Kinetic theory and evolution of cosmological fluctuations with neutrino number asymmetry

TL;DR

This paper derives a kinetic equation for chiral matter with non-zero chemical potential, analyzing how neutrino asymmetry influences cosmological perturbations and gravitational waves in the early universe.

Contribution

It introduces a new kinetic framework for chiral matter at non-zero chemical potential, linking neutrino asymmetry to cosmological fluctuation evolution.

Findings

Derived a kinetic equation for chiral matter with chemical potential.

Provided equations for gravity waves influenced by lepton asymmetry.

Facilitates assessment of neutrino chemical potential effects on cosmology.

Abstract

We derive a kinetic equation for chiral matter at non-zero chemical potential that governs the response of the parity odd part of the distribution function to perturbations of the Robertson-Walker metric. The derivation is based on a recent evaluation of the gravitational polarization tensor at non-zero chemical potential. We also provide the equations for gravity waves that follow from the anisotropic stress tensor describing the lepton asymmetry. These equations can be used to assess the effects that a non-zero neutrino chemical potential would have on the evolution of cosmological perturbations.