SM Higgs boson and $t\rightarrow cZ$ decays in the 2HDM type III with CP violation

TL;DR

This paper investigates how the 2HDM type III with CP violation affects rare top decays, predicting potentially observable increases in decay rates for $t ightarrow cZ$ and $t ightarrow ch_1$, constrained by experimental data.

Contribution

It provides new calculations of rare top decay branching ratios within the 2HDM type III with CP violation, highlighting possible enhancements and parameter constraints.

Findings

$BR(t ightarrow c Z)$ can reach $10^{-3}$ with specific Higgs masses and $ aneta$

$BR(t ightarrow c h_1)$ can be as high as $10^{-2}$

Model parameters are constrained by current experimental measurements

Abstract

We compute the contributions to rare top decays $t\rightarrow cZ$ and $t\rightarrow ch_1$ from the scalar sector in the 2HDM type III with CP violation, where $h_1$ is the Standard Model Higgs boson. The branching ratio for $BR(t\rightarrow c Z)$ and $BR(t\rightarrow c h_1)$ are obtained as a function of the model parameters. In particular, the $BR(t\rightarrow c Z)$ can increase its value up to $10^{-3}$ for $\tan\beta= 1$ and masses for the additional Higgs bosons of $m_{h_2,h_3,H^\pm}\sim 0.5$ TeV. Meanwhile $BR(t\rightarrow c h_1)$ can reach values of the order of $\sim10^{-2}$. We constrain the model parameters (mixing angles of the neutral scalar fields in the CP violation context and $\tan\beta$) using the reported values of the signal strengths $R_{XX}$ and $b \rightarrow s \gamma$ process.