Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Colour-octet Contributions to J/psi Hadroproduction at Fixed Target
  Energies   We investigate the integrated cross section for forward $\jpsi$ production in
proton-proton and pion-proton collisions at centre of mass energies upto 60
GeV. We find that colour-octet contributions to the cross section are crucially
important, and their inclusion produces a very good description of the data.
Since the values of non-perturbative matrix elements are fixed by other
experiments, these predictions are parameter-free.

31
The categories of this paper are: ao-sci
33
The categories of this paper are: plasm-ph
36
The categories of this paper are: cmp-lg
23
The categories of this paper are: solv-int
18
The categories of this paper are: econ
12
The categories of this paper are: nucl-th
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs
6
The categories of this paper are: astro-ph
4
The categories of this paper are: cond-mat
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The categories of this paper are: q-alg
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
2
The categories of this paper are: math
26
The categories of this paper are: bayes-an
13
The categories of this paper are: quant-ph