On holographic thermalization and gravitational collapse of tachyonic scalar fields

TL;DR

This paper investigates the thermalization process in a strongly coupled CFT via holography, modeling it as gravitational collapse of a tachyonic scalar field in AdS_5, revealing universal thermalization times and differences from global AdS collapse.

Contribution

It provides a detailed analysis of holographic thermalization with tachyonic scalar fields, including collapse dynamics and conserved currents, extending previous studies to new initial conditions and regimes.

Findings

Thermalization time t_T ~ O(1)/T across different perturbation durations.

Double-collapse solutions occur for perturbations with Delta t >= 1/T.

A conserved energy-momentum current elucidates collapse differences in Poincare vs global AdS.

Abstract

In this paper we study the thermalization of a spatially homogeneous system in a strongly coupled CFT. The non-equilibrium initial state is created by switching on a relevant perturbation in the CFT vacuum during Delta t >= t >= -Delta t. Via AdS/CFT, the thermalization process corresponds to the gravitational collapse of a tachyonic scalar field (m^2 = -3) in the Poincare patch of AdS_5. In the limit Delta t < 0.02/T, the thermalization time t_T is found to be quantitatively the same as that of a non-equilibrium state created by a marginal perturbation discussed in Ref. [5]. In the case Delta t >= 1/T, we also obtain double-collapse solutions but with a non-equilibrium intermediate state at t = 0. In all the cases our results show that the system thermalizes in a typical time t_T ~ O(1)/T. Besides, a conserved energy-moment current in the bulk is found, which helps understand the qualitative difference of the collapse process in the Poincare patch from that in global AdS[9, 10].