Presented by Shu Lin, Stony Brook University
I will start with a short review on various probes to Quark Gluon Plasma studied by AdS/CFT. The study of the probe typically amounts to solving linearized Einstein equation. The more challenging task is to understand the equilibration of matter and formation of QGP. I will talk about a specific gravitational collapse model, which is dual to the thermalization of gauge field on the boundary. We found the spectral density of stress energy tensor differs from its thermal counterpart by some general oscillation. I will also talk about the recent works on entropy estimation in heavy ion collision from gravitational shock wave collision. We found the existence of critical impact parameter, beyond which no horizon can form. In the dual field theory, it means matter produced in the collision cannot thermalize.