Global fits in the Georgi-Machacek model

TL;DR

This paper performs a comprehensive global fit of the Georgi-Machacek model, combining experimental Higgs data and theoretical constraints to limit parameters and identify key decay channels of new scalars.

Contribution

It provides the first full global fit of the Georgi-Machacek model, constraining mixing angles, mass differences, and decay widths using recent data.

Findings

Strong limits on scalar mixing angles and mass differences.

Current data allows for a sign-flipped Higgs coupling, but heavy Higgs states are not supported.

Identified dominant decay channels and bounds on branching ratios.

Abstract

Off the beaten track of scalar singlet and doublet extensions of the Standard Model, triplets combine an interesting LHC phenomenology with an explanation for neutrino masses. The Georgi-Machacek model falls into this category, but it has never been fully explored in a global fit. We use the {\texttt{HEPfit}} package to combine recent experimental Higgs data with theoretical constraints and obtain strong limits on the mixing angles and mass differences between the heavy new scalars as well as their decay widths. We also find that the current signal strength measurements allow for a Higgs to vector boson coupling with an opposite sign to the Standard Model, but this possibility can be ruled out by the lack of direct evidence for heavy Higgs states. For these hypothetical particles, we identify the dominant decay channels and extract bounds on their branching ratios from the global fit, which can be used to single out the decay patterns relevant for the experimental searches.