Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Watson's theorem and electromagnetism in K -> pi pi decay   We consider what constraints unitarity and CPT invariance yield on the strong
and electromagnetic phases entering K -> pi pi decay. In particular, we show
that the relative size of the electromagnetically-induced changes in the I=0
and I=2 phase shifts in the two--pion final state do not depend on the explicit
coupling to the pi^+ pi^- gamma channel. This demonstrates that Watson's
theorem can be extended to include the presence of electromagnetism. We point
out the consequences for the general structure of the K -> pi pi decay
amplitudes in the presence of isospin violation.

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The categories of this paper are: hep-lat
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The categories of this paper are: cs
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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: nucl-ex
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The categories of this paper are: chem-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: plasm-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: acc-phys
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The categories of this paper are: bayes-an
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The categories of this paper are: nlin
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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-fin
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The categories of this paper are: dg-ga