Compatibility of θ 13 and the Type I seesaw model with A 4 symmetry

Abstract

Abstract We derive formulae for neutrino masses and mixing angles in a type I seesaw framework with an underlying A 4 flavor symmetry. In particular, the Majorana neutrino mass matrix includes contributions from an A 4 triplet, 1, 1′, and 1′′ flavon fields. Using these formulae, we constrain the general A 4 parameter space using the updated global fits on neutrino mixing angles and mass squared differences, including results from the Daya Bay and RENO experiments, and we find predictive relations among the mixing parameters for certain choices of the triplet vacuum expectation value. In the normal hierarchy case, sizable deviation from maximal atmospheric mixing is predicted, and such deviation is strongly correlated with the value of θ13 in the range of ~ (8 − 10)◦. On the other hand, such deviation is negligible and insensitive to θ13 in the inverted mass hierarchy case. We also show expectations for the Dirac CP phase resulting from the parameter scan. Future refined measurements of neutrino mixing angles will test these predicted correlations and potentially show evidence for particular triplet vev patterns.