Relaxation time for quark spin and thermal vorticity alignment in heavy-ion collisions

TL;DR

This paper calculates the relaxation time for quark and antiquark spin alignment with thermal vorticity in a quark-gluon plasma, revealing dependence on the plasma's angular velocity and implications for hadron polarization.

Contribution

It introduces a phenomenological model for quark spin-vorticity interaction and analyzes how the plasma's angular velocity affects spin alignment times.

Findings

Long relaxation times at small angular velocities

Efficient alignment at large angular velocities

Antiquarks have longer relaxation times than quarks

Abstract

We compute the relaxation time for quark/antiquark spin and thermal vorticity alignment in a quark-gluon plasma at finite temperature and quark chemical potential. We model the interaction of quark/antiquark spin with thermal vorticity as driven by a phenomenological modification of the elementary quark interaction with gluons. We find that in a scenario where the angular velocity of the quark-gluon plasma produced in a peripheral heavy-ion collision is small, quarks/antiquarks take a long time to align their spin with the vorticity. However, when the angular velocity created in the reaction is large, the alignment is efficient and well within the lifetime of the system created in the reaction. The relaxation time is larger for antiquarks which points out to a difference for the polarization of hadrons and antihadrons when this alignment is preserved during hadronization.