Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Measurement of the ttbar production cross section in the fully hadronic
  decay channel in pp collisions at 7 TeV   The first measurement of the top quark pair production cross section in the
fully hadronic channel at a center-of-mass energy of $\sqrt s = 7$ TeV is
presented. The measurement has been performed using an integrated luminosity of
1.09 fb$^{-1}$, collected with the CMS detector. The reconstruction of the
$t\bar t$ candidates is performed after a cut-based event selection using a
kinematic fit. A data-driven technique is used to estimate the dominant
background from QCD multijet production. The cross section is determined from a
fit to the top quark mass. The cross section measurement yields $\sigma(t\bar
t)=136 \pm 20 (stat.) \pm 40 (sys.) \pm 8 (lumi.)$ pb. This result is
consistent with an independent measurement in the same channel, with the
measurements in other decay channels and with the Standard Model predictions.

1
The categories of this paper are: cs
26
The categories of this paper are: bayes-an
27
The categories of this paper are: comp-gas
15
The categories of this paper are: nucl-ex
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The categories of this paper are: alg-geom
7
The categories of this paper are: hep-th
12
The categories of this paper are: nucl-th
25
The categories of this paper are: patt-sol
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The categories of this paper are: stat
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The categories of this paper are: quant-ph
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The categories of this paper are: math
5
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: acc-phys
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The categories of this paper are: econ
11
The categories of this paper are: hep-lat