Hidden-Sector Higgs Bosons at High-Energy Electron-Positron Colliders

TL;DR

This paper explores the potential to discover hidden-sector Higgs bosons at a 3 TeV electron-positron collider, focusing on regions where the LHC cannot detect such particles due to their heavy mass and weak couplings.

Contribution

It introduces the feasibility of detecting heavy, weakly coupled Higgs bosons at future electron-positron colliders, extending beyond LHC capabilities.

Findings

A 3 TeV collider can significantly improve discovery prospects for hidden-sector Higgs bosons.

Three search channels are identified as promising for detection.

Heavy Higgs states with masses over 1 TeV could be accessible at future colliders.

Abstract

The possibility of a scalar messenger that can couple the Standard Model (SM) to a hidden sector has been discussed in a variety of contexts in the literature in recent years. We consider the case that a new scalar singlet charged under an exotic spontaneously broken Abelian gauge symmetry mixes weakly with the SM Higgs resulting in two scalar mass states, one of which has heavily suppressed couplings to the SM particles. Previous phenomenological studies have focussed on potential signatures for such a model at the Large Hadron Collider (LHC). However, there are interesting regions of the parameter space in which the heavier Higgs state would be out of reach for LHC searches if its mass is greater than 1 TeV. We therefore investigate the discovery potential for such a particle at a 3 TeV electron-positron collider, which is motivated by the recent developments of the Compact Linear Collider (CLIC). We find that such an experiment could substantially extend our discovery reach for a heavy, weakly coupled Higgs boson, and we discuss three possible search channels.