Longitudinal Coherence in a Holographic Model of p-Pb Collisions

Understand

As a model of the longitudinal structure in heavy ion collisions, we simulate gravitational shock wave collisions in anti-de Sitter space in which each shock is composed of multiple constituents.

• We find that all constituents act coherently, and their separation leaves no imprint on the resulting plasma, when this separation is $\lesssim 0.26 / T_{hyd}$, with $T_{hyd}$ the temperature of the plasma at the time when hydrodynamics first becomes applicable.
• In particular, the center-of-mass of the plasma coincides with the center-of-mass of all the constituents participating in the collision, as opposed to the center-of-mass of the individual collisions.
• We discuss the implications for nucleus-nucleus and proton-nucleus collisions.