Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quark and gluon form factors to four loop order in QCD: the $N_f^3$
  contributions   We calculate the four-loop massless QCD corrections with three closed quark
lines to quark and gluon form factors. We apply a novel integration by parts
algorithm based on modular arithmetic and compute all relevant master integrals
for arbitrary values of the space-time dimension. This is the first calculation
of a gluon form factor at this perturbative order in QCD.

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The categories of this paper are: physics
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The categories of this paper are: acc-phys
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The categories of this paper are: comp-gas
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The categories of this paper are: ao-sci
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The categories of this paper are: cs
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The categories of this paper are: bayes-an
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The categories of this paper are: stat
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The categories of this paper are: math-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: solv-int
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The categories of this paper are: chao-dyn
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The categories of this paper are: nucl-ex
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The categories of this paper are: cmp-lg
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The categories of this paper are: funct-an
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The categories of this paper are: q-bio
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The categories of this paper are: adap-org