Inhomogeneous Thermalization in Strongly Coupled Field Theories

TL;DR

This paper investigates the early-time evolution of inhomogeneous strongly coupled field theories using AdS/CFT, finding that free streaming describes the initial dynamics and transitions smoothly into hydrodynamics.

Contribution

It introduces an analytic approach to model non-hydrodynamic early time evolution with inhomogeneities in strongly coupled systems via AdS/CFT correspondence.

Findings

Early-time evolution matches free streaming behavior.

Stress tensor transitions to second order hydrodynamics.

Analytic techniques applicable to other far-from-equilibrium systems.

Abstract

To describe theoretically the creation and evolution of the quark-gluon plasma, one typically employs three ingredients: a model for the initial state, non-hydrodynamic early time evolution, and hydrodynamics. In this paper we study the non-hydrodynamic early time evolution using the AdS/CFT correspondence in the presence of inhomogeneities. We find that the AdS description of the early time evolution is well-matched by free streaming. Near the end of the early time interval where our analytic computations are reliable, the stress tensor agrees with the second order hydrodynamic stress tensor computed from the local energy density and fluid velocity. Our techniques may also be useful for the study of far-from-equilibrium strongly coupled systems in other areas of physics.