Photoproduction asymmetries of the charm baryons Λc, Σc++ and Σc0 at the Fermilab experiment E831/focus

Full text follows: In photon-hadron collisions, it is expected that charm quarks are produced by the photon-gluon process. This process at leading order (LO) in perturbative quantum chromo-dynamics (QCD) predicts symmetric distributions for charm/anticharm quark production. Asymmetries introduced by next to leading order (NLO) calculations are expected to be negligibly small. However, when the charm/articharm quarks hadronize, non perturbative effects in the recombination process may induce an asymmetry between charm and anticharm final states. The measurement of photoproduction asymmetries could provide valuable information on the hadronization process, which is one of the least understood phenomena in QCD. We present a study on the charm-anticharm photoproduction asymmetry using Λc+/Λc-, Σc++/Σc-- and Σc0/Σ-barc0 baryon candidates. Data used is from the E831/FOCUS experiment, collected during 1996-1997 Fermilab fixed target run. The asymmetry is studied in intervals of pT2, pL, and xF for the case of Λc baryons, while global values are extracted for the Σc baryons, due to the lack of statistics. (author)