The Minimal Seesaw Model with a Modular $S_4$ Symmetry

TL;DR

This paper develops a supersymmetric minimal type-I seesaw model incorporating modular $S_4$ symmetry, explaining neutrino masses, flavor mixing, CP violation, and matter-antimatter asymmetry via resonant leptogenesis at a low scale, with testable predictions.

Contribution

It introduces a novel modular $S_4$ symmetry framework into the minimal seesaw model, linking flavor symmetry to leptogenesis and low-energy observables.

Findings

Successful explanation of matter-antimatter asymmetry via low-scale resonant leptogenesis.

Predictions for neutrino mass spectra and flavor mixing consistent with observations.

Constraints on model parameters from leptogenesis and low-energy data.

Abstract

In this paper, we incorporate the modular $S^{}_4$ flavor symmetry into the supersymmetric version of the minimal type-I seesaw model, in which only two right-handed neutrino singlets are introduced to account for tiny Majorana neutrino masses, and explore its implications for the lepton mass spectra, flavor mixing and CP violation. The basic idea is to assign two right-handed neutrino singlets into the unique two-dimensional irreducible representation of the modular $S^{}_4$ symmetry group. Moreover, we show that the matter-antimatter asymmetry in our Universe can be successfully explained via the resonant leptogenesis mechanism working at a relatively-low seesaw scale $\Lambda^{}_{\rm SS} \approx 10^7~{\rm GeV}$, with which the potential problem of the gravitino overproduction can be avoided. In this connection, we emphasize that the observed matter-antimatter asymmetry may lead to a stringent constraint on the parameter space and testable predictions for low-energy observables.