Collinear parton splitting in early thermalization and chemical equilibration

TL;DR

This paper presents a phenomenological model of early thermalization and chemical equilibration in high-energy heavy ion collisions, emphasizing collinear splitting and recombination of quarks and gluons, showing rapid thermalization but slower chemical equilibration.

Contribution

It introduces a new model based on collinear splitting and recombination to describe the early thermalization and chemical equilibration process.

Findings

Thermalization occurs rapidly within a short time.

Chemical equilibration proceeds more slowly than thermalization.

The model aligns with predictions of the glasma framework.

Abstract

Early local equilibration of a hot medium created in high-energy heavy ion collisions has been one of the long standing issues in hadron physics. The glasma model predicts that the medium initially has a large amount of high-momentum gluons but few quarks. We develop a phenomenological model based on collinear splitting and recombination of quarks and gluons for a simplified description of thermalization and chemical equilibration. We find that both could be achieved in a short time but chemical equilibration is slower than thermalization.