Admixture of quasi-Dirac and Majorana neutrinos with tri-bimaximal mixing

TL;DR

This paper presents a model combining quasi-Dirac and Majorana neutrinos with tri-bimaximal mixing, predicting an enhanced lower bound on neutrinoless double beta decay for inverse hierarchy, relevant for upcoming experiments.

Contribution

It introduces a bimodal neutrino model using S4 symmetry with specific mixing and mass assumptions, extending previous frameworks.

Findings

Lower bound on m_ee is doubled for inverse hierarchy.

Model predicts observable neutrinoless double beta decay signals.

Utilizes S4 symmetry to achieve tri-bimaximal mixing.

Abstract

We propose a realization of the so-called bimodal/schizophrenic model proposed recently. We assume S4, the permutation group of four objects as flavor symmetry giving tri-bimaximal lepton mixing at leading order. In these models the second massive neutrino state is assumed quasi-Dirac and the remaining neutrinos are Majorana states. In the case of inverse mass hierarchy, the lower bound on the neutrinoless double beta decay parameter m_ee is about two times that of the usual lower bound, within the range of sensitivity of the next generation of experiments.