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Search for the production of dark matter in association with top-quark pairs in the single-lepton final state in proton-proton collisions at sqrt(s) = 8 TeV

The CMS collaboration
JHEP 1506 (2015) 121, 2015

Abstract (data abstract)
A search is presented for particle dark matter produced in association with a pair of top quarks in pp collisions at a centre-of-mass energy of $\sqrt(s)$ = 8 TeV. The data were collected with the CMS detector at the LHC and correspond to an integrated luminosity of 19.7 fb$^{-1}$. This search requires the presence of one lepton, multiple jets, and large missing transverse energy. No excess of events is found above the SM expectation, and upper limits are derived on the production cross section. Interpreting the findings in the context of a scalar contact interaction between fermionic dark matter particles and top quarks, lower limits on the interaction scale are set. These limits are also interpreted in terms of the dark matter-nucleon scattering cross sections for the spin-independent scalar operator and they complement direct searches for dark matter particles in the low mass region. The signal region is defined as: - 1 lepton + >= 3 jets + >= 1 b-tagged jet - ptLepton > 30 GeV - |etaElectron| < 2.5, |etaMuon| < 2.1 - ptJet > 30 GeV - |etaJet| < 4.0 - $\mathrm{E_{T}^{miss}}$ > 320 GeV - min $\mathrm{\Delta\phi(j_{1,2},\vec{p}_{t}^{miss})}$ > 1.2 - $\mathrm{M_{T2}^{W}}$ > 200 GeV - $\mathrm{M_{T}}$ > 160 GeV.

  • Table 1

    Data from Table 1


    Systematic uncertainties from various sources and their impact on the total background prediction.

  • Table 2

    Data from Table 2


    Expected number of background events in the SR, expected number of signal events for a DM particle with the mass...

  • Table 3

    Data from Table 3


    Expected number of signal events in SR assuming an interaction scale $M_{*}$ = 100 GeV, signal efficiencies, and observed and...

  • Table 4

    Data from Figure 6


    Observed exclusion limits in the plane of DM particle mass and interaction scale, with the region below the solid curve...

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