Measurement of the product branching fraction B(c ->Theta X-c) x B(Theta(c)->Lambda X)

Based on a high statistics e+e-→cc̄ data sample, we report on the inclusive rate for charmed baryons to decay into Λ particles using charm-event tagging. We select e+e-→cc̄ events which have a clear anti-charm tag and measure the Λ content in the hemisphere opposite the tag (charge conjugate modes are implicit). This allows us to determine the product branching fraction BΛ=B(c→ΘcX)XB(Θ c→ΛX), where Θc represents a sum over all charmed baryons produced in e+e- fragmentation at √s=10.5 GeV, given our specific tags. We obtain BΛ=(1.87±0.03±0.33)%. ©2000 The American Physical Society.