Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Study of hard double-parton scattering in four-jet events in $pp$
  collisions at $\sqrt{s} = 7$ TeV with the ATLAS experiment   Inclusive four-jet events produced in proton-proton collisions at a
centre-of-mass energy of $\sqrt{s} = 7$ TeV are analysed for the presence of
hard double-parton scattering using data corresponding to an integrated
luminosity of 37.3 pb$^{-1}$, collected with the ATLAS detector at the LHC. The
contribution of hard double-parton scattering to the production of four-jet
events is extracted using an artificial neural network, assuming that hard
double-parton scattering can be approximated by an uncorrelated overlaying of
dijet events. For events containing at least four jets with transverse momentum
$p_{\mathrm{T}} \geq 20$ GeV and pseudorapidity $\eta \leq 4.4$, and at least
one having $p_{\mathrm{T}} \geq 42.5$ GeV, the contribution of hard
double-parton scattering is estimated to be $f_{\mathrm{DPS}} = 0.092
^{+0.005}_{-0.011} (\mathrm{stat.}) ^{+0.033}_{-0.037} (\mathrm{syst.})$. After
combining this measurement with those of the inclusive dijet and four-jet
cross-sections in the appropriate phase space regions, the effective overlap
area between the interacting protons, $\sigma_{\mathrm{eff}}$, was determined
to be $\sigma_{\mathrm{eff}} = 14.9 ^{+1.2}_{-1.0} (\mathrm{stat.})
^{+5.1}_{-3.8} (\mathrm{syst.})$ mb. This result is consistent within the
quoted uncertainties with previous measurements of $\sigma_{\mathrm{eff}}$,
performed at centre-of-mass energies between 63 GeV and 8 TeV using various
final states, and it corresponds to $21^{+7}_{-6}$% of the total inelastic
cross-section measured at $\sqrt{s} = 7$ TeV. The distributions of the
observables sensitive to the contribution of hard double-parton scattering,
corrected for detector effects, are also provided.

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The categories of this paper are: math
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The categories of this paper are: cond-mat
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The categories of this paper are: physics
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The categories of this paper are: patt-sol
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The categories of this paper are: econ
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The categories of this paper are: q-fin
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The categories of this paper are: hep-th
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The categories of this paper are: hep-ph
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The categories of this paper are: adap-org
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The categories of this paper are: hep-lat
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The categories of this paper are: plasm-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: chao-dyn
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The categories of this paper are: funct-an
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The categories of this paper are: acc-phys
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The categories of this paper are: cs