J/ψ production in pp̅ collisions at √s = 1.8 TeV

Abstract

We have studied J/ψ production in pp̅ collisions at √s = 1.8 TeV with the D∅ detector at Fermilab using μ ⁺μ ^- data. We have measured the inclusive J/ψ production cross section as a function of J/ψ transverse momentum, p_T. For the kinematic range p_T > 8 GeV/c and |η| < 0.6 we obtain σ(pp̅ → J/ψ +X). Br(J/ψ → µ⁺µ^-)= 2.08 ± 0.17(stat) ± 0.46(syst) nb. Using the muon impact parameter we have estimated the fraction of J/ψ 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/ψ events has been measured to be fnonisol = 0.64 ± 0.08(stat)±0.06(syst). We have also obtained the fraction of J/ψ events resulting from radiative decays of Χ_c states, f_Χ = 0.32 ±0.07(stat)±0.07(syst). We discuss the implications of our measurements for charmonium production processes.