Holographic thermalization in a top-down confining model

TL;DR

This paper investigates how a confinement scale influences the thermalization process in strongly coupled gauge theories with gravity duals, using the AdS soliton model and numerical simulations to identify different dynamical regimes.

Contribution

It provides the first detailed numerical analysis of holographic thermalization in a confining background, revealing regimes of black brane formation and persistent scalar shell scattering.

Findings

Black brane formation after energy injection depends on initial conditions.

Scalar shell scattering leads to persistent oscillations and modulation.

Analytical explanation links modulation to near-resonance between modes.

Abstract

It is interesting to ask how a confinement scale affects the thermalization of strongly coupled gauge theories with gravity duals. We study this question for the AdS soliton model, which underlies top-down holographic models for Yang-Mills theory and QCD. Injecting energy via a homogeneous massless scalar source that is briefly turned on, our fully backreacted numerical analysis finds two regimes. Either a black brane forms, possibly after one or more bounces, after which the pressure components relax according to the lowest quasinormal mode. Or the scalar shell keeps scattering, in which case the pressure components oscillate and undergo modulation on time scales independent of the (small) shell amplitude. We show analytically that the scattering shell cannot relax to a homogeneous equilibrium state, and explain the modulation as due to a near-resonance between a normal mode frequency of the metric and the frequency with which the scalar shell oscillates.