Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the Casimir scaling violation in the cusp anomalous dimension at
  small angle   We compute the four-loop $n_f$ contribution proportional to the quartic
Casimir of the QCD cusp anomalous dimension as an expansion for small cusp
angle $\phi$. This piece is gauge invariant, violates Casimir scaling, and
first appears at four loops. It requires the evaluation of genuine non-planar
four-loop Feynman integrals. We present results up to ${\mathcal O}(\phi^4)$.
One motivation for our calculation is to probe a recent conjecture on the
all-order structure of the cusp anomalous dimension. As a byproduct we obtain
the four-loop HQET wave function anomalous dimension for this color structure.

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The categories of this paper are: cond-mat
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The categories of this paper are: chao-dyn
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The categories of this paper are: chem-ph
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The categories of this paper are: math-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: patt-sol
32
The categories of this paper are: atom-ph
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The categories of this paper are: astro-ph
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The categories of this paper are: stat
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The categories of this paper are: mtrl-th
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The categories of this paper are: econ
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The categories of this paper are: funct-an
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The categories of this paper are: ao-sci
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The categories of this paper are: acc-phys
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The categories of this paper are: physics
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The categories of this paper are: quant-ph