Charm and beauty production in experiment WA92

Using a sample of $1.4⋅108$ triggered events, produced in π-Cu and π-W interactions at $350 GeV/c,$ we have studied charm and beauty production. $J/ψ$ and $ψ′$ mesons are identified through their decays into muon pairs and are selected in the Feynman-x range $xF>0.$ Inclusive $J/ψ$ and $ψ′$ cross-sections and $J/ψ$ differential cross-sections as functions of $xF$ and $pT$ are measured. A fit to the data for different targets gives $α(J/ψ){Si,Cu,W}=0.87±0.05 (stat.)±0.04 (syst.),$ $σ0(J/ψ)=(216.2±5.4 (stat.)±13.3 (syst.)) nb/nucleon$ and $σ0(ψ′)=(28.3±8.1(stat.)±11.3 (syst.)) nb/nucleon.$ For the study of beauty production, we have identified 26 beauty events. The estimated background in this sample is $0.6±0.6$ events. From these data, assuming a linear A-dependence, we measure a beauty production cross-section integrated over all $xF$ of $5.7−1.1+1.3 (stat.)−0.5+0.6(syst.) nb/N.$ Differential distributions with respect to $xF$ and $pT2$ have been determined as well as some two-particle kinematic variables. Our results are compared with previous experiments and with a next-to-leading-order QCD calculation.