Contribution of heavy neutrinos to decay of standard-model-like Higgs boson $h\rightarrow \mu\tau$ in a 3-3-1 model with additional gauge singlets

TL;DR

This paper explores how heavy neutrinos in an extended 3-3-1 model influence lepton-flavor-violating Higgs decays, revealing potential branching ratios near current experimental limits through detailed neutrino mass matrix analysis.

Contribution

It introduces a detailed analysis of heavy neutrino effects on Higgs lepton-flavor-violating decays within an improved 3-3-1 model, highlighting the impact of different neutrino mass matrix configurations.

Findings

Heavy neutrinos can induce Higgs decay branching ratios close to 10^-3.

Lepton-flavor-violating decays like $h ightarrow au ightarrow au$ can reach experimental sensitivity.

Parametric regions exist where constraints from $ ext{Br}( au ightarrow ext{something})$ are satisfied.

Abstract

In the framework of the improved version of the 3-3-1 models with right-handed neutrinos, which is added to the Majorana neutrinos as new gauge singlets, the recent experimental neutrino oscillation data is completely explained through the inverse seesaw mechanism. We show that the major contributions to $Br(\mu\rightarrow e\gamma)$ are derived from corrections at 1-loop order of heavy neutrinos and bosons. But, these contributions are sometimes mutually destructive, creating regions of parametric spaces where the experimental limits of $Br(\mu\rightarrow e\gamma)$ are satisfied. In these regions, we find that $Br(\tau\rightarrow \mu\gamma)$ can achieve values of $10 ^{- 10}$ and $Br(\tau\rightarrow e\gamma)$ may even reach values of $10 ^{- 9}$ very close to the upper bound of the current experimental limits. Those are ideal areas to study lepton-flavor-violating decays of the standard- model- like Higgs boson ($h_1^0$). We also pointed out that the contributions of heavy neutrinos play an important role to change $Br(h_1^0\rightarrow \mu\tau)$, this is presented through different forms of mass mixing matrices ($M_R$) of heavy neutrinos. When $M_R \sim diag(1,1,1)$, $Br(h_1^0\rightarrow \mu\tau)$ can get a greater value than the cases $M_R \sim diag(1,2,3)$ and $M_R \sim diag(3,2,1)$ and the largest that $Br(h_1^0\rightarrow \mu\tau)$ can reach is very close $10 ^{-3}$.