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| CMS-TOP-20-004 ; CERN-EP-2021-244 | ||
| Measurement of the inclusive $\mathrm{t\bar{t}}$ production cross section in proton-proton collisions at $\sqrt{s} = $ 5.02 TeV | ||
| CMS Collaboration | ||
| 16 December 2021 | ||
| JHEP 04 (2022) 144 | ||
| Abstract: The top quark pair production cross section is measured in proton-proton collisions at a center-of-mass energy of 5.02 TeV. The data were collected in a special LHC low-energy and low-intensity run in 2017, and correspond to an integrated luminosity of 302 pb$^{-1}$. The measurement is performed using events with one electron and one muon of opposite charge, and at least two jets. The measured cross section is 60.7 $\pm$ 5.0 (stat) $\pm$ 2.8 (syst) $\pm$ 1.1 (lumi) pb. To reduce the statistical uncertainty, a combination with the result in the single lepton + jets channel, based on data collected in 2015 at the same center-of-mass energy and corresponding to an integrated luminosity of 27.4 pb$^{-1}$, is then performed. The resulting measured value is 63.0 $\pm$ 4.1 (stat) $\pm$ 3.0 (syst+lumi) pb, in agreement with the standard model prediction of 66.8$^{+2.9}_{-3.1}$ pb. | ||
| Links: e-print arXiv:2112.09114 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; HepData record ; CADI line (restricted) ; | ||
| Figures | |
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Figure 1:
Leading lepton ${p_{\mathrm {T}}}$ (upper left), sub-leading lepton ${p_{\mathrm {T}}}$ (upper right), leading jet ${p_{\mathrm {T}}}$ (lower left), and jet multiplicity (lower right) in the selected events. The hatched band corresponds to systematic and statistical uncertainties summed in quadrature. The lower panels show the data-to-prediction ratio. The last bin in each distribution includes overflow events. |
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Figure 1-a:
Leading lepton ${p_{\mathrm {T}}}$ in the selected events. The hatched band corresponds to systematic and statistical uncertainties summed in quadrature. The lower panel showa the data-to-prediction ratio. The last bin includes overflow events. |
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Figure 1-b:
Sub-leading lepton ${p_{\mathrm {T}}}$ in the selected events. The hatched band corresponds to systematic and statistical uncertainties summed in quadrature. The lower panel showa the data-to-prediction ratio. The last bin includes overflow events. |
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Figure 1-c:
Leading jet ${p_{\mathrm {T}}}$ in the selected events. The hatched band corresponds to systematic and statistical uncertainties summed in quadrature. The lower panel showa the data-to-prediction ratio. The last bin includes overflow events. |
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Figure 1-d:
Jet multiplicity in the selected events. The hatched band corresponds to systematic and statistical uncertainties summed in quadrature. The lower panel showa the data-to-prediction ratio. The last bin includes overflow events. |
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Figure 2:
Inclusive ${\mathrm{t} {}\mathrm{\bar{t}}}$ cross section in pp collisions as a function of the center-of-mass energy in the separate $\ell $+jets and dilepton channels along with the combined measurement at 5.02 TeV presented in this analysis are displayed. Some of the previous CMS measurements at $\sqrt {s} = $ 7, 8 [6,7], and 13 TeV [2,11] are also shown. The NNLO+NNLL theoretical prediction [27] using the NNPDF3.1 [23] PDF set with $ {{\alpha _\mathrm {S}} (m_{\mathrm{Z}})} = $ 0.118 and $ {m_{\mathrm{t}}} = $ 172.5 GeV is shown in the main plot. In the inset, predictions at 5.02 TeV using the MSHT20 [48], CT18 [49], and ABMP16 [50] NNLO PDF sets, the latter with $ {{\alpha _\mathrm {S}} (m_{\mathrm{Z}})} = $ 0.115 and $ {m_{\mathrm{t}}} = $ 170.4 GeV, are compared, along with the NNPDF3.1 NNLO prediction, to the individual and combined results from this analysis. The vertical bars and bands represent the total uncertainties in the data and in the predictions, respectively. Points corresponding to measurements at the same $\sqrt {s}$ are horizontally shifted for better readability. |
| Tables | |
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Table 1:
Summary of MC samples used to model the signal and background processes. The column "Cross section order'' corresponds to the QCD or electroweak (EW) precision used to normalize the distributions provided by the generators. Where no reference is given, the precision of the MC simulation is kept. |
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Table 2:
Summary of the systematic and statistical relative uncertainties for the ${\mathrm{t} {}\mathrm{\bar{t}}}$ cross section measurement. |
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Table 3:
Event yields for all the processes at the final level of selection. The uncertainty corresponds to the quadratic sum of the statistical and systematic sources. |
| Summary |
| A measurement of the top quark pair production cross section at a center-of-mass energy of 5.02 TeV is presented for events with one electron and one muon of opposite charge, and at least two jets, using proton-proton collisions collected by the CMS experiment in 2017 and corresponding to an integrated luminosity of 302 pb$^{-1}$. The measured cross section is found to be ${\sigma_\mathrm{t\bar{t}}} =$ 60.7 $\pm$ 5.0 (stat) $\pm$ 2.8 (syst) $\pm$ 1.1 (lumi) pb. To reduce the statistical uncertainty in the result, a combination with the single lepton + jets measurement, using a data set collected in 2015 at the same center-of-mass energy and corresponding to an integrated luminosity of 27.4 pb$^{-1}$, is performed. A measurement of 63.0 $\pm$ 4.1 (stat) $\pm$ 3.0 (syst+lumi) pb is obtained, in agreement with the prediction from the standard model of 66.8$^{+2.9}_{-3.1}$ pb. |
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