Search for doubly charged Higgs scalars inZdecay

We describe a search for the decay of the Z boson into pairs of doubly charged Higgs bosons with the Mark II detector operating at the SLAC Linear Collider. Each Higgs boson is assumed to decay into a same-sign leptonic pair. No event candidates are found in a sample of 528 Z decays. At the 95% confidence level, this result excludes the region of leptonic coupling ${\mathit{g}}_{\mathit{l}\mathit{l}}$>3×${10}^{\mathrm{-}7}$ and Higgs-boson mass 6.5<${\mathit{M}}_{\mathit{H}}$<36.5 GeV/${\mathit{c}}^2$ for isotriplet (left-handed) Higgs bosons. Isosinglet (right-handed) Higgs bosons are excluded in the same ${\mathit{g}}_{\mathit{l}\mathit{l}}$ interval and in the mass interval 7.3<${\mathit{M}}_{\mathit{H}}$<34.3 GeV/${\mathit{c}}^2$.