Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Charmonium photoproduction   The available data on $J/\Psi$ 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 $J/\Psi$ 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 $J/\Psi$ photoproduction cross section. We allocate the
$J/\Psi$ 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.

22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
30
The categories of this paper are: q-alg
4
The categories of this paper are: cond-mat
3
The categories of this paper are: physics
9
The categories of this paper are: nlin
8
The categories of this paper are: hep-ex
23
The categories of this paper are: solv-int
11
The categories of this paper are: hep-lat
32
The categories of this paper are: atom-ph
18
The categories of this paper are: econ
19
The categories of this paper are: eess
6
The categories of this paper are: astro-ph
13
The categories of this paper are: quant-ph
7
The categories of this paper are: hep-th
34
The categories of this paper are: chem-ph