Equilibration of a strongly interacting plasma: holographic analysis of local and nonlocal probes

Loredana Bellantuono,G.E Bruno,C Corianò,P Colangelo,S Spagnolo,D.M Creanza,F De Fazio,E Nappi,G Chiodini

doi:10.1051/epjconf/201612900041

Abstract

The relaxation of a strongly coupled plasma towards the hydrodynamic regime is studied by analyzing the evolution of local and nonlocal observables in the holographic approach. The system is driven in an initial anisotropic and far-from equilibrium state through an impulsive time-dependent deformation (quench) of the boundary spacetime geometry. Effective temperature and entropy density are related to the position and area of a black hole horizon, which has formed as a consequence of the distortion. The behavior of stress-energy tensor, equal-time correlation functions and Wilson loops of different shapes is examined, and a hierarchy among their thermalization times emerges: probes involving shorter length scales thermalize faster.

Highlights

The relaxation of a strongly coupled plasma towards the hydrodynamic regime is studied by analyzing the evolution of local and nonlocal observables in the holographic approach
The deconfined and strongly-coupled plasma produced in relativistic heavy ion collisions experiments is characterized by an initial configuration which is dense, hot and highly anisotropic
In order to mimic the effects of heavy ion collisions and reproduce the initial far-from-equilibrium state, a time-dependent deformation is introduced to the metric on the boundary geometry [2]

Summary

Boundary sourcing

The deconfined and strongly-coupled plasma produced in relativistic heavy ion collisions experiments is characterized by an initial configuration which is dense, hot and highly anisotropic. In order to mimic the effects of heavy ion collisions and reproduce the initial far-from-equilibrium state, a time-dependent deformation (quench) is introduced to the metric on the boundary geometry (boundary sourcing) [2]. The metric functions A, B and Σ depend only on r and τ because of the imposed symmetries They are solutions of Einstein’s equations with negative cosmological constant, that can be rephrased as [2]: Σ(Σ ) + 2Σ Σ − 2Σ2 = 0.

Viscous hydrodynamic regime

Thermalization probes

Findings

Hierarchy among thermalization times