A4xSU(5) SUSY GUT of Flavour with Trimaximal Neutrino Mixing

Abstract

Recent T2K, MINOS and Double CHOOZ results, together with global fits of mixing parameters, indicate a sizeable reactor angle theta13 ~ 8 deg which, if confirmed, would rule out tri-bimaximal (TB) lepton mixing. Recently two of us studied the vacuum alignment of the Altarelli-Feruglio A4 family symmetry model including additional flavons in the 1' and 1" representations, leading to so-called "trimaximal" neutrino mixing and allowing a potentially large reactor angle. Here we show how such a model may arise from a Supersymmetric (SUSY) Grand Unified Theory (GUT) based on SU(5), leading to sum rule bounds |s| < thetaC/3, |a| < (r + thetaC/3)|cos delta|/2, where s,a,r parameterise the solar, atmospheric and reactor angle deviations from their TB mixing values, delta is the CP violating oscillation phase, and thetaC is the Cabibbo angle.