Global fit to Higgs signal strengths and couplings and implications for extended Higgs sectors

TL;DR

This paper combines the latest Higgs data from LHC, Tevatron, and other experiments to constrain Higgs couplings and test extended Higgs sector models, providing a comprehensive framework for new physics searches.

Contribution

It introduces a method to use combined signal strength ellipses to constrain Higgs couplings and applies this to various extended Higgs sector models, enhancing the analysis of new physics.

Findings

Constraints on Higgs couplings to fermions and vector bosons.

Limits on new physics contributions to loop-induced Higgs processes.

Implications for extended Higgs models like 2HDM and Georgi-Machacek.

Abstract

The most recent LHC data have provided a considerable improvement in the precision with which various Higgs production and decay channels have been measured. Using all available public results from ATLAS, CMS and the Tevatron, we derive for each final state the combined confidence level contours for the signal strengths in the (gluon fusion + ttH associated production) versus (vector boson fusion + VH associated production) space. These "combined signal strength ellipses" can be used in a simple, generic way to constrain a very wide class of New Physics models in which the couplings of the Higgs boson deviate from the Standard Model prediction. Here, we use them to constrain the reduced couplings of the Higgs boson to up-quarks, down-quarks/leptons and vector boson pairs. We also consider New Physics contributions to the loop-induced gluon-gluon and photon-photon couplings of the Higgs, as well as invisible/unseen decays. Finally, we apply our fits to some simple models with an extended Higgs sector, in particular to Two-Higgs-Doublet models of Type I and Type II, the Inert Doublet model, and the Georgi-Machacek triplet Higgs model.