Hybrid textures in minimal seesaw mass matrices

TL;DR

This paper investigates hybrid textures in minimal seesaw neutrino mass matrices, identifying only six patterns compatible with current data that use minimal parameters, and explores their implications for experiments and leptogenesis.

Contribution

It classifies and analyzes six minimal-parameter neutrino mass matrix textures with hybrid properties, compatible with experimental data, advancing understanding of neutrino mass models.

Findings

Six viable mass matrix patterns identified

All mixing angles expressed with only two parameters

Implications for future experiments and leptogenesis discussed

Abstract

In the context of minimal seesaw framework, we study the implications of Dirac and Majorana mass matrices in which two rigid properties coexist, namely, equalities among mass matrix elements and texture zeros. In the first part of the study, we discuss general possibilities of the Dirac and Majorana mass matrices for neutrinos with such hybrid structures. We then classify the mass matrices into realistic textures which are compatible with global neutrino oscillation data and unrealistic ones which do not comply with the data. Among the large number of general possibilities, we find that only 6 patterns are consistent with the observations at the level of the most minimal number of free parameters. These solutions have only 2 adjustable parameters, so that all the mixing angles can be described in terms of the two mass differences or pure numbers. We analyze these textures in detail and discuss their impacts for future neutrino experiments and for leptogenesis.