Searching for the $W \gamma$ decay of a charged Higgs boson

TL;DR

This paper evaluates the potential for discovering a fermiophobic charged Higgs boson decaying into W gamma at the LHC, highlighting its sensitivity for masses below 200 GeV using specific kinematic observables.

Contribution

It introduces a detailed analysis of the W gamma decay channel for charged Higgs bosons, including simulation tools and sensitivity projections for future collider runs.

Findings

LHC can exclude charged Higgs masses below 130 GeV with 300 fb$^{-1}$ data.

Sensitivity extends up to 200 GeV for small triplet VEVs.

Simulation tools for this analysis are publicly available.

Abstract

We study the prospects for charged Higgs boson searches in the $W \gamma$ decay channel. This loop-induced decay channel can be important if the charged Higgs is fermiophobic, particularly when its mass is below the $WZ$ threshold. We identify useful kinematic observables and evaluate the future Large Hadron Collider sensitivity to this channel using the custodial-fiveplet charged Higgs in the Georgi-Machacek model as a fermiophobic benchmark. We show that the LHC with 300~fb$^{-1}$ of data at 14~TeV will be able to exclude charged Higgs masses below about 130~GeV for almost any value of the SU(2)$_L$-triplet vacuum expectation value in the model, and masses up to 200~GeV and beyond when the triplet vacuum expectation value is very small. We describe the signal simulation tools created for this analysis, which have been made publicly available.