only increases the field complexity but also, more fundamentally, looks for the first time at combining the same symmetry family of fields, with the field polarity of the dipole and octupole geometries reversing over the equator (unlike the symmetric quadrupole). We show, as in Paper I, that the lowest-order component typically dominates the spin-down torque. Specifically, the dipole component is the most significant in governing the spin-down torque for mixed geometries and under most conditions for real stars. We present a general torque formulation that includes the effects of complex, mixed fields, which predicts the torque for all the simulations to within 20% precision, and the majority to within ≈5%. This can be used as an input for rotational evolution calculations in cases where the individual magnetic components are known.
Hwang, K.-J.; Goldstein, M. L.; Moore, T. E.; Walsh, B. M.; Baishev, D. G.; Moiseyev, A. V.; Shevtsov, B. M.; Yumoto, K.
2014-01-01
A case study is presented using measurements from the Cluster spacecraft and ground-based magnetometers that show a substorm onset propagating from the inner to outer plasma sheet. On 3 October 2005, Cluster, traversing an ion-scale current sheet at the near-Earth plasma sheet, detected a sudden enhancement of Bz, which was immediately followed by a series of flux rope structures. Both the local Bz enhancement and flux ropes propagated tailward. Approximately 5 min later, another Bz enhancement, followed by a large density decrease, was observed to rapidly propagate earthward. Between the two Bz enhancements, a significant removal of magnetic flux occurred, possibly resulting from the tailward moving Bz enhancement and flux ropes. In our scenario, this flux removal caused the magnetotail to be globally stretched so that the thinnest sheet formed tailward of Cluster. The thinned current sheet facilitated magnetic reconnection that quickly evolved from plasma sheet to lobe and generated the later earthward moving dipolarization front (DF) followed by a reduction in density and entropy. Ground magnetograms located near the meridian of Cluster's magnetic foot points show two-step bay enhancements. The positive bay associated with the first Bz enhancement indicates that the substorm onset signatures propagated from the inner to the outer plasma sheet, consistent with the Cluster observation. The more intense bay features associated with the later DF are consistent with the earthward motion of the front. The event suggests that current disruption signatures that originated in the near-Earth current sheet propagated tailward, triggering or facilitating midtail reconnection, thereby preconditioning the magnetosphere for a later strong substorm enhancement.
Mersbergen, Dick van; Wijnen, Jan W.; Engberts, Jan B.F.N.
1998-01-01
The second-order rate constants for the 1,3-dipolar cycloaddition of benzonitrile oxide (1) with various dipolarophiles (2a-e) were determined in aqueous media and in organic solvents to gain more insight into the influence of an aqueous medium on pericyclic reactions. 1,3-Dipolar cycloadditions
Directed tunneling of a prescribed number of dipolar bosons in shaken triple-well potentials
International Nuclear Information System (INIS)
Luo, Xiaobing; Yu, Xiaoguang; Wu, Donglan; Hu, Qianglin; Wang, Yueming; Guo, Yu; Chong, Guishu
2015-01-01
We propose a scheme for precise control of the tunneling dynamics of dipolar bosons in shaken triple-well potentials. In high-frequency regimes and under resonance conditions, we have analytically and numerically demonstrated that we can transport an a priori prescribed number of dipolar bosons along different pathways and in different directions by adjusting the driving parameters. These results extend the previous many-body selective coherent destruction of tunneling schemes for nondipolar bosons in double-well potentials (Gong et al 2009 Phys. Rev. Lett. 103 133002; Longhi 2012 Phys. Rev. A 86 044102), thus offering an efficient way to design long-range coherent quantum transportation. (paper)
1,3-Dipolar Cycloadditions of Diazo Compounds in the Presence of Azides.
Aronoff, Matthew R; Gold, Brian; Raines, Ronald T
2016-04-01
The diazo group has untapped utility in chemical biology. The tolerance of stabilized diazo groups to cellular metabolism is comparable to that of azido groups. However, chemoselectivity has been elusive, as both groups undergo 1,3-dipolar cycloadditions with strained alkynes. Removing strain and tuning dipolarophile electronics yields diazo group selective 1,3-dipolar cycloadditions that can be performed in the presence of an azido group. For example, diazoacetamide but not its azido congener react with dehydroalanine residues, as in the natural product nisin.
Ground-state candidate for the classical dipolar kagome Ising antiferromagnet
Chioar, I. A.; Rougemaille, N.; Canals, B.
2016-06-01
We have investigated the low-temperature thermodynamic properties of the classical dipolar kagome Ising antiferromagnet using Monte Carlo simulations, in the quest for the ground-state manifold. In spite of the limitations of a single-spin-flip approach, we managed to identify certain ordering patterns in the low-temperature regime and we propose a candidate for this unknown state. This configuration presents some intriguing features and is fully compatible with the extrapolations of the at-equilibrium thermodynamic behavior sampled so far, making it a very likely choice for the dipolar long-range ordered state of the classical kagome Ising antiferromagnet.
Spin correlations in Ho2Ti2O7: A dipolar spin ice system
DEFF Research Database (Denmark)
Bramwell, S.T.; Harris, M.J.; Hertog, B.C. den
2001-01-01
described by a nearest neighbor spin ice model and very accurately described by a dipolar spin ice model. The heat capacity is well accounted for by the sum of a dipolar spin ice contribution and an expected nuclear spin contribution, known to exist in other Ho(3+) salts. These results settle the question......The pyrochlore material Ho(2)Ti(2)O(7) has been suggested to show "spin ice" behavior. We present neutron scattering and specific heat results that establish unambiguously that Ho(2)Ti(2)O(7) exhibits spin ice correlations at low temperature. Diffuse magnetic neutron scattering is quite well...
Simulation of transverse beam splitting using time-dependent dipolar or quadrupolar kicks
Capoani, Federico
2017-01-01
Two simple systems with high relevance for accelerator physics have been studied in detail in the context of this Summer Student Project. These systems describe the motion under the influence of detuning with amplitude due to non-linear magnets and an external, time-dependent force of dipolar or quadrupolar nature.Two simple systems with high relevance for accelerator physics have been studied in detail in the context of this Summer Student Project. These systems describe the motion under the influence of detuning with amplitude due to non-linear magnets and an external, time-dependent force of dipolar or quadrupolar nature.
Czech Academy of Sciences Publication Activity Database
Vavrinská, A.; Zelinka, J.; Šebera, Jakub; Sychrovský, Vladimír; Fiala, R.; Boelens, R.; Sklenář, V.; Trantírek, L.
2016-01-01
Roč. 64, č. 1 (2016), s. 53-62 ISSN 0925-2738 R&D Projects: GA ČR GA13-27676S Grant - others:AV ČR(CZ) M200551205 Institutional support: RVO:61388963 Keywords : NMR * DFT calculations * spin-spin interactions * magnetic field Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.410, year: 2016 http://link.springer.com/article/10.1007/s10858-015-0005-x
Energy Technology Data Exchange (ETDEWEB)
Ongonwou, F., E-mail: fred.ongonwou@gmail.com [Département de Physique, Faculté des Sciences, Université des Sciences et Techniques de Masuku, B.P. 943 Franceville (Gabon); Tetchou Nganso, H.M., E-mail: htetchou@yahoo.com [Atoms and Molecules Laboratory, Centre for Atomic Molecular Physics and Quantum Optics (CEPAMOQ), Faculty of Science, University of Douala, P.O. Box 8580, Douala (Cameroon); Ekogo, T.B., E-mail: tekogo@yahoo.fr [Département de Physique, Faculté des Sciences, Université des Sciences et Techniques de Masuku, B.P. 943 Franceville (Gabon); Kwato Njock, M.G., E-mail: mkwato@yahoo.com [Atoms and Molecules Laboratory, Centre for Atomic Molecular Physics and Quantum Optics (CEPAMOQ), Faculty of Science, University of Douala, P.O. Box 8580, Douala (Cameroon)
2016-12-15
In this study we present a model that we have formulated in the momentum space to describe atoms interacting with intense laser fields. As a further step, it follows our recent theoretical approach in which the kernel of the reciprocal-space time-dependent Schrödinger equation (TDSE) is replaced by a finite sum of separable potentials, each of them supporting one bound state of atomic hydrogen (Tetchou Nganso et al. 2013). The key point of the model is that the nonlocal interacting Coulomb potential is expanded in a Coulomb Sturmian basis set derived itself from a Sturmian representation of Bessel functions of the first kind in the position space. As a result, this decomposition allows a simple spectral treatment of the TDSE in the momentum space. In order to illustrate the credibility of the model, we have considered the test case of atomic hydrogen driven by a linearly polarized laser pulse, and have evaluated analytically matrix elements of the atomic Hamiltonian and dipole coupling interaction. For various regimes of the laser parameters used in computations our results are in very good agreement with data obtained from other time-dependent calculations.
Ongonwou, F.; Tetchou Nganso, H. M.; Ekogo, T. B.; Kwato Njock, M. G.
2016-12-01
In this study we present a model that we have formulated in the momentum space to describe atoms interacting with intense laser fields. As a further step, it follows our recent theoretical approach in which the kernel of the reciprocal-space time-dependent Schrödinger equation (TDSE) is replaced by a finite sum of separable potentials, each of them supporting one bound state of atomic hydrogen (Tetchou Nganso et al. 2013). The key point of the model is that the nonlocal interacting Coulomb potential is expanded in a Coulomb Sturmian basis set derived itself from a Sturmian representation of Bessel functions of the first kind in the position space. As a result, this decomposition allows a simple spectral treatment of the TDSE in the momentum space. In order to illustrate the credibility of the model, we have considered the test case of atomic hydrogen driven by a linearly polarized laser pulse, and have evaluated analytically matrix elements of the atomic Hamiltonian and dipole coupling interaction. For various regimes of the laser parameters used in computations our results are in very good agreement with data obtained from other time-dependent calculations.
Onda, Ken; Ogihara, Sho; Yonemitsu, Kenji; Maeshima, Nobuya; Ishikawa, Tadahiko; Okimoto, Yoichi; Shao, Xiangfeng; Nakano, Yoshiaki; Yamochi, Hideki; Saito, Gunzi; Koshihara, Shin-Ya
2008-08-01
The quasistable state in the photoinduced phase transition for the quasi-one-dimensional quarter-filled organic conductor (EDO-TTF)2PF6 has been examined by ultrafast reflective measurements and time-dependent model calculations incorporating both electron-electron and electron-phonon interactions. The transient optical conductivity spectrum over a wide probe photon-energy range revealed that photoexcitation induced a new type of charge-disproportionate state. Additionally, coherent and incoherent oscillations dependent on probe photon energies were found, as predicted by the calculation.
Strong-strong beam-beam simulation on parallel computer
Energy Technology Data Exchange (ETDEWEB)
Qiang, Ji
2004-08-02
The beam-beam interaction puts a strong limit on the luminosity of the high energy storage ring colliders. At the interaction points, the electromagnetic fields generated by one beam focus or defocus the opposite beam. This can cause beam blowup and a reduction of luminosity. An accurate simulation of the beam-beam interaction is needed to help optimize the luminosity in high energy colliders.