Bounds on Higgs-Portal models from the LHC Higgs data

TL;DR

This paper uses the latest LHC Higgs data to constrain Higgs-portal models involving a singlet scalar that mixes with the SM Higgs, finding current data slightly favors the Standard Model and setting bounds on model parameters.

Contribution

It provides the first comprehensive global fit to Higgs-portal models using updated LHC data, constraining the mixing angle and total width modifications.

Findings

Current data slightly favors the Standard Model over Higgs-portal models.

Constraints: cos(α) ≥ 0.86 and ΔΓ_tot ≤ 1.9 MeV at 95% CL.

Higgs-portal models are tightly constrained by recent LHC measurements.

Abstract

In a number of Higgs-portal models, an $SU(2)$ isospin-singlet scalar boson generically appears at the electroweak scale and can mix with the Standard Model (SM) Higgs boson with a mixing angle $\alpha$. This singlet scalar boson can have renormalizable couplings to a pair of dark matter particles, vectorlike leptons or quarks, or new gauge bosons, thereby modifying the Higgs signal strengths in a nontrivial way. In this work, we perform global fits to such models using the most updated LHC Higgs-boson data and discuss the corresponding implications on Higgs-portal-type models. In particular we find that the current LHC Higgs-boson data slightly favors the SM over the Higgs-portal singlet-scalar models, which has to be further examined using the upcoming LHC Higgs-boson data. Finally the Higgs-portal models are constrained as follows: $\cos\alpha \gtrsim 0.86$ and $\Delta \Gamma_{\rm tot} \lesssim 1.9$ MeV at 95 \% CL.