Measurement of elastic J/{Psi} photoproduction at HERA.
We present a measurement of the inelastic, non diffractive J/y photoproduction cross section in the reaction e+ p {yields} e+ J/yX with the ZEUS detector at HERA. The J/y was identified using both the m+m- and e+e- decay channels and events were selected within the range 0.4 < z < 0.9 (0.5 < z < 0.9) for the muon (electron) decay mode, where z is the fraction of the photon energy carried by the J/y in the proton rest frame. The cross section, the p2T and the z distributions, after having subtracted the contributions from resolved photon and diffractive proton dissociative processes, are given for the photon-proton centre of mass energy range 50 < W < 180 GeV; p2T is the square of the J/y transverse momentum with respect to the incoming proton beam direction. In the kinematic range 0.4 < z < 0.9 and p2T > 1 GeV2, NLO calculations of the photon-gluon fusion process based on the colour-singlet model are in good agreement with the data. The predictions of a specific leading order colour-octet model, as formulated to describe the CDF data on J/y hadroproduction, are not consistent with the data.
- Research Organization:
- Argonne National Laboratory (ANL)
- DOE Contract Number:
- AC02-06CH11357
- OSTI ID:
- 938397
- Report Number(s):
- ANL-HEP-PR-98-63
- Journal Information:
- Z. Phys. C, Journal Name: Z. Phys. C Journal Issue: 1997 Vol. 76; ISSN 0170-9739; ISSN ZPCFD2
- Country of Publication:
- United States
- Language:
- ENGLISH
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