Inverse See-Saw Mechanism with $\mathbf{S}_{3}$ flavor symmetry

TL;DR

This paper explores an inverse see-saw mechanism with S3 flavor symmetry in a B-L gauge model, analyzing neutrino mixing, charged lepton flavor violation, and neutrinoless double beta decay, providing new insights into neutrino mass and mixing patterns.

Contribution

It introduces an S3 × Z2 discrete symmetry in a B-L model with inverse see-saw, detailing its effects on neutrino mixing, CLFV, and neutrinoless double beta decay, with analytical and numerical results.

Findings

Neutrino mixing follows Cobimaximal pattern with deviations.

Charged lepton flavor violation rates constrain the model.

Effective neutrino mass m_ee remains below GERDA bounds.

Abstract

The current neutrino experiments provide an opportunity for testing the inverse see-saw mechanism through charged lepton flavor violating processes and neutrinoless double beta decay. Motivated by this, in this paper we study the $\mathbf{S}_{3}\otimes \mathbf{Z}_{2}$ discrete symmetry in the $B-L$ gauge model where the active light neutrino mass matrix comes from the aforementioned mechanism. In this framework, the effect of complex vacuum expectation values of the Higgs doublets on the fermion masses is explored and, under certain assumptions on the Yukawa couplings, we find that the neutrino mixing is controlled by the Cobimaximal pattern, but a sizeable deviation from the charged lepton sector breaks the well known predictions on the atmospheric angle ($45^{\circ}$) and the Dirac CP-violating phase ($-90^{\circ}$). In addition, due to the presence of heavy neutrinos at the $TeV$ scale, charged lepton flavor violation (CLFV) and neutrinoless double beta decay get notable contributions. Analytical formulae for these observables are obtained, and then a numerical calculation allows to fit quite well the lepton mixing for the normal and inverted hierarchies, however, the branching ratios decay values for CLFV disfavors the latter one. Along with this, the region of parameter space for the $m_{ee}$ effective neutrino mass lies below the GERDA bounds for both the normal and inverted hierarchies. On the other hand, with a particular benchmark, the quark mass matrices are found to have textures that allow to fit with great accuracy the CKM mixing matrix.