Models with Extended Higgs Sectors at Future $e^+ e^-$ Colliders

TL;DR

This paper explores various extended Higgs sector models beyond the Standard Model and assesses how future electron-positron colliders can help distinguish their features through precise measurements of Higgs boson properties.

Contribution

It compares different extended Higgs models and evaluates the potential of future colliders to identify or constrain these models via Higgs coupling precision.

Findings

Future colliders can constrain singlet or pseudoscalar admixtures to the 125 GeV Higgs.

Predictions show the ability to differentiate models based on scalar production and decay rates.

Even without discovering new scalars, colliders will clarify the Higgs boson's nature.

Abstract

We discuss the phenomenology of several Beyond the Standard Model (SM) extensions that include extended Higgs sectors. The models discussed are: the SM extended by a complex singlet field (CxSM), the 2-Higgs-Doublet Model with a CP-conserving (2HDM) and a CP-violating (C2HDM) scalar sector, the singlet extension of the 2-Higgs-Doublet Model (N2HDM), and the Next-to-Minimal Supersymmetric SM extension (NMSSM). All the above models have at least three neutral scalars, with one being the 125 GeV Higgs boson. This common feature allows us to compare the production and decay rates of the other two scalars and therefore to compare their behaviour at future electron-positron colliders. Using predictions on the expected precision of the 125 GeV Higgs boson couplings at these colliders we are able to obtain the allowed admixtures of either a singlet or a pseudoscalar to the observed 125 GeV scalar. Therefore, even if no new scalar is found, the expected precision at future electron-positron colliders, such as CLIC, will certainly contribute to a clearer picture of the nature of the discovered Higgs boson.