We have studied the production of J/ψ and ψ(2S) charmonium mesons in 515 GeV/c π−Be collisions in the Feynman-x range 0.1<xF<0.8. J/ψ mesons were detected via their decay into μ+μ−, and ψ(2S) mesons were studied in both the μ+μ− and J/ψπ+π− decay modes. J/ψ differential cross sections have been measured as functions of xF,pT2, and the cosine of the Gottfried-Jackson decay angle. We measure an inclusive J/ψ cross section of B(J/ψ→μ+μ−)σ(π−Be→J/ψ+X)/A= [9.3±0.1(stat)±1.1(syst)] nb/nucleon for J/ψ xF≳0.1. Our results are compared with those from other experiments performed at lower beam energies. We also measure the differential ψ(2S) cross section as a function of both xF and pT2, and a ψ(2S) inclusive cross section of B(ψ(2S)→J/ψπ+π−)σ(π−Be→ψ(2S)+X)/A=[7. 4±1.5(stat)±1.2(syst)] nb/nucleon for ψ(2S) xF≳0.1. The fraction of the inclusive J/ψ yield due to ψ(2S) meson decays is 0.083±0.017(stat) ±0.013(syst), and the observed ratio of ψ(2S) decay rates is B(ψ(2S)→J/ψπ+π−)/B(ψ(2S)→μ+μ−) =30.2±7.2(stat)±6.8(syst). We have searched for production of ‘‘hidden’’ charm resonances decaying into either J/ψπ±,ψ(2S)π±, or J/ψπ+π− systems, and report an upper limit of 3.1 nb/nucleon for the product of branching ratio and cross section for the recently reported enhancement at a J/ψπ+π− mass of 3.836 GeV/c2. © 1996 The American Physical Society.
None
We have measured the differential cross section for the inclusive production of psi(2S) mesons decaying to mu^{+} mu^{-1} that were produced in prompt or B-decay processes from ppbar collisions at 1.96 TeV. These measurements have been made using a data set from an integrated luminosity of 1.1 fb^{-1} collected by the CDF II detector at Fermilab. For events with transverse momentum p_{T} (psi(2S)) > 2 GeV/c and rapidity |y(psi(2S))| < 0.6 we measure the integrated inclusive cross section sigma(ppbar -> psi(2S)X) Br(psi(2S) -> mu^{+} mu^{-}) to be 3.29 +- 0.04(stat.) +- 0.32(syst.) nb.
We have studied J ψ production in p p collisions at s = 1.8 TeV with the DØ 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(p p → 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 f nonisol = 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.
Forum