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| CMS-PAS-TOP-17-018 | ||
| Measurement of the production cross section for single top quarks in association with W bosons in pp collisions at $\sqrt{s}= $ 13 TeV | ||
| CMS Collaboration | ||
| September 2017 | ||
| Abstract: A measurement of the associated production of a single top quark and a W boson in pp collisions at $\sqrt{s}= $ 13 TeV with the CMS experiment at the CERN LHC is presented. The data set, collected in 2016, corresponds to an integrated luminosity of 35.9 fb$^{-1}$. The measurement is performed in the dilepton final state, using events with one electron and one muon. A multivariate discriminant, exploiting kinematic properties of events, is used to separate the signal from the dominant ${\rm t\bar{t}}$ background. The measured cross section of $\sigma = $ 63.1 $\pm$ 1.8 (stat) $\pm$ 6.0 ( (syst) $\pm$ 2.1 (lumi) pb is in agreement with the standard model expectation. | ||
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Links:
CDS record (PDF) ;
inSPIRE record ;
CADI line (restricted) ;
These preliminary results are superseded in this paper, JHEP 10 (2018) 117. The superseded preliminary plots can be found here. |
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| Figures | |
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Figure 1:
Leading order Feynman diagrams for single top quark production in the tW mode, the charge-conjugate modes are implicitly included. |
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Figure 1-a:
Leading order Feynman diagrams for single top quark production in the tW mode, the charge-conjugate modes are implicitly included. |
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Figure 1-b:
Leading order Feynman diagrams for single top quark production in the tW mode, the charge-conjugate modes are implicitly included. |
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Figure 2:
Comparison of several lepton kinematic variables for the observed data and simulated events after the dilepton selection is applied. The error band includes the statistical and all systematic uncertainties but the ones from background normalization and luminosity. The bottom of each panel shows the ratios of data to the sum of the expected yields. |
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Figure 2-a:
Comparison of several lepton kinematic variables for the observed data and simulated events after the dilepton selection is applied. The error band includes the statistical and all systematic uncertainties but the ones from background normalization and luminosity. The bottom of each panel shows the ratios of data to the sum of the expected yields. |
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Figure 2-b:
Comparison of several lepton kinematic variables for the observed data and simulated events after the dilepton selection is applied. The error band includes the statistical and all systematic uncertainties but the ones from background normalization and luminosity. The bottom of each panel shows the ratios of data to the sum of the expected yields. |
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Figure 2-c:
Comparison of several lepton kinematic variables for the observed data and simulated events after the dilepton selection is applied. The error band includes the statistical and all systematic uncertainties but the ones from background normalization and luminosity. The bottom of each panel shows the ratios of data to the sum of the expected yields. |
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Figure 2-d:
Comparison of several lepton kinematic variables for the observed data and simulated events after the dilepton selection is applied. The error band includes the statistical and all systematic uncertainties but the ones from background normalization and luminosity. The bottom of each panel shows the ratios of data to the sum of the expected yields. |
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Figure 2-e:
Comparison of several lepton kinematic variables for the observed data and simulated events after the dilepton selection is applied. The error band includes the statistical and all systematic uncertainties but the ones from background normalization and luminosity. The bottom of each panel shows the ratios of data to the sum of the expected yields. |
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Figure 2-f:
Comparison of several lepton kinematic variables for the observed data and simulated events after the dilepton selection is applied. The error band includes the statistical and all systematic uncertainties but the ones from background normalization and luminosity. The bottom of each panel shows the ratios of data to the sum of the expected yields. |
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Figure 3:
Yields observed in data compared with those expected from simulation as a function of the number of jets and number of b-tagged jets for events passing the baseline dileptonic selection. The error band includes the statistical and all systematic uncertainties but the ones from background normalization and luminosity. The bottom of each panel shows the ratios of data to the sum of the expected yields. |
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Figure 4:
Most discriminat variables used for the training of the BDT in the 1j1b category. The error band includes the statistical and all systematic uncertainties but the ones from background normalization and luminosity. The bottom of each panel shows the ratios of data to the sum of the expected yields. |
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Figure 4-a:
Most discriminat variables used for the training of the BDT in the 1j1b category. The error band includes the statistical and all systematic uncertainties but the ones from background normalization and luminosity. The bottom of each panel shows the ratios of data to the sum of the expected yields. |
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Figure 4-b:
Most discriminat variables used for the training of the BDT in the 1j1b category. The error band includes the statistical and all systematic uncertainties but the ones from background normalization and luminosity. The bottom of each panel shows the ratios of data to the sum of the expected yields. |
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Figure 4-c:
Most discriminat variables used for the training of the BDT in the 1j1b category. The error band includes the statistical and all systematic uncertainties but the ones from background normalization and luminosity. The bottom of each panel shows the ratios of data to the sum of the expected yields. |
png pdf |
Figure 4-d:
Most discriminat variables used for the training of the BDT in the 1j1b category. The error band includes the statistical and all systematic uncertainties but the ones from background normalization and luminosity. The bottom of each panel shows the ratios of data to the sum of the expected yields. |
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Figure 5:
Comparison of the BDT output in the 1j1b (left) and 2j1b (center) regions and the $ {p_{\mathrm {T}}} $ of the subleading jet in the 2j2b region (right) distributions after the fit is performed for the observed data and simulated events. The error band includes the statistical and systematic uncertainties. The bottom of each panel shows the ratios of data to the sum of the expected yields. |
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Figure 5-a:
Comparison of the BDT output in the 1j1b (left) and 2j1b (center) regions and the $ {p_{\mathrm {T}}} $ of the subleading jet in the 2j2b region (right) distributions after the fit is performed for the observed data and simulated events. The error band includes the statistical and systematic uncertainties. The bottom of each panel shows the ratios of data to the sum of the expected yields. |
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Figure 5-b:
Comparison of the BDT output in the 1j1b (left) and 2j1b (center) regions and the $ {p_{\mathrm {T}}} $ of the subleading jet in the 2j2b region (right) distributions after the fit is performed for the observed data and simulated events. The error band includes the statistical and systematic uncertainties. The bottom of each panel shows the ratios of data to the sum of the expected yields. |
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Figure 5-c:
Comparison of the BDT output in the 1j1b (left) and 2j1b (center) regions and the $ {p_{\mathrm {T}}} $ of the subleading jet in the 2j2b region (right) distributions after the fit is performed for the observed data and simulated events. The error band includes the statistical and systematic uncertainties. The bottom of each panel shows the ratios of data to the sum of the expected yields. |
| Tables | |
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Table 1:
Estimation of the effect of each source of systematic uncertainty to the fit. |
| Summary |
| The full data set recorded by CMS at 13 TeV during 2016, corresponding to an integrated luminosity of 35.9 fb$^{-1}$, is used to measure the tW production cross section in the $\mathrm{e^{\pm}}\mu^{\mp}$ channel. The signal is measured using a maximum likelihood fit to the distribution of BDT discriminants in the 1j1b and 2j1b categories and the subleading jet $ {p_{\mathrm{T}}} $ distribution in the 2j2b category. The measured cross section of the tW production is found to be $\sigma = $ 63.1 $\pm$ 1.8 (stat) $\pm$ 6.0 ( (syst) $\pm$ 2.1 (lumi) pb. A relative uncertainty of 10% in the tW production cross section is achieved. This is the first measurement of this process by the CMS experiment at $ \sqrt{s} = $ 13 TeV. The measured cross section is consistent with the standard model prediction of 71.7 $\pm$ 1.8 (scale) $\pm$ 3.4 (PDF) pb and with a similar measurement by the ATLAS collaboration [13]. |
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