Search for Doubly-Charged Higgs Boson Production at HERA

TL;DR

This paper reports a search for doubly-charged Higgs bosons in ep collisions at HERA, setting mass limits based on the absence of observed signals in high-mass same-charge lepton pairs.

Contribution

It provides the first limits on doubly-charged Higgs production at HERA, constraining their masses and Yukawa couplings using electron-proton collision data.

Findings

No evidence for doubly-charged Higgs production was observed.

Lower mass limits of 141 GeV and 112 GeV were set for specific decay channels.

Constraints on Yukawa couplings were derived from the data.

Abstract

A search for the single production of doubly-charged Higgs bosons H^{\pm \pm} in ep collisions is presented. The signal is searched for via the Higgs decays into a high mass pair of same charge leptons, one of them being an electron. The analysis uses up to 118 pb^{-1} of ep data collected by the H1 experiment at HERA. No evidence for doubly-charged Higgs production is observed and mass dependent upper limits are derived on the Yukawa couplings h_{el} of the Higgs boson to an electron-lepton pair. Assuming that the doubly-charged Higgs only decays into an electron and a muon via a coupling of electromagnetic strength h_{e \mu} = \sqrt{4 \pi \alpha_{em}} = 0.3, a lower limit of 141 GeV on the H^{\pm\pm} mass is obtained at the 95% confidence level. For a doubly-charged Higgs decaying only into an electron and a tau and a coupling h_{e\tau} = 0.3, masses below 112 GeV are ruled out.