Semileptonic λc+ decays with the Mark II at PEP

Semileptonic λc+ decays have been observed in 29 GeV e+e- annihilation. We observe the channels λc+ → e+λX and λc+ → μ+λX. The production rate for λc+, times Br(λc → l+λX) of 0.0031 ± 0.0012 ± 0.0010 per hadronic event for electrons, and 0.0024 ± 0.0024 ± 0.0007 per hadronic event for muons. When combined with the Lund model prediction for λc+ production, this gives semileptonic branching ratios of roughly 5%, about what is expected. When combined with the UCLA model prediction for λc+ production, this gives semileptonic branching ratios of 17% and 13% for electrons and muons, somewhat higher than expected