Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Search for the K_S -> e+e- decay with the KLOE detector   We present the result of a direct search for the decay K_S -> e+e-, obtained
with a sample of e+e- -> phi -> K_S K_L events produced at DAFNE, the Frascati
phi-factory, for an integrated luminosity of 1.9 fb^-1. The search has been
performed using a pure K_S beam tagged by the simultaneous detection of a K_L
interaction in the calorimeter. Background rejection has been optimized by
using both kinematic and particle identification cuts. We find BR(K_S -> e+e-)
< 9x10^-9 at 90% CL, which improves by an order of magnitude on the previous
best limit.

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The categories of this paper are: q-alg
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The categories of this paper are: adap-org
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The categories of this paper are: cmp-lg
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The categories of this paper are: patt-sol
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The categories of this paper are: cond-mat
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The categories of this paper are: stat
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The categories of this paper are: comp-gas
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The categories of this paper are: physics
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The categories of this paper are: astro-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: nlin
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The categories of this paper are: dg-ga
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The categories of this paper are: math
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-bio
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The categories of this paper are: acc-phys