Nonequilibrium quark production in the expanding QCD plasma

TL;DR

This paper reports on real-time lattice simulations of nonequilibrium quark production in an expanding QCD plasma, showing linear growth in quark density and early-time scaling laws, consistent with kinetic theory estimates.

Contribution

It provides the first detailed lattice simulation results for quark production in an expanding QCD plasma, highlighting the dynamics and scaling behaviors.

Findings

Quark number density grows linearly over time.

Early-time quark distributions follow a nonequilibrium scaling law.

Growth rate aligns with kinetic theory estimates for two-to-two scatterings.

Abstract

We present real-time lattice simulation results for nonequilibrium quark production from an over-occupied gluon plasma in longitudinally expanding geometry. The quark number density per unit transverse area and rapidity shows almost linear growth in time, and its growth rate appears to be consistent with a simple kinetic theory estimate involving only two-to-two scattering processes in small-angle approximation. We also find that quarks produced at early times satisfy a nonequilibrium scaling law.