A4 realization of the inverse seesaw mechanism: Neutrino masses, θ13 , and leptonic nonunitarity

Abstract

We provide an A 4 based flavor symmetric scenario to accommodate the inverse seesaw mechanism for explaining light neutrino masses and mixing. We find that the lepton mixing, in particular the tri-bimaximal mixing pattern and its deviation through nonzero θ 13 , is originated solely from the flavor structure of the lepton number violating contribution of the neutral lepton mass matrix. Here we discuss in detail how a nonzero value of θ 13 is correlated with the other parameters in the framework and its impact on the Dirac CP phase δ. We also analyze the non-unitarity effects on lepton mixing matrix and its implication in terms of the lepton flavor violating decays, etc.

$$A_4$$ A 4 realization of linear seesaw and neutrino phenomenology

“…The SM particle content has been extended by introducing three RH neutrinos, N R i , and three singlet fermions, S R i , along with the flavon fields (φ S , φ T , ξ , ξ , ρ, ρ ), to understand the flavor structure of the lepton mixing. The proposed model gives an almost similar result to [21] in the context of neutrino oscillation, but it has a different physics aspect in the case of heavy neutrinos. In [21], the active neutrinos get their mass through an inverse seesaw mechanism with the prediction of six nearly degenerate heavy neutrinos, but in our case there are three very different mass states with each state being nearly doubly degenerate.…”

“…The proposed model gives an almost similar result to [21] in the context of neutrino oscillation, but it has a different physics aspect in the case of heavy neutrinos. In [21], the active neutrinos get their mass through an inverse seesaw mechanism with the prediction of six nearly degenerate heavy neutrinos, but in our case there are three very different mass states with each state being nearly doubly degenerate. Furthermore, in our model the lightest heavy neutrino mass is assumed to be around 5 TeV and there will be two heavy neutrinos around this energy.…”

“…Such implications include non-unitarity and a possible CP violation effect, which can be tested at the currently running long-baseline (NOνA) or upcoming DUNE experiments. Since all the six heavy neutrinos are almost degenerate in [21], the non-unitarity effect will be large there, whereas in our case the effect will be small as discussed in Sect. 6.…”

“…We extend the SM symmetry with A 4 ×Z 4 ×Z 3 along with an extra global symmetry U (1) X , as discussed in Ref. [21]. The SM particle content has been extended by introducing three RH neutrinos, N R i , and three singlet fermions, S R i , along with the flavon fields (φ S , φ T , ξ , ξ , ρ, ρ ), to understand the flavor structure of the lepton mixing.…”

Probing sterile neutrinos in the framework of inverse seesaw mechanism through leptoquark productions

“…We have also proposed a same-sign dilepton signal region associated with multiple jets and missing energy that can be used to distinguish the the present scenario from the usual inverse seesaw extended SM.the sterile neutrino mass scale M R close to TeV, i.e., within the reach of LHC, with order one Yukawa coupling. This feature of the model leads to a plethora of testable phenomenological consequences [22][23][24][25][26][27][28][29][30][31][32] which have been studied quite extensively in the context of present and future collider experiments [33][34][35][36][37][38][39][40][41][42]. For the RH neutrino production through vector boson fusion and higher order corrections, see [43,44].…”