Dissipative Spin Dynamics in Relativistic Matter

TL;DR

This paper develops a classical kinetic theory framework for spin-1/2 particles in relativistic fluids, incorporating dissipation to understand viscous and diffusive effects in spin dynamics.

Contribution

It extends perfect-fluid spin hydrodynamics to include dissipation by deriving kinetic coefficients from classical kinetic equations with relaxation time approximation.

Findings

Derived new kinetic coefficients for dissipative spin effects.

Established a kinetic-theory-based structure for viscous and diffusive terms.

Extended hydrodynamic models to account for dissipation in spin-polarized fluids.

Abstract

Using classical description of spin degrees of freedom, we extend recent formulation of the perfect-fluid hydrodynamics for spin-polarized fluids to the case including dissipation. Our work is based on the analysis of classical kinetic equations for massive particles with spin-1/2, with the collision terms treated in the relaxation time approximation. The kinetic-theory framework determines the structure of viscous and diffusive terms and allows to explicitly calculate a complete set of new kinetic coefficients that characterize dissipative spin dynamics.