Wash-out inN₂-dominated leptogenesis

Abstract

We study the wash-out of a cosmological baryon asymmetry produced via leptogenesis by subsequent interactions. Therefore we focus on a scenario in which a lepton asymmetry is established in the out-of-equilibrium decays of the next-to-lightest right-handed neutrino. We apply the full classical Boltzmann equations without the assumption of kinetic equilibrium and including all quantum statistical factors to calculate the wash-out of the lepton asymmetry by interactions of the lightest right-handed state. We include scattering processes with top quarks in our analysis. This is of particular interest since the wash-out is enhanced by scatterings and the use of mode equations with quantum statistical distribution functions. In this way we provide a restriction on the parameter space for this scenario.

Decay of a Yukawa fermion at finite temperature and applications to leptogenesis

“…As for all effects arising from thermal field theory, the effects are only important in the weak washout regime, where leptogenesis takes place at high temperatures. We are aware of the progress that is currently being made in approaching the effects of quantum statistics [30][31][32][33], quantum transport equations [34][35][36][37][38][39] or other collective phenomena as e.g. the Landau-Pomeranchuk effect [8].…”