| Abstract |
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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^- -> ccbar 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 = 0.574+-0.009 and a total rate of
N_{Lambda c}^{qqbar} = 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.
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