Effects of Two Inert Scalar Doublets on Higgs Interactions and Electroweak Phase Transition

TL;DR

This paper examines how two inert scalar doublets charged under a dark gauge symmetry influence Higgs boson interactions, electroweak precision parameters, and the nature of the electroweak phase transition, with implications for future collider measurements.

Contribution

It introduces a model with two inert scalar doublets affecting Higgs properties and electroweak phase transition, providing new insights into dark sector interactions and Higgs phenomenology.

Findings

Inert scalars modify Higgs decay modes and couplings.

The model predicts a strongly first-order electroweak phase transition.

Correlations between phase transition strength and Higgs trilinear coupling modifications.

Abstract

We study some implications of the presence of two inert scalar doublets which are charged under a dark Abelian gauge symmetry. Specifically, we investigate the effects of the new scalars on oblique electroweak parameters and on the interactions of the 125 GeV Higgs boson, especially its decay modes $h\to\gamma\gamma,\gamma Z$, and trilinear coupling, all of which will be probed with improved precision in future Higgs measurements. Moreover, we explore how the inert scalars may give rise to strongly first-order electroweak phase transition and also show its correlation with sizable modifications to the Higgs trilinear coupling.