Equilibration rates in a strongly coupled nonconformal quark-gluon plasma

TL;DR

This paper investigates how strongly coupled quark-gluon plasmas without conformal symmetry equilibrate, finding that their thermalization time is primarily determined by temperature, regardless of additional scales.

Contribution

It introduces the first study of equilibration rates in nonconformal strongly coupled plasmas using holography, revealing temperature as the key factor in thermalization times.

Findings

Quasinormal mode frequencies scale with temperature.

Thermalization time is roughly proportional to inverse temperature.

Behavior is consistent across different holographic models.

Abstract

We initiate the study of equilibration rates of strongly coupled quark-gluon plasmas in the absence of conformal symmetry. We primarily consider a supersymmetric mass deformation within ${\cal N}=2^{*}$ gauge theory and use holography to compute quasinormal modes of a variety of scalar operators, as well as the energy-momentum tensor. In each case, the lowest quasinormal frequency, which provides an approximate upper bound on the thermalization time, is proportional to temperature, up to a pre-factor with only a mild temperature dependence. We find similar behaviour in other holographic plasmas, where the model contains an additional scale beyond the temperature. Hence, our study suggests that the thermalization time is generically set by the temperature, irrespective of any other scales, in strongly coupled gauge theories.