Leptogenesis with Linear, Inverse or Double Seesaw

TL;DR

This paper explores how different seesaw mechanisms within a left-right symmetric model can generate small neutrino masses and enable leptogenesis through decays of quasi-degenerate Majorana fermions or right-handed neutrinos.

Contribution

It demonstrates the realization of leptogenesis via resonant and non-resonant decays in a unified framework accommodating linear, inverse, and double seesaw mechanisms.

Findings

Resonant leptogenesis via quasi-degenerate Majorana fermions is feasible.

Seesaw suppressed Majorana masses for right-handed neutrinos enable leptogenesis.

The model unifies multiple seesaw mechanisms within a left-right symmetric framework.

Abstract

The left-right symmetric model with doublet and bi-doublet Higgs scalars can accommodate linear, inverse or double seesaw for generating small neutrino masses in the presence of three singlet fermions. If the singlet fermions have small Majorana masses, they can form three pairs of quasi-degenerate Majorana fermions with three right-handed neutrinos. The decays of the quasi-degenerate Majorana fermions can realize the resonant leptogenesis. Alternatively, the right-handed neutrinos can obtain seesaw suppressed Majorana masses if the singlet fermions are very heavy. In this case leptogenesis, with or without resonant effect, is allowed in the decays of the right-handed neutrinos.