Generating Tensor Polarization from Shear Stress

TL;DR

This paper derives a hydrodynamic expression linking tensor polarization of massive spin-1 particles to shear stress, providing a new way to calculate vector-meson spin alignment in heavy-ion collisions.

Contribution

It introduces a novel formula connecting tensor polarization to shear stress using quantum kinetic theory and a modified moments method.

Findings

Tensor polarization is determined by shear-stress tensor.

Provides a formula for numerical calculations of spin alignment.

Links polarization effects to hydrodynamic shear stress in relativistic fluids.

Abstract

We derive an expression for the tensor polarization of a system of massive spin-1 particles in a hydrodynamic framework. Starting from quantum kinetic theory based on the Wigner-function formalism, we employ a modified method of moments which also takes into account all spin degrees of freedom. It is shown that the tensor polarization of an uncharged fluid is determined by the shear-stress tensor. In order to quantify this novel polarization effect, we provide a formula which can be used for numerical calculations of vector-meson spin alignment in relativistic heavy-ion collisions.