Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Hard exclusive electroproduction of a pion in the backward region   We study the scaling regime of pion electroproduction in the backward region,
eN->e'N'pi. We compute the leading-twist amplitude in the kinematical region,
where it factorises into a short-distance matrix element and long-distance
dominated nucleon Distribution Amplitudes and nucleon to pion Transition
Distribution Amplitudes. Using the chiral limit of the latter, we obtain a
first estimate of the cross section, which may be experimentally studied at
JLab or Hermes.

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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: astro-ph
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The categories of this paper are: hep-th
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The categories of this paper are: acc-phys
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The categories of this paper are: hep-ex
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The categories of this paper are: dg-ga
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The categories of this paper are: mtrl-th
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The categories of this paper are: funct-an
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The categories of this paper are: gr-qc
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The categories of this paper are: nlin
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The categories of this paper are: adap-org
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The categories of this paper are: plasm-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: atom-ph
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The categories of this paper are: q-alg