The one loop contribution to the lepton flavor violating decay h 0 → µτ of the SM-like neutral Higgs (LFVHD) in the 3-3-1 model with neutral lepton is calculated using the unitary gauge. We have checked in detail that the total contribution is exactly finite, and the divergent cancellations happen separately in two parts of active neutrinos and exotic heavy leptons. By numerical investigation, we have indicated that the one-loop contribution of the active neutrinos is very suppressed while that of exotic leptons is rather large. The branching ratio of the LFVHD strongly depends on the Yukawa couplings between exotic leptons and SU (3) L Higgs triplets. This ratio can reach 10 −5 providing large Yukawa couplings and constructive correlations of the SU (3) L scale (v 3 ) and the charged Higgs masses. The branching ratio decreases rapidly with the small Yukawa couplings and large v 3 .

We investigate the decays l i → l j γ , with l i = e, μ, τ in a general class of 3-3-1 models with heavy exotic leptons with arbitrary electric charges. We present full and exact analytical results keeping external lepton masses. As a by product, we perform numerical comparisons between exact results and approximate ones where the external lepton masses are neglected. As expected, we found that branching fractions can reach the current experimental limits if mixings and mass differences of the exotic leptons are large enough. We also found unexpectedly that, depending on the parameter values, there can be huge destructive interference between the gauge and Higgs contributions when the gauge bosons connecting the Standard Model leptons to the exotic leptons are light enough. This mechanism should be taken into account when using experimental constraints on the branching fractions to exclude the parameter space of the model.

The lepton flavor violating decay of the Standard Model-like Higgs (LFVHD) is discussed in the framework of the radiative neutrino mass model built in [17]. The branching ratio (BR) of the LFVHD are shown to reach 10 −5 in the most interesting region of the parameter space shown in [17]. The dominant contributions come from the singly charged Higgs mediations, namely the coupling of h ± 2 with exotic neutrinos. Furthermore, if doubly charged Higgs is heavy enough to allow the mass of h ± 2 around 1 TeV, the mentioned BR can reach 10 −4 . Besides, we have obtained that the large values of the Br(h → µτ ) leads to very small ones of the Br(h → eτ ), much smaller than various sensitivity of current experiments.

We study a seesaw model with A 4 flavor symmetry and the physics phenomenological consequences. After symmetry breaking, the model leads to the neutrino mixing matrix that satisfies the current data of neutrino oscillation experiments. We then study how the low energy CP violation parameter, J CP , associates with the Dirac CP violation phase δ. We also study the high energy CP violation associate with the decay of heavy right handed neutrino in leptogenesis process in order to explain the observed baryon asymmetry of the Universe, η B . Numerically, we find a correlation between J CP and η B through the high energy phases. It is shown that our prediction for J CP , and hence for the Dirac CP violating phase δ, for some high energy fixed parameters can be constrained by the current data of η B .

An extension of the two Higgs doublet model including inverse seesaw neutrinos and neutral Higgs bosons was constructed based on the A4 symmetry in order to explain the recent neutrino oscillation data. This model can distinguish two well-known normal and inverted order schemes of neutrino data once both the effective masses mβ in tritium beta decays and 〈m〉 in the neutrinoless double beta decay are observed. The lepton flavor violating decays of the charged leptons eb → eaγ, μ → 3e, the Standard model-like Higgs boson decays h → ebea, and the μ-e conversions in some nuclei are generated from loop corrections. The experimental data of the branching ratio Br(μ → eγ, 3e) predict that the upper bounds of Br(τ → μγ, eγ) and Br(h → eaeb) are much smaller than the planned experimental sensitivities. In contrast, the μ-e conversions are the promising signals for experiments.