A study of inclusive production of open charm particles at HERA-B energies using &phis;(1020) as a tag

A study of inclusive charm production using the channel cc¯ → Di(D¯j) + X → &phis; + X' → K+K- has been done. Interaction triggered data from the HERA-B experiment with &phis;'s produced from pA interactions at s = 41.6 GeV are used for analysis. A detailed analysis of &phis; production at HERA-B energies has been done. The &phis; production cross-section has been measured to be s 0&phis; = ( 1.08+0.14-0.12 ) · Aalpha&phis; mb, where alpha&phis; is measured to be alpha&phis; = 0.92 +/- 0.03. The displacement of the decay vertex of the &phis;'s produced from charm decay compared to those produced directly in the primary interaction is used to obtain the fraction of &phis;'s from charm decay which in turn is used to determine the inclusive charm cross-section, namely, the sum of all charm cross-section, each weighted by its branching ratio to &phis;. The inclusive cross-section for open charm production has been measured in terms of the &phis; cross-section to be sumi BR( D → &phis;) s0Di = (11.12 +/- 5.90 +/- 4.80) · A 1.02 mub.