Thermalization and confinement in strongly coupled gauge theories

TL;DR

This paper uses holography to study how strongly coupled, confining gauge theories thermalize after perturbations, revealing timescales and universal behaviors relevant to real-world QCD-like theories.

Contribution

It provides a detailed analysis of thermalization processes in confining gauge theories via solving non-linear Einstein equations with time-dependent boundary conditions.

Findings

Thermalization timescales depend on the perturbation parameters.

A universal scaling regime appears in the abrupt quench limit.

Confinement scale influences the thermalization process.

Abstract

Quantum field theories of strongly interacting matter sometimes have a useful holographic description in terms of the variables of a gravitational theory in higher dimensions. This duality maps time dependent physics in the gauge theory to time dependent solutions of the Einstein equations in the gravity theory. In order to better understand the process by which "real world" theories such as QCD behave out of thermodynamic equilibrium, we study time dependent perturbations to states in a model of a confining, strongly coupled gauge theory via holography. Operationally, this involves solving a set of non-linear Einstein equations supplemented with specific time dependent boundary conditions. The resulting solutions allow one to comment on the timescale by which the perturbed states thermalize, as well as to quantify the properties of the final state as a function of the perturbation parameters. We comment on the influence of the dual gauge theory's confinement scale on these results, as well as the appearance of a previously anticipated universal scaling regime in the "abrupt quench" limit.