Matching of nonthermal initial conditions and hydrodynamic stage in ultrarelativistic heavy-ion collisions

TL;DR

This paper introduces a simple phenomenological approach to model the preequilibrium dynamics in ultrarelativistic heavy-ion collisions, enabling a smooth transition from nonthermal initial states to hydrodynamic evolution of the quark-gluon plasma.

Contribution

It presents a new method based on macroscopic relaxation equations to connect far-from-equilibrium initial conditions with hydrodynamics in heavy-ion collisions.

Findings

Allows calculation of preequilibrium dynamics from nonthermal initial states.

Provides a way to determine the energy-momentum tensor at hydrodynamic initialization.

Introduces two parameters to characterize the prehydrodynamic stage.

Abstract

A simple approach is proposed allowing actual calculations of the preequilibrium dynamics in ultrarelativistic heavy-ion collisions to be performed for a far-from-equilibrium initial state. The method is based on the phenomenological macroscopic equations that describe the relaxation dynamics of the energy-momentum tensor and are motivated by Boltzmann kinetics in the relaxation-time approximation. It gives the possibility to match smoothly a nonthermal initial state to the hydrodynamics of the quark gluon plasma. The model contains two parameters, the duration of the prehydrodynamic stage and the initial value of the relaxation-time parameter, and allows one to assess the energy-momentum tensor at a supposed time of initialization of the hydrodynamics.