Quark Polarization in a Viscous Quark-Gluon Plasma

TL;DR

This paper investigates how quark spin polarization develops and is affected by viscosity and initial flow shear in a viscous quark-gluon plasma created in non-central heavy-ion collisions.

Contribution

It introduces a model for the evolution of quark polarization considering viscous effects and initial flow shear in a quark-gluon plasma.

Findings

Final polarization depends on viscosity and initial shear.

Viscous effects significantly influence quark polarization evolution.

Initial flow shear impacts the magnitude of polarization.

Abstract

Quarks produced in the early stage of non-central heavy-ion collisions could develop a global spin polarization along the opposite direction of the reaction plane due to the spin-orbital coupling via parton interaction in a medium that has finite longitudinal flow shear along the direction of the impact parameter. We study how such polarization evolves via multiple scattering in a viscous quark-gluon plasma with an initial laminar flow. The final polarization is found to be sensitive to the viscosity and the initial shear of local longitudinal flow.