Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Search for the Neutron Decay n$\rightarrow$ X+$\gamma$ where X is a dark
  matter particle   In a recent paper submitted to Physical Review Letters, Fornal and Grinstein
have suggested that the discrepancy between two different methods of neutron
lifetime measurements, the beam and bottle methods can be explained by a
previously unobserved dark matter decay mode, n$\rightarrow$ X+$\gamma$ where X
is a dark matter particle. We have performed a search for this decay mode over
the allowed range of energies of the monoenergetic gamma ray for X to be a dark
matter particle. We exclude the possibility of a sufficiently strong branch to
explain the lifetime discrepancy with greater than 4 sigma confidence.

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The categories of this paper are: plasm-ph
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The categories of this paper are: solv-int
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The categories of this paper are: ao-sci
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The categories of this paper are: stat
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The categories of this paper are: hep-ex
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The categories of this paper are: patt-sol
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The categories of this paper are: nlin
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The categories of this paper are: adap-org
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The categories of this paper are: dg-ga
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The categories of this paper are: bayes-an
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The categories of this paper are: funct-an
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The categories of this paper are: alg-geom
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The categories of this paper are: q-alg
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The categories of this paper are: eess
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The categories of this paper are: physics
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The categories of this paper are: quant-ph