Trimaximal mixing with predicted \theta_13 from a new type of constrained sequential dominance

TL;DR

This paper proposes a new class of neutrino mixing models that predict a specific reactor angle , relate it to neutrino mass ratios, and connect leptogenesis with the Dirac CP phase, all within a constrained sequential dominance framework.

Contribution

Introduction of a novel constrained sequential dominance model with specific vacuum alignments that predict  and link leptogenesis to the Dirac CP phase.

Findings

Predict   5b0 - 6b0 based on neutrino mass ratios.

Derive a sum rule relating , 3, and the CP phase .

Show leptogenesis is unsuppressed and directly connected to the Dirac CP phase.

Abstract

Following the recent T2K indication of a sizeable reactor angle, we present a class of models which fix \theta_{13} while preserving trimaximal solar mixing. The models are based on a new type of constrained sequential dominance involving new vacuum alignments, along the (1,2,0)^T or (1,0,2)^T directions in flavour space. We show that such alignments are easily achieved using orthogonality, and may replace the role of the subdominant flavon alignment (1,1,1)^T in constrained sequential dominance. In such models, with a normal hierarchical spectrum, the reactor angle is related to a ratio of neutrino masses by \theta_{13} = \frac{\sqrt{2}}{3}\frac{m^\nu_2}{m^\nu_3}, leading to \theta_{13} \sim 5^\circ - 6^\circ, while the atmospheric angle is given by the sum rule \theta_{23} \approx 45^\circ + \sqrt{2} \theta_{13} \cos \delta. We find that leptogenesis is unsuppressed due to the violation of form dominance and that the CP violating phase responsible for leptogenesis is precisely equal to the Dirac CP phase \delta, providing a direct link between leptogenesis and neutrino mixing in this class of models.