Degenerate neutrinos from a supersymmetric A_4 model

TL;DR

This paper analyzes a supersymmetric A_4 model that naturally produces quasi-degenerate, bi-large neutrino mixing, predicts maximal CP violation, and links slepton and lepton sectors, with testable predictions for neutrino mass and lepton decays.

Contribution

It provides a detailed study of a supersymmetric A_4 model that explains neutrino mixing, CP violation, and flavor structure, with specific predictions for lepton decay processes.

Findings

Neutrinos are quasi-degenerate and bi-largely mixed.

CP violation in the leptonic sector is maximal.

Predicted lower limit for tau -> mu gamma decay is 10^{-9}.

Abstract

We investigate the supersymmetric A_4 model recently proposed by Babu, Ma and Valle. The model naturally gives quasi-degenerate neutrinos that are bi-largely mixed, in agreement with observations. Furthermore, the mixings in the quark sector are constrained to be small, making it a complete model of the flavor structure. Moreover, it has the interesting property that CP-violation in the leptonic sector is maximal (unless vanishing). The model exhibit a close relation between the slepton and lepton sectors and we derive the slepton spectra that are compatible with neutrino data and the present bounds on flavor-violating charged lepton decays. The prediction for the branching ratio of the decay tau -> mu gamma has a lower limit of 10^{-9}. In addition, the overall neutrino mass scale is constrained to be larger than 0.3 eV. Thus, the model will be tested in the very near future.