Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Search for fractionally charged particles in pp collisions at sqrt(s) =
  7 TeV   A search is presented for free heavy long-lived fractionally charged
particles produced in pp collisions at sqrt(s) = 7 TeV. The data sample was
recorded by the CMS detector at the LHC and corresponds to an integrated
luminosity of 5.0 inverse femtobarns. Candidate fractionally charged particles
are identified by selecting tracks with associated low charge measurements in
the silicon tracking detector. Observations are found to be consistent with
expectations for background processes. The results of the search are used to
set upper limits on the cross section for pair production of fractionally
charged, massive spin-1/2 particles that are neutral under SU(3)[C] and
SU(2)[L]. We exclude at 95% confidence level such particles with electric
charge +/-2e/3 with masses below 310 GeV, and those with charge +/-e/3 with
masses below 140 GeV.

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The categories of this paper are: eess
29
The categories of this paper are: funct-an
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The categories of this paper are: supr-con
35
The categories of this paper are: mtrl-th
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The categories of this paper are: hep-ph
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The categories of this paper are: q-fin
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The categories of this paper are: hep-lat
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The categories of this paper are: econ
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The categories of this paper are: q-alg
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The categories of this paper are: gr-qc
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The categories of this paper are: nlin
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The categories of this paper are: solv-int
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The categories of this paper are: nucl-th
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The categories of this paper are: bayes-an
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The categories of this paper are: acc-phys
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The categories of this paper are: q-bio