QCD Matter Thermalization at RHIC and LHC

TL;DR

This paper investigates how quark-gluon plasma created in heavy ion collisions at RHIC and LHC reaches thermal and chemical equilibrium using a perturbative QCD-based parton cascade, comparing different initial conditions.

Contribution

It demonstrates that kinetic equilibration is robust against initial conditions, while chemical equilibration is sensitive, providing estimates for thermalization times and final parton energies.

Findings

Thermalization time is between 1 and 1.5 fm/c.

Kinetic equilibration is nearly independent of initial conditions.

Final parton transverse energy matches RHIC data and estimates for LHC.

Abstract

Employing the perturbative QCD inspired parton cascade, we investigate kinetic and chemical equilibration of the partonic matter created in central heavy ion collisions at RHIC and LHC energies. Two types of initial conditions are chosen. One is generated by the model of wounded nucleons using the PYTHIA event generator and Glauber geometry. Another is considered as a color glass condensate. We show that kinetic equilibration is almost independent on the chosen initial conditions, whereas there is a sensitive dependence for chemical equilibration. The time scale of thermalization lies between 1 and 1.5 fm/c. The final parton transverse energy obtained from BAMPS calculations is compared with the RHIC data and is estimated for the LHC energy.