Helical massive fermions under rotation

TL;DR

This paper investigates the behavior of massive fermions under rotation at finite temperature and chemical potential, introducing a helicity chemical potential to analyze conserved currents and quantum corrections, with implications for heavy ion collisions.

Contribution

It introduces a helicity chemical potential framework for massive fermions under rotation, deriving analytic transport equations and quantum corrections relevant for finite mass effects.

Findings

Helicity charge current remains conserved at finite mass.

Analytic constitutive equations for non-equilibrium transport are derived.

Mass effects are significant for axial charge conductivity, especially in heavy ion contexts.

Abstract

The properties of a massive fermion field undergoing rigid rotation at finite temperature and chemical potential are discussed. The polarisation imbalance is taken into account by considering a helicity chemical potential, which is dual to the helicity charge operator. The advantage of the proposed approach is that, as opposed to the axial current, the helicity charge current remains conserved at finite mass. A computation of thermal expectation values of the vector, helicity and axial charge currents, as well as of the fermion condensate and stress-energy tensor is provided. In all cases, analytic constitutive equations are derived for the non-equilibrium transport terms, as well as for the quantum corrections to the equilibrium terms (which are derived using an effective relativistic kinetic theory model for fermions with helicity imbalance) in the limit of small masses. In the context of the parameters which are relevant to relativistic heavy ion collisions, the expressions derived in the massless limit are shown to remain valid for masses up to the thermal energy, except for the axial charge conductivity in the azimuthal direction, which presents strong variations with the particle mass.