Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Small-x physics and heavy quark photoproduction in the semihard approach
  at HERA   Processes of hevy quark photoproduction at HERA energies and beyond are
investigated using the semihard ($k_{\bot}$ factorization) approach. The
virtuality and longitudinal polarization of gluons in the photon - gluon
subprocess as well as the saturation effects in the gluon distribution function
at small $x$ have been taken into account. The total cross sections, rapidity
and $p_{\bot}$ distributions of the charm and beauty quark photoproduction have
been calculated. We obtained the some differences between the predictions of
the standard parton model and the semihard approach used here.

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The categories of this paper are: astro-ph
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The categories of this paper are: hep-th
16
The categories of this paper are: stat
4
The categories of this paper are: cond-mat
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The categories of this paper are: nucl-th
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The categories of this paper are: bayes-an
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The categories of this paper are: physics
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The categories of this paper are: q-bio
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The categories of this paper are: hep-lat
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The categories of this paper are: q-fin
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The categories of this paper are: nlin
25
The categories of this paper are: patt-sol
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The categories of this paper are: supr-con
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The categories of this paper are: atom-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: alg-geom