Viable low-scale model with Universal and Inverse Seesaw Mechanisms

Abstract

We formulate a viable low-scale seesaw model, where the masses for the standard model (SM) charged fermions lighter than the top quark emerge from a universal seesaw mechanism mediated by charged vectorlike fermions. The small light active neutrino masses are produced from an inverse seesaw mechanism mediated by right-handed Majorana neutrinos. Our model is based on the $A_{4} $ family symmetry, supplemented by cyclic symmetries, whose spontaneous breaking produces the observed pattern of SM fermion masses and mixings. The model can accommodate the muon and electron anomalous magnetic dipole moments and predicts strongly suppressed $μ\rightarrow eγ$ and $τ\rightarrow μγ$ decay rates, but allows a $τ\rightarrow eγ$ decay within the reach of the forthcoming experiments.