Transport coefficients of the Gribov-Zwanziger plasma

TL;DR

This paper investigates the transport properties of a gluon plasma modeled with Gribov-Zwanziger quantization, revealing strong conformal symmetry breaking and explicit expressions for viscosities.

Contribution

It provides the first explicit derivation of shear and bulk viscosities for a Gribov-Zwanziger plasma, incorporating confinement effects into transport coefficient calculations.

Findings

Viscosities are explicitly derived and numerically validated.

The ratio ζ/η scales as 1/3 - c_s^2, indicating strong conformal symmetry breaking.

The plasma exhibits non-conformal behavior even at high temperatures.

Abstract

We study dynamic features of a plasma consisting of gluons whose infrared dynamics is improved by the Gribov-Zwanziger quantization. This approach embodies essential features of color confinement which set the plasma apart from conventional quasiparticle systems in several aspects. Our study focusses on a boost-invariant expansion for in- and out-of-equilibrium settings, which at late times can be characterized by the sound velocity, $c_s$, and the shear, $\eta$, and bulk, $\zeta$, viscosities. We obtain explicit expressions for the transport coefficients $\eta$ and $\zeta$ and check that they are consistent with the numerical solutions of the kinetic equation. At high temperature, keeping both the Gribov parameter and the relaxation time constant, we find a scaling $\zeta/\eta \propto 1/3 - c_s^2$ which manifests strong breaking of conformal symmetry in contrast to the case of weakly coupled plasmas.