Shear Viscosity of a Quark Plasma Near the Chiral Phase Transition

TL;DR

This paper calculates the shear viscosity of a quark plasma near the chiral phase transition using the NJL model, revealing how viscosity varies with temperature and chemical potential.

Contribution

It provides a leading-order calculation of shear viscosity in a quark plasma near the chiral transition, incorporating finite temperature and chemical potential effects.

Findings

Shear viscosity to entropy density ratio ranges from 1.5 to 13 times the lower bound.

The ratio increases monotonically with chemical potential to temperature ratio.

Results depend on temperature between 185 and 300 MeV.

Abstract

We calculate the shear viscosity $\eta$ of a quark plasma through the two-flavor Nambu-Jona-Lasinio (NJL) model in the chiral limit, at finite temperature $T$, and baryon number chemical potential $\mu_B$. We solve the Boltzmann equation by using in the collision term cross sections that are correct to leading order in the coupling constant. We find the ratio of shear viscosity to entropy density above and slightly below the chiral transition temperature to vary from 1.5 to 13 times the conjectured lower bound of $(4\pi)^{-1}$ depending on the chemical potential to temperature ratio. Ratio of shear viscosity to entropy density is found to be a monotonically increasing function of the ratio of chemical potential to temperature for temperatures between 185 and 300 MeV.