Measurable neutrino mass scale in <i>A₄ × SU(5)</i>

We propose a supersymmetric A4 × SU(5) model of quasidegenerate neutrinos which predicts the effective neutrino mass mee relevant for neutrinoless double beta decay to be proportional to the neutrino mass scale, thereby allowing its determination approximately independently of unknown Majorana phases. Such a natural quasidegeneracy is achieved by using A4 family symmetry (as an example of a non-Abelian family symmetry with real triplet representations) to enforce a contribution to the neutrino mass matrix proportional to the identity. Tribimaximal neutrino mixing as well as quark CP violation with α ≈ 90° and a leptonic CP phase δMNS ≈ 90° arise from the breaking of the A4 family symmetry by the vacuum expectation values of four “flavon” fields pointing in specific postulated directions in flavor space