CMS-PAS-TOP-16-015 | ||
First measurement of the top quark pair production cross section in proton-proton collisions at √s= 5.02 TeV | ||
CMS Collaboration | ||
June 2016 | ||
Abstract: The top quark pair production cross section is measured for the first time in proton-proton collisions at √s= 5.02 TeV using data corresponding to an integrated luminosity of 26 pb−1. The measurement is performed by analyzing events with at least one electron and one muon of opposite charge, and at least two jets. The measured cross section is σtˉt= 82 ± 20 (stat) ± 5 (syst) ± 10 (lumi) pb, in agreement with the expectation from the standard model. | ||
Links: CDS record (PDF) ; inSPIRE record ; CADI line (restricted) ; |
Figures & Tables | Summary | Additional Figures | References | CMS Publications |
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Figures | |
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Figure 1-a:
Distributions of the jet multiplicity (a), and scalar pT sum of all jets (b) in events passing the dilepton criteria. The DY and Non W/Z backgrounds are determined from data. The last bin of the distributions contains the overflow events. |
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Figure 1-b:
Distributions of the jet multiplicity (a), and scalar pT sum of all jets (b) in events passing the dilepton criteria. The DY and Non W/Z backgrounds are determined from data. The last bin of the distributions contains the overflow events. |
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Figure 2-a:
Distributions of the invariant mass (a) and pT (b) of the dilepton after requiring at least two jets in the event. The DY and Non W/Z backgrounds are determined from data. The last bin of the distributions contains the overflow events. |
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Figure 2-b:
Distributions of the invariant mass (a) and pT (b) of the dilepton after requiring at least two jets in the event. The DY and Non W/Z backgrounds are determined from data. The last bin of the distributions contains the overflow events. |
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Figure 3:
Top quark pair production cross section in pˉp and pp collisions as a function of the centre-of-mass energy; the Tevatron combination at √s= 1.96 TeV is displayed, as well as CMS results at 7, 8 and 13TeV in the dilepton channel. The measurements are compared to the NNLO+NNLL theory predictions. |
Tables | |
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Table 1:
Selection criteria applied in the analysis. Note that electron candidates between the barrel and endcap sections of ECAL are excluded. |
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Table 2:
Summary of individual contributions to the systematic uncertainty on the σtˉt measurement. The absolute uncertainties Δσtˉt are given in pb, as well as relative uncertainties (Δσtˉt/σtˉt). The separate total systematic uncertainty without integrated luminosity, the part attributed to the integrated luminosity, and the statistical contribution are added in quadrature to obtain the total uncertainty. |
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Table 3:
The number of e±μ∓ events after final event selection expected for background and signal, and observed in data. The uncertainties represent only the statistical component. |
Summary |
In summary, the first measurement of the tˉt production cross section in proton-proton collisions at √s= 5.02 TeV is presented for events containing an electron-muon pair and at least two jets. The measurement is obtained through an event-counting analysis based on a data sample corresponding to an integrated luminosity of 26 ± 3 pb−1. The result is 82 pb, with a total relative uncertainty of 28%. This measurement is consistent with the SM prediction. |
Additional Figures | |
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Additional Figure 1:
Initial partonic states yielding tˉt pairs in pp collisions at √s= 5.02 TeV simulated at NLO with POWHEG and the NNPDF3.0 PDF set. The fraction (in %) of each initial state is represented. |
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Additional Figure 2:
Expected average momentum of the incoming partons measured with respect to the proton momentum, for collisions at √s= 5.02 TeV and 13 TeV, as simulated by POWHEG and the NNPDF3.0 set. |
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Additional Figure 3:
Average momentum transfer in the partonic collision yielding a tˉt pair for collisions at √s= 5.02 TeV and 13 TeV, as simulated by POWHEG and the NNPDF3.0 set. |
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Additional Figure 4:
Event display of a candidate tˉt event selected in the √s= 5.02 TeV dataset recorded by CMS. The figure depicts the CMS sub-detectors in the ρ-ϕ plane. Calorimetric energy deposits in ECAL (HCAL) are depicted as red (blue) bars with a height proportional to the magnitude of the deposit. Tracks are represented by green (red) lines if reconstructed from tracker (tracker+muon system) hits. The measured kinematics of the reconstructed electron, muon, jets and missing transverse energy (EmissT) are represented next to each object. |
References | ||||
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Compact Muon Solenoid LHC, CERN |
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