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.

Measurements of inelastic J/psi and psi ' photoproduction at HERA / S., C., D., K., S., M., B., M., J., R., R., Y., M. C., K., P., A., G., B., M., B., L., B., D., B., A., B., G., B., G. C., R., L., C., F., C., A., C., M., C., S. D., P., et al.. - In: THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS. - ISSN 1434-6044. - 27:(2003), pp. 173-188. [10.1140/epjc/s2002-01130-2]

Measurements of inelastic J/psi and psi ' photoproduction at HERA

D'AGOSTINI, Giulio;NIGRO, Andrea;
2003

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.
2003
01 Pubblicazione su rivista::01a Articolo in rivista
Measurements of inelastic J/psi and psi ' photoproduction at HERA / S., C., D., K., S., M., B., M., J., R., R., Y., M. C., K., P., A., G., B., M., B., L., B., D., B., A., B., G., B., G. C., R., L., C., F., C., A., C., M., C., S. D., P., et al.. - In: THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS. - ISSN 1434-6044. - 27:(2003), pp. 173-188. [10.1140/epjc/s2002-01130-2]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/394025
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