Calculation of bulk viscosity of QCD at zero temperature and finite chemical potential

TL;DR

This paper derives a formula for calculating QCD bulk viscosity at zero temperature and finite chemical potential, using Dyson-Schwinger equations, revealing no sharp peak behavior unlike at finite temperature.

Contribution

It introduces a direct formula linking bulk viscosity to the dressed quark propagator at finite chemical potential, based on Kubo's formula and low energy theorems.

Findings

Bulk viscosity at finite chemical potential is determined by the dressed quark propagator.

No sharp peak in bulk viscosity is observed at finite chemical potential.

The behavior differs from that at finite temperature.

Abstract

In this letter, based on Kubo's formula and the QCD low energy theorem, we propose a direct formula for calculating the bulk viscosity of QCD at finite chemical potential $\mu$ and zero temperature. According to this formula, the bulk viscosity at finite $\mu$ is totally determined by the dressed quark propagator at finite $\mu$. We then use a dynamical, confining Dyson-Schwinger equation model of QCD to calculate the bulk viscosity at finite $\mu$. It is found that no sharp peak behavior of the bulk viscosity at finite $\mu$ is observed, which is quite different from that of the bulk viscosity at finite temperature.