Aubert, B (reprint author), CNRS, IN2P3, Phys Particules Lab, F-74941 Annecy Le Vieux, France.
We present measurements of the total production rates and momentum distributions of the charmed baryon Lambda(+)(c) in e(+)e(-)-> hadrons at a center-of-mass energy of 10.54 GeV and in Upsilon(4S) decays. In hadronic events at 10.54 GeV, charmed hadrons are almost exclusively leading particles in e(+)e(-)-> cc events, allowing direct studies of c-quark fragmentation. We measure a momentum distribution for Lambda(+)(c) baryons that differs significantly from those measured previously for charmed mesons. Comparing with a number of models, we find none that can describe the distribution completely. We measure an average scaled momentum of < x(p)>=0.574 +/- 0.009 and a total rate of N-Lambda c(qq)=0.057 +/- 0.002(exp.)+/- 0.015(BF) Lambda(+)(c) per hadronic event, where the experimental error is much smaller than that due to the branching fraction into the reconstructed decay mode, pK(-)pi(+). In Upsilon(4S) decays we measure a total rate of N-Lambda c(Upsilon)=0.091 +/- 0.006(exp.)+/- 0.024(BF) per Upsilon(4S) decay, and find a much softer momentum distribution than expected from B decays into a Lambda(+)(c) plus an antinucleon and one to three pions.