On the Dirac equation for a quark
Pestov, I B
2003-01-01
It is argued from geometrical, group-theoretical and physical points of view that in the framework of QCD it is not only necessary but also possible to modify the Dirac equation so that correspondence principle holds valid. The Dirac wave equation for a quark is proposed and some consequences are considered. In particular, it is shown that interquark potential expresses the Coulomb law for the quarks and, in fact, coincides with the known Cornell potential.
Energy Technology Data Exchange (ETDEWEB)
Karbstein, Felix
2009-07-08
We introduce a new method for dealing with fermionic quantum field theories amenable to a mean-field-type approximation. In this work we focus on the relativistic Hartree approximation. Our aim is to integrate out the Dirac sea and derive a no-sea effective theory'' with positive energy single particle states only. As the derivation of the no-sea effective theory involves only standard Feynman diagrams, our approach is quite general and not restricted to particular space-time dimensions. We develop and illustrate the approach in the ''large N'' limit of the Gross-Neveu model family in 1+1 dimensions. As the Gross-Neveu model has been intensely studied and several analytical solutions are known for this model, it is an ideal testing ground for our no-sea effective theory approach. The chiral Gross-Neveu model, also referred to as 1+1 dimensional Nambu-Jona-Lasinio model, turns out to be of particular interest. In this case, we explicitly derive a consistent effective theory featuring both elementary ''{pi} meson'' fields and (positive energy) ''quark'' fields, starting from a purely fermionic quantum field theory. In the second part of this work, we apply our approach to the Walecka model in 1+1 and 3+1 dimensions. As the Dirac sea caused considerable difficulties in attempts to base nuclear physics on field theoretic models like the Walecka model, mean-field calculations were typically done without the sea. We confront several of these mean-field theory results with our no-sea effective theory approach. The potential of our approach is twofold. While the no-sea effective theory can be utilized to provide new analytical insights in particular parameter regimes, it also sheds new light on more fundamental issues as the explicit emergence of effective, Dirac-sea induced multi-fermion interactions in an effective theory with positive energy states only. (orig.)
Volfson, Boris
2013-09-01
The hypothesis of transition from a chaotic Dirac Sea, via highly unstable positronium, into a Simhony Model of stable face-centered cubic lattice structure of electrons and positrons securely bound in vacuum space, is considered. 13.75 Billion years ago, the new lattice, which, unlike a Dirac Sea, is permeable by photons and phonons, made the Universe detectable. Many electrons and positrons ended up annihilating each other producing energy quanta and neutrino-antineutrino pairs. The weak force of the electron-positron crystal lattice, bombarded by the chirality-changing neutrinos, may have started capturing these neutrinos thus transforming from cubic crystals into a quasicrystal lattice. Unlike cubic crystal lattice, clusters of quasicrystals are "slippery" allowing the formation of centers of local torsion, where gravity condenses matter into galaxies, stars and planets. In the presence of quanta, in a quasicrystal lattice, the Majorana neutrinos' rotation flips to the opposite direction causing natural transformations in a category comprised of three components; two others being positron and electron. In other words, each particle-antiparticle pair "e-" and "e+", in an individual crystal unit, could become either a quasi- component "e- ve e+", or a quasi- component "e+ - ve e-". Five-to-six six billion years ago, a continuous stimulation of the quasicrystal aetherial lattice by the same, similar, or different, astronomical events, could have triggered Hebbian and anti-Hebbian learning processes. The Universe may have started writing script into its own aether in a code most appropriate for the quasicrystal aether "hardware": Eight three-dimensional "alphabet" characters, each corresponding to the individual quasi-crystal unit shape. They could be expressed as quantum Turing machine qubits, or, alternatively, in a binary code. The code numerals could contain terminal and nonterminal symbols of the Chomsky's hierarchy, wherein, the showers of quanta, forming the
Effects of Dirac's Negative Energy Sea on Quantum Numbers
Jackiw, R.
1999-01-01
One route towards understanding both fractional charges and chiral anomalies delves into Dirac's negative energy sea. Usually we think of Dirac's negative energy sea as an unphysical construct, invented to render quantum field theory physically acceptable by hiding the negative energy solutions. I suggest that in fact physical consequences can be drawn from Dirac's construction.
Physics of the nucleon sea quark distributions
Energy Technology Data Exchange (ETDEWEB)
Vogt, R.
2000-03-10
Sea quark distributions in the nucleon have naively been expected to be generated perturbatively by gluon splitting. In this case, there is no reason for the light quark and anti-quark sea distributions to be different. No asymmetries in the strange or heavy quark sea distributions are predicted in the improved parton model. However,recent experiments have called these naive expectations into question. A violation of the Gottfried sum rule has been measured in several experiments, suggesting that (bar u) < (bar d) in the proton. Additionally, other measurements, while not definitive, show that there may be an asymmetry in the strange and anti-strange quark sea distributions. These effects may require nonperturbative explanations. In this review we first discuss the perturbative aspects of the sea quark distributions. We then describe the experiments that could point to nonperturbative contributions to the nucleon sea. Current phenomenological models that could explain some of these effects are reviewed.
SU(2) Dirac-Yang-Mills quantum mechanics of spatially constant quark and gluon fields
Pavel, H -P
2011-01-01
The quantum mechanics of spatially constant SU(2) Yang-Mills- and Dirac-fields minimally coupled to each other is investigated as the strong coupling limit of 2-color-QCD. Using a canonical transformation of the quark and gluon fields, which Abelianises the Gauss law constraints to be implemented, the corresponding unconstrained Hamiltonian and total angular momentum are derived. In the same way as this reduces the colored spin-1 gluons to unconstrained colorless spin-0 and spin-2 gluons, it reduces the colored spin-1/2 quarks to unconstrained colorless spin-0 and spin-1 quarks. These however continue to satisfy anti-commutation relations and hence the Pauli-exclusion principle. The obtained unconstrained Hamiltonian is then rewritten into a form, which separates the rotational from the scalar degrees of freedom. In this form the low-energy spectrum can be obtained with high accuracy. As an illustrative example, the spin-0 energy-spectrum of the quark-gluon system is calculated for massless quarks of one flav...
Dirac sea effects in $K^+$ scattering from nuclei
Caillon, J C
1993-01-01
The ratio $R_T$ of $K^+-^{12}C$ to $K^+-d$ cross sections has been calculated microscopically using a boson-exchange $KN$ amplitude in which the $\\sigma$ and $\\omega$ mesons are dressed by the modifications of the Dirac sea in nuclear matter. In spite of the fact that this dressing leads to a scaling of the mesons effective mass in nuclear matter, the effect on the $R_T$ ratio is found to be weak.
Energy Technology Data Exchange (ETDEWEB)
Barik, N.; Das, M.
1983-12-01
The effect of confinement on the magnetic moment of a quark has been studied in a simple independent-quark model based on the Dirac equation with a power-law potential. The magnetic moments so obtained for the constituent quarks, which are found to be significantly different from their corresponding Dirac moments, are used in predicting the magnetic moments of baryons in the nucleon octet as well as those in the charmed and b-flavored sectors. We not only get an improved result for the proton magnetic moment, but the calculation for the rest of the nucleon octet also turns out to be in reasonable agreement with experiment. The overall predictions for the charmed and b-flavored baryons are also comparable with other model predictions.
Kanazawa, Takuya
2016-01-01
We study the interplay between the Kondo effect and (color) superconductivity in doped Dirac metals with magnetic impurities and in quark matter with colorful impurities. We first point out that the overscreened Kondo effect arises in the normal state of these systems. Next the (color) superconducting gap is incorporated as a mean field and the phase diagram for a varying gap and temperature is constructed nonperturbatively. A rich phase structure emerges from a competition of effects unique to a multichannel system. The Kondo-screened phase is shown to disappear for a sufficiently large gap. Peculiarity of quark matter due to the confining property of non-Abelian gauge fields is noted. We also investigate the spectrum of sub-gap excited states, called Shiba states. Based on a model calculation and physical reasoning we predict that, as the coupling of the impurity to the bulk is increased, there will be more than one quantum phase transition due to level crossing among overscreened states.
Quark mass anomalous dimension from the twisted mass Dirac operator spectrum
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Cichy, Krzysztof [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Poznan Univ. (Poland). Faculty of Physics
2013-12-15
We investigate whether it is possible to extract the quark mass anomalous dimension and its scale dependence from the spectrum of the twisted mass Dirac operator in Lattice QCD. The answer to this question appears to be positive, provided that one goes to large enough eigenvalues, sufficiently above the non-perturbative regime. The obtained results are compared to continuum perturbation theory. By analyzing possible sources of systematic effects, we find the domain of applicability of the approach, extending from an energy scale of around 1.5 to 4 GeV. The lower limit is dictated by physics (non-perturbative effects at low energies), while the upper bound is set by the ultraviolet cut-off of present-day lattice simulations. We use gauge field configuration ensembles generated by the European Twisted Mass Collaboration (ETMC) with 2 flavours of dynamical twisted mass quarks, at 4 lattice spacings in the range between around 0.04 and 0.08 fm.
Quark sea asymmetry of the nucleon
Mírez, Carlos; Tomio, Lauro; Trevisan, L. A.; Frederico, T.
2010-02-01
The light anti-quark and quark distribution in the proton, as well as the neutron to proton ratio of the structure functions, extracted from experimental data, are well fitted by a statistical model of linear-confined quarks. The parameters of the model are given by a temperature, which is adjusted by the Gottfried sum-rule violation, and two chemical potentials given by the corresponding up ( u) and down ( d) quark normalizations in the nucleon. The quark energy levels are generated by a relativistic linear-confined scalar plus vector potential.
Akemann, G; Bloch, J; Shifrin, L; Wettig, T
2008-01-25
We analyze how individual eigenvalues of the QCD Dirac operator at nonzero quark chemical potential are distributed in the complex plane. Exact and approximate analytical results for both quenched and unquenched distributions are derived from non-Hermitian random matrix theory. When comparing these to quenched lattice QCD spectra close to the origin, excellent agreement is found for zero and nonzero topology at several values of the quark chemical potential. Our analytical results are also applicable to other physical systems in the same symmetry class.
Phases of SU(3) Gauge Theories with Fundamental Quarks via Dirac Spectral Density
Alexandru, Andrei
2015-01-01
We suggest that gauge interactions of SU(3) gluons and fundamental quarks produce three distinct types of infrared behavior in Dirac spectral density $\\rho(\\lambda, V \\to \\infty)$ (Fig.1), effectively labeling three types of dynamical phases occurring in these theories. The two monotonic (standard) cases entail confinement with chiral symmetry breaking and the lack of both, respectively. The bimodal (anomalous) option signifies deconfined phase with broken chiral symmetry. This generalization rests on the following. $(\\alpha)$ We show, via numerical simulation, that previously observed bimodal behavior in N$_f$=0 theory past deconfinement temperature $T_c$ is stable with respect to both infrared and ultraviolet cutoffs, concluding that this prototypical anomalous phase indeed exists. The width of the anomalous peak while small (few MeV at $T/T_c=1.12$), is non-zero in the infinite-volume limit. $(\\beta)$ We show in detail that transition to bimodal $\\rho(\\lambda)$ in N$_f$=0 coincides with Z$_3$ deconfinement...
Results from overlap valence quarks on a twisted mass sea
Garron, N
2007-01-01
We present results of lattice computations using overlap fermions on a twisted mass background. $N_f=2$ full QCD gauge configurations have been produced by the ETM Collaboration with very light pions (down to less than 300 MeV), with small lattice spacing ($a \\approx 0.09$ fm) and large volumes ($V/a^4=24^3\\times 48$). By profiting of the good chiral properties of the overlap operator for the valence quarks, it is also possible to have a precise (and unquenched) determination of those physical quantities where the chiral properties are crucial. In order to have unquenched results, we match the valence quark mass with the sea quark mass. We also perform computations with different quark masses in order to simulate (partially quenched) Strange and Charm quarks. A typical application is the computation of $B_K$, for which we present first results.
Karbstein, Felix
2007-01-01
We use 1+1 dimensional large N Gross-Neveu models as a laboratory to derive microscopically effective Lagrangians for positive energy fermions only. When applied to baryons, the Euler-Lagrange equation for these effective theories assumes the form of a non-linear Dirac equation. Its solution reproduces the full semi-classical results including the Dirac sea to any desired accuracy. Dynamical effects from the Dirac sea are encoded in higher order derivative terms and multi-fermion interactions with perturbatively calculable, finite coefficients. Characteristic differences between models with discrete and continuous chiral symmetry are observed and clarified.
Scaling behavior and sea quark dependency of pion spectrum
Adams, D; Kim, H J; Kim, J; Kim, K; Yoon, B; Lee, W; Jung, C; Sharpe, S R
2008-01-01
We study the pion spectrum (and in particular taste-symmetry breaking within it) using HYP-smeared valence staggered fermions on the coarse and fine MILC lattices (which have asqtad staggered sea quarks). We focus on the dependence on lattice spacing and sea-quark mass. We also update our results on source dependence. Our main conclusion is that on the MILC fine lattices the appropriate power-counting for SU(3) staggered chiral perturbation theory may have discretization errors entering at next-to-leading order rather than at leading-order.
Effects of heavy sea quarks at low energies.
Bruno, Mattia; Finkenrath, Jacob; Knechtli, Francesco; Leder, Björn; Sommer, Rainer
2015-03-13
We present a factorization formula for the dependence of light hadron masses and low energy hadronic scales on the mass M of a heavy quark: apart from an overall mass-independent factor Q, ratios such as r_{0}(M)/r_{0}(0) are computable in perturbation theory at large M. The perturbation theory part is stable concerning different loop orders. Our nonperturbative Monte Carlo results obtained in a model calculation, where a doublet of heavy quarks is decoupled, match quantitatively to the perturbative prediction. Upon taking ratios of different hadronic scales at the same mass, the perturbative function drops out and the ratios are given by the decoupled theory up to M^{-2} corrections. We verify-in the continuum limit-that the sea quark effects of quarks with masses around the charm mass are very small in such ratios.
Alexandru, Andrei
2014-01-01
The validity of recently proposed equivalence between valence spontaneous chiral symmetry breaking (vSChSB) and chiral polarization of low energy Dirac spectrum (ChP) in SU(3) gauge theory, is examined for the case of twelve mass-degenerate fundamental quark flavors. We find that the vSChSB-ChP correspondence holds for regularized systems studied. Moreover, our results suggest that vSChSB occurs in two qualitatively different circumstances: there is a quark mass $m_c$ such that for $m > m_c$ the mode condensing Dirac spectrum exhibits standard monotonically increasing density, while for $m_{ch} < m < m_c$ the peak around zero separates from the bulk of the spectrum, with density showing a pronounced depletion at intermediate scales. Valence chiral symmetry restoration may occur at yet smaller masses $m < m_{ch}$, but this has not yet been seen by overlap valence probe, leaving the $m_{ch}=0$ possibility open. The latter option could place massless N$_f$=12 theory outside of conformal window. Anomalou...
Sea quark transverse momentum distributions and dynamical chiral symmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Schweitzer, Peter [Univ. of Connecticut, Storrs, CT (United States); Strikman, Mark [Penn State Univ., State College, PA (United States); Weiss, Christian [JLAB Newport News, VA (United States)
2014-01-01
Recent theoretical studies have provided new insight into the intrinsic transverse momentum distributions of valence and sea quarks in the nucleon at a low scale. The valence quark transverse momentum distributions (q - qbar) are governed by the nucleon's inverse hadronic size R{sup -1} ~ 0.2 GeV and drop steeply at large p{sub T}. The sea quark distributions (qbar) are in large part generated by non-perturbative chiral-symmetry breaking interactions and extend up to the scale rho{sup -1} ~ 0.6 GeV. These findings have many implications for modeling the initial conditions of perturbative QCD evolution of TMD distributions (starting scale, shape of p{sub T}. distributions, coordinate-space correlation functions). The qualitative difference between valence and sea quark intrinsic p{sub T}. distributions could be observed experimentally, by comparing the transverse momentum distributions of selected hadrons in semi-inclusive deep-inelastic scattering, or those of dileptons produced in pp and pbar-p scattering.
A beautiful sea: P. A. M. Dirac's epistemology and ontology of the vacuum.
Wright, Aaron Sidney
2016-07-01
This paper charts P.A.M. Dirac's development of his theory of the electron, and its radical picture of empty space as an almost-full plenum. Dirac's Quantum Electrodynamics famously accomplished more than the unification of special relativity and quantum mechanics. It also accounted for the 'duplexity phenomena' of spectral line splitting that we now attribute to electron spin. But the extra mathematical terms that allowed for spin were not alone, and this paper charts Dirac's struggle to ignore or account for them as a sea of strange, negative-energy, particles with positive 'holes'. This work was not done in solitude, but rather in exchanges with Dirac's correspondence network. This social context for Dirac's work contests his image as a lone genius, and documents a community wrestling with the ontological consequences of their work. Unification, consistency, causality, and community are common factors in explanations in the history of physics. This paper argues on the basis of materials in Dirac's archive that --- in addition --- mathematical beauty was an epistemological factor in the development of the electron and hole theory. In fact, if we believe that Dirac's beautiful mathematics captures something of the world, then there is both an epistemology and an ontology of mathematical beauty.
Light quark flavor asymmetry in the nucleon sea
Tadepalli, Arun
2016-09-01
SeaQuest E906 is an experiment aimed at studying the anti-quark distributions in the nucleon and nuclei. The experiment uses a 120 GeV proton beam extracted from the Main Injector at Fermilab to collide with various targets of hydrogen, deuterium, carbon, iron and tungsten to study a variety of physics topics. It takes advantage of the Drell-Yan process to probe the nucleon sea structure. In the Drell-Yan process, a quark from one hadron annihilates with an anti-quark from another hadron, producing a virtual photon which eventually decays into a dilepton pair. The SeaQuest forward spectrometer is optimized for detecting such di-muons. Comparison of Drell-Yan cross-section ratios of liquid hydrogen and deuterium allows SeaQuest to probe the d (x) / u (x) ratio up to a region of 0.45 in Bjorken-x, a region which hasn't been explored yet. Preliminary analysis of data sets will be presented in the talk.
Probing Sea Quark and Gluon Polarization at STAR
Stevens, Justin R
2014-01-01
One of the primary goals of the spin program at the Relativistic Heavy Ion Collider (RHIC) is to determine the polarization of the sea quarks and gluons in the proton. The polarization of the sea quarks is probed through the production of $W^{-(+)}$ bosons via the annihilation of $\\bar{u}+d\\,(\\bar{d}+u)$, at leading order. In this proceedings we report measurements of the single-spin asymmetry, $A_{L}$, for $W$ boson production at $\\sqrt{s} = 510$ GeV, and the new constraints these results place on the antiquark helicity distributions. Recent results on the longitudinal double-spin asymmetry, $A_{LL}$, for inclusive and di-jet production at $\\sqrt{s} = 200$ GeV are also presented. The inclusive jet results provide the first experimental indication of non-zero gluon polarization in the $x$ range probed at RHIC.
Ohno, H; Karsch, F; Mukherjee, S
2011-01-01
We report on the behavior of the eigenvalue distribution of the Dirac operator in (2+1)-flavor QCD at finite temperature, using the HISQ action. We calculate the eigenvalue density at several values of the temperature close to the pseudocritical temperature. For this study we use gauge field configurations generated on lattices of size $32^3 \\times 8$ with two light quark masses corresponding to pion masses of about 160 and 115 MeV. We find that the eigenvalue density below $T_c$ receives large contributions from near-zero modes which become smaller as the temperature increases or the light quark mass decreases. Moreover we find no clear evidence for a gap in the eigenvalue density up to 1.1$T_c$. We also analyze the eigenvalue density near $T_c$ where it appears to show a power-law behavior consistent with what is expected in the critical region near the second order chiral symmetry restoring phase transition in the massless limit.
Studies of the Strange Sea-Quarks Spin with Kaons
Benmokhtar, Fatiha; Voloshin, Andrew; Goodwill, Justin; Lendacky, Andrew
2017-01-01
It is well known that quarks and gluons give the substructure to the nucleons. and understanding of the spin structure of the nucleon in terms of quarks and gluons has been the goal of intense investigations during the last decades. The determination of strangeness is challenging and the only way of determining the strange distribution accurately from data is to improve the semi-inclusive information. This talk is focused on the determination of the strange sea contribution to the nucleon spin through the pseudo-scalar method using semi-inclusive Kaon detection technique with CLAS12 at Jefferson Lab. A Ring Imaging CHerenkov (RICH) detector is under construction and will be used for pion-kaon-proton separation. National Science Foundation #1615067.
Institute of Scientific and Technical Information of China (English)
DUAN Chun-Gui; LIU Na
2009-01-01
By means of two typical kinds of quark energy loss parametrization and the nuclear parton distribu-tions determined only with lepton-nuclear deep inelastic scattering experimental data, a leading order analysis is performed on the proton-induced Drell-Yau differential cross section ratios of tungsten versus deuterium as a function of the quark momentum fraction in the beam proton and target nuclei. It is found that the theoretical results with quark energy loss are in good agreement with the experimental data. The quark energy loss effect produces approximately 3% to 11% suppression on the Drell-Yan differential cross section ratios RW/D in the range 0.05 ≤ x2≤ 0.3. The application of nuclear Drell-Yan data with heavy targets is remarkably subject to difficulty in the constraint of the nuclear sea quark distribution.
The Physical Foundation of the Quark Model the Quark Model as an approximation of the BCC Model
Xu, J L
2001-01-01
From the Dirac sea concept, the BCC model infers that the quarks u and d constitute a body center cubic quark lattice in the vacuum; when a quark $q^*$ is excited from the vacuum, the nearest primitive cell u' and d' is accompanying excited by the quark $q^*$. Using the energy band theory, the model deduces the quantum numbers (I, S, C, b, and Q) and the masses of all quarks using a united mass formula. Then, it shows that the system of} 3 excited quarks ($q^*u'd'
Testing mixed action approaches to meson spectroscopy with twisted mass sea quarks
Berlin, Joshua; Wagner, Marc
2013-01-01
We explore and compare three mixed action setups with Wilson twisted mass sea quarks and different valence quark actions: (1) Wilson twisted mass, (2) Wilson twisted mass + clover and (3) Wilson + clover. Our main goal is to reduce lattice discretization errors in mesonic spectral quantities, in particular to reduce twisted mass parity and isospin breaking.
A kT-dependent sea-quark density for the CASCADE Monte Carlo event generator
Hautmann, F; Jung, H
2012-01-01
Parton-shower event generators that go beyond the collinear-ordering approximation at small x have so far included only gluon and valence quark channels at transverse momentum dependent level. We describe results of recent work to include effects of the sea-quark distribution with explicit dependence on the transverse quark-momentum.This sea-quark density is then applied to the description of forward Z -production. The qq*->Z matrix element (with one off-shell quark) is calculated in an explicit gauge invariant way, making use of high energy factorization. The kT-factorized result has been implemented into the CCFM Monte-Carlo CASCADE and a numerical comparison with the qg*->Zq matrix element has been carried out.
Flavor asymmetry of the nucleon sea and the five-quark components of the nucleons.
Chang, Wen-Chen; Peng, Jen-Chieh
2011-06-24
The existence of the five-quark Fock states for the intrinsic charm quark in the nucleons was suggested some time ago, but conclusive evidence is still lacking. We generalize the previous theoretical approach to the light-quark sector and study possible experimental signatures for such five-quark states. In particular, we compare the d-ū and ū + d-s-s data with the calculations based on the five-quark Fock states. The qualitative agreement between the data and the calculations is interpreted as evidence for the existence of the intrinsic light-quark sea in the nucleons. The probabilities for the |uuduū and |uuddd Fock states are also extracted.
Gell-Mann, M.
In these lectures I want to speak about at least two interpretations of the concept of quarks for hadrons and the possible relations between them. First I want to talk about quarks as "constituent quarks". These were used especially by G. Zweig (1964) who referred to them as aces. One has a sort of a simple model by which one gets elementary results about the low-lying bound and resonant states of mesons and baryons, and certain crude symmetry properties of these states, by saying that the hadrons act as if they were made up of subunits, the constituent quarks q. These quarks are arranged in an isotopic spin doublet u, d and an isotopic spin singlet s, which has the same charge as d and acts as if it had a slightly higher mass…
Physical and cut-off effects of heavy sea quarks
Knechtli, Francesco; Bruno, Mattia; Finkenrath, Jacob; Leder, Björn; Marinkovic, Marina; Sommer, Rainer
2014-01-01
We simulate a theory with two dynamical O($a$) improved Wilson quarks whose mass $M$ ranges from a factor eight up to a factor two below the charm quark mass and at three values of the lattice spacing ranging from 0.066 to 0.034 fm. This theory is a prototype to study the decoupling of heavy quarks. We measure the mass and cut-off dependence of ratios of gluonic observables defined from the Wilson flow or the static potential. The size of the 1/$M$ corrections can be determined and disentangled from the lattice artifacts. The difference with the pure gauge theory is at the percent level when two quarks with a mass of the charm quark are present.
Convergence for Imaginary Time Step evolution in the Fermi and Dirac seas
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
The convergence for the Imaginary Time Step (ITS) evolution with time step is investigated by performing the ITS evolution for the Schrdinger-like equation and the charge-conjugate Schrdinger-like equation deduced from Dirac equation for the single proton levels of 12C in both the Fermi and Dirac seas. For the guaranteed convergence of the ITS evolution to the "exact" results,the time step should be smaller than a "critical" time step Δtc for a given single-particle level. The "critical" time step Δtc is more sensitive to the quantum numbers |κ| than to the energy of the single-particle level. For the single-particle levels with the same κ,their "critical" time steps are in the same order. For the single-particle levels with similar energy,a relatively small (large) "critical" time step for larger (smaller) |κ| is needed. These conclusions can be used in the future self-consistent calculation to optimize the evolution procedure.
A persistent particle ontology for QFT in terms of the Dirac sea
Deckert, Dirk-Andre; Oldofredi, Andrea
2016-01-01
We show that the Bohmian approach in terms of persisting particles that move on continuous trajectories following a deterministic law can be literally applied to QFT. By means of the Dirac sea model -- exemplified in the electron sector of the standard model neglecting radiation -- we explain how starting from persisting particles, one is led to standard QFT employing creation and annihilation operators when tracking the dynamics with respect to a reference state, the so-called vacuum. Since on the level of wave functions, both formalisms are mathematically equivalent, this proposal provides for an ontology of QFT that includes a dynamics of individual processes, solves the measurement problem and explains the appearance of creation and annihilation events.
Can sea quark asymmetry shed light on the orbital angular momentum of the proton?
Nocera, Emanuele R
2016-01-01
A striking prediction of several extensions of the constituent quark model, including the unquenched quark model, the pion cloud model and the chiral quark model, is a proportionality relationship between the quark sea asymmetry and the orbital angular momentum of the proton. We investigate to which extent a relationship of this kind is corroborated by the experiment, through a systematic comparison between expectations based on models and predictions obtained from a global analysis of hard-scattering data in perturbative Quantum Chromodynamics. We find that the data allows the angular momentum of the proton to be proportional to its sea asymmetry, though with a rather large range of the optimal values of the proportionality coefficient. Typical values do not enable us to discriminate among expectations based on different models. In order to make our comparison conclusive, the extrapolation uncertainties on the proportionality coefficient should be reduced, hopefully by means of accurate measurements in the r...
Exploring Light Anti-quark Asymmetry with the SeaQuest Experiment
Qu, Zhongming
2012-10-01
The Fermilab E906/SeaQuest experiment measures the anti-quark structure of the nucleon which eventually will give unique insight into the origin of the sea quarks. The predecessor E866/NuSea experiment showed a clear asymmetry of the ratio for Bjorken x0.25, indicating clear deviations from the phenomenological models. The E906/SeaQuest experiment will measure the Drell-Yan cross section in p-p and p-d scattering and will determine the d/u asymmetry over 0.04event rate by factor of 50 compared to E866. This will significantly improve the statistics during the expected two-year run from early 2013 to Dec 2014. The scientific motivation as well as the current status, primarily the design, performance, and the future improvements of the current cryogenic targets will be presented. The expected results from E906/SeaQuest experiment will also be addressed.
On the effects of heavy sea quarks at low energies
Bruno, Mattia; Knechtli, Francesco; Leder, Bjoern; Sommer, Rainer
2014-01-01
We present a factorisation formula for the dependence of light hadron masses and low energy hadronic scales on the mass $M$ of a heavy quark: apart from an overall factor $Q$, ratios such as $r_0(M)/r_0(0)$ are computable in perturbation theory at large $M$. The mass-independent factor $Q$ is obtained from the theory in the limit $M\\to0$ and the decoupled theory with the heavy quark removed. The perturbation theory part is stable concerning different loop orders and our non-perturbative results match on quantitatively to the perturbative prediction. Upon taking ratios of different hadronic scales at the same mass, the perturbative function drops out and the ratios are given by the decoupled theory up to $M^{-2}$ corrections. Our present numerical results are obtained in a model calculation where there are no light quarks and a heavy doublet of quarks is decoupled. They are limited to masses a factor two below the charm. This is not large enough to see the $M^{-2}$ scaling predicted by the theory, but it is su...
TMD PDFs. A Monte Carlo implementation for the sea quark distribution
Energy Technology Data Exchange (ETDEWEB)
Hautmann, F. [Oxford Univ. (United Kingdom). Dept. of Theoretical Physics; Hentschinski, M. [Univ. Autonoma de Madrid (Spain). Dept. Fisica Teorica UAM/CSIC; Jung, H. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); European Organization for Nuclear Research (CERN), Geneva (Switzerland)
2012-05-15
This article gives an introduction to transverse momentum dependent (TMD) parton distribution functions and their use in shower Monte Carlo event generators for high-energy hadron collisions, and describes recent progress in the treatment of sea quark effects within a TMD parton-shower framework.
Gluons and the quark sea at high energies : distributions, polarization, tomography
Boer, D.; Diehl, M.; Milner, R.; Venugopalan, R.; Vogelsang, W.; Accardi, A.; Aschenauer, E.; Burkardt, M.; Ent, R.; Guzey, V.; Hasch, D.; Kumar, K.; Lamont, M. A. C.; Li, Y.; Marciano, W. J.; Marquet, C.; Sabatie, F.; Stratmann, M.; Yuan, F.; Abeyratne, S.; Ahmed, S.; Aidala, C.; Alekhin, S.; Anselmino, M.; Avakian, H.; Bacchetta, A.; Bartels, J.; H., BC; Beebe-Wang, J.; Belomestnykh, S.; Ben-Zvi, I.; Beuf, G.; Blumlein, J.; Blaskiewicz, M .; Bogacz, A.; Brodsky, S. J.; Burton, T.; Calaga, R.; Chang, X.; Cherednikov, I. O.; Chevtsov, P.; Chirilli, G. A.; Atti, C. Ciofi degli; Cloet, I. C.; Cooper-Sarkar, A.; Debbe, R.; Derbenev, Ya; Deshpande, A.; Dominguez, F.; Dumitru, A.; Dupre, R.; Erdelyi, B.; Faroughy, C.; Fazio, S.; Fedotov, A.; Forshaw, J. R.; Geraud, R.; Gallmeister, K.; Gamberg, L.; Gao, J. -H.; Gassner, D.; Gelis, F.; Gilfoyle, G. P.; Goldstein, G.; Golec-Biernat, K.; Goncalves, V. P.; Gonderinger, M.; Guzzi, M.; Hagler, P.; Hahn, H.; Hammons, L.; Hao, Y.; He, P.; Horn, T.; Horowitz, W. A.; Huang, M.; Hutton, A.; Jager, B.; Jackson, W.; Jain, A.; Johnson, E. C.; Kang, Z. -B.; Kaptari, L. P.; Kayran, D.; Kewisch, J.; Koike, Y.; Kondratenko, A.; Kopeliovich, B. Z.; Kovchegov, Y. V.; Krafft, G.; Kroll, P.; Kumano, S.; Kumericki, K.; Lappi, T.; Lautenschlager, T.; Li, R.; Liang, Z. -T.; Litvinenko, V. N.; Liuti, S.; Luo, Y.; Muller, D.; Mahler, G.; Majumder, A.; Manikonda, S.; Marhauser, F.; McIntyre, G.; Meskauskas, M.; Meng, W.; Metz, A.; Mezzetti, C. B.; Miller, G. A.; Minty, M.; Moch, S. -O.; Morozov, V.; Mosel, U.; Motyka, L.; Moutarde, H.; Mulders, P. J.; Musch, B.; Nadel-Turonski, P.; Nadolsky, P.; Olness, F.; Ostrumov, P. N.; Parker, B.; Pasquini, B.; Passek-Kumericki, K.; Pikin, A.; Pilat, F.; Pire, B.; Pirner, H.; Pisano, C.; Pozdeyev, E.; Prokudin, A.; Ptitsyn, V.; Qian, X.; Qiu, J. -W.; Radici, M.; Radyushkin, A.; Rao, T.; Rimmer, R.; Ringer, F.; Riordan, S.; Rogers, T.; Rojo, J.; Roser, T.; Sandapen, R.; Sassot, R.; Satogata, T.; Sayed, H.; Schafer, A.; Schnell, G.; Schweitzer, P.; Sheehy, B.; Skaritka, J.; Soyez, G.; Spata, M.; Spiesberger, H.; Stasto, A. M.; Stefanis, N. G.; Strikman, M.; Sullivan, M.; Szymanowski, L.; Tanaka, K.; Taneja, S.; Tepikian, S.; Terzic, B.; Than, Y.; Toll, T.; Trbojevic, D.; Tsentalovich, E.; Tsoupas, N.; Tuchin, K.; Tuozzolo, J.; Ullrich, T.; Vossen, A.; Wallon, S.; Wang, G.; Wang, H.; Wang, X. -N.; Webb, S.; Weiss, C.; Wu, Q.; Xiao, B. -W.; Xu, W.; Yunn, B.; Zelenski, A.; Zhang, Y.; Zhou, J.; Zurita, P.
2011-01-01
This report is based on a ten-week program on "Gluons and the quark sea at high-energies", which took place at the Institute for Nuclear Theory in Seattle in Fall 2010. The principal aim of the program was to develop and sharpen the science case for an Electron-Ion Collider (EIC), a facility that wi
TMD PDFs. A Monte Carlo implementation for the sea quark distribution
Energy Technology Data Exchange (ETDEWEB)
Hautmann, F. [Oxford Univ. (United Kingdom). Dept. of Theoretical Physics; Hentschinski, M. [Univ. Autonoma de Madrid (Spain). Dept. Fisica Teorica UAM/CSIC; Jung, H. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); European Organization for Nuclear Research (CERN), Geneva (Switzerland)
2012-05-15
This article gives an introduction to transverse momentum dependent (TMD) parton distribution functions and their use in shower Monte Carlo event generators for high-energy hadron collisions, and describes recent progress in the treatment of sea quark effects within a TMD parton-shower framework.
TMD PDFs: a Monte Carlo implementation for the sea quark distribution
Hautmann, F; Jung, H
2012-01-01
This article gives an introduction to transverse momentum dependent (TMD) parton distribution functions and their use in shower Monte Carlo event generators for high-energy hadron collisions, and describes recent progress in the treatment of sea quark effects within a TMD parton-shower framework.
Energy Technology Data Exchange (ETDEWEB)
Barik, N.; Das, M. (Utkal Univ., Bhubaneswar (India). Dept. of Physics)
1983-01-13
Several properties of octet baryons such as (i) the magnetic moment, (ii) (Gsub(A)/Gsub(v))sub(n) for neutron ..beta..-decay and (iii) the charge radius of the proton have been calculated in a simple independent-quark model under the assumption that the individual constituent quarks are confined, in first approximation, by a relativistic power-law potential Vsub(q)(r)=(1+..beta..) (asup(..nu..+1)rsup(..nu..)+V/sub 0/) with a, ..nu..>0. In view of the simplicity of the model, the results obtained are quite encouraging.
Particle creation phenomenology, Dirac sea and the induced Weyl and Einstein-dilaton gravity
Berezin, V. A.; Dokuchaev, V. I.; Eroshenko, Yu. N.
2017-01-01
We constructed the conformally invariant model for scalar particle creation induced by strong gravitational fields. Starting from the "usual" hydrodynamical description of the particle motion written in the Eulerian coordinates we substituted the particle number conservation law (which enters the formalism) by "the particle creation law", proportional to the square of the Weyl tensor (following the famous result by Ya.B. Zel'dovich and A.A. Starobinsky). Then, demanding the conformal invariance of the whole dynamical system, we have got both the (Weyl)-conformal gravity and the Einstein-Hilbert gravity action integral with dilaton field. Thus, we obtained something like the induced gravity suggested first by A.D. Sakharov. It is shown that the resulting system is self-consistent. We considered also the vacuum equations. It is shown that, beside the "empty vacuum", there may exist the "dynamical vacuum", which is nothing more but the Dirac sea. The latter is described by the unexpectedly elegant equation which includes both the Bach and Einstein tensors and the cosmological terms.
Energy Technology Data Exchange (ETDEWEB)
The Spin Muon Collaboration
1996-01-01
Semi-inclusive spin asymmetries for positively and negatively charged hadrons measured in deep inelastic scattering of polarised muons on polarised protons and deuterons are presented. The x-dependent spin distributions for up and down valence quarks and for non-strange sea quarks are determined. (author). Submitted to Physics Letters, B (NL); 18 refs.
Probing Sea Quarks and Gluons: The Electron-Ion Collider Project
Directory of Open Access Journals (Sweden)
Horn Tanja
2014-03-01
Full Text Available The 21st century holds great promise for reaching a new era for unlocking the mysteries of the structure of the atomic nucleus and the nucleons inside it governed by the theory of strong interactions (QCD. In particular, much remains to be learned about the dynamical basis of the structure of hadrons and nuclei in terms of the fundamental quarks and gluons. One of the main goals of existing and nearly completed facilities is to map out the spin flavor structure of the nucleons in the valence region. A future Electron-Ion Collider (EIC would be the world’s first polarized electron-proton collider, and the world’s first e-A collider, and would seek the QCD foundation of nucleons and nuclei in terms of the sea quarks and gluons, matching to these valence quark studies. The EIC will provide a versatile range of kinematics and beam polarization, as well as beam species, to allow for mapping the spin and spatial structure of the quark sea and gluons, to discover the collective effects of gluons in atomic nuclei, and to understand the emergence of hadronic matter from color charge.
Overlap valence quarks on a twisted mass sea. A case study for mixed action lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Cichy, Krzysztof [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Poznan Univ. (Poland). Faculty of Physics; Drach, Vincent; Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Garcia-Ramos, Elena [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Humboldt-Universitaet, Berlin (Germany); Herdoiza, Gregorio [UAM/CSIC Univ. Autonoma de Madrid (Spain). Dept. de Fisica Teorica; UAM/CSIC Univ. Autonoma de Madrid (Spain). Inst. de Fisica Teorica; Collaboration: European Twisted Mass Collaboration
2012-11-15
We discuss a Lattice QCD mixed action investigation employing Wilson maximally twisted mass sea and overlap valence fermions. Using four values of the lattice spacing, we demonstrate that the overlap Dirac operator assumes a point-like locality in the continuum limit. We also show that by adopting suitable matching conditions for the sea and valence theories a consistent continuum limit for the pion decay constant and light baryon masses can be obtained. Finally, we confront results for sea-valence mixed meson masses and the valence scalar correlator with corresponding expressions of chiral perturbation theory. This allows us to extract low energy constants of mixed action chiral perturbation which characterize the strength of unitarity violations in our mixed action setup.
Airapetian, A; Akopov, Z; Amarian, M; Ammosov, V V; Andrus, A; Aschenauer, E C; Augustyniak, W; Avakian, R; Avetisian, A; Avetissian, E; Bailey, P; Baturin, V; Baumgarten, C; Beckmann, M; Belostotskii, S; Bernreuther, S; Bianchi, N; Blok, H P; Böttcher, Helmut B; Borisov, A; Bouwhuis, M; Brack, J; Brüll, A; Bryzgalov, V V; Capitani, G P; Chiang, H C; Ciullo, G; Contalbrigo, M; Dalpiaz, P F; De Leo, R; De Nardo, L; De Sanctis, E; Devitsin, E G; Di Nezza, P; Düren, M; Ehrenfried, M; Elalaoui-Moulay, A; Elbakian, G M; Ellinghaus, F; Elschenbroich, U; Ely, J; Fabbri, R; Fantoni, A; Feshchenko, A; Felawka, L; Fox, B; Franz, J; Frullani, S; Gärber, Y; Gapienko, G; Gapienko, V; Garibaldi, F; Garrow, K; Garutti, E; Gaskell, D; Gavrilov, G E; Karibian, V; Graw, G; Grebenyuk, O; Greeniaus, L G; Hafidi, K; Hartig, M; Hasch, D; Heesbeen, D; Henoch, M; Hertenberger, R; Hesselink, W H A; Hillenbrand, A; Hoek, M; Holler, Y; Hommez, B; Iarygin, G; Ivanilov, A; Izotov, A; Jackson, H E; Jgoun, A; Kaiser, R; Kinney, E; Kiselev, A; Königsmann, K C; Kopytin, M; Korotkov, V A; Kozlov, V; Krauss, B; Krivokhizhin, V G; Lagamba, L; Lapikas, L; Laziev, A; Lenisa, P; Liebing, P; Lindemann, T; Lipka, K; Lorenzon, W; Lü, J; Maiheu, B; Makins, N C R; Marianski, B; Marukyan, H O; Masoli, F; Mexner, V; Meyners, N; Miklukho, O; Miller, C A; Miyachi, Y; Muccifora, V; Nagaitsev, A; Nappi, E; Naryshkin, Yu; Nass, A; Negodaev, M A; Nowak, Wolf-Dieter; Oganessyan, K; Ohsuga, H; Orlandi, G; Pickert, N; Potashov, S Yu; Potterveld, D H; Raithel, M; Reggiani, D; Reimer, P E; Reischl, A; Reolon, A R; Riedl, C; Rith, K; Rosner, G; Rostomyan, A; Rubacek, L; Ryckbosch, D; Salomatin, Yu I; Sanjiev, I; Savin, I; Scarlett, C; Schäfer, A; Schill, C; Schnell, G; Schüler, K P; Schwind, A; Seele, J; Seidl, R; Seitz, B; Shanidze, R G; Shearer, C; Shibata, T A; Shutov, V B; Simani, M C; Sinram, K; Stancari, M D; Statera, M; Steffens, E; Steijger, J J M; Stewart, J; Stösslein, U; Tait, P; Tanaka, H; Taroian, S P; Tchuiko, B; Terkulov, A R; Tkabladze, A V; Trzcinski, A; Tytgat, M; Vandenbroucke, A; Van der Nat, P B; van der Steenhoven, G; Vetterli, Martin C; Vikhrov, V; Vincter, M G; Visser, J; Vogel, C; Vogt, M; Volmer, J; Weiskopf, C; Wendland, J; Wilbert, J; Ybeles-Smit, G V; Yen, S; Zihlmann, B; Zohrabyan, H G; Zupranski, P
2004-01-01
Double-spin asymmetries of semi-inclusive cross sections for the production of identified pions and kaons have been measured in deep-inelastic scattering of polarized positrons on a polarized deuterium target. Five helicity distributions including those for three sea quark flavors were extracted from these data together with re-analyzed previous data for identified pions from a hydrogen target. These distributions are consistent with zero for all three sea flavors. There is no evidence of either the negative polarization of the strange sea that appears in analyses of only inclusive data, or of a recently predicted flavor asymmetry in the polarization of the light quark sea.
Determination of Strange Sea Quark Distributions from Fixed-target and Collider Data
Alekhin, S; Caminadac, L; Lipka, K; Lohwasser, K; Moch, S; Petti, R; Placakyte, R
2014-01-01
We present an improved determination of the strange sea distribution in the nucleon with constraints coming from the recent charm production data in neutrino-nucleon deep-inelastic scattering by the NOMAD and CHORUS experiments and from charged current inclusive deep-inelastic scattering at HERA. We demonstrate that the results are consistent with the data from the ATLAS and the CMS experiments on the associated production of $W^\\pm$-bosons with $c$-quarks. We also discuss issues related to the recent strange sea determination by the ATLAS experiment using LHC collider data.
Determination of strange sea quark distributions from fixed-target and collider data
Energy Technology Data Exchange (ETDEWEB)
Alekhin, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Institut Fiziki Vysokikh Ehnergij, Protvino (Russian Federation); Bluemlein, J.; Lohwasser, K. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Caminada, L. [Zuerich Univ. (Switzerland). Physik Inst.; Lipka, K.; Placakyt e, R. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Moch, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Petti, R. [South Carolina Univ., Columbia, SC (United States). Dept. of Physics and Astronomy
2014-04-15
We present an improved determination of the strange sea distribution in the nucleon with constraints coming from the recent charm production data in neutrino-nucleon deep-inelastic scattering by the NOMAD and CHORUS experiments and from charged current inclusive deep-inelastic scattering at HERA. We demonstrate that the results are consistent with the data from the ATLAS and the CMS experiments on the associated production of W{sup ±}-bosons with c-quarks. We also discuss issues related to the recent strange sea determination by the ATLAS experiment using LHC collider data.
The Body Center Cubic Quark Lattice Model
Lin Xu, Jiao
2004-01-01
The Standard Model while successful in many ways is incomplete; many questions remain. The origin of quark masses and hadronization of quarks are awaiting an answer. From the Dirac sea concept, we infer that two kinds of elementary quarks (u(0) and d(0)) constitute a body center cubic (BCC) quark lattice with a lattice constant a < $10^{-18}$m in the vacuum. Using energy band theory and the BCC quark lattice, we can deduce the rest masses and the intrinsic quantum numbers (I, S, C, b and Q) of quarks. With the quark spectrum, we deduce a baryon spectrum. The theoretical spectrum is in agreement well with the experimental results. Not only will this paper provide a physical basis for the Quark Model, but also it will open a door to study the more fundamental nature at distance scales <$10^{-18}$m. This paper predicts some new quarks $u_{c}$(6490) and d$_{b}$(9950), and new baryons $\\Lambda_{c}^{+}$(6500), $\\Lambda_{b}^{0}$(9960).
Measurement of Quark Energy Loss in Cold Nuclear Matter at Fermilab E906/SeaQuest
Energy Technology Data Exchange (ETDEWEB)
Lin, Po-Ju [Colorado U.
2017-01-01
Parton energy loss is a process within QCD that draws considerable interest. The measurement of parton energy loss can provide valuable information for other hard-scattering processes in nuclei, and also serves as an important tool for exploring the properties of the quark-gluon plasma (QGP). Quantifying the energy loss in cold nuclear matter will help to set a baseline relative to energy loss in the QGP. With the Drell-Yan process, the energy loss of incoming quarks in cold nuclear matter can be ideally investigated since the final state interaction is expected to be minimal. E906/SeaQuest is a fixed-target experiment using the 120 GeV proton beam from the Fermilab Main Injector and has been collecting data from p+p, p+d, p+C, p+Fe, and p+W collisions. Within the E906 kinematic coverage of Drell-Yan production via the dimuon channel, the quark energy loss can be measured in a regime where other nuclear effects are expected to be small. In this thesis, the study of quark ener gy loss from different cold nuclear targets is presented.
First attempt to overcome the disaster of Dirac sea in imaginary time step method
Institute of Scientific and Technical Information of China (English)
ZHANG Ying; LIANG Hao-Zhao; MENG Jie
2009-01-01
Efforts have been made to solve the Dirac equation with axially deformed scalar and vector Woods-Saxon potentials in the coordinate space with the imaginary time step method. The results of the single-particle energies thus obtained are consistent with those calculated with the basis expansion method, which demonstrates the feasibility of the imaginary time step method for the relativistic static problems.
Nucleon form factors in an independent-quark model based on Dirac equation with power-law potential
Energy Technology Data Exchange (ETDEWEB)
Barik, N.; Das, M.
1986-01-01
The nucleon electromagnetic form factors G/sub E//sup p/(qS) and G/sub M//sup p/(qS) and the axial-vector form factor G/sub A/(qS) are investigated in a simple model of relativistic quarks confined by a vector-scalar mixed potential U/sub q/(r) = (1+el)(a/sup nu+1/r/sup / +V0) without taking into account the center-of-mass correction and the pion-cloud effects. The respective rms radii associated with G/sub E//sup p/(qS) and G/sub A/(qS) come out as
Airapetian, A; Akopov, N; Akopov, Z; Amarian, M; Ammosov, V V; Andrus, A; Aschenauer, E C; Augustyniak, W; Avakian, R; Avetissian, A; Avetissian, E; Bailey, P; Baturin, V; Baumgarten, C; Beckmann, M; Belostotski, S; Bernreuther, S; Bianchi, N; Blok, H P; Böttcher, H; Borissov, A; Bouwhuis, M; Brack, J; Brüll, A; Bryzgalov, V; Capitani, G P; Chiang, H C; Ciullo, G; Contalbrigo, M; Dalpiaz, P F; De Leo, R; De Nardo, L; De Sanctis, E; Devitsin, E; Di Nezza, P; Düren, M; Ehrenfried, M; Elalaoui-Moulay, A; Elbakian, G; Ellinghaus, F; Elschenbroich, U; Ely, J; Fabbri, R; Fantoni, A; Fechtchenko, A; Felawka, L; Fox, B; Franz, J; Frullani, S; Gärber, Y; Gapienko, G; Gapienko, V; Garibaldi, F; Garrow, K; Garutti, E; Gaskell, D; Gavrilov, G; Gharibyan, V; Graw, G; Grebeniouk, O; Greeniaus, L G; Hafidi, K; Hartig, M; Hasch, D; Heesbeen, D; Henoch, M; Hertenberger, R; Hesselink, W H A; Hillenbrand, A; Hoek, M; Holler, Y; Hommez, B; Iarygin, G; Ivanilov, A; Izotov, A; Jackson, H E; Jgoun, A; Kaiser, R; Kinney, E; Kisselev, A; Königsmann, K; Kopytin, M; Korotkov, V; Kozlov, V; Krauss, B; Krivokhijine, V G; Lagamba, L; Lapikás, L; Laziev, A; Lenisa, P; Liebing, P; Lindemann, T; Lipka, K; Lorenzon, W; Lu, J; Maiheu, B; Makins, N C R; Marianski, B; Marukyan, H; Masoli, F; Mexner, V; Meyners, N; Mikloukho, O; Miller, C A; Miyachi, Y; Muccifora, V; Nagaitsev, A; Nappi, E; Naryshkin, Y; Nass, A; Negodaev, M; Nowak, W-D; Oganessyan, K; Ohsuga, H; Orlandi, G; Pickert, N; Potashov, S; Potterveld, D H; Raithel, M; Reggiani, D; Reimer, P E; Reischl, A; Reolon, A R; Riedl, C; Rith, K; Rosner, G; Rostomyan, A; Rubacek, L; Ryckbosch, D; Salomatin, Y; Sanjiev, I; Savin, I; Scarlett, C; Schäfer, A; Schill, C; Schnell, G; Schüler, K P; Schwind, A; Seele, J; Seidl, R; Seitz, B; Shanidze, R; Shearer, C; Shibata, T-A; Shutov, V; Simani, M C; Sinram, K; Stancari, M; Statera, M; Steffens, E; Steijger, J J M; Stewart, J; Stösslein, U; Tait, P; Tanaka, H; Taroian, S; Tchuiko, B; Terkulov, A; Tkabladze, A; Trzcinski, A; Tytgat, M; Vandenbroucke, A; Van Der Nat, P; Van Der Steenhoven, G; Vetterli, M C; Vikhrov, V; Vincter, M G; Visser, J; Vogel, C; Vogt, M; Volmer, J; Weiskopf, C; Wendland, J; Wilbert, J; Ybeles Smit, G; Yen, S; Zihlmann, B; Zohrabian, H; Zupranski, P
2004-01-09
Double-spin asymmetries of semiinclusive cross sections for the production of identified pions and kaons have been measured in deep inelastic scattering of polarized positrons on a polarized deuterium target. Five helicity distributions including those for three sea quark flavors were extracted from these data together with reanalyzed previous data for identified pions from a hydrogen target. These distributions are consistent with zero for all three sea flavors. A recently predicted flavor asymmetry in the polarization of the light quark sea appears to be disfavored by the data.
Continuum limit of overlap valence quarks on a twisted mass sea
Energy Technology Data Exchange (ETDEWEB)
Cichy, Krzysztof [Adam Mickiewicz Univ., Poznan (Poland). Faculty of Physics; Herdoiza, Gregorio [DESY, Zeuthen (Germany). John von Neumann-Institut fuer Computing NIC; Univ. Autonoma de Madrid (Spain). Dept. de Fisica Teorica; Jansen, Karl [DESY, Zeuthen (Germany). John von Neumann-Institut fuer Computing NIC
2010-12-15
We study a lattice QCD mixed action with overlap valence quarks on two flavours of Wilson maximally twisted mass sea quarks. Employing three different matching conditions to relate both actions to each other, we investigate the continuum limit by using three values of the lattice spacing ranging from a{approx}0.05 fm to 0.08 fm. A particular emphasis is put on the effect on physical observables of the topological zero modes appearing in the valence overlap operator. We estimate the region of parameter space where the contribution from these zero modes is sufficiently small such that their effects can be safely controlled and a restoration of unitarity of the mixed action in the continuum limit is reached. (orig.)
Continuum Limit of Overlap Valence Quarks on a Twisted Mass Sea
Cichy, Krzysztof; Jansen, Karl
2010-01-01
We study a lattice QCD mixed action with overlap valence quarks on two flavours of Wilson maximally twisted mass sea quarks. Employing three different matching conditions to relate both actions to each other, we investigate the continuum limit by using three values of the lattice spacing ranging from 0.05 fm to 0.08 fm. A particular emphasis is put on the effect on physical observables of the topological zero modes appearing in the valence overlap operator. We estimate the region of parameter space where the contribution from these zero modes is sufficiently small such that their effects can be safely controlled and a restoration of unitarity of the mixed action in the continuum limit is reached.
Forward Z-boson production and the unintegrated sea quark density
Hautmann, F; Jung, H
2012-01-01
Drell-Yan production in the forward region at the Large Hadron Collider is sensitive to multiple radiation of QCD partons not collinearly ordered, emitted over large rapidity intervals. We propose a method to take account of these radiative contributions via a factorization formula which depends on the unintegrated, or transverse momentum dependent, splitting function associated with the evolution of the initial-state sea quark distribution. We analyze this formula numerically, and point out kinematic effects from the initial-state transverse momentum on the vector boson spectrum.
Energy Technology Data Exchange (ETDEWEB)
Abel, Steven [Durham Univ. (United Kingdom). Inst. for Particle Physics Phenomenology; CERN, Geneva (Switzerland); Goodsell, Mark [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2011-02-15
A simple and natural model is presented that gives Dirac gauginos. The configuration is related to ''deconstructed gaugino mediation''. A high energy completion is provided based on existing ISS-like models of deconstructed gaugino mediation. This provides a complete picture of Dirac gauginos that includes the necessary extra adjoint fermions (generated as magnetic quarks of the ISS theory) and supersymmetry breaking (via the ISS mechanism). Moreover the screening of the scalar masses means that they can similar to or less than the gaugino masses, even though the supersymmetry breaking is driven by F-terms. (orig.)
Gluons and the Quark Sea at High Energies: Distributions, Polarization, Tomography
Energy Technology Data Exchange (ETDEWEB)
Boer, Daniel; /Groningen U.; Diehl, Markus; /DESY; Milner, Richard; /MIT; Venugopalan, Raju; /Brookhaven; Vogelsang, Werner; /Tubingen U.; Kaplan, David; /Washington U., Seattle; Montgomery, Hugh; /Jefferson Lab; Vigdor, Steven; /Brookhaven; Accardi, A.; /Jefferson Lab; Aschenauer, E.C.; /Brookhaven; Burkardt, M.; /New Mexico State U.; Ent, R.; /Jefferson Lab; Guzey, V.; /Jefferson Lab; Hasch, D.; /Frascati; Kumar, K.; /Massachusetts U., Amherst; Lamont, M.A.C.; /Brookhaven; Li, Ying-chuan; /Brookhaven; Marciano, W.; /Brookhaven; Marquet, C.; /CERN; Sabatie, F.; /IRFU, SPhN, Saclay; Stratmann, M.; /Brookhaven /LBL, Berkeley /Buenos Aires U. /Antwerp U. /Pelotas U. /Moncton U. /Santa Maria U., Valparaiso /CCTVal, Valparaiso /Hefei, CUST /Shandong U., Weihai /Boskovic Inst., Zagreb /Zagreb U., Phys. Dept. /Jyvaskyla U. /Orsay, LPT /Paris U., VI-VII /Ecole Polytechnique, CPHT /IRFU, SPhN, Saclay /Saclay, SPhT /Ruhr U., Bochum /Giessen U. /DESY /Hamburg U., Inst. Theor. Phys. II /Heidelberg U. /Mainz U., Inst. Kernphys. /Mainz U., Inst. Phys. /Regensburg U. /Tubingen U. /Wuppertal U. /DESY /Cagliari U. /INFN, Cagliari /Frascati /Milan U. /INFN, Milan /INFN, Pavia /Pavia U. /INFN, Perugia /Perugia U.; /more authors..
2012-06-07
This report on the science case for an Electron-Ion Collider (EIC) is the result of a ten-week program at the Institute for Nuclear Theory (INT) in Seattle (from September 13-November 19, 2010), motivated by the need to develop a strong case for the continued study of the QCD description of hadron structure in the coming decades. Hadron structure in the valence quark region will be studied extensively with the Jefferson Lab 12 GeV science program, the subject of an INT program the previous year. The focus of the INT program was on understanding the role of gluons and sea quarks, the important dynamical degrees of freedom describing hadron structure at high energies. Experimentally, the most direct and precise way to access the dynamical structure of hadrons and nuclei at high energies is with a high luminosity lepton probe in collider mode. An EIC with optimized detectors offers enormous potential as the next generation accelerator to address many of the most important, open questions about the fundamental structure of matter. The goal of the INT program, as captured in the writeups in this report, was to articulate these questions and to identify golden experiments that have the greatest potential to provide definitive answers to these questions. At resolution scales where quarks and gluons become manifest as degrees of freedom, the structure of the nucleon and of nuclei is intimately connected with unique features of QCD dynamics, such as confinement and the self-coupling of gluons. Information on hadron sub-structure in DIS is obtained in the form of 'snapshots' by the 'lepton microscope' of the dynamical many-body hadron system, over different momentum resolutions and energy scales. These femtoscopic snapshots, at the simplest level, provide distribution functions which are extracted over the largest accessible kinematic range to assemble fundamental dynamical insight into hadron and nuclear sub-structure. For the proton, the EIC would be
Sequential deconfinement of quark flavors in neutron stars
Blaschke, D; Klahn, T; Berdermann, J
2008-01-01
We suggest a scenario where the three light quark flavors are sequentially deconfined under increasing pressure in cold asymmetric nuclear matter as found, e.g., in neutron stars. The basis for our analysis is a chiral quark matter model of Nambu--Jona-Lasinio (NJL) type with diquark pairing in the spin-1 single flavor (CSL), spin-0 two flavor (2SC) and three flavor (CFL) channels. We find that nucleon dissociation sets in at about the saturation density, n_0, when the down-quark Fermi sea is populated (d-quark dripline) due to the flavor asymmetry induced by beta-equilibrium and charge neutrality. At about 3n_0 u-quarks appear and a two-flavor color superconducting (2SC) phase is formed. The s-quark Fermi sea is populated only at still higher baryon density, when the quark chemical potential is of the order of the dynamically generated strange quark mass. We construct two different hybrid equations of state (EoS) using the Dirac-Brueckner Hartree-Fock (DBHF) approach and the EoS by Shen et al. in the nuclear...
Stochastic calculation of the QCD Dirac operator spectrum with Mobius domain-wall fermion
Cossu, G; Hashimoto, S; Kaneko, T; Noaki, J
2016-01-01
We calculate the spectral function of the QCD Dirac operator using the four-dimensional effective operator constructed from the Mobius domain-wall implementation. We utilize the eigenvalue filtering technique combined with the stochastic estimate of the mode number. The spectrum in the entire eigenvalue range is obtained with a single set of measurements. Results on 2+1-flavor ensembles with Mobius domain-wall sea quarks at lattice spacing ~ 0.08 fm are shown.
Strangeness content and structure function of the nucleon in a statistical quark model
Trevisan, L A; Tomio, L
1999-01-01
The strangeness content of the nucleon is determined from a statistical model using confined quark levels, and is shown to have a good agreement with the corresponding values extracted from experimental data. The quark levels are generated in a Dirac equation that uses a linear confining potential (scalar plus vector). With the requirement that the result for the Gottfried sum rule violation, given by the new muon collaboration (NMC), is well reproduced, we also obtain the difference between the structure functions of the proton and neutron, and the corresponding sea quark contributions. (27 refs).
Sochichiu, Corneliu
2011-01-01
We study the emergence of Dirac fermionic field in the low energy description of non-relativistic dynamical network models. The Dirac fermionic field appears as the effective field describing the excitations above point-like Fermi levels. Together with the Dirac fermionic field an effective space-time metric is also emerging. We analyze the conditions for such Fermi points to appear in general, paying special attention to the case of two and three spacial dimensions.
The role of strange sea quarks in chiral extrapolations on the lattice
Descotes-Genon, S
2004-01-01
Since the strange quark has a light mass of order Lambda_QCD, fluctuations of sea s-s bar pairs may play a special role in the low-energy dynamics of QCD by inducing significantly different patterns of chiral symmetry breaking in the chiral limits N_f=2 (m_u=m_d=0, m_s physical) and N_f=3 (m_u=m_d=m_s=0). This effect of vacuum fluctuations of s-s bar pairs is related to the violation of the Zweig rule in the scalar sector, described through the two O(p^4) low-energy constants L_4 and L_6 of the three-flavour strong chiral lagrangian. In the case of significant vacuum fluctuations, three-flavour chiral expansions might exhibit a numerical competition between leading- and next-to-leading-order terms according to the chiral counting, and chiral extrapolations should be handled with a special care. We investigate the impact of the fluctuations of s-s bar pairs on chiral extrapolations in the case of lattice simulations with three dynamical flavours in the isospin limit. Information on the size of the vacuum fluct...
Gluons and the quark sea at high energies: distributions, polarization, tomography
Boer, D; Milner, Richard; Venugopalan, Raju; Vogelsang, Werner; Kaplan, David; Montgomery, Hugh; Vigdor, Steven; Accardi, A.; Aschenauer, E.C.; Burkardt, M.; Ent, R.; Guzey, V.; Hasch, D.; Kumar, K.; Lamont, M.A.C.; Li, Ying-chuan; Marciano, W.; Marquet, C.; Sabatie, F.; Stratmann, M.; Yuan, F.; Sassot, R.; Zurita, P.; Cherednikov, I.O.; Goncalves, V.P.; Sandapen, R.; Kopeliovich, B.Z.; Gao, J.-H.; Liang, Z.-T.; Passek-Kumericki, K.; Kumericki, K.; Lappi, T.; Wallon, S.; Pire, B.; Geraud, R.; Moutarde, H.; Gelis, F.; Soyez, G.; Meskauskas, M.; Mueller, Dieter; Stefanis, N.G.; Gallmeister, K.; Mosel, U.; Diehl, M.; Bartels, J.; Pirner, H.J.; Hagler, P.; Jager, B.; Spiesberger, H.; Lautenschlager, T.; Schafer, A.; Ringer, F.; Vogelsang, W.; Kroll, P.; Alekhin, S.; Blumlein, J; Moch, S.-O.; Pisano, C.; Rojo, J.; Bacchetta, A.; Pasquini, B.; Radici, M.; Ciofi degli Atti, C.; Mezzetti, C.B.; Kaptari, L.P.; Anselmino, M.; Tanaka, K.; Koike, Y.; Kumano, S.; Motyka, L.; Golec-Biernat, K.; Stasto, A.M.; Golec-Biernat, K.; Szymanowski, L.; Cherednikov, I.O.; Kaptari, L.P.; Radyushkin, A.; Alekhin, S.; Kondratenko, A.; Horowitz, W.A.; Schnell, G.; Chevtsov, P.; Mulders, P.J.; Rogers, T.C.; Boer, D.; Forshaw, J.R.; Cooper-Sarkar, A.; Chirilli, G.A.; Muller, D.; Wang, X.-N.; Yuan, F.; Qian, X.; Brodsky, S.J.; Schweitzer, P.; Horn, T.; Tuchin, K.; Dupre, R.; Erdelyi, B.; Manikonda, S.; Ostrumov, P.N.; Abeyratne, S.; Erdelyi, B.; Vossen, A.; Riordan, S.; Tsentalovich, E.; Goldstein, G.R.; Pozdeyev, E.; Huang, M.; Aidala, C.; Dumitru, A.; Dominguez, F.; Ben-Zvi, I.; Deshpande, A.; Faroughy, C.; Hammons, L.; Hao, Y.; Johnson, E.C.; Litvinenko, V.N.; Taneja, S.; Tsoupas, N.; Webb, S.; Beebe-Wang, J.; Belomestnykh, S.; Ben-Zvi, I.; Blaskiewicz, M.M.; Calaga, R.; Chang, X.; Fedotov, A.; Gassner, D.; Hahn, H.; Hammons, L.; Hao, Y.; He, P.; Jackson, W.; Jain, A.; Johnson, E.C.; Kayran, D.; Kewisch, J.; Litvinenko, V.N.; Luo, Y.; Mahler, G.; McIntyre, G.; Meng, W.; Minty, M.; Parker, B.; Pikin, A.; Ptitsyn, V.; Rao, T.; Roser, T.; Sheehy, B.; Skaritka, J.; Tepikian, S.; Than, Y.; Trbojevic, D.; Tsoupas, N.; Tuozzolo, J.; Wang, G.; Webb, S.; Wu, Q.; Xu, W.; Zelenski, A.; Beuf, G.; Burton, T.; Debbe, R.; Fazio, S.; Marciano, W.J.; Qiu, J.-W.; Toll, T.; Ullrich, T.; Deshpande, A.; Dumitru, A.; Kang, Z.-B.; Stasto, A.M.; Yuan, F.; Kovchegov, Y.V.; Majumder, A; Metz, A.; Zhou, J.; Gamberg, L.; Stasto, A.M.; Strikman, M.; Xiao, B.-W.; Guzzi, M.; Nadolsky, P.; Olness, F.; BC, H.; Liuti, S.; Ahmed, S.; Bogacz, A.; Derbenev, Ya.; Hutton, A.; Krafft, G.; Li, R.; Marhauser, F.; Morozov, V.; Pilat, F.; Rimmer, R.; Satogata, T.; Sullivan, M.; Spata, M.; Terzic, B.; Wang, H.; Yunn, B.; Zhang, Y.; Avakian, H.; Musch, B.; Nadel-Turonski, P.; Prokudin, A.; Radyushkin, A.; Weiss, C.; Krafft, G.; Radyushkin, A.; Sayed, H.; Gilfoyle, G.P.; Cloet, I.C.; Miller, G.; Gonderinger, M.
2011-01-01
This report is based on a ten-week program on "Gluons and the quark sea at high-energies", which took place at the Institute for Nuclear Theory in Seattle in Fall 2010. The principal aim of the program was to develop and sharpen the science case for an Electron-Ion Collider (EIC), a facility that will be able to collide electrons and positrons with polarized protons and with light to heavy nuclei at high energies, offering unprecedented possibilities for in-depth studies of quantum chromodynamics. This report is organized around four major themes: i) the spin and flavor structure of the proton, ii) three-dimensional structure of nucleons and nuclei in momentum and configuration space, iii) QCD matter in nuclei, and iv) Electroweak physics and the search for physics beyond the Standard Model. Beginning with an executive summary, the report contains tables of key measurements, chapter overviews for each of the major scientific themes, and detailed individual contributions on various aspects of the scientific op...
Gluons and the quark sea at high energies: distributions, polarization, tomography
Energy Technology Data Exchange (ETDEWEB)
Boer, D.; Venugopalan, R.; Diehl, M.; Milner, R.; Vogelsang, W.; et al.
2011-09-30
This report is based on a ten-week program on Gluons and the quark sea at high-energies, which took place at the Institute for Nuclear Theory (INT) in Seattle in Fall 2010. The principal aim of the program was to develop and sharpen the science case for an Electron-Ion Collider (EIC), a facility that will be able to collide electrons and positrons with polarized protons and with light to heavy nuclei at high energies, offering unprecedented possibilities for in-depth studies of quantum chromodynamics (QCD). This report is organized around the following four major themes: (i) the spin and flavor structure of the proton, (ii) three dimensional structure of nucleons and nuclei in momentum and configuration space, (iii) QCD matter in nuclei, and (iv) Electroweak physics and the search for physics beyond the Standard Model. Beginning with an executive summary, the report contains tables of key measurements, chapter overviews for each of the major scientific themes, and detailed individual contributions on various aspects of the scientific opportunities presented by an EIC.
Probing the Quark Sea and Gluons: the Electron-Ion Collider Projects
Energy Technology Data Exchange (ETDEWEB)
Rolf Ent
2012-04-01
EIC is the generic name for the nuclear science-driven Electron-Ion Collider presently considered in the US. Such an EIC would be the world’s first polarized electron-proton collider, and the world’s first e-A collider. Very little remains known about the dynamical basis of the structure of hadrons and nuclei in terms of the fundamental quarks and gluons of Quantum Chromodynamics (QCD). A large community effort to sharpen a compelling nuclear science case for an EIC occurred during a ten-week program taking place at the Institute for Nuclear Theory (INT) in Seattle from September 13 to November 19, 2010. The critical capabilities of a stage-I EIC are a range in center-of-mass energies from 20 to 70 GeV and variable, full polarization of electrons and light ions (the latter both longitudinal and transverse), ion species up to A=200 or so, multiple interaction regions, and a high luminosity of about 10{sup 34} electron-nucleons per cm{sup 2} and per second. The physics program of such a stage-I EIC encompass inclusive measurements (ep/A{yields}e'+X), which require detection of the scattered lepon and/or the full scattered hadronic debris with high precision, semi-inclusive processes (ep/A{yields}e'+h+X), which require detection in coincidence with the scattered lepton of at least one (current or target region) hadron; and exclusive processes (ep/A{yields}e'+N'/A'+{gamma}/m), which require detection of all particles in the reaction. The main science themes of an EIC are to i) map the spin and spatial structure of quarks and gluons in nucleons, ii) discover the collective effects of gluons in atomic nuclei, and (iii) understand the emergence of hadronic matter from color charge. In addition, there are opportunities at an EIC for fundamental symmetry and nucleon structure measurements using the electroweak probe. To truly make headway to image the sea quarks and gluons in nucleons and nuclei, the EIC needs high luminosity over a range of
Rivasseau, Vincent; Fuchs, Jean-Nöel
2017-01-01
This fifteenth volume of the Poincare Seminar Series, Dirac Matter, describes the surprising resurgence, as a low-energy effective theory of conducting electrons in many condensed matter systems, including graphene and topological insulators, of the famous equation originally invented by P.A.M. Dirac for relativistic quantum mechanics. In five highly pedagogical articles, as befits their origin in lectures to a broad scientific audience, this book explains why Dirac matters. Highlights include the detailed "Graphene and Relativistic Quantum Physics", written by the experimental pioneer, Philip Kim, and devoted to graphene, a form of carbon crystallized in a two-dimensional hexagonal lattice, from its discovery in 2004-2005 by the future Nobel prize winners Kostya Novoselov and Andre Geim to the so-called relativistic quantum Hall effect; the review entitled "Dirac Fermions in Condensed Matter and Beyond", written by two prominent theoreticians, Mark Goerbig and Gilles Montambaux, who consider many other mater...
A Dirac Sea for a General Non-Inertial Observer In Flat 1+1 Dimensional Spacetime
Goodsell, M D; Gull, S F; Goodsell, Mark D.; Dolby, Carl E.; Gull, Stephen F.
2002-01-01
A coordinate system is set up for a general accelerating observer and is used to determine the particle content of the Dirac vacuum for that observer. Equations are obtained for the spatial distribution and total number of particles for massless fermions as seen by this observer, generalising previous work.
Probing Flavor Asymmetry of Anti-quarks in the Proton by Drell-Yan Experiment SeaQuest
Energy Technology Data Exchange (ETDEWEB)
Miyasaka, Shou [Tokyo Inst. Tech.
2016-01-01
A new measurement on the avor asymmetry between d and u in the proton is reported in this thesis. The proton contains a substantial number of antiquarks which arise from dynamical interactions of gluons such as gluon dissociation to a quark-antiquark pair, g ! q + q, and from non-perturbative processes as described by the pion-cloud model, for example. The antiquarks in the proton undertake an important role in determining the dynamic characteristics of the internal structure of the proton, although its distribution in the proton and its origin are not fully understood. Understanding sea quarks in hadron is an important subject for QCD. The SeaQuest experiment at Fermi National Accelerator Laboratory (Fermilab) is a xed target experiment using the 120 GeV proton beam extracted from the Fermilab Main Injector. One of the goals of the experiment is to measure the avor asymmetry between d quark and u quark in the proton as a function of the target Bjorken x using the Drell-Yan process in the p-p or p-d reactions. This process takes place in hadron-hadron collisions when a quark in one hadron in the beam and an antiquark in other hadron in the target annihilate into a virtual photon that decays into a lepton pair. The avor asymmetry between d and u quarks was found by deep-inelastic scattering experiment NMC at CERN. The E866/NuSea experiment at Fermilab obtained the avor asymmetry in the proton for 0:015 < x < 0:35 using the 800 GeV proton beam extracted from the Fermilab Tevatron. The result indicates the dominance of d; it is 70% larger than u at lower x. The SeaQuest experiment was planned to do a new precise measurement at higher x region. The lower energy beam (120 GeV) increases the Drell-Yan cross section and suppresses the background primarily arising from J/ decays. Therefore, SeaQuest will obtain more statistics in a shorter time than the E866 experiment. After detector construction, detector commissioning and accelerator upgrade, physics data taking started
Pathways to Naturally Small Dirac Neutrino Masses
Ma, Ernest
2016-01-01
If neutrinos are truly Dirac fermions, the smallness of their masses may still be natural if certain symmetries exist beyond those of the standard model of quarks and leptons. We perform a systematic study of how this may occur at tree level and in one loop. We also propose a scotogenic version of the left-right gauge model with naturally small Dirac neutrino masses in one loop.
Casajús Ramo, A
2006-01-01
DIRAC is the LHCb Workload and Data Management System. Based on a service-oriented architecture, it enables generic distributed computing with lightweight Agents and Clients for job execution and data transfers. DIRAC implements a client-server architecture exposing server methods through XML Remote Procedure Call (XML-RPC) protocol. DIRAC is mostly coded in python. DIRAC security infrastructure has been designed to be a completely generic XML-RPC transport over a SSL tunnel. This new security layer is able to handle standard X509 certificates as well as grid-proxies to authenticate both sides of the connection. Serve and client authentication relies over OpenSSL and py-Open SSL, but to be able to handle grid proxies some modifications have been added to those libraries. DIRAC security infrastructure handles authorization and authorization as well as provides extended capabilities like secure connection tunneling and file transfer. Using this new security infrastructure all LHCb users can safely make use o...
Li, Xuan
2014-01-01
The STAR experiment at RHIC is carrying out a comprehensive high-energy spin physics program to understand the internal structure and dynamics of the proton in polarized proton-proton collisions at $\\sqrt{s} = 200$ GeV and $\\sqrt{s} = 500/510$ GeV. STAR has the capability, with nearly full azimuthal coverage, to reconstruct leptons, hadrons and jets in the mid-rapidity region ($|\\eta|<1$). The results for inclusive jet longitudinal double spin asymmetries taken during the 2009 RHIC run indicate the first non-zero gluon contribution ($\\Delta g(x,Q^{2}) / g(x,Q^{2})$) to the proton spin for $0.05
Gómez, F; Afanasev, L; Benayoun, M; Brekhovskikh, V; Caragheorgheopol, G; Cechák, T; Chiba, M; Constantinescu, S; Doudarev, A; Dreossi, D; Drijard, Daniel; Ferro-Luzzi, M; Gallas, M V; Gerndt, J; Giacomich, R; Gianotti, P; Goldin, D; Gorin, A; Gortchakov, O; Guaraldo, C; Hansroul, M; Hosek, R; Iliescu, M; Jabitski, M; Kalinina, N; Karpoukhine, V; Kluson, J; Kobayshi, M; Kokkas, P; Komarov, V; Koulikov, A; Kouptsov, A; Krouglov, V; Krouglova, L; Kuroda, K I; Lanaro, A; Lapshine, B; Lednicky, R; Leruste, P; Levisandri, P; López-Aguera, A; Lucherini, V; Mäki, T; Manuilov, I; Montanet, L; Narjoux, J L; Nemenov, L; Nikitin, M; Nunez Pardo, T; Okada, K; Olchevskii, V; Pazos, A; Pentia, M; Penzo, Aldo L; Perreau, J M; Petrascu, C; Pló, M; Ponta, T; Pop, D; Riazantsev, A; Rodríguez, J M; Rodriguez Fernandez, A; Rykaline, V; Santamarina, C; Saborido, J; Schacher, J; Sidorov, A; Smolik, J; Takeutchi, F; Tarasov, A; Tauscher, L; Tobar, M J; Trusov, S; Vasquez, P; Vlachos, S; Yazkov, V; Yoshimura, Y; Zrelov, P
2001-01-01
The main objective of DIRAC experiment is the measurement of the lifetime tau of the exotic hadronic atom consisting of pi /sup +/ and pi /sup -/ mesons. The lifetime of this atom is determined by the decay mode pi /sup +/ pi /sup -/ to pi /sup 0/ pi /sup 0/ due to the strong interaction. Through the precise relationship between the lifetime and the S-wave pion-pion scattering length difference a/sub 0/-a/sub 2/ for isospin 0 and 2 (respectively), a measurement of tau with an accuracy of 10% will allow a determination of a/sub 0/-a/sub 2/at a 5% precision level. Pion-pion scattering lengths have been calculated in the framework of chiral perturbation theory with an accuracy below 5%. In this way DIRAC experiment will provide a crucial test of the chiral symmetry breaking scheme in QCD effective theories at low energies. (19 refs).
Energy Technology Data Exchange (ETDEWEB)
CREUTZ, M.
2006-01-26
It is popular to discuss low energy physics in lattice gauge theory ill terms of the small eigenvalues of the lattice Dirac operator. I play with some ensuing pitfalls in the interpretation of these eigenvalue spectra. In short, thinking about the eigenvalues of the Dirac operator in the presence of gauge fields can give some insight, for example the elegant Banks-Casher picture for chiral symmetry breaking. Nevertheless, care is necessary because the problem is highly non-linear. This manifests itself in the non-intuitive example of how adding flavors enhances rather than suppresses low eigenvalues. Issues involving zero mode suppression represent one facet of a set of connected unresolved issues. Are there non-perturbative ambiguities in quantities such as the topological susceptibility? How essential are rough gauge fields, i.e. gauge fields on which the winding number is ambiguous? How do these issues interplay with the quark masses? I hope the puzzles presented here will stimulate more thought along these lines.
Hadron spectra and Delta_{mix} from overlap quarks on a HISQ sea
Basak, S; Mathur, N; Lytle, A T; Majumdar, P; Padmanath, M
2014-01-01
We present results of our continuing study on mixed-action hadron spectra and decay constants using overlap valence quarks on MILC's 2+1+1 flavor HISQ gauge configurations. This study is carried out on three lattice spacings, with charm and strange masses tuned to their physical values, and with m_l/m_s = 1/5. We present results of an ongoing determination of the mixed-action parameter Delta_{mix}, which enters into chiral formulae for the masses and decay constants.
Cossu, Guido; Fukaya, Hidenori; Hashimoto, Shoji; Kaneko, Takashi; Noaki, Jun-Ichi
2016-09-01
We compute the chiral condensate in 2 + 1-flavor QCD through the spectrum of low-lying eigenmodes of the Dirac operator. The number of eigenvalues of the Dirac operator is evaluated using a stochastic method with an eigenvalue filtering technique on the background gauge configurations generated by lattice QCD simulations including the effects of dynamical up, down, and strange quarks described by the Möbius domain-wall fermion formulation. The low-lying spectrum is related to the chiral condensate, which is one of the leading-order low-energy constants in chiral effective theory, as dictated by the Banks-Casher relation. The spectrum shape and its dependence on the sea quark masses calculated in numerical simulations are consistent with the expectation from one-loop chiral perturbation theory. After taking the chiral limit as well as the continuum limit using the data at three lattice spacings in the range 0.080-0.045 fm, we obtain Σ(2 GeV) = 270.0(4.9) MeV, with the error combining those from statistical and various sources of systematic error. The finite volume effect is confirmed to be under control by a direct comparison of the results from two different volumes at the lightest available sea quarks corresponding to 230 MeV pions.
Baryons in the unquenched quark model
Bijker, R; Lopez-Ruiz, M A; Santopinto, E
2016-01-01
In this contribution, we present the unquenched quark model as an extension of the constituent quark model that includes the effects of sea quarks via a $^{3}P_{0}$ quark-antiquark pair-creation mechanism. Particular attention is paid to the spin and flavor content of the proton, magnetic moments and $\\beta$ decays of octet baryons.
Inhomogeneous phases in the quark-meson model with vacuum fluctuations
Carignano, Stefano; Schaefer, Bernd-Jochen
2014-01-01
Inhomogeneous chiral-symmetry breaking phases at non-vanishing chemical potential and temperature are studied within a two-flavor quark-meson model in the chiral limit. The analysis is performed beyond the standard mean-field approximation by taking into account the Dirac-sea contributions of the quarks. Compared with the case where the Dirac sea is neglected, we find that the inhomogeneous phase shrinks, but in general does not disappear. It is shown within a Ginzburg-Landau analysis that the Lifshitz point of the inhomogeneous phase coincides with the tricritical point if the ratio between sigma-meson and constituent quark mass in vacuum is chosen to be $m_\\sigma/M = 2$, corresponding to the fixed mass ratio in the Nambu--Jona-Lasinio model. In the present model, however, this ratio can be varied, offering the possibility to separate the two points. This is confirmed by our numerical calculations, which demonstrate a strong sensitivity of the size of the inhomogeneous phase on $m_\\sigma$. Finally, we uncove...
Strange and charm quark spins from the anomalous Ward identity
Gong, Ming; Yang, Yi-Bo; Liang, Jian; Alexandru, Andrei; Draper, Terrence; Liu, Keh-Fei; χQCD Collaboration
2017-06-01
We present a calculation of the strange and charm quark contributions to the nucleon spin from the anomalous Ward identity (AWI). This is performed with overlap valence quarks on 2 +1 -flavor domain-wall fermion gauge configurations on a 2 43×64 lattice with lattice spacing a-1=1.73 GeV and the light sea mass at mπ=330 MeV . To satisfy the AWI, the overlap fermion for the pseudoscalar density and the overlap Dirac operator for the topological density, which do not have multiplicative renormalization, are used to normalize the form factor of the local axial-vector current at finite q2. For the charm quark, we find that the negative pseudoscalar term almost cancels the positive topological term. For the strange quark, the pseudoscalar term is less negative than that of the charm. By imposing the AWI, the strange gA(q2) at q2=0 is obtained by a global fit of the pseudoscalar and the topological form factors, together with gA(q2) and the induced pseudoscalar form factor hA(q2) at finite q2. The chiral extrapolation to the physical pion mass gives Δ s +Δ s ¯=-0.0403 (44 )(78 ).
Measurement of the LIght Quark Flavor Asymmetry in the Nucleon Sea
Energy Technology Data Exchange (ETDEWEB)
Peng, J.C.; Awes, T.C.; Beddo, M.E.; Brooks, M.L.; Brown, C.N.; Bush, J.D.; Carey, T.A.; Chang, T.H.; Cooper, W.E.; Gagliardi, C.A.; Garvey, G.T.; Geesaman, D.F.; Hawker, E.A.; He, X.C.; Isenhower, L.D.; Kaufman, S.B.; Kaplan, D.M.; Kirk, P.N.; Koetke, D.D.; Kyle, G.; Lee, D.M.; Lee, W.M.; Leitch, M.J.; Makins, N.; McGaughey, P.L.; Moss, J.M.; Mueller, B.A.; Nord, P.M.; Park, B.K.; Papavassiliou, V.; Petitt, G.; Reimer, P.E.; Sadler, M.E.; Stankus, P.W.; Sondheim, W.E.; Thompson, T.N.; Towell, R.S.; Tribble, R.E.; Vasiliev, M.A.; Wang, Y.C.; Wang, Z.F.; Webb, J.C.; Willis, J.L.; Wise, D.K.; Young, G.R.
1998-07-23
The Drell-Yan cross section ratios, s(p+d)/s(p+p), measured in Fermilab E866, have led to the first determination of d(x)/u(x), d(x)-(x), and the integral of d(x)-u(x) for the proton over the range 0.02 < x < 0.345. The E866 results are compared with predictions based on parton distribution functions and various theoretical models. The relationship between the E866 results and the NMC measurements of the Gottfried integral is discussed. The agreement between the E866 results and models employing virtual mesons indicates these non-perturbative processes play an important role in the origin of the d, u asymmetry in the nucleon sea.
Renormalization of Dirac's Polarized Vacuum
Lewin, Mathieu
2010-01-01
We review recent results on a mean-field model for relativistic electrons in atoms and molecules, which allows to describe at the same time the self-consistent behavior of the polarized Dirac sea. We quickly derive this model from Quantum Electrodynamics and state the existence of solutions, imposing an ultraviolet cut-off $\\Lambda$. We then discuss the limit $\\Lambda\\to\\infty$ in detail, by resorting to charge renormalization.
Supersymmetry in 6d Dirac Action
Fujimoto, Yukihiro; Nishiwaki, Kenji; Sakamoto, Makoto; Tatsumi, Kentaro
2016-01-01
We investigate a 6d Dirac fermion on a rectangle. It is found that the 4d spectrum is governed by $N = 2$ supersymmetric quantum mechanics. Then we demonstrate that the supersymmetry is very useful to classify all allowed boundary conditions and to expand the 6d Dirac field in Kaluza-Klein modes. A striking feature of the model is that even though the 6d Dirac fermion has non-vanishing bulk mass, the 4d mass spectrum can contain degenerate massless chiral fermions, which may provide a hint to solve the generation problem of the quarks and leptons. It is pointed out that zero energy solutions are not affected by the presence of the boundaries, while the boundary conditions work well for determining the positive energy solutions.
One-loop renormalization of fermionic currents with the overlap-Dirac operator
Alexandrou, C; Panagopoulos, H; Vicari, E
2000-01-01
We compute the one-loop lattice renormalization of the two-quark operators$\\bar{\\psi} \\Gamma \\psi$, where $\\Gamma$ denotes the generic Dirac matrix, forthe lattice formulation of QCD using the overlap-Dirac operator. We also study the renormalization of quark bilinears which are more extendedand have better chiral properties. Finally, we present improved estimates of these renormalization constants,coming from cactus resummation and from mean field perturbation theory.
Two-loop anomalous dimensions for currents of baryons with two heavy quarks in NRQCD
Kiselev, V V
1998-01-01
We present analytical results on the two-loop anomalous dimensions of currents for baryons, containing two heavy quarks $J = [Q^{iT}C\\Gamma\\tau Q^j]\\Gamma' q^k\\epsilon_{ijk}$ with arbitrary Dirac matrices $\\Gamma$ and velocity of heavy quarks and the inverse heavy quark mass. It is shown, that in this approximation the anomalous dimensions do not depend on the Dirac structure of the current under consideration.
High temperature quark localization by Polyakov loops
Kovacs, Tamas G; Bruckmann, Falk; Schierenberg, Sebastian
2011-01-01
We study the low eigenmodes of the overlap and staggered Dirac operator at high temperature. We show that the recently found localized quark modes obeying Poisson statistics are connected to physical gauge field objects with their size and density scaling in the continuum limit. The localized modes are also strongly correlated with large fluctuations of the Polyakov loop. Based on that we construct a random matrix model of the low Dirac modes inspired by dimensional reduction. Our model reproduces the Poisson to random matrix transition seen in the lattice Dirac spectrum.
DIRAC distributed secure framework
Casajus, A.; Graciani, R.; LHCb DIRAC Team
2010-04-01
DIRAC, the LHCb community Grid solution, provides access to a vast amount of computing and storage resources to a large number of users. In DIRAC users are organized in groups with different needs and permissions. In order to ensure that only allowed users can access the resources and to enforce that there are no abuses, security is mandatory. All DIRAC services and clients use secure connections that are authenticated using certificates and grid proxies. Once a client has been authenticated, authorization rules are applied to the requested action based on the presented credentials. These authorization rules and the list of users and groups are centrally managed in the DIRAC Configuration Service. Users submit jobs to DIRAC using their local credentials. From then on, DIRAC has to interact with different Grid services on behalf of this user. DIRAC has a proxy management service where users upload short-lived proxies to be used when DIRAC needs to act on behalf of them. Long duration proxies are uploaded by users to a MyProxy service, and DIRAC retrieves new short delegated proxies when necessary. This contribution discusses the details of the implementation of this security infrastructure in DIRAC.
Neutrinos Are Nearly Dirac Fermions
Cahill, K E
1999-01-01
Neutrino masses and mixings are analyzed in terms of left-handed fields and a 6x6 complex symmetric mass matrix whose singular values are the neutrino masses. An angle theta_nu characterizes the kind of the neutrinos, with theta_nu = 0 for Dirac neutrinos and theta_nu = pi/2 for Majorana neutrinos. If theta_nu = 0, then baryon-minus-lepton number is conserved. When theta_nu is approximately zero, the six neutrino masses coalesce into three nearly degenerate pairs. Thus the smallness of the differences in neutrino masses exhibited in the solar and atmospheric neutrino experiments and the stringent limits on neutrinoless double-beta decay are naturally explained if B-L is approximately conserved and neutrinos are nearly Dirac fermions. If one sets theta_nu = 0.0005, suppresses inter-generational mixing, and imposes a quark-like mass hierarchy, then one may fit the essential features of the solar, reactor, and atmospheric neutrino experiments with otherwise random mass matrices in the eV range. This B-L model le...
Photoconductivity in Dirac materials
Directory of Open Access Journals (Sweden)
J. M. Shao
2015-11-01
Full Text Available Two-dimensional (2D Dirac materials including graphene and the surface of a three-dimensional (3D topological insulator, and 3D Dirac materials including 3D Dirac semimetal and Weyl semimetal have attracted great attention due to their linear Dirac nodes and exotic properties. Here, we use the Fermi’s golden rule and Boltzmann equation within the relaxation time approximation to study and compare the photoconductivity of Dirac materials under different far- or mid-infrared irradiation. Theoretical results show that the photoconductivity exhibits the anisotropic property under the polarized irradiation, but the anisotropic strength is different between 2D and 3D Dirac materials. The photoconductivity depends strongly on the relaxation time for different scattering mechanism, just like the dark conductivity.
Photoconductivity in Dirac materials
Energy Technology Data Exchange (ETDEWEB)
Shao, J. M.; Yang, G. W., E-mail: stsygw@mail.sysu.edu.cn [State Key Laboratory of Optoelectronic Materials and Technologies, Nanotechnology Research Center, School of Materials & Engineering, School of Physics & Engineering, Sun Yat-sen University, Guangzhou 510275, Guangdong (China)
2015-11-15
Two-dimensional (2D) Dirac materials including graphene and the surface of a three-dimensional (3D) topological insulator, and 3D Dirac materials including 3D Dirac semimetal and Weyl semimetal have attracted great attention due to their linear Dirac nodes and exotic properties. Here, we use the Fermi’s golden rule and Boltzmann equation within the relaxation time approximation to study and compare the photoconductivity of Dirac materials under different far- or mid-infrared irradiation. Theoretical results show that the photoconductivity exhibits the anisotropic property under the polarized irradiation, but the anisotropic strength is different between 2D and 3D Dirac materials. The photoconductivity depends strongly on the relaxation time for different scattering mechanism, just like the dark conductivity.
Overlap Quark Propagator in Coulomb Gauge QCD
Mercado, Ydalia Delgado; Schröck, Mario
2014-01-01
The chirally symmetric Overlap quark propagator is explored in Coulomb gauge. This gauge is well suited for studying the relation between confinement and chiral symmetry breaking, since confinement can be attributed to the infrared divergent Lorentz-vector dressing function. Using quenched gauge field configurations on a $20^4$ lattice, the quark propagator dressing functions are evaluated, the dynamical quark mass is extracted and the chiral limit of these quantities is discussed. By removing the low-lying modes of the Dirac operator, chiral symmetry is artificially restored. Its effect on the dressing functions is discussed.
Energy Technology Data Exchange (ETDEWEB)
Rodrigues, R. de Lima [Universidade Federal de Campina Grande (UFCG), Cuite, PB (Brazil). Centro de Tecnologia. Unidade Academica de Educacao]. E-mail: rafael@df.ufcg.edu.br; rafaelr@cbpf.br
2007-07-01
In the present work we obtain a new representation for the Dirac oscillator based on the Clifford algebra C 7. The symmetry breaking and the energy eigenvalues for our model of the Dirac oscillator are studied in the non-relativistic limit. (author)
Monti, Dalida
1996-01-01
Relativamente poco noto al gran pubblico, il premio Nobel Paul Adrien Maurice Dirac appartiene a quel gruppo di uomini di ingegno che nei primi decenni del secolo contribuirono a dare alla nostra concezione del mondo fisico la sua impronta attuale. Assolutamente cruciali, per una valutazione dell'opera di Dirac, sono gli anni compresi tra il 1925 e il 1931: un periodo in cui il fisico fornisce la prima spiegazione chiara e coerente delle proprietà di spin dell'elettrone (equazione di Dirac) e perviene, in forza della pura deduzione matematica, alla scoperta dell'esistenza dell'elettrone positivo o positrone.
Extended Quark Potential Model From Random Phase Approximation
Institute of Scientific and Technical Information of China (English)
DENGWei－Zhen; CHENXiao－Lin; 等
2002-01-01
The quark potential model is extended to include the sea quark excitation using the random phase approximation.The effective quark interaction preserves the important QCD properties-chiral symmetry and confinement simultaneously.A primary qualitative analysis shows that the π meson as a well-known typical Goldstone boson and the other mesons made up of valence qq quark pair such as the ρ meson can also be described in this extended quark potential model.
Unquenching effects in the quark and gluon propagator
Kamleh, Waseem; Bowman, Patrick O.; Leinweber, Derek B.; Williams, Anthony G.; Zhang, Jianbo
2007-11-01
In this work we examine the fat-link irrelevant clover (FLIC) overlap quark propagator and the gluon propagator on both dynamical and quenched lattices. The tadpole-improved Luscher-Weisz gauge action is used in both cases. The dynamical gauge fields use the FLIC fermion action for the sea quark contribution. We observe that the presence of sea quarks causes a suppression of the mass function, quark renormalization function, and gluon dressing function in the infrared. The ultraviolet physics is unaffected.
Three dimensional Dirac semimetals
Zaheer, Saad
We extend the physics of graphene to three dimensional systems by showing that Dirac points can exist on the Fermi surface of realistic materials in three dimensions. Many of the exotic electronic properties of graphene can be ascribed to the pseudorelativistic behavior of its charge carriers due to two dimensional Dirac points on the Fermi surface. We show that certain nonsymmorphic spacegroups exhibit Dirac points among the irreducible representations of the appropriate little group at high symmetry points on the surface of the Brillouin zone. We provide a list of all Brillouin zone momenta in the 230 spacegroups that can host Dirac points. We describe microscopic considerations necessary to design materials in one of the candidate spacegroups such that the Dirac point appears at the Fermi energy without any additional non-Dirac-like Fermi pockets. We use density functional theory based methods to propose six new Dirac semimetals: BiO 2 and SbO2 in the beta-cristobalite lattice (spacegroup 227), and BiCaSiO4, BiMgSiO4, BiAlInO 4, and BiZnSiO4 in the distorted spinels lattice (spacegroup 74). Additionally we derive effective Dirac Hamiltonians given group representative operators as well as tight binding models incorporating spin-orbit coupling. Finally we study the Fermi surface of zincblende (spacegroup 216) HgTe which is effectively point-like at Gamma in the Brillouin zone and exhibits accidental degeneracies along a threefold rotation axis. Whereas compressive strain gaps the band structure into a topological insulator, tensile strain shifts the accidental degeneracies away from Gamma and enlarges the Fermi surface. States on the Fermi surface exhibit nontrivial spin texture marked by winding of spins around the threefold rotation axis and by spin vortices indicating a change in the winding number. This is confirmed by microscopic calculations performed in tensile strained HgTe and Hg0.5Zn 0.5 Te as well as k.p theory. We conclude with a summary of recent
DIRAC Workload Management System
Paterson, S
2007-01-01
DIRAC (Distributed Infrastructure with Remote Agent Control) is the Workload and Data Management system (WMS) for the LHCb experiment. The DIRAC WMS offers a transparent way for LHCb users to submit jobs to the EGEE Grid as well as local clusters and individual PCs. This paper will describe workload management optimizations, which ensure high job efficiency and minimized job start times. The computing requirements of the LHCb experiment can only be fulfilled through the use of many distributed compute resources. DIRAC provides a robust platform to run data productions on all the resources available to LHCb including the EGEE Grid. More recently, user support was added to DIRAC that greatly simplifies the procedure of submitting, monitoring and retrieving output of Grid jobs for the LHCb user community. DIRAC submits Pilot Agents to the EGEE Grid via the gLite WMS as normal jobs. Pilot Agents then request jobs from the DIRAC Workload Management System after the local environment has been checked. Therefore DIR...
The strange-quark distribution
Energy Technology Data Exchange (ETDEWEB)
Barone, V. [Turin Univ. (Italy). Ist. di Fisica Teorica; Genovese, M. [Turin Univ. (Italy). Ist. di Fisica Teorica]|[European Organization for Nuclear Research, Geneva (Switzerland). Theory Div.; Nikolaev, N.N. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Kernphysik]|[L.D. Landau Institute for Theoretical Physics, Moscow (Russian Federation); Predazzi, E. [Turin Univ. (Italy). Ist. di Fisica Teorica; Zakharov, B.G. [L.D. Landau Institute for Theoretical Physics, Moscow (Russian Federation)
1996-03-01
We discuss the latest CCFR determination of the strange sea density of the proton. We comment on the differences with a previous, leading-order, result and point out the relevance of quark mass effects and current non-conservation effects. By taking them into account it is possible to solve the residual discrepancy with another determination of the strange-quark distribution. Two important sources of uncertainties are also analysed. (orig.). With 4 figs.
U_A(1) breaking at finite temperature from the Dirac spectrum with the dynamical HISQ action
Ohno, H; Karsch, F; Mukherjee, S
2012-01-01
We investigate $U_A(1)$ breaking above $T_c$ in terms of the Dirac spectrum on configurations with (2+1)-flavors, using the HISQ action. The strange quark mass is at its physical value. We use several light quark masses corresponding to the Goldstone pion masses in the range of about 115 -- 230 MeV on lattices of size 32$^3 \\times$8 and 48$^3 \\times$8. We calculate the 100 lowest-lying Dirac eigenvalues at temperatures below and above $T_c$. We investigate the volume dependence of the Dirac eigenvalue density to determine whether there is a gap around zero, which can appear if $U_A(1)$ symmetry is restored in the chiral symmetric phase. We also investigate the quark mass dependence of the Dirac eigenvalue density at zero and check whether there is a linear behavior that would signal the $U_A(1)$ breaking above $T_c$.
Chiral condensate from the twisted mass Dirac operator spectrum
Cichy, Krzysztof; Jansen, Karl
2013-01-01
We present the results of our computation of the chiral condensate with $N_f=2$ and $N_f=2+1+1$ flavours of maximally twisted mass fermions. The condensate is determined from the Dirac operator spectrum, applying the spectral projector method proposed by Giusti and Luscher. We use 3 lattice spacings and several quark masses at each lattice spacing to reliably perform the chiral and continuum extrapolations. We study the effect of the dynamical strange and charm quarks by comparing our results for $N_f=2$ and $N_f=2+1+1$ dynamical flavours.
Prompt quark production by exploding sphalerons
Shuryak, Edward; Zahed, Ismail
2003-01-01
Following recent works on the production and subsequent explosive decay of QCD sphaleronlike clusters, we discuss the mechanism of quark pair production in this process. We first show how the gauge field explosive solution of Luscher and Schechter can be achieved by noncentral conformal mapping from the O(4)-symmetric solution. Our main result is a new solution to the Dirac equation in real time in this configuration, obtained by the same inversion of the fermion O(4) zero mode. It explicitly shows how the quark acceleration occurs, starting from the spherically O(3)-symmetric zero energy chiral quark state to the final spectrum of nonzero energies. The sphaleronlike clusters with any Chern-Simons number always produce NFL¯R quarks, and the antisphaleron-like clusters the opposite chirality. The result are relevant for hadron-hadron and nucleus-nucleus collisions at large (s), wherein such clusters can be produced.
Luciano Maiani and Jean Iliopoulos awarded the Dirac Medal
2007-01-01
Luciano Maiani, when he was Director-General of CERN. Jean Iliopoulos in 1999. (©CNRS Photothèque - Julien Quideau)On 8 August, the 2007 Dirac Medal, one of the most prestigious prizes in the fields of theoretical physics and mathematics, was awarded to Luciano Maiani, professor at Rome’s La Sapienza University and former Director-General of CERN, and to Jean Iliopoulos, emeritus Director of Research at the CNRS Laboratory of Theoretical Physics. The medal was awarded to both physicists for their joint "work on the physics of the charm quark, a major contribution to the birth of the Standard Model, the modern theory of Elementary Particles." Founded by the Abdus Salam International Centre for Theoretical Physics (ICTP) in 1985, the Dirac Medal is awarded annually on 8 August, the birthday of the famous physicist Paul Dirac, winner of the 1933 Nobel Prize for Physics. It is awarded to ...
Cossu, Guido; Hashimoto, Shoji; Kaneko, Takashi; Noaki, Jun-Ichi
2016-01-01
We compute the chiral condensate in 2+1-flavor QCD through the spectrum of low-lying eigenmodes of Dirac operator. The number of eigenvalues of the Dirac operator is evaluated using a stochastic method with an eigenvalue filtering technique on the background gauge configurations generated by lattice QCD simulations including the effects of dynamical up, down and strange quarks described by the Mobius domain-wall fermion formulation. The low-lying spectrum is related to the chiral condensate, which is one of the leading order low-energy constants in chiral effective theory, as dictated by the Banks-Casher relation. The spectrum shape and its dependence on the sea quark masses calculated in numerical simulations are consistent with the expectation from one-loop chiral perturbation theory. After taking the chiral limit as well as the continuum limit using the data at three lattice spacings ranging 0.080-0.045 fm, we obtain $\\Sigma^{1/3}$(2 GeV) = 270.0(4.9) MeV, with the error combining those from statistical an...
Structure of Dirac matrices and invariants for nonlinear Dirac equations
2004-01-01
We present invariants for nonlinear Dirac equations in space-time ${\\mathbb R}^{n+1}$, by which we prove that a special choice of the Cauchy data yields free solutions. Our argument works for Klein-Gordon-Dirac equations with Yukawa coupling as well. Related problems on the structure of Dirac matrices are studied.
Institute of Scientific and Technical Information of China (English)
LI Zi-Ping; LI Ai-Min; JIANG Jin-Huan; WANG Yong-Long
2005-01-01
The extended canonical Noether identities and canonical first Noether theorem derived from an extended action in phase space for a system with a singular Lagrangian are formulated. Using these canonical Noether identities,it can be shown that the constraint multipliers connected with the first-class constraints may not be independent, so a query to a conjecture of Dirac is presented. Based on the symmetry properties of the constrained Hamiltonian system in phase space, a counterexample to a conjecture of Dirac is given to show that Dirac's conjecture fails in such a system.We present here a different way rather than Cawley's examples and other's ones in that there is no linearization of constraints in the problem. This example has a feature that neither the primary first-class constraints nor secondary first-class constraints are generators of the gauge transformation.
Dressed Quarks and PROTON’S Spin
Yang, Xin-Hua; Wong, Chun Wa; Chu, Keh-Cheng
The effect on the proton spin of mixing gluon and sea quark configurations is studied in a perturbative treatment based on the MIT bag model. As little as 29% of the proton spin is found to remain as the intrinsic spin of quarks when they are “dressed” by gluons.
A Timeon Model of Quark and Lepton Mass Matrices
Friedberg, R
2009-01-01
It is proposed that $T$ violation in physics, as well as the masses of electron and $u, d$ quarks, arise from a pseudoscalar interaction with a new spin 0 field $\\tau(x)$, odd in $P$ and $T$, but even in $C$. This interaction contains a factor $i\\gamma_5$ in the quark and lepton Dirac algebra, so that the full Hamiltonian is $P$, $T$ conserving; but by spontaneous symmetry breaking, the new field $\\tau(x)$ has a nonzero expectation value $\
Dirac Induction for loop groups
Posthuma, H.
2011-01-01
Using a coset version of the cubic Dirac operators for affine Lie algebras, we give an algebraic construction of the Dirac induction homomorphism for loop group representations. With this, we prove a homogeneous generalization of the Weyl-Kac character formula and show compatibility with Dirac induc
Quark Models and Quark Phenomenology
Lipkin, Harry Jeannot
1997-01-01
Overwhelming experimental evidence for quarks as real physical constituents of hadrons along with the QCD analogs of the Balmer Formula, Bohr Atom and Schroedinger Equation already existed in 1966. A model of colored quarks interacting with a one-gluon-exchange potential explained the systematics of the meson and baryon spectrum and gave a hadron mass formula in surprising agreement with experiment. The simple quark model dismissed as heresy and witchcraft by the establishment predicted quantum numbers of an enormous number of hadronic states as well as relations between masses, reaction cross sections and electromagnetic properties, all unexplained by other approaches. Further developments leading to QCD included confinement in the large $N_c$ limit, duality, dual resonance and string models, high energy scattering systematics, unified treatment of mesons and baryons, no exotics and no free quarks.
Dirac equation in low dimensions: The factorization method
Energy Technology Data Exchange (ETDEWEB)
Sánchez-Monroy, J.A., E-mail: antosan@if.usp.br [Instituto de Física, Universidade de São Paulo, 05508-090, São Paulo, SP (Brazil); Quimbay, C.J., E-mail: cjquimbayh@unal.edu.co [Departamento de Física, Universidad Nacional de Colombia, Bogotá, D. C. (Colombia); CIF, Bogotá (Colombia)
2014-11-15
We present a general approach to solve the (1+1) and (2+1)-dimensional Dirac equations in the presence of static scalar, pseudoscalar and gauge potentials, for the case in which the potentials have the same functional form and thus the factorization method can be applied. We show that the presence of electric potentials in the Dirac equation leads to two Klein–Gordon equations including an energy-dependent potential. We then generalize the factorization method for the case of energy-dependent Hamiltonians. Additionally, the shape invariance is generalized for a specific class of energy-dependent Hamiltonians. We also present a condition for the absence of the Klein paradox (stability of the Dirac sea), showing how Dirac particles in low dimensions can be confined for a wide family of potentials. - Highlights: • The low-dimensional Dirac equation in the presence of static potentials is solved. • The factorization method is generalized for energy-dependent Hamiltonians. • The shape invariance is generalized for energy-dependent Hamiltonians. • The stability of the Dirac sea is related to the existence of supersymmetric partner Hamiltonians.
Directory of Open Access Journals (Sweden)
P. G. L. Leach
2014-04-01
Full Text Available Dirac devised his theory of Quantum Mechanics and recognised that his operators resembled the canonical coordinates of Hamiltonian Mechanics. This gave the latter a new lease of life. We look at what happens to Dirac’s Quantum Mechanics if one starts from Hamiltonian Mechanics.
Trzetrzelewski, Maciej
2011-01-01
In c=1 units the product (mass x radius) for the neutron and the proton is about 4.7\\hbar assuming their radii equal to 1fm. We show that the corresponding products for the Dirac neutral and charged membrane coincide and are equal 1.6\\hbar.
Guignard, G
2005-01-01
The DIRAC project aims to the design and development of one of the key aspects of the international Facility for Antiproton and Ion Research (FAIR) planned for construction at GSI in Darmstadt, Germany: the broad implementation and optimization of ion storage/cooler rings and of in-ring experimentation with internal targets and secondary beams.
Dirac equation in low dimensions: The factorization method
Sánchez-Monroy, J. A.; Quimbay, C. J.
2014-11-01
We present a general approach to solve the (1 + 1) and (2 + 1) -dimensional Dirac equations in the presence of static scalar, pseudoscalar and gauge potentials, for the case in which the potentials have the same functional form and thus the factorization method can be applied. We show that the presence of electric potentials in the Dirac equation leads to two Klein-Gordon equations including an energy-dependent potential. We then generalize the factorization method for the case of energy-dependent Hamiltonians. Additionally, the shape invariance is generalized for a specific class of energy-dependent Hamiltonians. We also present a condition for the absence of the Klein paradox (stability of the Dirac sea), showing how Dirac particles in low dimensions can be confined for a wide family of potentials.
Thermal Recombination: Beyond the Valence Quark Approximation
Müller, B; Bass, S A
2005-01-01
Quark counting rules derived from recombination models agree well with data on hadron production at intermediate transverse momenta in relativistic heavy-ion collisions. They convey a simple picture of hadrons consisting only of valence quarks. We discuss the inclusion of higher Fock states that add sea quarks and gluons to the hadron structure. We show that, when recombination occurs from a thermal medium, hadron spectra remain unaffected by the inclusion of higher Fock states. However, the quark number scaling for elliptic flow is somewhat affected. We discuss the implications for our understanding of data from the Relativistic Heavy Ion Collider.
Pseudoscalar meson physics with four dynamical quarks
Bazavov, A; Bouchard, C; DeTar, C; Du, D; El-Khadra, A X; Foley, J; Freeland, E D; Gamiz, E; Gottlieb, Steven; Heller, U M; Hetrick, J E; Kim, J; Kronfeld, A S; Laiho, J; Levkova, L; Lightman, M; Mackenzie, P B; Neil, E T; Oktay, M; Simone, J N; Sugar, R L; Toussaint, D; Van de Water, R S; Zhou, R
2012-01-01
We present preliminary results for light, strange and charmed pseudoscalar meson physics from simulations using four flavors of dynamical quarks with the highly improved staggered quark (HISQ) action. These simulations include lattice spacings ranging from 0.15 to 0.06 fm, and sea-quark masses both above and at their physical value. The major results are charm meson decay constants f_D, f_{D_s} and f_{D_s}/f_D and ratios of quark masses. This talk will focus on our procedures for finding the decay constants on each ensemble, the continuum extrapolation, and estimates of systematic error.
Extended Quark Potential Model from Random Phase Approximation
Institute of Scientific and Technical Information of China (English)
DENG Wei-Zhen; CHEN Xiao-Lin; LU Da-Hai; YANG Li-Ming
2002-01-01
The quark potential model is extended to include the sea quark excitation using the random phase approx-imation. The effective quark interaction preserves the important QCD properties - chiral symmetry and confinementsimultaneously. A primary qualitative analysis shows that the π meson as a well-known typical Goldstone boson andthe other mesons made up of valence qq quark pair such as the ρ meson can also be described in this extended quarkpotential model.
Statistical Quark Model for the Nucleon Structure Function
Mirez, Carlos; Tomio, Lauro; Trevisan, Luis A.; Frederico, Tobias
2009-06-01
A statistical quark model, with quark energy levels given by a central linear confining potential is used to obtain the light sea-quark asymmetry, d¯/ū, and also for the ratio d/u, inside the nucleon. After adjusting a temperature parameter by the Gottfried sum rule violation, and chemical potentials by the valence up and down quark normalizations, the results are compared with experimental data available.
A detailed study of nonperturbative solutions of two-body Dirac equations
Energy Technology Data Exchange (ETDEWEB)
Crater, H.W.; Becker, R.L.; Wong, C.Y.; Van Alstine, P.
1992-12-01
In quark model calculations of the meson spectrums fully covariant two-body Dirac equations dictated by Dirac's relativistic constraint mechanics gave a good fit to the entire meson mass spectrum for light quark mesons as well as heavy quark mesons with constituent world scalar and vector potentials depending on just one or two parameters. In this paper, we investigate the properties of these equations that made them work so well by solving them numerically for quantum electrodynamics (QED) and related field theories. The constraint formalism generates a relativistic quantum mechanics defined by two coupled Dirac equations on a sixteen component wave function which contain Lorentz covariant constituent potentials that are initially undetermined. An exact Pauli reduction leads to a second order relativistic Schroedinger-like equation for a reduced eight component wave function determined by an effective interaction -- the quasipotential. We first determine perturbatively to lowest order the relativistic quasipotential for the Schroedinger-like equation by comparing that form with one derived from the Bethe-Salpeter equation. Insertion of this perturbative information into the minimal interaction structures of the two-body Dirac equations then completely determines their interaction structures. Then we give a procedure for constructing the full sixteen component solution to our coupled first-order Dirac equations from a solution of the second order equation for the reduced wave function. Next, we show that a perturbative treatment of these equations yields the standard spectral results for QED and related interactions.
Hydrodynamics of the Chiral Dirac Spectrum
Liu, Yizhuang; Zahed, Ismail
2016-01-01
We derive a hydrodynamical description of the eigenvalues of the chiral Dirac spectrum in the vacuum and in the large $N$ (volume) limit. The linearized hydrodynamics supports sound waves. The stochastic relaxation of the eigenvalues is captured by a hydrodynamical instanton configuration which follows from a pertinent form of Euler equation. The relaxation from a phase of localized eigenvalues and unbroken chiral symmetry to a phase of de-localized eigenvalues and broken chiral symmetry occurs over a time set by the speed of sound. We show that the time is $\\Delta \\tau=\\pi\\rho(0)/2\\beta N$ with $\\rho(0)$ the spectral density at zero virtuality and $\\beta=1,2,4$ for the three Dyson ensembles that characterize QCD with different quark representations in the ergodic regime.
Menke, Sven; The ATLAS collaboration
2017-01-01
The top quark is the heaviest known fundamental particle. As it is the only quark that decays before it hadronises, analyses of events containing top quarks allow to probe the properties of bare quarks and to test perturbative QCD. This talk will focus on recent precision top-quark measurements by the ATLAS Collaboration: Single top-quark and top-quark pair production cross sections including differential distributions will be presented, as well as measurements of top-quark pair production in association with a W or Z boson and measurements of top quark properties such as the spin correlation and W boson helicity in top quark pair events.
Generalized Lorentz-Dirac equation for a strongly coupled gauge theory.
Chernicoff, Mariano; García, J Antonio; Güijosa, Alberto
2009-06-19
We derive a semiclassical equation of motion for a "composite" quark in strongly coupled large-N_{c} N = 4 super Yang-Mills theory, making use of the anti-de Sitter space/conformal field theory correspondence. The resulting nonlinear equation incorporates radiation damping, and reduces to the standard Lorentz-Dirac equation for external forces that are small on the scale of the quark Compton wavelength, but has no self-accelerating or preaccelerating solutions. From this equation one can read off a nonstandard dispersion relation for the quark, as well as a Lorentz-covariant formula for its radiation rate.
Directory of Open Access Journals (Sweden)
Wei Khim Ng
2009-02-01
Full Text Available We construct nonlinear extensions of Dirac's relativistic electron equation that preserve its other desirable properties such as locality, separability, conservation of probability and Poincaré invariance. We determine the constraints that the nonlinear term must obey and classify the resultant non-polynomial nonlinearities in a double expansion in the degree of nonlinearity and number of derivatives. We give explicit examples of such nonlinear equations, studying their discrete symmetries and other properties. Motivated by some previously suggested applications we then consider nonlinear terms that simultaneously violate Lorentz covariance and again study various explicit examples. We contrast our equations and construction procedure with others in the literature and also show that our equations are not gauge equivalent to the linear Dirac equation. Finally we outline various physical applications for these equations.
Renormalisation constants of quark bilinears in lattice QCD with four dynamical Wilson quarks
Blossier, B.; Brinet, M.; Carrasco, N.; Dimopoulos, P.; Du, X.; Frezzotti, R.; Gimenez, V.; Herdoiza, G.; Jansen, K.; Lubicz, V.; Palao, D.; Pallante, E.; Pene, O.; Petrov, K.; Reker, S.; Rossi, G. C.; Sanfilippo, F.; Scorzato, L.; Simula, S.; Urbach, C.
2011-01-01
We present preliminary results of the non-perturbative computation of the RI-MOM renormalisation constants in a mass-independent scheme for the action with Iwasaki glue and four dynamical Wilson quarks employed by ETMC. Our project requires dedicated gauge ensembles with four degenerate sea quark
DIRAC Workload Management System
Garonne, V; Stokes-Rees, I
2005-01-01
The Workload Management System is the core component of the DIRAC distributed MC production and analysis grid environment of the CERN LHCb experiment. This paper discusses the architecture, implementation and performance of this system. The WMS is a community scheduler, realizing a pull paradigm, particulary for the high troughput computing context. It has recently been used for an intensive physics simulation production involving more than 60 sites, 65 TB of data, and over 1000-GHz processor-years.
Trzetrzelewski, Maciej
2016-11-01
Starting with a Nambu-Goto action, a Dirac-like equation can be constructed by taking the square-root of the momentum constraint. The eigenvalues of the resulting Hamiltonian are real and correspond to masses of the excited string. In particular there are no tachyons. A special case of radial oscillations of a closed string in Minkowski space-time admits exact solutions in terms of wave functions of the harmonic oscillator.
Unquenched QCD with Light Quarks
Duncan, A; Yoo, J
2003-01-01
We present recent results in unquenched lattice QCD with two degenerate light sea quarks using the truncated determinant approximation (TDA). In the TDA the infrared modes contributing to the quark determinant are computed exactly up to some cutoff in quark off-shellness (typically 2$\\Lambda_{QCD}$). This approach allows simulations to be performed at much lighter quark masses than possible with conventional hybrid MonteCarlo techniques. Results for the static energy and topological charge distributions are presented using a large ensemble generated on very coarse (6$^4$) but physically large lattices. Preliminary results are also reported for the static energy and meson spectrum on 10$^3$x20 lattices (lattice scale $a^{-1}$=1.15 GeV) at quark masses corresponding to pions of mass $\\leq$ 200 MeV. Using multiboson simulation to compute the ultraviolet part of the quark determinant the TDA approach becomes an exact with essentially no increase in computational effort. Some preliminary results using this fully u...
Aloisi, A.M.; Nali, P. F.
2016-01-01
In 1931, Dirac advanced a startling prediction about the existence of a new elementary particle, characterized by a magnetic charge of a single polarity: the magnetic monopole. This prediction, that was not based on experimental reasons but on mathematical consistency considerations and the generalization of the formalism of quantum mechanics, illustrates emblematically the Dirac conception of the relationship between physics and mathematics. ----- Nel 1931 Dirac avanz\\`o una sorprendente pre...
Octet baryon mass splittings from up-down quark mass differences
Horsley, R; Nakamura, Y; Pleiter, D; Rakow, P E L; Schierholz, G; Zanotti, J M
2012-01-01
Using an SU(3) flavour symmetry breaking expansion in the quark mass, we determine the QCD component of the neutron-proton, Sigma and Xi mass splittings of the baryon octet due to up-down (and strange) quark mass differences. Provided the average quark mass is kept constant, the expansion coefficients in our procedure can be determined from computationally cheaper simulations with mass degenerate sea quarks and partially quenched valence quarks. Full details and numerical results are given in ref 1.
Bhatnagar, Shashank; Mengesha, Yikdem
2013-01-01
In this work we have employed Bethe-Salpeter equation (BSE) under covariant instantaneous ansatz (CIA) to study electromagnetic decays of ground state equal mass vector mesons: $\\rho$, $\\omega$, $\\phi$, $\\psi$ and $Y$ through the process $V\\rightarrow\\gamma*\\rightarrow e^+ + e^-$. We employ the generalized structure of hadron-quark vertex function $\\Gamma$ which incorporates various Dirac structures from their complete set order-by-order in powers of inverse of meson mass. The electromagnetic decay constants for the above mesons are calculated using the leading order (LO) and the next-to-leading order (NLO) Dirac structures. The relevance of various Dirac structures in this calculation is studied.
Equivalence of Matrix Models for Complex QCD Dirac Spectra
Akemann, G
2003-01-01
Two different matrix models for QCD with a non-vanishing quark chemical potential are shown to be equivalent by mapping the corresponding partition functions. The equivalence holds in the phase with broken chiral symmetry. It is exact in the limit of weak non-Hermiticity, where the chemical potential squared is rescaled with the volume. At strong non-Hermiticity it holds only for small chemical potential. The first model proposed by Stephanov is directly related to QCD and allows to analyze the QCD phase diagram. In the second model suggested by the author all microscopic spectral correlation functions of complex Dirac operators can be calculated in the broken phase. We briefly compare those predictions to complex Dirac eigenvalues from quenched QCD lattice simulations.
LHCb: DIRAC Secure Distributed Platform
Casajus, A
2009-01-01
DIRAC, the LHCb community grid solution, provides access to a vast amount of computing and storage resources to a large number of users. In DIRAC users are organized in groups with different needs and permissions. In order to ensure that only allowed users can access the resources and to enforce that there are no abuses, security is mandatory. All DIRAC services and clients use secure connections that are authenticated using certificates and grid proxies. Once a client has been authenticated, authorization rules are applied to the requested action based on the presented credentials. These authorization rules and the list of users and groups are centrally managed in the DIRAC Configuration Service. Users submit jobs to DIRAC using their local credentials. From then on, DIRAC has to interact with different Grid services on behalf of this user. DIRAC has a proxy management service where users upload short-lived proxies to be used when DIRAC needs to act on behalf of them. Long duration proxies are uploaded by us...
Effects of dynamical FLIC fermions in the quark and gluon propagator
Kamleh, W.; Bowman, P. O.; Leinweber, D. B.; Williams, A. G.; Zhang, J.-B.
2006-11-01
In this work we examine the FLIC overlap quark propagator and the gluon propagator on both dynamical and quenched lattices. The tadpole improved Luscher-Weisz gauge action is used in both cases. The dynamical gauge fields use the FLIC fermion action for the sea quark contribution. We observe that the presence of sea quarks causes a suppression of the mass function, quark renormalisation function and gluon dressing function in the infrared. The ultraviolet physics is unaffected.
Exploring quark transverse momentum distributions with lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Bernhard U. Musch, Philipp Hagler, John W. Negele, Andreas Schafer
2011-05-01
We discuss in detail a method to study transverse momentum dependent parton distribution functions (TMDs) using lattice QCD. To develop the formalism and to obtain first numerical results, we directly implement a bi-local quark-quark operator connected by a straight Wilson line, allowing us to study T-even, "process-independent" TMDs. Beyond results for x-integrated TMDs and quark densities, we present a study of correlations in x and transverse momentum. Our calculations are based on domain wall valence quark propagators by the LHP collaboration calculated on top of gauge configurations provided by MILC with 2+1 flavors of asqtad-improved staggered sea quarks.
Study of u and d quark form factors in light front wave function with N{sup 2}LO approximation
Energy Technology Data Exchange (ETDEWEB)
Reza Shojaei, Mohammad [Shahrood University of Technology, Department of Physics, Shahrood (Iran, Islamic Republic of)
2016-04-15
In this paper, we have calculated the Dirac and Pauli form factors for u and d quark with light front quark model in N{sup 2}LO approximation for MSTW2008 quark function distributions. By using this approximation we found the parameters of Dirac and Pauli form factors, and then we calculated the form factors function as Q{sup 2}. By comparing with experimental data we concluded that F{sub 1}(Q{sup 2}) and F{sub 2}(Q{sup 2}) are in good agreement with the experimental data. (orig.)
The QCD spectrum with three quark flavors
Bernard, C; DeGrand, T A; Datta, S; DeTar, C E; Gottlieb, S; Heller, U M; Orginos, K; Sugar, R; Toussaint, D; Bernard, Claude; Burch, Tom; Grand, Thomas A. De; Datta, Saumen; Tar, Carleton De; Gottlieb, Steven; Heller, Urs M.; Orginos, Kostas; Sugar, Robert; Toussaint, Doug
2001-01-01
We present results from a lattice hadron spectrum calculation using three flavors of dynamical quarks - two light and one strange, and quenched simulations for comparison. These simulations were done using a one-loop Symanzik improved gauge action and an improved Kogut-Susskind quark action. The lattice spacings, and hence also the physical volumes, were tuned to be the same in all the runs to better expose differences due to flavor number. Lattice spacings were tuned using the static quark potential, so as a byproduct we obtain updated results for the effect of sea quarks on the static quark potential. We find indications that the full QCD meson spectrum is in better agreement with experiment than the quenched spectrum. For the 0++ (a0) meson we see a coupling to two pseudoscalar mesons, or a meson decay on the lattice.
A model of quark and lepton mixing
Energy Technology Data Exchange (ETDEWEB)
King, Stephen F. [School of Physics and Astronomy, University of Southampton,Southampton, SO17 1BJ (United Kingdom)
2014-01-22
We propose a model of quark and lepton mixing based on the tetrahedral A{sub 4} family symmetry with quark-lepton unification via the tetra-colour Pati-Salam gauge group SU(4){sub PS}, together with SU(2){sub L}×U(1){sub R}. The “tetra-model” solves many of the flavour puzzles and remarkably gives ten predictions at leading order, including all six PMNS parameters. The Cabibbo angle is approximately given by θ{sub C}≈1/4, due to the tetra-vacuum alignment (1,4,2), providing the Cabibbo connection between quark and lepton mixing. Higher order corrections are responsible for the smaller quark mixing angles and CP violation and provide corrections to the Cabibbo and lepton mixing angles and phases. The tetra-model involves an SO(10)-like pattern of Dirac and heavy right-handed neutrino masses, with the strong up-type quark mass hierarchy cancelling in the see-saw mechanism, leading to a normal hierarchy of neutrino masses with an atmospheric angle in the first octant, θ{sub 23}{sup l}=40{sup ∘}±1{sup ∘}, a solar angle θ{sub 12}{sup l}=34{sup ∘}±1{sup ∘}, a reactor angle θ{sub 13}{sup l}=9.0{sup ∘}±0.5{sup ∘}, depending on the ratio of neutrino masses m{sub 2}/m{sub 3}, and a Dirac CP violating oscillation phase δ{sup l}=260{sup ∘}±5{sup ∘}.
Niggli, Ernst; Egger, Marcel
2002-05-01
Elementary subcellular Ca2+ signals arising from the opening of single ion channels may offer the possibility to examine the stochastic behavior and the microscopic chemical reaction rates of these channel proteins in their natural environment. Such an analysis can yield detailed information about the molecular function that cannot be derived from recordings obtained from an ensemble of channels. In this review, we summarize experimental evidence suggesting that Ca2+ sparks, elementary Ca2+ signaling events of cardiac and skeletal muscle excitation contraction coupling, may be comprised of a number of smaller Ca2+ signaling events, the Ca2+ quarks.
Top quark and neutrino composite Higgs bosons
Energy Technology Data Exchange (ETDEWEB)
Smetana, Adam [Czech Technical University in Prague, Institute of Experimental and Applied Physics, Prague 2 (Czech Republic)
2013-08-15
In the context of top-quark condensation models, the top quark alone is too light to saturate the correct value of the electroweak scale by its condensate. Within the seesaw scenario the neutrinos can have their Dirac masses large enough so that their condensates can provide a significant contribution to the value of the electroweak scale. We address the question of a phenomenological feasibility of the top-quark and neutrino condensation conspiracy against the electroweak symmetry. It is mandatory to reproduce the masses of electroweak gauge bosons, the top-quark mass and the recently observed scalar mass of 125 GeV and to satisfy the upper limits on absolute value of active neutrino masses. To accomplish that we design a reasonably simplified effective model with two composite Higgs doublets. Additionally, we work with a general number N of right-handed neutrino flavor triplets participating on the seesaw mechanism. There are no experimental constraints limiting this number. The upper limit is set by the model itself. Provided that the condensation scale is of order 10{sup 17-18} GeV and the number of right-handed neutrinos is O(100-1000), the model predicts masses of additional Higgs bosons below 250 GeV and a suppression of the top-quark Yukawa coupling to the 125 GeV particle at the {proportional_to}60 % level of the Standard model value. (orig.)
Top quark and neutrino composite Higgs bosons
Smetana, Adam
2013-08-01
In the context of top-quark condensation models, the top quark alone is too light to saturate the correct value of the electroweak scale by its condensate. Within the seesaw scenario the neutrinos can have their Dirac masses large enough so that their condensates can provide a significant contribution to the value of the electroweak scale. We address the question of a phenomenological feasibility of the top-quark and neutrino condensation conspiracy against the electroweak symmetry. It is mandatory to reproduce the masses of electroweak gauge bosons, the top-quark mass and the recently observed scalar mass of 125 GeV and to satisfy the upper limits on absolute value of active neutrino masses. To accomplish that we design a reasonably simplified effective model with two composite Higgs doublets. Additionally, we work with a general number N of right-handed neutrino flavor triplets participating on the seesaw mechanism. There are no experimental constraints limiting this number. The upper limit is set by the model itself. Provided that the condensation scale is of order 1017-18 GeV and the number of right-handed neutrinos is , the model predicts masses of additional Higgs bosons below 250 GeV and a suppression of the top-quark Yukawa coupling to the 125 GeV particle at the ˜60 % level of the Standard model value.
Quark mass effects in quark number susceptibilities
Graf, Thorben
2016-01-01
The quark degrees of freedom of the QGP with special focus on mass effects are investigated. A next-to-leading-order perturbation theory approach with quark mass dependence is applied and compared to lattice QCD results.
Renormalization and asymptotic expansion of Dirac's polarized vacuum
Gravejat, Philippe; Séré, Eric
2010-01-01
We perform rigorously the charge renormalization of the so-called reduced Bogoliubov-Dirac-Fock (rBDF) model. This nonlinear theory, based on the Dirac operator, describes atoms and molecules while taking into account vacuum polarization effects. We consider the total physical density including both the external density of a nucleus and the self-consistent polarization of the Dirac sea, but no `real' electron. We show that it admits an asymptotic expansion to any order in powers of the physical coupling constant $\\alphaph$, provided that the ultraviolet cut-off behaves as $\\Lambda\\sim e^{3\\pi(1-Z_3)/2\\alphaph}\\gg1$. The renormalization parameter $0
Parton densities with the quark linear potential in the statistical approach
Mirjalili, A; Yazdanpanah, M M
2014-01-01
The statistical approach is used to calculate the parton distribution functions (PDFs) of the nucleon. At first it is assumed that the partons are free particles and the light-front kinematic variables are employed to extract the Bjorken $x$-dependence of the PDFs. These PDFs are used to evaluate the combinations of the sea quarks such as $\\bar d-\\bar u$. As our first attempt to improve the result, we make the statistical parameters to depend on $Q^2$, using different values of Gottfried sum rule. The related results are indicating better behavior by accessing to the PDFs while they contain the $Q^2$ dependence parameters. As a further task and in order to have more improvement in the calculations, a linear potential is considered to describe the quark interactions. The solution of the related Dirac equation yields the Airy function and is considered as a wave function in spatial space. Using the fourier transformation the wave functions are obtained in momentum space. Based on the light-front kinematic varia...
Meson and baryon spectrum for QCD with two light dynamical quarks
Engel, Georg P; Limmer, Markus; Mohler, Daniel; Schäfer, Andreas
2010-01-01
We present results of meson and baryon spectroscopy using the Chirally Improved Dirac operator on lattices of size 16**3 x 32 with two mass-degenerate light sea quarks. Three ensembles with pion masses of 322(5), 470(4) and 525(7) MeV and lattice spacings close to 0.15 fm are investigated. Results on ground and excited states for several channels are given, including spin two mesons and hadrons with strange valence quarks. The analysis of the states is done with the variational method, including two kinds of Gaussian sources and derivative sources. We obtain several ground states fairly precisely and find radial excitations in various channels. Excited baryon results seem to suffer from finite size effects, in particular at small pion masses. We discuss the possible appearance of scattering states in various channels, considering masses and eigenvectors. Partially quenched results in the scalar channel suggest the presence of a 2-particle state, however, in most channels we cannot identify them.
Dirac's Covariant Constraint Dynamics Applied to the Baryon Spectrum
Whitney, Joshua; Crater, Horace
2010-02-01
A baryon is a hadron containing three quarks in a combination of up, down, strange, charm, or bottom. For prediction of the baryon energy spectrum, a baryon is modeled as a three-body system with the interacting forces coming from a set of two-body potentials that depend on the distance between the quarks, the spin-spin and spin-orbit angular momentum coupling terms, and a tensor term. Techniques and equations are derived from Todorov's work on constraint dynamics and the quasi-potential equation together with Two Body Dirac equations developed by Crater and Van Alstine, and adapted to this specific problem by further use of Sazdjian's N-body constraints dynamics for general confined systems. Baryon spectroscopy results are presented and compared with experiment. Typically, a best fit method is used in the analyses that employ several different algorithms, including a gradient approach, Monte Carlo modeling, and simulated annealing methods. )
Blanchet, Steve
2007-01-01
I present here a concise summary of the preprint arXiv:0707.3024, written in collaboration with A. Anisimov and P. Di Bari. There we discuss leptogenesis when {\\em CP} violation stems exlusively from the Dirac phase in the PMNS mixing matrix. Under this assumption it turns out that the situation is very constrained when a hierarchical heavy right-handed (RH) neutrino spectrum is considered: the allowed regions are small and the final asymmetry depends on the initial conditions. On the other hand, for a quasi-degenerate spectrum of RH neutrinos, the {\\em CP} asymmetry can be enhanced and the situation becomes much more favorable, with no dependence on the initial conditions. Interestingly, in the extreme case of resonant leptogenesis, in order to match the observed baryon asymmetry of the Universe, we obtain a lower bound on \\sin \\q_{13} which depends on the lightest active neutrino mass m_1.
Quark-Quark Forces in Quantum Chromodynamics
Arkhipov, A A
2014-01-01
By single-time reduction technique of Bethe-Salpeter formalism for two-fermion systems analytical expressions for the quasipotential of quark-quark interactions in QCD have been obtained in one-gluon exchange approximation. The influence of infrared singularities of gluon Green`s functions on the character of quark-quark forces in QCD has been investigated. The way the asymptotic freedom manifests itself in terms of two-quark interaction quasipotential in quantum chromodynamics is shown. Consistent relativistic consideration of quark interaction problem by single-time reduction technique in QFT allows one to establish a nontrivial energy dependence of the two-quark interaction quasipotential. As a result of the energy dependence of the interaction quasipotential, the character of the forces changes qualitatively during the transition from the discrete spectrum (the region of the negative values of the binding energy) to the continuous spectrum (that of the positive values of the binding energy): the smooth be...
Black, Kevin; The ATLAS collaboration
2017-01-01
The top quark is the heaviest known fundamental particle. As it is the only quark that decays before it hadronizes, this gives us the unique opportunity to probe the properties of bare quarks at the Large Hadron Collider. This talk will present highlights of a few recent precision measurements by the ATLAS Collaboration of the top quark using 13 TeV and 8 TeV collision data: top-quark pair and single top production cross sections including differential distributions will be presented alongside top quark properties measurements. These measurements, including results using boosted top quarks, probe our understanding of top quark production in the TeV regime. Measurements of the top quark mass and searches for rare top quark decays are also presented.
Aloisi, A M
2016-01-01
In 1931, Dirac advanced a startling prediction about the existence of a new elementary particle, characterized by a magnetic charge of a single polarity: the magnetic monopole. This prediction, that was not based on experimental reasons but on mathematical consistency considerations and the generalization of the formalism of quantum mechanics, illustrates emblematically the Dirac conception of the relationship between physics and mathematics. ----- Nel 1931 Dirac avanz\\`o una sorprendente previsione circa l'esistenza di una nuova particella elementare, caratterizzata da una carica magnetica di un'unica polarit\\`a: il monopolo magnetico. Questa previsione, che non era fondata su ragioni sperimentali ma su considerazioni di consistenza matematica e sulla generalizzazione del formalismo della meccanica quantistica, illustra emblematicamente la concezione di Dirac del rapporto tra fisica e matematica.
Decoherence in the Dirac equation
Meyer, D A
1998-01-01
A Dirac particle is represented by a unitarily evolving state vector in a Hilbert space which factors as $H_{spin} \\otimes H_{position}$. Motivated by the similarity to simple models of decoherence consisting of a two state system coupled to an environment, we investigate the occurence of decoherence in the Dirac equation upon tracing over position. We conclude that the physics of this mathematically exact model for decoherence is closely related to Zitterbewegung.
Quark confinement due to creation of micro AdS black holes in quarkonium model
Taki, Mehran
2016-01-01
We use the solution of the Dirac equation for quarkonium atom in the 4D Anti de sitter (AdS$_{4}$) space to investigate the effect of the large negative cosmological constant on the phenomenon of quark confinement. We do the required calculations in the AdS$_{4}$ space to indicate that large cosmological constant can describe the quark confinement. In fact using the coulomb potential in Dirac equation while we employ the AdS metric will additionally lead us to a linear potential in the quark-antiquark interaction which can be considered to explain the quark confinement. This confining term is arising essentially from the geometrical features of the space. On the other hand the origin of the large cosmological constant can be justified by assuming the appearance of micro black holes in the recent hadronic collision process which is now current, for instance, at the LHC project.
CERN Bulletin
2010-01-01
When a group of physicists entered the Main Auditorium, during the evening of 29 June, they felt they had opened a time portal. Paul Dirac in front of a blackboard showing his formula. ©Sandra Hoogeboom An attentive audience, dressed in early 1900 costumes, were watching a lecture by the elusive Paul Dirac, presenting for the first time his famous formula on the blackboard. Paul Adrien Maurice Dirac (1902-1984) was a British mathematical physicist at Cambridge, and one of the "fathers" of quantum mechanics. When he first wrote it, in 1928, Dirac was not sure what his formula really meant. As demonstrated by Andersson four year later, what Dirac had written on the blackboard was the first definition of a positron, hence he is credited with having anticipated the existence of antimatter. The actor John Kohl performs as Paul Dirac. ©Sandra Hoogeboom What the group of puzzled physicists were really observing when they entered the CERN Auditorium was the shoo...
Hadron Masses and Quark Condensate from Overlap Fermions
Liu, K. F.; Dong, S. J.; Lee, F. X.; Zhang, J. B.
We present results on hadron masses and quark condensate from Neuberger's overlap fermion. The scaling and chiral properties and finite volume effects from this new Dirac operator are studied. We find that the generalized Gell-Mann-Oakes-Renner relation is well satisfied down to the physical u and d quark mass range. We find that in the range of the lattice spacing we consider, the π and ϱ masses at a fixed mπ/ mϱ ratio have weak O( a2) dependence.
Index Theorem and Random Matrix Theory for Improved Staggered Quarks
Energy Technology Data Exchange (ETDEWEB)
Follana, E. [Department of Physics and Astronomy, University of Glasgow (United Kingdom); Hart, A. [School of Physics, University of Edinburgh (United Kingdom); Davies, C.T.H. [Department of Physics and Astronomy, University of Glasgow (United Kingdom)
2006-03-15
We study various improved staggered quark Dirac operators on quenched gluon backgrounds in lattice QCD. We find a clear separation of the spectrum of eigenvalues into high chirality, would-be zero modes and others, in accordance with the Index Theorem. We find the expected clustering of the non-zero modes into quartets as we approach the continuum limit. The predictions of random matrix theory for the epsilon regime are well reproduced. We conclude that improved staggered quarks near the continuum limit respond correctly to QCD topology.
Diquark correlations in baryons on the lattice with overlap quarks
Energy Technology Data Exchange (ETDEWEB)
Babich, R.; Howard, J.; Rebbi, C. [Boston Univ., MA (United States). Dept. of Physics; Garron, N. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Hoelbling, C. [Wuppertal Univ. (Gesamthochschule) (Germany). Fachbereich Physik; Lellouch, L. [CNRS Luminy, Marseille (France). Centre de Physique Theorique]|[Wuppertal Univ. (Gesamthochschule) (Germany). Fachbereich Physik
2007-01-15
We evaluate baryon wave functions in both the Coulomb and Landau gauge in lattice QCD. These are constructed from quark propagators calculated with the overlap Dirac operator on quenched gauge configurations at {beta}=6. By comparing baryon states that differ in their diquark content, we find evidence for enhanced correlation in the scalar diquark channel, as favored by quark models. We also summarize earlier results for diquark masses in the Landau gauge, casting them in a form more easily compared with subsequent studies. (orig.)
Bloch-Zener oscillations across a merging transition of Dirac points.
Lim, Lih-King; Fuchs, Jean-Noël; Montambaux, Gilles
2012-04-27
Bloch oscillations are a powerful tool to investigate spectra with Dirac points. By varying band parameters, Dirac points can be manipulated and merged at a topological transition toward a gapped phase. Under a constant force, a Fermi sea initially in the lower band performs Bloch oscillations and may Zener tunnel to the upper band mostly at the location of the Dirac points. The tunneling probability is computed from the low-energy universal Hamiltonian describing the vicinity of the merging. The agreement with a recent experiment on cold atoms in an optical lattice is very good.
Baryon spectrum analysis using Dirac's covariant constraint dynamics
Whitney, Joshua F.; Crater, Horace W.
2014-01-01
We present a relativistic quark model for the baryons that combines three related relativistic formalisms. The three-body constraint formalism of Sazdjian is used to recast three relativistic two-body equations for the three pairs of interacting quarks into a single relativistically covariant three-body equation for the bound state energies, having a Schrodinger-like structure. The two-body equations are the two-body Dirac equations of constraint dynamics derived by Crater and Van Alstine for combined world vector and scalar interactions providing the necessary spin dependent and spin independent interaction terms. The minimal quasipotential formalism of Todorov is used to provide an invariant framework for the vector and scalar dynamics used in the two-body Dirac equations into which is inserted a local simplified version of the Richardson potential. The spectral results are analyzed and compared to experiment using a best fit method and several different algorithms, including a gradient approach, and a Monte Carlo method.
Dirac spectrum of one-flavor QCD at \\theta=0 and continuity of the chiral condensate
Verbaarschot, J J M
2014-01-01
We derive exact analytical expressions for the spectral density of the Dirac operator at fixed \\theta-angle in the microscopic domain of one-flavor QCD. These results are obtained by performing the sum over topological sectors using novel identities involving sums of products of Bessel functions. Because the fermion determinant is not positive definite for negative quark mass, the usual Banks-Casher relation is not valid and has to be replaced by a different mechanism first observed for QCD at nonzero chemical potential. Using the exact results for the spectral density we explain how this mechanism results in a chiral condensate that remains constant when the quark mass changes sign.
Einstein-Yang-Mills-Dirac systems from the discretized Kaluza-Klein theory
Nguyen, Ai Viet; Nguyen, Suan Han; Wali, Kameshwar C
2016-01-01
A unified theory of the non-Abelian gauge interactions with gravity in the framework of a discretized Kaluaza-Kleine theory is constructed with a modified Dirac operator and wedge product. All the couplings of chiral spinors to the non-Abelian gauge fields emerge naturally as components of the couplings of the chiral spinors to the generalized gravity together with some new interactions. In particular, the currently prevalent gravity-QCD-quark and gravity-electroweak-quark-lepton models are shown to follow as special cases of the general framework.
On the strange quark mass with improved staggered quarks
Hein, J.; Davies, C.; Lepage, G. P.; Mason, Q.; Trottier, H.
2002-01-01
We present results on the sum of the masses of light and strange quark using improved staggered quarks. Our calculation uses 2+1 flavours of dynamical quarks. The effects of the dynamical quarks are clearly visible.
Test for a universal behavior of Dirac eigenvalues in the complex Langevin method
Ichihara, Terukazu; Kashiwa, Kouji
2016-01-01
We apply the complex Langevin (CL) method to a chiral random matrix theory (ChRMT) at non-zero chemical potential and study the nearest neighbor spacing (NNS) distribution of the Dirac eigenvalues. The NNS distribution is extracted using an unfolding procedure for the Dirac eigenvalues obtained in the CL method. For large quark mass, we find that the NNS distribution obeys the Ginibre ensemble as expected. For small quark mass, the NNS distribution follows the Wigner surmise for correct convergence case, while it follows the Ginibre ensemble for wrong convergence case. The Wigner surmise is physically reasonable from the chemical potential independence of the ChRMT. The Ginibre ensemble is known to be favored in a phase quenched QCD at finite chemical potential. Our result suggests a possibility that the originally universal behavior of the NNS distribution is preserved even in the CL method for correct convergence case.
Test for a universal behavior of Dirac eigenvalues in the complex Langevin method
Ichihara, Terukazu; Nagata, Keitaro; Kashiwa, Kouji
2016-05-01
We apply the complex Langevin (CL) method to a chiral random matrix theory (ChRMT) at nonzero chemical potential and study the nearest neighbor spacing (NNS) distribution of the Dirac eigenvalues. The NNS distribution is extracted using an unfolding procedure for the Dirac eigenvalues obtained in the CL method. For large quark mass, we find that the NNS distribution obeys the Ginibre ensemble as expected. For small quark mass, the NNS distribution follows the Wigner surmise for the correct convergence case, while it follows the Ginibre ensemble for the wrong convergence case. The Wigner surmise is physically reasonable from the chemical potential independence of the ChRMT. The Ginibre ensemble is known to be favored in a phase-quenched QCD at finite chemical potential. Our result suggests a possibility that the originally universal behavior of the NNS distribution is preserved even in the CL method for the correct convergence case.
Quark confinement in a constituent quark model
Energy Technology Data Exchange (ETDEWEB)
Langfeld, K.; Rho, M. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Service de Physique Theorique
1995-07-01
On the level of an effective quark theory, we define confinement by the absence of quark anti-quark thresholds in correlation function. We then propose a confining Nambu-Jona-Lasinio-type model. The confinement is implemented in analogy to Anderson localization in condensed matter systems. We study the model`s phase structure as well as its behavior under extreme conditions, i.e. high temperature and/or high density.
Renormalisation constants of quark bilinears in lattice QCD with four dynamical Wilson quarks
Blossier, B; Carrasco, N; Dimopoulos, P; Du, X; Frezzotti, R; Gimenez, V; Herdoiza, G; Jansen, K; Lubicz, V; Palao, D; Pallante, E; Pene, O; Petrov, K; Reker, S; Rossi, G C; Sanfilippo, F; Scorzato, L; Simula, S; Urbach, C
2011-01-01
We present preliminary results of the non-perturbative computation of the RI-MOM renormalisation constants in a mass-independent scheme for the action with Iwasaki glue and four dynamical Wilson quarks employed by ETMC. Our project requires dedicated gauge ensembles with four degenerate sea quark flavours at three lattice spacings and at several values of the standard and twisted quark mass parameters. The RI-MOM renormalisation constants are obtained from appropriate O(a) improved estimators extrapolated to the chiral limit.
Indian Academy of Sciences (India)
Yuji Takeuchi
2012-10-01
Since the top quark was discovered at Tevatron in 1995, many top quark properties have been measured. However, the top quark is still interesting due to unique features which originate from the extremely heavy mass, and providing various test grounds on the Standard Model as well as searches for a new physics. Though the measurements of the top quark had been performed only at Tevatron so far, LHC is now ready for measurements with more top quarks than Tevatron. In this article, recent measurements of top quark properties from Tevatron (CDF and DØ) as well as LHC (ATLAS and CMS) are presented.
Mapping curved spacetimes into Dirac spinors
Sabín, Carlos
2016-01-01
We show how to transform a Dirac equation in curved spacetime into a Dirac equation in flat spacetime. In particular, we show that any solution of the free massless Dirac equation in a 1+1 dimensional flat spacetime can be transformed via a local phase transformation into a solution of the corresponding Dirac equation in a curved background, where the spacetime metric is encoded into the phase. In this way, the existing quantum simulators of the Dirac equation can naturally incorporate curved spacetimes. As a first example we use our technique to obtain solutions of the Dirac equation in a particular family of interesting spacetimes in 1+1 dimensions.
LHCb: LHCbDirac is a DIRAC extension to support LHCb specific workflows
Stagni, Federico
2012-01-01
We present LHCbDIRAC, an extension of the DIRAC community Grid solution to handle the LHCb specificities. The DIRAC software has been developed for many years within LHCb only. Nowadays it is a generic software, used by many scientific communities worldwide. Each community wanting to take advantage of DIRAC has to develop an extension, containing all the necessary code for handling their specific cases. LHCbDIRAC is an actively developed extension, implementing the LHCb computing model and workflows. LHCbDIRAC extends DIRAC to handle all the distributed computing activities of LHCb. Such activities include real data processing (reconstruction, stripping and streaming), Monte-Carlo simulation and data replication. Other activities are groups and user analysis, data management, resources management and monitoring, data provenance, accounting for user and production jobs. LHCbDIRAC also provides extensions of the DIRAC interfaces, including a secure web client, python APIs and CLIs. While DIRAC and LHCbDIRAC f...
Lepton and Quark Mixing Patterns from Finite Flavor Symmetries
Yao, Chang-Yuan
2015-01-01
We perform a systematical and analytical study of lepton mixing which can be derived from the subgroups of $SU(3)$ under the assumption that neutrinos are Dirac particles. We find that type D groups can predict lepton mixing patterns compatible with the experimental data at $3\\sigma$ level. The lepton mixing matrix turns out to be of the trimaximal form, and the Dirac CP violating phase is trivial. Moreover, we extend the flavor symmetry to the quark sector. The Cabibbo mixing between the first two generations of quarks can be generated by type D groups. Since all the finite subgroups of $U(3)$ which are not the subgroups of $SU(3)$ have not been classified, an exhaustive scan over all finite discrete groups up to order 2000 is performed with the help of the computer algebra system \\texttt{GAP}. We find that only 90 (10) groups for Dirac (Majorana) neutrinos can generate the lepton mixing angles in the experimentally preferred ranges. The lepton mixing matrix is still the trimaximal pattern and the Dirac CP p...
Microscopic correlations for non-Hermitian Dirac operators in three-dimensional QCD
Akemann, G.
2001-12-01
In the presence of a nonvanishing chemical potential the eigenvalues of the Dirac operator become complex. We calculate spectral correlation functions of complex eigenvalues using a random matrix model approach. Our results apply to non-Hermitian Dirac operators in three-dimensional QCD with broken flavor symmetry and in four-dimensional QCD in the bulk of the spectrum. The derivation follows earlier results of Fyodorov, Khoruzhenko, and Sommers for complex spectra exploiting the existence of orthogonal polynomials in the complex plane. Explicit analytic expressions are given for all microscopic k-point correlation functions in the presence of an arbitrary even number of massive quarks, both in the limit of strong and weak non-Hermiticity. In the latter case the parameter governing the non-Hermiticity of the Dirac matrices is identified with the influence of the chemical potential.
Microscopic correlations of non-Hermitian Dirac operators in three-dimensional QCD
Akemann, G
2001-01-01
In the presence of a non-vanishing chemical potential the eigenvalues of the Dirac operator become complex. We calculate spectral correlation functions of complex eigenvalues using a random matrix model approach. Our results apply to non-Hermitian Dirac operators in three-dimensional QCD with broken flavor symmetry and in four-dimensional QCD in the bulk of the spectrum. The derivation follows earlier results of Fyodorov, Khoruzhenko and Sommers for complex spectra exploiting the existence of orthogonal polynomials in the complex plane. Explicit analytic expressions are given for all microscopic k-point correlation functions in the presence of an arbitrary even number of massive quarks, both in the limit of strong and weak non-Hermiticity. In the latter case the parameter governing the non-Hermiticity of the Dirac matrices is identified with the influence of the chemical potential.
Mendy, J E B; Mendy, Jean El Bachir; Govaerts, Jan
2002-01-01
Given the most general Lorentz invariant four-fermion effective interaction possible for two neutrinos and two charged fermions, whether quarks or leptons, all possible 2-to-2 processes involving two neutrinos, whether Dirac or Majorana ones, and two charged fermions are considered. Explicit and convenient expressions are given for the associated differential cross-sections. Such a parametrization should help assess the sensitivity to physics beyond the Standard Model of neutrino beam experiments which are in the design stage at neutrino factories.
Drell-Yan lepton pair production at LHC and TMD quark densities of the proton
Baranov, S P; Zotov, N P
2014-01-01
We use the TMD quark densities of the proton to investigate unpolarized Drell-Yan lepton pair production in proton-proton collisions at the LHC energies. We investigate the case where the gluon-to-quark splitting occurs at the last evolution step and calculate the TMD sea quark density as a convolution of the CCFM-evolved gluon distribution and the TMD gluon-to-quark splitting function which contains all single logarithmic small-x corrections to the sea quark evolution for any order of perturbation theory. Based on the O(alpha) production amplitude of quark-antiquark annihilation calculated according to the reggeized quark approach, we analyze the distributions on the dilepton invariant mass, transverse momentum and rapidity as well as the specific angular correlations between the produced leptons as measured by the CMS, ATLAS and LHCb collaborations. We argue that these measurements impose stringent constraints on the TMD quark distributions of the proton.
DIRAC: a community grid solution
Energy Technology Data Exchange (ETDEWEB)
Tsaregorodtsev, A [Centre de Physique des Particules de Marseille, 163 Av de Luminy Case 902 13288 Marseille (France); Bargiotti, M; Castellani, G; Charpentier, P; Closier, J; Paterson, S; Santinelli, R [CERN CH-1211 Geneve 23 (Switzerland); Brook, N [H. H. Wills Physics Laboratory, Royal Fort, Tyndal Avenue, Bristol BS8 1TL (United Kingdom); Ramo, A C; Diaz, R G [University of Barcelona, Diagonal 647, ES-08028 Barcelona (Spain); Cioffi, C [University of Oxford, 1, Keble Road, Oxford OX1 3NP (United Kingdom); Kuznetsov, G; Nandakumar, R [Rutherford Appleton Laboratory, Chilton, Didcot Oxon. OX11 0QX (United Kingdom); Li, Y Y [University of Cambridge, Wilberforce Road, Cambridge CB3 OWA (United Kingdom); Miguelez, M S [University of Santiago de Compostela, Campus Universitario Sur, ES-15706 Santiago de Compostela (Spain); Jimenez, S G [University Rovira i Virgili, Campus Sescelades, Avinguda dels Paisos Catalans, 26 Tarragona (Spain); Smith, A C, E-mail: atsareg@in2p3.fr
2008-07-15
The DIRAC system was developed in order to provide a complete solution for using the distributed computing resources of the LHCb experiment at CERN for data production and analysis. It allows a concurrent use of over 10K CPUs and 10M file replicas distributed over many tens of sites. The sites can be part of a Computing Grid such as WLCG or standalone computing clusters all integrated in a single management structure. DIRAC is a generic system with the LHCb specific functionality incorporated through a number of plug-in modules. It can be easily adapted to the needs of other communities. Special attention is paid to the resilience of the DIRAC components to allow an efficient use of non-reliable resources. The DIRAC production management components provide a framework for building highly automated data production systems including data distribution and data driven workload scheduling. In this paper we give an overview of the DIRAC system architecture and design choices. We show how different components are put together to compose an integrated data processing system including all the aspects of the LHCb experiment - from the MC production and raw data reconstruction to the final user analysis.
DIRAC: a community grid solution
Tsaregorodtsev, A; Brook, N; Ramo, A C; Castellani, G; Charpentier, P; Cioffi, C; Closier, J; Díaz, R G; Kuznetsov, G; Li, Y Y; Nandakumar, R; Paterson, S; Santinelli, R; Smith, A C; Miguelez, M S; Jimenez, S G
2008-01-01
The DIRAC system was developed in order to provide a complete solution for using the distributed computing resources of the LHCb experiment at CERN for data production and analysis. It allows a concurrent use of over 10K CPUs and 10M file replicas distributed over many tens of sites. The sites can be part of a Computing Grid such as WLCG or standalone computing clusters all integrated in a single management structure. DIRAC is a generic system with the LHCb specific functionality incorporated through a number of plug-in modules. It can be easily adapted to the needs of other communities. Special attention is paid to the resilience of the DIRAC components to allow an efficient use of non-reliable resources. The DIRAC production management components provide a framework for building highly automated data production systems including data distribution and data driven workload scheduling. In this paper we give an overview of the DIRAC system architecture and design choices. We show how different components are pu...
Institute of Scientific and Technical Information of China (English)
ZONG Hong-Shi; WU Xiao-Hua; SUN Wei-Min; ZHAO En-Guang; WANG Fan
2003-01-01
A method for obtaining the smallcurrent quark mass dependence of the dressed quark propagator froman effective quark-quark interaction model is developed. Within this approach the small current quark mass effects ondressed-quark propagator have been studied. A comparison with previous results is given.
Energy Technology Data Exchange (ETDEWEB)
Paschos, E A
1976-01-01
This contribution reviews the evidence accumulated over the past year in favor of quarks and partons. Then it applies the quark ideas in order to interpret the neutrino-induced production of charm and the structure of neutral currents.
Dirac equations in n + 1 dimensions
Energy Technology Data Exchange (ETDEWEB)
Jiang Yu [Departamento de FIsica, Universidad Autonoma Metropolitana-Iztapalapa, Apartado Postal 55-534, 09340 Mexico DF (Mexico)
2005-02-04
The Dirac equation in n + 1 dimensions is derived by a simple algebraic approach. The similarity in the structure of the arbitrary n-dimensional Dirac equations in a central field and their solutions is discussed.
Iorio, Alberto Orso Maria
2016-01-01
Measurements of top quarks from Run-I and Run-II of the LHC are presented. Results on dif- ferential and inclusive top quark production cross sections, measured by the ATLAS, CMS and LHCb experiments, and measurements of top quark properties and mass are reported.
ATLAS collaboration; LHCb collaboration
2016-01-01
Measurements of top quarks from Run-I and Run-II of the LHC are presented. Results on differential and inclusive top quark production cross sections, measured by the ATLAS, CMS and LHCb experiments, and measurements of top quark properties and mass are reported.
Nucleon electromagnetic form factors in a relativistic quark model with chiral symmetry
Energy Technology Data Exchange (ETDEWEB)
Barik, N.; Das, M.
1987-05-01
The nucleon electromagnetic form factors are computed in an independent quark model based on the Dirac equation. Corrections for centre-of-mass motion and pion-cloud effects are incorporated. Results for static quantities are in reasonable agreement with the experimental data.
Presymmetry in the Standard Model with adulterated Dirac neutrinos
Matute, Ernesto A
2015-01-01
Recently we proposed a model for light Dirac neutrinos in which two right-handed (RH) neutrinos per generation are added to the particles of the Standard Model (SM), implemented with the symmetry of fermionic contents. The ordinary one is decoupled via the high scale type-I seesaw mechanism, while the extra pairs off with its left-handed (LH) partner. The symmetry of lepton and quark contents was merely used as a guideline to the choice of parameters because it is not a proper symmetry. Here we argue that the underlying symmetry to take for this correspondence is presymmetry, the hidden electroweak symmetry of the SM extended with RH neutrinos defined by transformations which exchange lepton and quark bare states with the same electroweak charges and no Majorana mass terms in the underlying Lagrangian. It gives a topological character to fractional charges, relates the number of families to the number of quark colors, and now guarantees the great disparity between the couplings of the two RH neutrinos. Thus, ...
A novel quark-field creation operator construction for hadronic physics in lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Michael Peardon, Jozef Dudek, Robert Edwards, Huey-Wen Lin, David Richards, John Bulava, Colin Morningstar, Keisuke Juge
2009-09-01
A new quark-field smearing algorithm is defined which enables efficient calculations of a broad range of hadron correlation functions. The technique applies a low-rank operator to define smooth fields, that are to be used in hadron creation operators. The resulting space of smooth fields is small enough that all elements of the reduced quark propagator can be computed exactly at reasonable computational cost. Correlations between arbitrary sources, including multi-hadron operators can be computed {\\em a posteriori} without requiring new lattice Dirac operator inversions. The method is tested on realistic lattice sizes with light dynamical quarks.
A novel quark-field creation operator construction for hadronic physics in lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Michael Peardon, Jozef Dudek, Robert Edwards, Huey-Wen Lin, David Richards, John Bulava, Colin Morningstar, Keisuke Juge
2009-09-01
A new quark-field smearing algorithm is defined which enables efficient calculations of a broad range of hadron correlation functions. The technique applies a low-rank operator to define smooth fields, that are to be used in hadron creation operators. The resulting space of smooth fields is small enough that all elements of the reduced quark propagator can be computed exactly at reasonable computational cost. Correlations between arbitrary sources, including multi-hadron operators can be computed {\\em a posteriori} without requiring new lattice Dirac operator inversions. The method is tested on realistic lattice sizes with light dynamical quarks.
Moduli Space of Integrable Dirac Structures
Milani, Vida
2009-01-01
In this paper we introduce the notion of integrable Dirac structures on Hermitian modules. The moduli space of the space of integrable Dirac structures is studied. Then a necessary and sufficient condition for the integrability of a Dirac structure is obtained as the solution of a certain partial differential equation.
Nucleon form factors, generalized parton distributions and quark angular momentum
Energy Technology Data Exchange (ETDEWEB)
Diehl, Markus [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Kroll, Peter [Bergische Univ., Wuppertal (Germany). Fachbereich Physik; Regensburg Univ. (Germany). Institut fuer Theoretische Physik
2013-02-15
We extract the individual contributions from u and d quarks to the Dirac and Pauli form factors of the proton, after a critical examination of the available measurements of electromagnetic nucleon form factors. From this data we determine generalized parton distributions for valence quarks, assuming a particular form for their functional dependence. The result allows us to study various aspects of nucleon structure in the valence region. In particular, we evaluate Ji's sum rule and estimate the total angular momentum carried by valence quarks at the scale {mu}=2 GeV to be J{sup u}{sub v}=0.230{sup +0.009}{sub -0.024} and J{sup d}{sub v}=-0.004{sup +0.010}{sub -0.016}.
Superconductivity in doped Dirac semimetals
Hashimoto, Tatsuki; Kobayashi, Shingo; Tanaka, Yukio; Sato, Masatoshi
2016-07-01
We theoretically study intrinsic superconductivity in doped Dirac semimetals. Dirac semimetals host bulk Dirac points, which are formed by doubly degenerate bands, so the Hamiltonian is described by a 4 ×4 matrix and six types of k -independent pair potentials are allowed by the Fermi-Dirac statistics. We show that the unique spin-orbit coupling leads to characteristic superconducting gap structures and d vectors on the Fermi surface and the electron-electron interaction between intra and interorbitals gives a novel phase diagram of superconductivity. It is found that when the interorbital attraction is dominant, an unconventional superconducting state with point nodes appears. To verify the experimental signature of possible superconducting states, we calculate the temperature dependence of bulk physical properties such as electronic specific heat and spin susceptibility and surface state. In the unconventional superconducting phase, either dispersive or flat Andreev bound states appear between point nodes, which leads to double peaks or a single peak in the surface density of states, respectively. As a result, possible superconducting states can be distinguished by combining bulk and surface measurements.
Universal Behavior in Dirac Spectra
Verbaarschot, J J M
1997-01-01
In these lectures we review recent results on universal fluctuations of QCD Dirac spectra and applications of Random Matrix Theory (RMT) to QCD. We review general properties of Dirac spectra and discuss the relation between chiral symmetry breaking and correlations of Dirac eigenvalues. In particular, we will focus on the microscopic spectral density density, i.e. the spectral density near zero virtuality on the scale of a typical level spacing. The relation with Leutwyler-Smilga sum-rules will be discussed. The success of applications of RMT to spectra of 'complex' systems leads us to the introduction of a chiral Random Matrix Theory (chRMT) with the global symmetries of the QCD partition function. Our central conjecture is that it decribes correlations of QCD Dirac spectra. We will review recent universality proofs supporting this conjecture. Lattice QCD results for the microscopic spectral density and for correlations in the bulk of the spectrum are shown to be in perfect agreement with chRMT. We close wit...
Institute of Scientific and Technical Information of China (English)
M. Ko(c)ak; B. G(o)nül
2007-01-01
The solutions, in terms of orthogonal polynomials, of Dirac equation with analytically solvable potentials are investigated within a novel formalism by transforming the relativistic equation into a Schr(o)dinger-like one. Earlier results are discussed in a unified framework, and some solutions of a large class of potentials are given.
Patrice Loïez
2002-01-01
Photo 01: The DIRAC upstream vacuum channel placed between the target and the upstream detector region. Both the non-intracting primary proton beam and the seconday particle channel travel inside the shown vacuum channel. Photo 02: The DIRAC upstream detector region consisting of 4 planes of GEM/MSGC; 3 planes of Scintillating Fibres; 4 planes of Ionisation hodospope. The photo shows the cabling of GEM/MSGC (right end) and Scintillating Fibres (left end) detectors. Photo 03: Detailed view of the 4 GEM/MSGC planes. The secondary particle channel and the detectors are tilted by 5.7 degrees with respect to the primary proton beam channel visible on the bottom. Photo 04: View of the downstream part of the double arm DIRAC spectrometer, facing the direction of incoming particles. The Drift Chamber system, the scintillation hodoscopes and the threshold Cherenkov counters are shown in the picture. Photo 05: The DIRAC vacuum region between upstream detectors and the dipole magnet. The shielding around the primary pro...
Torsion Gravity for Dirac Fields
Fabbri, Luca
2016-01-01
In this article we will take into account the most complete back-ground with torsion and curvature, providing the most exhaustive coupling for the Dirac field: we will discuss the integrability of the interaction of the matter field and the reduction of the matter field equations.
A mathematical introduction to Dirac's formalism
van Eijndhoven, SJL
1986-01-01
This monograph contains a functional analytic introduction to Dirac''s formalism. The first part presents some new mathematical notions in the setting of triples of Hilbert spaces, mentioning the concept of Dirac basis. The second part introduces a conceptually new theory of generalized functions, integrating the notions of the first part.The last part of the book is devoted to a mathematical interpretation of the main features of Dirac''s formalism. It involves a pairing between distributional bras and kets, continuum expansions and continuum matrices.
Space-Time Geometry of Quark and Strange Quark Matter
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
We study quark and strange quark matter in the context of general relativity. For this purpose, we solve Einstein's field equations for quark and strange quark matter in spherical symmetric space-times. We analyze strange quark matter for the different equations of state (EOS) in the spherical symmetric space-times, thus we are able to obtain the space-time geometries of quark and strange quark matter. Also, we discuss die features of the obtained solutions. The obtained solutions are consistent with the results of Brookhaven Laboratory, i.e. the quark-gluon plasma has a vanishing shear (i.e. quark-gluon plasma is perfect).
Models for Quarks and Elementary Particles. Part II: What is Mass?
Directory of Open Access Journals (Sweden)
Neumann U. K. W.
2008-04-01
Full Text Available It is extremely productive to give the resultant vector ( EV from the outer vector product (Part I of this article series a physical significance. The EV is assumed as electric flux < with the dimensions [Vm]. Based on Maxwell’s laws this develops into the idea of the magnetic monopole (MMP in each quark. The MMP can be brought in relation with the Dirac monopole. The massless MMP is a productive and important idea on the one hand to recognise what mass is and on the other hand to develop the quark structure of massless photon (-likes from the quark composition of the electron. Based on the experiments by Shapiro it is recognised that the sinusoidal oscillations of the quark can be spiralled in the photons. In an extreme case the spiralling of such a sinusoidal arc produces the geometric locus loop of a quark in a mass-loaded particle.
Models for Quarks and Elementary Particles --- Part II: What is Mass?
Directory of Open Access Journals (Sweden)
Neumann U. K. W.
2008-04-01
Full Text Available It is extremely productive to give the resultant vector (EV from the outer vector product (Part I of this article series a physical significance. The EV is assumed as electric flux with the dimensions [Vm]. Based on Maxwell's laws this develops into the idea of the magnetic monopole (MMP in each quark. The MMP can be brought in relation with the Dirac monopole. The massless MMP is a productive and important idea on the one hand to recognise what mass is and on the other hand to develop the quark structure of massless photon (-likes from the quark composition of the electron. Based on the experiments by Shapiro it is recognised that the sinusoidal oscillations of the quark can be spiralled in the photons. In an extreme case the spiralling of such a sinusoidal arc produces the geometric locus loop of a quark in a mass-loaded particle.
DIRAC pilot framework and the DIRAC Workload Management System
Casajus, Adrian; Graciani, Ricardo; Paterson, Stuart; Tsaregorodtsev, Andrei; LHCb DIRAC Team
2010-04-01
DIRAC, the LHCb community Grid solution, has pioneered the use of pilot jobs in the Grid. Pilot Jobs provide a homogeneous interface to an heterogeneous set of computing resources. At the same time, Pilot Jobs allow to delay the scheduling decision to the last moment, thus taking into account the precise running conditions at the resource and last moment requests to the system. The DIRAC Workload Management System provides one single scheduling mechanism for jobs with very different profiles. To achieve an overall optimisation, it organizes pending jobs in task queues, both for individual users and production activities. Task queues are created with jobs having similar requirements. Following the VO policy a priority is assigned to each task queue. Pilot submission and subsequent job matching are based on these priorities following a statistical approach.
On Scale Determination in Lattice QCD with Dynamical Quarks
De, Asit K; Maiti, Jyotirmoy
2008-01-01
Dependence of a/r_c (inverse Sommer parameter in units of lattice spacing a) on am_q (quark mass in lattice unit) has been observed in all lattice QCD simulations with sea quarks including the ones with improved actions. How much of this dependence is a scaling violation has remained an intriguing question. Our approach has been to investigate the issue with an action with known lattice artifacts, i.e., the standard Wilson quark and gauge action with beta=5.6 and 2 degenerate flavors of sea quarks on 16^3 times 32 lattices. In order to study in detail the sea quark mass dependence, measurements are carried out at eight values of the PCAC quark mass values am_q from about 0.07 to below 0.015. Though scaling violations may indeed be present for relatively large am_q, a consistent scenario at sufficiently small am_q seems to emerge in the mass-independent scheme where for a fixed beta, 1/r_0 and sqrt{sigma} have linear dependence on m_q as physical effects similar to the quark mass dependence of the rho mass. We...
Energy Technology Data Exchange (ETDEWEB)
Ahmadov, A.; Azuelos, G.; Bauer, U.; Belyaev, A.; Berger, E. L.; Sullivan, Z.; Tait, T. M. P.
2000-03-24
The top quark, when it was finally discovered at Fermilab in 1995 completed the three-generation structure of the Standard Model (SM) and opened up the new field of top quark physics. Viewed as just another SM quark, the top quark appears to be a rather uninteresting species. Produced predominantly, in hadron-hadron collisions, through strong interactions, it decays rapidly without forming hadrons, and almost exclusively through the single mode t {r_arrow} Wb. The relevant CKM coupling V{sub tb} is already determined by the (three-generation) unitarity of the CKM matrix. Rare decays and CP violation are unmeasurable small in the SM. Yet the top quark is distinguished by its large mass, about 35 times larger than the mass of the next heavy quark, and intriguingly close to the scale of electroweak (EW) symmetry breaking. This unique property raises a number of interesting questions. Is the top quark mass generated by the Higgs mechanism as the SM predicts and is its mass related to the top-Higgs-Yukawa coupling? Or does it play an even more fundamental role in the EW symmetry breaking mechanism? If there are new particles lighter than the top quark, does the top quark decay into them? Could non-SM physics first manifest itself in non-standard couplings of the top quark which show up as anomalies in top quark production and decays? Top quark physics tries to answer these questions. Several properties of the top quark have already been examined at the Tevatron. These include studies of the kinematical properties of top production, the measurements of the top mass, of the top production cross-section, the reconstruction of t{bar t}pairs in the fully hadronic final states, the study of {tau} decays of the top quark, the reconstruction of hadronic decays of the W boson from top decays, the search for flavor changing neutral current decays, the measurement of the W helicity in top decays, and bounds on t{bar t} spin correlations. Most of these measurements are limited by
Unquenched QCD Dirac operator spectra at nonzero baryon chemical potential
Energy Technology Data Exchange (ETDEWEB)
Akemann, G. [Department of Mathematical Sciences, Brunel University West London, Uxbridge UB8 3PH (United Kingdom); Osborn, J.C. [Physics Department, Boston University, Boston, MA 02215 (United States); Splittorff, K. [Nordita, Blegdamsvej 17, DK-2100, Copenhagen O (Denmark)]. E-mail: split@alf.nbi.dk; Verbaarschot, J.J.M. [Department of Physics and Astronomy, SUNY, Stony Brook, NY 11794 (United States)
2005-04-18
The microscopic spectral density of the QCD Dirac operator at nonzero baryon chemical potential for an arbitrary number of quark flavors was derived recently from a random matrix model with the global symmetries of QCD. In this paper we show that these results and extensions thereof can be obtained from the replica limit of a Toda lattice equation. This naturally leads to a factorized form into bosonic and fermionic QCD-like partition functions. In the microscopic limit these partition functions are given by the static limit of a chiral Lagrangian that follows from the symmetry breaking pattern. In particular, we elucidate the role of the singularity of the bosonic partition function in the orthogonal polynomials approach. A detailed discussion of the spectral density for one and two flavors is given.
Dirac and Pauli form factors from lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Collins, S.; Goeckeler, M. [Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Haegler, P. [Mainz Univ. (Germany). Inst. fuer Kernphysik; Regensburg Univ. (DE). Inst. fuer Theoretische Physik] (and others)
2011-06-15
We present a comprehensive analysis of the electromagnetic form factors of the nucleon from a lattice simulation with two flavors of dynamical O(a)-improved Wilson fermions. A key feature of our calculation is that we make use of an extensive ensemble of lattice gauge field configurations with four different lattice spacings, multiple volumes, and pion masses down to m{sub {pi}}{proportional_to}180 MeV. We find that by employing Kelly-inspired parametrizations for the Q{sup 2}-dependence of the form factors, we are able to obtain stable fits over our complete ensemble. Dirac and Pauli radii and the anomalous magnetic moments of the nucleon are extracted and results at light quark masses provide evidence for chiral non-analytic behavior in these fundamental observables. (orig.)
Surrow, Bernd
2013-01-01
The STAR experiment at the Relativistic Heavy-Ion Collider at Brookhaven National Laboratory is carrying out a spin physics program in high-energy polarized proton collisions at $\\sqrt{s}=200\\,$GeV and $\\sqrt{s}=500\\,$GeV to gain a deeper insight into the spin structure and dynamics of the proton. One of the main objectives of the spin physics program at RHIC is the precise determination of the polarized gluon distribution function. The STAR detector is well suited for the reconstruction of various final states involving jets, $\\pi^{0}$, $\\pi^{\\pm}$, e$^{\\pm}$ and $\\gamma$, which allows to measure several different processes. Recent results suggest a gluon spin contribution to the proton spin at the same level as the quark spin contribution itself. The production of $W$ bosons in polarized p+p collisions at $\\sqrt{s}=500\\,$GeV opens a new era in the study of the spin-flavor structure of the proton. $W^{-(+)}$ bosons are produced in $\\bar{u}+d\\;(\\bar{d}+u)$ collisions and can be detected through their leptonic...
Testa, Massimo
1990-01-01
In the large quark mass limit, an argument which identifies the mass of the heavy-light pseudoscalar or scalar bound state with the renormalized mass of the heavy quark is given. The following equation is discussed: m(sub Q) = m(sub B), where m(sub Q) and m(sub B) are respectively the mass of the heavy quark and the mass of the pseudoscalar bound state.
Gravitational Repulsion and Dirac Antimatter
Kowitt, Mark E.
1996-03-01
Based on an analogy with electron and hole dynamics in semiconductors, Dirac's relativistic electron equation is generalized to include a gravitational interaction using an electromagnetic-type approximation of the gravitational potential. With gravitational and inertial masses decoupled, the equation serves to extend Dirac's deduction of antimatter parameters to include the possibility of gravitational repulsion between matter and antimatter. Consequences for general relativity and related “antigravity” issues are considered, including the nature and gravitational behavior of virtual photons, virtual pairs, and negative-energy particles. Basic cosmological implications of antigravity are explored—in particular, potential contributions to inflation, expansion, and the general absence of detectable antimatter. Experimental and observational tests are noted, and new ones suggested.
A path integral formula for quark condensate states in a modified PQCD
Energy Technology Data Exchange (ETDEWEB)
Cabo Montes de Oca, A. [Perimeter Institute for Theoretical Physics, Waterloo, Ontario (Canada); Instituto de Cibernetica, Matematica y Fisica, Grupo de Fisica Teorica, La Habana (Cuba); Cabo-Bizet, N.G. [Centro de Aplicaciones Tecnologicas y Desarrollo Nuclear (CEADEN), Departamento de Fisica, La Habana (Cuba); Bonn University, Institute of Physics, Bonn (Germany); Cabo-Bizet, A. [Centro de Aplicaciones Tecnologicas y Desarrollo Nuclear (CEADEN), Departamento de Fisica, La Habana (Cuba)
2009-11-15
A modified version of PQCD considered in previous works is investigated here in the case of retaining only the quark condensate. The Green function generating functional is expressed in a form in which Dirac's delta functions are now absent from the free propagators. The new expansion implements the dimensional transmutation effect through a single interaction vertex in addition to the standard ones in massless QCD. The new vertex suggest a way for constructing an alternative to the SM, in which the mass and CKM matrices could be generated by the instability of massless QCD under the production of the top quark and other fermions condensates, in a kind of generalized Nambu-Jona-Lasinio mechanism. The results of a two loop evaluation of the vacuum energy indicate that the quark condensate is dynamically generated. However, the energy as a function of the condensate parameter is again unbounded from below in this approximation. Assuming the existence of a minimum of the vacuum energy at the experimental value of the top quark mass m{sub q} =173 GeV, we evaluate the two particle propagator in the quark-anti-quark channel in zero order in the coupling and a ladder approximation in the condensate vertex. Adopting the notion from the former top quark models in which the Higgs field corresponds to the quark condensate, the results suggest that the Higgs particle could be represented by a meson which might appear at energies around twice the top quark mass. (orig.)
Distributions of Dirac Operator Eigenvalues
Akemann, G
2004-01-01
The distribution of individual Dirac eigenvalues is derived by relating them to the density and higher eigenvalue correlation functions. The relations are general and hold for any gauge theory coupled to fermions under certain conditions which are stated. As a special case, we give examples of the lowest-lying eigenvalue distributions for QCD-like gauge theories without making use of earlier results based on the relation to Random Matrix Theory.
Hydrodynamics of the Dirac spectrum
Energy Technology Data Exchange (ETDEWEB)
Liu, Yizhuang, E-mail: yizhuang.liu@stonybrook.edu [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800 (United States); Warchoł, Piotr, E-mail: piotr.warchol@uj.edu.pl [M. Smoluchowski Institute of Physics, Jagiellonian University, PL-30348 Krakow (Poland); Zahed, Ismail, E-mail: ismail.zahed@stonybrook.edu [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800 (United States)
2016-02-10
We discuss a hydrodynamical description of the eigenvalues of the Dirac spectrum in even dimensions in the vacuum and in the large N (volume) limit. The linearized hydrodynamics supports sound waves. The hydrodynamical relaxation of the eigenvalues is captured by a hydrodynamical (tunneling) minimum configuration which follows from a pertinent form of Euler equation. The relaxation from a phase of unbroken chiral symmetry to a phase of broken chiral symmetry occurs over a time set by the speed of sound.
Dirac neutrinos from flavor symmetry
Aranda, Alfredo; Morisi, S; Peinado, E; Valle, J W F
2013-01-01
We present a model where Majorana neutrino mass terms are forbidden by the flavor symmetry group Delta(27). Neutrinos are Dirac fermions and their masses arise in the same way as that of the charged fermions, due to very small Yukawa couplings. The model fits current neutrino oscillation data and correlates the octant of the atmospheric angle with the magnitude of the lightest neutrino mass, with maximal mixing excluded for any neutrino mass
Parabolic metamaterials and Dirac bridges
Colquitt, D. J.; Movchan, N. V.; Movchan, A. B.
2016-10-01
A new class of multi-scale structures, referred to as `parabolic metamaterials' is introduced and studied in this paper. For an elastic two-dimensional triangular lattice, we identify dynamic regimes, which corresponds to so-called `Dirac Bridges' on the dispersion surfaces. Such regimes lead to a highly localised and focussed unidirectional beam when the lattice is excited. We also show that the flexural rigidities of elastic ligaments are essential in establishing the `parabolic metamaterial' regimes.
Juste, A
2006-01-01
Ten years after its discovery at the Tevatron collider, we still know little about the top quark. Its large mass suggests it may play a key role in the mechanism of Electroweak Symmetry Breaking (EWSB), or open a window of sensitivity to new physics related to EWSB and preferentially coupled to it. To determine whether this is the case, precision measurements of top quark properties are necessary. The high statistics samples being collected by the Tevatron experiments during Run II start to incisively probe the top quark sector. This report summarizes the experimental status of the top quark, focusing in particular on the recent measurements from the Tevatron Run II.
Cuevas Maestro, Javier
2016-01-01
An overview of recent top quark measurements in proton-proton collisions at 7, and 8 TeV in data collected with the CMS and ATLAS experiments at the LHC, using a data sample collected during the years 2011, 2012 is presented. The results include measurements of top-quark pairs spin correlation, the top pair charge asymmetry, the cross section of top-quark pair events produced in association with a W or a Z boson. The mass of the top quark is estimated by different methods. Some results on the same topics are also presented in data collected by the CDF and D0 collaborations at the Tevatron collider.
DIRAC: Secure web user interface
Energy Technology Data Exchange (ETDEWEB)
Casajus Ramo, A [University of Barcelona, Diagonal 647, ES-08028 Barcelona (Spain); Sapunov, M, E-mail: sapunov@in2p3.f [Centre de Physique des Particules de Marseille, 163 Av de Luminy Case 902 13288 Marseille (France)
2010-04-01
Traditionally the interaction between users and the Grid is done with command line tools. However, these tools are difficult to use by non-expert users providing minimal help and generating outputs not always easy to understand especially in case of errors. Graphical User Interfaces are typically limited to providing access to the monitoring or accounting information and concentrate on some particular aspects failing to cover the full spectrum of grid control tasks. To make the Grid more user friendly more complete graphical interfaces are needed. Within the DIRAC project we have attempted to construct a Web based User Interface that provides means not only for monitoring the system behavior but also allows to steer the main user activities on the grid. Using DIRAC's web interface a user can easily track jobs and data. It provides access to job information and allows performing actions on jobs such as killing or deleting. Data managers can define and monitor file transfer activity as well as check requests set by jobs. Production managers can define and follow large data productions and react if necessary by stopping or starting them. The Web Portal is build following all the grid security standards and using modern Web 2.0 technologies which allow to achieve the user experience similar to the desktop applications. Details of the DIRAC Web Portal architecture and User Interface will be presented and discussed.
New quarks: exotic versus strong
Holdom, B.
2011-01-01
The new quarks of a fourth family are being pushed into the strongly interacting regime due to the lower limits on their masses. The theoretical basis and experimental implications of such quarks are compared with exotic quarks.
Dakin, James T.
1974-01-01
Reviews theoretical principles underlying the quark model. Indicates that the agreement with experimental results and the understanding of the quark-quark force are two hurdles for the model to survive in the future. (CC)
Dakin, James T.
1974-01-01
Reviews theoretical principles underlying the quark model. Indicates that the agreement with experimental results and the understanding of the quark-quark force are two hurdles for the model to survive in the future. (CC)
Dirac Spectra of 2-dimensional QCD-like theories
Kieburg, Mario; Zafeiropoulos, Savvas
2014-01-01
We analyze Dirac spectra of two-dimensional QCD like theories both in the continuum and on the lattice and classify them according to random matrix theories sharing the same global symmetries. The classification is different from QCD in four dimensions because the anti-unitary symmetries do not commute with $\\gamma_5$. Therefore in a chiral basis, the number of degrees of freedom per matrix element are not given by the Dyson index. Our predictions are confirmed by Dirac spectra from quenched lattice simulations for QCD with two or three colors with quarks in the fundamental representation as well as in the adjoint representation. The universality class of the spectra depends on the parity of the number of lattice points in each direction. Our results show an agreement with random matrix theory that is qualitatively similar to the agreement found for QCD in four dimensions. We discuss the implications for the Mermin-Wagner-Coleman theorem and put our results in the context of two-dimensional disordered systems...
Double Dirac cones in phononic crystals
Li, Yan
2014-07-07
A double Dirac cone is realized at the center of the Brillouin zone of a two-dimensional phononic crystal (PC) consisting of a triangular array of core-shell-structure cylinders in water. The double Dirac cone is induced by the accidental degeneracy of two double-degenerate Bloch states. Using a perturbation method, we demonstrate that the double Dirac cone is composed of two identical and overlapping Dirac cones whose linear slopes can also be accurately predicted from the method. Because the double Dirac cone occurs at a relatively low frequency, a slab of the PC can be mapped onto a slab of zero refractive index material by using a standard retrieval method. Total transmission without phase change and energy tunneling at the double Dirac point frequency are unambiguously demonstrated by two examples. Potential applications can be expected in diverse fields such as acoustic wave manipulations and energy flow control.
Data Management System of the DIRAC Project
Haen, Christophe; Tsaregorodtsev, Andrei
2015-01-01
The DIRAC Interware provides a development framework and a complete set of components for building distributed computing systems. The DIRAC Data Management System (DMS) offers all the necessary tools to ensure data handling operations for small and large user communities. It supports transparent access to storage resources based on multiple technologies, and is easily expandable. The information on data files and replicas is kept in a File Catalog of which DIRAC offers a powerful and versatile implementation (DFC). Data movement can be performed using third party services including FTS3. Bulk data operations are resilient with respect to failures due to the use of the Request Management System (RMS) that keeps track of ongoing tasks. In this contribution we will present an overview of the DIRAC DMS capabilities and its connection with other DIRAC subsystems such as the Transformation System. The DIRAC DMS is in use by several user communities now. The contribution will present the experience of the LHCb exper...
Topological susceptibility with three flavors of staggered quarks
Aubin, C; Billeter, B; DeTar, C; Gottlieb, S; Gregory, E; Heller, U M; Hetrick, J E; Osborn, J; Sugar, R L; Toussaint, D; Billeter, Brian; Gottlieb, Steven
2005-01-01
As one test of the validity of the staggered-fermion fourth-root determinant trick, we examine the suppression of the topological susceptibility of the QCD vacuum in the limit of small quark mass. The suppression is sensitive to the number of light sea quark flavors. Our study is done in the presence of 2+1 flavors of dynamical quarks in the improved staggered fermion formulation. Variance-reduction techniques provide better control of statistical errors. New results from staggered chiral perturbation theory account for taste-breaking effects in the low-quark mass behavior of the susceptibility, thereby reducing scaling violations from this source. Measurements over a range of quark masses at two lattice spacings permit a rough continuum extrapolation to remove the remaining lattice artifacts. The results are consistent with chiral perturbation theory with the correct flavor counting.
Valence-quark distribution functions in the kaon and pion
Chen, Chen; Roberts, Craig D; Wan, Shaolong; Zong, Hong-Shi
2016-01-01
We describe expressions for pion and kaon dressed-quark distribution functions that incorporate contributions from gluons which bind quarks into these mesons and hence overcome a flaw of the commonly used handbag approximation. The distributions therewith obtained are purely valence in character, ensuring that dressed-quarks carry all a meson's momentum at a characteristic hadronic scale and vanishing as $(1-x)^2$ when Bjorken-$x\\to 1$. Comparing such distributions within the pion and kaon, it is apparent that the size of SU(3)-flavour symmetry breaking in meson parton distribution functions is modulated by the flavour dependence of dynamical chiral symmetry breaking. Corrections to these leading-order formulae may be divided into two classes, responsible for shifting dressed-quark momentum into glue and sea-quarks. Working with available empirical information, we build an algebraic framework that is capable of expressing the principal impact of both classes of corrections. This enables a realistic comparison...
Dirac structures on generalized Riemannian manifolds
Vaisman, Izu
2011-01-01
We characterize the Dirac structures that are parallel with respect to Gualtieri's canonical connection of a generalized Riemannian metric. On the other hand, we discuss Dirac structures that are images of generalized tangent structures. These structures turn out to be Dirac structures that, if seen as Lie algebroids, have a symplectic structure. Particularly, if compatibility with a generalized Riemannian metric is required, the symplectic structure is of the Kaehler type.
Alexandrou, C; Panagopoulos, H; Vicari, E
2000-01-01
We compute the ratio between the scale $\\Lambda_L$ associated with a lattice formulation of QCD using the overlap-Dirac operator, and $\\Lambda_{MS-bar}$. To this end, the one-loop relation between the lattice coupling $g_0$ and the coupling renormalized in the MS-bar scheme is calculated, using the lattice background field technique. We also compute the one-loop renormalization $Z_\\Gamma$ of the two-quark operators $\\bar{\\psi} \\Gamma \\psi$, where $\\Gamma$ denotes a generic Dirac matrix. Furthermore, we study the renormalization of quark bilinears which are more extended and have better chiral properties. Finally, we present improved estimates of $Z_\\Gamma$, coming from cactus resummation and from mean field perturbation theory.
A Short Biography of Paul A. M. Dirac and Historical Development of Dirac Delta Function
Debnath, Lokenath
2013-01-01
This paper deals with a short biography of Paul Dirac, his first celebrated work on quantum mechanics, his first formal systematic use of the Dirac delta function and his famous work on quantum electrodynamics and quantum statistics. Included are his first discovery of the Dirac relativistic wave equation, existence of positron and the intrinsic…
E. Laenen
2011-01-01
The theoretical aspects of a number of top quark properties such as its mass and its couplings are reviewed. Essential aspects in the theoretical description of top quark production, singly, in pairs and in association, as well as its decay related to spin and angular correlations are discussed.
Indian Academy of Sciences (India)
Eric Laenen
2012-10-01
The theoretical aspects of a number of top quark properties such as its mass and its couplings are reviewed. Essential aspects in the theoretical description of top quark production, singly, in pairs and in association, as well as its decay related to spin and angular correlations are discussed.
Light quark correlators in a mixed-action setup
Energy Technology Data Exchange (ETDEWEB)
Bernardoni, Fabio [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Garron, Nicolas [Edinburgh Univ. (United Kingdom). SUPA, School of Physics; Hernandez, Pilar [CSIC-Univ. de Valencia (Spain). Inst. de Fisica Corpuscular; Necco, Silvia [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Pena, Carlos [Univ. Autonoma de Madrid (Spain). Dept. de Fisica Teorica y Inst. de Fisica Teorica UAM/CSIC
2011-11-15
We report our progress in simulating Neuberger valence fermions on N{sub f}=2 Wilson O(a)-improved sea quarks. We compute correlators with valence quark masses both in the p- and in the e-regime, and we match the results with the predictions of the Chiral Effective Theory in the mixed regime. This allows us to extract the Low Energy Couplings (LECs) of the N{sub f}=2 theory and to test the validity of the approach. (orig.)
Light quark correlators in a mixed-action setup
Bernardoni, Fabio; Hernandez, Pilar; Necco, Silvia; Pena, Carlos
2011-01-01
We report our progress in simulating Neuberger valence fermions on N_f=2 Wilson O(a)-improved sea quarks. We compute correlators with valence quark masses both in the p- and in the epsilon-regime, and we match the results with the predictions of the Chiral Effective Theory in the mixed regime. This allows us to extract the Low Energy Couplings (LECs) of the N_f=2 theory and to test the validity of the approach.
Energy Technology Data Exchange (ETDEWEB)
Erbacher, Robin D.; /UC, Davis
2005-10-01
While the top quark was discovered in 1995 at the Fermilab Tevatron, a decade later they still have very little information about the top. As the heaviest particle yet discovered, the top quark is interesting in and of itself, but some speculate that it may play a special role in physics beyond the Standard Model. With Run 2 of the Tevatron well underway, they have the opportunity to study top quark properties with much better sensitivity, and to test whether top quarks behave as predicted by current theories. This article focuses on the basics of top quark physics at the Tevatron, highlighting only a sample of the many recent measurements, as new results are being released monthly, and constantly changing the landscape of our knowledge of top.
Light Quark Mass Effects in Bottom Quark Mass Determinations
Hoang, A. H.
2001-01-01
Recent results for charm quark mass effects in perturbative bottom quark mass determinations from $\\Upsilon$ mesons are reviewed. The connection between the behavior of light quark mass corrections and the infrared sensitivity of some bottom quark mass definitions is examined in some detail.
On Scale Determination in Lattice QCD with Dynamical Quarks
De, A K; Maiti, J
2008-01-01
Dependence of $a/r_c$ (inverse Sommer parameter in units of lattice spacing $a$) on $am_q$ (quark mass in lattice unit) has been observed in all lattice QCD simulations with sea quarks including the ones with improved actions. How much of this dependence is a scaling violation has remained an intriguing question. Our approach has been to investigate the issue with an action with known lattice artifacts, i.e., the standard Wilson quark and gauge action with $\\beta=5.6$ and 2 degenerate flavors of sea quarks on $ 16^3 \\times 32 $ lattices. In order to study in detail the sea quark mass dependence, measurements are carried out at eight values of the Wilson hopping parameter $\\kappa$ in the range 0.156 - 0.158 corresponding to PCAC quark mass values $am_q$ from about 0.07 to below 0.015. We analyze the static potential by fitting to the familiar phenomenological form and extract $a/r_c$. Though scaling violations may indeed be present for relatively large $am_q$, a consistent scenario at sufficiently small $am_q$...
Lattice studies of quark spectra and supersymmetric quantum mechanics
Energy Technology Data Exchange (ETDEWEB)
Schierenberg, Sebastian
2012-06-24
In the first part of this work, we study quark spectra at either non-zero temperature or chemical potential. In the first case, we find a possible explanation for the Anderson localization that is observed in the spectrum. We introduce a random matrix model that has the same localization and shares other important properties of the QCD Dirac operator, too. In the case of a non-vanishing chemical potential, we show that the eigenvalue spacing distributions of the Dirac operator are described by simple random matrix models. In the second part of this work, we study supersymmetry on the lattice. We summarize our progress with the blocking approach and show possible problems. Furthermore, we construct a lattice action which is improved with respect to supersymmetry and study this action numerically.
Fermion unification model based on the intrinsic SU(8 symmetry of a generalized Dirac equation
Directory of Open Access Journals (Sweden)
Eckart eMarsch
2015-10-01
Full Text Available A natural generalization of the original Dirac spinor into a multi-component spinor is achieved, which corresponds to the single lepton and the three quarks of the first family of the standard model of elementary particle physics. Different fermions result from similarity transformations of the Dirac equation, but apparently there can be no more fermions according to the maximal multiplicity revealed in this study. Rotations in the fermion state space are achieved by the unitary generators of the U(1 and the SU(3 groups, corresponding to quantum electrodynamics (QED based on electric charge and chromodynamics (QCD based on colour charge. In addition to hypercharge the dual degree of freedom of hyperspin emerges, which occurs due to the duplicity implied by the two related (Weyl and Dirac representations of the Dirac equation. This yields the SU(2 symmetry of the weak interaction, which can be married to U(1 to generate the unified electroweak interaction as in the standard model. Therefore, the symmetry group encompassing all the three groups mentioned above is SU(8, which can accommodate and unify the observed eight basic stable fermions.
Institute of Scientific and Technical Information of China (English)
LI Chang-Hui; DING Hao-Gang; DAI Jian; SONG Xing-Chang
2001-01-01
Several models in noncommutative geometry (NCG) with mild changes to the standard model are introduced to discuss the neutrino mass problem. We use two constraints, Poincaré duality and gauge anomaly free, to discuss the possibility of containing right-handed neutrinos in them. Our work shows that no model in this paper, with each generation containing a right-handed neutrino, can satisfy these two constraints at the same time. So, to consist with neutrino oscillation experiment results, maybe fundamental changes to the present version of NCG are usually needed to include Dirac massive neutrinos.
Dirac tensor with heavy photon
Energy Technology Data Exchange (ETDEWEB)
Bytev, V.V.; Kuraev, E.A. [Joint Institute of Nuclear Research, Moscow (Russian Federation). Bogoliubov Lab. of Theoretical Physics; Scherbakova, E.S. [Hamburg Univ. (Germany). 1. Inst. fuer Theoretische Physik
2012-01-15
For the large-angles hard photon emission by initial leptons in process of high energy annihilation of e{sup +}e{sup -} {yields} to hadrons the Dirac tensor is obtained, taking into account the lowest order radiative corrections. The case of large-angles emission of two hard photons by initial leptons is considered. This result is being completed by the kinematics case of collinear hard photons emission as well as soft virtual and real photons and can be used for construction of Monte-Carlo generators. (orig.)
Superalgebraic representation of Dirac matrices
Monakhov, V. V.
2016-01-01
We consider a Clifford extension of the Grassmann algebra in which operators are constructed from products of Grassmann variables and derivatives with respect to them. We show that this algebra contains a subalgebra isomorphic to a matrix algebra and that it additionally contains operators of a generalized matrix algebra that mix states with different numbers of Grassmann variables. We show that these operators are extensions of spin-tensors to the case of superspace. We construct a representation of Dirac matrices in the form of operators of a generalized matrix algebra.
Phenomenology of Pseudo Dirac Neutrinos
Joshipura, A S; Joshipura, Anjan S.; Rindani, Saurabh D.
2000-01-01
We formulate general conditions on $3\\times 3$ neutrino mass matrices under which a degenerate pair of neutrinos at a high scale would split at low scale by radiative corrections involving only the standard model fields. This generalizes the original observations of Wolfenstein on pseudo Dirac neutrinos to three generations. A specific model involving partially broken discrete symmetry and solving the solar and atmospheric anomalies is proposed. The symmetry pattern of the model naturally generates two large angles one of which can account for the large angle MSW solution to the solar neutrino problem.
An iterative method to compute the overlap Dirac operator at nonzero chemical potential
Bloch, J; Lang, B; Wettig, T
2007-01-01
The overlap Dirac operator at nonzero quark chemical potential involves the computation of the sign function of a non-Hermitian matrix. In this talk we present an iterative method, first proposed by us in Ref. [1], which allows for an efficient computation of the operator, even on large lattices. The starting point is a Krylov subspace approximation, based on the Arnoldi algorithm, for the evaluation of a generic matrix function. The efficiency of this method is spoiled when the matrix has eigenvalues close to a function discontinuity. To cure this, a small number of critical eigenvectors are added to the Krylov subspace, and two different deflation schemes are proposed in this augmented subspace. The ensuing method is then applied to the sign function of the overlap Dirac operator, for two different lattice sizes. The sign function has a discontinuity along the imaginary axis, and the numerical results show how deflation dramatically improves the efficiency of the method.
A note on Zolotarev optimal rational approximation for the overlap Dirac operator
Chiu, T W; Huang, C H; Huang, T R; Chiu, Ting-Wai; Hsieh, Tung-Han; Huang, Chao-Hsi; Huang, Tsung-Ren
2002-01-01
We discuss the salient features of Zolotarev optimal rational approximation for the inverse square root function, in particular, for its applications in lattice QCD with overlap Dirac quark. The theoretical error bound for the matrix-vector multiplication $ H_w (H_w^2)^{-1/2}Y $ is derived. We check that the error bound is always satisfied amply, for any QCD gauge configurations we have tested. An empirical formula for the error bound is determined, together with its numerical values (by evaluating elliptic functions) listed in Table 2 as well as plotted in Figure 3. Our results suggest that with Zolotarev approximation to $ (H_w^2)^{-1/2} $, one can practically preserve the exact chiral symmetry of the overlap Dirac operator to very high precision, for any gauge configurations on a finite lattice.
Liu, Yizhuang
2015-01-01
We show that the QCD Dirac spectrum at finite chemical potential using a 2-matrix model in the spontaneously broken phase, is amenable to a generic 2-dimensional effective action on a curved eigenvalue manifold. The eigenvalues form a droplet with strong screening and non-linear plasmons. The droplet is threaded by a magnetic vortex which is at the origin of a Berry phase. The adiabatic transport in the droplet maps onto the one in the fractional quantum Hall effect, suggesting that composite fermions at half filling are Dirac particles. We use this observation to argue for two novel anomalous effects in the edge transport of composite fermions, and conversely on a novel contribution to the QCD quark condensate in a rotating frame.
Fritzsch, Harald
1983-01-01
Quark rossi, verdi e blu ; quark dotati di stranezza e di incanto ; quark 'su' e 'giù' : sembra che i fisici delle particelle giochino a confondere la curiosità del profano, con queste denominazioni fantasiose. Che cosa significano ? e, soprattutto, i quark sono i costituenti davvero elementari della materia ?
Dirac-Kahler Theory and Massless Fields
Pletyukhov, V A
2010-01-01
Three massless limits of the Dirac-Kahler theory are considered. It is shown that the Dirac-Kahler equation for massive particles can be represented as a result of the gauge-invariant mixture (topological interaction) of the above massless fields.
HILBERT-DIRAC OPERATORS IN CLIFFORD ANALYSIS
Institute of Scientific and Technical Information of China (English)
F.BRACKX; H.DE SCHEPPER
2005-01-01
Around the central theme of "square root" of the Laplace operator it is shown that the classical Riesz potentials of the first and of the second kind allow for an explicit expression of so-called Hilbert-Dirac convolution operators involving natural and complex powers of the Dirac operator.
On localization of Dirac fermions by disorder
Medvedyeva, Mariya Vyacheslavivna
2011-01-01
This thesis is devoted to the effects of disorder on two-dimensional systems of Dirac fermions. Disorder localizes the usual electron system governed by the Schroedinger equation. The influence of disorder on Dirac fermions is qualitevely different. We concentrate on a random mass term in the Dira
Representation-independent manipulations with Dirac spinors
Pal, P B
2007-01-01
Dirac matrices, also known as gamma matrices, are defined only up to a similarity transformation. Usually, some explicit representation of these matrices is assumed in order to deal with them. In this article, we show how it is possible to proceed without any such assumption. Various important identities involving Dirac matrices and spinors have been derived without assuming any representation at any stage.
Contemplations on Dirac's equation in quaternionic coordinates
Schuricht, Dirk; Greiter, Martin
2004-11-01
A formulation of Dirac's equation using complex-quaternionic coordinates appears to yield an enormous gain in formal elegance, as there is no longer any need to invoke Dirac matrices. This formulation, however, entails several peculiarities, which we investigate and attempt to interpret.
Dirac and Weyl semimetals with holographic interactions
Jacobs, V.P.J.
2015-01-01
Dirac and Weyl semimetals are states of matter exhibiting the relativistic physics of, respectively, the Dirac and Weyl equation in a three-dimensional bulk material. These three-dimensional semimetals have recently been realized experimentally in various crystals. Theoretically, especially the noni
Top quark measurements at ATLAS
Grancagnolo, Sergio; The ATLAS collaboration
2017-01-01
The top quark is the heaviest known fundamental particle. As it is the only quark that decays before it hadronizes, this gives us the unique opportunity to probe the properties of bare quarks at the Large Hadron Collider. This talk will present highlights of a few recent precision measurements by the ATLAS Collaboration of the top quark using 13 TeV and 8 TeV collision data: top-quark pair and single top production cross sections including differential distributions will be presented alongside top quark properties measurements. These measurements, including results using boosted top quarks, probe our understanding of top quark production in the TeV regime. Measurements of the top quark mass and searches for rare top quark decays are also presented.
LHCbDIRAC as Apache Mesos microservices
Couturier, Ben
2016-01-01
The LHCb experiment relies on LHCbDIRAC, an extension of DIRAC, to drive its offline computing. This middleware provides a development framework and a complete set of components for building distributed computing systems. These components are currently installed and ran on virtual machines (VM) or bare metal hardware. Due to the increased load of work, high availability is becoming more and more important for the LHCbDIRAC services, and the current installation model is showing its limitations. Apache Mesos is a cluster manager which aims at abstracting heterogeneous physical resources on which various tasks can be distributed thanks to so called "framework". The Marathon framework is suitable for long running tasks such as the DIRAC services, while the Chronos framework meets the needs of cron-like tasks like the DIRAC agents. A combination of the service discovery tool Consul together with HAProxy allows to expose the running containers to the outside world while hiding their dynamic placements. Such an arc...
Dirac particle in gravitational quantum mechanics
Pedram, Pouria
2011-08-01
In this Letter, we consider the effects of the Generalized (Gravitational) Uncertainty Principle (GUP) on the eigenvalues and the eigenfunctions of the Dirac equation. This form of GUP is consistent with various candidates of quantum gravity such as string theory, loop quantum gravity, doubly special relativity and black hole physics and predicts both a minimum measurable length and a maximum measurable momentum. The modified Hamiltonian contains two additional terms proportional to a( and a( where αi are Dirac matrices and a∼1/MPlc is the GUP parameter. For the case of the Dirac free particle and the Dirac particle in a box, we solve the generalized Dirac equation and find the modified energy eigenvalues and eigenfunctions.
The condensate for two dynamical chirally improved quarks in QCD
Lang, C B; Ortner, W; Majumdar, Pushan; Ortner, Wolfgang
2007-01-01
We compare the eigenvalue spectra of the Dirac operator from a simulation with two mass degenerate dynamical chirally improved fermions with Random Matrix Theory. Comparisons with distribution of k-th eigenvalues (k=1,2,3) in fixed topological sectors (nu=0,1) are carried out using the Kolmogorov-Smirnov test. The eigenvalue distributions are well described by the RMT predictions. The match allows us to read off the quark condensate in the chiral limit directly. Correcting for finite size and renormalization we obtain a mean value of -(276 (11)(16) MeV)**3 in the MS-bar scheme.
Institute of Scientific and Technical Information of China (English)
ZONG Hong-Shi; PING Jia-Lun; SUN Wei-Min; CHANG Chao-Hsi; WANG Fan
2002-01-01
We exhibit a method for obtaining the low chemical potential dependence of the dressed quark propagatorfrom an effective quark-quark interaction model. Within this approach we explore the chemical potential dependenceof the dressed-quark propagator, which provides a means of determining the behavior of the chiral and deconfinementorder parameters. A comparison with the results of previous researches is given.
Energy Technology Data Exchange (ETDEWEB)
Campagne, J.E.
1995-04-01
This work deals with the Dirac or Majorana nature and mass effects on the neutrino behaviour. In the first part of this study are given the Dirac equation properties and the Majorana neutrino definition. As the difference between a Dirac and a Majorana neutrino has only a sense if their masses are not equal to zero, the second part presents a generalization of the Dirac mass term and the different ways to generate a neutrino mass. Several comparisons are made in the third part between quarks and leptons families mixtures which are linked intimately to masses generation. The fourth part gives an example of masses possible values and neutrinos particles mixtures matrix elements predicting. The neutrino electromagnetic and weak interactions are then considered as well as the neutrinos production by the neutral currents. The charged currents are however better to discriminate the Dirac or Majorana nature. The neutrinos propagation in the matter and in the vacuum are analyzed (the case of neutrino oscillations more particularly) under the result of recent experimental observations. At last, are presented the evaluation of neutrino mass (if it exists) through the analysis of double beta decay and the sensibility of future experiments. (O.L.). 164 refs., 73 figs., 20 tabs.
Index Theorem and Random Matrix Theory for Improved Staggered Quarks
Energy Technology Data Exchange (ETDEWEB)
Follana, E. [Department of Physics and Astronomy, University of Glasgow, G12 8QQ Glasgow (United Kingdom)
2005-03-15
We study various improved staggered quark Dirac operators on quenched gluon backgrounds in lattice QCD generated using a Symanzik-improved gluon action. We find a clear separation of the spectrum of eigenvalues into would-be zero modes and others. The number of would-be zero modes depends on the topological charge as expected from the Index Theorem, and their chirality expectation value is large. The remaining modes have low chirality and show clear signs of clustering into quartets and approaching the random matrix theory predictions for all topological charge sectors. We conclude that improvement of the fermionic and gauge actions moves the staggered quarks closer to the continuum limit where they respond correctly to QCD topology.
Overlap Dirac operator at nonzero chemical potential and random matrix theory.
Bloch, Jacques; Wettig, Tilo
2006-07-07
We show how to introduce a quark chemical potential in the overlap Dirac operator. The resulting operator satisfies a Ginsparg-Wilson relation and has exact zero modes. It is no longer gamma5 Hermitian, but its nonreal eigenvalues still occur in pairs. We compute the spectral density of the operator on the lattice and show that, for small eigenvalues, the data agree with analytical predictions of non-Hermitian chiral random matrix theory for both trivial and nontrivial topology. We also explain an observed change in the number of zero modes as a function of chemical potential.
Energy Technology Data Exchange (ETDEWEB)
Parke, S.
1998-01-01
In this presentation I will primarily focus on top quark physics but I will include a discussion of the W-boson mass and the possibility of discovering a light Higgs boson via associated production at the Tevatron.
Guichon, P A M; Thomas, A W
1996-01-01
We describe the development of a theoretical description of the structure of finite nuclei based on a relativistic quark model of the structure of the bound nucleons which interact through the (self-consistent) exchange of scalar and vector mesons.
Indian Academy of Sciences (India)
Narendra Singh
2003-01-01
Assuming a relation between the quark mass matrices of the two sectors a unique solution can be obtained for the CKM ﬂavor mixing matrix. A numerical example is worked out which is in excellent agreement with experimental data.
Searches for new quarks and leptons produced in Z -boson decay
Energy Technology Data Exchange (ETDEWEB)
Abrams, G.S.; Adolphsen, C.E.; Averill, D.; Ballam, J.; Barish, B.C.; Barklow, T.; Barnett, B.A.; Bartelt, J.; Bethke, S.; Blockus, D.; Bonvicini, G.; Boyarski, A.; Brabson, B.; Breakstone, A.; Bulos, F.; Burchat, P.R.; Burke, D.L.; Cence, R.J.; Chapman, J.; Chmeissani, M.; Cords, D.; Coupal, D.P.; Dauncey, P.; DeStaebler, H.C.; Dorfan, D.E.; Dorfan, J.M.; Drewer, D.C.; Elia, R.; Feldman, G.J.; Fernandes, D.; Field, R.C.; Ford, W.T.; Fordham, C.; Frey, R.; Fujino, D.; Gan, K.K.; Gero, E.; Gidal, G. (Lawrence Berkeley Laboratory and Department of Physics University of California, Berkeley, California 94720 (US))
1989-11-27
We have searched for events with new-particle topologies in 390 hadronic {ital Z} decays with the Mark II detector at the SLAC Linear Collider. We place 95%-confidence-level lower limits of 40.7 GeV/{ital c}{sup 2} for the top-quark mass, 42.0 GeV/{ital c}{sup 2} for the mass of a fourth-generation charge {minus}(1/3) quark, and 41.3 GeV/{ital c}{sup 2} for the mass of an unstable Dirac neutral lepton.
DEFF Research Database (Denmark)
Sørensen, Paul Haase; Taylor, John C.
1984-01-01
Processes with coloured particles in the initial state are generally infrared divergent. We investigate the effect of this on processes with colourless particles in the initial state, when the amplitude is near an intermediate quark pole. The result is a characteristic logarithmic depedence...... on the 'binding energy'(even though spectator interactions are taken into account), and the result is gauge-invariant. Summed to all orders the logarithms could perhaps suppress the quark pole....
Magnetotransport properties near the Dirac point of Dirac semimetal Cd3As2 nanowires
Wang, Li-Xian; Wang, Shuo; Li, Jin-Guang; Li, Cai-Zhen; Xu, Jun; Yu, Dapeng; Liao, Zhi-Min
2017-02-01
Three-dimensional (3D) Dirac semimetals are featured by 3D linear energy-momentum dispersion relation, which have been proposed to be a desirable system to study Dirac fermions in 3D space and Weyl fermions in solid-state materials. Significantly, to reveal exotic transport properties of Dirac semimetals, the Fermi level should be close to the Dirac point, around which the linear dispersion is retained. Here we report the magnetotransport properties near the Dirac point in Cd3As2 nanowires, manifesting the evolution of band structure under magnetic field. Ambipolar field effect is observed with the Dirac point at V g = 3.9 V. Under high magnetic field, there is a resistivity dip in transfer curve at the Dirac point, which is caused by the Zeeman splitting enhanced density of state around the Dirac point. Furthermore, the low carrier density in the nanowires makes it feasible to enter into the quantum limit regime, resulting in the quantum linear magnetoresistance being observed even at room temperature. Besides, the dramatic reduction of bulk conductivity due to the low carrier density, together with a large surface to volume ratio of the nanowire, collectively help to reveal the Shubnikov-de Haas oscillations from the surface states. Our studies on transport properties around the Dirac point therefore provide deep insights into the emerging exotic physics of Dirac and Weyl fermions.
Some Relations for Quark Confinement and Chiral Symmetry Breaking in QCD
Suganuma, Hideo; Redlich, Krzysztof; Sasaki, Chihiro
2016-01-01
We analytically study the relation between quark confinement and spontaneous chiral-symmetry breaking in QCD. In terms of the Dirac eigenmodes, we derive some formulae for the Polyakov loop, its fluctuations, and the string tension from the Wilson loop. We also investigate the Polyakov loop in terms of the eigenmodes of the Wilson, the clover and the domain wall fermion kernels, respectively. For the confinement quantities, the low-lying Dirac/fermion eigenmodes are found to give negligible contribution, while they are essential for chiral symmetry breaking. These relations indicate no direct one-to-one correspondence between confinement and chiral symmetry breaking in QCD, which seems to be natural because confinement is realized independently of the quark mass.
Benoit-Lévy, Aurélien; Chardin, Gabriel
2014-05-01
We study an unconventional cosmology, in which we investigate the consequences that antigravity would pose to cosmology. We present the main characteristics of the Dirac-Milne Universe, a cosmological model where antimatter has a negative active gravitational mass. In this non-standard Universe, separate domains of matter and antimatter coexist at our epoch without annihilation, separated by a gravitationally induced depletion zone. We show that this cosmology does not require a priori the Dark Matter and Dark Energy components of the standard model of cosmology. Additionally, inflation becomes an unnecessary ingredient. Investigating this model, we show that the classical cosmological tests such as primordial nucleosynthesis, Type Ia supernovæ and Cosmic Microwave Background are surprisingly concordant.
Strange quark momentum fraction from overlap fermion
Sun, Mingyang; Liu, Keh-Fei; Gong, Ming
2015-01-01
We present a calculation of $\\langle x \\rangle_s$ for the strange quark in the nucleon. We also report the ratio of the strange $\\langle x \\rangle$ to that of $u/d$ in the disconnected insertion which will be useful in constraining the global fit of parton distribution functions at small $x$. We adopt overlap fermion action on $2 + 1$ flavor domain-wall fermion configurations on the $24^3 \\times 64$ lattice with a light sea quark mass which corresponds to $m_{\\pi}=330$ MeV. Smeared grid $Z_3$ sources are deployed to calculate the nucleon propagator with low-mode substitution. Even-odd grid sources and time-dilution technique with stochastic noises are used to calculate the high mode contribution to the quark loop. Low mode averaging (LMA) for the quark loop is applied to reduce the statistical error of the disconnected insertion calculation. We find the ratio $\\langle x \\rangle_s/\\langle x \\rangle_{u/d}^{\\mathrm{DI}}= 0.78(3)$ in this study.
Quark and lepton mixing as manifestations of violated mirror symmetry
Energy Technology Data Exchange (ETDEWEB)
Dyatlov, I. T., E-mail: dyatlov@thd.pnpi.spb.ru [National Research Center Kurchatov Institute, Petersburg Nuclear Physics Institute (Russian Federation)
2015-06-15
The existence of heavy mirror analogs of ordinary fermions would provide deeper insight into the gedanken paradox appearing in the Standard Model upon direct parity violation and consisting in a physical distinguishability of left- and right-hand coordinate frames. Arguments are presented in support of the statement that such mirror states may also be involved in the formation of observed properties of the system of Standard Model quarks and leptons—that is, their mass spectra and their weak-mixing matrices: (i) In the case of the involvement of mirror generations, the quark mixing matrix assumes the experimentally observed form. It is determined by the constraints imposed by weak SU(2) symmetry and by the quark-mass hierarchy. (ii) Under the same conditions and upon the involvement of mirror particles, the lepton mixing matrix (neutrino mixing) may become drastically different from its quark analog—the Cabibbo-Kobayashi-Maskawa matrix; that is, it may acquire properties suggested by experimental data. This character of mixing is also indicative of an inverse mass spectrum of Standard Model neutrinos and their Dirac (not Majorana) nature.
Krylov subspace methods for the Dirac equation
Beerwerth, Randolf; Bauke, Heiko
2015-03-01
The Lanczos algorithm is evaluated for solving the time-independent as well as the time-dependent Dirac equation with arbitrary electromagnetic fields. We demonstrate that the Lanczos algorithm can yield very precise eigenenergies and allows very precise time propagation of relativistic wave packets. The unboundedness of the Dirac Hamiltonian does not hinder the applicability of the Lanczos algorithm. As the Lanczos algorithm requires only matrix-vector products and inner products, which both can be efficiently parallelized, it is an ideal method for large-scale calculations. The excellent parallelization capabilities are demonstrated by a parallel implementation of the Dirac Lanczos propagator utilizing the Message Passing Interface standard.
Krylov subspace methods for the Dirac equation
Beerwerth, Randolf
2014-01-01
The Lanczos algorithm is evaluated for solving the time-independent as well as the time-dependent Dirac equation with arbitrary electromagnetic fields. We demonstrate that the Lanczos algorithm can yield very precise eigenenergies and allows very precise time propagation of relativistic wave packets. The Dirac Hamiltonian's property of not being bounded does not hinder the applicability of the Lanczos algorithm. As the Lanczos algorithm requires only matrix-vector and inner products, which both can be efficiently parallelized, it is an ideal method for large-scale calculations. The excellent parallelization capabilities are demonstrated by a parallel implementation of the Dirac Lanczos propagator utilizing the Message Passing Interface standard.
Quasi-Dirac neutrinos at the LHC
Anamiati, G; Nardi, E
2016-01-01
Lepton number violation is searched for at the LHC using same-sign leptons plus jets. The standard lore is that the ratio of same-sign lepton to opposite-sign lepton events, $R_{ll}$, is equal to $R_{ll}=1$ ($R_{ll}=0$) for Majorana (Dirac) neutrinos. We argue that for "quasi-Dirac" neutrinos, $R_{ll}$ can have any value between 0 and 1, the precise value being controlled by the mass splitting versus the width of the quasi-Dirac resonances. A measurement of $R_{ll}\
The Dirac Operator over Abelian Finite Groups
Vaz, Jr., Jayme
1997-01-01
In this paper we show how to construct a Dirac operator on a lattice in complete analogy with the continuum. In fact we consider a more general problem, that is, the Dirac operator over an abelian finite group (for which a lattice is a particular example). Our results appear to be in direct connexion with the so called fermion doubling problem. In order to find this Dirac operator we need to introduce an algebraic structure (that generalizes the Clifford algebras) where we have quantities tha...
Instanton-dyon Ensemble with two Dynamical Quarks: the Chiral Symmetry Breaking
Larsen, Rasmus
2015-01-01
This is the second paper of the series aimed at understanding of the ensemble of the instanton-dyons, now with two flavors of light dynamical quarks. The partition function is appended by the fermionic factor, $(det T)^{N_f}$ and Dirac eigenvalue spectra at small values are derived from the numerical simulation of 64 dyons. Those spectra show clear chiral symmetry breaking pattern at high dyon density. Within current accuracy, the confinement and chiral transitions occur at very similar densities.
Running of the coupling and quark mass in SU(2) with two adjoint fermions
Bursa, Francis; Keegan, Liam; Pica, Claudio; Pickup, Thomas
2009-01-01
We simulate SU(2) gauge theory with two massless Dirac fermions in the adjoint representation. We calculate the running of the Schroedinger Functional coupling and the renormalised quark mass over a wide range of length scales. The running of the coupling is consistent with the existence of an infrared fixed point (IRFP), and we find 0.07 < gamma < 0.56 at the IRFP, depending on the value of the critical coupling.
Basic features of the pion valence-quark distribution function
Directory of Open Access Journals (Sweden)
Lei Chang
2014-10-01
Full Text Available The impulse-approximation expression used hitherto to define the pion's valence-quark distribution function is flawed because it omits contributions from the gluons which bind quarks into the pion. A corrected leading-order expression produces the model-independent result that quarks dressed via the rainbow–ladder truncation, or any practical analogue, carry all the pion's light-front momentum at a characteristic hadronic scale. Corrections to the leading contribution may be divided into two classes, responsible for shifting dressed-quark momentum into glue and sea-quarks. Working with available empirical information, we use an algebraic model to express the principal impact of both classes of corrections. This enables a realistic comparison with experiment that allows us to highlight the basic features of the pion's measurable valence-quark distribution, qπ(x; namely, at a characteristic hadronic scale, qπ(x∼(1−x2 for x≳0.85; and the valence-quarks carry approximately two-thirds of the pion's light-front momentum.
Kaon semileptonic decay form factors with HISQ valence quarks
Gamiz, E; Bazavov, A; Bernard, C; Bouchard, C; DeTar, C; Du, D; El-Khadra, A X; Foley, J; Freeland, E D; Gottlieb, Steven; Heller, U M; Kim, J; Kronfeld, A S; Laiho, J; Levkova, L; Mackenzie, P B; Neil, E T; Oktay, M B; Qiu, Si-Wei; Simone, J N; Sugar, R; Toussaint, D; Van de Water, R S; Zhou, R
2012-01-01
We report on the status of our kaon semileptonic form factor calculations using the highly-improved staggered quark (HISQ) formulation to simulate the valence fermions. We present results for the form factor f_+^{K \\pi}(0) on the asqtad N_f=2+1 MILC configurations, discuss the chiral-continuum extrapolation, and give a preliminary estimate of the total error. We also present a more preliminary set of results for the same form factor but with the sea quarks also simulated with the HISQ action; these results include data at the physical light quark masses. The improvements that we expect to achieve with the use of the HISQ configurations and simulations at the physical quark masses are briefly discussed.
Fermi-Bose duality of the Dirac equation and extended real Clifford-Dirac algebra
Directory of Open Access Journals (Sweden)
I.Yu. Krivsky
2010-01-01
Full Text Available We have proved on the basis of the symmetry analysis of the standard Dirac equation with nonzero mass that this equation may describe not only fermions of spin 1/2 but also bosons of spin 1. The new bosonic symmetries of the Dirac equation in both the Foldy-Wouthuysen and the Pauli-Dirac representations are found. Among these symmetries (together with the 32-dimensional pure matrix algebra of invariance the new, physically meaningful, spin 1 Poincare symmetry of equation under consideration is proved. In order to provide the corresponding proofs, a 64-dimensional extended real Clifford-Dirac algebra is put into consideration.
Decay constants $f_B$ and $f_{B_s}$ and quark masses $m_b$ and $m_c$ from HISQ simulations
Komijani, J; Bernard, C; Brambilla, N; Brown, N; DeTar, C; Du, D; El-Khadra, A X; Freeland, E D; Gámiz, E; Gottlieb, Steven; Heller, U M; Kronfeld, A S; Laiho, J; Mackenzie, P B; Monahan, C; Na, Heechang; Neil, E T; Simone, J N; Sugar, R L; Toussaint, D; Vairo, A; Van de Water, R S
2016-01-01
We present a progress report on our calculation of the decay constants $f_B$ and $f_{B_s}$ from lattice-QCD simulations with highly-improved staggered quarks. Simulations are carried out with several heavy valence-quark masses on $(2+1+1)$-flavor ensembles that include charm sea quarks. We include data at six lattice spacings and several light sea-quark masses, including an approximately physical-mass ensemble at all but the smallest lattice spacing, 0.03 fm. This range of parameters provides excellent control of the continuum extrapolation to zero lattice spacing and of heavy-quark discretization errors. Finally, using the heavy-quark effective theory expansion we present a method of extracting from the same correlation functions the charm- and bottom-quark masses as well as some low-energy constants appearing in the heavy-quark expansion.
Decay constants $f_B$ and $f_{B_s}$ and quark masses $m_b$ and $m_c$ from HISQ simulations
Energy Technology Data Exchange (ETDEWEB)
Komijani, J.; et al.
2016-11-22
We present a progress report on our calculation of the decay constants $f_B$ and $f_{B_s}$ from lattice-QCD simulations with highly-improved staggered quarks. Simulations are carried out with several heavy valence-quark masses on $(2+1+1)$-flavor ensembles that include charm sea quarks. We include data at six lattice spacings and several light sea-quark masses, including an approximately physical-mass ensemble at all but the smallest lattice spacing, 0.03 fm. This range of parameters provides excellent control of the continuum extrapolation to zero lattice spacing and of heavy-quark discretization errors. Finally, using the heavy-quark effective theory expansion we present a method of extracting from the same correlation functions the charm- and bottom-quark masses as well as some low-energy constants appearing in the heavy-quark expansion.
The squares of the dirac and spin-dirac operators on a riemann-cartan space(time)
Notte-Cuello, E. A.; Rodrigues, W. A.; Souza, Q. A. G.
2007-08-01
In this paper we introduce the Dirac and spin-Dirac operators associated to a connection on Riemann-Cartan space(time) and standard Dirac and spin-Dirac operators associated with a Levi-Civita connection on a Riemannian (Lorentzian) space(time) and calculate the squares of these operators, which play an important role in several topics of modern mathematics, in particular in the study of the geometry of moduli spaces of a class of black holes, the geometry of NS-5 brane solutions of type II supergravity theories and BPS solitons in some string theories. We obtain a generalized Lichnerowicz formula, decompositions of the Dirac and spin-Dirac operators and their squares in terms of the standard Dirac and spin-Dirac operators and using the fact that spinor fields (sections of a spin-Clifford bundle) have representatives in the Clifford bundle we present also a noticeable relation involving the spin-Dirac and the Dirac operators.
Recursive fragmentation model with quark spin. Application to quark polarimetry
Artru, X
2010-01-01
An elementary recursive model accounting for the quark spin in the fragmentation of a quark into mesons is presented. The quark spin degree of freedom is represented by a two-components spinor. Spin one meson can be included. The model produces Collins effect and jet handedness. The influence of the initial quark polarisation decays exponentially with the rank of the meson, at dierent rates for longitudinal and transverse polarisations
Dirac field in topologically massive gravity
Sert, Özcan; Adak, Muzaffer
2013-01-01
We consider a Dirac field coupled minimally to the Mielke-Baekler model of gravity and investigate cosmological solutions in three dimensions. We arrive at a family of solutions which exists even in the limit of vanishing cosmological constant.
Dirac and Maxwell equations in Split Octonions
Beradze, Revaz
2016-01-01
The split octonionic form of Dirac and Maxwell equations are found. In contrast with the previous attempts these equations are derived from the octonionic analyticity condition and also we use different basis of the 8-dimensional space of split octonions.
Dirac equation on a curved surface
Brandt, F. T.; Sánchez-Monroy, J. A.
2016-09-01
The dynamics of Dirac particles confined to a curved surface is examined employing the thin-layer method. We perform a perturbative expansion to first-order and split the Dirac field into normal and tangential components to the surface. In contrast to the known behavior of second order equations like Schrödinger, Maxwell and Klein-Gordon, we find that there is no geometric potential for the Dirac equation on a surface. This implies that the non-relativistic limit does not commute with the thin-layer method. Although this problem can be overcome when second-order terms are retained in the perturbative expansion, this would preclude the decoupling of the normal and tangential degrees of freedom. Therefore, we propose to introduce a first-order term which rescues the non-relativistic limit and also clarifies the effect of the intrinsic and extrinsic curvatures on the dynamics of the Dirac particles.
Dirac operators on noncommutative curved spacetimes
Schenkel, Alexander
2013-01-01
We study Dirac operators in the framework of twist-deformed noncommutative geometry. The definition of noncommutative Dirac operators is not unique and we focus on three different ones, each generalizing the commutative Dirac operator in a natural way. We show that the three definitions are mutually inequivalent, and that demanding formal self-adjointness with respect to a suitable inner product singles out a preferred choice. A detailed analysis shows that, if the Drinfeld twist contains sufficiently many Killing vector fields, the three operators coincide, which can simplify explicit calculations considerably. We then turn to the construction of quantized Dirac fields on noncommutative curved spacetimes. We show that there exist unique retarded and advanced Green's operators and construct a canonical anti-commutation relation algebra. In the last part we study noncommutative Minkowski and AdS spacetimes as explicit examples.
Lattice simulations with Nf=2 +1 improved Wilson fermions at a fixed strange quark mass
Bali, Gunnar S.; Scholz, Enno E.; Simeth, Jakob; Söldner, Wolfgang; RQCD Collaboration
2016-10-01
The explicit breaking of chiral symmetry of the Wilson fermion action results in additive quark mass renormalization. Moreover, flavor singlet and nonsinglet scalar currents acquire different renormalization constants with respect to continuum regularization schemes. This complicates keeping the renormalized strange quark mass fixed when varying the light quark mass in simulations with Nf=2 +1 sea quark flavors. Here we present and validate our strategy within the CLS (coordinated lattice simulations) effort to achieve this in simulations with nonperturbatively order-a improved Wilson fermions. We also determine various combinations of renormalization constants and improvement coefficients.
Bootstrapping quarks and gluons
Energy Technology Data Exchange (ETDEWEB)
Chew, G.F.
1979-04-01
Dual topological unitarization (DTU) - the approach to S-matrix causality and unitarity through combinatorial topology - is reviewed. Amplitudes associated with triangulated spheres are shown to constitute the core of particle physics. Each sphere is covered by triangulated disc faces corresponding to hadrons. The leading current candidate for the hadron-face triangulation pattern employs 3-triangle basic subdiscs whose orientations correspond to baryon number and topological color. Additional peripheral triangles lie along the hadron-face perimeter. Certain combinations of peripheral triangles with a basic-disc triangle can be identified as quarks, the flavor of a quark corresponding to the orientation of its edges that lie on the hadron-face perimeter. Both baryon number and flavor are additively conserved. Quark helicity, which can be associated with triangle-interior orientation, is not uniformly conserved and interacts with particle momentum, whereas flavor does not. Three different colors attach to the 3 quarks associated with a single basic subdisc, but there is no additive physical conservation law associated with color. There is interplay between color and quark helicity. In hadron faces with more than one basic subdisc, there may occur pairs of adjacent flavorless but colored triangles with net helicity +-1 that are identifiable as gluons. Broken symmetry is an automatic feature of the bootstrap. T, C and P symmetries, as well as up-down flavor symmetry, persist on all orientable surfaces.
Rizzo, T G
1979-01-01
The weak decay of heavy b and t quarks is discussed using the mixing angles obtained in Fritzsch's model (1978). The author finds that the decay b to c dominates over b to u for 7
Quantum game interpretation of Dirac spinor field
Zhi, Haizhao
2011-01-01
This paper introduced the classical prisoner dilemma with the character and structure of quantum prisoner dilemma's strategy space. Associate with the Dirac spinor field, apply the basic quantum game strategy to the translation of the dynamics of Dirac equation. Decompose the real space and time to lattice we found that the basic interaction of spinor could be translated into quantum game theory. At the same time, we gained the new dynamics of quantized spacial evolutionary game.
On the Dirac Monopole Mass Scale
Caruso, Francisco
2013-01-01
It is shown, by a semi-classical argument, that the Dirac charge quantization is still valid in the (classical) Born-Infeld electromagnetic theory. Then it is possible to calculate Dirac's monopole mass in the framework of this theory, which is not possible in Maxwell's theory. The existence of an upper limit for the field intensities in this theory plays an important role in this proof.
Superpersistent Currents in Dirac Fermion Systems
2017-03-06
TITLE AND SUBTITLE Superpersistent Currents in Dirac Fermion Systems 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9550-15-1-0151 5c. PROGRAM ELEMENT...currents in 2D Dirac material systems and pertinent phenomena in the emerging field of relativistic quantum nonlinear dynamics and chaos. Systematic...anomalous optical transitions, and spin control in topological insulator quantum dots, (4) the discovery of nonlinear dynamics induced anomalous Hall
Klein-Gordon and Dirac gyroscopes
Energy Technology Data Exchange (ETDEWEB)
SadurnI, E [Instituto de Ciencias Fisicas, Universidad Nacional Autonoma de Mexico, Cuernavaca, Morelos (Mexico)], E-mail: sadurni@fis.unam.mx
2009-01-09
The formulation of a rigid body in relativistic quantum mechanics is studied. Departing from an alternate approach at the relativistic classical level, the corresponding Klein-Gordon and Dirac operators for the rigid body are obtained in covariant form. The resulting wave equations are shown to be consistent, by construction, with earlier definitions of a relativistic rigid body by Aldinger et al (1983 Phys. Rev. D 28 3020). Wavefunctions and spectra for both cases are obtained explicitly, including the Dirac gyroscope with asymmetries.
Plexciton dirac points and topological modes
Onbaşlı, Mehmet Cengiz; Yuen-Zhou, Joel; K. Saikin, Semion; Zhu, Tony; Ross, Caroline A.; Bulovic, Vladimir; Baldo, Marc A.
2016-01-01
Plexcitons are polaritonic modes that result from the strong coupling between excitons and plasmons. Here, we consider plexcitons emerging from the interaction of excitons in an organic molecular layer with surface plasmons in a metallic film. We predict the emergence of Dirac cones in the two-dimensional band-structure of plexcitons due to the inherent alignment of the excitonic transitions in the organic layer. An external magnetic field opens a gap between the Dirac cones if the plexciton ...
The Quark's Model and Confinement
Novozhilov, Yuri V.
1977-01-01
Quarks are elementary particles considered to be components of the proton, the neutron, and others. This article presents the quark model as a mathematical concept. Also discussed are gluons and bag models. A bibliography is included. (MA)
The Quark's Model and Confinement
Novozhilov, Yuri V.
1977-01-01
Quarks are elementary particles considered to be components of the proton, the neutron, and others. This article presents the quark model as a mathematical concept. Also discussed are gluons and bag models. A bibliography is included. (MA)
Quark structure of chiral solitons
Diakonov, D
2004-01-01
There is a prejudice that the chiral soliton model of baryons is something orthogonal to the good old constituent quark models. In fact, it is the opposite: the spontaneous chiral symmetry breaking in strong interactions explains the appearance of massive constituent quarks of small size thus justifying the constituent quark models, in the first place. Chiral symmetry ensures that constituent quarks interact very strongly with the pseudoscalar fields. The ``chiral soliton'' is another word for the chiral field binding constituent quarks. We show how the old SU(6) quark wave functions follow from the ``soliton'', however, with computable relativistic corrections and additional quark-antiquark pairs. We also find the 5-quark wave function of the exotic baryon Theta+.
Phenomenology of Dirac Neutralino Dark Matter
Energy Technology Data Exchange (ETDEWEB)
Buckley, Matthew R.; Hooper, Dan; Kumar, Jason
2013-09-01
In supersymmetric models with an unbroken R-symmetry (rather than only R-parity), the neutralinos are Dirac fermions rather than Majorana. In this article, we discuss the phenomenology of neutralino dark matter in such models, including the calculation of the thermal relic abundance, and constraints and prospects for direct and indirect searches. Due to the large elastic scattering cross sections with nuclei predicted in R-symmetric models, we are forced to consider a neutralino that is predominantly bino, with very little higgsino mixing. We find a large region of parameter space in which bino-like Dirac neutralinos with masses between 10 and 380 GeV can annihilate through slepton exchange to provide a thermal relic abundance in agreement with the observed cosmological density, without relying on coannihilations or resonant annihilations. The signatures for the indirect detection of Dirac neutralinos are very different than predicted in the Majorana case, with annihilations proceeding dominately to $\\tau^+ \\tau^-$, $\\mu^+ \\mu^-$ and $e^+ e^-$ final states, without the standard chirality suppression. And unlike Majorana dark matter candidates, Dirac neutralinos experience spin-independent scattering with nuclei through vector couplings (via $Z$ and squark exchange), leading to potentially large rates at direct detection experiments. These and other characteristics make Dirac neutralinos potentially interesting within the context of recent direct and indirect detection anomalies. We also discuss the case in which the introduction of a small Majorana mass term breaks the $R$-symmetry, splitting the Dirac neutralino into a pair of nearly degenerate Majorana states.
Mathe, Z.; Casajus Ramo, A.; Lazovsky, N.; Stagni, F.
2015-12-01
For many years the DIRAC interware (Distributed Infrastructure with Remote Agent Control) has had a web interface, allowing the users to monitor DIRAC activities and also interact with the system. Since then many new web technologies have emerged, therefore a redesign and a new implementation of the DIRAC Web portal were necessary, taking into account the lessons learnt using the old portal. These new technologies allowed to build a more compact, robust and responsive web interface that enables users to have better control over the whole system while keeping a simple interface. The web framework provides a large set of “applications”, each of which can be used for interacting with various parts of the system. Communities can also create their own set of personalised web applications, and can easily extend already existing ones with a minimal effort. Each user can configure and personalise the view for each application and save it using the DIRAC User Profile service as RESTful state provider, instead of using cookies. The owner of a view can share it with other users or within a user community. Compatibility between different browsers is assured, as well as with mobile versions. In this paper, we present the new DIRAC Web framework as well as the LHCb extension of the DIRAC Web portal.
Mulders, Martijn
2016-01-01
Ever since the discovery of the top quark at the Tevatron collider in 1995 the measurement of its mass has been a high priority. As one of the fundamental parameters of the Standard Theory of particle physics, the precise value of the top quark mass together with other inputs provides a test for the self-consistency of the theory, and has consequences for the stability of the Higgs field that permeates the Universe. In this review I will briefly summarize the experimental techniques used at the Tevatron and the LHC experiments throughout the years to measure the top quark mass with ever improving accuracy, and highlight the recent progress in combining all measurements in a single world average combination. As experimental measurements became more precise, the question of their theoretical interpretation has become important. The difficulty of relating the measured quantity to the fundamental top mass parameter has inspired alternative measurement methods that extract the top mass in complementary ways. I wil...
Valence-quark distribution functions in the kaon and pion
Chen, Chen; Chang, Lei; Roberts, Craig D.; Wan, Shaolong; Zong, Hong-Shi
2016-04-01
We describe expressions for pion and kaon dressed-quark distribution functions that incorporate contributions from gluons which bind quarks into these mesons and hence overcome a flaw of the commonly used handbag approximation. The distributions therewith obtained are purely valence in character, ensuring that dressed quarks carry all the meson's momentum at a characteristic hadronic scale and vanish as (1 -x )2 when Bjorken-x →1 . Comparing such distributions within the pion and kaon, it is apparent that the size of S U (3 ) -flavor symmetry breaking in meson parton distribution functions is modulated by the flavor dependence of dynamical chiral symmetry breaking. Corrections to these leading-order formulas may be divided into two classes, responsible for shifting dressed-quark momentum into glue and sea quarks. Working with available empirical information, we build an algebraic framework that is capable of expressing the principal impact of both classes of corrections. This enables a realistic comparison with experiment which allows us to identify and highlight basic features of measurable pion and kaon valence-quark distributions. We find that whereas roughly two thirds of the pion's light-front momentum is carried by valence dressed quarks at a characteristic hadronic scale; this fraction rises to 95% in the kaon; evolving distributions with these features to a scale typical of available Drell-Yan data produces a kaon-to-pion ratio of u -quark distributions that is in agreement with the single existing data set, and predicts a u -quark distribution within the pion that agrees with a modern reappraisal of π N Drell-Yan data. Precise new data are essential in order to validate this reappraisal and because a single modest-quality measurement of the kaon-to-pion ratio cannot be considered definitive.
Valence-quark distribution functions in the kaon and pion
Energy Technology Data Exchange (ETDEWEB)
Chen, Chen; Chang, Lei; Roberts, Craig D.; Wan, Shaolong; Zong, Hong-Shi
2016-04-18
We describe expressions for pion and kaon dressed-quark distribution functions that incorporate contributions from gluons which bind quarks into these mesons and hence overcome a flaw of the commonly used handbag approximation. The distributions therewith obtained are purely valence in character, ensuring that dressed quarks carry all the meson’s momentum at a characteristic hadronic scale and vanish as ( 1 - x ) ^{2} when Bjorken- x → 1 . Comparing such distributions within the pion and kaon, it is apparent that the size of S U ( 3 ) -flavor symmetry breaking in meson parton distribution functions is modulated by the flavor dependence of dynamical chiral symmetry breaking. Corrections to these leading-order formulas may be divided into two classes, responsible for shifting dressed-quark momentum into glue and sea quarks. Working with available empirical information, we build an algebraic framework that is capable of expressing the principal impact of both classes of corrections. This enables a realistic comparison with experiment which allows us to identify and highlight basic features of measurable pion and kaon valence-quark distributions. We find that whereas roughly two thirds of the pion’s light-front momentum is carried by valence dressed quarks at a characteristic hadronic scale; this fraction rises to 95% in the kaon; evolving distributions with these features to a scale typical of available Drell-Yan data produces a kaon-to-pion ratio of u -quark distributions that is in agreement with the single existing data set, and predicts a u -quark distribution within the pion that agrees with a modern reappraisal of π N Drell-Yan data. Precise new data are essential in order to validate this reappraisal and because a single modest-quality measurement of the kaon-to-pion ratio cannot be considered definitive.
From Dirac to neutrino oscillations
Ahrens, Tino
2000-01-01
This text is meant to be a view of the quantum mechanical fonnalism as it develops with the successive introduction of different types oftransfonnations. In particular, it is meant to help the readers with three tasks: acquainting themselves with a general and direct approach to the quantum mechanics of spin one-half and spin-one particles, primarily leptons, photons and massive vector bosons, and to some extent quarks; finding out what some of the related areas of current research interest are; and, last and foremost, trying to understand the subject, beginning with and stressing the principles involved. The exposition is based on finite-dimensional representations of the homogeneous Lorentz group, and the subsequent introduction of gauge transformations, of the Abelian and non Abelian varieties. Reference to classical mechanics is avoided. Acting on the simple basis spinors and vectors, Lorentz transfonnations generate wave and field functions. Equations are obtained by the relativistic generalization o...
Indian Academy of Sciences (India)
H Weigel
2003-11-01
In this talk I review studies of hadron properties in bosonized chiral quark models for the quark ﬂavor dynamics. Mesons are constructed from Bethe–Salpeter equations and baryons emerge as chiral solitons. Such models require regularization and I show that the two-fold Pauli–Villars regularization scheme not only fully regularizes the effective action but also leads the scaling laws for structure functions. For the nucleon structure functions the present approach serves to determine the regularization prescription for structure functions whose leading moments are not given by matrix elements of local operators. Some numerical results are presented for the spin structure functions.
Quark Orbital Angular Momentum
Directory of Open Access Journals (Sweden)
Burkardt Matthias
2015-01-01
Full Text Available Definitions of orbital angular momentum based on Wigner distributions are used as a framework to discuss the connection between the Ji definition of the quark orbital angular momentum and that of Jaffe and Manohar. We find that the difference between these two definitions can be interpreted as the change in the quark orbital angular momentum as it leaves the target in a DIS experiment. The mechanism responsible for that change is similar to the mechanism that causes transverse single-spin asymmetries in semi-inclusive deep-inelastic scattering.
Quark Helicity and Transversity Distributions
Hwang, Dae Sung
2016-01-01
The quark transversity distribution inside nucleon is less understood than the quark unpolarized and helicity distributions inside nucleon. In particular, it is important to know clearly why the quark helicity and transversity distributions are different. We investigate the origin of their discrepancy.
Color confinement multi quark resonance
Energy Technology Data Exchange (ETDEWEB)
Wang Fan [Department of Physics, Nanjing University, Joint Center for Particle Nuclear Physics and Cosmology, Nanjing University and Pupil Mountain Observatory, Nanjing, 210008 (China); Ping, J.L. [Department of Physics, Nanjing Normal University, Nanjing, 210097 (China); Pang, H.R. [Department of Physics, Southeast University, Nanjing, 210008 (China); Chen, L.Z. [Department of Physics, Nanjing University, Joint Center for Particle Nuclear Physics and Cosmology, Nanjing University and Pupil Mountain Observatory, Nanjing, 210008 (China)
2007-06-15
A new kind microscopic resonance, the color confinement multi quark resonance is proposed and studied. The quark delocalization color screening model is compared to one of the chiral quark model, the Salamanca model, and a new mechanism of the intermediate range NN interaction, the mutual distortion of interacting nucleons, is checked to be similar to the {sigma} meson exchange.
First-principles study of Dirac and Dirac-like cones in phononic and photonic crystals
Mei, Jun
2012-07-24
By using the k•p method, we propose a first-principles theory to study the linear dispersions in phononic and photonic crystals. The theory reveals that only those linear dispersions created by doubly degenerate states can be described by a reduced Hamiltonian that can be mapped into the Dirac Hamiltonian and possess a Berry phase of -π. Linear dispersions created by triply degenerate states cannot be mapped into the Dirac Hamiltonian and carry no Berry phase, and, therefore should be called Dirac-like cones. Our theory is capable of predicting accurately the linear slopes of Dirac and Dirac-like cones at various symmetry points in a Brillouin zone, independent of frequency and lattice structure. © 2012 American Physical Society.
Lattice QCD with Nf = 2 + 1 + 1 domain-wall quarks
Chen, Yu-Chih; Chiu, Ting-Wai
2017-04-01
We perform hybrid Monte Carlo simulation of (2 + 1 + 1)-flavors lattice QCD with the optimal domain-wall fermion (which has the effective 4D Dirac operator exactly equal to the Zolotarev optimal rational approximation of the overlap Dirac operator). The gauge ensemble is generated on the 323 × 64 lattice with the extent Ns = 16 in the fifth dimension, and with the plaquette gauge action at β = 6 /g2 = 6.20. The lattice spacing (a ≃ 0.063 fm) is determined by the Wilson flow, using the value √{t0} = 0.1416 (8) fm obtained by the MILC Collaboration for the (2 + 1 + 1)-flavors QCD. The masses of s and c quarks are fixed by the masses of the vector mesons ϕ (1020) and J / ψ (3097) respectively; while the mass of the u / d quarks is heavier than their physical values, with the unitary pion mass Mπ ≃ 280 MeV (and Mπ L ≃ 3). We compute the point-to-point quark propagators, and measure the time-correlation functions of meson and baryon interpolators. Our results of the mass spectra of the lowest-lying hadrons containing s and c quarks are in good agreement with the high energy experimental values, together with the predictions of the charmed baryons which have not been observed in experiments.
Lattice QCD with Nf=2+1+1 domain-wall quarks
Directory of Open Access Journals (Sweden)
Yu-Chih Chen
2017-04-01
Full Text Available We perform hybrid Monte Carlo simulation of (2+1+1-flavors lattice QCD with the optimal domain-wall fermion (which has the effective 4D Dirac operator exactly equal to the Zolotarev optimal rational approximation of the overlap Dirac operator. The gauge ensemble is generated on the 323×64 lattice with the extent Ns=16 in the fifth dimension, and with the plaquette gauge action at β=6/g2=6.20. The lattice spacing (a≃0.063 fm is determined by the Wilson flow, using the value t0=0.1416(8 fm obtained by the MILC Collaboration for the (2+1+1-flavors QCD. The masses of s and c quarks are fixed by the masses of the vector mesons ϕ(1020 and J/ψ(3097 respectively; while the mass of the u/d quarks is heavier than their physical values, with the unitary pion mass Mπ≃280 MeV (and MπL≃3. We compute the point-to-point quark propagators, and measure the time-correlation functions of meson and baryon interpolators. Our results of the mass spectra of the lowest-lying hadrons containing s and c quarks are in good agreement with the high energy experimental values, together with the predictions of the charmed baryons which have not been observed in experiments.
Demilly, A; The ATLAS collaboration
2014-01-01
Properties of the top quark are measured with the ATLAS detector using LHC proton-proton collisions data. Measurements of the top-quark mass and polarisation, as well as of the polarization of W bosons in top quark decays to probe the Wtb-vertex are presented. In addition, measurements of the spin correlation between top and anti-top quarks as well as of the top- quark charge asymmetry, which constitute important tests of QCD and are sensitive to new physics, are discussed.
Energy Technology Data Exchange (ETDEWEB)
Maki, Tuula [Univ. of Helsinki (Finland)
2008-03-18
The top quark is the heaviest elementary particle. Its mass is one of the fundamental parameters of the standard model of particle physics, and an important input to precision electroweak tests. This thesis describes three measurements of the top-quark mass in the dilepton decay channel. The dilepton events have two neutrinos in the final state; neutrinos are weakly interacting particles that cannot be detected with a multipurpose experiment. Therefore, the signal of dilepton events consists of a large amount of missing energy and momentum carried off by the neutrinos. The top-quark mass is reconstructed for each event by assuming an additional constraint from a top mass independent distribution. Template distributions are constructed from simulated samples of signal and background events, and parametrized to form continuous probability density functions. The final top-quark mass is derived using a likelihood fit to compare the reconstructed top mass distribution from data to the parametrized templates. One of the analyses uses a novel technique to add top mass information from the observed number of events by including a cross-section-constraint in the likelihood function. All measurements use data samples collected by the CDF II detector.
Mulders, Martijn
2016-10-01
Ever since the discovery of the top quark at the Tevatron collider in 1995 the measurement of its mass has been a high priority. As one of the fundamental parameters of the Standard Theory of particle physics, the precise value of the top quark mass together with other inputs provides a test for the self-consistency of the theory, and has consequences for the stability of the Higgs field that permeates the Universe. In this review I will briefly summarize the experimental techniques used at the Tevatron and the LHC experiments throughout the years to measure the top quark mass with ever improving accuracy, and highlight the recent progress in combining all measurements in a single world average combination. As experimental measurements became more precise, the question of their theoretical interpretation has become important. The difficulty of relating the measured quantity to the fundamental top mass parameter has inspired alternative measurement methods that extract the top mass in complementary ways. I will discuss the status of those techniques and their results, and present a brief outlook of further improvements in the experimental determination of the top quark mass to be expected at the LHC and beyond.
Indian Academy of Sciences (India)
C P Singh
2000-04-01
Recent trends in the research of quark gluon plasma (QGP) are surveyed and the current experimental and theoretical status regarding the properties and signals of QGP is reported. We hope that the experiments commencing at relativistic heavy-ion collider (RHIC) in 2000 will provide a glimpse of the QGP formation.
Pallante, E.; Petronzio, R.
1995-01-01
We construct an effective Lagrangian for low energy hadronic interactions through an infinite expansion in inverse powers of the low energy cutoff Î›Ï‡ of all possible chiral invariant non-renormalizable interactions between quarks and mesons degrees of freedom arising from the bosonization of a gen
Determination of the strange quark density of the proton from ATLAS measurements of the $W \\to l\
Aad, Georges; Abdallah, Jalal; Abdelalim, Ahmed Ali; Abdesselam, Abdelouahab; Abdinov, Ovsat; Abi, Babak; Abolins, Maris; AbouZeid, Ossama; Abramowicz, Halina; Abreu, Henso; Acerbi, Emilio; Acharya, Bobby Samir; Adamczyk, Leszek; Adams, David; Addy, Tetteh; Adelman, Jahred; Aderholz, Michael; Adomeit, Stefanie; Adragna, Paolo; Adye, Tim; Aefsky, Scott; Aguilar-Saavedra, Juan Antonio; Aharrouche, Mohamed; Ahlen, Steven; Ahles, Florian; Ahmad, Ashfaq; Ahsan, Mahsana; Aielli, Giulio; Akdogan, Taylan; Åkesson, Torsten Paul Ake; Akimoto, Ginga; Akimov, Andrei; Akiyama, Kunihiro; Alam, Mohammad; Alam, Muhammad Aftab; Albert, Justin; Albrand, Solveig; Aleksa, Martin; Aleksandrov, Igor; Alessandria, Franco; Alexa, Calin; Alexander, Gideon; Alexandre, Gauthier; Alexopoulos, Theodoros; Alhroob, Muhammad; Aliev, Malik; Alimonti, Gianluca; Alison, John; Aliyev, Magsud; Allbrooke, Benedict; Allport, Phillip; Allwood-Spiers, Sarah; Almond, John; Aloisio, Alberto; Alon, Raz; Alonso, Alejandro; Alvarez Gonzalez, Barbara; Alviggi, Mariagrazia; Amako, Katsuya; Amaral, Pedro; Amelung, Christoph; Ammosov, Vladimir; Amorim, Antonio; Amorós, Gabriel; Amram, Nir; Anastopoulos, Christos; Ancu, Lucian Stefan; Andari, Nansi; Andeen, Timothy; Anders, Christoph Falk; Anders, Gabriel; Anderson, Kelby; Andreazza, Attilio; Andrei, George Victor; Andrieux, Marie-Laure; Anduaga, Xabier; Angerami, Aaron; Anghinolfi, Francis; Anisenkov, Alexey; Anjos, Nuno; Annovi, Alberto; Antonaki, Ariadni; Antonelli, Mario; Antonov, Alexey; Antos, Jaroslav; Anulli, Fabio; Aoun, Sahar; Aperio Bella, Ludovica; Apolle, Rudi; Arabidze, Giorgi; Aracena, Ignacio; Arai, Yasuo; Arce, Ayana; Arfaoui, Samir; Arguin, Jean-Francois; Arik, Engin; Arik, Metin; Armbruster, Aaron James; Arnaez, Olivier; Arnault, Christian; Artamonov, Andrei; Artoni, Giacomo; Arutinov, David; Asai, Shoji; Asfandiyarov, Ruslan; Ask, Stefan; Åsman, Barbro; Asquith, Lily; Assamagan, Ketevi; Astbury, Alan; Astvatsatourov, Anatoli; Aubert, Bernard; Auge, Etienne; Augsten, Kamil; Aurousseau, Mathieu; Avolio, Giuseppe; Avramidou, Rachel Maria; Axen, David; Ay, Cano; Azuelos, Georges; Azuma, Yuya; Baak, Max; Baccaglioni, Giuseppe; Bacci, Cesare; Bach, Andre; Bachacou, Henri; Bachas, Konstantinos; Backes, Moritz; Backhaus, Malte; Badescu, Elisabeta; Bagnaia, Paolo; Bahinipati, Seema; Bai, Yu; Bailey, David; Bain, Travis; Baines, John; Baker, Oliver Keith; Baker, Mark; Baker, Sarah; Banas, Elzbieta; Banerjee, Piyali; Banerjee, Swagato; Banfi, Danilo; Bangert, Andrea Michelle; Bansal, Vikas; Bansil, Hardeep Singh; Barak, Liron; Baranov, Sergei; Barashkou, Andrei; Barbaro Galtieri, Angela; Barber, Tom; Barberio, Elisabetta Luigia; Barberis, Dario; Barbero, Marlon; Bardin, Dmitri; Barillari, Teresa; Barisonzi, Marcello; Barklow, Timothy; Barlow, Nick; Barnett, Bruce; Barnett, Michael; Baroncelli, Antonio; Barone, Gaetano; Barr, Alan; Barreiro, Fernando; Barreiro Guimarães da Costa, João; Barrillon, Pierre; Bartoldus, Rainer; Barton, Adam Edward; Bartsch, Valeria; Bates, Richard; 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Bondarenko, Valery; Bondioli, Mario; Boonekamp, Maarten; Booth, Chris; Bordoni, Stefania; Borer, Claudia; Borisov, Anatoly; Borissov, Guennadi; Borjanovic, Iris; Borri, Marcello; Borroni, Sara; Bortolotto, Valerio; Bos, Kors; Boscherini, Davide; Bosman, Martine; Boterenbrood, Hendrik; Botterill, David; Bouchami, Jihene; Boudreau, Joseph; Bouhova-Thacker, Evelina Vassileva; Boumediene, Djamel Eddine; Bourdarios, Claire; Bousson, Nicolas; Boveia, Antonio; Boyd, James; Boyko, Igor; Bozhko, Nikolay; Bozovic-Jelisavcic, Ivanka; Bracinik, Juraj; Braem, André; Branchini, Paolo; Brandenburg, George; Brandt, Andrew; Brandt, Gerhard; Brandt, Oleg; Bratzler, Uwe; Brau, Benjamin; Brau, James; Braun, Helmut; Brelier, Bertrand; Bremer, Johan; Brenner, Richard; Bressler, Shikma; Britton, Dave; Brochu, Frederic; Brock, Ian; Brock, Raymond; Brodbeck, Timothy; Brodet, Eyal; Broggi, Francesco; Bromberg, Carl; Bronner, Johanna; Brooijmans, Gustaaf; Brooks, William; Brown, Gareth; Brown, Heather; Bruckman de Renstrom, Pawel; Bruncko, Dusan; Bruneliere, Renaud; Brunet, Sylvie; Bruni, Alessia; Bruni, Graziano; Bruschi, Marco; Buanes, Trygve; Buat, Quentin; Bucci, Francesca; Buchanan, James; Buchanan, Norman; Buchholz, Peter; Buckingham, Ryan; Buckley, Andrew; Buda, Stelian Ioan; Budagov, Ioulian; Budick, Burton; Büscher, Volker; Bugge, Lars; Bulekov, Oleg; Bunse, Moritz; Buran, Torleiv; Burckhart, Helfried; Burdin, Sergey; Burgess, Thomas; Burke, Stephen; Busato, Emmanuel; Bussey, Peter; Buszello, Claus-Peter; Butin, François; Butler, Bart; Butler, John; Buttar, Craig; Butterworth, Jonathan; Buttinger, William; Cabrera Urbán, Susana; Caforio, Davide; Cakir, Orhan; Calafiura, Paolo; Calderini, Giovanni; Calfayan, Philippe; Calkins, Robert; Caloba, Luiz; Caloi, Rita; Calvet, David; Calvet, Samuel; Camacho Toro, Reina; Camarri, Paolo; Cambiaghi, Mario; Cameron, David; Caminada, Lea Michaela; Campana, Simone; Campanelli, Mario; Canale, Vincenzo; Canelli, Florencia; Canepa, Anadi; Cantero, Josu; Capasso, Luciano; Capeans Garrido, Maria Del Mar; Caprini, Irinel; Caprini, Mihai; Capriotti, Daniele; Capua, Marcella; Caputo, Regina; Caramarcu, Costin; Cardarelli, Roberto; Carli, Tancredi; Carlino, Gianpaolo; Carminati, Leonardo; Caron, Bryan; Caron, Sascha; Carrillo Montoya, German D; Carter, Antony; Carter, Janet; Carvalho, João; Casadei, Diego; Casado, Maria Pilar; Cascella, Michele; Caso, Carlo; Castaneda Hernandez, Alfredo Martin; Castaneda-Miranda, Elizabeth; Castillo Gimenez, Victoria; Castro, Nuno Filipe; Cataldi, Gabriella; Cataneo, Fernando; Catinaccio, Andrea; Catmore, James; Cattai, Ariella; Cattani, Giordano; Caughron, Seth; Cauz, Diego; Cavalleri, Pietro; Cavalli, Donatella; Cavalli-Sforza, Matteo; Cavasinni, Vincenzo; Ceradini, Filippo; Cerqueira, Augusto Santiago; Cerri, Alessandro; Cerrito, Lucio; Cerutti, Fabio; Cetin, Serkant Ali; Cevenini, Francesco; Chafaq, Aziz; Chakraborty, Dhiman; Chan, Kevin; Chapleau, Bertrand; Chapman, John Derek; Chapman, John Wehrley; Chareyre, Eve; Charlton, Dave; 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Dittus, Fridolin; Djama, Fares; Djobava, Tamar; do Vale, Maria Aline Barros; Do Valle Wemans, André; Doan, Thi Kieu Oanh; Dobbs, Matt; Dobinson, Robert; Dobos, Daniel; Dobson, Ellie; Dodd, Jeremy; Doglioni, Caterina; Doherty, Tom; Doi, Yoshikuni; Dolejsi, Jiri; Dolenc, Irena; Dolezal, Zdenek; Dolgoshein, Boris; Dohmae, Takeshi; Donadelli, Marisilvia; Donega, Mauro; Donini, Julien; Dopke, Jens; Doria, Alessandra; Dos Anjos, Andre; Dosil, Mireia; Dotti, Andrea; Dova, Maria-Teresa; Dowell, John; Doxiadis, Alexander; Doyle, Tony; Drasal, Zbynek; Drees, Jürgen; Dressnandt, Nandor; Drevermann, Hans; Driouichi, Chafik; Dris, Manolis; Dubbert, Jörg; Dube, Sourabh; Duchovni, Ehud; Duckeck, Guenter; Dudarev, Alexey; Dudziak, Fanny; Dührssen, Michael; Duerdoth, Ian; Duflot, Laurent; Dufour, Marc-Andre; Dunford, Monica; Duran Yildiz, Hatice; Duxfield, Robert; Dwuznik, Michal; Dydak, Friedrich; Düren, Michael; Ebenstein, William; Ebke, Johannes; Eckweiler, Sebastian; Edmonds, Keith; Edwards, Clive; Edwards, Nicholas Charles; Ehrenfeld, Wolfgang; Ehrich, Thies; Eifert, Till; Eigen, Gerald; Einsweiler, Kevin; Eisenhandler, Eric; Ekelof, Tord; El Kacimi, Mohamed; Ellert, Mattias; Elles, Sabine; Ellinghaus, Frank; Ellis, Katherine; Ellis, Nicolas; Elmsheuser, Johannes; Elsing, Markus; Emeliyanov, Dmitry; Engelmann, Roderich; Engl, Albert; Epp, Brigitte; Eppig, Andrew; Erdmann, Johannes; Ereditato, Antonio; Eriksson, Daniel; Ernst, Jesse; Ernst, Michael; Ernwein, Jean; Errede, Deborah; Errede, Steven; Ertel, Eugen; Escalier, Marc; Escobar, Carlos; Espinal Curull, Xavier; Esposito, Bellisario; Etienne, Francois; Etienvre, Anne-Isabelle; Etzion, Erez; Evangelakou, Despoina; Evans, Hal; Fabbri, Laura; Fabre, Caroline; Fakhrutdinov, Rinat; Falciano, Speranza; Fang, Yaquan; Fanti, Marcello; Farbin, Amir; Farilla, Addolorata; Farley, Jason; Farooque, Trisha; Farrington, Sinead; Farthouat, Philippe; Fassnacht, Patrick; Fassouliotis, Dimitrios; Fatholahzadeh, Baharak; Favareto, Andrea; Fayard, Louis; Fazio, Salvatore; Febbraro, Renato; Federic, Pavol; Fedin, Oleg; Fedorko, Woiciech; Fehling-Kaschek, Mirjam; Feligioni, Lorenzo; Fellmann, Denis; Feng, Cunfeng; Feng, Eric; Fenyuk, Alexander; Ferencei, Jozef; Ferland, Jonathan; Fernando, Waruna; Ferrag, Samir; Ferrando, James; Ferrara, Valentina; Ferrari, Arnaud; Ferrari, Pamela; Ferrari, Roberto; Ferreira de Lima, Danilo Enoque; Ferrer, Antonio; Ferrer, Maria Lorenza; Ferrere, Didier; Ferretti, Claudio; Ferretto Parodi, Andrea; Fiascaris, Maria; Fiedler, Frank; Filipčič, Andrej; Filippas, Anastasios; Filthaut, Frank; Fincke-Keeler, Margret; Fiolhais, Miguel; Fiorini, Luca; Firan, Ana; Fischer, Gordon; Fischer, Peter; Fisher, Matthew; Flechl, Martin; Fleck, Ivor; Fleckner, Johanna; Fleischmann, Philipp; Fleischmann, Sebastian; Flick, Tobias; Floderus, Anders; Flores Castillo, Luis; Flowerdew, Michael; Fokitis, Manolis; Fonseca Martin, Teresa; Forbush, David Alan; Formica, Andrea; Forti, Alessandra; Fortin, Dominique; Foster, Joe; Fournier, Daniel; Foussat, Arnaud; Fowler, Andrew; Fowler, Ken; Fox, Harald; Francavilla, Paolo; Franchino, Silvia; Francis, David; Frank, Tal; Franklin, Melissa; Franz, Sebastien; Fraternali, Marco; Fratina, Sasa; French, Sky; Friedrich, Felix; Froeschl, Robert; Froidevaux, Daniel; Frost, James; Fukunaga, Chikara; Fullana Torregrosa, Esteban; Fuster, Juan; Gabaldon, Carolina; Gabizon, Ofir; Gadfort, Thomas; Gadomski, Szymon; Gagliardi, Guido; Gagnon, Pauline; Galea, Cristina; Gallas, Elizabeth; Gallo, Valentina Santina; Gallop, Bruce; Gallus, Petr; Gan, KK; Gao, Yongsheng; Gapienko, Vladimir; Gaponenko, Andrei; Garberson, Ford; Garcia-Sciveres, Maurice; García, Carmen; García Navarro, José Enrique; Gardner, Robert; Garelli, Nicoletta; Garitaonandia, Hegoi; Garonne, Vincent; Garvey, John; Gatti, Claudio; Gaudio, Gabriella; Gaur, Bakul; Gauthier, Lea; Gavrilenko, Igor; Gay, Colin; Gaycken, Goetz; Gayde, Jean-Christophe; Gazis, Evangelos; Ge, Peng; Gee, Norman; Geerts, Daniël Alphonsus Adrianus; Geich-Gimbel, Christoph; Gellerstedt, Karl; Gemme, Claudia; Gemmell, Alistair; Genest, Marie-Hélène; Gentile, Simonetta; George, Matthias; George, Simon; Gerlach, Peter; Gershon, Avi; Geweniger, Christoph; Ghazlane, Hamid; Ghodbane, Nabil; Giacobbe, Benedetto; Giagu, Stefano; Giakoumopoulou, Victoria; Giangiobbe, Vincent; Gianotti, Fabiola; Gibbard, Bruce; Gibson, Adam; Gibson, Stephen; Gilbert, Laura; Gilewsky, Valentin; Gillberg, Dag; Gillman, Tony; Gingrich, Douglas; Ginzburg, Jonatan; Giokaris, Nikos; Giordani, MarioPaolo; Giordano, Raffaele; Giorgi, Francesco Michelangelo; Giovannini, Paola; Giraud, Pierre-Francois; Giugni, Danilo; Giunta, Michele; Giusti, Paolo; Gjelsten, Børge Kile; Gladilin, Leonid; Glasman, Claudia; Glatzer, Julian; Glazov, Alexandre; Glitza, Karl-Walter; Glonti, George; Goddard, Jack Robert; Godfrey, Jennifer; Godlewski, Jan; Goebel, Martin; Göpfert, Thomas; Goeringer, Christian; Gössling, Claus; Göttfert, Tobias; Goldfarb, Steven; Golling, Tobias; Gomes, Agostinho; Gomez Fajardo, Luz Stella; Gonçalo, Ricardo; Goncalves Pinto Firmino Da Costa, Joao; Gonella, Laura; Gonidec, Allain; Gonzalez, Saul; González de la Hoz, Santiago; Gonzalez Parra, Garoe; Gonzalez Silva, Laura; Gonzalez-Sevilla, Sergio; Goodson, Jeremiah Jet; Goossens, Luc; Gorbounov, Petr Andreevich; Gordon, Howard; Gorelov, Igor; Gorfine, Grant; Gorini, Benedetto; Gorini, Edoardo; Gorišek, Andrej; Gornicki, Edward; Gorokhov, Serguei; Goryachev, Vladimir; Gosdzik, Bjoern; Gosselink, Martijn; Gostkin, Mikhail Ivanovitch; Gough Eschrich, Ivo; Gouighri, Mohamed; Goujdami, Driss; Goulette, Marc Phillippe; Goussiou, Anna; Goy, Corinne; Gozpinar, Serdar; Grabowska-Bold, Iwona; Grafström, Per; Grahn, Karl-Johan; Grancagnolo, Francesco; Grancagnolo, Sergio; Grassi, Valerio; Gratchev, Vadim; Grau, Nathan; Gray, Heather; Gray, Julia Ann; Graziani, Enrico; Grebenyuk, Oleg; Greenshaw, Timothy; Greenwood, Zeno Dixon; Gregersen, Kristian; Gregor, Ingrid-Maria; Grenier, Philippe; Griffiths, Justin; Grigalashvili, Nugzar; Grillo, Alexander; Grinstein, Sebastian; Grishkevich, Yaroslav; Grivaz, Jean-Francois; Groh, Manfred; Gross, Eilam; Grosse-Knetter, Joern; Groth-Jensen, Jacob; Grybel, Kai; Guarino, Victor; Guest, Daniel; Guicheney, Christophe; Guida, Angelo; Guindon, Stefan; Guler, Hulya; Gunther, Jaroslav; Guo, Bin; Guo, Jun; Gupta, Ambreesh; Gusakov, Yury; Gushchin, Vladimir; Gutierrez, Phillip; Guttman, Nir; Gutzwiller, Olivier; Guyot, Claude; Gwenlan, Claire; Gwilliam, Carl; Haas, Andy; Haas, Stefan; Haber, Carl; Hadavand, Haleh Khani; Hadley, David; Haefner, Petra; Hahn, Ferdinand; Haider, Stefan; Hajduk, Zbigniew; Hakobyan, Hrachya; Hall, David; Haller, Johannes; Hamacher, Klaus; Hamal, Petr; Hamer, Matthias; Hamilton, Andrew; Hamilton, Samuel; Han, Hongguang; Han, Liang; Hanagaki, Kazunori; Hanawa, Keita; Hance, Michael; Handel, Carsten; Hanke, Paul; Hansen, John Renner; Hansen, Jørgen Beck; Hansen, Jorn Dines; Hansen, Peter Henrik; Hansson, Per; Hara, Kazuhiko; Hare, Gabriel; Harenberg, Torsten; Harkusha, Siarhei; Harper, Devin; Harrington, Robert; Harris, Orin; Harrison, Karl; Hartert, Jochen; Hartjes, Fred; Haruyama, Tomiyoshi; Harvey, Alex; Hasegawa, Satoshi; Hasegawa, Yoji; Hassani, Samira; Hatch, Mark; Hauff, Dieter; Haug, Sigve; Hauschild, Michael; Hauser, Reiner; Havranek, Miroslav; Hawes, Brian; Hawkes, Christopher; Hawkings, Richard John; Hawkins, Anthony David; Hawkins, Donovan; Hayakawa, Takashi; Hayashi, Takayasu; Hayden, Daniel; Hayward, Helen; Haywood, Stephen; Hazen, Eric; He, Mao; Head, Simon; Hedberg, Vincent; Heelan, Louise; Heim, Sarah; Heinemann, Beate; Heisterkamp, Simon; Helary, Louis; Heller, Claudio; Heller, Matthieu; Hellman, Sten; Hellmich, Dennis; Helsens, Clement; Henderson, Robert; Henke, Michael; Henrichs, Anna; Henriques Correia, Ana Maria; Henrot-Versille, Sophie; Henry-Couannier, Frédéric; Hensel, Carsten; Henß, Tobias; Hernandez, Carlos Medina; Hernández Jiménez, Yesenia; Herrberg, Ruth; Hershenhorn, Alon David; Herten, Gregor; Hertenberger, Ralf; Hervas, Luis; Hesketh, Gavin Grant; Hessey, Nigel; Higón-Rodriguez, Emilio; Hill, Daniel; Hill, John; Hill, Norman; Hiller, Karl Heinz; Hillert, Sonja; Hillier, Stephen; Hinchliffe, Ian; Hines, Elizabeth; Hirose, Minoru; Hirsch, Florian; Hirschbuehl, Dominic; Hobbs, John; Hod, Noam; Hodgkinson, Mark; Hodgson, Paul; Hoecker, Andreas; Hoeferkamp, Martin; Hoffman, Julia; Hoffmann, Dirk; Hohlfeld, Marc; Holder, Martin; Holmgren, Sven-Olof; Holy, Tomas; Holzbauer, Jenny; Homma, Yasuhiro; Hong, Tae Min; Hooft van Huysduynen, Loek; Horazdovsky, Tomas; Horn, Claus; Horner, Stephan; Hostachy, Jean-Yves; Hou, Suen; Houlden, Michael; Hoummada, Abdeslam; Howarth, James; Howell, David; Hristova, Ivana; Hrivnac, Julius; Hruska, Ivan; Hryn'ova, Tetiana; Hsu, Pai-hsien Jennifer; Hsu, Shih-Chieh; Huang, Guang Shun; Hubacek, Zdenek; Hubaut, Fabrice; Huegging, Fabian; Huettmann, Antje; Huffman, Todd Brian; Hughes, Emlyn; Hughes, Gareth; Hughes-Jones, Richard; Huhtinen, Mika; Hurst, Peter; Hurwitz, Martina; Husemann, Ulrich; Huseynov, Nazim; Huston, Joey; Huth, John; Iacobucci, Giuseppe; Iakovidis, Georgios; Ibbotson, Michael; Ibragimov, Iskander; Ichimiya, Ryo; Iconomidou-Fayard, Lydia; Idarraga, John; Iengo, Paolo; Igonkina, Olga; Ikegami, Yoichi; Ikeno, Masahiro; Ilchenko, Yuri; Iliadis, Dimitrios; Ilic, Nikolina; Imori, Masatoshi; Ince, Tayfun; Inigo-Golfin, Joaquin; Ioannou, Pavlos; Iodice, Mauro; Ippolito, Valerio; Irles Quiles, Adrian; Isaksson, Charlie; Ishikawa, Akimasa; Ishino, Masaya; Ishmukhametov, Renat; Issever, Cigdem; Istin, Serhat; Ivashin, Anton; Iwanski, Wieslaw; Iwasaki, Hiroyuki; Izen, Joseph; Izzo, Vincenzo; Jackson, Brett; Jackson, John; Jackson, Paul; Jaekel, Martin; Jain, Vivek; Jakobs, Karl; Jakobsen, Sune; Jakubek, Jan; Jana, Dilip; Jankowski, Ernest; Jansen, Eric; Jansen, Hendrik; Jantsch, Andreas; Janus, Michel; Jarlskog, Göran; Jeanty, Laura; Jelen, Kazimierz; Jen-La Plante, Imai; Jenni, Peter; Jeremie, Andrea; Jež, Pavel; Jézéquel, Stéphane; Jha, Manoj Kumar; Ji, Haoshuang; Ji, Weina; Jia, Jiangyong; Jiang, Yi; Jimenez Belenguer, Marcos; Jin, Ge; Jin, Shan; Jinnouchi, Osamu; Joergensen, Morten Dam; Joffe, David; Johansen, Lars; Johansen, Marianne; Johansson, Erik; Johansson, Per; Johnert, Sebastian; Johns, Kenneth; Jon-And, Kerstin; Jones, Graham; Jones, Roger; Jones, Tegid; Jones, Tim; Jonsson, Ove; Joram, Christian; Jorge, Pedro; Joseph, John; Jovicevic, Jelena; Jovin, Tatjana; Ju, Xiangyang; Jung, Christian; Jungst, Ralph Markus; Juranek, Vojtech; Jussel, Patrick; Juste Rozas, Aurelio; Kabachenko, Vasily; Kabana, Sonja; Kaci, Mohammed; Kaczmarska, Anna; Kadlecik, Peter; Kado, Marumi; Kagan, Harris; Kagan, Michael; Kaiser, Steffen; Kajomovitz, Enrique; Kalinin, Sergey; Kalinovskaya, Lidia; Kama, Sami; Kanaya, Naoko; Kaneda, Michiru; Kaneti, Steven; Kanno, Takayuki; Kantserov, Vadim; Kanzaki, Junichi; Kaplan, Benjamin; Kapliy, Anton; Kaplon, Jan; Kar, Deepak; Karagounis, Michael; Karagoz, Muge; Karnevskiy, Mikhail; Karr, Kristo; Kartvelishvili, Vakhtang; Karyukhin, Andrey; Kashif, Lashkar; Kasieczka, Gregor; Kass, Richard; Kastanas, Alex; Kataoka, Mayuko; Kataoka, Yousuke; Katsoufis, Elias; Katzy, Judith; Kaushik, Venkatesh; Kawagoe, Kiyotomo; Kawamoto, Tatsuo; Kawamura, Gen; Kayl, Manuel; Kazanin, Vassili; Kazarinov, Makhail; Keeler, Richard; Kehoe, Robert; Keil, Markus; Kekelidze, George; Kennedy, John; Kenney, Christopher John; Kenyon, Mike; Kepka, Oldrich; Kerschen, Nicolas; Kerševan, Borut Paul; Kersten, Susanne; Kessoku, Kohei; Keung, Justin; Khalil-zada, Farkhad; Khandanyan, Hovhannes; Khanov, Alexander; Kharchenko, Dmitri; Khodinov, Alexander; Kholodenko, Anatoli; Khomich, Andrei; Khoo, Teng Jian; Khoriauli, Gia; Khoroshilov, Andrey; Khovanskiy, Nikolai; Khovanskiy, Valery; Khramov, Evgeniy; Khubua, Jemal; Kim, Hyeon Jin; Kim, Min Suk; Kim, Shinhong; Kimura, Naoki; Kind, Oliver; King, Barry; King, Matthew; King, Robert Steven Beaufoy; Kirk, Julie; Kirsch, Lawrence; Kiryunin, Andrey; Kishimoto, Tomoe; Kisielewska, Danuta; Kittelmann, Thomas; Kiver, Andrey; Kladiva, Eduard; Klaiber-Lodewigs, Jonas; Klein, Max; Klein, Uta; Kleinknecht, Konrad; Klemetti, Miika; Klier, Amit; Klimek, Pawel; Klimentov, Alexei; Klingenberg, Reiner; Klinger, Joel Alexander; Klinkby, Esben; Klioutchnikova, Tatiana; Klok, Peter; Klous, Sander; Kluge, Eike-Erik; Kluge, Thomas; Kluit, Peter; Kluth, Stefan; Knecht, Neil; Kneringer, Emmerich; Knobloch, Juergen; Knoops, Edith; Knue, Andrea; Ko, Byeong Rok; Kobayashi, Tomio; Kobel, Michael; Kocian, Martin; Kodys, Peter; Köneke, Karsten; König, Adriaan; Koenig, Sebastian; Köpke, Lutz; Koetsveld, Folkert; Koevesarki, Peter; Koffas, Thomas; Koffeman, Els; Kogan, Lucy Anne; Kohn, Fabian; Kohout, Zdenek; Kohriki, Takashi; Koi, Tatsumi; Kokott, Thomas; Kolachev, Guennady; Kolanoski, Hermann; Kolesnikov, Vladimir; Koletsou, Iro; Koll, James; Kollefrath, Michael; Kolya, Scott; Komar, Aston; Komori, Yuto; Kondo, Takahiko; Kono, Takanori; Kononov, Anatoly; Konoplich, Rostislav; Konstantinidis, Nikolaos; Kootz, Andreas; Koperny, Stefan; Korcyl, Krzysztof; Kordas, Kostantinos; Koreshev, Victor; Korn, Andreas; Korol, Aleksandr; Korolkov, Ilya; Korolkova, Elena; Korotkov, Vladislav; Kortner, Oliver; Kortner, Sandra; Kostyukhin, Vadim; Kotamäki, Miikka Juhani; Kotov, Sergey; Kotov, Vladislav; Kotwal, Ashutosh; Kourkoumelis, Christine; Kouskoura, Vasiliki; Koutsman, Alex; Kowalewski, Robert Victor; Kowalski, Tadeusz; Kozanecki, Witold; Kozhin, Anatoly; Kral, Vlastimil; Kramarenko, Viktor; Kramberger, Gregor; Krasny, Mieczyslaw Witold; Krasznahorkay, Attila; Kraus, James; Kraus, Jana; Kreisel, Arik; Krejci, Frantisek; Kretzschmar, Jan; Krieger, Nina; Krieger, Peter; Kroeninger, Kevin; Kroha, Hubert; Kroll, Joe; Kroseberg, Juergen; Krstic, Jelena; Kruchonak, Uladzimir; Krüger, Hans; Kruker, Tobias; Krumnack, Nils; Krumshteyn, Zinovii; Kruth, Andre; Kubota, Takashi; Kuday, Sinan; Kuehn, Susanne; Kugel, Andreas; Kuhl, Thorsten; Kuhn, Dietmar; Kukhtin, Victor; Kulchitsky, Yuri; Kuleshov, Sergey; Kummer, Christian; Kuna, Marine; Kundu, Nikhil; Kunkle, Joshua; Kupco, Alexander; Kurashige, Hisaya; Kurata, Masakazu; Kurochkin, Yurii; Kus, Vlastimil; Kuwertz, Emma Sian; Kuze, Masahiro; Kvita, Jiri; Kwee, Regina; La Rosa, Alessandro; La Rotonda, Laura; Labarga, Luis; Labbe, Julien; Lablak, Said; Lacasta, Carlos; Lacava, Francesco; Lacker, Heiko; Lacour, Didier; Lacuesta, Vicente Ramón; Ladygin, Evgueni; Lafaye, Remi; Laforge, Bertrand; Lagouri, Theodota; Lai, Stanley; Laisne, Emmanuel; Lamanna, Massimo; Lampen, Caleb; Lampl, Walter; Lancon, Eric; Landgraf, Ulrich; Landon, Murrough; Lane, Jenna; Lange, Clemens; Lankford, Andrew; Lanni, Francesco; Lantzsch, Kerstin; Laplace, Sandrine; Lapoire, Cecile; Laporte, Jean-Francois; Lari, Tommaso; Larionov, Anatoly; Larner, Aimee; Lasseur, Christian; Lassnig, Mario; Laurelli, Paolo; Lavorini, Vincenzo; Lavrijsen, Wim; Laycock, Paul; Lazarev, Alexandre; Le Dortz, Olivier; Le Guirriec, Emmanuel; Le Maner, Christophe; Le Menedeu, Eve; Lebel, Céline; LeCompte, Thomas; Ledroit-Guillon, Fabienne Agnes Marie; Lee, Hurng-Chun; Lee, Jason; Lee, Shih-Chang; Lee, Lawrence; Lefebvre, Michel; Legendre, Marie; Leger, Annie; LeGeyt, Benjamin; Legger, Federica; Leggett, Charles; Lehmacher, Marc; Lehmann Miotto, Giovanna; Lei, Xiaowen; Leite, Marco Aurelio Lisboa; Leitner, Rupert; Lellouch, Daniel; Leltchouk, Mikhail; Lemmer, Boris; Lendermann, Victor; Leney, Katharine; Lenz, Tatiana; Lenzen, Georg; Lenzi, Bruno; Leonhardt, Kathrin; Leontsinis, Stefanos; Leroy, Claude; Lessard, Jean-Raphael; Lesser, Jonas; Lester, Christopher; Leung Fook Cheong, Annabelle; Levêque, Jessica; Levin, Daniel; Levinson, Lorne; Levitski, Mikhail; Lewis, Adrian; Lewis, George; Leyko, Agnieszka; Leyton, Michael; Li, Bo; Li, Haifeng; Li, Shu; Li, Xuefei; Liang, Zhijun; Liao, Hongbo; Liberti, Barbara; Lichard, Peter; Lichtnecker, Markus; Lie, Ki; Liebig, Wolfgang; Lifshitz, Ronen; Limbach, Christian; Limosani, Antonio; Limper, Maaike; Lin, Simon; Linde, Frank; Linnemann, James; Lipeles, Elliot; Lipinsky, Lukas; Lipniacka, Anna; Liss, Tony; Lissauer, David; Lister, Alison; Litke, Alan; Liu, Chuanlei; Liu, Dong; Liu, Hao; Liu, Jianbei; Liu, Minghui; Liu, Yanwen; Livan, Michele; Livermore, Sarah; Lleres, Annick; Llorente Merino, Javier; Lloyd, Stephen; Lobodzinska, Ewelina; Loch, Peter; Lockman, William; Loddenkoetter, Thomas; Loebinger, Fred; Loginov, Andrey; Loh, Chang Wei; Lohse, Thomas; Lohwasser, Kristin; Lokajicek, Milos; Loken, James; Lombardo, Vincenzo Paolo; Long, Robin Eamonn; Lopes, Lourenco; Lopez Mateos, David; Lorenz, Jeanette; Lorenzo Martinez, Narei; Losada, Marta; Loscutoff, Peter; Lo Sterzo, Francesco; Losty, Michael; Lou, Xinchou; Lounis, Abdenour; Loureiro, Karina; Love, Jeremy; Love, Peter; Lowe, Andrew; Lu, Feng; Lubatti, Henry; Luci, Claudio; Lucotte, Arnaud; Ludwig, Andreas; Ludwig, Dörthe; Ludwig, Inga; Ludwig, Jens; Luehring, Frederick; Luijckx, Guy; Lumb, Debra; Luminari, Lamberto; Lund, Esben; Lund-Jensen, Bengt; Lundberg, Björn; Lundberg, Johan; Lundquist, Johan; Lungwitz, Matthias; Lutz, Gerhard; Lynn, David; Lys, Jeremy; Lytken, Else; Ma, Hong; Ma, Lian Liang; Macana Goia, Jorge Andres; Maccarrone, Giovanni; Macchiolo, Anna; Maček, Boštjan; Machado Miguens, Joana; Mackeprang, Rasmus; Madaras, Ronald; Mader, Wolfgang; Maenner, Reinhard; Maeno, Tadashi; Mättig, Peter; Mättig, Stefan; Magnoni, Luca; Magradze, Erekle; Mahalalel, Yair; Mahboubi, Kambiz; Mahout, Gilles; Maiani, Camilla; Maidantchik, Carmen; Maio, Amélia; Majewski, Stephanie; Makida, Yasuhiro; Makovec, Nikola; Mal, Prolay; Malaescu, Bogdan; Malecki, Pawel; Malecki, Piotr; Maleev, Victor; Malek, Fairouz; Mallik, Usha; Malon, David; Malone, Caitlin; Maltezos, Stavros; Malyshev, Vladimir; Malyukov, Sergei; Mameghani, Raphael; Mamuzic, Judita; Manabe, Atsushi; Mandelli, Luciano; Mandić, Igor; Mandrysch, Rocco; Maneira, José; Mangeard, Pierre-Simon; Manhaes de Andrade Filho, Luciano; Manjavidze, Ioseb; Mann, Alexander; Manning, Peter; Manousakis-Katsikakis, Arkadios; Mansoulie, Bruno; Manz, Andreas; Mapelli, Alessandro; Mapelli, Livio; March, Luis; Marchand, Jean-Francois; Marchese, Fabrizio; Marchiori, Giovanni; Marcisovsky, Michal; Marino, Christopher; Marroquim, Fernando; Marshall, Robin; Marshall, Zach; Martens, Kalen; Marti-Garcia, Salvador; Martin, Andrew; Martin, Brian; Martin, Brian; Martin, Franck Francois; Martin, Jean-Pierre; Martin, Philippe; Martin, Tim; Martin, Victoria Jane; Martin dit Latour, Bertrand; Martin-Haugh, Stewart; Martinez, Mario; Martinez Outschoorn, Verena; Martyniuk, Alex; Marx, Marilyn; Marzano, Francesco; Marzin, Antoine; Masetti, Lucia; Mashimo, Tetsuro; Mashinistov, Ruslan; Masik, Jiri; Maslennikov, Alexey; Massa, Ignazio; Massaro, Graziano; Massol, Nicolas; Mastrandrea, Paolo; Mastroberardino, Anna; Masubuchi, Tatsuya; Matricon, Pierre; Matsumoto, Hiroshi; Matsunaga, Hiroyuki; Matsushita, Takashi; Mattravers, Carly; Maugain, Jean-Marie; Maurer, Julien; Maxfield, Stephen; Maximov, Dmitriy; May, Edward; Mayne, Anna; Mazini, Rachid; Mazur, Michael; Mazzanti, Marcello; Mc Kee, Shawn Patrick; McCarn, Allison; McCarthy, Robert; McCarthy, Tom; McCubbin, Norman; McFarlane, Kenneth; Mcfayden, Josh; McGlone, Helen; Mchedlidze, Gvantsa; McLaren, Robert Andrew; Mclaughlan, Tom; McMahon, Steve; McPherson, Robert; Meade, Andrew; Mechnich, Joerg; Mechtel, Markus; Medinnis, Mike; Meera-Lebbai, Razzak; Meguro, Tatsuma; Mehdiyev, Rashid; Mehlhase, Sascha; Mehta, Andrew; Meier, Karlheinz; Meirose, Bernhard; Melachrinos, Constantinos; Mellado Garcia, Bruce Rafael; Mendoza Navas, Luis; Meng, Zhaoxia; Mengarelli, Alberto; Menke, Sven; Menot, Claude; Meoni, Evelin; Mercurio, Kevin Michael; Mermod, Philippe; Merola, Leonardo; Meroni, Chiara; Merritt, Frank; Merritt, Hayes; Messina, Andrea; Metcalfe, Jessica; Mete, Alaettin Serhan; Meyer, Carsten; Meyer, Christopher; Meyer, Jean-Pierre; Meyer, Jochen; Meyer, Joerg; Meyer, Thomas Christian; Meyer, W Thomas; Miao, Jiayuan; Michal, Sebastien; Micu, Liliana; Middleton, Robin; Migas, Sylwia; Mijović, Liza; Mikenberg, Giora; Mikestikova, Marcela; Mikuž, Marko; Miller, David; Miller, Robert; Mills, Bill; Mills, Corrinne; Milov, Alexander; Milstead, David; Milstein, Dmitry; Minaenko, Andrey; Miñano Moya, Mercedes; Minashvili, Irakli; Mincer, Allen; Mindur, Bartosz; Mineev, Mikhail; Ming, Yao; Mir, Lluisa-Maria; Mirabelli, Giovanni; Miralles Verge, Lluis; Misiejuk, Andrzej; Mitrevski, Jovan; Mitrofanov, Gennady; Mitsou, Vasiliki A; Mitsui, Shingo; Miyagawa, Paul; Miyazaki, Kazuki; Mjörnmark, Jan-Ulf; Moa, Torbjoern; Mockett, Paul; Moed, Shulamit; Moeller, Victoria; Mönig, Klaus; Möser, Nicolas; Mohapatra, Soumya; Mohr, Wolfgang; Mohrdieck-Möck, Susanne; Moisseev, Artemy; Moles-Valls, Regina; Molina-Perez, Jorge; Monk, James; Monnier, Emmanuel; Montesano, Simone; Monticelli, Fernando; Monzani, Simone; Moore, Roger; Moorhead, Gareth; Mora Herrera, Clemencia; Moraes, Arthur; Morange, Nicolas; Morel, Julien; Morello, Gianfranco; Moreno, Deywis; Moreno Llácer, María; Morettini, Paolo; Morgenstern, Marcus; Morii, Masahiro; Morin, Jerome; Morley, Anthony Keith; Mornacchi, Giuseppe; Morozov, Sergey; Morris, John; Morvaj, Ljiljana; Moser, Hans-Guenther; Mosidze, Maia; Moss, Josh; Mount, Richard; Mountricha, Eleni; Mouraviev, Sergei; Moyse, Edward; Mudrinic, Mihajlo; Mueller, Felix; Mueller, James; Mueller, Klemens; Müller, Thomas; Mueller, Timo; Muenstermann, Daniel; Muir, Alex; Munwes, Yonathan; Murray, Bill; Mussche, Ido; Musto, Elisa; Myagkov, Alexey; Myska, Miroslav; Nadal, Jordi; Nagai, Koichi; Nagano, Kunihiro; Nagarkar, Advait; Nagasaka, Yasushi; Nagel, Martin; Nairz, Armin Michael; Nakahama, Yu; Nakamura, Koji; Nakamura, Tomoaki; Nakano, Itsuo; Nanava, Gizo; Napier, Austin; Narayan, Rohin; Nash, Michael; Nation, Nigel; Nattermann, Till; Naumann, Thomas; Navarro, Gabriela; Neal, Homer; Nebot, Eduardo; Nechaeva, Polina; Neep, Thomas James; Negri, Andrea; Negri, Guido; Nektarijevic, Snezana; Nelson, Andrew; Nelson, Silke; Nelson, Timothy Knight; Nemecek, Stanislav; Nemethy, Peter; Nepomuceno, Andre Asevedo; Nessi, Marzio; Neubauer, Mark; Neusiedl, Andrea; Neves, Ricardo; Nevski, Pavel; Newman, Paul; Nguyen Thi Hong, Van; Nickerson, Richard; Nicolaidou, Rosy; Nicolas, Ludovic; Nicquevert, Bertrand; Niedercorn, Francois; Nielsen, Jason; Niinikoski, Tapio; Nikiforou, Nikiforos; Nikiforov, Andriy; Nikolaenko, Vladimir; Nikolaev, Kirill; Nikolic-Audit, Irena; Nikolics, Katalin; Nikolopoulos, Konstantinos; Nilsen, Henrik; Nilsson, Paul; Ninomiya, Yoichi; Nisati, Aleandro; Nishiyama, Tomonori; Nisius, Richard; Nodulman, Lawrence; Nomachi, Masaharu; Nomidis, Ioannis; Nordberg, Markus; Nordkvist, Bjoern; Norton, Peter; Novakova, Jana; Nozaki, Mitsuaki; Nozka, Libor; Nugent, Ian Michael; Nuncio-Quiroz, Adriana-Elizabeth; Nunes Hanninger, Guilherme; Nunnemann, Thomas; Nurse, Emily; O'Brien, Brendan Joseph; O'Neale, Steve; O'Neil, Dugan; O'Shea, Val; Oakes, Louise Beth; Oakham, Gerald; Oberlack, Horst; Ocariz, Jose; Ochi, Atsuhiko; Oda, Susumu; Odaka, Shigeru; Odier, Jerome; Ogren, Harold; Oh, Alexander; Oh, Seog; Ohm, Christian; Ohshima, Takayoshi; Ohshita, Hidetoshi; Ohsugi, Takashi; Okada, Shogo; Okawa, Hideki; Okumura, Yasuyuki; Okuyama, Toyonobu; Olariu, Albert; Olcese, Marco; Olchevski, Alexander; Olivares Pino, Sebastian Andres; Oliveira, Miguel Alfonso; Oliveira Damazio, Denis; Oliver Garcia, Elena; Olivito, Dominick; Olszewski, Andrzej; Olszowska, Jolanta; Omachi, Chihiro; Onofre, António; Onyisi, Peter; Oram, Christopher; Oreglia, Mark; Oren, Yona; Orestano, Domizia; Orlov, Iliya; Oropeza Barrera, Cristina; Orr, Robert; Osculati, Bianca; Ospanov, Rustem; Osuna, Carlos; Otero y Garzon, Gustavo; Ottersbach, John; Ouchrif, Mohamed; Ouellette, Eric; Ould-Saada, Farid; Ouraou, Ahmimed; Ouyang, Qun; Ovcharova, Ana; Owen, Mark; Owen, Simon; Ozcan, Veysi Erkcan; Ozturk, Nurcan; Pacheco Pages, Andres; Padilla Aranda, Cristobal; Pagan Griso, Simone; Paganis, Efstathios; Paige, Frank; Pais, Preema; Pajchel, Katarina; Palacino, Gabriel; Paleari, Chiara; Palestini, Sandro; Pallin, Dominique; Palma, Alberto; Palmer, Jody; Pan, Yibin; Panagiotopoulou, Evgenia; Panes, Boris; Panikashvili, Natalia; Panitkin, Sergey; Pantea, Dan; Panuskova, Monika; Paolone, Vittorio; Papadelis, Aras; Papadopoulou, Theodora; Paramonov, Alexander; Paredes Hernandez, Daniela; Park, Woochun; Parker, Andy; Parodi, Fabrizio; Parsons, John; Parzefall, Ulrich; Pasqualucci, Enrico; Passaggio, Stefano; Passeri, Antonio; Pastore, Fernanda; Pastore, Francesca; Pásztor, Gabriella; Pataraia, Sophio; Patel, Nikhul; Pater, Joleen; Patricelli, Sergio; Pauly, Thilo; Pecsy, Martin; Pedraza Morales, Maria Isabel; Peleganchuk, Sergey; Peng, Haiping; Pengo, Ruggero; Penning, Bjoern; Penson, Alexander; Penwell, John; Perantoni, Marcelo; Perez, Kerstin; Perez Cavalcanti, Tiago; Perez Codina, Estel; Pérez García-Estañ, María Teresa; Perez Reale, Valeria; Perini, Laura; Pernegger, Heinz; Perrino, Roberto; Perrodo, Pascal; Persembe, Seda; Perus, Antoine; Peshekhonov, Vladimir; Peters, Krisztian; Petersen, Brian; Petersen, Jorgen; Petersen, Troels; Petit, Elisabeth; Petridis, Andreas; Petridou, Chariclia; Petrolo, Emilio; Petrucci, Fabrizio; Petschull, Dennis; Petteni, Michele; Pezoa, Raquel; Phan, Anna; Phillips, Peter William; Piacquadio, Giacinto; Picazio, Attilio; Piccaro, Elisa; Piccinini, Maurizio; Piec, Sebastian Marcin; Piegaia, Ricardo; Pignotti, David; Pilcher, James; Pilkington, Andrew; Pina, João Antonio; Pinamonti, Michele; Pinder, Alex; Pinfold, James; Ping, Jialun; Pinto, Belmiro; Pirotte, Olivier; Pizio, Caterina; Plamondon, Mathieu; Pleier, Marc-Andre; Pleskach, Anatoly; Poblaguev, Andrei; Poddar, Sahill; Podlyski, Fabrice; Poggioli, Luc; Poghosyan, Tatevik; Pohl, Martin; Polci, Francesco; Polesello, Giacomo; Policicchio, Antonio; Polini, Alessandro; Poll, James; Polychronakos, Venetios; Pomarede, Daniel Marc; Pomeroy, Daniel; Pommès, Kathy; Pontecorvo, Ludovico; Pope, Bernard; Popeneciu, Gabriel Alexandru; Popovic, Dragan; Poppleton, Alan; Portell Bueso, Xavier; Posch, Christoph; Pospelov, Guennady; Pospisil, Stanislav; Potrap, Igor; Potter, Christina; Potter, Christopher; Poulard, Gilbert; Poveda, Joaquin; Pozdnyakov, Valery; Prabhu, Robindra; Pralavorio, Pascal; Pranko, Aliaksandr; Prasad, Srivas; Pravahan, Rishiraj; Prell, Soeren; Pretzl, Klaus Peter; Pribyl, Lukas; Price, Darren; Price, Joe; Price, Lawrence; Price, Michael John; Prieur, Damien; Primavera, Margherita; Prokofiev, Kirill; Prokoshin, Fedor; Protopopescu, Serban; Proudfoot, James; Prudent, Xavier; Przybycien, Mariusz; Przysiezniak, Helenka; Psoroulas, Serena; Ptacek, Elizabeth; Pueschel, Elisa; Purdham, John; Purohit, Milind; Puzo, Patrick; Pylypchenko, Yuriy; Qian, Jianming; Qian, Zuxuan; Qin, Zhonghua; Quadt, Arnulf; Quarrie, David; Quayle, William; Quinonez, Fernando; Raas, Marcel; Radescu, Voica; Radics, Balint; Radloff, Peter; Rador, Tonguc; Ragusa, Francesco; Rahal, Ghita; Rahimi, Amir; Rahm, David; Rajagopalan, Srinivasan; Rammensee, Michael; Rammes, Marcus; Randle-Conde, Aidan Sean; Randrianarivony, Koloina; Ratoff, Peter; Rauscher, Felix; Rave, Tobias Christian; Raymond, Michel; Read, Alexander Lincoln; Rebuzzi, Daniela; Redelbach, Andreas; Redlinger, George; Reece, Ryan; Reeves, Kendall; Reichold, Armin; Reinherz-Aronis, Erez; Reinsch, Andreas; Reisinger, Ingo; Rembser, Christoph; Ren, Zhongliang; Renaud, Adrien; Rescigno, Marco; Resconi, Silvia; Resende, Bernardo; Reznicek, Pavel; Rezvani, Reyhaneh; Richards, Alexander; Richter, Robert; Richter-Was, Elzbieta; Ridel, Melissa; Rijpstra, Manouk; Rijssenbeek, Michael; Rimoldi, Adele; Rinaldi, Lorenzo; Rios, Ryan Randy; Riu, Imma; Rivoltella, Giancesare; Rizatdinova, Flera; Rizvi, Eram; Robertson, Steven; Robichaud-Veronneau, Andree; Robinson, Dave; Robinson, James; Robson, Aidan; Rocha de Lima, Jose Guilherme; Roda, Chiara; Roda Dos Santos, Denis; Rodriguez, Diego; Roe, Adam; Roe, Shaun; Røhne, Ole; Rojo, Victoria; Rolli, Simona; Romaniouk, Anatoli; Romano, Marino; Romanov, Victor; Romeo, Gaston; Romero Adam, Elena; Roos, Lydia; Ros, Eduardo; Rosati, Stefano; Rosbach, Kilian; Rose, Anthony; Rose, Matthew; Rosenbaum, Gabriel; Rosenberg, Eli; Rosendahl, Peter Lundgaard; Rosenthal, Oliver; Rosselet, Laurent; Rossetti, Valerio; Rossi, Elvira; Rossi, Leonardo Paolo; Rotaru, Marina; Roth, Itamar; Rothberg, Joseph; Rousseau, David; Royon, Christophe; Rozanov, Alexander; Rozen, Yoram; Ruan, Xifeng; Rubinskiy, Igor; Ruckert, Benjamin; Ruckstuhl, Nicole; Rud, Viacheslav; Rudolph, Christian; Rudolph, Gerald; Rühr, Frederik; Ruggieri, Federico; Ruiz-Martinez, Aranzazu; Rumiantsev, Viktor; Rumyantsev, Leonid; Runge, Kay; Rurikova, Zuzana; Rusakovich, Nikolai; Rutherfoord, John; Ruwiedel, Christoph; Ruzicka, Pavel; Ryabov, Yury; Ryadovikov, Vasily; Ryan, Patrick; Rybar, Martin; Rybkin, Grigori; Ryder, Nick; Rzaeva, Sevda; Saavedra, Aldo; Sadeh, Iftach; Sadrozinski, Hartmut; Sadykov, Renat; Safai Tehrani, Francesco; Sakamoto, Hiroshi; Salamanna, Giuseppe; Salamon, Andrea; Saleem, Muhammad; Salihagic, Denis; Salnikov, Andrei; Salt, José; Salvachua Ferrando, Belén; Salvatore, Daniela; Salvatore, Pasquale Fabrizio; Salvucci, Antonio; Salzburger, Andreas; Sampsonidis, Dimitrios; Samset, Björn Hallvard; Sanchez, Arturo; Sanchez Martinez, Victoria; Sandaker, Heidi; Sander, Heinz Georg; Sanders, Michiel; Sandhoff, Marisa; Sandoval, Tanya; Sandoval, Carlos; Sandstroem, Rikard; Sandvoss, Stephan; Sankey, Dave; Sansoni, Andrea; Santamarina Rios, Cibran; Santoni, Claudio; Santonico, Rinaldo; Santos, Helena; Sapronov, Andrey; Saraiva, João; Sarangi, Tapas; Sarkisyan-Grinbaum, Edward; Sarri, Francesca; Sartisohn, Georg; Sasaki, Osamu; Sasao, Noboru; Satsounkevitch, Igor; Sauvage, Gilles; Sauvan, Emmanuel; Sauvan, Jean-Baptiste; Savard, Pierre; Savinov, Vladimir; Savu, Dan Octavian; Sawyer, Lee; Saxon, David; Says, Louis-Pierre; Sbarra, Carla; Sbrizzi, Antonio; Scallon, Olivia; Scannicchio, Diana; Scarcella, Mark; Schaarschmidt, Jana; Schacht, Peter; Schäfer, Uli; Schaepe, Steffen; Schaetzel, Sebastian; Schaffer, Arthur; Schaile, Dorothee; Schamberger, R~Dean; Schamov, Andrey; Scharf, Veit; Schegelsky, Valery; Scheirich, Daniel; Schernau, Michael; Scherzer, Max; Schiavi, Carlo; Schieck, Jochen; Schioppa, Marco; Schlenker, Stefan; Schlereth, James; Schmidt, Evelyn; Schmieden, Kristof; Schmitt, Christian; Schmitt, Sebastian; Schmitz, Martin; Schöning, André; Schott, Matthias; Schouten, Doug; Schovancova, Jaroslava; Schram, Malachi; Schroeder, Christian; Schroer, Nicolai; Schuler, Georges; Schultens, Martin Johannes; Schultes, Joachim; Schultz-Coulon, Hans-Christian; Schulz, Holger; Schumacher, Jan; Schumacher, Markus; Schumm, Bruce; Schune, Philippe; Schwanenberger, Christian; Schwartzman, Ariel; Schwemling, Philippe; Schwienhorst, Reinhard; Schwierz, Rainer; Schwindling, Jerome; Schwindt, Thomas; Schwoerer, Maud; Scott, Bill; Searcy, Jacob; Sedov, George; Sedykh, Evgeny; Segura, Ester; Seidel, Sally; Seiden, Abraham; Seifert, Frank; Seixas, José; Sekhniaidze, Givi; Selbach, Karoline Elfriede; Seliverstov, Dmitry; Sellden, Bjoern; Sellers, Graham; Seman, Michal; Semprini-Cesari, Nicola; Serfon, Cedric; Serin, Laurent; Serkin, Leonid; Seuster, Rolf; Severini, Horst; Sevior, Martin; Sfyrla, Anna; Shabalina, Elizaveta; Shamim, Mansoora; Shan, Lianyou; Shank, James; Shao, Qi Tao; Shapiro, Marjorie; Shatalov, Pavel; Shaver, Leif; Shaw, Kate; Sherman, Daniel; Sherwood, Peter; Shibata, Akira; Shichi, Hideharu; Shimizu, Shima; Shimojima, Makoto; Shin, Taeksu; Shiyakova, Maria; Shmeleva, Alevtina; Shochet, Mel; Short, Daniel; Shrestha, Suyog; Shulga, Evgeny; Shupe, Michael; Sicho, Petr; Sidoti, Antonio; Siegert, Frank; Sijacki, Djordje; Silbert, Ohad; Silva, José; Silver, Yiftah; Silverstein, Daniel; Silverstein, Samuel; Simak, Vladislav; Simard, Olivier; Simic, Ljiljana; Simion, Stefan; Simmons, Brinick; Simonyan, Margar; Sinervo, Pekka; Sinev, Nikolai; Sipica, Valentin; Siragusa, Giovanni; Sircar, Anirvan; Sisakyan, Alexei; Sivoklokov, Serguei; Sjölin, Jörgen; Sjursen, Therese; Skinnari, Louise Anastasia; Skottowe, Hugh Philip; Skovpen, Kirill; Skubic, Patrick; Skvorodnev, Nikolai; Slater, Mark; Slavicek, Tomas; Sliwa, Krzysztof; Sloper, John erik; Smakhtin, Vladimir; Smart, Ben; Smirnov, Sergei; Smirnov, Yury; Smirnova, Lidia; Smirnova, Oxana; Smith, Ben Campbell; Smith, Douglas; Smith, Kenway; Smizanska, Maria; Smolek, Karel; Snesarev, Andrei; Snow, Steve; Snow, Joel; Snuverink, Jochem; Snyder, Scott; Soares, Mara; Sobie, Randall; Sodomka, Jaromir; Soffer, Abner; Solans, Carlos; Solar, Michael; Solc, Jaroslav; Soldatov, Evgeny; Soldevila, Urmila; Solfaroli Camillocci, Elena; Solodkov, Alexander; Solovyanov, Oleg; Soni, Nitesh; Sopko, Vit; Sopko, Bruno; Sosebee, Mark; Soualah, Rachik; Soukharev, Andrey; Spagnolo, Stefania; Spanò, Francesco; Spighi, Roberto; Spigo, Giancarlo; Spila, Federico; Spiwoks, Ralf; Spousta, Martin; Spreitzer, Teresa; Spurlock, Barry; St Denis, Richard Dante; Stahlman, Jonathan; Stamen, Rainer; Stanecka, Ewa; Stanek, Robert; Stanescu, Cristian; Stapnes, Steinar; Starchenko, Evgeny; Stark, Jan; Staroba, Pavel; Starovoitov, Pavel; Staude, Arnold; Stavina, Pavel; Steele, Genevieve; Steinbach, Peter; Steinberg, Peter; Stekl, Ivan; Stelzer, Bernd; Stelzer, Harald Joerg; Stelzer-Chilton, Oliver; Stenzel, Hasko; Stern, Sebastian; Stevenson, Kyle; Stewart, Graeme; Stillings, Jan Andre; Stockton, Mark; Stoerig, Kathrin; Stoicea, Gabriel; Stonjek, Stefan; Strachota, Pavel; Stradling, Alden; Straessner, Arno; Strandberg, Jonas; Strandberg, Sara; Strandlie, Are; Strang, Michael; Strauss, Emanuel; Strauss, Michael; Strizenec, Pavol; Ströhmer, Raimund; Strom, David; Strong, John; Stroynowski, Ryszard; Strube, Jan; Stugu, Bjarne; Stumer, Iuliu; Stupak, John; Sturm, Philipp; Styles, Nicholas Adam; Soh, Dart-yin; Su, Dong; Subramania, Halasya Siva; Succurro, Antonella; Sugaya, Yorihito; Sugimoto, Takuya; Suhr, Chad; Suita, Koichi; Suk, Michal; Sulin, Vladimir; Sultansoy, Saleh; Sumida, Toshi; Sun, Xiaohu; Sundermann, Jan Erik; Suruliz, Kerim; Sushkov, Serge; Susinno, Giancarlo; Sutton, Mark; Suzuki, Yu; Suzuki, Yuta; Svatos, Michal; Sviridov, Yuri; Swedish, Stephen; Sykora, Ivan; Sykora, Tomas; Szeless, Balazs; Sánchez, Javier; Ta, Duc; Tackmann, Kerstin; Taffard, Anyes; Tafirout, Reda; Taiblum, Nimrod; Takahashi, Yuta; Takai, Helio; Takashima, Ryuichi; Takeda, Hiroshi; Takeshita, Tohru; Takubo, Yosuke; Talby, Mossadek; Talyshev, Alexey; Tamsett, Matthew; Tanaka, Junichi; Tanaka, Reisaburo; Tanaka, Satoshi; Tanaka, Shuji; Tanaka, Yoshito; Tanasijczuk, Andres Jorge; Tani, Kazutoshi; Tannoury, Nancy; Tappern, Geoffrey; Tapprogge, Stefan; Tardif, Dominique; Tarem, Shlomit; Tarrade, Fabien; Tartarelli, Giuseppe Francesco; Tas, Petr; Tasevsky, Marek; Tassi, Enrico; Tatarkhanov, Mous; Tayalati, Yahya; Taylor, Christopher; Taylor, Frank; Taylor, Geoffrey; Taylor, Wendy; Teinturier, Marthe; Teixeira Dias Castanheira, Matilde; Teixeira-Dias, Pedro; Temming, Kim Katrin; Ten Kate, Herman; Teng, Ping-Kun; Terada, Susumu; Terashi, Koji; Terron, Juan; Testa, Marianna; Teuscher, Richard; Thadome, Jocelyn; Therhaag, Jan; Theveneaux-Pelzer, Timothée; Thioye, Moustapha; Thoma, Sascha; Thomas, Juergen; Thompson, Emily; Thompson, Paul; Thompson, Peter; Thompson, Stan; Thomsen, Lotte Ansgaard; Thomson, Evelyn; Thomson, Mark; Thun, Rudolf; Tian, Feng; Tibbetts, Mark James; Tic, Tomáš; Tikhomirov, Vladimir; Tikhonov, Yury; Timoshenko, Sergey; Tipton, Paul; Tique Aires Viegas, Florbela De Jes; Tisserant, Sylvain; Toczek, Barbara; Todorov, Theodore; Todorova-Nova, Sharka; Toggerson, Brokk; Tojo, Junji; Tokár, Stanislav; Tokunaga, Kaoru; Tokushuku, Katsuo; Tollefson, Kirsten; Tomoto, Makoto; Tompkins, Lauren; Toms, Konstantin; Tong, Guoliang; Tonoyan, Arshak; Topfel, Cyril; Topilin, Nikolai; Torchiani, Ingo; Torrence, Eric; Torres, Heberth; Torró Pastor, Emma; Toth, Jozsef; Touchard, Francois; Tovey, Daniel; Trefzger, Thomas; Tremblet, Louis; Tricoli, Alesandro; Trigger, Isabel Marian; Trincaz-Duvoid, Sophie; Trinh, Thi Nguyet; Tripiana, Martin; Trischuk, William; Trivedi, Arjun; Trocmé, Benjamin; Troncon, Clara; Trottier-McDonald, Michel; Trzebinski, Maciej; Trzupek, Adam; Tsarouchas, Charilaos; Tseng, Jeffrey; Tsiakiris, Menelaos; Tsiareshka, Pavel; Tsionou, Dimitra; Tsipolitis, Georgios; Tsiskaridze, Vakhtang; Tskhadadze, Edisher; Tsukerman, Ilya; Tsulaia, Vakhtang; Tsung, Jieh-Wen; Tsuno, Soshi; Tsybychev, Dmitri; Tua, Alan; Tudorache, Alexandra; Tudorache, Valentina; Tuggle, Joseph; Turala, Michal; Turecek, Daniel; Turk Cakir, Ilkay; Turlay, Emmanuel; Turra, Ruggero; Tuts, Michael; Tykhonov, Andrii; Tylmad, Maja; Tyndel, Mike; Tzanakos, George; Uchida, Kirika; Ueda, Ikuo; Ueno, Ryuichi; Ugland, Maren; Uhlenbrock, Mathias; Uhrmacher, Michael; Ukegawa, Fumihiko; Unal, Guillaume; Underwood, David; Undrus, Alexander; Unel, Gokhan; Unno, Yoshinobu; Urbaniec, Dustin; Usai, Giulio; Uslenghi, Massimiliano; Vacavant, Laurent; Vacek, Vaclav; Vachon, Brigitte; Vahsen, Sven; Valenta, Jan; Valente, Paolo; Valentinetti, Sara; Valkar, Stefan; Valladolid Gallego, Eva; Vallecorsa, Sofia; Valls Ferrer, Juan Antonio; van der Graaf, Harry; van der Kraaij, Erik; Van Der Leeuw, Robin; van der Poel, Egge; van der Ster, Daniel; van Eldik, Niels; van Gemmeren, Peter; van Kesteren, Zdenko; van Vulpen, Ivo; Vanadia, Marco; Vandelli, Wainer; Vandoni, Giovanna; Vaniachine, Alexandre; Vankov, Peter; Vannucci, Francois; Varela Rodriguez, Fernando; Vari, Riccardo; Varnes, Erich; Varouchas, Dimitris; Vartapetian, Armen; Varvell, Kevin; Vassilakopoulos, Vassilios; Vazeille, Francois; Vazquez Schroeder, Tamara; Vegni, Guido; Veillet, Jean-Jacques; Vellidis, Constantine; Veloso, Filipe; Veness, Raymond; Veneziano, Stefano; Ventura, Andrea; Ventura, Daniel; Venturi, Manuela; Venturi, Nicola; Vercesi, Valerio; Verducci, Monica; Verkerke, Wouter; Vermeulen, Jos; Vest, Anja; Vetterli, Michel; Vichou, Irene; Vickey, Trevor; Vickey Boeriu, Oana Elena; Viehhauser, Georg; Viel, Simon; Villa, Mauro; Villaplana Perez, Miguel; Vilucchi, Elisabetta; Vincter, Manuella; Vinek, Elisabeth; Vinogradov, Vladimir; Virchaux, Marc; Virzi, Joseph; Vitells, Ofer; Viti, Michele; Vivarelli, Iacopo; Vives Vaque, Francesc; Vlachos, Sotirios; Vladoiu, Dan; Vlasak, Michal; Vlasov, Nikolai; Vogel, Adrian; Vokac, Petr; Volpi, Guido; Volpi, Matteo; Volpini, Giovanni; von der Schmitt, Hans; von Loeben, Joerg; von Radziewski, Holger; von Toerne, Eckhard; Vorobel, Vit; Vorobiev, Alexander; Vorwerk, Volker; Vos, Marcel; Voss, Rudiger; Voss, Thorsten Tobias; Vossebeld, Joost; Vranjes, Nenad; Vranjes Milosavljevic, Marija; Vrba, Vaclav; Vreeswijk, Marcel; Vu Anh, Tuan; Vuillermet, Raphael; Vukotic, Ilija; Wagner, Wolfgang; Wagner, Peter; Wahlen, Helmut; Wakabayashi, Jun; Walbersloh, Jorg; Walch, Shannon; Walder, James; Walker, Rodney; Walkowiak, Wolfgang; Wall, Richard; Waller, Peter; Wang, Chiho; Wang, Haichen; Wang, Hulin; Wang, Jike; Wang, Jin; Wang, Joshua C; Wang, Rui; Wang, Song-Ming; Warburton, Andreas; Ward, Patricia; Warsinsky, Markus; Watkins, Peter; Watson, Alan; Watson, Ian; Watson, Miriam; Watts, Gordon; Watts, Stephen; Waugh, Anthony; Waugh, Ben; Weber, Marc; Weber, Michele; Weber, Pavel; Weidberg, Anthony; Weigell, Philipp; Weingarten, Jens; Weiser, Christian; Wellenstein, Hermann; Wells, Phillippa; Wenaus, Torre; Wendland, Dennis; Wendler, Shanti; Weng, Zhili; Wengler, Thorsten; Wenig, Siegfried; Wermes, Norbert; Werner, Matthias; Werner, Per; Werth, Michael; Wessels, Martin; Weydert, Carole; Whalen, Kathleen; Wheeler-Ellis, Sarah Jane; Whitaker, Scott; White, Andrew; White, Martin; Whitehead, Samuel Robert; Whiteson, Daniel; Whittington, Denver; Wicek, Francois; Wicke, Daniel; Wickens, Fred; Wiedenmann, Werner; Wielers, Monika; Wienemann, Peter; Wiglesworth, Craig; Wiik-Fuchs, Liv Antje Mari; Wijeratne, Peter Alexander; Wildauer, Andreas; Wildt, Martin Andre; Wilhelm, Ivan; Wilkens, Henric George; Will, Jonas Zacharias; Williams, Eric; Williams, Hugh; Willis, William; Willocq, Stephane; Wilson, John; Wilson, Michael Galante; Wilson, Alan; Wingerter-Seez, Isabelle; Winkelmann, Stefan; Winklmeier, Frank; Wittgen, Matthias; Wolter, Marcin Wladyslaw; Wolters, Helmut; Wong, Wei-Cheng; Wooden, Gemma; Wosiek, Barbara; Wotschack, Jorg; Woudstra, Martin; Wozniak, Krzysztof; Wraight, Kenneth; Wright, Catherine; Wright, Michael; Wrona, Bozydar; Wu, Sau Lan; Wu, Xin; Wu, Yusheng; Wulf, Evan; Wunstorf, Renate; Wynne, Benjamin; Xella, Stefania; Xiao, Meng; Xie, Song; Xie, Yigang; Xu, Chao; Xu, Da; Xu, Guofa; Yabsley, Bruce; Yacoob, Sahal; Yamada, Miho; Yamaguchi, Hiroshi; Yamamoto, Akira; Yamamoto, Kyoko; Yamamoto, Shimpei; Yamamura, Taiki; Yamanaka, Takashi; Yamaoka, Jared; Yamazaki, Takayuki; Yamazaki, Yuji; Yan, Zhen; Yang, Haijun; Yang, Un-Ki; Yang, Yi; Yang, Yi; Yang, Zhaoyu; Yanush, Serguei; Yao, Yushu; Yasu, Yoshiji; Ybeles Smit, Gabriel Valentijn; Ye, Jingbo; Ye, Shuwei; Yilmaz, Metin; Yoosoofmiya, Reza; Yorita, Kohei; Yoshida, Riktura; Young, Charles; Youssef, Saul; Yu, Dantong; Yu, Jaehoon; Yu, Jie; Yuan, Li; Yurkewicz, Adam; Zabinski, Bartlomiej; Zaets, Vassilli; Zaidan, Remi; Zaitsev, Alexander; Zajacova, Zuzana; Zanello, Lucia; Zaytsev, Alexander; Zeitnitz, Christian; Zeller, Michael; Zeman, Martin; Zemla, Andrzej; Zendler, Carolin; Zenin, Oleg; Ženiš, Tibor; Zinonos, Zinonas; Zenz, Seth; Zerwas, Dirk; Zevi della Porta, Giovanni; Zhan, Zhichao; Zhang, Dongliang; Zhang, Huaqiao; Zhang, Jinlong; Zhang, Xueyao; Zhang, Zhiqing; Zhao, Long; Zhao, Tianchi; Zhao, Zhengguo; Zhemchugov, Alexey; Zheng, Shuchen; Zhong, Jiahang; Zhou, Bing; Zhou, Ning; Zhou, Yue; Zhu, Cheng Guang; Zhu, Hongbo; Zhu, Junjie; Zhu, Yingchun; Zhuang, Xuai; Zhuravlov, Vadym; Zieminska, Daria; Zimmermann, Robert; Zimmermann, Simone; Zimmermann, Stephanie; Ziolkowski, Michael; Zitoun, Robert; Živković, Lidija; Zmouchko, Viatcheslav; Zobernig, Georg; Zoccoli, Antonio; Zolnierowski, Yves; Zsenei, Andras; zur Nedden, Martin; Zutshi, Vishnu; Zwalinski, Lukasz
2012-01-01
A QCD analysis is reported of ATLAS data on inclusive W and Z boson production in pp collisions at the LHC, jointly with ep deep inelastic scattering data from HERA. The ATLAS data exhibit sensitivity to the light quark sea composition and magnitude at Bjorken x ~ 0.01. Specifically, the data support the hypothesis of a symmetric composition of the light quark sea at low x. The ratio of the strange-to-down sea quark distributions is determined to be 1.00(+0.25-0.28) at absolute four-momentum transfer squared Q^2 = 1.9 GeV^2 and x = 0.023.
Semi-Dirac points in phononic crystals
Zhang, Xiujuan
2014-01-01
A semi-Dirac cone refers to a peculiar type of dispersion relation that is linear along the symmetry line but quadratic in the perpendicular direction. It was originally discovered in electron systems, in which the associated quasi-particles are massless along one direction, like those in graphene, but effective-mass-like along the other. It was reported that a semi-Dirac point is associated with the topological phase transition between a semi-metallic phase and a band insulator. Very recently, the classical analogy of a semi-Dirac cone has been reported in an electromagnetic system. Here, we demonstrate that, by accidental degeneracy, two-dimensional phononic crystals consisting of square arrays of elliptical cylinders embedded in water are also able to produce the particular dispersion relation of a semi-Dirac cone in the center of the Brillouin zone. A perturbation method is used to evaluate the linear slope and to affirm that the dispersion relation is a semi-Dirac type. If the scatterers are made of rubber, in which the acoustic wave velocity is lower than that in water, the semi-Dirac dispersion can be characterized by an effective medium theory. The effective medium parameters link the semi-Dirac point to a topological transition in the iso-frequency surface of the phononic crystal, in which an open hyperbola is changed into a closed ellipse. This topological transition results in drastic change in wave manipulation. On the other hand, the theory also reveals that the phononic crystal is a double-zero-index material along the x-direction and photonic-band-edge material along the perpendicular direction (y-direction). If the scatterers are made of steel, in which the acoustic wave velocity is higher than that in water, the effective medium description fails, even though the semi-Dirac dispersion relation looks similar to that in the previous case. Therefore different wave transport behavior is expected. The semi-Dirac points in phononic crystals described in
Pairing instabilities of Dirac composite fermions
Milovanović, M. V.; Ćirić, M. Dimitrijević; Juričić, V.
2016-09-01
Recently, a Dirac (particle-hole symmetric) description of composite fermions in the half-filled Landau level (LL) was proposed [D. T. Son, Phys. Rev. X 5, 031027 (2015), 10.1103/PhysRevX.5.031027], and we study its possible consequences on BCS (Cooper) pairing of composite fermions (CFs). One of the main consequences is the existence of anisotropic states in single-layer and bilayer systems, which was previously suggested in Jeong and Park [J. S. Jeong and K. Park, Phys. Rev. B 91, 195119 (2015), 10.1103/PhysRevB.91.195119]. We argue that in the half-filled LL in the single-layer case the gapped states may sustain anisotropy, because isotropic pairings may coexist with anisotropic ones. Furthermore, anisotropic pairings with the addition of a particle-hole symmetry-breaking mass term may evolve into rotationally symmetric states, i.e., Pfaffian states of Halperin-Lee-Read (HLR) ordinary CFs. On the basis of the Dirac formalism, we argue that in the quantum Hall bilayer at total filling factor 1, with decreasing distance between the layers, weak pairing of p -wave paired CFs is gradually transformed from Dirac to ordinary, HLR-like, with a concomitant decrease in the CF number. Global characterization of low-energy spectra based on the Dirac CFs agrees well with previous calculations performed by exact diagonalization on a torus. Finally, we discuss features of the Dirac formalism when applied in this context.
Gravitationally Coupled Dirac Equation for Antimatter
Jentschura, U D
2013-01-01
The coupling of antimatter to gravity is of general interest because of conceivable cosmological consequences ("surprises") related to dark energy and the cosmological constant. Here, we revisit the derivation of the gravitationally coupled Dirac equation and find that the prefactor of a result given previously in [D.R. Brill and J.A. Wheeler, Rev. Mod. Phys., vol. 29, p. 465 (1957)] for the affine connection matrix is in need of a correction. We also discuss the conversion the curved-space Dirac equation from East-Coast to West-Coast conventions, in order to bring the gravitationally coupled Dirac equation to a form where it can easily be unified with the electromagnetic coupling as it is commonly used in modern particle physics calculations. The Dirac equation describes anti-particles as negative-energy states. We find a symmetry of the gravitationally coupled Dirac equation, which connects particle and antiparticle solutions for a general space-time metric of the Schwarzschild type and implies that particl...
Strange quark matter and quark stars with the Dyson-Schwinger quark model
Chen, H.; Wei, J.-B.; Schulze, H.-J.
2016-09-01
We calculate the equation of state of strange quark matter and the interior structure of strange quark stars in a Dyson-Schwinger quark model within rainbow or Ball-Chiu vertex approximation. We emphasize constraints on the parameter space of the model due to stability conditions of ordinary nuclear matter. Respecting these constraints, we find that the maximum mass of strange quark stars is about 1.9 solar masses, and typical radii are 9-11km. We obtain an energy release as large as 3.6 × 10^{53} erg from conversion of neutron stars into strange quark stars.
Strange quark matter and quark stars with the Dyson-Schwinger quark model
Chen, H; Schulze, H -J
2016-01-01
We calculate the equation of state of strange quark matter and the interior structure of strange quark stars in a Dyson-Schwinger quark model within rainbow or Ball-Chiu vertex approximation. We emphasize constraints on the parameter space of the model due to stability conditions of ordinary nuclear matter. Respecting these constraints, we find that the maximum mass of strange quark stars is about 1.9 solar masses, and typical radii are 9--11 km. We obtain an energy release as large as $3.6 \\times 10^{53}\\,\\text{erg}$ from conversion of neutron stars into strange quark stars.
Strange quark matter and quark stars with the Dyson-Schwinger quark model
Energy Technology Data Exchange (ETDEWEB)
Chen, H.; Wei, J.B. [China University of Geosciences, School of Mathematics and Physics, Wuhan (China); Schulze, H.J. [Universita di Catania, Dipartimento di Fisica, Catania (Italy); INFN, Sezione di Catania (Italy)
2016-09-15
We calculate the equation of state of strange quark matter and the interior structure of strange quark stars in a Dyson-Schwinger quark model within rainbow or Ball-Chiu vertex approximation. We emphasize constraints on the parameter space of the model due to stability conditions of ordinary nuclear matter. Respecting these constraints, we find that the maximum mass of strange quark stars is about 1.9 solar masses, and typical radii are 9-11 km. We obtain an energy release as large as 3.6 x 10{sup 53} erg from conversion of neutron stars into strange quark stars. (orig.)
LHCb: Monitoring the DIRAC Distribution System
Nandakumar, R; Santinelli, R
2009-01-01
DIRAC is the LHCb gateway to any computing grid infrastructure (currently supporting WLCG) and is intended to reliably run large data mining activities. The DIRAC system consists of various services (which wait to be contacted to perform actions) and agents (which carry out periodic activities) to direct jobs as required. An important part of ensuring the reliability of the infrastructure is the monitoring and logging of these DIRAC distributed systems. The monitoring is done collecting information from two sources - one is from pinging the services or by keeping track of the regular heartbeats of the agents, and the other from the analysis of the error messages generated by both agents and services and collected by the logging system. This allows us to ensure that he components are running properly and to collect useful information regarding their operations. The process status monitoring is displayed using the SLS sensor mechanism which also automatically allows one to plot various quantities and also keep ...
Two Qubits in the Dirac Representation
Rajagopal, A K
2000-01-01
A general two qubit system expressed in terms of the complete set of unit and fifteen traceless, Hermitian Dirac matrices, is shown to exhibit novel features of this system. The well-known physical interpretations associated with the relativistic Dirac equation involving the symmetry operations of time-reversal T, charge conjugation C, parity P, and their products are reinterpreted here by examining their action on the basic Bell states. The transformation properties of the Bell basis states under these symmetry operations also reveal that C is the only operator that does not mix the Bell states whereas all others do. In a similar fashion, expressing the various logic gates introduced in the subject of quantum computers in terms of the Dirac matrices shows for example, that the NOT gate is related to the product of time-reversal and parity operators.
Student Difficulties with the Dirac Delta Function
Wilcox, Bethany R
2014-01-01
The Dirac delta function is a standard mathematical tool used in multiple topical areas in the undergraduate physics curriculum. While Dirac delta functions are usually introduced in order to simplify a problem mathematically, students often struggle to manipulate and interpret them. To better understand student difficulties with the delta function at the upper-division level, we examined responses to traditional exam questions and conducted think-aloud interviews. Our analysis was guided by an analytical framework that focuses on how students activate, construct, execute, and reflect on the Dirac delta function in physics. Here, we focus on student difficulties using the delta function to express charge distributions in the context of junior-level electrostatics. Challenges included: invoking the delta function spontaneously, constructing two- and three-dimensional delta functions, integrating novel delta function expressions, and recognizing that the delta function can have units.
On Dirac Zero Modes in Hyperdiamond Model
Drissi, Lalla Btissam
2011-01-01
Using the SU(5) symmetry of the 4D hyperdiamond and results on 4D graphene, we engineer a class of 4D lattice QCD fermions whose Dirac operators have two zero modes. We show that generally the zero modes of the Dirac operator in hyperdiamond fermions are captured by a tensor {\\Omega}_{{\\mu}}^{l} with 4\\times5 complex components linking the Euclidean SO(4) vector {\\mu}; and the 5-dimensional representation of SU(5). The Bori\\c{c}i-Creutz (BC) and the Karsten-Wilzeck (KW) models as well as their Dirac zero modes are rederived as particular realizations of {\\Omega}_{{\\mu}}^{l}. Other features are also given. Keywords: Lattice QCD, Bori\\c{c}i-Creutz and Karsten-Wilzeck models, 4D hyperdiamond, 4D graphene, SU(5) Symmetry.
Quantum simulation of the Dirac equation
Energy Technology Data Exchange (ETDEWEB)
Gerritsma, Rene; Kirchmair, Gerhard; Zaehringer, Florian; Blatt, Rainer; Roos, Christian [Institut fuer Quantenoptik und Quanteninformation, 6020 Innsbruck (Austria); Solano, Enrique [Departamento de Quimica Fisica, Universidad del Pais Vasco - Euskal Herriko Unibertsitatea, Bilbao (Spain)
2010-07-01
The Dirac equation is a cornerstone in the history of physics, merging successfully quantum mechanics with special relativity, providing a natural description of the electron spin and predicting the existence of anti-matter. However, the Dirac equation also predicts some peculiar effects such as Klein's paradox and Zitterbewegung, an unexpected quivering motion of a free relativistic quantum particle first examined by Schroedinger. In this talk, we report on a proof-of-principle quantum simulation of the one-dimensional Dirac equation using a single trapped ion, which is set to behave as a free relativistic quantum particle. We measure as a function of time the particle position and study Zitterbewegung for different initial superpositions of positive and negative energy spinor states, as well as the cross-over from relativistic to nonrelativistic dynamics.
Electromagnetic Radiation From An Equilibrium Quark -Gluon Plasma System
Singh, S S; Jha, Agam K.
2006-01-01
We study the electromagnetic radiation from a hot and slightly strong interacting fireball system of quark-gluon plasma using the Boltzmann distribution function for the incoming particles and Bose-Einstein distribution for gluon in first calculation of electromagnetic radiation and Fermi-Dirac distribution for quark, antiquark and Boltzmann distribution for gluon in our second calculation. The thermal photon emission rate is found that it is infrared divergent for massless quarks which are discussed by many authors and regulate this divergence using different cut-off in the qurak mass. However we remove this divergence using the same technique of Braaten and Pisarski in the thermal mass of the system by using our model calculation in the coupling parameter. Thus the production rate of the thermal photon is found to be smoothly worked by this cut-off technique of our model. The result is found to be matched with the most of the theoretical calculations and it is in the conformity with the experimental results...
Franck-Condon principle for heavy-quark hadron decays
Llanes-Estrada, Felipe J; General, Ignacio G; Wang, Ping
2008-01-01
The Franck-Condon principle governing molecular electronic transitions is utilized to study heavy-quark hadron decays. This provides a direct assessment of the wavefunction of the parent hadron if the momentum distribution of the open-flavor decay products is measured. Model-independent results include an experimental distinction between quarkonium and exotica (hybrids, tetraquarks...), an off-plane correlator signature for tetraquarks and a direct probe of the sea quark orbital wavefunction relevant in the discussion of 3S_1 or 3P_0 decay mechanisms.
Parton distributions for the pion in a chiral quark model
Ruiz-Arriola, E
2001-01-01
Parton distributions for the pion are studied in a chiral quark model characterized by a quark propagator for which a spectral representation is assumed. Electromagnetic and chiral symmetry constraints are imposed through the relevant Ward-Takahashi identities for flavoured vertex functions. Finiteness of the theory, requires the spectral function to be non-positive definite. Straightforward calculation yields the result that the pion structure function becomes one in the chiral limit, regardless of the details of the spectral function. LO and NLO evolution provide a satisfactory description of phenomenological parameterizations of the valence distribution functions but fails to describe gluon and sea distributions.
DIRAC - The Distributed MC Production and Analysis for LHCb
Tsaregorodtsev, A
2004-01-01
DIRAC is the LHCb distributed computing grid infrastructure for MC production and analysis. Its architecture is based on a set of distributed collaborating services. The service decomposition broadly follows the ARDA project proposal, allowing for the possibility of interchanging the EGEE/ARDA and DIRAC components in the future. Some components developed outside the DIRAC project are already in use as services, for example the File Catalog developed by the AliEn project. An overview of the DIRAC architecture will be given, in particular the recent developments to support user analysis. The main design choices will be presented. One of the main design goals of DIRAC is the simplicity of installation, configuring and operation of various services. This allows all the DIRAC resources to be easily managed by a single Production Manager. The modular design of the DIRAC components allows its functionality to be easily extended to include new computing and storage elements or to handle new tasks. The DIRAC system al...
Time-dependent constrained Hamiltonian systems and Dirac brackets
Energy Technology Data Exchange (ETDEWEB)
Leon, Manuel de [Instituto de Matematicas y Fisica Fundamental, Consejo Superior de Investigaciones Cientificas, Madrid (Spain); Marrero, Juan C. [Departamento de Matematica Fundamental, Facultad de Matematicas, Universidad de La Laguna, La Laguna, Tenerife, Canary Islands (Spain); Martin de Diego, David [Departamento de Economia Aplicada Cuantitativa, Facultad de Ciencias Economicas y Empresariales, UNED, Madrid (Spain)
1996-11-07
In this paper the canonical Dirac formalism for time-dependent constrained Hamiltonian systems is globalized. A time-dependent Dirac bracket which reduces to the usual one for time-independent systems is introduced. (author)
The Dirac operator and gamma matrices for quantum Minkowski spaces
1997-01-01
Gamma matrices for quantum Minkowski spaces are found. The invariance of the corresponding Dirac operator is proven. We introduce momenta for spin 1/2 particles and get (in certain cases) formal solutions of the Dirac equation.
Ginsparg-Wilson Pions Scattering on a Staggered Sea
Chen, J W; De van Water, R S; Walker-Loud, A; Chen, Jiunn-Wei; Connell, Donal O'; Water, Ruth S. Van de; Walker-Loud, Andre
2006-01-01
In this article, we calculate isospin 2 (I=2) pion-pion scattering in chiral perturbation theory for a partially quenched, mixed action theory with Ginsparg-Wilson valence quarks and staggered sea quarks. We determine the scattering length at threshold for both 2 sea quarks and 2+1 sea quarks in the isospin limit. The scattering length, expressed in terms of the pion mass and the decay constant measured on the lattice, has no contributions from mixed valence-sea mesons. Thus, it does not depend upon the parameter, C_Mix, that appears in the chiral Lagrangian of the mixed theory. This result holds for both 2 and 2+1 flavors of sea quarks. Finally, we take the continuum limit of our mixed action results and give expressions for the scattering length in continuum 2 and 2+1 flavor partially quenched chiral perturbation theory.
Sato, T.; Segawa, Kouji; Kosaka, K.; Souma, S.; Nakayama, K.; Eto, K.; Minami, T.; Ando, Yoichi; Takahashi, T.
2011-11-01
The three-dimensional (3D) topological insulator is a novel quantum state of matter where an insulating bulk hosts a linearly dispersing surface state, which can be viewed as a sea of massless Dirac fermions protected by the time-reversal symmetry (TRS). Breaking the TRS by a magnetic order leads to the opening of a gap in the surface state, and consequently the Dirac fermions become massive. It has been proposed theoretically that such a mass acquisition is necessary to realize novel topological phenomena, but achieving a sufficiently large mass is an experimental challenge. Here we report an unexpected discovery that the surface Dirac fermions in a solid-solution system TlBi(S1-xSex)2 acquire a mass without explicitly breaking the TRS. We found that this system goes through a quantum phase transition from the topological to the non-topological phase, and, by tracing the evolution of the electronic states using the angle-resolved photoemission, we observed that the massless Dirac state in TlBiSe2 switches to a massive state before it disappears in the non-topological phase. This result suggests the existence of a condensed-matter version of the `Higgs mechanism' where particles acquire a mass through spontaneous symmetry breaking.
SPECTRAL PROPERTIES OF QUARKS IN THE QUARK-GLUON PLASMA.
Energy Technology Data Exchange (ETDEWEB)
KARSCH,F.; KITAZAWA, M.
2007-07-30
We analyze the spectral properties of the quark propagator above the critical temperature for the deconfinement phase transition in quenched lattice QCD using clover improved Wilson fermions. The bare quark mass dependence of the quark spectral function is analyzed by varying the hopping parameter {kappa} in Landau gauge. We assume a two-pole structure for the quark spectral function, which is numerically found to work quite well for any value of {kappa}. It is shown that in the chiral limit the quark spectral function has two collective modes that correspond to the normal and plasmino excitations, while it is dominated by a single-pole structure when the bare quark mass becomes large.
Spectral Properties of Quarks in the Quark-Gluon Plasma
Karsch, F
2007-01-01
We analyze the spectral properties of the quark propagator above the critical temperature for the deconfinement phase transition in quenched lattice QCD using clover improved Wilson fermions. The bare quark mass dependence of the quark spectral function is analyzed by varying the hopping parameter \\kappa in Landau gauge. We assume a two-pole structure for the quark spectral function, which is numerically found to work quite well for any value of \\kappa. It is shown that in the chiral limit the quark spectral function has two collective modes that correspond to the normal and plasmino excitations, while it is dominated by a single-pole structure when the bare quark mass becomes large.
Generalization of the Dirac’s Equation and Sea
DEFF Research Database (Denmark)
Javadi, Hossein; Forouzbakhsh, Farshid; Daei Kasmaei, Hamed
2016-01-01
. In quantum mechanics, Schrodinger equation is similar to Newton's second law in classic mechanics. Quantum mechanics is also extension of Newtonian mechanics to atomic and subatomic scales and relativistic mechanics is extension of Newtonian mechanics to high velocities near to velocity of light too....... Schrodinger equation is not a relativistic equation, because it is not invariant under Lorentz transformations. Dirac expanded The Schrodinger equation by presenting Dirac Sea and founded relativistic quantum mechanics. In this paper by reconsidering the Dirac Sea and his equation, the structure of photon...
Cloud flexibility using DIRAC interware
Fernandez Albor, Víctor; Seco Miguelez, Marcos; Fernandez Pena, Tomas; Mendez Muñoz, Victor; Saborido Silva, Juan Jose; Graciani Diaz, Ricardo
2014-06-01
Communities of different locations are running their computing jobs on dedicated infrastructures without the need to worry about software, hardware or even the site where their programs are going to be executed. Nevertheless, this usually implies that they are restricted to use certain types or versions of an Operating System because either their software needs an definite version of a system library or a specific platform is required by the collaboration to which they belong. On this scenario, if a data center wants to service software to incompatible communities, it has to split its physical resources among those communities. This splitting will inevitably lead to an underuse of resources because the data centers are bound to have periods where one or more of its subclusters are idle. It is, in this situation, where Cloud Computing provides the flexibility and reduction in computational cost that data centers are searching for. This paper describes a set of realistic tests that we ran on one of such implementations. The test comprise software from three different HEP communities (Auger, LHCb and QCD phenomelogists) and the Parsec Benchmark Suite running on one or more of three Linux flavors (SL5, Ubuntu 10.04 and Fedora 13). The implemented infrastructure has, at the cloud level, CloudStack that manages the virtual machines (VM) and the hosts on which they run, and, at the user level, the DIRAC framework along with a VM extension that will submit, monitorize and keep track of the user jobs and also requests CloudStack to start or stop the necessary VM's. In this infrastructure, the community software is distributed via the CernVM-FS, which has been proven to be a reliable and scalable software distribution system. With the resulting infrastructure, users are allowed to send their jobs transparently to the Data Center. The main purpose of this system is the creation of flexible cluster, multiplatform with an scalable method for software distribution for several
On Huygens' principle for Dirac operators associated to electromagnetic fields
Directory of Open Access Journals (Sweden)
CHALUB FABIO A.C.C.
2001-01-01
Full Text Available We study the behavior of massless Dirac particles, i.e., solutions of the Dirac equation with m = 0 in the presence of an electromagnetic field. Our main result (Theorem 1 is that for purely real or imaginary fields any Huygens type (in Hadamard's sense Dirac operators is equivalent to the free Dirac operator, equivalence given by changes of variables and multiplication (right and left by nonzero functions.
Maxwell and Dirac theories as an already unified theory
1995-01-01
In this paper we formulate Maxwell and Dirac theories as an already unified theory (in the sense of Misner and Wheeler). We introduce Dirac spinors as "Dirac square root" of the Faraday bivector, and use this in order to find a spinorial representation of Maxwell equations. Then we show that under certain circunstances this spinor equation reduces to an equation formally identical to Dirac equation. Finally we discuss certain conditions under which this equation can be really interpreted as D...
PERSAMAAN MEDAN DIRAC DALAM PENGARUH MEDAN MAGNETIK YANG SERAGAM
Directory of Open Access Journals (Sweden)
Andrias Widiantoro, Erika Rani
2012-03-01
Full Text Available Telah dilakukan perlakuan khusus terhadap persamaan gerak partikel elementer yaitu Persamaan Dirac dengan dipengaruhi oleh medan magnet eksternal yang seragam untuk mendapat solusi Persamaan Dirac dalam pengaruh medan magnetic. Penambahan pengaruh potensial magnetik terhadap momentum dan energi total suatu partikel bermuatan dalam kajian teoritis terhadap persamaan gerak yaitu persamaan Dirac telah memberikan solusi persamaan medan Dirac yang baru, dan kuantisasi kedua yang terdapat konstanta tambahan serta propagasi fermioniknya terdapat suku pengali baru.
Dirac eigenmodes at the QCD Anderson transition
Giordano, Matteo; Pittler, Ferenc; Ujfalusi, Laszlo; Varga, Imre
2014-01-01
Recently we found an Anderson-type localization-delocalization transition in the QCD Dirac spectrum at high temperature. Using spectral statistics we obtained a critical exponent compatible with that of the corresponding Anderson model. Here we study the spatial structure of the eigenmodes both in the localized and the transition region. Based on previous studies in the Anderson model, at the critical point, the eigenmodes are expected to have a scale invariant multifractal structure. We verify the scale invariance of Dirac eigenmodes at the critical point.
Search for Heavy Pointlike Dirac Monopoles
Abbott, B.; Abolins, M.; Acharya, B. S.; Adam, I.; Adams, D. L.; Adams, M.; Ahn, S.; Aihara, H.; Alves, G. A.; Amos, N.; Anderson, E. W.; Astur, R.; Baarmand, M. M.; Babukhadia, L.; Baden, A.; Balamurali, V.; Balderston, J.; Baldin, B.; Banerjee, S.; Bantly, J.; Barberis, E.; Bartlett, J. F.; Belyaev, A.; Beri, S. B.; Bertram, I.; Bezzubov, V. A.; Bhat, P. C.; Bhatnagar, V.; Bhattacharjee, M.; Biswas, N.; Blazey, G.; Blessing, S.; Bloom, P.; Boehnlein, A.; Bojko, N. I.; Borcherding, F.; Boswell, C.; Brandt, A.; Brock, R.; Bross, A.; Buchholz, D.; Burtovoi, V. S.; Butler, J. M.; Carvalho, W.; Casey, D.; Casilum, Z.; Castilla-Valdez, H.; Chakraborty, D.; Chang, S.-M.; Chekulaev, S. V.; Chen, L.-P.; Chen, W.; Choi, S.; Chopra, S.; Choudhary, B. C.; Christenson, J. H.; Chung, M.; Claes, D.; Clark, A. R.; Cobau, W. G.; Cochran, J.; Coney, L.; Cooper, W. E.; Cretsinger, C.; Cullen-Vidal, D.; Cummings, M. A.; Cutts, D.; Dahl, O. I.; Davis, K.; de, K.; del Signore, K.; Demarteau, M.; Denisov, D.; Denisov, S. P.; Diehl, H. T.; Diesburg, M.; di Loreto, G.; Draper, P.; Ducros, Y.; Dudko, L. V.; Dugad, S. R.; Edmunds, D.; Ellison, J.; Elvira, V. D.; Engelmann, R.; Eno, S.; Eppley, G.; Ermolov, P.; Eroshin, O. V.; Evdokimov, V. N.; Fahland, T.; Fatyga, M. K.; Feher, S.; Fein, D.; Ferbel, T.; Finocchiaro, G.; Fisk, H. E.; Fisyak, Y.; Flattum, E.; Forden, G. E.; Fortner, M.; Frame, K. C.; Fuess, S.; Gallas, E.; Galyaev, A. N.; Gartung, P.; Gavrilov, V.; Geld, T. L.; Genik, R. J.; Genser, K.; Gerber, C. E.; Gershtein, Y.; Gibbard, B.; Glenn, S.; Gobbi, B.; Goldschmidt, A.; Gómez, B.; Gómez, G.; Goncharov, P. I.; González Solís, J. L.; Gordon, H.; Goss, L. T.; Gounder, K.; Goussiou, A.; Graf, N.; Grannis, P. D.; Green, D. R.; Greenlee, H.; Grinstein, S.; Grudberg, P.; Grünendahl, S.; Guglielmo, G.; Guida, J. A.; Guida, J. M.; Gupta, A.; Gurzhiev, S. N.; Gutierrez, G.; Gutierrez, P.; Hadley, N. J.; Haggerty, H.; Hagopian, S.; Hagopian, V.; Hahn, K. S.; Hall, R. E.; Hanlet, P.; Hansen, S.; Hauptman, J. M.; Hedin, D.; Heinson, A. P.; Heintz, U.; Hernández-Montoya, R.; Heuring, T.; Hirosky, R.; Hobbs, J. D.; Hoeneisen, B.; Hoftun, J. S.; Hsieh, F.; Hu, Ting; Hu, Tong; Huehn, T.; Ito, A. S.; James, E.; Jaques, J.; Jerger, S. A.; Jesik, R.; Jiang, J. Z.-Y.; Joffe-Minor, T.; Johns, K.; Johnson, M.; Jonckheere, A.; Jones, M.; Jöstlein, H.; Jun, S. Y.; Jung, C. K.; Kahn, S.; Kalbfleisch, G.; Kang, J. S.; Karmanov, D.; Karmgard, D.; Kehoe, R.; Kelly, M. L.; Kim, C. L.; Kim, S. K.; Klima, B.; Klopfenstein, C.; Kohli, J. M.; Koltick, D.; Kostritskiy, A. V.; Kotcher, J.; Kotwal, A. V.; Kourlas, J.; Kozelov, A. V.; Kozlovsky, E. A.; Krane, J.; Krishnaswamy, M. R.; Krzywdzinski, S.; Kuleshov, S.; Kunori, S.; Landry, F.; Landsberg, G.; Lauer, B.; Leflat, A.; Li, H.; Li, J.; Li-Demarteau, Q. Z.; Lima, J. G.; Lincoln, D.; Linn, S. L.; Linnemann, J.; Lipton, R.; Liu, Y. C.; Lobkowicz, F.; Loken, S. C.; Lökös, S.; Lueking, L.; Lyon, A. L.; Maciel, A. K.; Madaras, R. J.; Madden, R.; Magaña-Mendoza, L.; Manankov, V.; Mani, S.; Mao, H. S.; Markeloff, R.; Marshall, T.; Martin, M. I.; Mauritz, K. M.; May, B.; Mayorov, A. A.; McCarthy, R.; McDonald, J.; McKibben, T.; McKinley, J.; McMahon, T.; Melanson, H. L.; Merkin, M.; Merritt, K. W.; Miettinen, H.; Mincer, A.; Mishra, C. S.; Mokhov, N.; Mondal, N. K.; Montgomery, H. E.; Mooney, P.; da Motta, H.; Murphy, C.; Nang, F.; Narain, M.; Narasimham, V. S.; Narayanan, A.; Neal, H. A.; Negret, J. P.; Nemethy, P.; Norman, D.; Oesch, L.; Oguri, V.; Oliveira, E.; Oltman, E.; Oshima, N.; Owen, D.; Padley, P.; Para, A.; Park, Y. M.; Partridge, R.; Parua, N.; Paterno, M.; Pawlik, B.; Perkins, J.; Peters, M.; Piegaia, R.; Piekarz, H.; Pischalnikov, Y.; Pope, B. G.; Prosper, H. B.; Protopopescu, S.; Qian, J.; Quintas, P. Z.; Raja, R.; Rajagopalan, S.; Ramirez, O.; Rasmussen, L.; Reucroft, S.; Rijssenbeek, M.; Rockwell, T.; Roco, M.; Rubinov, P.; Ruchti, R.; Rutherfoord, J.; Sánchez-Hernández, A.; Santoro, A.; Sawyer, L.; Schamberger, R. D.; Schellman, H.; Sculli, J.; Shabalina, E.; Shaffer, C.; Shankar, H. C.; Shivpuri, R. K.; Shupe, M.; Singh, H.; Singh, J. B.; Sirotenko, V.; Smart, W.; Smith, E.; Smith, R. P.; Snihur, R.; Snow, G. R.; Snow, J.; Snyder, S.; Solomon, J.; Sosebee, M.; Sotnikova, N.; Souza, M.; Spadafora, A. L.; Steinbrück, G.; Stephens, R. W.; Stevenson, M. L.; Stewart, D.; Stichelbaut, F.; Stoker, D.; Stolin, V.; Stoyanova, D. A.; Strauss, M.; Streets, K.; Strovink, M.; Sznajder, A.; Tamburello, P.; Tarazi, J.; Tartaglia, M.; Thomas, T. L.; Thompson, J.; Trippe, T. G.; Tuts, P. M.; Varelas, N.; Varnes, E. W.; Vititoe, D.; Volkov, A. A.; Vorobiev, A. P.; Wahl, H. D.; Wang, G.; Warchol, J.; Watts, G.; Wayne, M.; Weerts, H.; White, A.; White, J. T.; Wightman, J. A.; Willis, S.; Wimpenny, S. J.; Wirjawan, J. V.; Womersley, J.; Won, E.; Wood, D. R.; Xu, H.; Yamada, R.; Yamin, P.; Yang, J.; Yasuda, T.; Yepes, P.; Yoshikawa, C.; Youssef, S.; Yu, J.; Yu, Y.; Zhou, Z.; Zhu, Z. H.; Zieminska, D.; Zieminski, A.; Zverev, E. G.; Zylberstejn, A.
1998-07-01
We have searched for central production of a pair of photons with high transverse energies in pp¯ collisions at s = 1.8 TeV using 70 pb-1 of data collected with the D0 detector at the Fermilab Tevatron in 1994-1996. If they exist, virtual heavy pointlike Dirac monopoles could rescatter pairs of nearly real photons into this final state via a box diagram. We observe no excess of events above background, and set lower 95% C.L. limits of 610, 870, or 1580 GeV/c2 on the mass of a spin 0, 1/2, or 1 Dirac monopole.
Gravitational Gauge Interactions of Dirac Field
Institute of Scientific and Technical Information of China (English)
WU Ning
2004-01-01
Gravitational interactions of Dirac field are studied in this paper. Based on gauge principle, quantum gauge theory of gravity, which is perturbatively renormalizable, is formulated in the Minkowski space-time. In quantum gauge theory of gravity, gravity is treated as a kind of fundamental interactions, which is transmitted by gravitational gauge tield, and Dirac field couples to gravitational field through gravitational gauge covariant derivative. Based on this theory, we can easily explain gravitational phase effect, which has already been detected by COW experiment.
Two qubits in the Dirac representation
Rajagopal, A. K.; Rendell, R. W.
2001-08-01
The Dirac-matrix representation of a general two-qubit system is shown to exhibit quite interesting features. The relativistic symmetries of time reversal T, charge conjugation C, parity P, and their products are reinterpreted here by examining their action on the Bell states. It is shown that only C does not mix the Bell states whereas all others do. The various logic gates of quantum information theory are also expressed in terms of the Dirac matrices. For example, the NOT gate is related to the product of T and P. A two-qubit density matrix is found to be entangled if it is invariant under C.
Extended Supersymmetries and the Dirac Operator
Kirchberg, A; Wipf, A
2004-01-01
We consider supersymmetric quantum mechanical systems in arbitrary dimensions on curved spaces with nontrivial gauge fields. The square of the Dirac operator serves as Hamiltonian. We derive a relation between the number of supercharges that exist and restrictions on the geometry of the underlying spaces as well as the admissible gauge field configurations. From the superalgebra with two or more real supercharges we infer the existence of integrability conditions and obtain a corresponding superpotential. This potential can be used to deform the supercharges and to determine zero modes of the Dirac operator. The general results are applied to the Kahler spaces CP^n.
Parametrization of Fully Dressed Quark Propagator
Institute of Scientific and Technical Information of China (English)
MA Wei-Xing; ZHU Ji-Zhen; ZHOU Li-Juan; SHEN Peng-Nian; HU Zhao-Hui
2005-01-01
Based on an extensive study of the Dyson-Schwinger equations for a fully dressed quark propagator in the "rainbow" approximation, a parametrized form of the quark propagator is suggested. The corresponding quark selfform of the quark propagator proposed in this work describes a confining quark propagation, and is quite convenient to be used in any numerical calculations.
The Multimedia Project Quarked!
Bean, Alice
2011-01-01
Can exposure to fundamental ideas about the nature of matter help motivate children in math and science and support the development of their understanding of these ideas later? Physicists, designers, and museum educators at the University of Kansas created the Quarked!(tm) Adventures in the subatomic Universe project to provide an opportunity for youth to explore the subatomic world in a fun and user friendly way. The project components include a website (located at http://www.quarked.org) and hands-on education programs. These are described and assessment results are presented. Questions addressed include the following. Can you engage elementary and middle school aged children with concepts related to particle physics? Can young children make sense of something they can't directly see? Do teachers think the material is relevant to their students?
Riordan, M
1992-05-29
Quarks are widely recognized today as being among the elementary particles of which matter is composed. The key evidence for their existence came from a series of inelastic electron-nucleon scattering experiments conducted between 1967 and 1973 at the Stanford Linear Accelerator Center. Other theoretical and experimental advances of the 1970s confirmed this discovery, leading to the present standard model of elementary particle physics.
Melting Hadrons, Boiling Quarks
Rafelski, Johann
2015-01-01
In the context of the Hagedorn temperature half-centenary I describe our understanding of the hot phases of hadronic matter both below and above the Hagedorn temperature. The first part of the review addresses many frequently posed questions about properties of hadronic matter in different phases, phase transition and the exploration of quark-gluon plasma (QGP). The historical context of the discovery of QGP is shown and the role of strangeness and strange antibaryon signature of QGP illustra...
Kane, Gordon L.; Perry, Malcolm J.
2015-03-01
We are used to thinking of quarks as fundamental particles in the same way we think of the electron, or gauge bosons, neutrinos, leptons. In strong theory, these objects are unified with gravitation and the physics of spacetime into what is hoped to be an ultimate theory, string/M theory. The string/M theory paradigm completely changes the way we think of the socalled elementary particles in quantum field theory.
Santopinto, E
2015-01-01
In this contribution, we briefly discuss the results for charmonium and bottomonium spectra with self-energy corrections in the unquenched quark model, due to the coupling to the meson-meson continuum. The UQM formalism can be extended to include also the effects of hybrid mesons, i.e. hybrid loops. Finally, we discuss the results of a calculation of hybrid mesons spectrum in Coulomb Gauge QCD.
Top quark pair production and top quark properties at CDF
Energy Technology Data Exchange (ETDEWEB)
Moon, Chang-Seong [INFN, Pisa
2016-06-02
We present the most recent measurements of top quark pairs production and top quark properties in proton-antiproton collisions with center-of-mass energy of 1.96 TeV using CDF II detector at the Tevatron. The combination of top pair production cross section measurements and the direct measurement of top quark width are reported. The test of Standard Model predictions for top quark decaying into $b$-quarks, performed by measuring the ratio $R$ between the top quark branching fraction to $b$-quark and the branching fraction to any type of down quark is shown. The extraction of the CKM matrix element $|V_{tb}|$ from the ratio $R$ is discussed. We also present the latest measurements on the forward-backward asymmetry ($A_{FB}$) in top anti-top quark production. With the full CDF Run II data set, the measurements are performed in top anti-top decaying to final states that contain one or two charged leptons (electrons or muons). In addition, we combine the results of the leptonic forward-backward asymmetry in $t\\bar t$ system between the two final states. All the results show deviations from the next-to-leading order (NLO) standard model (SM) calculation.
Dirac oscillators and quasi-exactly solvable operators
Brihaye, Y
2005-01-01
The Dirac equation is considered in the background of potentials of several types, namely scalar and vector-potentials as well as "Dirac-oscillator" potential or some of its generalisations. We investigate the radial Dirac equation within a quite general spherically symmetric form for these potentials and we analyse some exactly and quasi exactly solvable properties of the underlying matricial linear operators.
Interconnection of Dirac structures via kernel/image representation
Iftime, Orest V.; Sandovici, Adrian
2011-01-01
Dirac structures are used to mathematically formalize the power-conserving interconnection structure of physical systems. For finite-dimensional systems several representations are available and it is known that the composition (or interconnection) of two Dirac structures is again a Dirac structure.
Nayak, Tapan; Sarkar, Sourav
2014-01-01
At extremely high temperatures and densities, protons and neutrons may dissolve into a "soup" of quarks and gluons, called the Quark-Gluon Plasma (QGP). For a few microseconds, shortly after the Big Bang, the Universe was filled with the QGP matter. The search and study of Quark-Gluon Plasma (QGP) is one of the most fundamental research topics of our times. The QGP matter has been probed by colliding heavy ions at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory, New York and the Large Hadron Collider at CERN, Geneva. By colliding heavy-ions at a speed close to that of light, scientists aim to obtain - albeit over a tiny volume of the size of a nucleus and for an infinitesimally short instant - a QGP state. This QGP state can be observed by dedicated experiments, as it reverts to hadronic matter through expansion and cooling. This volume presents some of the current theoretical and experimental understandings in the field of QGP.
Validity of Parametrized Quark Propagator
Institute of Scientific and Technical Information of China (English)
ZHUJi-Zhen; ZHOULi-Juan; MAWei-Xing
2005-01-01
Based on an extensively study of the Dyson-Schwinger equations for a fully dressed quark propagator in the “rainbow”approximation, a parametrized fully dressed quark propagator is proposed in this paper. The parametrized propagator describes a confining quark propagator in hadron since it is analytic everywhere in complex p2-plane and has no Lemmann representation. The validity of the new propagator is discussed by comparing its predictions on selfenergy functions A/(p2), Bl(p2) and effective mass M$(p2) of quark with flavor f to their corresponding theoretical results produced by Dyson-Schwinger equations. Our comparison shows that the parametrized quark propagator is a good approximation to the fully dressed quark propagator given by the solutions of Dyson-Schwinger equations in the rainbow approximation and is convenient to use in any theoretical calculations.
Validity of Parametrized Quark Propagator
Institute of Scientific and Technical Information of China (English)
ZHU Ji-Zhen; ZHOU Li-Juan; MA Wei-Xing
2005-01-01
Based on an extensively study of the Dyson-Schwinger equations for a fully dressed quark propagator in the "rainbow" approximation, a parametrized fully dressed quark propagator is proposed in this paper. The parametrized propagator describes a confining quark propagator in hadron since it is analytic everywhere in complex p2-plane and has no Lemmann representation. The validity of the new propagator is discussed by comparing its predictions on selfenergy functions Af(p2), Bf(p2) and effective mass Mf(p2) of quark with flavor f to their corresponding theoretical results produced by Dyson-Schwinger equations. Our comparison shows that the parametrized quark propagator is a good approximation to the fully dressed quark propagator given by the solutions of Dyson-Schwinger equations in the rainbow approximation and is convenient to use in any theoretical calculations.
String worldsheet for accelerating quark
Hubeny, Veronika E.; Semenoff, Gordon W.
2015-10-01
We consider the AdS bulk dual to an external massive quark in SYM following an arbitrary trajectory on Minkowski background. While a purely outgoing boundary condition on the gluonic field allows one to express the corresponding string worldsheet in a closed form, the setup has curious consequences. In particular, we argue that any quark whose trajectory on flat spacetime approaches that of a light ray in the remote past (as happens e.g. in the case of uniform acceleration) must necessarily be accompanied by an anti-quark. This is puzzling from the field theory standpoint, since one would expect that a sole quark following any timelike trajectory should be allowed. We explain the resolution in terms of boundary and initial conditions. We analyze the configuration in global AdS, which naturally suggests a modification to the boundary conditions allowing for a single accelerated quark without accompanying anti-quark. We contrast this resolution with earlier proposals.
Excitation rates of heavy quarks
Energy Technology Data Exchange (ETDEWEB)
Canal, C.A.G.; Santangelo, E.M.; Ducati, M.B.G.
1985-06-01
We obtain the production rates for c, b, and t quarks in deep-inelastic neutrino- (antineutrino-) nucleon interactions, in the standard six-quark model with left-handed couplings. The results are obtained with the most recent mixing parameters and we include a comparison between quark parametrizations. The excitations are calculated separately for each flavor, allowing the understanding of the role of threshold effects when considered through different rescaling variables.
Quark matter or new particles?
Michel, F. Curtis
1988-01-01
It has been argued that compression of nuclear matter to somewhat higher densities may lead to the formation of stable quark matter. A plausible alternative, which leads to radically new astrophysical scenarios, is that the stability of quark matter simply represents the stability of new particles compounded of quarks. A specific example is the SU(3)-symmetric version of the alpha particle, composed of spin-zero pairs of each of the baryon octet (an 'octet' particle).
Quark matter or new particles?
Michel, F. Curtis
1988-01-01
It has been argued that compression of nuclear matter to somewhat higher densities may lead to the formation of stable quark matter. A plausible alternative, which leads to radically new astrophysical scenarios, is that the stability of quark matter simply represents the stability of new particles compounded of quarks. A specific example is the SU(3)-symmetric version of the alpha particle, composed of spin-zero pairs of each of the baryon octet (an 'octet' particle).
Static quark-antiquark potential
Energy Technology Data Exchange (ETDEWEB)
Deo, B.B.; Barik, B.K.
1983-01-01
A heavy-quark--antiquark potential is suggested which connects asymptotic freedom and quark confinement in a unified manner by formal methods of field theory using some plausible assumptions. The potential has only one additional adjustable parameter B which is proportional to (M/sub q//m/sub q/), where M/sub q/ and m/sub q/ are the constituent and current quark masses, respectively.
Phenomenology of heavy quark systems
Energy Technology Data Exchange (ETDEWEB)
Gilman, F.J.
1987-03-01
The spectroscopy of heavy quark systems is examined with regards to spin independent and spin dependent potentials. It is shown that a qualitative picture exists of the spin-independent forces, and that a semi-quantitative understanding exists for the spin-dependent effects. A brief review is then given of the subject of the decays of hadrons containing heavy quarks, including weak decays at the quark level, and describing corrections to the spectator model. (LEW)
Exotic Signals of Vectorlike Quarks
Energy Technology Data Exchange (ETDEWEB)
Dobrescu, Bogdan A. [Fermilab; Yu, Felix [U. Mainz, PRISMA
2016-12-06
Vectorlike fermions are an important target for hadron collider searches. We show that the vectorlike quarks may predominantly decay via higher-dimensional operators into a quark plus a couple of other Standard Model fermions. Pair production of vectorlike quarks of charge 2/3 at the LHC would then lead to a variety of possible final states, including $t\\bar t + 4\\tau$, $t\\bar b\
Lu, Wei; Liu, Xuefeng; Lu, Hong; Li, Caizhen; Lai, Jiawei; Zhao, Chuan; Tian, Ye; Liao, Zhimin; Jia, Shuang; Sun, Dong
2016-01-01
Three dimensional (3D) Dirac semimetal exhibiting ultrahigh mobility has recently attracted enormous research interests as 3D analogues of graphene. From the prospects of future application toward electronic/optoelectronic devices with extreme performance, it is crucial to understand the relaxation dynamics of photo-excited carriers and their coupling with lattice. In this work, we report ultrafast transient reflection measurements of photo-excited carrier dynamics in cadmium arsenide (Cd3As2), which is among the most stable Dirac semimetals that have been confirmed experimentally. With low energy probe photon of 0.3 eV, photo-excited Dirac Fermions dynamics closing to Dirac point are probed. Through transient reflection measurements on bulk and nanoplate samples that have different doping intensities, and systematic probe wavelength, pump power and lattice temperature dependent measurements, the dynamical evolution of carrier distributions can be retrieved qualitatively using a two-temperature model. The pho...
Antinori, Federico; Bass, Steffen A.; Bellwied, Rene; Ullrich, Thomas; Velkovska, Julia; Wiedemann, Urs
2005-04-01
Why another conference devoted to ultra-relativistic heavy-ion physics? As we looked around the landscape of the existing international conferences and workshops, we realized that there was not a single one tailored to the people who are most directly involved with the actual research work: students, post-docs, and junior faculty/research scientists. Of course there are schools, but that was not what we had in mind. We wanted a meeting where young researchers could come together to discuss in depth the physics that they are working on without any hindrance. The major conferences have very limited time for discussions which is often shared amongst the most established. This leaves little room for young people to ask their questions and to get the detailed feedback which they deserve and which satisfies their curiosity. A discussion-driven workshop, centering on those without whom there will be no future—that seemed like what was needed. And thus the Hot Quarks workshop was born. The aim of Hot Quarks was to enhance the direct exchange of scientific information among the younger members of the community, from both experiment and theory. Participation was by invitation only in order to emphasize the contributions from junior researchers. This approach makes the workshop unique among the many forums in the field. For young scientists it represented an opportunity for exposure that they would not have had in one of the major conferences. The hope is that this meeting has helped to stimulate the next generation of scientists in our field and, at the same time, strengthened their sense of community. It all came together from 18 24 July 2004, when the 77 participants met at The Inn at Snakedance in the Taos Ski Valley, New Mexico, USA, for the first Hot Quarks workshop. Photograph Participants gather in the sunshine at the foot of the Taos Ski Valley chairlift. By all accounts, Hot Quarks 2004 was a great success. Every participant had the opportunity to present her or
Top Quark Current Experimental Status
Juste, A
2006-01-01
Ten years after its discovery at the Tevatron collider, we still know little about the top quark. Its large mass suggests it may play a key role in the mechanism of Electroweak Symmetry Breaking (EWSB), or open a window of sensitivity to new physics related to EWSB and preferentially coupled to it. To determine whether this is the case, precision measurements of top quark properties are necessary. The high statistics samples being collected by the Tevatron experiments during Run II start to incisively probe the top quark sector. This report summarizes the experimental status of the top quark, focusing in particular on the recent measurements from the Tevatron.
Quark forces from hadronic spectroscopy.
Pirjol, Dan; Schat, Carlos
2009-04-17
We consider the implications of the most general two-body quark-quark interaction Hamiltonian for the spin-flavor structure of the negative parity L = 1 excited baryons. Assuming the most general two-body quark interaction Hamiltonian, we derive two correlations among the masses and mixing angles of these states, which constrain the mixing angles, and can be used to test for the presence of three-body quark interactions. We find that the pure gluon-exchange model is disfavored by data, independently of any assumptions about hadronic wave functions.
K -> pi l nu form factors with staggered quarks
Gamiz, E; El-Khadra, A X; Kronfeld, A S; Mackenzie, P B; Simone, J
2011-01-01
We report on the status of the Fermilab-MILC calculation of the form factor f_+^{K pi}(0), needed to extract the CKM matrix element |V_{us}| from experimental data on K semileptonic decays. The HISQ formulation is used in the simulations for the valence quarks, while the sea quarks are simulated with the asqtad action (MILC N_f=2+1 configurations). We discuss the general methodology of the calculation, including the use of twisted boundary conditions to get values of the momentum transfer close to zero and the different techniques applied for the correlators fits. We present initial results for lattice spacings a=0.12fm and a=0.09fm, and several choices of the light quark masses.
LHCb: DIRAC A community grid solution
Tsaregorodtsev, A
2007-01-01
The DIRAC project began as a solution for the LHCb experiment at CERN to carry out massive Monte Carlo simulation and data processing on various distributed computing resources. Now it is evolving to a complete Grid solution for community of users such as LHCb.
The Dirac-Electron Vacuum Wave
Directory of Open Access Journals (Sweden)
Daywitt W. C.
2016-07-01
Full Text Available This paper argues that the Dirac equation can be interpreted as an interaction between the electron core and the Planck vacuum state, where the positive and negative solutions represent respectively the dynamics of the electron core and a vacuum wave propagating within the vacuum state. Results show that the nonrelativistic positive solution reduces to the Schrödinger wave equation
Strongly interacting two-dimensional Dirac fermions
Lim, L.K.; Lazarides, A.; Hemmerich, Andreas; de Morais Smith, C.
2009-01-01
We show how strongly interacting two-dimensional Dirac fermions can be realized with ultracold atoms in a two-dimensional optical square lattice with an experimentally realistic, inherent gauge field, which breaks time reversal and inversion symmetries. We find remarkable phenomena in a temperature
Quantum simulation of the Dirac equation.
Gerritsma, R; Kirchmair, G; Zähringer, F; Solano, E; Blatt, R; Roos, C F
2010-01-07
The Dirac equation successfully merges quantum mechanics with special relativity. It provides a natural description of the electron spin, predicts the existence of antimatter and is able to reproduce accurately the spectrum of the hydrogen atom. The realm of the Dirac equation-relativistic quantum mechanics-is considered to be the natural transition to quantum field theory. However, the Dirac equation also predicts some peculiar effects, such as Klein's paradox and 'Zitterbewegung', an unexpected quivering motion of a free relativistic quantum particle. These and other predicted phenomena are key fundamental examples for understanding relativistic quantum effects, but are difficult to observe in real particles. In recent years, there has been increased interest in simulations of relativistic quantum effects using different physical set-ups, in which parameter tunability allows access to different physical regimes. Here we perform a proof-of-principle quantum simulation of the one-dimensional Dirac equation using a single trapped ion set to behave as a free relativistic quantum particle. We measure the particle position as a function of time and study Zitterbewegung for different initial superpositions of positive- and negative-energy spinor states, as well as the crossover from relativistic to non-relativistic dynamics. The high level of control of trapped-ion experimental parameters makes it possible to simulate textbook examples of relativistic quantum physics.
Scarring of Dirac fermions in chaotic billiards.
Ni, Xuan; Huang, Liang; Lai, Ying-Cheng; Grebogi, Celso
2012-07-01
Scarring in quantum systems with classical chaotic dynamics is one of the most remarkable phenomena in modern physics. Previous works were concerned mostly with nonrelativistic quantum systems described by the Schrödinger equation. The question remains outstanding of whether truly relativistic quantum particles that obey the Dirac equation can scar. A significant challenge is the lack of a general method for solving the Dirac equation in closed domains of arbitrary shape. In this paper, we develop a numerical framework for obtaining complete eigensolutions of massless fermions in general two-dimensional confining geometries. The key ingredients of our method are the proper handling of the boundary conditions and an efficient discretization scheme that casts the original equation in a matrix representation. The method is validated by (1) comparing the numerical solutions to analytic results for a geometrically simple confinement and (2) verifying that the calculated energy level-spacing statistics of integrable and chaotic geometries agree with the known results. Solutions of the Dirac equation in a number of representative chaotic geometries establish firmly the existence of scarring of Dirac fermions.
Consequences of Dirac Theory of the Positron
Heisenberg, W K
1936-01-01
According to Dirac's theory of the positron, an electromagnetic field tends to create pairs of particles which leads to a change of Maxwell's equations in the vacuum. These changes are calculated in the special case that no real electrons or positrons are present and the field varies little over a Compton wavelength.
Building Atomic Nuclei with the Dirac Equation
Serot, Brian D.
2003-01-01
The relevance of the Dirac equation for computations of nuclear structure is motivated and discussed. Quantitatively successful results for medium- and heavy-mass nuclei are described, and modern ideas of effective field theory and density functional theory are used to justify them.
Poisson Geometry from a Dirac perspective
Meinrenken, Eckhard
2016-01-01
We present proofs of classical results in Poisson geometry using techniques from Dirac geometry. This article is based on mini-courses at the Poisson summer school in Geneva, June 2016, and at the workshop "Quantum Groups and Gravity" at the University of Waterloo, April 2016.
A two-dimensional Dirac fermion microscope
DEFF Research Database (Denmark)
Bøggild, Peter; Caridad, Jose; Stampfer, Christoph
2017-01-01
in the solid state. Here we provide a perspective view on how a two-dimensional (2D) Dirac fermion-based microscope can be realistically implemented and operated, using graphene as a vacuum chamber for ballistic electrons. We use semiclassical simulations to propose concrete architectures and design rules of 2...
Cold quark matter in compact stars
Energy Technology Data Exchange (ETDEWEB)
Franzon, B.; Fogaca, D. A.; Navarra, F. S. [Instituto de Fisica, Universidade de Sao Paulo Rua do Matao, Travessa R, 187, 05508-090 Sao Paulo, SP (Brazil); Horvath, J. E. [Instituto de Astronomia, Geofisica e Ciencias Atmosfericas, Universidade de Sao Paulo, Rua do Matao, 1226, 05508-090, Sao Paulo, SP (Brazil)
2013-03-25
We used an equation of state for the cold quark matter to the study of properties of quark stars. We also discuss the absolute stability of quark matter and compute the mass-radius relation for self-bound stars.
The GridPP DIRAC project - DIRAC for non-LHC communities
Bauer, D; Currie, R; Fayer, S; Huffman, A; Martyniak, J; Rand, D; Richards, A
2015-01-01
The GridPP consortium in the UK is currently testing a multi-VO DIRAC service aimed at non-LHC VOs. These VOs (Virtual Organisations) are typically small and generally do not have a dedicated computing support post. The majority of these represent particle physics experiments (e.g. NA62 and COMET), although the scope of the DIRAC service is not limited to this field. A few VOs have designed bespoke tools around the EMI-WMS & LFC, while others have so far eschewed distributed resources as they perceive the overhead for accessing them to be too high. The aim of the GridPP DIRAC project is to provide an easily adaptable toolkit for such VOs in order to lower the threshold for access to distributed resources such as Grid and cloud computing. As well as hosting a centrally run DIRAC service, we will also publish our changes and additions to the upstream DIRAC codebase under an open-source license. We report on the current status of this project and show increasing adoption of DIRAC within the non-LHC communiti...
The GridPP DIRAC project - DIRAC for non-LHC communities
Bauer, D.; Colling, D.; Currie, R.; Fayer, S.; Huffman, A.; Martyniak, J.; Rand, D.; Richards, A.
2015-12-01
The GridPP consortium in the UK is currently testing a multi-VO DIRAC service aimed at non-LHC VOs. These VOs (Virtual Organisations) are typically small and generally do not have a dedicated computing support post. The majority of these represent particle physics experiments (e.g. NA62 and COMET), although the scope of the DIRAC service is not limited to this field. A few VOs have designed bespoke tools around the EMI-WMS & LFC, while others have so far eschewed distributed resources as they perceive the overhead for accessing them to be too high. The aim of the GridPP DIRAC project is to provide an easily adaptable toolkit for such VOs in order to lower the threshold for access to distributed resources such as Grid and cloud computing. As well as hosting a centrally run DIRAC service, we will also publish our changes and additions to the upstream DIRAC codebase under an open-source license. We report on the current status of this project and show increasing adoption of DIRAC within the non-LHC communities.
The Rare Two-Dimensional Materials with Dirac Cones
Wang, Jinying; Deng, Shibin; Liu, Zhongfan; Liu, Zhirong
2014-01-01
Inspired by the great development of graphene, more and more works have been conducted to seek new two-dimensional (2D) materials with Dirac cones. Although 2D Dirac materials possess many novel properties and physics, they are rare compared with the numerous 2D materials. To provide explanation for the rarity of 2D Dirac materials as well as clues in searching for new Dirac systems, here we review the recent theoretical aspects of various 2D Dirac materials, including graphene, silicene, ger...
Wigner function for the Dirac oscillator in spinor space
Institute of Scientific and Technical Information of China (English)
MA Kai; WANG Jian-Hua; YUAN Yi
2011-01-01
The Wigner function for the Dirac oscillator in spinor space is studied in this paper.Firstly,since the Dirac equation is described as a matrix equation in phase space,it is necessary to define the Wigner function as a matrix function in spinor space.Secondly,the matrix form of the Wigner function is proven to support the Dirac equation.Thirdly,by solving the Dirac equation,energy levels and the Wigner function for the Dirac oscillator in spinor space are obtained.
The Discovery of the Top Quark
Sinervo, P.K.
1995-12-01
The top quark and the Higgs boson are the heaviest elementary particles predicted by the standard model. The four lightest quark flavours, the up, down, strange and charm quarks, were well-established by the mid-1970's. The discovery in 1977 of the {Tau} resonances, a new family of massive hadrons, required the introduction of the fifth quark flavour. Experimental and theoretical studies have indicated that this quark also has a heavier partner, the top quark.
Quark and Gluon Relaxation in Quark-Gluon Plasmas
Heiselberg, H.; Pethick, C. J.
1993-01-01
The quasiparticle decay rates for quarks and gluons in quark-gluon plasmas are calculated by solving the kinetic equation. Introducing an infrared cutoff to allow for nonperturbative effects, we evaluate the quasiparticle lifetime at momenta greater than the inverse Debye screening length to leading order in the coupling constant.
Quark and Gluon Relaxation in Quark-Gluon Plasmas
Heiselberg, H.; Pethick, C. J.
1993-01-01
The quasiparticle decay rates for quarks and gluons in quark-gluon plasmas are calculated by solving the kinetic equation. Introducing an infrared cutoff to allow for nonperturbative effects, we evaluate the quasiparticle lifetime at momenta greater than the inverse Debye screening length to leading order in the coupling constant.
Lattice simulations with $N_f=2+1$ improved Wilson fermions at a fixed strange quark mass
Bali, Gunnar S; Simeth, Jakob; Söldner, Wolfgang
2016-01-01
The explicit breaking of chiral symmetry of the Wilson fermion action results in additive quark mass renormalization. Moreover, flavour singlet and non-singlet scalar currents acquire different renormalization constants with respect to continuum regularization schemes. This complicates keeping the renormalized strange quark mass fixed when varying the light quark mass in simulations with $N_f=2+1$ sea quark flavours. Here we present and validate our strategy within the CLS (Coordinated Lattice Simulations) effort to achieve this in simulations with non-perturbatively order-$a$ improved Wilson fermions. We also determine various combinations of renormalization constants and improvement coefficients.
Dirac dynamical resonance states around Schwarzschild black holes
Zhou, Xiang-Nan; Yang, Ke; Liu, Yu-Xiao
2013-01-01
Recently, a novel kind of scalar wigs around Schwarzschild black holes---scalar dynamical resonance states were introduced in [Phys. Rev. D 84, 083008 (2011)] and [Phys. Rev. Lett. 109, 081102 (2012)]. In this paper, we investigate the existence and evolution of Dirac dynamical resonance states. First we look for stationary resonance states of a Dirac field around a Schwarzchild black hole by using the Schrodinger-like equations reduced from the Dirac equation in Schwarzschild spacetime. Then Dirac pseudo-stationary configurations are constructed from the stationary resonance states. We use these configurations as initial data and investigate their numerical evolutions and energy decay. These dynamical solutions are the so-called "Dirac dynamical resonance states". It is found that the energy of the Dirac dynamical resonance states shows an exponential decay. The decay rate of energy is affected by the resonant frequency, the mass of Dirac field, the total angular momentum, and the spin-orbit interaction. In ...
Kurkela, Aleksi; Vuorinen, Aleksi
2016-07-22
We generalize the state-of-the-art perturbative equation of state of cold quark matter to nonzero temperatures, needed in the description of neutron star mergers and core collapse processes. The new result is accurate to O(g^{5}) in the gauge coupling, and is based on a novel framework for dealing with the infrared sensitive soft field modes of the theory. The zero Matsubara mode sector is treated via a dimensionally reduced effective theory, while the soft nonzero modes are resummed using the hard thermal loop approximation. This combination of known effective descriptions offers unprecedented access to small but nonzero temperatures, both in and out of beta equilibrium.
Kurkela, Aleksi
2016-01-01
We generalize the state-of-the-art perturbative Equation of State of cold quark matter to nonzero temperatures, needed in the description of neutron star mergers and core collapse processes. The new result is accurate to order g^5 in the gauge coupling, and is based on a novel framework for dealing with the infrared sensitive soft field modes of the theory. The zero Matsubara mode sector is treated using a dimensionally reduced effective theory, while the soft non-zero modes are resummed using the Hard Thermal Loop approximation. This combination of known effective descriptions offers unprecedented access to small but nonzero temperatures, both in and out of beta equilibrium.
Anderson's absolute objects and constant timelike vector hidden in Dirac matrices
2001-01-01
Anderson's theorem asserting, that symmetry of dynamic equations written in the relativisitically covariant form is determined by symmetry of its absolute objects, is applied to the free Dirac equation. Dirac matrices are the only absolute objects of the Dirac equation. There are two ways of the Dirac matrices transformation: (1) Dirac matrices form a 4-vector and wave function is a scalar, (2) Dirac matrices are scalars and the wave function is a spinor. In the first case the Dirac equation ...
Complete Monopole Dominance of the Static Quark Potential
Cundy, Nigel
2016-01-01
In earlier work, we used a gauge independent Abelian Decomposition to show that Abelian degrees of freedom are wholly responsible for the static quark potential. The restricted Abelian field can be split into two terms, a Maxwell term and a $\\theta$ (Dirac) term. The $\\theta$ term's contribution to the string tension can be analysed theoretically and numerically, and arises because of the existence of a certain type of monopole. While the Abelian field can be constructed without gauge fixing, its two component parts are gauge-dependent, with a gauge transformation moving the topological features from one part to another. This allows us to isolate and identify the topological objects responsible for confinement by constructing a gauge where the $\\theta$ term wholly accounts for the string tension. We confirm the presence of these monopoles in lattice simulations of SU(2) Yang-Mills theory.
Energy Technology Data Exchange (ETDEWEB)
Déliot, Frédéric [IRFU, Saclay; Hadley, Nicholas [Maryland U., College Park; Parke, Stephen [Fermilab; Schwarz, Tom [Michigan U.
2014-10-01
The top quark is the heaviest known elementary particle, and it is often seen as a window to search for new physics processes in particle physics. A large program to study the top-quark properties has been performed both at the Tevatron and LHC colliders by the D0, CDF, ATLAS and CMS experiments. The most recent results are discussed in this article.
Heavy quark spectroscopy at LHCb
INSPIRE-00165164
2015-01-01
The analysis of $3.0 fb^{-1}$ of proton-proton collisions collected with the LHCb detector has yielded a broad range of results in spectroscopy of conventional and exotic hadrons with heavy quark(s) inside. We review the LHCb results which have been obtained over the last year.
Broniowski, Wojciech; Rybczynski, Maciej
2016-01-01
We review the results of the wounded quark model, with a stress on eccentricity observables in small systems. A new element is a presentation of symmetric cumulants for the elliptic and triangular flow correlations, obtained in the wounded-quark approach.
πK scattering in full QCD with domain-wall valence quarks
Beane, Silas R.; Bedaque, Paulo F.; Luu, Thomas C.; Orginos, Kostas; Pallante, Elisabetta; Parreño, Assumpta; Savage, Martin J.
2006-01-01
We calculate the π+K+ scattering length in fully-dynamical lattice QCD with domain-wall valence quarks on MILC lattices with rooted staggered sea-quarks at a lattice spacing of b = 0.125 fm, lattice spatial size of L = 2.5 fm and at pion masses of mπ ~ 290, 350, 490 and 600 MeV. The lattice data, an
Nucleon structure functions and longitudinal spin asymmetries in the chiral quark constituent model
Dahiya, Harleen
2016-01-01
We have analysed the phenomenological dependence of the spin independent ($F_1^{p,n}$ and $F_2^{p,n}$) and the spin dependent ($g_1^{p,n}$) structure functions of the nucleon on the the Bjorken scaling variable $x$ using the unpolarized distribution functions of the quarks $q(x)$ and the polarized distribution functions of the quarks $\\Delta q(x)$ respectively. The chiral constituent quark model ($\\chi$CQM), which is known to provide a satisfactory explanation of the proton spin crisis and related issues in the nonperturbative regime, has been used to compute explicitly the valence and sea quark flavor distribution functions of $p$ and $n$. In light of the improved precision of the world data, the $p$ and $n$ longitudinal spin asymmetries ($A_1^p(x)$ and $A_1^n(x)$) have been calculated. The implication of the presence of the sea quarks has been discussed for ratio of polarized to unpolarized quark distribution functions for up and down quarks in the $p$ and $n$ $\\frac{\\Delta u^p(x)}{u^p(x)}$, $\\frac{\\Delta d...
Drell-Yan lepton pair production at LHC and TMD quark densities of the proton
Energy Technology Data Exchange (ETDEWEB)
Baranov, S.P. [P.N. Lebedev Institute of Physics, Moscow (Russian Federation); Lipatov, A.V. [Lomonosov Moscow State Univ. (Russian Federation). Skobeltsyn Inst. of Nuclear Physics; Joint Institute for Nuclear Research, Dubna (Russian Federation); Zotov, N.P. [Lomonosov Moscow State Univ. (Russian Federation). Skobeltsyn Inst. of Nuclear Physics
2014-03-15
We use the TMD quark densities of the proton to investigate unpolarized Drell-Yan lepton pair production in proton-proton collisions at the LHC energies. We investigate the case where the gluon-to-quark splitting occurs at the last evolution step and calculate the TMD sea quark density as a convolution of the CCFM-evolved gluon distribution and the TMD gluon-to-quark splitting function which contains all single logarithmic small-x corrections to the sea quark evolution for any order of perturbation theory. Based on the O(α) production amplitude q{sup *} + anti q{sup *}→Z/γ{sup *}→l{sup +} + l{sup -} which calculated according to the reggeized quark approach, we analyze the distributions on the dilepton invariant mass, transverse momentum and rapidity as well as the specific angular correlations between the produced leptons as measured by the CMS, ATLAS and LHCb collaborations. We argue that these measurements impose stringent constraints on the TMD quark distributions of the proton.
Low lying baryon spectrum with N{sub f}=2+1+1 dynamical twisted quarks
Energy Technology Data Exchange (ETDEWEB)
Drach, Vincent; Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Carbonell, Jaume; Papinutto, Mauro [UJF, CNRS/IN2P3, INPG (France). Lab. de Physique Subatomique et de Cosmologie; Alexandrou, Constantia [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics
2010-12-15
We present first results on the octet and decuplet strange baryon spectrum with N{sub f}=2+1+1 twisted mass quarks. We use an Osterwalder Seiler valence strange quark with a mass tuned to the kaon and compare the results with those obtained in the unitary setup. This comparison allows to perform a first study of the lattice artefacts introduced by the mixed action approach. We investigate the effect of the strange and charm quarks in the sea by using two lattice spacings and comparing with preceding N{sub f}=2 twisted mass fermion calculations. (orig.)
Low lying baryon spectrum with $N_f = 2+1+1$ dynamical twisted quarks
Drach, Vincent; Carbonell, Jaume; Papinutto, Mauro; Alexandrou, Constantia
2010-01-01
We present first results on the octet and decuplet strange baryon spectrum with $N_f=2+1+1$ twisted mass quarks. We use an Osterwalder Seiler valence strange quark with a mass tuned to the kaon and compare the results with those obtained in the unitary setup. This comparison allows to perform a first study of the lattice artefacts introduced by the mixed action approach. We investigate the effect of the strange and charm quarks in the sea by using two lattice spacings and comparing with preceding $N_f = 2$ twisted mass fermion calculations.
Hansen, Frederik F.; Langaeble, Kasper; Mann, Robert B.; Sannino, Francesco; Steele, Tom G.; Wang, Zhi-Wei
We determine the phase diagram of complete asymptotically free SU($N_c$) gauge theories featuring $N_s$ complex scalars and $N_f$ Dirac quarks transforming according to the fundamental representation of the gauge group. The analysis is performed at the maximum known order in perturbation theory. We unveil a very rich dynamics and associated phase structure. Intriguingly we discover that the complete asymptotically free conditions guarantee that the infrared dynamics displays long distance conformality, and in a regime when perturbation theory is applicable. We conclude our analysis by determining the quantum corrected potential of the theory and summarising the possible patterns of radiative symmetry breaking. These theories are of potential phenomenological interest as either elementary or composite ultraviolet finite extensions of the Standard Model.
Jan-e~Alam; Subhasis~Chattopadhyay; Tapan~Nayak
2008-10-01
Quark Matter 2008—the 20th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions was held in Jaipur, the Pink City of India, from 4-10 February, 2008. Organizing Quark Matter 2008 in India itself indicates the international recognition of the Indian contribution to the field of heavy-ion physics, which was initiated and nurtured by Bikash Sinha, Chair of the conference. The conference was inaugurated by the Honourable Chief Minister of Rajasthan, Smt. Vasundhara Raje followed by the key note address by Professor Carlo Rubbia. The scientific programme started with the theoretical overview, `SPS to RHIC and onwards to LHC' by Larry McLerran followed by several theoretical and experimental overview talks on the ongoing experiments at SPS and RHIC. The future experiments at the LHC, FAIR and J-PARC, along with the theoretical predictions, were discussed in great depth. Lattice QCD predictions on the nature of the phase transition and critical point were vigorously debated during several plenary and parallel session presentations. The conference was enriched by the presence of an unprecedented number of participants; about 600 participants representing 31 countries across the globe. This issue contains papers based on plenary talks and oral presentations presented at the conference. Besides invited and contributed talks, there were also a large number of poster presentations. Members of the International Advisory Committee played a pivotal role in the selection of speakers, both for plenary and parallel session talks. The contributions of the Organizing Committee in all aspects, from helping to prepare the academic programme down to arranging local hospitality, were much appreciated. We thank the members of both the committees for making Quark Matter 2008 a very effective and interesting platform for scientific deliberations. Quark Matter 2008 was financially supported by: Air Liquide (New Delhi) Board of Research Nuclear Sciences (Mumbai) Bose
Light hadron spectroscopy with two flavors of $O(a)$-improved dynamical quarks
Aoki, S; Fukugita, M; Hashimoto, S; Ishikawa, K I; Ishizuka, N; Iwasaki, Y; Kanaya, K; Kaneko, T; Kuramashi, Y; Okawa, M; Onogi, T; Tsutsui, N; Ukawa, A; Yamada, N; Yoshié, T
2003-01-01
We present a high statistics study of the light hadron spectrum and quark masses in QCD with two flavors of dynamical quarks. Numerical simulations are carried out using the plaquette gauge action and the O(a)-improved Wilson quark action at \\beta=5.2, where the lattice spacing is found to be a=0.0887(11)fm from \\rho meson mass, on a 20^3\\times 48 lattice. At each of five sea quark masses corresponding to m_{PS}/m_{V} \\simeq 0.8-0.6, we generate 12000 trajectories using the symmetrically preconditioned Hybrid Monte Carlo algorithm. Finite spatial volume effects are investigated employing 12^3 \\times 48, 16^3 \\times 48 lattices. We also perform a set of simulations in quenched QCD with the same lattice actions at a similar lattice spacing to those for the full QCD runs. In the meson sector we find clear evidence of sea quark effects. The J parameter increases for lighter sea quark masses, and the full QCD meson masses are systematically closer to experiment than in quenched QCD. Careful finite-size studies are...
Heavy quark production in neutrino deep-inelastic scattering
Energy Technology Data Exchange (ETDEWEB)
Johnson, J.A.; Vakili, M.; Wu, V. [University of Cincinnati, Cincinnati, Ohio 45221 (United States); Bazarko, A.O.; Conrad, J.M.; Formaggio, J.A.; Kim, J.H.; King, B.J.; Koutsoliotas, S.; McNulty, C.; Mishra, S.R.; Romosan, A.; Sculli, F.J.; Seligman, W.G.; Shaevitz, M.H.; Spentzouris, P.; Stern, E.G.; Tamminga, B.M.; Vaitaitis, A. [Columbia University, New York, New York 10027 (United States); Bugel, L.; Lamm, M.J.; Marsh, M.; Nienaber, P.; Yu, J. [Fermilab, Batavia, Illinois 60510 (United States); Alton, A.; Bolton, T.; Goldman, J.; Goncharov, M.; Naples, D. [Kansas State University, Manhattan, Kansas 66506 (United States); Buchholz, D.; Harris, D.A.; Schellman, H.M.; Zeller, G.P. [Northwestern University, Evanston, Illinois 97403 (United States); Drucker, R.B.; Frey, R.; Mason, D. [University of Oregon, Eugene, Oregon 97403 (United States); de Barbaro, P.; Bodek, A.; Budd, H.; McFarland, K.S.; Sakumoto, W.K.; Yang, U.K. [University of Rochester, Rochester, New York 14627 (United States); Smith, W.H. [University of Wisconsin, Madison, Wisconsin 45207 (United States)
1999-02-01
Charm production by neutrino charged-current interactions produces two muon (dimuon) events which are easily identified. This signal provides an important method to measure the strange sea and the mass of the charm quark. Several experiments, including CCFR, CDHS and CHARM II, have performed analyses of such events. The results of these analyses are summarized with emphasis on CCFR and improvements made by NuTeV. {copyright} {ital 1999 American Institute of Physics.}
Floquet-Engineered Valleytronics in Dirac Systems.
Kundu, Arijit; Fertig, H A; Seradjeh, Babak
2016-01-08
Valley degrees of freedom offer a potential resource for quantum information processing if they can be effectively controlled. We discuss an optical approach to this problem in which intense light breaks electronic symmetries of a two-dimensional Dirac material. The resulting quasienergy structures may then differ for different valleys, so that the Floquet physics of the system can be exploited to produce highly polarized valley currents. This physics can be utilized to realize a valley valve whose behavior is determined optically. We propose a concrete way to achieve such valleytronics in graphene as well as in a simple model of an inversion-symmetry broken Dirac material. We study the effect numerically and demonstrate its robustness against moderate disorder and small deviations in optical parameters.
Dirac neutrino masses from generalized supersymmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Demir, D.A. [Izmir Institute of Technology, IZTECH, Izmir (Turkey). Dept. of Physics]|[Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Everett, L.L. [University of Wisconsin, Madison, WI (United States), Dept. of Physics; Langacker, P. [Institute for Advanced Study, Princeton, NJ (United States). School of Natural Sciences
2007-12-15
We demonstrate that Dirac neutrino masses in the experimentally preferred range are generated within supersymmetric gauge extensions of the Standard Model with a generalized supersymmetry breaking sector. If the usual superpotential Yukawa couplings are forbidden by the additional gauge symmetry (such as a U(1){sup '}), effective Dirac mass terms involving the ''wrong Higgs'' field can arise either at tree level due to hard supersymmetry breaking fermion Yukawa couplings, or at one-loop due to nonanalytic or ''nonholomorphic'' soft supersymmetry breaking trilinear scalar couplings. As both of these operators are naturally suppressed in generic models of supersymmetry breaking, the resulting neutrino masses are naturally in the sub-eV range. The neutrino magnetic and electric dipole moments resulting from the radiative mechanism also vanish at one-loop order. (orig.)
Dirac Gauginos in Low Scale Supersymmetry Breaking
Goodsell, Mark D
2014-01-01
It has been claimed that Dirac gaugino masses are necessary for realistic models of low-scale supersymmetry breaking, and yet very little attention has been paid to the phenomenology of a light gravitino when gauginos have Dirac masses. We begin to address this deficit by investigating the couplings and phenomenology of the gravitino in the effective Lagrangian approach. We pay particular attention to the phenomenology of the scalar octets, where new decay channels open up. This leads us to propose a new simplified effective scenario including only light gluinos, sgluons and gravitinos, allowing the squarks to be heavy -- with the possible exception of the third generation. Finally, we comment on the application of our results to Fake Split Supersymmetry.
Dirac gauginos in low scale supersymmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Goodsell, Mark D., E-mail: mark.goodsell@lpthe.jussieu.fr [Sorbonne Universités, UPMC Univ. Paris 06, UMR 7589, LPTHE, F-75005, Paris (France); CNRS, UMR 7589, LPTHE, F-75005, Paris (France); Tziveloglou, Pantelis, E-mail: pantelis.tziveloglou@vub.ac.be [Theoretische Natuurkunde and IIHE, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels (Belgium); International Solvay Institutes, Brussels (Belgium)
2014-12-15
It has been claimed that Dirac gaugino masses are necessary for realistic models of low-scale supersymmetry breaking, and yet very little attention has been paid to the phenomenology of a light gravitino when gauginos have Dirac masses. We begin to address this deficit by investigating the couplings and phenomenology of the gravitino in the effective Lagrangian approach. We pay particular attention to the phenomenology of the scalar octets, where new decay channels open up. This leads us to propose a new simplified effective scenario including only light gluinos, sgluons and gravitinos, allowing the squarks to be heavy – with the possible exception of the third generation. Finally, we comment on the application of our results to Fake Split Supersymmetry.
Chiral scars in chaotic Dirac fermion systems.
Xu, Hongya; Huang, Liang; Lai, Ying-Cheng; Grebogi, Celso
2013-02-08
Do relativistic quantum scars in classically chaotic systems possess unique features that are not shared by nonrelativistic quantum scars? We report a class of relativistic quantum scars in massless Dirac fermion systems whose phases return to the original values or acquire a 2π change only after circulating twice about some classical unstable periodic orbits. We name such scars chiral scars, the successful identification of which has been facilitated tremendously by our development of an analytic, conformal-mapping-based method to calculate an unprecedentedly large number of eigenstates with high accuracy. Our semiclassical theory indicates that the physical origin of chiral scars can be attributed to a combined effect of chirality intrinsic to massless Dirac fermions and the geometry of the underlying classical orbit.
BINARY NONLINEARIZATION FOR THE DIRAC SYSTEMS
Institute of Scientific and Technical Information of China (English)
MAWENXIU
1997-01-01
A Bargmann symmetry constraint is proposed for the Lax pairs and the adjoint Lax pairs of the Dirac systems. It is shown that the spatial part of the nonlinearized Lax pairs and adjoint Lax pairs is a finite dimensional Linuville integrable Hamiltonian system and that under the control of the spatial part, the time parts of the nonlinearized Lax pairs and adjoint Lax pairs are interpreted as a hierarchy of commutative, finite dimensional Linuville integrable Hamiltoian systems whose Hamiltonian functions consist of a series of integrals of motion for the spatial part. Moreover an invaiutive representation of solutions of the Dirac systems exhibits their integrability by quadratures. This kind of symmetry constraint procedure involving thespectral problem and the adjoint spectral problem is referred to as a binary nonlinearization technique like a binary Darhoux transformation.
Plexciton Dirac points and topological modes
Energy Technology Data Exchange (ETDEWEB)
Yuen-Zhou, Joel [Univ. of California, San Diego, CA (United States); Saikin, Semion K. [Harvard Univ., Cambridge, MA (United States); Kazan Federal Univ. (Russia); Zhu, Tony [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Onbasli, Mehmet C. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Ross, Caroline A. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Bulovic, Vladimir [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Baldo, Marc A. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
2016-06-09
Plexcitons are polaritonic modes that result from the strong coupling between excitons and plasmons. Here, we consider plexcitons emerging from the interaction of excitons in an organic molecular layer with surface plasmons in a metallic film. We predict the emergence of Dirac cones in the two-dimensional band-structure of plexcitons due to the inherent alignment of the excitonic transitions in the organic layer. An external magnetic field opens a gap between the Dirac cones if the plexciton system is interfaced with a magneto-optical layer. The resulting energy gap becomes populated with topologically protected one-way modes, which travel at the interface of this plexcitonic system. Our theoretical proposal suggests that plexcitons are a convenient and simple platform for the exploration of exotic phases of matter and for the control of energy flow at the nanoscale.
LHCb: Pilot Framework and the DIRAC WMS
Graciani, R; Casajus, A
2009-01-01
DIRAC, the LHCb community Grid solution, has pioneered the use of pilot jobs in the Grid. Pilot jobs provide a homogeneous interface to an heterogeneous set of computing resources. At the same time, pilot jobs allow to delay the scheduling decision to the last moment, thus taking into account the precise running conditions at the resource and last moment requests to the system. The DIRAC Workload Management System provides one single scheduling mechanism for jobs with very different profiles. To achieve an overall optimisation, it organizes pending jobs in task queues, both for individual users and production activities. Task queues are created with jobs having similar requirements. Following the VO policy a priority is assigned to each task queue. Pilot submission and subsequent job matching are based on these priorities following a statistical approach. Details of the implementation and the security aspects of this framework will be discussed.
Thermometry for Dirac fermions in graphene
Energy Technology Data Exchange (ETDEWEB)
Liu, Fan-Hung; Hsu, Chang-Shun; Lo, Shun-Tsung [National Taiwan University, Taipei, Taiwan (China); and others
2015-01-15
We use both the zero-magnetic-field resistivity and the phase coherence time determined by weak localization as independent thermometers for Dirac fermions (DF) in multilayer graphene. In the high current (I) region, there exists a simple power law T{sub DF} ∼ I{sup ∼0.5}, where T{sub DF} is the effective Dirac fermion temperature for epitaxial graphene on SiC. In contrast, T{sub DF} ∼ I{sup ∼1} in exfoliated multilayer graphene. We discuss possible reasons for the different power laws observed in these multilayer graphene systems. Our experimental results on DF-phonon scattering may find applications in graphene-based nanoelectronics.
Dirac Geometry of the Holonomy Fibration
Cabrera, Alejandro; Meinrenken, Eckhard
2015-01-01
In this paper, we solve the problem of giving a gauge-theoretic description of the natural Dirac structure on a Lie Group which plays a prominent role in the theory of D- branes for the Wess-Zumino-Witten model as well as the theory of quasi-Hamiltonian spaces. We describe the structure as an infinite-dimensional reduction of the space of connections over the circle. Our insight is that the formal Poisson structure on the space of connections is not an actual Poisson structure, but is itself a Dirac structure, due to the fact that it is defined by an unbounded operator. We also develop general tools for reducing Courant algebroids and morphisms between them, allowing us to give a precise correspondence between Hamiltonian loop group spaces and quasi- Hamiltonian spaces.
Classical behaviour of the Dirac bispinor
Bell, S B M; Díaz, B M; Bell, Sarah B. M.; Cullerne, John P.; Diaz, Bernard M.
2000-01-01
It is usually supposed that the Dirac and radiation equations predict that the phase of a fermion will rotate through half the angle through which the fermion is rotated, which means, via the measured dynamical and geometrical phase factors, that the fermion must have a half-integral spin. We demonstrate that this is not the case and that the identical relativistic quantum mechanics can also be derived with the phase of the fermion rotating through the same angle as does the fermion itself. Under spatial rotation and Lorentz transformation the bispinor transforms as a four-vector like the potential and Dirac current. Previous attempts to provide this form of transformational behaviour have foundered because a satisfactory current could not be derived.(14)
Octonion generalization of Pauli and Dirac matrices
Chanyal, B. C.
2015-10-01
Starting with octonion algebra and its 4 × 4 matrix representation, we have made an attempt to write the extension of Pauli's matrices in terms of division algebra (octonion). The octonion generalization of Pauli's matrices shows the counterpart of Pauli's spin and isospin matrices. In this paper, we also have obtained the relationship between Clifford algebras and the division algebras, i.e. a relation between octonion basis elements with Dirac (gamma), Weyl and Majorana representations. The division algebra structure leads to nice representations of the corresponding Clifford algebras. We have made an attempt to investigate the octonion formulation of Dirac wave equations, conserved current and weak isospin in simple, compact, consistent and manifestly covariant manner.
Quantum simulation of the Dirac equation
Gerritsma, R; Zähringer, F; Solano, E; Blatt, R; Roos, C F
2009-01-01
The Dirac equation is a cornerstone in the history of physics, merging successfully quantum mechanics with special relativity, providing a natural description of the electron spin and predicting the existence of anti-matter. Furthermore, it is able to reproduce accurately the spectrum of the hydrogen atom and its realm, relativistic quantum mechanics, is considered as the natural transition to quantum field theory. However, the Dirac equation also predicts some peculiar effects such as Klein's paradox and Zitterbewegung, an unexpected quivering motion of a free relativistic quantum particle first examined by Schr\\"odinger. These and other predictions would be difficult to observe in real particles, while constituting key fundamental examples to understand relativistic quantum effects. Recent years have seen an increased interest in simulations of relativistic quantum effects in different physical setups, where parameter tunability allows accessibility to different physical regimes. Here, we perform a proof-of...
Classical electromagnetic radiation of the Dirac electron
Lanyi, G.
1973-01-01
A wave-function-dependent four-vector potential is added to the Dirac equation in order to achieve conservation of energy and momentum for a Dirac electron and its emitted electromagnetic field. The resultant equation contains solutions which describe transitions between different energy states of the electron. As a consequence it is possible to follow the space-time evolution of such a process. This evolution is shown in the case of the spontaneous emission of an electromagnetic field by an electron bound in a hydrogen-like atom. The intensity of the radiation and the spectral distribution are calculated for transitions between two eigenstates. The theory gives a self-consistent deterministic description of some simple radiation processes without using quantum electrodynamics or the correspondence principle.
Clustered Quark Matter Calculation for Strange Quark Matter
Na, Xuesen
2009-01-01
Motivated by the need for a solid state strange quark matter to better explain some observational phenomena, we discussed possibility of color singlet cluster formation in cold strange quark matter by a rough calculation following the excluded volume method proposed by Clark et al (1986) and adopted quark mass density dependent model with cubic scaling. It is found that 70% to 75% of volume and 80% to 90% of baryon number is in clusters at temperature from 10MeV to 50MeV and 1 to 10 times nuclear density.
Dirac particle in a pseudoscalar potential
Energy Technology Data Exchange (ETDEWEB)
Moreno, M. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Ap. Postal 20-364, 01000 (Mexico), D.F.; Zentella-Dehesa, A. [Departamento de Fisicoquimica, Intituto de Quimica, UNAM Ap. Postal 70-213, 04510 (Mexico), D.F.
1996-02-01
We study the problem of a Dirac particle with a pseudoscalar interaction in the potential approximation. It is shown how nonperturbative relativistic solutions arise. The case of the central pseudoscalar potential is explicitly worked out also in a closed form. The angular functions are worked out in general for this central case. Finally for the special case of the spherical well the radial solutions are shown to behave like Bessel-type functions. {copyright} {ital 1996 American Institute of Physics.}
Gauge Identities and the Dirac Conjecture
Rothe, Heinz J.; Rothe, Klaus D.
2004-01-01
The gauge symmetries of a general dynamical system can be systematically obtained following either a Hamiltonean or a Lagrangean approach. In the former case, these symmetries are generated, according to Dirac's conjecture, by the first class constraints. In the latter approach such local symmetries are reflected in the existence of so called gauge identities. The connection between the two becomes apparent, if one works with a first order Lagrangean formulation. Our analysis applies to purel...
Dynamical seesaw mechanism for Dirac neutrinos
Directory of Open Access Journals (Sweden)
José W.F. Valle
2016-04-01
Full Text Available So far we have not been able to establish that, as theoretically expected, neutrinos are their own anti-particles. Here we propose a dynamical way to account for the Dirac nature of neutrinos and the smallness of their mass in terms of a new variant of the seesaw paradigm in which the energy scale of neutrino mass generation could be accessible to the current LHC experiments.
Dirac particles in a gravitational field
Energy Technology Data Exchange (ETDEWEB)
Gosselin, Pierre [UFR de Mathematiques, Universite Grenoble I, BP74, Institut Fourier, UMR 5582 CNRS-UJF, Saint Martin d' Heres Cedex (France); Mohrbach, Herve [Universite Paul Verlaine-Metz, Groupe BioPhysStat, ICPMB-FR CNRS 2843, Metz Cedex 3 (France)
2011-09-15
The semiclassical approximation for the Hamiltonian of Dirac particles interacting with an arbitrary gravitational field is investigated. The time dependence of the metric leads to new contributions to the in-band energy operator in comparison to previous works in the static case. In particular we find a new coupling term between the linear momentum and the spin, as well as couplings that contribute to the breaking of the particle-antiparticle symmetry. (orig.)
Quantum logic gates from Dirac quasiparticles
Marino, E. C.; Brozeguini, J. C.
2015-03-01
We show that one of the fundamental operations of topological quantum computation, namely the non-Abelian braiding of identical particles, can be physically realized in a general system of Dirac quasiparticles in 1 + 1D. Our method is based on the study of the analytic structure of the different Euclidean correlation functions of Dirac fields, which are conveniently expressed as functions of a complex variable. When the Dirac field is an (Abelian) anyon with statistics parameter s (2s not an integer), we show that the associated Majorana states of such a field present non-Abelian statistics. The explicit form of the unitary, non-commuting (monodromy) matrices generated upon braiding is derived as a function of s and is shown to satisfy the Yang-Baxter algebra. For the special case of s = 1/4, we show that the braiding matrices become the logic gates NOT, CNOT,… required in the algorithms of universal quantum computation. We suggest that maybe polyacetylene, alternately doped with alkali and halogen atoms, is a potential candidate for a physical material realization of the system studied here.
Quantum transport through 3D Dirac materials
Energy Technology Data Exchange (ETDEWEB)
Salehi, M. [Department of Physics, Sharif University of Technology, Tehran 11155-9161 (Iran, Islamic Republic of); Jafari, S.A., E-mail: jafari@physics.sharif.edu [Department of Physics, Sharif University of Technology, Tehran 11155-9161 (Iran, Islamic Republic of); Center of Excellence for Complex Systems and Condensed Matter (CSCM), Sharif University of Technology, Tehran 1458889694 (Iran, Islamic Republic of)
2015-08-15
Bismuth and its alloys provide a paradigm to realize three dimensional materials whose low-energy effective theory is given by Dirac equation in 3+1 dimensions. We study the quantum transport properties of three dimensional Dirac materials within the framework of Landauer–Büttiker formalism. Charge carriers in normal metal satisfying the Schrödinger equation, can be split into four-component with appropriate matching conditions at the boundary with the three dimensional Dirac material (3DDM). We calculate the conductance and the Fano factor of an interface separating 3DDM from a normal metal, as well as the conductance through a slab of 3DDM. Under certain circumstances the 3DDM appears transparent to electrons hitting the 3DDM. We find that electrons hitting the metal-3DDM interface from metallic side can enter 3DDM in a reversed spin state as soon as their angle of incidence deviates from the direction perpendicular to interface. However the presence of a second interface completely cancels this effect.
Manipulation of Dirac Cones in Mechanical Graphene
Kariyado, Toshikaze; Hatsugai, Yasuhiro
2015-12-01
Recently, quantum Hall state analogs in classical mechanics attract much attention from topological points of view. Topology is not only for mathematicians but also quite useful in a quantum world. Further it even governs the Newton’s law of motion. One of the advantages of classical systems over solid state materials is its clear controllability. Here we investigate mechanical graphene, which is a spring-mass model with the honeycomb structure as a typical mechanical model with nontrivial topological phenomena. The vibration spectrum of mechanical graphene is characterized by Dirac cones serving as sources of topological nontriviality. We find that the spectrum has dramatic dependence on the spring tension at equilibrium as a natural control parameter, i.e., creation and annihilation of the Dirac particles are realized as the tension increases. Just by rotating the system, the manipulated Dirac particles lead to topological transition, i.e., a jump of the “Chern number” occurs associated with flipping of propagating direction of chiral edge modes. This is a bulk-edge correspondence governed by the Newton’s law. A simple observation that in-gap edge modes exist only at the fixed boundary, but not at the free one, is attributed to the symmetry protection of topological phases.
Pseudospin symmetry in the Dirac phenomenology
Energy Technology Data Exchange (ETDEWEB)
Marcos, S.; Niembro, R. [Universidad de Cantabria, Departamento de Fisica Moderna, Santander (Spain); Lopez-Quelle, M. [Universidad de Cantabria, Departamento de Fisica Aplicada, Santander (Spain); Savushkin, L.N. [St. Petersburg University for Telecommunications, Department of Physics, St. Petersburg (Russian Federation)
2007-12-15
In the phenomenological relativistic framework of the Dirac equation for spherical nuclei, we use different kinds of single-particle central potentials ({sigma}{sub S}+{sigma}{sub 0}) to investigate certain aspects of the spin and pseudospin (PS) symmetries. Neither the splitting of PS doublets (PSDs) nor the similarity of the radial parts of the small components (F/r) of the corresponding Dirac spinors have been found related with the magnitude of {sigma}{sub S}+{sigma}{sub 0}, in the sense predicted by several authors in the last decade. This conclusion is shown to be valid, in particular, for a potential of Coulomb type. We give a simple explanation for the strong correlation established in the relativistic calculations between the similarity of the radial parts of the big (small) components of the Dirac spinors of two spin (pseudospin) partners and the number of their nodes. The direct effects of the so-called PS symmetry-breaking term (and its singularity point) on the F functions of the PSDs are also analysed. (orig.)
A Dynamical Framework for KeV Dirac Neutrino Warm Dark Matter
Robinson, Dean J
2014-01-01
If the source of the reported $3.5$ keV x-ray line is a sterile neutrino, comprising an $\\mathcal{O}(1)$ fraction of the dark matter (DM), then it exhibits the property that its mass times mixing angle is $\\sim 10^{-2}$ eV, a plausible mass scale for the active neutrinos. This property is a common feature of Dirac neutrino mixing. We present a framework that dynamically produces light active and keV sterile Dirac neutrinos, with appropriate mixing angles to be the x-ray line source. The central idea is that the right-handed active neutrino is a composite state, while elementary sterile neutrinos gain keV masses similarly to the quarks in extended Technicolor. The entire framework is fixed by just two dynamical scales and automatically exhibits a warm dark matter (WDM) production mechanism -- dilution of thermal relics from late decays of a heavy composite neutrino -- such that the keV neutrinos may comprise an $\\mathcal{O}(1)$ fraction of the DM. In this framework, the WDM is typically quite cool $\\sim 0.02~T...
Dynamical framework for KeV Dirac neutrino warm dark matter
Robinson, Dean J.; Tsai, Yuhsin
2014-08-01
If the source of the reported 3.5 keV x-ray line is a sterile neutrino, comprising an O(1) fraction of the dark matter (DM), then it exhibits the property that its mass times mixing angle is ˜ few×10-2 eV, a plausible mass scale for the active neutrinos. This property is a common feature of Dirac neutrino mixing. We present a framework that dynamically produces light active and keV sterile Dirac neutrinos, with appropriate mixing angles to be the x-ray line source. The central idea is that the right-handed active neutrino is a composite state, while elementary sterile neutrinos gain keV masses similarly to the quarks in extended technicolor. The entire framework is fixed by just two dynamical scales and may automatically exhibit a warm dark matter (WDM) production mechanism—dilution of thermal relics from late decays of a heavy composite neutrino—such that the keV neutrinos may comprise an O(1) fraction of the DM. In this framework, the WDM is typically quite cool and within structure formation bounds, with temperature ˜ few×10-2Tν and free-streaming length ˜ few kpc. A toy model that exhibits the central features of the framework is also presented.
Evidence for production of single top quarks
Abazov, V.M.; et al., [Unknown; de Jong, S.J.; Demarteau, M.; Houben, P.; van den Berg, P.J.
2008-01-01
We present first evidence for the production of single top quarks in the D0 detector at the Fermilab Tevatron p (p) over bar collider. The standard model predicts that the electroweak interaction can produce a top quark together with an antibottom quark or light quark, without the antiparticle top-q
Top Quark Properties Measurements in CMS
Yazgan, Efe
Recent top quark properties measurements made with the CMS detector at the LHC are presented. The measurements summarized include spin correlation of top quark pairs, asymmetries, top quark mass, and the underlying event in top quark pair events. The results are compared to the standard model predictions and new physics models.
Top quark properties at ATLAS and CMS
Brock, Ian; The ATLAS collaboration
2016-01-01
Recent results from ATLAS and CMS connected to the properties of the top quark are presented. The talk concentrates on asymmetries connected with top-quark production and the measurement of spin correlations between the top quark and antiquark. A search for CP violation in top-quark-antiquark production is also discussed.
Top quark properties measurements in CMS
Yazgan, E.; CMS Collaboration
2017-07-01
Recent top quark properties measurements made with the CMS detector at the LHC are presented. The measurements summarized include spin correlation of top quark pairs, asymmetries, top quark mass, and the underlying event in top quark pair events. The results are compared to the standard model predictions and new physics models.
Matsuda, K; Matsuda, Koichi; Nishiura, Hiroyuki
2006-01-01
We reconsider an universal mass matrix model which has a seesaw-invariant structure with four-zero texture common to all quarks and leptons. The CKM quark and MNS lepton mixing matrices of the model are analyzed analytically.We show that the model can be consistent with all the experimental data of neutrino oscillation and quark mixings by tuning free parameters of the model. It is also shown that the model predicts a relatively large value for (1,3) element of the MNS lepton mixing matrix, |(U_{MNS})_{13}|^2 \\simeq 2.6 \\times 10^{-2}. Using the seesaw mechanism, we also discuss the conditions for the components of the Dirac and the right-handed Majorana neutrino mass matrices which lead to the neutrino mass matrix consistent with the experimental data.
Quark Virtuality and QCD Vacuum Condensates
Institute of Scientific and Technical Information of China (English)
ZHOU Li-Juan; MA Wei-Xing
2004-01-01
@@ Based on the Dyson-Schwinger equations (DSEs) in the ‘rainbow' approximation, we investigate the quark virtuality in the vacuum state and quantum-chromodynamics (QCD) vacuum condensates. In particular, we calculate the local quark vacuum condensate and quark-gluon mixed condensates, and then the virtuality of quark. The calculated quark virtualities are λ2u,d = 0.7 GeV2 for u, d quarks, and 2s 1.6 GeV2 for s quark.Our theoretical predictions are consistent with empirical values used in QCD sum rules, and also fit to lattice QCD predictions.
Top quark studies at hadron colliders
Energy Technology Data Exchange (ETDEWEB)
Sinervo, P.K. [Univ. of Toronto, Ontario (Canada)
1997-01-01
The techniques used to study top quarks at hadron colliders are presented. The analyses that discovered the top quark are described, with emphasis on the techniques used to tag b quark jets in candidate events. The most recent measurements of top quark properties by the CDF and DO Collaborations are reviewed, including the top quark cross section, mass, branching fractions, and production properties. Future top quark studies at hadron colliders are discussed, and predictions for event yields and uncertainties in the measurements of top quark properties are presented.
Dirac Spectrum of the Wilson Dirac Operator for QCD with Two Colors
Kieburg, Mario; Zafeiropoulos, Savvas
2015-01-01
We study the lattice artefacts of the Wilson Dirac operator for QCD with two colors and fermions in the fundamental representation from the viewpoint of chiral perturbation theory. These effects are studied with the help of the following spectral observables: the level density of the Hermitian Wilson Dirac operator, the distribution of chirality over the real eigenvalues, and the chiral condensate for the quenched as well as for the unquenched theory. We provide analytical expressions for all these quantities. Moreover we derive constraints for the level density of the real eigenvalues of the non-Hermitian Wilson Dirac operator and the number of additional real modes. The latter is a good measure for the strength of lattice artefacts. All computations are confirmed by Monte Carlo simulations of the corresponding random matrix theory which agrees with chiral perturbation theory of two color QCD with Wilson fermions.
Tunable multiple layered Dirac cones in optical lattices.
Lan, Z; Celi, A; Lu, W; Öhberg, P; Lewenstein, M
2011-12-16
We show that multiple layered Dirac cones can emerge in the band structure of properly addressed multicomponent cold fermionic gases in optical lattices. The layered Dirac cones contain multiple copies of massless spin-1/2 Dirac fermions at the same location in momentum space, whose different Fermi velocity can be tuned at will. On-site microwave Raman transitions can further be used to mix the different Dirac species, resulting in either splitting of or preserving the Dirac point (depending on the symmetry of the on-site term). The tunability of the multiple layered Dirac cones allows us to simulate a number of fundamental phenomena in modern physics, such as neutrino oscillations and exotic particle dispersions with E~p(N) for arbitrary integer N.
Type-II Symmetry-Protected Topological Dirac Semimetals
Chang, Tay-Rong; Xu, Su-Yang; Sanchez, Daniel S.; Tsai, Wei-Feng; Huang, Shin-Ming; Chang, Guoqing; Hsu, Chuang-Han; Bian, Guang; Belopolski, Ilya; Yu, Zhi-Ming; Yang, Shengyuan A.; Neupert, Titus; Jeng, Horng-Tay; Lin, Hsin; Hasan, M. Zahid
2017-07-01
The recent proposal of the type-II Weyl semimetal state has attracted significant interest. In this Letter, we propose the concept of the three-dimensional type-II Dirac fermion and theoretically identify this new symmetry-protected topological state in the large family of transition-metal icosagenides, M A3 (M =V , Nb, Ta; A =Al , Ga, In). We show that the VAl3 family features a pair of strongly Lorentz-violating type-II Dirac nodes and that each Dirac node can be split into four type-II Weyl nodes with chiral charge ±1 via symmetry breaking. Furthermore, we predict that the Landau level spectrum arising from the type-II Dirac fermions in VAl3 is distinct from that of known Dirac or Weyl semimetals. We also demonstrate a topological phase transition from a type-II Dirac semimetal to a quadratic Weyl semimetal or a topological crystalline insulator via crystalline distortions.
Spectrum of the Wilson Dirac operator at finite lattice spacings
DEFF Research Database (Denmark)
Akemann, G.; Damgaard, Poul Henrik; Splittorff, Kim;
2011-01-01
We consider the effect of discretization errors on the microscopic spectrum of the Wilson Dirac operator using both chiral Perturbation Theory and chiral Random Matrix Theory. A graded chiral Lagrangian is used to evaluate the microscopic spectral density of the Hermitian Wilson Dirac operator...... as well as the distribution of the chirality over the real eigenvalues of the Wilson Dirac operator. It is shown that a chiral Random Matrix Theory for the Wilson Dirac operator reproduces the leading zero-momentum terms of Wilson chiral Perturbation Theory. All results are obtained for fixed index...... of the Wilson Dirac operator. The low-energy constants of Wilson chiral Perturbation theory are shown to be constrained by the Hermiticity properties of the Wilson Dirac operator....
Pseudo-Dirac dark matter leaves a trace.
De Simone, Andrea; Sanz, Veronica; Sato, Hiromitsu Phil
2010-09-17
Pseudo-Dirac dark matter is a viable type of dark matter which originates from a new Dirac fermion whose two Weyl states get slightly split in mass by a small Majorana term. The decay of the heavier to the lighter state naturally occurs over a detectable length scale. Thus, whenever pseudo-Dirac dark matter is produced in a collider, it leaves a clear trace: a visible displaced vertex in association with missing energy. Moreover, pseudo-Dirac dark matter behaves Dirac-like for relic abundance and Majorana-like in direct detection experiments. We provide a general effective field theory treatment, specializing to a pseudo-Dirac bino. The dark matter mass and the mass splitting can be extracted from measurements of the decay length and the invariant mass of the products, even in the presence of missing energy.
DIRAC - The Distributed MC Production and Analysis for LHCb
Tsaregorodtsev, A; Closier, J; Frank, M; Garonne, V; Witek, M; Romanovski, V; Egede, U; Vagnoni, V; Korolko, I; Blouw, J; Kuznetsov, G; Patrick, G; Gandelman, M; Graciani-Diaz, R; Bernet, R; Brook, N; Pickford, A; Tobin, M; Saroka, A; Stokes-Rees, I; Saborido-Silva, J; Sanchez-Garcia, M
2004-09-30
DIRAC is the LHCb distributed computing grid infrastructure for Monte Carlo (MC) production and analysis. Its architecture is based on a set of distributed collaborating services. The service decomposition broadly follows the CERN/ARDA-RTAG proposal, which should allow for the interchange of the EGEE/gLite and DIRAC components. In this paper we give an overview of the DIRAC architecture, as well as the main design choices in its implementation. The light nature and modular design of the DIRAC components allows its functionality to be easily extended to include new computing and storage elements or to handle new types of tasks. The DIRAC system already uses different types of computing resources - from single PC's to a variety of batch systems and to the Grid environment. In particular, the DIRAC interface to the LCG2 grid will be presented.
DIRAC The Distributed MC Production and Analysis for LHCb
Bernet, R; Brook, N; Charpentier, P; Closier, J; Egede, U; Frank, M; Gandelman, M; Garonne, V; Graciani-Díaz, R; Korolko, I; Kuznetsov, G; Patrick, G; Pickford, A; Romanovski, V G; Saborido-Silva, J J; Sánchez-García, M; Saroka, A; Stokes-Rees, I; Tobin, M; Tsaregorodtsev, A Yu; Vagnoni, V; Witek, M
2005-01-01
DIRAC is the LHCb distributed computing grid infrastructure for MC production and analysis. Its architecture is based on a set of distributed collaborating services. The service decomposition broadly follows the CERN/ARDA-RTAG proposal, which can eventually make possible the interchange of the EGEE/gLite and DIRAC components. In this paper we give an overview of the DIRAC architecture, as well as the main design choices in its implementation. The light nature and modular design of the DIRAC components allows its functionality to be easily extended to include new computing and storage elements or to handle new types of tasks. The DIRAC system already uses different types of computing resources - from single PC's to a variety of batch systems and to the Grid environment. In particular, the DIRAC interface to the LCG2 grid will be presented.
Energy Technology Data Exchange (ETDEWEB)
Menzione, A. [INFN Sezione di Pisa (Italy)
1995-10-01
Most of the material presented in this report, comes from contributions to the parallel session PL20 of this conference. We summarise the experimental results of direct production of Top quarks, coming from the CDF and C0 Collaborations at Fermilab, and compare these results to what one expects within current theoretical understanding. Particular attention is given to new results such as all hadronic modes of t{bar t} decay. As far as the mass is concerned, a comparison is made with precision measurements of related quantities, coming from LEP and other experiments. An attempt is made to look at the medium-term future and understand which variables and with what accuracy one can measure them with increased integrated luminosity.
Melting Hadrons, Boiling Quarks
Rafelski, Johann
2015-01-01
In the context of the Hagedorn temperature half-centenary I describe our understanding of the hot phases of hadronic matter both below and above the Hagedorn temperature. The first part of the review addresses many frequently posed questions about properties of hadronic matter in different phases, phase transition and the exploration of quark-gluon plasma (QGP). The historical context of the discovery of QGP is shown and the role of strangeness and strange antibaryon signature of QGP illustrated. In the second part I discuss the corresponding theoretical ideas and show how experimental results can be used to describe the properties of QGP at hadronization. Finally in two appendices I present previously unpublished reports describing the early prediction of the different forms of hadron matter and of the formation of QGP in relativistic heavy ion collisions, including the initial prediction of strangeness and in particular strange antibaryon signature of QGP.
Melting hadrons, boiling quarks
Energy Technology Data Exchange (ETDEWEB)
Rafelski, Johann [CERN-PH/TH, Geneva 23 (Switzerland); The University of Arizona, Department of Physics, Tucson, Arizona (United States)
2015-09-15
In the context of the Hagedorn temperature half-centenary I describe our understanding of the hot phases of hadronic matter both below and above the Hagedorn temperature. The first part of the review addresses many frequently posed questions about properties of hadronic matter in different phases, phase transition and the exploration of quark-gluon plasma (QGP). The historical context of the discovery of QGP is shown and the role of strangeness and strange antibaryon signature of QGP illustrated. In the second part I discuss the corresponding theoretical ideas and show how experimental results can be used to describe the properties of QGP at hadronization. The material of this review is complemented by two early and unpublished reports containing the prediction of the different forms of hadron matter, and of the formation of QGP in relativistic heavy ion collisions, including the discussion of strangeness, and in particular strange antibaryon signature of QGP. (orig.)
Thorndike, Edward H.; Poling, Ronald A.
1988-01-01
Recent experimental results on the decay of b-flavored hadrons are reviewed. Substantial progress has been made in the study of exclusive and inclusive B-meson decays, as well as in the theoretical understanding of these processes. The two most prominent developments are the continuing failure to observe evidence of decays of the b quark to a u quark rather than a c quark, and the surprisingly high level of B 0- overlineB0 mi xing which has recently been reported by the ARGUS collaboration. Notwithstanding these results, we conclude that the health of the Standard Model is excellent.
Matute, Ernesto A
2015-01-01
An extension of the Standard Model (SM) is studied in which two right-handed (RH) neutrinos per generation are incorporated, but considering the hypothesis of the symmetry of lepton and quark contents in order to deprive the number of RH neutrinos of freedom, generate Dirac neutrinos and accommodate naturally tiny values for their masses. The high scale type-I seesaw regime is applied to the first, ordinary RH neutrino, whereas a low scale pseudo-Dirac scenario is used for the second, adulterant RH neutrino, implying that the first RH neutrino decouples at the high scale, while the second RH neutrino survives down to the low scale to pair off in a Dirac-like form with the corresponding left-handed (LH) neutrino. The small mass and couplings of this extra RH neutrino are explained by means of the statement of the symmetry of fermionic content, only regarded as a guideline to the natural choice of parameters since it is not a proper symmetry in the Lagrangian.
Classifying the Phases of Gauge Theories by Spectral Density of Probing Chiral Quarks
Alexandru, Andrei
2015-01-01
We describe our recent proposal that distinct phases of gauge theories with fundamental quarks translate into specific types of low-energy behavior in Dirac spectral density. The resulting scenario is built around new evidence substantiating the existence of a phase characterized by bimodal (anomalous) density, and corresponding to deconfined dynamics with broken valence chiral symmetry. We argue that such anomalous phase occurs quite generically in these theories, including in "real world" QCD above the crossover temperature, and in zero-temperature systems with many light flavors.
Measurement of W-Boson Helicity Fractions in Top-Quark Decays Using costheta*
Aaltonen, T; Adelman, J; Akimoto, T; Alvarez Gonzlez, B; Ameriow, a S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Apollinari, G; Apresyan, A; Arisawa, T; Artikov, A; Ashmanskas, W; Attal, A; Aurisano, A; Azfar, F; Azzurriz, P; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Bartsch, V; Bauer, G; Beauchemin, P H; Bedeschi, F; Beecher, D; Behari, S; Bellettini, Giorgio; Bellinger, J; Benjamin, D; Beretvas, A; Beringer, J; Bhatti, A; Binkley, M; Bisellow, D; Bizjakcc, I; Blair, R E; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Boisvert, V; Bölla, G; Bortoletto, D; Boudreau, J; Boveia, A; Braua, B; Bridgeman, A; Brigliadori, L; Bromberg, C; Brubaker, E; Budagov, Yu; Budd, H S; Budd, S; Burke, S; Burkett, K; Busettow, G; Busseyk, P; Buzatu, A; Byrum, K L; Cabrerau, S; Calancha, C; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carls, B; Carlsmith, D; Carosi, R; Carrillom, S; Carron, S; Casal, B; Casarsa, M; Castrov, A; Catastiniy, P; Cauzbb, D; Cavalierey, V; Cavalli-Sforza, M; Cerri, A; Cerriton, L; Chang, S H; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, K; Chokheli, D; Chou, J P; Choudalakis, G; Chuang, S H; Chung, K; Chung, W H; Chung, Y S; Chwalek, T; Ciobanu, C I; Ciocciy, M A; Clark, A; Clark, D; Compostella, G; Convery, M E; Conway, J; Cordelli, M; Cortianaw, G; Cox, C A; Cox, D J; Cresciolix, F; Cuenca Almenaru, C; Cuevasr, J; Culbertson, R; Cully, J C; Dagenhart, D; Datta, M; Davies, T; De Barbaro, P; De Cecco, S; Deisher, A; De Lorenzo, G; Dell'Orsox, M; Deluca, C; Demortier, L; Deng, J; Deninno, M; Derwent, P F; di Giovanni, G P; Dionisiaa, C; Di Ruzzabb, B; Dittmann, J R; D'Onofrio, M; Donatix, S; Dong, P; Donini, J; Dorigo, T; Dube, S; Efron, J; Elagin, A; Erbacher, R; Errede, D; Errede, S; Eusebi, R; Fang, H C; Farrington, S; Fedorko, W T; Feild, R G; Feindt, M; Fernández, J P; Ferrazzaz, C; Field, R; Flanagan, G; Forrest, R; Frank, M J; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; Garberson, F; García, J E; Garfinkel, A F; Genser, K; Gerberich, H; Gerdes, D; Gessler, A; Giaguaa, S; Giakoumopoulou, V; Giannetti, P; Gibson, K; Gimmell, J L; Ginsburg, C M; Giokaris, N; Giordanibb, M; Giromini, P; Giuntax, M; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldschmidt, N; Golossanov, A; Gómez, G; Gómez-Ceballos, G; Goncharov, M; Gonzlez, O; Gorelov, I; Goshaw, a A T; Goulianos, K; Greselew, A; Grinstein, S; Grosso-Pilcher, C; Group, R C; Grundler, U; Guimarães da Costa, J; Gunay-Unalan, Z; Haber, C; Hahn, K; Hahn, S R; Halkiadakis, E; Han, B Y; Han, J Y; Happacher, F; Hara, K; Hare, D; Hare, M; Harper, S; Harr, R F; Harris, R M; Hartz, M; Hatakeyama, K; Hays, C; Heck, M; Heijboer, A; Heinrich, J; Henderson, C; Herndon, M; Heuser, J; Hewamanage, S; Hidas, D; Hillc, C S; Hirschbuehl, D; Höcker, A; Hou, S; Houlden, M; Hsu, S C; Huffman, B T; Hughes, R E; Husemann, U; Hussein, M; Huston, J; Incandela, J; Introzzi, G; Ioriaa, M; Ivanov, A; James, E; Jayatilaka, B; Jeon, E J; Jha, M K; Jindariani, S; Johnson, W; Jones, M; Joo, K K; Jun, S Y; Jung, J E; Junk, T R; Kamon, T; Kar, D; Karchin, P E; Kato, Y; Kephart, R; Keung, J; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, H W; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kimura, N; Kirsch, L; Klimenko, S; Knuteson, B; Ko, B R; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kreps, M; Kroll, J; Krop, D; Krumnack, N; Kruse, M; Krutelyov, V; Kubo, T; Kuhr, T; Kulkarni, N P; Kurata, M; Kwang, S; Laasanen, A T; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannonq, K; Lath, A; Latinoy, G; Lazzizzeraw, I; LeCompte, T; Lee, E; Lee, H S; Leet, S W; Leone, S; Lewis, J D; Lin, C S; Linacre, J; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, C; Liu, T; Lockyer, N S; Loginov, A; Loretiw, M; Lovas, L; Lucchesiw, D; Luciaa, C; Lueck, J; Lujan, P; Lukens, P; Lungu, G; Lyons, L; Lys, J; Lysak, R; MacQueen, D; Madrak, R; Maeshima, K; Makhoul, K; Mäki, T; Maksimovic, P; Malde, S; Malik, S; Mancae, G; Manousakis-Katsikakis, A; Margaroli, F; Marino, C; Marino, C P; Martin, A; Martinl, V; Martínez, M; Martinez-Ballarin, R; Maruyama, T; Mastrandrea, P; Masubuchi, T; Mathis, ii M; Mattson, M E; Mazzanti, P; McFarland, K S; McIntyre, P; McNultyj, R; Mehta, A; Mehtälä, P; Menzione, A; Merkel, P; Mesropian, C; Miao, T; Miladinovic, N; Miller, R; Mills, C; Milnik, M; Mitra, A; Mitselmakher, G; Miyake, H; Moed, S; Moggi, N; Moon, C S; Moore, R; Morellox, M J; Morlok, J; Movilla-Fernández, P A; Mülmenstädt, J; Mukherjee, A; Müller, T; Mumford, R; Murat, P; Mussiniv, M; Nachtman, J; Nagai, Y; Nagano, A; Naganoma, J; Nakamura, K; Nakano, I; Napier, A; Necula, V; Nett, J; Neuv, C; Neubauer, M S; Neubauer, S; Nielseng, J; Nodulman, L; Norman, M; Norniella, O; Nurse, E; Oakes, L; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Orava, R; Pagan Grisow, S; Palencia, E; Papadimitriou, V; Papaikonomou, A; Paramonov, A A; Parks, B; Pashapour, S; Patrick, J; Paulettabb, G; Paulini, M; Paus, C; Peiffer, T; Pellett, D E; Penzo, Aldo L; Phillips, T J; Piacentino, G; Pianori, E; Pinera, L; Pitts, K; Plager, C; Pondrom, L; Poukhov, O; Pounder, N; Prakoshyn, F; Pronko, A; Proudfoot, J; Ptohosi, F; Pueschel, E; Punzix, G; Pursley, J; Rademackerc, J; Rahaman, A; Ramakrishnan, V; Ranjan, N; Redondo, I; Renton, P B; Renz, M; Rescigno, M; Richter, S; Rimondiv, F; Ristori, L; Robson, A; Rodrigo, T; Rodríguez, T; Rogers, E; Rolli, S; Roser, R; Rossi, M; Rossin, R; Roy, P; Ruiz, A; Russ, J; Rusu, V; Safonov, A; Sakumoto, W K; Salt, O; Santibb, L; Sarkaraa, S; Sartori, L; Sato, o K; Savoy-Navarro, A; Schlabach, P; Schmidt, A; Schmidt, E E; Schmidt, M A; Schmidt, M P; Schmitt, M; Schwarz, T; Scodellaro, L; Scribanoy, A; Scuri, F; Sedov, A; Seidel, S; Seiya, Y; Semenov, A; Sexton-Kennedy, L; Sforza, F; Sfyrla, A; Shalhout, S Z; Shears, T G; Shepard, P F; Shimojimap, M; Shiraishi, S; Shochet, M; Shon, Y; Shreyber, I; Sidoti, A; Sinervo, P; Sisakian, A; Slaughter, A J; Slaunwhite, J; Sliwa, K; Smith, J R; Snider, F D; Snihur, R; Soha, A; Somalwar, S; Sorin, V; Spalding, J; Spreitzer, T; Squillaciotiy, P; Stanitzki, M; Saint-Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Strycker, G L; Stuart, D; Suh, J S; Sukhanov, A; Suslov, I; Suzuki, T; Taffardf, A; Takashima, R; Takeuchi, Y; Tanaka, R; Tecchio, M; Teng, P K; Terashi, K; Thomh, J; Thompson, A S; Thompson, G A; Thomson, E; Tipton, P; Ttito-Guzmn, P; Tkaczyk, S; Toback, D; Tokar, a S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Totarobb, P; Tourneur, S; Trovato, M; Tsai, S Y; Tu, Y; Turiniy, N; Ukegawa, F; Vallecorsa, S; van Remortelb, N; Varganov, A; Vatagaz, E; Vazquezm, F; Velev, G; Vellidis, C; Veszpremi, V; Vidal, M; Vidal, R; Vila, I; Vilar, R; Vine, T; Vogel, M; Volobouevt, I; Volpix, G; Wagner, P; Wagner, R G; Wagner, R L; Wagner, W; Wagner-Kuhr, J; Wakisaka, T; Wallny, R; Wang, S M; Warburton, A; Waters, D; Weinberger, M; Weinelt, J; Wester, W C; Whitehouse, B; Whitesonf, D; Wicklund, A B; Wicklund, E; Wilbur, S; Williams, G; Williams, H H; Wilson, P; Winer, B L; Wittichh, P; Wolbers, S; Wolfe, C; Wright, T; Wu, X; Würthwein, F; Wynne, S M; Xie, S; Yagil, A; Yamamoto, K; Yamaoka, J; Yango, U K; Yang, Y C; Yao, W M; Yeh, G P; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanelloaa, L; Zanetti, A; Zhang, X; Zhengd, Y; Zucchelliv, S
2008-01-01
Fully reconstructed top-antitop-events are used to determine the fractions of right-handed and longitudinally polarized W bosons produced in top-quark decays. The helicity fractions are sensitive to the couplings and the Dirac structure of the Wtb vertex. This paper reports measurements of the W-boson helicity fractions from two different methods using data corresponding to an integrated luminosity of 1.9 fb-1 of proton-antiproton collisions collected by the CDF II detector operating at the Fermilab Tevatron.
The polarized structure function of the nucleons with a non-extensive statistical quark model
Trevisan, Luis A.; Mirez, Carlos
2013-05-01
We studied an application of nonextensive thermodynamics to describe the polarized structure function of nucleon, in a model where the usual Fermi-Dirac and Bose-Einstein energy distribution, often used in the statistical models, were replaced by the equivalent functions of the q-statistical. The parameters of the model are given by an effective temperature T, the q parameter (from Tsallis statistics), and the chemical potentials given by the corresponding up (u) and down (d) quark normalization in the nucleon and by Δu and Δd of the polarized functions.
Energy Technology Data Exchange (ETDEWEB)
Wicke, Daniel; /Wuppertal U., Dept. Math.
2009-08-01
The aim of particle physics is the understanding of elementary particles and their interactions. The current theory of elementary particle physics, the Standard Model, contains twelve different types of fermions which (neglecting gravity) interact through the gauge bosons of three forces. In addition a scalar particle, the Higgs boson, is needed for theoretical consistency. These few building blocks explain all experimental results found in the context of particle physics, so far. Nevertheless, it is believed that the Standard Model is only an approximation to a more complete theory. First of all the fourth known force, gravity, has withstood all attempts to be included until now. Furthermore, the Standard Model describes several features of the elementary particles like the existence of three families of fermions or the quantisation of charges, but does not explain these properties from underlying principles. Finally, the lightness of the Higgs boson needed to explain the symmetry breaking is difficult to maintain in the presence of expected corrections from gravity at high scales. This is the so called hierarchy problem. In addition astrophysical results indicate that the universe consists only to a very small fraction of matter described by the Standard Model. Large fractions of dark energy and dark matter are needed to describe the observations. Both do not have any correspondence in the Standard Model. Also the very small asymmetry between matter and anti-matter that results in the observed universe built of matter (and not of anti-matter) cannot be explained until now. It is thus an important task of experimental particle physics to test the predictions of the Standard Model to the best possible accuracy and to search for deviations pointing to necessary extensions or modifications of our current theoretical understanding. The top quark was predicted to exist by the Standard Model as the partner of the bottom quark. It was first observed in 1995 by the
Voutilainen, Mikko
2015-01-01
We summarize measurements of b and c jet production at the LHC, which are an important signature and background for decays of massive particles such as H-to-b-bbar. These include measurements of the inclusive and dijet production of heavy quark jets, b and c jets produced in association with vector bosons Z and W, and decays of boosted Z bosons into pairs of b-bbar. The current status of b tagging and b jet energy scale is also reviewed. These measurements test perturbative QCD in the four and five-flavor number schemes, and provide insight into the relative importance of heavy flavor production through flavor creation, flavor excitation and gluon splitting channels. The W+c measurement provides additionally a powerful way to probe the strange quark and antiquark sea in the proton. The recent studies looking separately at production of one and two b jets find generally good agreement with theory predictions for two b-jet production, while some discrepancies are observed for singly produced b jets, particularl...
Holographic quark-gluon plasmas at finite quark density
Energy Technology Data Exchange (ETDEWEB)
Bigazzi, F. [Dipartimento di Fisica e Astronomia, Universita di Firenze, Sesto Fiorentino (Firenze), Pisa (Italy); INFN, Sezione di Torino (Italy); Cotrone, A. [Dipartimento di Fisica, Universita di Torino (Italy); Mas, J. [Departamento de Fisica de Particulas, Universidade de Santiago de Compostela (Spain); Instituto Galego de Fisica de Altas Enerxias (IGFAE), Santiago de Compostela (Spain); Tarrio, J. [Institute for Theoretical Physics and Spinoza Institute, Universiteit Utrecht, 3584 CE, Utrecht (Netherlands); Mayerson, D. [Institute for Theoretical Physics, University of Amsterdam (Netherlands)
2012-07-15
Gravity solutions holographically dual to strongly coupled quark-gluon plasmas with non-zero quark density are reviewed. They are motivated by the urgency of finding novel tools to explore the phase diagram of QCD-like theories at finite chemical potential. After presenting the solutions and their regime of validity, some of their physical properties are discussed. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Quark-anti-quark potential in N = 4 SYM
Gromov, Nikolay; Levkovich-Maslyuk, Fedor
2016-12-01
We construct a closed system of equations describing the quark-anti-quark potential at any coupling in planar N = 4 supersymmetric Yang-Mills theory. It is based on the Quantum Spectral Curve method supplemented with a novel type of asymptotics. We present a high precision numerical solution reproducing the classical and one-loop string predictions very accurately. We also analytically compute the first 7 nontrivial orders of the weak coupling expansion.
Dirac Neutrinos and Dark Matter Stability from Lepton Quarticity
Chuliá, Salvador Centelles; Srivastava, Rahul; Valle, José W F
2016-01-01
We propose to relate dark matter stability to the possible Dirac nature of neutrinos. The idea is illustrated in a simple scheme where small Dirac neutrino masses arise from a type--I seesaw mechanism as a result of a $Z_4$ discrete lepton number symmetry. The latter implies the existence of a viable WIMP dark matter candidate, whose stability arises from the same symmetry which ensures the Diracness of neutrinos.
Integrated optical Dirac physics via inversion symmetry breaking
Collins, Matthew J.; Zhang, Fan; Bojko, Richard; Chrostowski, Lukas; Rechtsman, Mikael C.
2016-12-01
Graphene and boron nitride are two-dimensional materials whose atoms are arranged in a honeycomb lattice. Their unique properties arise because their electrons behave like relativistic particles (without and with mass, respectively)—namely, they obey the Dirac equation. Here, we use a photonic analog of boron nitride to observe Dirac physics in a silicon integrated optical platform. This will allow for photonic applications of Dirac dispersions (gapped and ungapped) to be realized in an on-chip, integrated nanophotonic platform.
Heavy quarks and CP: Moriond 1985
Energy Technology Data Exchange (ETDEWEB)
Bjorken, J.D.
1985-03-01
The presentations at the Fifth Moriond Workshop on Heavy Quarks, Flavor Mixing, and CP Violation (La Plagne, France, January 13-19, 1985) are summarized. The following topics are reviewed. What's New (beyond the top, top quarks, bottom quarks, charm quarks, strange quarks, and others); why is all this being done (strong interactions and hadron structure, and electroweak properties); and what next (facilities and can one see CP violation in the B-anti B system). 64 refs., 10 figs.
Structure of Nonlocal Vacuum Condensate of Quarks
Institute of Scientific and Technical Information of China (English)
周丽娟; 马维兴
2003-01-01
The Dyson-Schwinger formalism is used to derive a fully dressed quark propagator. By use of the derived form of the quark propagator, the structure of non-local quark vacuum condensate is studied, and the values of local quark vacuum condensate as well as quark gluon mixed condensate are calculated. The theoretical predictions are in good agreement with the empirical one used commonly in the literature.
The GridPP DIRAC project: Implementation of a multi-VO DIRAC service
Bauer, D.; Colling, D.; Currie, R.; Fayer, S.; Huffman, A.; Martyniak, J.; Rand, D.; Richards, A.
2015-12-01
The GridPP consortium provides computing support to many high energy physics projects in the UK. As part of this GridPP offers access to a large amount of highly distributed resources across the UK for multiple collaborations. The userbase supported by GridPP includes hundreds of users spanning multiple virtual organisations with many different computing requirements. In order to provide a common interface to these distributed a centralised DIRAC instance has been setup at Imperial College London. This paper describes the experiences learnt from deploying this DIRAC instance and the modifications that have made to support the GridPP use case.
Unpaired Dirac cones in photonic lattices and networks (Conference Presentation)
Chong, Yidong; Leykam, Daniel; Rechtsman, Mikael C.
2016-09-01
Unpaired Dirac cones are bandstructures with two bands crossing at a single point in the Brillouin zone. It is known that photonic bandstructures can exhibit pairs of Dirac cones, similar to graphene; unpaired cones, however, have not observed in photonics, and have been observed in condensed-matter systems only among topological insulator surface states. We show that unpaired Dirac cones occur in a 2D photonic lattice that is not the surface of a 3D system. These modes have unusual properties, including conical diffraction and antilocalization immune to short-range disorder, due to the absence of "intervalley" scattering between Dirac cones.
Orbital magnetization of interacting Dirac fermions in graphene
Yan, Xin-Zhong; Ting, C. S.
2017-09-01
We present a formalism to calculate the orbital magnetization of interacting Dirac fermions under a magnetic field. In this approach, the divergence difficulty is overcome with a special limit of the derivative of the thermodynamic potential with respect to the magnetic field. The formalism satisfies the particle-hole symmetry of the Dirac fermions system. We apply the formalism to the interacting Dirac fermions in graphene. The charge and spin orderings and the exchange interactions between all the Landau levels are taken into account by the mean-field theory. The results for the orbital magnetization of interacting Dirac fermions are compared with that of noninteracting cases.
Canonical conjugated Dirac equation in a curved space
Dzhunushaliev, Vladimir
2012-01-01
It is shown that the calculation of Dirac operator for the spherical coordinate system with spherical Dirac matrices and using the spin connection formalism is in the contradiction with the definition of standard Dirac operator in the spherical Minkowski coordinate system. It is shown that such contradiction one can avoid by introducing a canonical conjugated covariant derivative for the spinor field. The Dirac equation solution on the Reissner - Nordstr\\"om background is obtained. The solution describes a bound state of a charged particle.
Index theorem and universality properties of the low-lying eigenvalues of improved staggered quarks.
Follana, E; Hart, A; Davies, C T H
2004-12-10
We study various improved staggered quark Dirac operators on quenched gluon backgrounds in lattice QCD generated using a Symanzik-improved gluon action. We find a clear separation of the spectrum into would-be zero modes and others. The number of would-be zero modes depends on the topological charge as expected from the index theorem, and their chirality expectation value is large ( approximately 0.7). The remaining modes have low chirality and show clear signs of clustering into quartets and approaching the random matrix theory predictions for all topological charge sectors. We conclude that improvement of the fermionic and gauge actions moves the staggered quarks closer to the continuum limit where they respond correctly to QCD topology.
Unified description of quarks and leptons in a multi-spinor field formalism
Sogami, Ikuo S
2016-01-01
Multi-spinor fields which behave as triple-tensor products of the Dirac spinors and form reducible representations of the Lorentz group describe three families of ordinary quarks and leptons in the visible sector and an additional family of exotic dark quarks and leptons in the dark sector of the Universe. Apart from the ordinary set of the gauge and Higgs fields in the visible sector, another set of gauge and Higgs fields belonging to the dark sector are assumed to exist. Two sectors possess channels of communication through gravity and a bi-quadratic interaction between the two types of Higgs fields. A candidate for the main component of the dark matter is a stable dark hadron with spin 3/2, and the upper limit of its mass is estimated to be 15.1 GeV/c$^2$.
A Gauge and Lorentz covariant Approximation for the Quark Propagator in an arbitrary Gluon Field
Gromes, D
2001-01-01
We decompose the quark propagator in the presence of an arbitrary gluon field with respect to a set of Dirac matrices. The four-dimensional integrals which arise in first order perturbation theory are rewritten as line-integrals along certain field lines, together with a weighted integration over the various field lines. It is then easy to transform the propagator into a form involving path ordered exponentials. The resulting expression is non-perturbative and has the correct behavior under Lorentz transformations, gauge transformations and charge conjugation. Furthermore it coincides with the exact propagator in first order of the coupling g. No expansion with respect to the inverse quark mass is involved, the expression can even be used for vanishing mass. For large mass the field lines concentrate near the straight line connection and simple results can be obtained immediately.
A Gauge and Lorentz covariant approximation for the quark propagator in an arbitrary gluon field
Gromes, D.
2001-05-01
We decompose the quark propagator in the presence of an arbitrary gluon field with respect to a set of Dirac matrices. The four-dimensional integrals which arise in first order perturbation theory are rewritten as line-integrals along certain field lines, together with a weighted integration over the various field lines. It is then easy to transform the propagator into a form involving path ordered exponentials. The resulting expression is non-perturbative and has the correct behavior under Lorentz transformations, gauge transformations and charge conjugation. Furthermore it coincides with the exact propagator in first order of the coupling g. No expansion with respect to the inverse quark mass is involved, the expression can even be used for vanishing mass. For large mass the field lines concentrate near the straight line connection and simple results can be obtained immediately.
Masses and mixing matrices of quarks within the spin-charge-family theory
Bregar, Gregor
2012-01-01
The spin-charge-family theory predicts the number of families. There are four massless families of quarks and leptons before the electroweak break. There are two kinds of charges in this theory, connected with two kinds of the Clifford objects. The Dirac like kind explains the spin and the standard model charges, the second kind explains the existence of families. Correspondingly there are two kinds of scalar fields, determining masses of vector bosons and mass matrices of fermions. The first kind distinguishes only among family members, the second kind only among families. Mass matrices exhibit correspondingly very particular symmetries. In this contribution we take matrix elements as free parameters, which we determine by requiring that mass matrices keep by the spin-charge-family theory determined symmetries and that properties of fermions agree with the experimental data. Very preliminary results show that matrix elements of one of the two quark mass matrices are surprisingly close (within a factor of les...
Dumé, Belle
2003-01-01
"Physicists working at the Relativistic Heavy Ion Collider (RHIC) at the Brookhaven National Laboratory in the US say that they have come closer than ever before to creating a quark-gluon plasma" (0.5 page)
Quark Model and multiquark system
da Silva, Cristiane Oldoni
2010-01-01
The discovery of many particles, especially in the 50's, when the firsts accelerators appeared, caused the searching for a model that would describe in a simple form the whole of known particles. The Quark Model, based in the mathematical structures of group theory, provided in the beginning of the 60's a simplified description of hadronic matter already known, proposing that three particles, called quarks, would originate all the observed hadrons. This model was able to preview the existence of particles that were later detected, confirming its consistency. Extensions of the Quark Model were made in the beginning of the 70's, focusing in describing observed particles that were excited states of the fundamental particles and others that presented new quantum numbers (flavors). Recently, exotic states as tetraquarks and pentaquarks types, also called multiquarks systems, previewed by the model, were observed, what renewed the interest in the way as quarks are confined inside the hadrons. In this article we pre...
Abachi, S.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adam, I.; Adams, D. L.; Adams, M.; Ahn, S.; Aihara, H.; Alitti, J.; Álvarez, G.; Alves, G. A.; Amidi, E.; Amos, N.; Anderson, E. W.; Aronson, S. H.; Astur, R.; Avery, R. E.; Baden, A.; Balamurali, V.; Balderston, J.; Baldin, B.; Bantly, J.; Bartlett, J. F.; Bazizi, K.; Bendich, J.; Beri, S. B.; Bertram, I.; Bezzubov, V. A.; Bhat, P. C.; Bhatnagar, V.; Bhattacharjee, M.; Bischoff, A.; Biswas, N.; Blazey, G.; Blessing, S.; Boehnlein, A.; Bojko, N. I.; Borcherding, F.; Borders, J.; Boswell, C.; Brandt, A.; Brock, R.; Bross, A.; Buchholz, D.; Burtovoi, V. S.; Butler, J. M.; Casey, D.; Castilla-Valdez, H.; Chakraborty, D.; Chang, S.-M.; Chekulaev, S. V.; Chen, L.-P.; Chen, W.; Chevalier, L.; Chopra, S.; Choudhary, B. C.; Christenson, J. H.; Chung, M.; Claes, D.; Clark, A. R.; Cobau, W. G.; Cochran, J.; Cooper, W. E.; Cretsinger, C.; Cullen-Vidal, D.; Cummings, M.; Cutts, D.; Dahl, O. I.; de, K.; Demarteau, M.; Demina, R.; Denisenko, K.; Denisenko, N.; Denisov, D.; Denisov, S. P.; Dharmaratna, W.; Diehl, H. T.; Diesburg, M.; di Loreto, G.; Dixon, R.; Draper, P.; Drinkard, J.; Ducros, Y.; Dugad, S. R.; Durston-Johnson, S.; Edmunds, D.; Efimov, A. O.; Ellison, J.; Elvira, V. D.; Engelmann, R.; Eno, S.; Eppley, G.; Ermolov, P.; Eroshin, O. V.; Evdokimov, V. N.; Fahey, S.; Fahland, T.; Fatyga, M.; Fatyga, M. K.; Featherly, J.; Feher, S.; Fein, D.; Ferbel, T.; Finocchiaro, G.; Fisk, H. E.; Fisyak, Yu.; Flattum, E.; Forden, G. E.; Fortner, M.; Frame, K. C.; Franzini, P.; Fredriksen, S.; Fuess, S.; Galjaev, A. N.; Gallas, E.; Gao, C. S.; Gao, S.; Geld, T. L.; Genik, R. J., II; Genser, K.; Gerber, C. E.; Gibbard, B.; Glaubman, M.; Glebov, V.; Glenn, S.; Glicenstein, J. F.; Gobbi, B.; Goforth, M.; Goldschmidt, A.; Gomez, B.; Goncharov, P. I.; Gordon, H.; Goss, L. T.; Graf, N.; Grannis, P. D.; Green, D. R.; Green, J.; Greenlee, H.; Griffin, G.; Grossman, N.; Grudberg, P.; Grünendahl, S.; Guida, J. A.; Guida, J. M.; Guryn, W.; Gurzhiev, S. N.; Gutnikov, Y. E.; Hadley, N. J.; Haggerty, H.; Hagopian, S.; Hagopian, V.; Hahn, K. S.; Hall, R. E.; Hansen, S.; Hatcher, R.; Hauptman, J. M.; Hedin, D.; Heinson, A. P.; Heintz, U.; Hernandez-Montoya, R.; Heuring, T.; Hirosky, R.; Hobbs, J. D.; Hoeneisen, B.; Hoftun, J. S.; Hsieh, F.; Hu, Ting; Hu, Tong; Huehn, T.; Igarashi, S.; Ito, A. S.; James, E.; Jaques, J.; Jerger, S. A.; Jiang, J. Z.-Y.; Joffe-Minor, T.; Johari, H.; Johns, K.; Johnson, M.; Johnstad, H.; Jonckheere, A.; Jöstlein, H.; Jun, S. Y.; Jung, C. K.; Kahn, S.; Kang, J. S.; Kehoe, R.; Kelly, M.; Kernan, A.; Kerth, L.; Kim, C. L.; Kim, S. K.; Klatchko, A.; Klima, B.; Klochkov, B. I.; Klopfenstein, C.; Klyukhin, V. I.; Kochetkov, V. I.; Kohli, J. M.; Koltick, D.; Kostritskiy, A. V.; Kotcher, J.; Kourlas, J.; Kozelov, A. V.; Kozlovski, E. A.; Krishnaswamy, M. R.; Krzywdzinski, S.; Kunori, S.; Lami, S.; Landsberg, G.; Lanou, R. E.; Lebrat, J.-F.; Lee-Franzini, J.; Leflat, A.; Li, H.; Li, J.; Li, Y. K.; Li-Demarteau, Q. Z.; Lima, J. G.; Lincoln, D.; Linn, S. L.; Linnemann, J.; Lipton, R.; Liu, Y. C.; Lobkowicz, F.; Loken, S. C.; Lökös, S.; Lueking, L.; Lyon, A. L.; Maciel, A. K.; Madaras, R. J.; Madden, R.; Mandrichenko, I. V.; Mangeot, Ph.; Mani, S.; Mansoulié, B.; Mao, H. S.; Margulies, S.; Markeloff, R.; Markosky, L.; Marshall, T.; Martin, M. I.; Marx, M.; May, B.; Mayorov, A. A.; McCarthy, R.; McKibben, T.; McKinley, J.; Melanson, H. L.; de Mello Neto, J. R.; Merritt, K. W.; Miettinen, H.; Milder, A.; Milner, C.; Mincer, A.; de Miranda, J. M.; Mishra, C. S.; Mohammadi-Baarmand, M.; Mokhov, N.; Mondal, N. K.; Montgomery, H. E.; Mooney, P.; Mudan, M.; Murphy, C.; Murphy, C. T.; Nang, F.; Narain, M.; Narasimham, V. S.; Narayanan, A.; Neal, H. A.; Negret, J. P.; Neis, E.; Nemethy, P.; NešiĆ, D.; Norman, D.; Oesch, L.; Oguri, V.; Oltman, E.; Oshima, N.; Owen, D.; Padley, P.; Pang, M.; Para, A.; Park, C. H.; Park, Y. M.; Partridge, R.; Parua, N.; Paterno, M.; Perkins, J.; Peryshkin, A.; Peters, M.; Piekarz, H.; Pischalnikov, Y.; Pluquet, A.; Podstavkov, V. M.; Pope, B. G.; Prosper, H. B.; Protopopescu, S.; Pušeljić, D.; Qian, J.; Quintas, P. Z.; Raja, R.; Rajagopalan, S.; Ramirez, O.; Rao, M. V.; Rapidis, P. A.; Rasmussen, L.; Read, A. L.; Reucroft, S.; Rijssenbeek, M.; Rockwell, T.; Roe, N. A.; Roldan, J. M.; Rubinov, P.; Ruchti, R.; Rusin, S.; Rutherfoord, J.; Santoro, A.; Sawyer, L.; Schamberger, R. D.; Schellman, H.; Schmid, D.; Sculli, J.; Shabalina, E.; Shaffer, C.; Shankar, H. C.; Shivpuri, R. K.; Shupe, M.; Singh, J. B.; Sirotenko, V.; Smart, W.; Smith, A.; Smith, R. P.; Snihur, R.; Snow, G. R.; Snyder, S.; Solomon, J.; Sood, P. M.; Sosebee, M.; Souza, M.; Spadafora, A. L.; Stephens, R. W.; Stevenson, M. L.; Stewart, D.; Stocker, F.; Stoianova, D. A.; Stoker, D.; Streets, K.; Strovink, M.; Taketani, A.; Tamburello, P.; Tarazi, J.; Tartaglia, M.; Taylor, T. L.; Teiger, J.; Thompson, J.; Trippe, T. G.; Tuts, P. M.; Varelas, N.; Varnes, E. W.; Virador, P. R.; Vititoe, D.; Volkov, A. A.; von Goeler, E.; Vorobiev, A. P.; Wahl, H. D.; Wang, J.; Wang, L. Z.; Warchol, J.; Wayne, M.; Weerts, H.; Wenzel, W. A.; White, A.; White, J. T.; Wightman, J. A.; Wilcox, J.; Willis, S.; Wimpenny, S. J.; Wirjawan, J. V.; Wolf, Z.; Womersley, J.; Won, E.; Wood, D. R.; Xu, H.; Yamada, R.; Yamin, P.; Yanagisawa, C.; Yang, J.; Yasuda, T.; Yoshikawa, C.; Youssef, S.; Yu, J.; Yu, Y.; Zhang, Y.; Zhou, Y. H.; Zhu, Q.; Zhu, Y. S.; Zhu, Z. H.; Zieminska, D.; Zieminski, A.; Zinchenko, A.; Zylberstejn, A.
1995-04-01
The D0 Collaboration reports on a search for the standard model top quark in pp¯ collisions at s = 1.8 TeV at the Fermilab Tevatron with an integrated luminosity of approximately 50 pb-1. We have searched for tt¯ production in the dilepton and single-lepton decay channels with and without tagging of b-quark jets. We observed 17 events with an expected background of 3.8+/-0.6 events. The probability for an upward fluctuation of the background to produce the observed signal is 2×10-6 (equivalent to 4.6 standard deviations). The kinematic properties of the excess events are consistent with top quark decay. We conclude that we have observed the top quark and measured its mass to be 199+19-21 (stat) +/-22 (syst) GeV/c2 and its production cross section to be 6.4+/-2.2 pb.
Solid Bare Strange Quark Stars
Xu, R X
2003-01-01
The reason, we need three terms of `strange', `bare', and `solid' before quark stars, is presented concisely though some fundamental issues are not certain. Observations favoring these stars are introduced.
Top Quark Physics: Future Measurements
Energy Technology Data Exchange (ETDEWEB)
Jaros, John A
2003-05-09
We discuss the study of the top quark at future experiments and machines. Top's large mass makes it a unique probe of physics at the natural electroweak scale. We emphasize measurements of the top quark's mass, width, and couplings, as well as searches for rare or nonstandard decays, and discuss the complementary roles played by hadron and lepton colliders.
Stability of Quark Star Models
Azam, M.; Mardan, S. A.; Rehman, M. A.
2016-05-01
In this paper, we investigate the stability of quark stars with four different types of inner matter configurations; isotropic, charged isotropic, anisotropic and charged anisotropic by using the concept of cracking. For this purpose, we have applied local density perturbations technique to the hydrostatic equilibrium equation as well as on physical parameters involved in the model. We conclude that quark stars become potentially unstable when inner matter configuration is changed and electromagnetic field is applied.
Pourquoi les quarks restent invisibles
Gross, David J
2005-01-01
At the beginning of the seventies, physicists discovered a new scale in the matter structure. Protons and neutrons, components of the atomic nucleus, seemed to be constituted by even more elementar particles: the quarks. But while they seemed to move freely inside the protons, it was impossible to isolate one of these quarks. The Nobel Prize for physics rewarded the explanation of this phenomenon (3 pages)
Heavy quark production and spectroscopy
Energy Technology Data Exchange (ETDEWEB)
Appel, J.A.
1993-11-01
This review covers many new experimental results on heavy flavor production and spectroscopy. It also shows some of the increasingly improved theoretical understanding of results in light of basic perturbative QCD and heavy quark symmetry. At the same time, there are some remaining discrepancies among experiments as well as significant missing information on some of the anticipated lowest lying heavy quark states. Most interesting, perhaps, are some clearly measured production effects awaiting full explanation.
Deconfinement and virtual quark loops
Çelik, T.; Engels, J.; Satz, H.
1983-12-01
We calculate paer Monte Carlo evaluation on an 83 × 3 lattice the energy density ɛG of the gluon sector of QCD, including virtual quark loops up to the fourth power in the hopping parameter expansion. For light quarks of one flavour, we observe at T/ΛL 95 +/- 10 a rapid variation of ɛG in T, accompanied by strong fluctuations from iteration to iteration. as clear signal of the deconfinement transition.
THE DOUBLE COUPLING OF THE ASHTEKAR GRAVITATIONAL FIELD TO THE DIRAC SPINORAL FIELDS*
Institute of Scientific and Technical Information of China (English)
吴亚波; 桂元星
2001-01-01
By introducing the double spacetime manifold, the double gamma matrices and Dirac spinors, the action of theDirac spinoral fields is doubled. Furthermore, the double coupling of the Dirac fields to the Ashtekar gravitational fields is studied.
Polarization in heavy quark decays
Energy Technology Data Exchange (ETDEWEB)
Alimujiang, K.
2006-07-01
In this thesis I concentrate on the angular correlations in top quark decays and their next.to.leading order (NLO) QCD corrections. I also discuss the leading.order (LO) angular correlations in unpolarized and polarized hyperon decays. In the first part of the thesis I calculate the angular correlation between the top quark spin and the momentum of decay products in the rest frame decay of a polarized top quark into a charged Higgs boson and a bottom quark in Two-Higgs-Doublet-Models: t({up_arrow}) {yields} b + H{sup +}. I provide closed form formulae for the O({alpha}{sub s}) radiative corrections to the unpolarized and the polar correlation functions for m{sub b}{ne}0 and m{sub b}=0. In the second part I concentrate on the semileptonic rest frame decay of a polarized top quark into a bottom quark and a lepton pair: t({up_arrow}){yields}X{sub b}+l{sup +}+{nu}{sub l}. I present closed form expressions for the O({alpha}{sub s}) radiative corrections to the unpolarized part and the polar and azimuthal correlations for m{sub b}{ne}0 and m{sub b}=0. In the last part I turn to the angular distribution in semileptonic hyperon decays. Using the helicity method I derive complete formulas for the leading order joint angular decay distributions occurring in semileptonic hyperon decays including lepton mass and polarization effects. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Jung, A. W. [Fermilab
2014-09-24
Recent measurements of top-quark properties at the LHC and the Tevatron are presented. Most recent measurements of the top quark mass have been carried out by CMS using $19.7/$fb of $\\sqrt{s} = 8$ TeV data including the study of the dependence on event kinematics. ATLAS uses the full Run I data at $\\sqrt{s} = 7$ TeV for a "3D" measurement that significantly reduces systematic uncertainties. D0 employs the full Run II data using the matrix element method to measure the top quark mass with significantly reduced systematic uncertainties. Many different measurements of the top quark exist to date and the most precise ones per decay channel per experiment have been combined into the first world combination with a relative precision of 0.44%. Latest updates of measurements of production asymmetries include the measurement of the \\ttbar production asymmetry by D0 employing the full Run II data set, by CMS and ATLAS (including the polarization of the top quark) employing both the full data set at $\\sqrt{s} = 7$ TeV. CMS uses the full $\\sqrt{s} = 8$ TeV data to measure the top quark polarization in single top production, the ratio ${\\cal R}$ of the branching fractions ${\\cal B}(t \\rightarrow Wb) / {\\cal B}(t \\rightarrow Wq)$ and to search for flavor changing neutral currents. The results from all these measurements agree well with their respective Standard Model expectation.
Local moment formation in Dirac electrons
Mashkoori, M.; Mahyaeh, I.; Jafari, S. A.
2015-04-01
Elemental bismuth and its compounds host strong spin-orbit interaction which is at the heart of topologically non-trivial alloys based on bismuth. These class of materials are described in terms of 4x4 matrices at each v point where spin and orbital labels of the underlying electrons are mixed. In this work we investigate the single impurity Anderson model (SIAM) within a mean field approximation to address the nature of local magnetic moment formation in a generic Dirac Hamiltonian. Despite the spin-mixing in the Hamiltonian, within the Hartree approximation it turns out that the impuritys Green function is diagonal in spin label. In the three dimensional Dirac materials defined over a bandwidth D and spin-orbit parameter γ, that hybridizes with impurity through V, a natural dimensionless parameter V2D/2πγ3 emerges. So neither the hybridization strength, V, nor the spin-orbit coupling γ, but a combination thereof governs the phase diagram. By tuning chemical potential and the impurity level, we present phase diagram for various values of Hubbard U. Numerical results suggest that strong spin-orbit coupling enhances the local moment formation both in terms of its strength and the area of the local moment region. In the case that we tune the chemical potential in a similar way as normal metal we find that magnetic region is confined to μ ≥ ε0, in sharp contrast to 2D Dirac fermions. If one fixes the chemical potential and tunes the impurity level, phase diagram has two magnetic regions which corresponds to hybridization of impurity level with lower and upper bands.
Measurement of top quark properties at CMS
Piedra Gomez, Jonatan
2015-01-01
Measurements of top quark properties in top quark decays are presented, using data collected by the CMS experiment during the years 2011 and 2012. The polarization of W bosons in top quark decays is measured. The W boson helicity fractions and angular asymmetries are extracted, and limits on anomalous contributions to the Wtb vertex are determined. Furthermore, searches for flavor changing neutral currents in top quark decays are presented. The flavor contents in top quark pair events are measured using the fraction of top quarks decaying into a W boson and a b quark relative to all top quark decays, $R=BR({\\rm t} \\to {\\rm Wb})/BR({\\rm t} \\to {\\rm Wq})$, and the result is used to determine the CKM matrix element $V_{\\rm tb}$ as well as the width of the top quark resonance.
Dirac Phenomenology and Hyperon-Nucleus Interactions
J., MARES; B. K., JENNINGS; E. D., COOPER; Triumf, 4004 Wesbrook Mall; Department of Physics, University College of the Fraser Valley
1995-01-01
We discuss various aspects of hyperon-nucleus interactions in the relativistic mean field theory. First, characteristics of Λ, Σ and Ξ hypernuclei, as well as multi-strange baryonic objects, are investigated. The spin-orbit splittings and magnetic moments are shown to be very sensitive to the value of the tensor coupling f_. Second, optical potentials for Λ and Σ scattering off nuclei are developed based on a global nucleon-nucleus Dirac optical potential and SU(3) symmetry. The tensor coupli...
Dirac oscillator interacting with a topological defect
Energy Technology Data Exchange (ETDEWEB)
Carvalho, J.; Furtado, C.; Moraes, F. [Unidade Academica de Tecnologia de Alimentos, CCTA, Universidade Federal de Campina Grande, Pereiros, 58840-000, Pombal, Paraiba (Brazil); Departamento de Fisica, CCEN, Universidade Federal da Paraiba, Cidade Universitaria, 58051-970 Joao Pessoa, Paraiba (Brazil)
2011-09-15
In this work we study the interaction problem of a Dirac oscillator with gravitational fields produced by topological defects. The energy levels of the relativistic oscillator in the cosmic string and in the cosmic dislocation space-times are sensible to curvature and torsion associated to these defects and are important evidence of the influence of the topology on this system. In the presence of a localized magnetic field the energy levels acquire a term associated with the Aharonov-Bohm effect. We obtain the eigenfunctions and eigenvalues and see that in the nonrelativistic limit some results known in standard quantum mechanics are reached.
Dirac operator normality and chiral properties
Kerler, W.
Normality and γ5-hermiticity are what gives rise to chiral properties and rules. The Ginsparg-Wilson (GW) relation is only one of the possible spectral constraints. The sum rule for chiral differences of real modes has important consequences. The alternative transformation of Lüscher gives the same Ward identity as the usual chiral one (if zero modes are properly treated). Imposing normality on a general function of the hermitean Wilson-Dirac operator H leads at same time to the GW relation and to the Neuberger operator.
Locality properties of Neuberger's lattice Dirac operator
Hernández, Pilar; Jansen, Karl; Lüscher, Martin
1999-07-01
The gauge covariant lattice Dirac operator D which has recently been proposed by Neuberger satisfies the Ginsparg-Wilson relation and thus preserves chiral symmetry. The operator also avoids a doubling of fermion species, but its locality properties are not obvious. We now prove that D is local (with exponentially decaying tails) if the gauge field is sufficiently smooth at the scale of the cutoff. Further analytic and numerical studies moreover suggest that the locality of the operator is in fact guaranteed under far more general conditions.
Dirac equation and the Melvin metric
Energy Technology Data Exchange (ETDEWEB)
Santos, L.C.N.; Barros, C.C. [Universidade Federal de Santa Catarina, Depto de Fisica-CFM, CP. 476, Florianopolis, SC (Brazil)
2016-10-15
A relativistic wave equation for spin 1/2 particles in the Melvin space-time, a space-time where the metric is determined by a magnetic field, is obtained. The energy levels for these particles are obtained as functions of the magnetic field and compared with the ones calculated with the Dirac equation in the flat Minkowski space-time. The numeric values for some magnetic fields of interest are shown. With these results, the effects of very intense magnetic fields on the energy levels, as intense as the ones expected to be produced in magnetars or in ultra-relativistic heavy-ion collisions, are investigated. (orig.)
Third level trigger of the DIRAC experiment
Gallas-Torreira, M V
2002-01-01
A fast and complete programmable high level trigger processor for the DIRAC experiment at CERN was designed and arranged based on state-of- art field programmable gate array (FPGA) technology. The implemented logic was created from Monte Carlo simulation results and further checked with real experimental data. Correspondence between desired and implemented logic was proved previously by use of a complete digital pattern generator built also with FPGA technology. The resulting trigger processor provides a selection of charged particle pairs with a small relative momentum. (9 refs).
Dirac gauginos in general gauge mediation
Energy Technology Data Exchange (ETDEWEB)
Benakli, K. [Laboratoire de Physique Theorique et Hautes Energies, CNRS, UPMC Univ Paris 06, Boite 126, 4 place Jussieu, F-75252 Paris Cedex 05 (France)], E-mail: kbenakli@lpthe.jussieu.fr; Goodsell, M.D. [Laboratoire de Physique Theorique et Hautes Energies, CNRS, UPMC Univ Paris 06, Boite 126, 4 place Jussieu, F-75252 Paris Cedex 05 (France)], E-mail: goodsell@lpthe.jussieu.fr
2009-07-21
We extend the formulation by Meade, Seiberg and Shih of general gauge mediation of supersymmetry breaking to include Dirac masses for the gauginos. These appear through mixing of the visible sector gauginos with additional states in adjoint representations. We illustrate the method by reproducing the existing results in the literature for the gaugino and sfermion masses when preserving R-symmetry. We then explain how the generation of same sign masses for the two propagating degrees of freedom in the adjoint scalars can be achieved. We end by commenting on the use of the formalism for describing U(1) mixing.
Dirac gauginos, gauge mediation and unification
Energy Technology Data Exchange (ETDEWEB)
Benakli, K., E-mail: kbenakli@lpthe.jussieu.f [Laboratoire de Physique Theorique et Hautes Energies, CNRS, UPMC Univ. Paris 06 Boite 126, 4 Place Jussieu, 75252 Paris cedex 05 (France); Goodsell, M.D., E-mail: mark.goodsell@desy.d [Deutsches Elektronen-Synchrotron, DESY, Notkestrasse 85, 22607 Hamburg (Germany)
2010-11-21
We investigate the building of models with Dirac gauginos and perturbative gauge coupling unification. Here, in contrast to the MSSM, additional fields are required for unification, and these can naturally play the role of the messengers of supersymmetry breaking. We present a framework within which such models can be constructed, including the constraints that the messenger sector must satisfy; and the renormalisation group equations for the soft parameters, which differ from those of the MSSM. For illustration, we provide the spectrum at the electroweak scale for explicit models whose gauge couplings unify at the scale predicted by heterotic strings.
Dirac gauginos, gauge mediation and unification
Energy Technology Data Exchange (ETDEWEB)
Benakli, K. [UPMC Univ. Paris 06 (France). Laboratoire de Physique Theorique et Hautes Energies, CNRS; Goodsell, M.D. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2010-03-15
We investigate the building of models with Dirac gauginos and perturbative gauge coupling unification. Here, in contrast to the MSSM, additional fields are required for unification, and these can naturally play the role of the messengers of supersymmetry breaking. We present a framework within which such models can be constructed, including the constraints that the messenger sector must satisfy; and the renormalisation group equations for the soft parameters, which differ from those of the MSSM. For illustration, we provide the spectrum at the electroweak scale for explicit models whose gauge couplings unify at the scale predicted by heterotic strings. (orig.)
Natural Dirac Neutrinos from Warped Extra Dimension
Wu, Jackson M S
2010-01-01
Dirac neutrinos arising from gauged discrete symmetry \\`a la Krauss-Wilczek are implemented in the minimal custodial Randall-Sundrum model. In the case of a normal hierarchy, all lepton masses and mixing pattern can be naturally reproduced at the TeV scale set by the electroweak constraints, while simultanously satisfy bounds from lepton flavour violation. A nonzero neutrino mixing angle, $\\theta_{13}$, is generic in the scenario, as well as the existence of sub-TeV right-handed Kaluza-Klein neutrinos, which may be searched for at the LHC.
Up, down, strange and charm quark masses with Nf = 2+1+1 twisted mass lattice QCD
Carrasco, N; Dimopoulos, P; Frezzotti, R; Gimenez, V; Herdoiza, G; Lami, P; Lubicz, V; Palao, D; Picca, E; Recker, S; Riggio, L; Rossi, G C; Sanfilippo, F; Scorzato, L; Simula, S; Tarantino, C; Urbach, C; Wenger, U
2014-01-01
We present a lattice QCD calculation of the up, down, strange and charm quark masses performed using the gauge configurations produced by the European Twisted Mass Collaboration with Nf = 2 + 1 + 1 dynamical quarks, which include in the sea, besides two light mass degenerate quarks, also the strange and charm quarks with masses close to their physical values. The simulations are based on a unitary setup for the two light quarks and on a mixed action approach for the strange and charm quarks. The analysis uses data at three values of the lattice spacing and pion masses in the range 210 - 450 MeV, allowing for accurate continuum limit and controlled chiral extrapolation. The quark mass renormalization is carried out non-perturbatively using the RI-MOM method. The results for the quark masses converted to the bar{MS} scheme are: mud(2 GeV) = 3.70(17) MeV, ms(2 GeV) = 99.6(4.1) MeV and mc(mc) = 1.348(42) GeV. We obtain also the quark mass ratios ms/mud = 26.66(32) and mc/ms = 11.62(16). By studying the mass split...
Up, down, strange and charm quark masses with Nf=2+1+1 twisted mass lattice QCD
Directory of Open Access Journals (Sweden)
N. Carrasco
2014-10-01
Full Text Available We present a lattice QCD calculation of the up, down, strange and charm quark masses performed using the gauge configurations produced by the European Twisted Mass Collaboration with Nf=2+1+1 dynamical quarks, which include in the sea, besides two light mass degenerate quarks, also the strange and charm quarks with masses close to their physical values. The simulations are based on a unitary setup for the two light quarks and on a mixed action approach for the strange and charm quarks. The analysis uses data at three values of the lattice spacing and pion masses in the range 210–450 MeV, allowing for accurate continuum limit and controlled chiral extrapolation. The quark mass renormalization is carried out non-perturbatively using the RI′-MOM method. The results for the quark masses converted to the MS¯ scheme are: mud(2 GeV=3.70(17 MeV, ms(2 GeV=99.6(4.3 MeV and mc(mc=1.348(46 GeV. We obtain also the quark mass ratios ms/mud=26.66(32 and mc/ms=11.62(16. By studying the mass splitting between the neutral and charged kaons and using available lattice results for the electromagnetic contributions, we evaluate mu/md=0.470(56, leading to mu=2.36(24 MeV and md=5.03(26 MeV.
AUTHOR|(SzGeCERN)655637
The measurement of prompt photon associated with a b jet in proton-proton interactions can provide us insight into the inner structure of proton. This is because precision of determination of parton distribution functions of b quark and gluon can be increased by such a measurement. The measurement of cross-section of prompt photon associated with a b jet (process $pp\\longrightarrow \\gamma + b + X$) at $\\sqrt{s}$= 8 TeV with the ATLAS detector is presented. Full 8 TeV dataset collected by ATLAS during the year 2012 was used in this analysis. Corresponding integrated luminosity is 20.3 $fb^{-1}$. Fiducial differential cross-section as a function of photon transverse momentum at particle level was extracted from data and compared with the prediction of leading order event generator Pythia 8. Cross-section extracted from data is normalised independently on the Monte Carlo prediction. Values of data distribution lie above Monte Carlo values. The difference can be explained by presence of higher order effects not ...
Strange Quark Matter Status and Prospects
Sandweiss, J.
2004-01-01
The existence of quark states with more than three quarks is allowed in QCD. The stability of such quark matter states has been studied with lattice QCD and phenomenological bag models, but is not well constrained by theory. The addition of strange quarks to the system allows the quarks to be in lower energy states despite the additional mass penalty. There is additional stability from reduced Coulomb repulsion. SQM is expected to have a low Z/A. Stable or metastable massive multiquark states contain u, d, and s quarks.
Selected top quark mass measurements at CMS
Bouvier, Elvire
2016-01-01
Selected measurements of the top quark mass are presented, obtained from CMS data collected in proton-proton collisions at the LHC at center-of-mass energies of 7, 8, and 13 TeV. ``Standard'' techniques are employed in each decay channel of top quark pair events and their results are combined. The mass of the top quark is also measured using several ``alternative'' methods, including measurements from shapes of top quark decay distributions in single top quark and top quark pair events as well as pole mass measurements.
Propagators and Masses of Light Quarks
Institute of Scientific and Technical Information of China (English)
ZHOU Li-Juan; ZHU Ji-Zhen; MA Wei-Xing
2003-01-01
Based on Dyson-Schwinger equations in "rainbow" approximation, fully dressed confining quark propagator is obtained, and then the masses of light quarks (mu, md, and ms) are derived from the fully dressed confining quark propagator. At the same time, the local and non-local quark vacuum condensates as well as the quark-gluon mixed condensate are also predicted. Furthermore, the quark masses are also deduced from the Gell-Mann-Oakes-Renner relation and chiral perturbative theory. The results from different methods are consistent with each other.
Propagators and Masses of Light Quarks
Institute of Scientific and Technical Information of China (English)
ZHOULi-Juan; ZHUJi-Zhen; MAWei-Xing
2003-01-01
Based on Dyson-Schwinger equations in “rainbow” approximation, fully dressed confining quark propagator is obtained, and then the masses of light quarks (mu, md, and ms) are derived from the fully dressed confining quark propagator. At the same time, the local and non-local quark vacuum condensates as well as the quark-gluon mixed condensate are also predicted. Furthermore, the quark masses are also deduced from the Gell-Mann-Oakes-Renner relation and chiral perturbative theory. The results from different methods are consistent with each other.
Simple Evaluation of Chiral Jacobian with Overlap Dirac Operator
Suzuki, H
1999-01-01
The chiral Jacobian, which is defined with Neuberger's overlap Dirac operator of lattice fermion, is explicitly evaluated in the continuum limit without expanding it in the gauge coupling constant. Our calculational scheme is simple and straightforward. We determine a coefficient of the chiral anomaly for general value of the bare mass parameter and the Wilson parameter of the overlap Dirac operator.
Dirac spinor in a nonstationary Godel-type cosmological Universe
Villalba, Victor M
2015-01-01
In the present article we solve, via separation of variables, the massless Dirac equation in a nonstationary rotating, causal G\\"odel-type cosmological universe, having a constant rotational speed in all the points of the space. We compute the frequency spectrum. We show that the spectrum of massless Dirac particles is discrete and unbounded.
Light scattering by photonic crystals with a dirac spectrum
Sepkhanov, Ruslan
2009-01-01
In this thesis we consider several effects of a Dirac spectrum in photonic crystals on the scattering and propagation of light. We calculate the effect of a Dirac point (a conical singularity in the band structure) on the transmission of radiation through a photonic crystal. We find that the transmi
NEW KINDS OF DIRAC ENERGY LEVELS AND THEIR CROSSING REGIONS
Institute of Scientific and Technical Information of China (English)
杨树政; 林理彬
2001-01-01
In the space-time of a non-Kerr-Newman black hole, the Dirac energy levels and their crossing regions are inves-tigated. Near the event horizon of the black hole there are crossing Dirac energy levels, which lead to the occurrence of non-thermal radiation.
Tools for analysis of Dirac structures on banach spaces
Iftime, Orest V.; Sandovici, Adrian; Golo, Goran
2005-01-01
Power-conserving and Dirac structures are known as an approach to mathematical modeling of physical engineering systems. In this paper connections between Dirac structures and well known tools from standard functional analysis are presented. The analysis can be seen as a possible starting framework
Wigner function for the Dirac oscillator in spinor space
Institute of Scientific and Technical Information of China (English)
马凯; 王剑华; 袁毅
2011-01-01
The Wigner function for the Dirac oscillator in spinor space is studied in this paper. Firstly, since the Dirac equation is described as a matrix equation in phase space, it is necessary to define the Wigner function as a matrix function in spinor space.
Algebraic and analytic Dirac induction for graded affine Hecke algebras
Ciubotaru, D.; Opdam, E.M.; Trapa, P.E.
2014-01-01
We define the algebraic Dirac induction map IndD for graded affine Hecke algebras. The map IndD is a Hecke algebra analog of the explicit realization of the Baum-Connes assembly map in the K-theory of the reduced C∗-algebra of a real reductive group using Dirac operators. The definition of IndD is