J/Psi production in p(p)over-bar collisions at root s=1.8 TeV

We have studied J/psi production in p (p) over bar collisions at root s = 1.8 TeV with the DO detector at Fermilab using mu(+)mu(-) data. We have measured the inclusive J/psi production cross section as a function of J/psi transverse momentum, p(T). For the kinematic range p(T) > 8 GeV/c and \eta\ < 0.6 we obtain sigma(p (p) over bar --> J/psi + X) . Br(J/psi --> mu(+)mu(-)) = 2.08 +/- 0.17(stat) +/- 0.46(syst) nb. Using the muon impact parameter we have estimated the fraction of J/psi mesons coming from B meson decays to be f(b) = 0.35 +/- 0.09(stat) +/- 0.10(syst) and inferred the inclusive b production cross section. From the information on the event topology the fraction of nonisolated J/psi events has been measured to be f(nonisol) = 0.64 +/- 0.08(stat) +/- 0.06(syst). We have also obtained the fraction of J/psi events resulting from radiative decays of chi(c) states, f(chi) = 0.32 +/- 0.07(stat) +/- 0.07(syst). We discuss the implications of our measurements for charmonium production processes.