Transport properties of anisotropically expanding quark-gluon plasma within a quasi-particle model

TL;DR

This paper investigates the shear and bulk viscosities of quark-gluon plasma using a quasi-particle model based on lattice QCD, highlighting the dominance of matter sector contributions and the temperature dependence near the QCD transition.

Contribution

It introduces a semi-classical transport approach within a quasi-particle model to analyze the transport coefficients of quark-gluon plasma, emphasizing the matter sector's dominance and temperature effects.

Findings

Matter sector dominates shear and bulk viscosities.

Viscosities increase sharply near the QCD transition temperature.

Both viscosities are significant in heavy ion collision conditions.

Abstract

The bulk and shear viscosities ($\eta$ and $\zeta$) have been studied for quark-gluon-plasma produced in relativistic heavy ion collisions within semi-classical transport theory, in a recently proposed quasi-particle model of (2+1)-flavor lattice QCD equation of state. These transport parameters have been found to be highly sensitive to the interactions present in hot QCD. Contributions to the transport coefficients from both the gluonic sector and the matter sector have been investigated. The matter sector is found to be significantly dominating over the gluonic sector, in both the cases of $\eta$ and $\zeta$. The temperature dependences of the quantities, $\zeta/{\mathcal S}$, and $\zeta/\eta$ indicate a sharply rising trend for the $\zeta$, closer to the QCD transition temperature. Both $\eta$, and $\zeta$ are shown to be equally significant for the temperatures that are accessible in the relativistic heavy ion collision experiments, and hence play crucial role while investigating the properties of the quark-gluon plasma.