CP-violation and its implications in a complex singlet extension of 2HDM

TL;DR

This paper explores CP-violation in a complex singlet extension of the 2HDM, examining its implications for dark matter, collider detection, and the CP-properties of the Higgs boson, with a focus on experimental constraints and future prospects.

Contribution

It introduces an additional CP-violation source in the complex singlet extension of 2HDM, expanding the model's parameter space and its testability at future colliders.

Findings

Enhanced CP-violation source compared to 2HDM.

Dark matter constraints significantly influence the model.

Detection prospects of CP-phase are highly model-dependent.

Abstract

We investigate CP-violation in the complex singlet extension of the general Two Higgs Doublet Model (2HDM) with Yukawa alignment condition. We first explore the possibility of explicit CP-violation in the extended scalar sector while the 125 GeV Higgs remains exactly Standard Model (SM)-like. We identify an additional source of CP violation in the complex singlet extension compared to the 2HDM, which allows this model a substantially greater freedom in satisfying the stringent EDM constraints. We also incorporate dark matter in this model and investigate the impacts of constraints from the dark sector on the model parameter space and its interplay with CP-violation phases. We further explore the possibility of detecting such a scenario at future collider experiments via CP-violating trilinear couplings among the non-standard scalars. Finally, we also deviate from the exact alignment limit and investigate the CP-properties of the observed Higgs boson in the context of our model. We demonstrate the strong model-dependent nature of the detection prospects of the CP-phase of the Higgs boson at future experiments, exploring both fermion couplings as well as the trilinear self-coupling of the Higgs boson.