Measurements of inelastic J / psi and psi-prime photoproduction at HERA
Collaboration
38 pages
Published in:
- Eur.Phys.J.C 27 (2003) 173-188
e-Print:
- hep-ex/0211011 [hep-ex]
Report number:
- DESY-02-163
Experiments:
View in:
Citations per year
Abstract:
The cross sections for inelastic photoproduction of J/psi and psi' mesons have been measured in ep collisions with the ZEUS detector at HERA, using an integrated luminosity of 38.0 pb-1. The events were required to have 0.1 < z < 0.9 and 50 < W < 180 GeV, where z is the fraction of the incident photon energy carried by the J/psi in the proton rest frame and W is the photon-proton centre-of-mass energy. The psi' to J/psi cross-section ratio was measured in the range 0.55 < z < 0.9. The J/psi data, for various ranges of transverse momentum, are compared to theoretical models incorporating colour-singlet and colour-octet matrix elements. Predictions of a next-to-leading-order colour-singlet model give a good description of the data, although there is a large normalisation uncertainty. The J/psi helicity distribution for z > 0.4 is compared to leading-order QCD predictions.Note:
- 31 pages, 10 figures
- positron p: colliding beams
- positron p: inelastic scattering
- J/psi(3100): photoproduction
- psi(3685): photoproduction
- psi mesons: leptonic decay
- channel cross section: ratio
- angular distribution
- transverse momentum dependence
- energy dependence
- photon: resolved
References(43)
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