Using the CLEO II detector at CESR we observe 500 Λl+ pairs consistent with the semileptonic decay Λc+ → λ+ν We measure σ(e+e- → Λ+cX) · B(Λ+c → Λl+νl) = 4.77±0.25±0.66 pb. Combining with the charm semileptonic width and the lifetime of the Λc we also obtain B(Λ+c → pK-π+). We find no evidence for Λl+νl final states in which there are additional Λ+c decay products. We measure the decay asymmetry parameter of Λ+c → Λe+νe to be αΛc = -0.89+0.17+0.09-0.11-0.05.
ASJC Scopus subject areas
- Nuclear and High Energy Physics