Updated constraints on Georgi-Machacek model, and its electroweak phase transition and associated gravitational waves

TL;DR

This paper updates the parameter space of the Georgi-Machacek model considering current constraints, analyzes its potential for strong electroweak phase transitions, and predicts detectable gravitational wave signals and collider signatures.

Contribution

It provides the first comprehensive update of the GM model's parameter space with recent data and explores its implications for electroweak phase transitions and gravitational wave detection.

Findings

Only one-step phase transition is phenomenologically viable.

Most gravitational wave signals from the model are detectable by proposed experiments.

Predictions include promising collider signatures such as di-Higgs and exotic scalar productions.

Abstract

With theoretical constraints such as perturbative unitarity and vacuum stability conditions and updated experimental data of Higgs measurements and direct searches for exotic scalars at the LHC, we perform an updated scan of the allowed parameter space of the Georgi-Machacek (GM) model. With the refined global fit, we examine the allowed parameter space for inducing strong first-order electroweak phase transitions (EWPTs) and find only the one-step phase transition is phenomenologically viable. Based upon the result, we study the associated gravitational wave (GW) signals and find most of which can be detected by several proposed experiments. We also make predictions on processes that may serve as promising probes to the GM model in the near future at the LHC, including the di-Higgs productions and several exotic scalar production channels.