Expansion attractor in classical Yang-Mills theory

Abstract

Applications of the concept of a hydrodynamic attractor have been mostly constrained to the context of hydrodynamization in heavy ion collisions. Deepening the understanding of the general phenomenon requires generalizing it to other contexts in order to see which facettes are truly universal and not a peculiarity of equilibrating conformal Bjorken flow. As part of this endeavor, this work aims to study the behaviour in a system that does not hydrodynamize, but nevertheless loses memory through expansion. We find that the system goes through three stages. At early times, expansion drives the ratio $P_L/ϵ$ to converge to $-1$ as ${\tau }^{-2}$. This memory loss is partially restored at intermediate times, when interaction dominated degrees of freedom through expansion dominated evolution grow quadraticallly in time. At late times, interactions shuffle of information in state space without significant memory loss or restoration.

Comments: 10+2 pages, 7 figures, 2 tables