Leptogenesis with Heavy Majorana Neutrinos Reexamined

TL;DR

This paper reexamines leptogenesis involving heavy Majorana neutrinos, comparing different calculation methods for lepton asymmetry and recalculating the asymmetry in the small mass difference limit.

Contribution

It provides a comparative analysis of approaches to calculate lepton asymmetry and offers a recalculation in the small mass difference regime.

Findings

Different approaches yield consistent results for lepton asymmetry.

Recalculation confirms the behavior of asymmetry in the small mass difference limit.

Clarifies the role of CP violation in heavy Majorana neutrino decays.

Abstract

The mass term for Majorana neutrinos explicitly violates lepton number. Several authors have used this fact to create a lepton asymmetry in the universe by considering CP violating effects in the one loop self-energy correction for the decaying heavy Majorana neutrino. We compare and comment on the different approaches used to calculate the lepton asymmetry including those using an effective Hamiltonian and resummed propagators. We also recalculate the asymmetry in the small mass difference limit.