Study of the decay ≃c+ → Λl+υl

Using the CLEO II detector at CESR we observe 500 Λl + pairs consistent with the semileptonic decay Λ c + → Λl + ν l . We measure σ (e + e − → Λ c + X).B (Λ c + → Λl + ν l ) = 4.77 ± 0.25 ± 0.66 pb. Combining with the charm semileptonic width and the lifetime of the Λ c we also obtain B (Λ c + → pK − π + ). We find no evidence for Λl + ν l final states in which there are additional Λ c + decay products. We measure the decay asymmetry parameter of Λ c + → Λe + ν e to be α Λc = − 0.89 −0.11 +0.17 −0.05 +0.09