Leptogenesis in natural low-scale seesaw mechanisms

TL;DR

This paper investigates how approximate lepton number conservation can enable successful leptogenesis at low scales within seesaw models, linking neutrino mass smallness and heavy state degeneracy, and explores experimental testability.

Contribution

It introduces a minimal Standard Model extension with approximate lepton number symmetry to realize low-scale leptogenesis, providing analytical and numerical viability analysis.

Findings

Viable solutions for low-scale leptogenesis identified

Degeneracy in heavy sterile neutrino masses crucial for success

Potential for experimental testing of the scenario

Abstract

We explore the hypothesis of having an approximate lepton number conservation as a way to achieve a successful leptogenesis in low-scale seesaw mechanisms. The smallness of the active neutrino masses, as well as a strong degeneracy in the mass spectrum of the heavy sterile states, are both consequence of the assumed approximate symmetry. We propose a minimal extension of the Standard Model in order to implement the idea, and perform an analytical and numerical study to determine the viable solutions in the model and the testability of this leptogenesis scenario in future experiments.