Establishing the Range of Applicability of Hydrodynamics in High-Energy Collisions

We simulate the space-time dynamics of high-energy collisions based on a microscopic kinetic description in the conformal relaxation time approximation, in order to determine the range of applicability of an effective description in relativistic viscous hydrodynamics. We find that hydrodynamics provides a quantitatively accurate description of collective flow when the average inverse Reynolds number Re-1 is sufficiently small and the early preequilibrium stage is properly accounted for. We further discuss the implications of our findings for the (in)applicability of hydrodynamics in proton-proton, proton-nucleus, and light nucleus collisions.

Automated summary

We simulate the space-time dynamics of high-energy collisions using a microscopic kinetic description and find that hydrodynamics provides an accurate description of collective flow in certain conditions. Our findings have implications for the applicability of hydrodynamics in different types of collisions.