Higgs masses and couplings in the general 2HDM with unitarity bounds

TL;DR

This paper analyzes the parameter space of the general two Higgs doublet model under unitarity and stability constraints, exploring Higgs masses and couplings consistent with experimental bounds and potential phenomenological implications.

Contribution

It provides a comprehensive analysis of the 2HDM parameter space considering unitarity, stability, and experimental constraints, highlighting possible deviations in Higgs couplings from the Standard Model.

Findings

Cubic Higgs coupling can be up to 1.6 times the SM value.

Quartic Higgs coupling can be up to four times the SM value.

Cubic coupling can be zero or negative, quartic always positive.

Abstract

We investigate the general two Higgs doublet model imposing both the unitarity conditions and the bounded-from-below conditions. Both types of conditions restrict the ranges of the parameters of the scalar potential. We study the model in the Higgs basis, i.e. in the basis for the scalar doublets where only one doublet has vacuum expectation value. We use the experimental bounds on the oblique parameter T, to produce scalar particles with masses and cubic and quartic couplings of the Higgs in agreement with the phenomenology. The numerical calculations show that the cubic coupling may be up to 1.6 times larger than in the Standard Model, but it may also be zero or even negative. The quartic coupling is always positive and may be up to four times larger than in the Standard Model.