Hybrid Seesaw Neutrino Masses with A₄ Family Symmetry

الأصل · EN

We consider the scenario in which neutrino data are explained by the interplay of type I and II seesaw terms in the Majorana neutrino mass matrix Mν= Mₗ - MD Mᵣ⁻¹ MDᵗ. We construct a predictive model with Mₗ proportional to the unit matrix, 3 diagonal texture zeros in Mᵣ, and MD diagonal. We show how this pattern can be maintained by the non-Abelian discrete symmetry A₄, and discuss its phenomenological consequences. It turns out that the two types of seesaw give contributions of the same order to Mν. In the CP conserving case, we find θ₁₃≈ 2/(2θ₂₃ 2θ₁₂) and we predict inverted (normal) ordering of the mass spectrum for ²θ₁₂ < 0.5 (>0.5).