Neutral Higgs decays $H\to Z\gamma ,\gamma \gamma$ in 3-3-1 models

Abstract

The significance of new physics appearing in the loop-induced decays of neutral Higgs bosons into pairs of dibosons $\gamma \gamma$ and $Z\gamma$ will be discussed in the framework of the 3-3-1 models based on a recent work~\cite{Okada:2016whh}, where the Higgs sector becomes effectively the same as that in the two Higgs doublet models (2HDM) after the first symmetry breaking from $SU(3{)}_L$ scale into the electroweak scale. For large $SU(3{)}_L$ scale $v_3\simeq 10$ TeV, dominant one-loop contributions to the two decay amplitudes arise from only the single charged Higgs boson predicted by the 2HDM, leading to that experimental constraint on the signal strength ${\mu }_{\gamma \gamma }^{331}$ of the Standard Model-like Higgs boson decay $h\to \gamma \gamma$ will result in a strict upper bound on the signal strength ${\mu }_{Z\gamma }^{331}$ of the decay $h\to Z\gamma$. For a particular model with lower $v_3$ around 3 TeV, contributions from heavy charged gauge and Higgs bosons may have the same order, therefore may give strong destructive or constructive correlations. As a by-product, a deviation from the SM prediction $|{\mu }_{\gamma \gamma }^{331}-1|\le 0.04$ still allows $|{\mu }_{Z\gamma }^{331}-1|$ to reach values near 0.1. We also show that there exists an $CP$-even neutral Higgs boson $h_3^0$ predicted by the 3-3-1 models, but beyond the 2HDM, has an interesting property that the branching ratio Br$(h_3^0\to \gamma \gamma )$ is very sensitive to the parameter $\beta$ used to distinguish different 3-3-1 models.

Comments: Version accepted for publication in PRD