Rare top decay $t\rightarrow c\gamma$ in general THDM-III

TL;DR

This paper investigates the rare top quark decay $t\rightarrow c\gamma$ within the general THDM-III, calculating its branching ratio considering scalar mixing and estimating potential observable events at high luminosity.

Contribution

It provides the first detailed calculation of $Br(t\rightarrow c\gamma)$ in the general THDM-III with scalar mixing, including an estimate of observable events at collider experiments.

Findings

Branching ratio $Br(t\rightarrow c\gamma)$ around $10^{-8}$.

Estimated maximum of 18 observable events at 300 fb$^{-1}$ luminosity.

Scalar mixing significantly influences the decay rate.

Abstract

We study the decay $t\rightarrow c\gamma$ with flavor-changing neutral interactions in scalar sector of the type III Two Higgs Doublet Model (THDM-III) with mixing between neutral scalar fields as a result of considering the most general scalar potential. The branching ratio of the decay $Br(t\rightarrow c\gamma)$ is calculated as function of the mixing parameters and masses of the neutral scalar fields. We obtain a $Br(t\rightarrow c\gamma)$ of the order of $10^{-8}$ for the considered regions of the mixing parameters. Finally, one upper bound for the possible events is estimated to be $n=18$ by assuming a expected luminosity of the order of 300 $fb^{-1}$.