Higgs Decay Signal Strengths in an Extended 2HDM

The combined CMS and ATLAS analysis of $h\to Z\gamma$ reveals a $2\sigma$ excess over the Standard Model (SM) prediction, hinting at potential new physics. In contrast, the observed agreement of ${\mu }_{\gamma \gamma }$ with the SM imposes stringent constraints on such extension. In this context, we investigate a Two Higgs Doublet Model (2HDM) extended by a complex scalar singlet and a vector-like lepton (VLL). This framework successfully accommodates the Higgs decay signal strengths ${\mu }_{{}_{W{W}^{\star }}}$, ${\mu }_{Z\gamma }$, and ${\mu }_{\gamma \gamma }$ while also satisfying precision electroweak constraints, the observed experimental value of muon $g-2$, and bounds from LEP II data. We identify a viable region of parameter space that is consistent with all low energy data and current experimental limits on the Higgs decay signal strengths.