Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Long-distance contribution to the forward-backward asymmetry in decays
  K+ --> pi+ l+ l-   The long-distance contribution via the two-photon intermediate state to the
forward-backward asymmetries in decays K+ --> pi+ l+ l- (l=e and mu) has been
studied within the standard model. In order to evaluate the dispersive part of
the K+ --> pi+ gamma* gamma* --> pi+ l+ l- amplitude, we employ a
phenomenological form factor to soften the ultraviolet behavior of the
transition. It is found that, this long-distance transition, although subject
to some theoretical uncertainties, can lead to significant contributions to the
forward-backward asymmetries, which could be tested in the future high-precise
experiments.

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The categories of this paper are: cond-mat
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The categories of this paper are: hep-th
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The categories of this paper are: hep-lat
29
The categories of this paper are: funct-an
19
The categories of this paper are: eess
20
The categories of this paper are: acc-phys
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The categories of this paper are: quant-ph
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The categories of this paper are: cs
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The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
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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: adap-org
37
The categories of this paper are: supr-con
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The categories of this paper are: cmp-lg
22
The categories of this paper are: chao-dyn