Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Chiral-Symmetry and Strange Four-Quark Matrix Elements   We consider the matrix elements of the left-handed flavor-conserving
four-quark operators in the nucleon and pion states. Using chiral symmetry, we
derive relationships among these matrix elements. We argue that the $\Delta I =
1/2$ rule of hyperon and kaon non-leptonic weak decay implies possible large
strange-quark content in the nucleon and pion.

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The categories of this paper are: dg-ga
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The categories of this paper are: eess
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The categories of this paper are: cond-mat
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The categories of this paper are: q-alg
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The categories of this paper are: alg-geom
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
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The categories of this paper are: q-fin
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The categories of this paper are: ao-sci
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The categories of this paper are: supr-con
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The categories of this paper are: mtrl-th
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-lat
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The categories of this paper are: q-bio
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The categories of this paper are: hep-th
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The categories of this paper are: chao-dyn