Leptogenesis with small violation of B-L

TL;DR

This paper demonstrates that successful leptogenesis can occur at lower heavy neutrino masses (~10^6 GeV) without resonance, aligning thermal leptogenesis with gravitino constraints in supersymmetry.

Contribution

It shows that leptogenesis is viable at lower neutrino masses without relying on resonant CP asymmetry enhancement, challenging previous assumptions.

Findings

Leptogenesis feasible at M1 ~ 10^6 GeV

No need for degenerate heavy neutrinos for CP asymmetry

Aligns thermal leptogenesis with gravitino bounds

Abstract

We analyze leptogenesis in the context of seesaw models with almost conserved lepton number, focusing on the L-conserving contribution to the flavoured CP asymmetries. We find that, contrary to previous claims, successful leptogenesis is feasible for masses of the lightest heavy neutrino as low as M1 ~ 10^6 GeV, without resorting to the resonant enhancement of the CP asymmetry for strongly degenerate heavy neutrinos. This lower limit renders thermal leptogenesis compatible with the gravitino bound in supersymmetric scenarios.