Triplet Higgs bosons at $e^{+}{e}^{-}$ colliders

We investigate the possibility of probing the triplet Higgs boson sector via single charged Higgs production in the process $e^{+}{e}^{-}\to H^{+}l{\nu }_l$, at high energy electron-positron colliders, using the tree level $H^{+}{W}^{-}Z$ coupling which is a unique feature of such models. We find that even LEP-200 can give nontrivial information upto $M_{H^{\pm }}\simeq 120$ GeV if the doublet -triplet mixing is not restricted by the current value of the $\rho$ parameter which is the case in models with a custodial symmetry. Further we point out that in such models, the 4-body, tree level decay $H^+ \to W^Z^ \to 4$ fermions dominates and hence provides a very clean signal when the four fermions are leptons. At NLC the discovery range for the charged Higgs in triplet models via this process is $\sim 400$ GeV.