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arXiv · hep-ph/0206189

Mass Effects in Hard Exclusive Photoproduction of $J/Ψ$ Mesons

B. Jaeger·W. Schweiger
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Abstract

We report on an attempt to describe hard exclusive photoproduction of $J/Ψ$ mesons, i.e. the reaction $γp \to J/Ψp$, by means of a modified version of the hard-scattering approach, in which the proton is treated as a quark-diquark rather than a three-quark system. In order to improve the applicability of the model at momentum transfers of only a few GeV we take into account constituent-mass effects in the calculation of the perturbative scattering amplitude. With a standard $J/Ψ$-meson distribution amplitude and diquark-model parameters adopted from preceding investigations of other photon-induced reactions our predictions for differential cross sections overestimate the naive extrapolation of the low-momentum transfer ZEUS data. Our results, however, reveal the importance of taking into account the charm-quark mass.

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B. Jaeger, W. Schweiger. 2002-06-20. Mass Effects in Hard Exclusive Photoproduction of $J/Ψ$ Mesons. https://doi.org/10.1016/s0375-9474(02)01217-4

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