Kinetic equations for sterile neutrinos from thermal fluctuations

TL;DR

This paper derives non-linear kinetic equations for sterile neutrinos and lepton asymmetries using thermal fluctuation correlations, applicable to various sterile neutrino models and relevant for leptogenesis and dark matter.

Contribution

It introduces a general framework for kinetic equations of sterile neutrinos based on thermal fluctuation correlations, valid for any number and mass spectrum.

Findings

Derived kinetic equations from thermal fluctuations

Applicable to low-scale leptogenesis and dark matter production

Framework valid for arbitrary sterile neutrino parameters

Abstract

We obtain non-linear kinetic equations for sterile neutrino occupancies and lepton minus baryon numbers by matching real time correlation functions of thermal fluctuations computed in an effective description to those computed in thermal quantum field theory. After expanding in the sterile-neutrino Yukawa couplings, the coefficients in the equations are written as real time correlation functions of Standard Model operators. Our kinetic equations are valid for an arbitrary number of sterile neutrinos of any mass spectrum. They can be used to describe, e.g., low-scale leptogenesis via neutrino oscillations, or sterile neutrino dark matter production in the Higgs phase.