Neutrino Mixing and Leptonic CP Violation from $S_4$ and Generalised CP Symmetries

TL;DR

This paper explores models of neutrino mixing based on $S_4$ flavor symmetry combined with generalized CP symmetry, predicting specific CP violation phases and neutrinoless double beta decay parameters.

Contribution

It classifies viable neutrino mixing patterns within $S_4$ and generalized CP symmetry frameworks, providing explicit predictions for CP phases and decay observables.

Findings

Predicted ranges for Dirac CP violation phase

Predicted Majorana CP phases

Constraints on neutrinoless double beta decay mass

Abstract

We consider a class of models of neutrino mixing with $S_4$ flavour symmetry and generalised CP symmetry, broken to $Z_2$ and $Z_2 \times {\rm CP}$ residual symmetries in the charged lepton and neutrino sectors, respectively. In this scheme, and up to discrete ambiguities, the neutrino mixing matrix is determined by two angles and one phase. We classify the phenomenologically viable mixing patterns, deriving predictions for the Dirac and Majorana CPV phases and for the effective Majorana mass in neutrinoless double beta decay.