Leptogenesis: beyond the minimal type I seesaw scenario

TL;DR

This paper reviews various seesaw models beyond the minimal type I scenario that can successfully implement leptogenesis, explaining the origin of the universe's matter-antimatter asymmetry.

Contribution

It provides a comprehensive analysis of alternative seesaw mechanisms like type-II, type-III, and mixed models for leptogenesis, expanding beyond the standard type I framework.

Findings

Multiple seesaw scenarios can realize leptogenesis successfully.

Type-II and type-III models offer viable alternatives to type I.

Mixed frameworks provide additional pathways for baryogenesis.

Abstract

Numerous recent evidences for neutrino masses have established the leptogenesis mechanism as a very natural possible explanation for the baryon asymmetry of the Universe. The explicit realization of this mechanism depends on the neutrino mass model considered. If the right-handed type-I seesaw model of neutrino masses is certainly the most straightforward, it is not the only natural one, especially in the framework of explicit GUT realizations of the seesaw. In this review we discuss in detail the various seesaw scenarios that can implement the leptogenesis mechanism successfully, beyond the paradigm of the pure standard type-I seesaw model. This includes scenarios based on the existence of scalar triplets (type-II), of fermion triplets (type-III) as well as mixed seesaw frameworks.