Type II seesaw models with modular $A_4$ symmetry

TL;DR

This paper explores type-II seesaw models with modular $A_4$ symmetry in a supersymmetric context, fitting neutrino oscillation data and predicting CP phases, neutrino masses, and decay branching ratios of doubly charged scalars.

Contribution

It introduces a classification of type-II seesaw models with modular $A_4$ symmetry based on representation assignments and modular weights, providing a framework for neutrino mass and decay predictions.

Findings

Identified parameter sets fitting neutrino oscillation data.

Predicted CP violating phases and lightest neutrino mass.

Estimated branching ratios for doubly charged scalar decays.

Abstract

We discuss type-II seesaw models adopting modular $A_4$ symmetry in supersymmetric framework. In our approach, the models are classified by the assignment of $A_4$ representations and modular weights for leptons and triplet Higgs fields. Then neutrino mass matrix is characterized by modulus $\tau$ and two free parameters. Carrying out numerical analysis, we find allowed parameter sets which can fit the neutrino oscillation data. For the allowed parameter sets, we obtain the predictions in neutrino sector such as CP violating phases and the lightest neutrino mass. Finally we also show the predictions for the branching ratios of doubly charged scalar boson focusing on the case where the doubly charged scalar boson dominantly decays into charged leptons.