Charm production in fixed target experiments

Prompt lepton production in proton beam dump experiments has been critically analysed within the general frame work of Λsub(c)anti D and Danti D production and their subsequent semileptonic decays. Realistic decay modes based on recent experiments are used. We have investigated the effect of using different x dependences for the charm particles obtained either from simple quark counting rules or as inferred from strange particle production data. The Danti D production is assumed to have a linear A dependence and for the Λsub(c)anti D process both A1 and Asup(2/3) dependence is used. We show that by a simultaneous fit to the energy and angular distributions of prompt leptons in all the experiments the ratio of Λsub(c)anti D to Danti D production cross section can be determined. A comparison of this fit with these experimental distributions indicates that the x dependences based on strange particle data are strongly favoured. An Asup(2/3) dependence for Λsub(c)anti D production, which corresponds to a quasi-diffractive process, is favoured although within existing errors A1 dependence cannot be ruled out. Putting together the cross section results from our analysis with other results at similar energies (psub(1ab)proportional400 GeV/c) the production cross sections (Λsub(c)anti D) and (Danti D) are estimated to be proportional25 and proportional20 μb/nucleon respectively leading to a total inclusive charm cross section of proportional90 μb/nucleon. (orig.)