Revisiting the Flavor Model and Leptogenesis

Abstract We revisit a supersymmetric flavor model, based on the symmetries of $SU(2)_L \times A_4 \times Z_3 \times U(1)_R$, which extends the original Altarelli and Feruglio construction by introducing flavon and driving superfields responsible for the spontaneous breaking of the flavor symmetry in order to obtain a nonzero reactor angle. Vacuum alignments of the flavon fields are achieved through the minimization of the scalar potential derived from the superpotential. This setup leads to specific mass matrices for the charged leptons and neutrinos that are consistent with current experimental data, including the measured values of the lepton mixing angles and neutrino mass squared differences. We investigate whether the model can simultaneously accommodate successful thermal leptogenesis. In particular, we analyze the CP asymmetry generated by the decay of heavy Majorana neutrinos, the resulting lepton asymmetry, and its conversion to the baryon asymmetry through the electroweak sphalerons. We find, however, that the CP asymmetry is zero in the leading order of the model since the Dirac neutrino mass matrix has simple texture. Then we consider the next-to-leading order in Yukawa interactions of the Dirac neutrinos. As a result, we can realize the baryon asymmetry of the universe at the present universe. By numerically scanning the parameter space, we identify the regions consistent with both neutrino oscillation data and the observed baryon asymmetry. In the specific case such that one of the couplings for the right-handed Majorana neutrinos is a real parameter, the predicted lightest neutrino mass is at least 5 meV and 15 meV for the normal and inverted neutrino mass hierarchies, respectively. In addition, the range of the Majorana phases may be tested in future experiments.