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ISSN - 15507998, Physical Review D - Particles, Fields, Gravitation and Cosmology, 2007, vol. 75, p. -

Inclusive Λc+ production in e+e- annihilations at s=10.54GeV and in Υ(4S) decays

Aubert B., Bona M., Boutigny D., Couderc F., Karyotakis Y., Lees J. P., Poireau V., Tisserand V., Zghiche A., Grauges E., Palano A., Chen J. C., Qi N. D., Rong G., Wang P., Zhu Y. S., Eigen G., Ofte I., Stugu B., Abrams G. S., Battaglia M., Brown D. N., Button-Shafer J., Cahn R. N., Charles E., Gill M. S., Groysman Y., Jacobsen R. G., Kadyk J. A., Kerth L. T., Kolomensky Yu G., Kukartsev G., Lynch G., Mir L. M., Orimoto T. J., Pripstein M., Roe N. A., Ronan M. T., Wenzel W. A., Sanchez P. Del Amo, Barrett M., Ford K. E., Harrison T. J., Hart A. J., Hawkes C. M., Watson A. T., Held T., Koch H., Lewandowski B., Pelizaeus M., Peters K., Schroeder T., Steinke M., Boyd J. T., Burke J. P., Cottingham W. N., Walker D., Asgeirsson D. J., Cuhadar-Donszelmann T., Fulsom B. G., Hearty C., Knecht N. S., Mattison T. S., McKenna J. A., Khan A., Kyberd P., Saleem M., Sherwood D. J., Teodorescu L., Blinov V. E., Bukin A. D., Druzhinin V. P., Golubev V. B., Onuchin A. P., Serednyakov S. I., Skovpen Yu I., Solodov E. P., Todyshev Ku Y., Bondioli M., Bruinsma M., Chao M., Curry S., Eschrich I., Kirkby D., Lankford A. J., Lund P., Mandelkern M., Mommsen R. K., Roethel W., Stoker D. P., Abachi S., Buchanan C., Foulkes S. D., Gary J. W., Long O., Shen B. C., Wang K., Zhang L., Hadavand H. K., Hill E. J.

We present measurements of the total production rates and momentum distributions of the charmed baryon Λc+ in e+e-→hadrons at a center-of-mass energy of 10.54 GeV and in Υ(4S) decays. In hadronic events at 10.54 GeV, charmed hadrons are almost exclusively leading particles in e+e-→cc̄ events, allowing direct studies of c-quark fragmentation. We measure a momentum distribution for Λc+ 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 xp=0.574±0.009 and a total rate of NΛcqq̄=0.057±0.002(exp.)±0.015(BF)Λc+ per hadronic event, where the experimental error is much smaller than that due to the branching fraction into the reconstructed decay mode, pK-π+. In Υ(4S) decays we measure a total rate of NΛcΥ=0.091±0. 006(exp.)±0.024(BF) per Υ(4S) decay, and find a much softer momentum distribution than expected from B decays into a Λc+ plus an antinucleon and one to three pions. © 2007 The American Physical Society.