Initial conditions for hydrodynamics from weakly coupled pre-equilibrium evolution

TL;DR

This paper develops a method using effective kinetic theory to accurately model the pre-equilibrium phase in heavy-ion collisions, connecting initial conditions to hydrodynamics with a Green function approach.

Contribution

It introduces a Green function that propagates initial perturbations through pre-equilibrium evolution, enabling a perturbatively controlled transition to hydrodynamics.

Findings

Provides a Green function for pre-equilibrium evolution

Enables modeling from saturated nuclei to hydrodynamics

Offers a perturbatively controlled approach

Abstract

We use effective kinetic theory, accurate at weak coupling, to simulate the pre-equilibrium evolution of transverse energy and flow perturbations in heavy-ion collisions. We provide a Green function which propagates the initial perturbations to the energy-momentum tensor at a time when hydrodynamics becomes applicable. With this map, the complete pre-thermal evolution from saturated nuclei to hydrodynamics can be modelled in a perturbatively controlled way.