Form Invariance and Symmetry in the Neutrino Mass Matrix

TL;DR

This paper explores the symmetries of the neutrino mass matrix, presents models with specific Higgs content to explain lepton masses, and discusses implications for leptogenesis and baryon asymmetry.

Contribution

It introduces new symmetry considerations for the neutrino mass matrix and proposes models with extended Higgs sectors to explain lepton mass hierarchies and baryogenesis.

Findings

Invariant unitary matrices for neutrino mass textures

A model with three light Higgs doublets and one heavy triplet

Potential for generating baryon asymmetry via leptogenesis

Abstract

We present the general form of the unitary matrices keeping invariant the Majorana neutrino mass matrix of specific texture suitable for explaining oscillation data. In the case of the Tri-bimaximal pattern with two degenerate masses we give a specific realization of the underlying $U(1)$ symmetry which can be uplifted to a symmetry in a complete theory including charged leptons. For this, we present a model with three light SM-like Higgs doublets and one heavy Higgs triplet and find that one can accommodate the hierarchy of the charged lepton masses. The lepton mass spectrum can also be achieved in another model extending the SM with three SM-singlet scalars transforming non trivially under the flavor symmetry. We discuss how such a model has room for generating enough baryon asymmetry through leptogenesis in the framework of Type-I and II seesaw mechanisms.