Quasi-Degenerate Neutrino Masses with Normal and Inverted Hierarchy

TL;DR

This paper investigates the effects of CP-phases on quasi-degenerate Majorana neutrino masses within μ-τ symmetry, analyzing predictions for mixing angles, neutrinoless double beta decay, and cosmological bounds for both mass hierarchies.

Contribution

It introduces a parameterization of neutrino mass matrices with two parameters under μ-τ symmetry, providing new insights into neutrino mass models and their observational implications.

Findings

Validates quasi-degenerate neutrino mass models for both hierarchies

Predicts solar mixing angle below tri-bimaximal value

Provides bounds on absolute neutrino mass from 0νββ decay and cosmology

Abstract

The effects of CP-phases on the three absolute quasi-degenerate Majorana neutrino (QDN) masses are stud-ied with neutrino mass matrices obeying {\mu} - {\tau} symmetry for normal as well as inverted hierarchical mass patterns. We have made further investigations on 1) the prediction of solar mixing angle which lies below tri-bimaximal mixing value in consistent with neutrino oscillation observational data, 2) the prediction on absolute neutrino mass parameter (mee) in 0{\nu}{\beta}{\beta} decay, and 3) cosmological bound on the sum of the three absolute neutrino masses. The numerical analysis is carried out through the parameterization of neu- trino mass matrices using only two unknown parameters ({\epsilon}, {\eta}) within {\mu} - {\tau} symmetry. The results show the validity of QDN mass models in both normal and inverted hierarchical patterns. These models are far from discrimination and hence not yet ruled out. The results presented in this article are new and have subtle ef- fects in the discrimination of neutrino mass models.