$h \rightarrow Z \gamma$ in the complex two Higgs doublet model

TL;DR

This paper investigates the decay of a mixed scalar-pseudoscalar Higgs-like particle into Z gamma within the complex two Higgs doublet model, analyzing how current measurements constrain the pseudoscalar component and implications for Yukawa couplings.

Contribution

It provides a detailed calculation of the h → Z γ decay in the complex 2HDM and explores how existing data restricts the pseudoscalar admixture in the Higgs-like particle.

Findings

Current measurements constrain the pseudoscalar component of the Higgs-like particle.

A SM-like h → Z γ rate limits the pseudoscalar admixture in the model.

Discussion on the sign of bottom Yukawa coupling in Type II models.

Abstract

The latest LHC data confirmed the existence of a Higgs-like particle and made interesting measurements on its decays into $\gamma \gamma$, $Z Z^\ast$, $W W^\ast$, $\tau^+ \tau^-$, and $b \bar{b}$. It is expected that a decay into $Z \gamma$ might be measured at the next LHC round, for which there already exists an upper bound. The Higgs-like particle could be a mixture of scalar with a relatively large component of pseudoscalar. We compute the decay of such a mixed state into $Z \gamma$, and we study its properties in the context of the complex two Higgs doublet model, analysing the effect of the current measurements on the four versions of this model. We show that a measurement of the $h \rightarrow Z \gamma$ rate at a level consistent with the SM can be used to place interesting constraints on the pseudoscalar component. We also comment on the issue of a wrong sign Yukawa coupling for the bottom in Type II models.