Revisiting Flavor Model and Leptogenesis

TL;DR

This paper revisits a supersymmetric flavor model to explain neutrino mixing and baryon asymmetry, analyzing the conditions under which leptogenesis can successfully occur within the model's framework.

Contribution

It introduces flavon and driving superfields into a supersymmetric flavor model to achieve realistic neutrino mixing and explores the potential for successful thermal leptogenesis.

Findings

The CP asymmetry in the leading order is zero, requiring next-to-leading order corrections.

The model can generate the observed baryon asymmetry with parameter tuning.

Predicted lightest neutrino mass is at least 5 meV (normal hierarchy) and 15 meV (inverted hierarchy).

Abstract

We revisit a supersymmetric flavor model based on the symmetries $SU(2)_L \times A_4 \times Z_3 \times U(1)_R$, 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 non-zero reactor angle. The vacuum alignments of 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 in the decay of heavy Majorana neutrinos, the resulting lepton asymmetry, and its conversion to the baryon asymmetry through the electroweak sphalerons. However the CP asymmetry is zero, since the Dirac neutrino mass matrix is simple texture in the leading order for our model. Then we consider the next-to-leading order in Yukawa interactions of the Dirac neutrinos. Therefore, 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 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.