A Minimal Model of Neutrino Flavor

TL;DR

This paper introduces the smallest realistic supersymmetric neutrino flavor model based on the T7 group, naturally predicting tribimaximal mixing and accommodating recent experimental measurements of the reactor angle.

Contribution

It presents a minimal T7-based supersymmetric model that avoids extra shaping symmetries and naturally predicts neutrino mixing patterns consistent with recent data.

Findings

Predicts tribimaximal mixing at leading order

NLO corrections align with recent reactor angle measurements

Controls deviations of other mixing angles in UV completion

Abstract

Models of neutrino mass which attempt to describe the observed lepton mixing pattern are typically based on discrete family symmetries with a non-Abelian and one or more Abelian factors. The latter so-called shaping symmetries are imposed in order to yield a realistic phenomenology by forbidding unwanted operators. Here we propose a supersymmetric model of neutrino flavor which is based on the group T7 and does not require extra Z_N or U(1) factors, which makes it the smallest realistic family symmetry that has been considered so far. At leading order, the model predicts tribimaximal mixing which arises completely accidentally from a combination of the T7 Clebsch-Gordan coefficients and suitable flavon alignments. Next-to-leading order (NLO) operators break the simple tribimaximal structure and render the model compatible with the recent results of the Daya Bay and Reno collaborations which have measured a reactor angle of around 9 degrees. Problematic NLO deviations of the other two mixing angles can be controlled in an ultraviolet completion of the model.