The neutral scalars of type-II 2HDM+S under the LHC

TL;DR

This paper investigates the collider signatures of the 2HDM+S model, a singlet extension of the 2HDM, by analyzing parameter spaces and experimental constraints, highlighting the potential of exotic decay channels.

Contribution

It provides a model-independent parametrization and explores the complementarity of search channels, identifying regions where exotic decays are particularly effective.

Findings

Exclusion regions are derived in various parameter spaces using current experimental data.

Exotic decay channels like A/H → Z h_S/ZA_S can probe large parts of the parameter space.

Moderate tanβ regions are especially accessible through these exotic channels.

Abstract

The 2HDM+S is a singlet extension of the Two-Higgs-Doublet Model (2HDM), which offers rich collider phenomenology. In this paper, we parametrize the 2HDM+S with the Higgs masses and mixing angles, which provide a model-independent framework to study the collider signature. Under five benchmark scenarios, we obtain the 95\% C.L. exclusion regions in the Type-II 2HDM+S parameter space by incorporating the SM-like 125~GeV Higgs precision measurements, beyond the Standard Model Higgs direct searches, $Z$-pole precision measurements and $B$-physics observables. We present the results in the Higgs boson masses vs $\tan\beta$, Higgs boson masses vs mixing angles, $\tan\beta$ vs mixing angles and doublet Higgs boson masses vs singlet Higgs boson mass parameter space. We explore the complementarity between direct and indirect Higgs searches, as well as conventional Higgs search channels and exotic Higgs search channels. Compared to the 2HDM scenarios, we find that exotic channels such as $A/H \rightarrow Z h_S/ZA_S$ can probe large part of the parameter spaces, especially for moderate $1<\tan\beta<7$ region where the conventional channels in the 2HDM cannot contribute much.