Nuclear Theory·nucl-th

Wednesday·October 12, 2016

9 papers—3 primary·6 cross-listed

01
Dissociation of heavy quarkonium in hot QCD medium in a quasi-particle model
Vineet K. Agotiya🇮🇳 · Vinod Chandra🇮🇳 · M. Yousuf Jamal🇮🇳 · Indrani Nilima🇮🇳
Following a recent work on the effective description of the equations of state for hot QCD obtained from a Hard thermal loop expression for the gluon self-energy, in terms of the quasi-gluons and quasi- quark/anti-quarks with respective effective fugacities, the dissociation process of heavy quarkonium in hot QCD medium has been investigated. This has been done by investigating the medium modification to a heavy quark potential. The medium modified potential has a quite different form (a long range Coulomb tail in addition to the usual Yukawa term) in contrast to the usual picture of Debye screening. The flavor dependence of the binding energies of the heavy quarkonia states and the dissociation temperature have been obtained by employing the debye mass for pure gluonic and full QCD case computed employing the quasi-particle picture. Thus estimated dissociation patterns of the charmonium and bottomonium states, considering Debye mass from different approaches in pure gluonic case and full QCD, have shown good agreement with the other potential model studies.
nucl-thPRD(2016)·57 citations
02
Collision energy dependence of elliptic flow splitting between particles and their antiparticles from an extended multiphase transport model
Jun Xu🇨🇳 · Che Ming Ko🇺🇸
Based on an extended multiphase transport model, which includes mean-field potentials in both the partonic and hadronic phases, uses the mix-event coalescence, and respects charge conservation during the hadronic evolution, we have studied the collision energy dependence of the elliptic flow splitting between particles and their antiparticles. This extended transport model reproduces reasonably well the experimental data at lower collision energies but only describes qualitatively the elliptic flow splitting at higher beam energies. The present study thus indicates the existence of other mechanisms for the elliptic flow splitting besides the mean-field potentials and the need of further improvements of the multiphase transport model.
nucl-thhep-exnucl-exPRC(2016)·20 citations
03
Separate chemical freeze-outs of strange and non-strange hadrons and problem of residual chemical non-equilibrium of strangeness in relativistic heavy ion collisions
K.A. Bugaev🇺🇦 · D.R. Oliinychenko🇺🇦 · V.V. Sagun🇺🇦 · A.I. Ivanytskyi🇺🇦 · J. Cleymans🇿🇦 · E.S. Mironchuk🇷🇺 · E.G. Nikonov🇷🇺 · A.V. Taranenko🇷🇺 · G.M. Zinovjev🇺🇦
We present an elaborate version of the hadron resonance gas model with the combined treatment of separate chemical freeze-outs for strange and non-strange hadrons and with an additional $γ_{s}$ factor which accounts for the remaining strange particle non-equilibration. Within suggested approach the parameters of two chemical freeze-outs are connected by the conservation laws of entropy, baryonic charge, third isospin projection and strangeness. The developed model enables us to perform a high-quality fit of the hadron multiplicity ratios measured at AGS, SPS and RHIC with $χ^{2} / d o f ≃ 0.93$ . A special attention is paid to a successful description of the Strangeness Horn. The well-known problem of selective suppression of $Λ ˉ$ and $Ξ ˉ$ hyperons is also discussed. The main result is that for all collision energies the $γ_{s}$ factor is about 1 within the error bars, except for the center of mass collision energy 7.6 GeV at which we find about 20\% enhancement of strangeness. Also we confirm an existence of strong jumps in pressure, temperature and effective number of degrees of freedom at the stage of strange particle chemical freeze-out, when the center of mass collision energy changes from 4.3 to 4.9 GeV. We argue that these irregularities may signal about the quark-hadron phase transition.
nucl-thUkr.J.Phys.(2016)·8 citations
04
Strongly interacting matter from holographic QCD model
Yidian Chen🇨🇳 · Danning Li🇨🇳 · Mei Huang🇨🇳
We introduce the 5-dimension dynamical holographic QCD model, which is constructed in the graviton-dilaton-scalar framework with the dilaton background field $Φ$ and the scalar field $X$ responsible for the gluodynamics and chiral dynamics, respectively. We review our results on the hadron spectra including the glueball and light meson spectra, QCD phase transitions and transport properties in the framework of the dynamical holographic QCD model.
↳ hep-phhep-lathep-thnucl-thEPJ Web Conf.(2016)·1 citation
05
Resonance poles and threshold energies for hadron physical problems by a model-independent universal algorithm
Ralf-Arno Tripolt🇮🇹 · Idan Haritan🇮🇱 · Jochen Wambach🇮🇹 · Nimrod Moiseyev🇮🇱
We show how complex resonance poles and threshold energies for systems in hadron physics can be accurately obtained by using a method based on the Padé-approximant which was recently developed for the calculation of resonance poles for atomic and molecular auto-ionization systems. The main advantage of this method is the ability to calculate the resonance poles and threshold energies from \emph{real} spectral data. In order to demonstrate the capabilities of this method we apply it here to an analytical model as well as to experimental data for the squared modulus of the vector pion form factor, the S0 partial wave amplitude for $π π$ scattering and the cross section ratio $R (s)$ for $e^{+} e^{-}$ collisions. The extracted values for the resonance poles of the $ρ (770)$ and the $f_{0} (500)$ or $σ$ meson are in very good agreement with the literature. When the data are noisy the prediction of decay thresholds proves to be less accurate but feasible.
↳ hep-phnucl-thPLB(2017)·76 citations
06
Strange quark asymmetry in the proton in chiral effective theory
X.G. Wang🇦🇺 · Chueng-Ryong Ji🇺🇸 · W. Melnitchouk🇺🇸 · Y. Salamu🇨🇳 · A.W. Thomas🇦🇺 · P. Wang🇨🇳
We perform a comprehensive analysis of the strange-antistrange parton distribution function (PDF) asymmetry in the proton in the framework of chiral effective theory, including the full set of lowest order kaon loop diagrams with off-shell and contact interactions, in addition to the usual on-shell contributions previously discussed in the literature. We identify the presence of $δ$ -function contributions to the $s ˉ$ PDF at $x = 0$ , with a corresponding valence-like component of the $s$ -quark PDF at larger $x$ , which allows greater flexibility for the shape of $s - s ˉ$ . Expanding the moments of the PDFs in terms of the pseudoscalar kaon mass, we compute the leading nonanalytic behavior of the number and momentum integrals of the $s$ and $s ˉ$ distributions, consistent with the chiral symmetry of QCD. We discuss the implications of our results for the understanding of the NuTeV anomaly and for the phenomenology of strange quark PDFs in global QCD analysis.
↳ hep-phhep-exnucl-thPRD(2016)·37 citations
07
Across the deconfinement
Claudio Bonati🇮🇹 · Massimo D'Elia🇮🇹 · Marco Mariti🇮🇹 · Michele Mesiti🇮🇹 · Francesco Negro🇮🇹 · Francesco Sanfilippo🇬🇧
The deconfinement transition at vanishing chemical potential can be reliably studied by lattice simulations and its general features are by now well known. On the contrary, what happens at finite density is still largely unknown and we will review the results obtained in the last year regarding the dependence, for small density, of the (pseudo)critical temperature on the baryonic chemical potential.
↳ hep-lathep-phhep-thnucl-thActa Phys.Polon.Supp.(2017)·3 citations
08
Equations of state for supernovae and compact stars
M. Oertel🇫🇷 · M. Hempel🇨🇭 · T. Klähn🇵🇱 · S. Typel🇩🇪
We review various theoretical approaches for the equation of state (EoS) of dense matter, relevant for the description of core-collapse supernovae, compact stars and compact star mergers. The emphasis is put on models that are applicable to all of these scenarios. Such EoS models have to cover large ranges in baryon number density, temperature and isospin asymmetry. The characteristics of matter change dramatically within these ranges, from a mixture of nucleons, nuclei, and electrons to uniform, strongly interacting matter containing nucleons, and possibly other particles such as hyperons or quarks. As the development of an EoS requires joint efforts from many directions we consider different theoretical approaches and discuss relevant experimental and observational constraints which provide insights for future research. Finally, results from applications of the discussed EoS models are summarized.
↳ astro-ph.HEastro-ph.SRnucl-thRMP(2017)·1260 citations
09
High Energy QCD at NLO: from light-cone wave function to JIMWLK evolution
Michael Lublinsky🇮🇱 · Yair Mulian🇮🇱
Soft components of the light cone wave-function of a fast moving projectile hadron is computed in perturbation theory to third order in QCD coupling constant. At this order, the Fock space of the soft modes consists of one-gluon, two-gluon, and a quark-antiquark states. The hard component of the wave-function acts as a non-Abelian background field for the soft modes and is represented by a valence charge distribution that accounts for non-linear density effects in the projectile. When scattered off a dense target, the diagonal element of the S-matrix reveals the Hamiltonian of high energy evolution, the JIMWLK Hamiltonian. This way we provide a new direct derivation of the JIMWLK Hamiltonian at the Next-to-Leading Order.
↳ hep-phhep-thnucl-thJHEP(2017)·82 citations

Affiliations

first authorsco-authorsvia INSPIRE