On holographic thermalization and gravitational collapse of tachyonic scalar fields

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 Δt a≳ t a≳ - Δt. 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 Δ 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 Δ t ≳1T 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 [10, 11]. © 2013 SISSA.