Phenomenology of the Georgi-Machacek model at future electron-positron colliders

TL;DR

This paper explores how future electron-positron colliders can detect and measure exotic Higgs bosons predicted by the Georgi-Machacek model, focusing on their signatures, mass determination, and synergy with LHC searches.

Contribution

It demonstrates the potential of ILC to identify and precisely measure the 5-plet Higgs bosons, enhancing understanding of custodial symmetry in the model.

Findings

Neutral and singly-charged Higgs bosons can be identified via $W^+W^-Z$ final states.

Mass degeneracy of the 5-plet Higgs bosons can be tested with high precision.

Synergy with LHC searches improves the overall study of these exotic Higgs states.

Abstract

We study the phenomenology of the exotic Higgs bosons in the Georgi-Machacek model at future electron-positron colliders such as the International Linear Collider (ILC), assuming the collision energies of 500 GeV and 1 TeV. We show that the existence of the neutral and singly-charged Higgs bosons in the 5-plet representation under the custodial $SU(2)_V$ symmetry can be readily identified by studying various energy and invariant mass distributions of the $W^+W^-Z$ final state. Moreover, their masses can be determined with sufficiently high precision to test the mass degeneracy, a feature due to the custodial symmetry of the model. A synergy between such searches at the ILC and the doubly-charged Higgs search at the LHC will make the 5-plet Higgs boson study more comprehensive.