Effect of Soft Modes on the Shear Viscosity of Quark Matter

TL;DR

This paper investigates how soft collective modes influence the shear viscosity of quark matter at finite temperature and density, revealing that these modes significantly reduce viscosity and affect fluid dynamics.

Contribution

It introduces a calculation of quark shear viscosity considering interactions with soft modes using the RPA, highlighting the impact on viscosity and fluid properties.

Findings

Shear viscosity decreases due to soft mode interactions.

Quark mean free path is short, indicating strong interactions.

Viscosity increases with temperature above 200 MeV.

Abstract

We calculate shear viscosity of the quark matter at finite temperature and density. If we assume that the quark interacts with the soft mode, which is a collective mode of quark-antiquark pair, the self energy of the quark is calculated by using the quasi-particle random phase approximation. It is shown that its imaginary part is large and the mean free path of the quark is short. With the use of the Kubo formula, the shear viscosity of quark matter becomes small. The Reynolds number of the quark matter is estimated to be about $3\sim 30$. As the temperature increases, the shear viscosity increases gradually for $T>200{\rm MeV}$. Moreover it is shown that the shear viscosity is not sensitive to the chemical potential.