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Inelastic Photoproduction of J/psi Mesons at HERA |
| Reference |
N.N., to be presented at DIS 2002, Spring 2002 |
| Figures |
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| Contact |
B.Naroska |
| Abstract |
An analysis of inelastic photoproduction of J/psi mesons is presented using data collected at the ep collider HERA corresponding to an integrated luminosity of about 80 pb^-1. Differential and double differential cross sections are measured in a wide kinematical region (60 < W_(gamma p) < 260 GeV, 1 < p_t^2 < 60 GeV^-2 and 0.05 < z < 0.9) where z is the J/psi energy relative to the photon energy. Cross sections at z < 0.3 are presented for the first time. Recent theoretical calculations within the Colour Singlet Model at NLO for direct photon processes give a good description of the data in the medium z region (0.3 < z < 0.9) up to the highest p_t^2 values. A calculation using a kt factorisation approach in LO is also able to describe these data. The data are also compared to LO calculations within a non-relativistic QCD framework including colour octet and colour singlet contributions for direct and resolved photons in the whole z range. Considerable progress has been made in the understanding of the data within such a framework. The polarisation of the J/psi meson is measured as a function of z and p_t. |
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