Shear Viscosity in a Perturbative Quark-Gluon-Plasma

TL;DR

This paper calculates the shear viscosity to entropy density ratio of a perturbative quark-gluon plasma using a microscopic transport model and the Kubo formalism, revealing invariance to chemical composition when expressed as a function of energy density.

Contribution

It introduces a method to compute shear viscosity in a perturbative QGP and finds invariance of /s with respect to chemical composition when using energy density as a variable.

Findings

/s ratio becomes invariant to chemical composition when plotted against energy density.

The transport model based on Boltzmann equation effectively simulates a thermalized QGP.

Shear viscosity is computed as a function of temperature and system composition.

Abstract

Among the key features of hot and dense QCD matter produced in ultra-relativistic heavy-ion collisions at RHIC is its very low shear viscosity, indicative of the properties of a near-ideal fluid, and a large opacity demonstrated by jet energy loss measurements. In this work, we utilize a microscopic transport model based on the Boltzmann equation with quark and gluon degrees of freedom and cross sections calculated from perturbative Quantum Chromodynamics to simulate an ideal Quark-Gluon-Plasma in full thermal and chemical equilibrium. We then use the Kubo formalism to calculate the shear viscosity to entropy density ratio of the medium as a function of temperature and system composition. One of our key results is that the shear viscosity over entropy-density ratio $\eta/s$ becomes invariant to the chemical composition of the system when plotted as a function of energy-density instead of temperature.