Particle polarization, spin tensor and the Wigner distribution in relativistic systems

TL;DR

This paper explores the theoretical connection between particle spin polarization, the relativistic spin tensor, and the Wigner distribution, aiming to improve predictions for experimental heavy-ion collision data.

Contribution

It introduces a framework linking the relativistic spin tensor and Wigner function to particle polarization, enhancing the theoretical tools for analyzing spin phenomena in relativistic systems.

Findings

Established a connection between the relativistic spin tensor and particle polarization.

Linked the Wigner function to average particle polarization.

Provided insights useful for interpreting heavy-ion collision spin data.

Abstract

Particle spin polarization is known to be linked both to rotation (angular momentum) and magnetization of a many particle system. However, in the most common formulation of relativistic kinetic theory, the spin degrees of freedom appear only as degeneracy factors multiplying phase-space distributions. Thus, it is important to develop theoretical tools that allow to make predictions regarding the spin polarization of particles, which can be directly confronted with experimental data. Herein, we discuss a link between the relativistic spin tensor and particle spin polarization, and elucidate the connections between the Wigner function and average polarization. Our results may be useful for theoretical interpretation of heavy-ion data on spin polarization of the produced hadrons.