Dark matter, electroweak phase transition and gravitational wave in the type-II two-Higgs-doublet model with a singlet scalar field

TL;DR

This paper investigates the potential for a strongly first order electroweak phase transition and detectable gravitational waves within a specific two-Higgs-doublet model with a singlet scalar dark matter candidate, considering experimental constraints.

Contribution

It identifies parameter regions in the model that allow for a strong electroweak phase transition and predicts gravitational wave signals within future detector sensitivities.

Findings

Dark matter mass and heavy Higgs mass constrained by LHC and dark matter data.

Parameter space for strong first order phase transition identified.

Predicted gravitational wave signals could be detected by future experiments.

Abstract

In the framework of type-II two-Higgs-doublet model with a singlet scalar dark matter $S$, we study the dark matter observables, the electroweak phase transition, and the gravitational wave signals by such strongly first order phase transition after imposing the constraints of the LHC Higgs data. We take the heavy CP-even Higgs $H$ as the only portal between the dark matter and SM sectors, and find the LHC Higgs data and dark matter observables require $m_S$ and $m_H$ to be larger than 130 GeV and 360 GeV for $m_A=600$ GeV in the case of the 125 GeV Higgs with the SM-like coupling. Next, we carve out some parameter space where a strongly first order electroweak phase transition can be achieved, and find benchmark points for which the amplitudes of gravitational wave spectra reach the sensitivities of the future gravitational wave detectors.