The three- and four-Higgs couplings in the general two-Higgs-doublet model

TL;DR

This paper derives universal unitarity and bounded-from-below bounds on scalar masses and couplings in the general two-Higgs-doublet model, applicable across all variants, and compares these bounds with other scalar extensions of the Standard Model.

Contribution

It provides the first comprehensive bounds on the scalar sector of the general 2HDM in the Higgs basis, applicable to all 2HDMs and compares them with other scalar extensions.

Findings

Bounds on scalar masses and couplings derived

Comparison with bounds in singlet-extended models

Results valid for all 2HDMs

Abstract

We apply the unitarity bounds and the bounded-from-below (BFB) bounds to the most general scalar potential of the two-Higgs-doublet model (2HDM). We do this in the Higgs basis, i.e. in the basis for the scalar doublets where only one doublet has vacuum expectation value. In this way we obtain bounds on the scalar masses and couplings that are valid for all 2HDMs. We compare those bounds to the analogous bounds that we have obtained for other simple extensions of the Standard Model (SM), namely the 2HDM extended by one scalar singlet and the extension of the SM through two scalar singlets.