Search for the single production of doubly-charged higgs bosons at OPAL

A searc h for the single pro duction of doubly-c harged Higgs bosons H deca ying into two like-signed leptons is performed using 600.7 pb-1 of e+e- collision data collected by the OP AL exp erimen t at LEP at cen tre-of-mass energies between 189 GeV and 209 GeV. Doubly-c harged Higgs bosons arise in Higgs triplet mo dels, whic h implemen t extensions in the Standard Mo del (SM) Higgs sector. Under certain circumstances the H could be also the ligh test Higgs boson and it should be accessible for LEP energies. No evidence for the existence of H is observ ed. Upp er limits are deriv ed on h ee , the Yukawa coupling of the H to like-signed electron pairs. A 95% con dence lev el upp er limit of h ee < 0.071 is inferred for M (H ) < 160 GeV assuming that the sum of the branc hing fractions of the H to all lepton avour com binations is 100%.