Non-conformal shock wave collisions
Understanding the out of equilibrium formation of a strongly coupled Quark-Gluon-Plasma is an important theoretical challenge, in particular in light of the upcoming massive experimental effort by both the LHC and RHIC on studying the extreme states of matter formed by ultra-relativistic heavy-ion collisions. In this talk I will use the gauge/gravity duality to model the first stage of a heavy ion collision by a collision of gravitational shockwaves in numerical relativity. This investigation of collisions of sheets of energy density in a non-conformal theory with a gravity dual is the first non-conformal holographic simulation of a heavy ion collision. I will discuss the new physics that arises (as compared to the much simpler conformal case) such as a new plasma relaxation channel, the equilibration of the conformal symmetry breaking scalar condensate and the presence of a sizeable bulk viscosity. These ingredients are crucial to make qualitative contact of the fast hydrodynamization process of hot plasmas with real-world QCD deconfinement matter above the critical point.