Hybrid Textures of the Right-Handed Majorana Neutrino Mass Matrix

TL;DR

This paper systematically studies specific hybrid textures of the right-handed Majorana neutrino mass matrix arising from the type-I seesaw mechanism, identifying viable configurations consistent with current experimental data.

Contribution

It introduces a new class of hybrid textures with one zero and one equality in the mass matrix, derived from discrete symmetries, and analyzes their phenomenological implications.

Findings

Six hybrid textures are compatible with experimental data.

Predictions for the effective Majorana mass of the electron neutrino.

Constraints on the Dirac CP-violating phase.

Abstract

We perform a systematic study of neutrino mass matrices having a vanishing cofactor and an equality between two cofactors of the mass matrix. Such texture structures of the effective neutrino mass matrix arise from type-I seesaw mechanism when the Dirac neutrino mass matrix is diagonal with equal elements and the right-handed Majorana neutrino mass matrix has hybrid textures with one equality of matrix elements and one zero matrix element. For three right-handed neutrinos there are sixty possible hybrid textures out of which only six are excluded by the present experimental data. We show that such textures can be derived using discrete symmetries. The predictions of experimentally allowed textures are examined for unknown parameters such as the effective Majorana mass of the electron neutrino and the Dirac-type CP-violating phase.