A4 models of tri-bimaximal-reactor mixing

TL;DR

This paper presents an A4 symmetry-based model that accurately predicts neutrino mixing angles, including a sizeable reactor angle, using the tri-bimaximal-reactor (TBR) ansatz and type I seesaw mechanism.

Contribution

It introduces an explicit A4 model implementing TBR mixing with small correction coefficients, aligning well with recent experimental data.

Findings

Accurately predicts neutrino mixing angles including theta_13 ~ 8°

Uses type I seesaw mechanism with vacuum alignment

Second order corrections to mixing angles are small

Abstract

Recent results from T2K, MINOS and Double CHOOZ all indicate a sizeable reactor angle theta_13 which would rule out conventional tri-bimaximal lepton mixing. However, it is possible to maintain the tri-bimaximal solar and atmospheric mixing angle predictions, theta_12 ~ 35 degrees, theta_23 ~ 45 degrees even for a quite sizeable reactor angle theta_13 ~ 8 degrees, using an ansatz called tri-bimaximal-reactor (TBR) mixing proposed by one of us some time ago. We propose an explicit A4 model of leptons based on the type I seesaw mechanism at both the effective and the renormalisable level which, together with vacuum alignment, leads to surprisingly accurate TBR neutrino mixing, with the second order corrections to mixing angles having small coefficients.