Type-II see-saw: searching the LHC elusive low-mass triplet-like Higgses at $e^-e^+$ colliders

TL;DR

This paper explores search strategies at future electron-positron colliders to detect low-mass triplet-like Higgs bosons that are currently beyond the reach of LHC searches, potentially enabling discovery of these particles.

Contribution

It proposes new search methods at 500 GeV and 1 TeV colliders to detect elusive low-mass triplet-like Higgses not accessible by current LHC experiments.

Findings

A significant part of the parameter space can be discovered with 5σ significance.

Early data from future colliders could reveal these Higgses.

Certain mass ranges as low as 200 GeV are still viable for detection.

Abstract

While the triplet-like Higgses up to a few hundred GeV masses are already excluded for a vast region of the model parameter space from the LHC searches, strikingly, there is a region of this parameter space that is beyond the reach of the existing LHC searches, and doubly/singly-charged and neutral Higgses as light as 200 GeV or even lighter are still allowed by the LHC data. We study several search strategies targeting different parts of this LHC elusive parameter space at two configurations of $e^-e^+$ colliders -- 500 GeV and 1 TeV centre of mass energies. We find that a vast region of this parameter space could be probed with 5$\sigma$ discovery with the early $e^-e^+$ colliders' data.