Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Comment on "Subleading Corrections to Parity Violating Pion
  Photoproduction"   In a recent preprint, hep-ph/0012253, Zhu et al. calculated a part of the
next-to-leading order corrections to parity-violating pion photoproduction
(pol)gamma p-> pi^+ n in heavy-baryon chiral perturbation theory. They claim
they have found the contribution as large as the leading-order. If correct, the
process will not be a clean way to extract the longest range PV pion-nucleon
coupling constant h_{\pi NN}^(1), as was asserted in our previous publications
(hep-ph/0011230, nucl-th/0011100). In this comment we show that there is no
solid evidence to support Zhu et al.'s claim. Moreover, we show that the
subleading parity-violating coupling h_V cannot be extracted from observables
at the order of interest based on the formalism of effective field theory.

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The categories of this paper are: cs
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The categories of this paper are: ao-sci
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The categories of this paper are: math
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The categories of this paper are: nlin
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-lat
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The categories of this paper are: mtrl-th
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The categories of this paper are: math-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-th
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The categories of this paper are: physics
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The categories of this paper are: dg-ga
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The categories of this paper are: bayes-an
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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: atom-ph