Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Two--Loop Massive Operator Matrix Elements for Unpolarized Heavy Flavor
  Production to $O(\epsilon)   We calculate the $O(\alpha_s^2)$ massive operator matrix elements for the
twist--2 operators, which contribute to the heavy flavor Wilson coefficients in
unpolarized deeply inelastic scattering in the region $Q^2 \gg m^2$, up to the
$O(\epsilon)$ contributions. These terms contribute through the renormalization
of the $O(\alpha_s^3)$ heavy flavor Wilson coefficients of the structure
function $F_2(x,Q^2)$. The calculation has been performed using light--cone
expansion techniques without using the integration-by-parts method. We
represent the individual Feynman diagrams by generalized hypergeometric
structures, the $\epsilon$--expansion of which leads to infinite sums depending
on the Mellin variable $N$. These sums are finally expressed in terms of nested
harmonic sums using the general summation techniques implemented in the {\tt
Sigma} package.

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The categories of this paper are: gr-qc
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The categories of this paper are: funct-an
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The categories of this paper are: q-alg
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The categories of this paper are: ao-sci
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The categories of this paper are: mtrl-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: nlin
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The categories of this paper are: cmp-lg
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The categories of this paper are: cond-mat
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The categories of this paper are: stat
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The categories of this paper are: solv-int
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The categories of this paper are: physics
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The categories of this paper are: q-fin
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The categories of this paper are: comp-gas
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The categories of this paper are: chem-ph
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The categories of this paper are: atom-ph