A model realizing inverse seesaw and resonant leptogenesis

TL;DR

This paper presents a new inverse seesaw model with two types of singlet fermions that naturally explains the keV-scale Majorana mass and achieves successful resonant leptogenesis with reduced hierarchy among parameters.

Contribution

The model introduces a novel seesaw mechanism between singlet fermions, reducing parameter hierarchy and enabling resonant leptogenesis.

Findings

Reduces hierarchy among mass parameters by a factor of 10^4.

Achieves successful resonant leptogenesis with natural mass degeneracy.

Provides a natural explanation for keV-scale Majorana mass.

Abstract

We construct a model realizing the inverse seesaw mechanism. The model has two types of gauge singlet fermions in addition to right-handed neutrinos. A required Majorana mass scale (keV scale) for generating the light active neutrino mass in the conventional inverse seesaw can be naturally explained by a "seesaw" mechanism between the two singlet fermions in our model. We find that our model can decrease the magnitude of hierarchy among the mass parameters by $\mathcal{O}(10^4)$ from that in the conventional inverse seesaw model. We also show that a successful resonant leptogenesis occurs for generating the baryon asymmetry of the universe in our model. The desired mass degeneracy for the resonant leptogenesis can also be achieved by the "seesaw" between the two singlet fermions.