Bulk viscosity of a hot QCD/QGP medium in strong magnetic field within relaxation-time approximation

TL;DR

This paper calculates the bulk viscosity of hot QCD/QGP in a strong magnetic field using kinetic theory and relaxation-time approximation, highlighting its temperature dependence near the transition point.

Contribution

It introduces a novel estimation of quark damping rates and bulk viscosity in strong magnetic fields within an effective kinetic theory framework.

Findings

Bulk viscosity increases near the transition temperature.

Dominant process is $g ightarrow q ar{q}$ in strong magnetic fields.

Bulk viscosity to entropy density ratio rises near the transition.

Abstract

The bulk viscosity of hot QCD medium has been obtained in the presence of strong magnetic field. The present investigation involves the estimation of the quark damping rate and subsequently the thermal relaxation time for quarks in the presence of magnetic field while realizing the hot QCD medium as an effective Grand-canonical ensemble of effective gluons and quarks-antiquarks. The dominant process in the strong field limit is $1\rightarrow 2$ ($g\rightarrow q \bar{q}$) which contributes to the bulk viscosity in a most significant way. Further, setting up the linearized transport equation in the framework of an effective kinetic theory with hot QCD medium effects and employing the relaxation time approximation, the bulk viscosity has been estimated in lowest Landau level (LLL) and beyond. The temperature dependence of the ratio of the bulk viscosity to entropy density indicates towards its rising behavior near the transition temperature.