Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Introduction to Perturbative QCD   This is a written version of two lectures given at the First School on Field
Theory and Gravitation in Vitoria (Brasil) April 15-19, 1997. We discuss the
foundation of QCD as the theory of strong interactions and the perturbative
analysis of e^+e^- annihilation into hadrons. Typical concepts of perturbative
QCD studies, such as collinear singularities, jets, Sudakov form factors, are
explained working out this case.

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The categories of this paper are: funct-an
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The categories of this paper are: acc-phys
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The categories of this paper are: chao-dyn
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The categories of this paper are: bayes-an
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The categories of this paper are: dg-ga
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The categories of this paper are: stat
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The categories of this paper are: eess
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The categories of this paper are: astro-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: patt-sol
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The categories of this paper are: mtrl-th
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The categories of this paper are: quant-ph
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The categories of this paper are: math-ph
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The categories of this paper are: solv-int
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The categories of this paper are: q-bio
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The categories of this paper are: q-fin