Search for the Single Production of Doubly-Charged Higgs Bosons and Constraints on their Couplings from Bhabha Scattering

TL;DR

This paper reports a search for doubly-charged Higgs bosons in electron-positron collisions, setting new upper limits on their couplings and providing the first constraints from Bhabha scattering at LEP.

Contribution

It presents the first combined search for single production of doubly-charged Higgs bosons and constraints from Bhabha scattering at LEP, with no evidence found.

Findings

No evidence for doubly-charged Higgs bosons was observed.

Upper limits on Yukawa couplings were established.

Constraints from Bhabha scattering were derived for masses below 2 TeV.

Abstract

A search for single production of doubly-charged Higgs bosons has been performed using 600.7 pb^-1 of e+e- collision data with sqrt(s)=189--209GeV collected by the OPAL detector at LEP. No evidence for the existence of H++/-- is observed. Upper limits on the Yukawa coupling of the H++/-- to like-signed electron pairs are derived. Additionally, indirect constraints on the Yukawa coupling from Bhabha scattering, where the H++/-- would contribute via t-channel exchange, are derived for M(H++/--) < 2TeV. These are the first results for both a single production search and constraints from Bhabha scattering reported from LEP.