Thermal Relaxation, Electrical Conductivity and Charge Diffusion in a Hot QCD Medium

TL;DR

This paper investigates how electromagnetic fields interact with the quark-gluon plasma in heavy-ion collisions by analyzing temperature-dependent charge transport coefficients, using relativistic transport equations and effective QCD models.

Contribution

It introduces a comprehensive analysis of electrical conductivity and charge diffusion in hot QCD media, incorporating thermal relaxation times and effective fugacities with both perturbative and lattice QCD equations of state.

Findings

Transport coefficients are significantly affected by hot QCD medium effects.

Thermal relaxation times for quarks and gluons are quantitatively estimated.

Both perturbative and lattice QCD EOSs influence the temperature dependence of transport parameters.

Abstract

The response of electromagnetic (EM) fields that are produced in non-central heavy-ion collisions to electromagnetically charged quark gluon plasma can be understood in terms of charge transport and charge diffusion in the hot QCD medium. This article presents a perspective on these processes by investigating the temperature behavior of the related transport coefficients, {\it viz.} electrical conductivity and the charge diffusion coefficients along with charge susceptibility. In the process of estimating them, thermal relaxation times for quarks and gluons have been determined first. These transport coefficients have been studied by solving the relativistic transport equation in the Chapman-Enskog method. For the analysis, $2\rightarrow 2$, quark-quark, quark-gluon and gluon-gluon scattering processes are taken into account along with an effective description of hot QCD Equations of state (EOSs) in terms of temperature dependent effective fugacities of quasi-quarks (anti-quarks) and quasi-gluons. Both improved perturbative hot QCD EOSs at high temperature and a lattice QCD EOS are included for the analysis. The hot QCD medium effects entering through the quasi-particle momentum distributions along with an effective coupling, are seen to have significant impact on the temperature behavior of these transport parameters along with the thermal relaxation times for the quasi-gluons and quasi-quarks