Inclusive x, and b-quark Production in $p Collisions at 4s = 1.8 TeV

We report the full reconstruction of Xc-mesons through the decay chain xc -+ Jlh, Jltl, + p+p-, usmg data obtained at the Collider Detector at Fermilab in 2.6f0.2 pb-’ of Isp collisions at fi = 1.8 TeV. This exclusive xc sample, the fust observed at a hadron collider, is used to measure the xcmeson production cross section times branching fractions. We obtain cr. Br = 3.2zt0.4(stat)f:::(syst) nb for xc-mesons decaying to J/$ with pi > 6.0 GeV/c and pseudorapidity 171 < 0.5. Prom this and the inclusive J/$ cross section we calculate the inclusive bquark crow section to be 12.0 f 4.5 pb for p$ > 8.5 GeV/c and ]y*l < 1. PACS numbers: 13.85.Ni, 14.4O.Js, 14.80.Dq. This letter reports the first full reconstruction of Xc-mesons at a hadron collider, through the decay chain xc -+ J/$-y, J/$ + p+/r-. The observed x. sample is used to measure the xc production cross section times branching fractions for the unresolved xc angular momentum states. The results are based upon data from fi = 1.8 TeV fi collisions observed at the Collider Detector at Fermilab (CDF). Two mechanisms have been proposed for the production of charmonium states at Tevatron energies: direct charmonium production and the decay of b-flavored hadrons [l, 21. The latter mechanism is predicted to dominate production of hightransverse momentum (pr) J/$-mesons, with xc decays contributing more than 91% of the remaining “direct” J/tl, production rate. In contrast, X=meson production is expected to proceed largely through direct gluon fusion [2,3,4,5], and should dominate