Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Isospin Breaking in the Pion-Nucleon Coupling from QCD Sum Rules   We use QCD sum rules for the three point function of a pseudoscalar and two
nucleonic currents in order to estimate the charge dependence of the pion
nucleon coupling constant $g_{NN\pi}$ coming from isospin violation in the
strong interaction. The effect can be attributed primarily to the difference of
the quark condensates $<{\bar u}u>$ and $<{\bar d}d>$. For the splitting
$(g_{pp\pi_0} - g_{nn\pi_0}) / g_{NN\pi}$ we obtain an interval of $1.2 *
10^{-2}$ to $3.7 * 10^{-2}$, the uncertainties coming mainly from the input
parameters. The charged pion nucleon coupling is found to be the average of
$g_{pp\pi_0}$ and $g_{nn\pi_0}$. Electromagnetic effects are not included.

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The categories of this paper are: atom-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: quant-ph
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The categories of this paper are: econ
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The categories of this paper are: adap-org
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The categories of this paper are: q-alg
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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: cond-mat
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The categories of this paper are: physics
1
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: acc-phys
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The categories of this paper are: eess
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The categories of this paper are: math
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The categories of this paper are: nucl-ex