Scattering of Quark-Quasiparticles in the Quark-Gluon Plasma (original) (raw)

Hadronic modes and quark properties in the quark-gluon plasma

Physical Review C, 2005

Based on interaction potentials between a heavy quark and antiquark as extracted from recent QCD lattice calculations, we set up a Brueckner-type many-body scheme to study the properties of light (anti-) quarks in a Quark-Gluon Plasma at moderate temperatures, T ≃ 1-2 T c . The quark-antiquark T -matrix, including both color-singlet and -octet channels, and corresponding quark self-energies and spectral functions are calculated self-consistently. The repulsive octet potential induces quasiparticle masses of up to 150 MeV, whereas the attractive color-singlet part generates resonance structures in the q-q T -matrix, which in turn lead to quasiparticle widths of ∼200 MeV. This corresponds to scattering rates of ∼1 fm −1 and may reflect liquid-like properties of the system. PACS numbers: 25.75.-q, 25.75.Dw, 25.75.Nq

Towards the dynamical study of heavy-flavor quarks in the Quark-Gluon-Plasma

Journal of Physics Conference Series

Within the aim of a dynamical study of on- and off-shell heavy quarks Q in the quark gluon plasma (QGP) - as produced in relativistic nucleus-nucleus collisions - we study the heavy quark collisional scattering on partons of the QGP. The elastic cross sections sigmaq,g−Q\sigma_{q,g-Q}sigmaq,g−Q are evaluated for perturbative partons (massless on-shell particles) and for dynamical quasi-particles (massive off-shell particles as described by the dynamical quasi-particles model "DQPM") using the leading order Born diagrams. We demonstrate that the finite width of the quasi-particles in the DQPM has little influence on the cross sections sigmaq,g−Q\sigma_{q,g-Q}sigmaq,g−Q except close to thresholds. We, furthermore, calculate the heavy quark relaxation time as a function of temperature T within the different approaches using these cross sections.

Spectral Properties of Quarks in the Quark-Gluon Plasma

Proceedings of The XXV International Symposium on Lattice Field Theory — PoS(LATTICE 2007), 2008

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 κ 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 κ. 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.

Thermodynamics and statistical physics of quasiparticles within the quark-gluon plasma model

2020

We consider thermodynamic properties of a quark-gluon plasma related to quasiparticles having the internal structure. For this purpose, we employ a possible analogy between quantum chromodynamics and non-Abelian Proca-Dirac-Higgs theory. The influence of characteristic sizes of the quasiparticles on such thermodynamic properties of the quark-gluon plasma like the internal energy and pressure is studied. Sizes of the quasiparticles are taken into account in the spirit of the van der Waals equation but we take into consideration that the quasiparticles have different sizes, and the average value of these sizes depends on temperature. It is shown that this results in a change in the internal energy and pressure of the quark-gluon plasma. Also, we show that, when the temperature increases, the average value of characteristic sizes of the quasiparticles increases as well. This leads to the occurrence of a phase transition at the temperature at which the volume occupied by the quasipartic...

Quantum and classical dynamics of heavy quarks in a quark-gluon plasma

Journal of High Energy Physics, 2018

We derive equations for the time evolution of the reduced density matrix of a collection of heavy quarks and antiquarks immersed in a quark gluon plasma. These equations, in their original form, rely on two approximations: the weak coupling between the heavy quarks and the plasma, the fast response of the plasma to the perturbation caused by the heavy quarks. An additional semi-classical approximation is performed. This allows us to recover results previously obtained for the abelian plasma using the influence functional formalism. In the case of QCD, specific features of the color dynamics make the implementation of the semi-classical approximation more involved. We explore two approximate strategies to solve numerically the resulting equations in the case of a quark-antiquark pair. One involves Langevin equations with additional random color forces, the other treats the transition between the singlet and octet color configurations as collisions in a Boltzmann equation which can be...

On the fate of quarkonia in quark gluon plasma medium within a Quasi-particle model

2019

We work on equations of state for hot QCD obtained from a hard thermal loop expression for the gluon self-energy, by employing the quasi-parton equilibrium distribution functions. The method involves mapping the interaction part of the equation of state to an effective fugacity of otherwise non-interacting quasi-gluons. Using the quasi-gluon distribution function, we have studied the dissociation of heavy Quarkonium in hot QCD medium by investigating the medium modification to a heavy quark potential. Employing the in-medium (corrected) potential while considering the anisotropy (both oblate and prolate cases) in the medium, the thermal widths and the binding energies of the heavy quarkonia states (s-wave charmonia and s-wave bottomonia specifically, for radial quantum numbers n=1 and 2) have been determined. In the present article, we shall consider an anisotropic QGP medium which is described in terms of quasi-particle degree of freedom based on a recent proposed quasiparticle mod...

Properties of the quark‐gluon plasma created in heavy‐ion collisions

Astronomische Nachrichten, 2021

We review the properties of the strongly interacting quark‐gluon plasma (QGP) at finite temperature and baryon chemical potential as created in heavy‐ion collisions at ultrarelativistic energies. The description of the strongly interacting (non‐perturbative) QGP in equilibrium is based on the effective propagators and couplings from the Dynamical QuasiParticle Model (DQPM) that is matched to reproduce the equation‐of‐state of the partonic system above the deconfinement temperature from lattice QCD. Based on a microscopic transport description of heavy‐ion collisions, we discuss which observables are sensitive to the QGP creation and its properties.

Quantum simulations of strongly coupled quark-gluon plasma

Physics of Atomic Nuclei, 2011

A strongly coupled quark-gluon plasma (QGP) of heavy constituent quasi-particles is studied by a path-integral Monte-Carlo method. This approach is a quantum generalization of the classical molecular dynamics by Gelman, Shuryak, and Zahed. It is shown that this method is able to reproduce the QCD lattice equation of state. The results indicate that the QGP reveals liquid-like rather than gaslike properties. Quantum effects turned out to be of prime importance in these simulations.

Widths of quarkonia in quark gluon plasma

Physical Review C, 2007

Recent lattice calculations showed that heavy quarkonia will survive beyond the phase transition temperature, and will dissolve at different temperatures depending on the type of the quarkonium. In this work, we calculate the thermal width of a quarkonium at finite temperature before it dissolves into open heavy quarks. The input of the calculation are the parton quarkonium dissociation cross section to NLO in QCD, the quarkonium wave function in a temperature-dependent potential from lattice QCD, and a thermal distribution of partons with thermal masses. We find that for the J/ψ, the total thermal width above 1.4 Tc becomes larger than 100 to 250 MeV, depending on the effective thermal masses of the quark and gluon, which we take between 400 to 600 MeV. Such a width corresponds to an effective dissociation cross section by gluons between 1.5 to 3.5 mb and by quarks 1 to 2 mb at 1.4 Tc. However, at similar temperatures, we find a much smaller thermal width and effective cross section for the Υ.