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Search for high-mass dilepton resonances in pp collisions at $\sqrt{s}=8$  TeV with the ATLAS detector

The collaboration
Phys.Rev. D90 (2014) 052005, 2014

Abstract (data abstract)
CERN-LHC. Search for high-mass resonances decaying to dielectron or dimuon final states in proton-proton collisions at a center-of-mass energy of 8 TeV with 20.3 fb-1 in the dimuon channel and 20.5 fb-1 in the dielectron channel, collected in 2012. The final states used are 2 electrons or 2 muons. All events meet the following requirements: - At least one reconstructed primary vertex with at least associated 3 tracks having pT > 0.4 GeV. - For data, events occurred during periods of stable beam with all relevant detector sub-systems operational. Events are triggered by one of the following trigger selections: - A trigger requiring the presence of at least 2 energy deposits in the electromagnetic calorimeter, one with pT > 35 GeV, and the other with pT > 25 GeV. The shower profiles are required to be consistent with those expected for electromagnetic shower. - A trigger requiring the presence of at least one isolated muon with pT > 24 GeV or at least one muon with pT > 36 GeV. The 2 electron channel is defined as: - 2 electrons with ET > 30 GeV. - 1 "leading" electron with ET > 40 GeV. - Electrons are in pseudorapidity range < 2.5. - Electrons in pseudorapidity range [1.37,1.52] are excluded. - Electron track and cluster satisfy criteria requiring shower profiles consistent with those expected. - Minimum requirement on the amount of transition radiation for electron tracks. - At least one hit in the first layer of the pixel detector required if an active pixel layer is traversed. - Electrons are isolated within a cone of radius DeltaR = 0.2 in the (eta,phi) plane: for leading electron energy in the cone < 0.007 * ET + 5.0 GeV, for subleading electron < 0.022 * ET + 6.0 GeV. The 2 muon channel is defined as: - 2 oppositely-charged muons with pT > 25 GeV, each with a track component in both the Muon Spectrometer and the Inner Detector. - Each muon has a minimum number of hits in each ID component. - Impact parameter along the beam axis is < 1 mm, and transverse impact parameter is < 0.2 mm. - At least one muon in the pair passes a "tight" selection consisting of: >=1 hit in both trigger chamber layers; >=3 hits in each of three stations of the MS, or, for muons in the very forward region, >=2 hits in the CSC and >=3 hits in the middle and outer MS stations; Difference between ID and MS track momentum measurements is < 5 sigma. - One muon in the pair is allowed to pass a modified selection, consisting of: Muon is within pseudorapidity range < 1.05; >=5 precision hits in each of the inner and outer stations of the MS; >=1 hit in one trigger chamber layer; Difference between ID and MS track momentum measurements is < 5 sigma. In all cases, the pair candidate with the highest sum pT is selected.

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Data from Figure 1

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Z' Product of acceptance and efficiency for the dielectron and dimuon selections as a function of the SSM Z' pole...

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Data from Figure 2a

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Observed and predicted dielectron invariant mass (m_ee) distribution in the search region. The bin width is constant in log(m_ee).

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Data from Figure 2b

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Observed and predicted dimuon invariant mass (m_mumu) distribution in the search region. The bin width is constant in log(m_mumu).

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Data from Figure 4

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Median expected and observed 95% CL upper limits on the cross-section times branching ratio (sigma*B) for Z'_SSM production for the...

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Data from Figure 5

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Observed upper cross-section times branching ratio (sigma*B) limits at 95% CL for Z'_SSM, E6-motivated Z' and Z* bosons using the...

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Data from Figure 6

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Expected and observed limits at 95% CL on the strength of the Z' boson coupling relative to that of the...

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Data from Figure 7

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Expected and observed limits at 95% CL on the strength of the Z' boson coupling relative to that of the...

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Data from Figure 7

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Expected and observed limits at 95% CL on the strength of the Z' boson coupling relative to that of the...

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Data from Figure 7

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Expected and observed limits at 95% CL on the strength of the Z' boson coupling relative to that of the...

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Data from Figure 7

10.17182/hepdata.65388.v1/t10

Expected and observed limits at 95% CL on the strength of the Z' boson coupling relative to that of the...

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Data from Figure 7

10.17182/hepdata.65388.v1/t11

Expected and observed limits at 95% CL on the strength of the Z' boson coupling relative to that of the...

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Data from Figure 7

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Expected and observed limits at 95% CL on the strength of the Z' boson coupling relative to that of the...

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Data from Figure 7

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Expected and observed limits at 95% CL on the strength of the Z' boson coupling relative to that of the...

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Data from Figure 8

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Expected and observed 95% CL limits on the coupling strength of the Randall-Sundrum G* to SM particles (k/Mpl) as a...

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Data from Figure 9

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Expected and observed 95% CL upper limits on cross-section times branching ratio for quantum black hole production in the extra...

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Data from Auxiliary Figure 26

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Expected and observed 95% CL upper limits on production times branching ratio and theoretical prediction for G* production for the...

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Data from Auxiliary Figure 30

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Expected and observed 95% CL limits on technimeson R_1 in the MWT model for the combination of the dielectron and...

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