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Search for dark matter in events with a Z boson and missing transverse momentum in pp collisions at $\sqrt{s}$=8 TeV with the ATLAS detector

The ATLAS collaboration
Phys.Rev. D90 (2014) 012004, 2014

Abstract (data abstract)
Search for production of dark matter particles recoiling against a leptonically decaying Z boson in 20.3 fb-1 of pp collisions at sqrt(s)=8 TeV with the ATLAS detector at the Large Hadron Collider. Events with large missing transverse momentum and two oppositely-charged electrons or muons consistent with the decay of a Z boson are analyzed. The fiducial region is defined as: - 2e+MET or 2mu+MET - ptLepton > 20 GeV - |etaLepton| < 2.5 - mll must be between 76 and 106 GeV - |phi_METZ|>2.5, where phi_METZ is the difference between the phi angles of the dilepton system and the MET. - |MET - pTZ| / pTZ < 0.5, where pTZ is the transverse momentum of the dilepton system. - |etaZ|<2.5, where etaZ is the pseudorapidity of the dilepton system. - No events with a jet for which ptJet > 25 GeV, |etaJet| < 2.5, and the jet is not within DeltaR<=0.2 of an electron. - No events with a third lepton for which ptLepton > 7 GeV - min(DeltaR(l,l)) > 0.2 - Four signal regions defined by their MET selection: MET>150, MET>250, MET>350, MET>450 GeV.

  • Table 1

    Data from Table II


    Summary of the systematic uncertainties for the largest background process (ZZ->llnunu). Statistical uncertaintes are from MC simulation sample size.

  • Table 2

    Data from Table III


    Observed yields and expected SM backgrounds in each signal region. Statistical, systematic, and luminosity uncertainteis are added in quadrature to...

  • Table 3

    Data from Table IV


    The observed and expected upper limits on the fiducial cross section at 95% C.L. for each signal region.

  • Table 4

    Data from Figure 4


    Observed 90% C.L. lower limits on the mass scale, M*, of considered effective field theories as a function of mChi....

  • Table 5

    Data from Appendix, Figure 7


    Expected 95% C.L. upper limits on the cross section times branching fraction as a function of mChi. For each operator,...

  • Table 6

    Data from Appendix, Figure 7


    Observed 95% C.L. upper limits on the cross section times branching fraction as a function of mChi. For each operator,...

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