Momentum transport of chiral modes in a thermal QCD medium

TL;DR

This paper studies how a weak magnetic field influences momentum transport in a thermal QCD medium, revealing tensorial shear and bulk viscous coefficients that differ for chiral modes and depend on magnetic field strength and baryon asymmetry.

Contribution

It introduces a detailed analysis of tensorial momentum transport coefficients in a magnetic field, highlighting chiral mode differences and the impact of baryon asymmetry.

Findings

Shear and bulk viscous coefficients depend on magnetic field and chiral mode.

Magnetic field removes degeneracy in quark effective masses for L and R modes.

Viscous coefficients increase with baryon asymmetry.

Abstract

We have investigated the effect of a weak magnetic field on momentum transport in a thermal QCD medium at finite quark chemical potential using a semiclassical kinetic theory. In the presence of a magnetic field, the momentum transport coefficients acquire a tensor structure, reflected by the five shear $\left(\eta_0, \eta_1, \eta_2, \eta_3\right.$ and $\left.\eta_4\right)$ and two bulk viscous components $\left(\zeta_0\right.$ and $\left. \zeta_1\right)$. The weak magnetic field removes the degeneracy in the effective mass of flavours, leading to different masses for the left-handed (L) and right-handed (R) chiral modes of quarks. The coefficients, $\eta_0, \eta_1$ and $\eta_3$ decrease with magnetic field in L mode and increase in $\mathrm{R}$ mode, whereas, $\eta_2$ and $\eta_4$ increase in both L and $\mathrm{R}$ mode. The bulk viscous coefficients, $\zeta_0$ and $\zeta_1$ increase with magnetic field for both L and R mode. The shear and bulk viscous coefficients positively amplify with baryon asymmetry.