Grazing Collisions of Gravitational Shock Waves and Entropy Production in Heavy Ion Collision

TL;DR

This paper investigates the formation of trapped surfaces in gravitational shock wave collisions using AdS/CFT correspondence to estimate black hole properties, with implications for understanding initial conditions in heavy ion collisions.

Contribution

It extends previous work by numerically analyzing trapped surfaces in non-central shock wave collisions and identifies a critical impact parameter relevant to heavy ion collision experiments.

Findings

Existence of a critical impact parameter for trapped surface formation.

Numerical trapped surface solutions for non-central shock wave collisions.

A simple solvable model of wall-on-wall shock wave collision.

Abstract

AdS/CFT correspondence is now widely used for study of strongly coupled plasmas, such as produced in ultrarelativistic heavy ion collisions at RHIC. While properties of equilibrated plasma and small deviations from equilibrium are by now reasonably well understood, its initial formation and thermal equilibration is much more challenging issue which remains to be studied. In the dual gravity language, these problems are related to formation of bulk black holes, and trapped surfaces we study in this work is a way to estimate the properties (temperature and entropy) of such black hole. Extending the work by Gubser et al, we find numerically trapped surfaces for non-central collision of shock waves with different energies. We observe a critical impact parameter, beyond which the trapped surface does not exist: and we argue that there are experimental indications for similar critical impact parameter in real collisions. We also present a simple solvable example of shock wave collision: wall-on-wall collision. The applicability of this approach to heavy ion collision is critically discussed.