Fermion masses and mixings and charged lepton flavor violation in a 3-3-1 model with inverse seesaw

Abstract

We present a extension of the 3-3-1 gauge model supplemented by an $A_4$ flavor symmetry and cyclic discrete symmetries, including $Z_2$, $Z_2'$, $Z_3$, $Z_4$, $Z_7$ and $Z_{10}$. The model successfully reproduces the observed SM fermion mass hierarchies and mixing patterns in quark and lepton sectors. The smallness of the active neutrino masses is explained through an inverse seesaw mechanism, enabled by the introduction of right-handed and sterile Majorana neutrinos. In the quark sector, flavor-changing neutral currents (FCNCs) arise at tree level exclusively for up-type quarks via the new heavy neutral gauge boson exchange, leading to strong constraints from $D^0$ - $\bar{D}^0$ mixing. The charged lepton sector exhibits sizeable flavor-violating effects, especially in the $\mu \rightarrow e \gamma$ decay, mediated by loops involving heavy neutrinos, new charged gauge bosons as well as charged scalars. We perform a detailed numerical fit of fermion masses and mixing parameters and identify viable regions of parameter space consistent with experimental data on CKM and PMNS mixing matrices. The model predicts branching ratios for charged lepton flavor violating decays and $\mu$-$e$ conversion rates within the sensitivity of future experiments.