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Charmonium photoproduction

A. Sibirtsev·S. Krewald·A. W. Thomas
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Abstract

The available data on $J/Ψ$ photoproduction are analyzed in terms of pomeron exchange, two gluon exchange and photon-gluon fusion models. Allowing the pomeron-quark interaction to be flavour dependent and introducing the soft and hard pomerons it is possible to reproduce the data at $\sqrt{s}{>}$10 GeV and small $|t|$. The two gluon exchange calculations indicate strong sensitivity to the gluon distribution function. The results obtained with the most modern MRST2001 and DL PDF reproduce the forward $J/Ψ$ photoproduction cross section at $\sqrt{s}{>}$10 GeV. The calculations with the photon-gluon fusion model and with MRST2001 and DL PDF are also in reasonable agreement with the data on the total $J/Ψ$ photoproduction cross section. We allocate the $J/Ψ$ photoproduction at low energies and large $|t|$ to the mechanism different from pomeron or two gluon exchanges. We consider that this might be axial vector trajectory exchange that couples to the axial form factor of the nucleon.

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A. Sibirtsev, S. Krewald, A. W. Thomas. 2003-01-27. Charmonium photoproduction. https://arxiv.org/abs/nucl-th/0301082

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