A Simplest A4 Model for Tri-Bimaximal Neutrino Mixing

TL;DR

This paper introduces a minimal $A_4$ see-saw model for neutrino mixing that naturally produces Tri-Bimaximal mixing and predicts a measurable $ heta_{13}$ angle, with implications for neutrino phenomenology.

Contribution

It presents a simplified $A_4$ model for neutrino mixing that does not require Froggatt-Nielsen symmetry, achieving exact Tri-Bimaximal mixing at leading order.

Findings

Exact Tri-Bimaximal mixing at leading order.

Predicted $ heta_{13}$ within experimental sensitivity.

Detailed analysis of neutrino spectrum and phenomenology.

Abstract

We present a see-saw $A_4$ model for Tri-Bimaximal mixing which is based on a very economical flavour symmetry and field content and still possesses all the good features of $A_4$ models. In particular the charged lepton mass hierarchies are determined by the $A_4\times Z_4$ flavour symmetry itself without invoking a Froggatt-Nielsen U(1) symmetry. Tri-Bimaximal mixing is exact in leading order while all the mixing angles receive corrections of the same order in next-to-the-leading approximation. As a consequence the predicted value of $\theta_{13}$ is within the sensitivity of the experiments which will take data in the near future. The light neutrino spectrum, typical of $A_4$ see-saw models, with its phenomenological implications, also including leptoproduction, is studied in detail.