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| CMS-PAS-TOP-19-003 | ||
| Measurement of differential cross sections for single top quark production in association with a W boson at $\sqrt{s}= $ 13 TeV | ||
| CMS Collaboration | ||
| March 2020 | ||
| Abstract: Measurements are presented of normalized differential cross sections for the production of single top quarks in association with a W boson, in proton-proton collisions at a centre-of-mass energy of 13 TeV. Events containing one muon and one electron in the final state are analyzed. A fiducial region is defined according to the detector acceptance, and the requirement of exactly one b-tagged jet. The presence of lower-energy jets is vetoed to reduce the contribution from backgrounds. The resulting distributions are unfolded to particle-level and compared with predictions calculations at next-to-leading order in perturbative QCD. Within current uncertainties, all the predictions agree with the data. | ||
| Links: CDS record (PDF) ; inSPIRE record ; CADI line (restricted) ; | ||
| 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 diagram for single top quark production in the tW mode. The charge-conjugate mode is implicitly included. |
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Figure 1-b:
Leading order Feynman diagram for single top quark production in the tW mode. The charge-conjugate mode is implicitly included. |
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Figure 2:
Feynman diagrams for tW single top quark production at NLO that are removed from the signal definition in the DR scheme, the charge-conjugate modes are implicitly included. |
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Figure 2-a:
Feynman diagram for tW single top quark production at NLO that is removed from the signal definition in the DR scheme, the charge-conjugate mode is implicitly included. |
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Figure 2-b:
Feynman diagram for tW single top quark production at NLO that is removed from the signal definition in the DR scheme, the charge-conjugate mode is implicitly included. |
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Figure 2-c:
Feynman diagram for tW single top quark production at NLO that is removed from the signal definition in the DR scheme, the charge-conjugate mode is implicitly included. |
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Figure 3:
Left: 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 dilepton selection. The error band includes the statistical and all systematic uncertainties, except those from background normalization. Right: yields observed in data, compared with those expected from simulation, as a function of the number of loose jets for events passing the ${\mathrm{e^{\pm}} {\mu^{\mp}}}$ selection in the 1j1b region. The hatched band includes the statistical and all systematic uncertainties. The bottom of the panel shows the ratio of data to the sum of the expected yields. |
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Figure 3-a:
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 dilepton selection. The error band includes the statistical and all systematic uncertainties, except those from background normalization. The bottom of the panel shows the ratio of data to the sum of the expected yields. |
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Figure 3-b:
Yields observed in data, compared with those expected from simulation, as a function of the number of loose jets for events passing the ${\mathrm{e^{\pm}} {\mu^{\mp}}}$ selection in the 1j1b region. The hatched band includes the statistical and all systematic uncertainties. The bottom of the panel shows the ratio of data to the sum of the expected yields. |
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Figure 4:
Yields observed in data, compared with those expected from simulation, as a function of different observables for the selected events. The hatched bands include the statistical and all systematic uncertainties. The last bin of each contribution contains overflow events. The bottom of each panel shows the ratios of data to the sum of the expected yields. |
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Figure 4-a:
Yields observed in data, compared with those expected from simulation, as a function of one of the observables for the selected events. The hatched bands include the statistical and all systematic uncertainties. The last bin contains overflow events. The bottom panel shows the ratio of data to the sum of the expected yields. |
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Figure 4-b:
Yields observed in data, compared with those expected from simulation, as a function of one of the observables for the selected events. The hatched bands include the statistical and all systematic uncertainties. The last bin contains overflow events. The bottom panel shows the ratio of data to the sum of the expected yields. |
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Figure 4-c:
Yields observed in data, compared with those expected from simulation, as a function of one of the observables for the selected events. The hatched bands include the statistical and all systematic uncertainties. The last bin contains overflow events. The bottom panel shows the ratio of data to the sum of the expected yields. |
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Figure 4-d:
Yields observed in data, compared with those expected from simulation, as a function of one of the observables for the selected events. The hatched bands include the statistical and all systematic uncertainties. The last bin contains overflow events. The bottom panel shows the ratio of data to the sum of the expected yields. |
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Figure 4-e:
Yields observed in data, compared with those expected from simulation, as a function of one of the observables for the selected events. The hatched bands include the statistical and all systematic uncertainties. The last bin contains overflow events. The bottom panel shows the ratio of data to the sum of the expected yields. |
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Figure 4-f:
Yields observed in data, compared with those expected from simulation, as a function of one of the observables for the selected events. The hatched bands include the statistical and all systematic uncertainties. The last bin contains overflow events. The bottom panel shows the ratio of data to the sum of the expected yields. |
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Figure 5:
Left: normalized differential tW production cross section as a function of the ${p_{\mathrm {T}}}$ of the leading lepton (top), ${p_{\mathrm {T}}}$ of the jet (middle) and ${\Delta \varphi (\mathrm{e^{\pm}}, {\mu^{\mp}})}$ (bottom). The solid band represents the total uncertainty. Predictions from POWHEG and MadGraph5_aMC@NLO are also shown. In the bottom panel, the ratio between predictions and data is shown. Right: total, systematic, statistical and individual leading (averaging over all bins) sources of uncertainty as a function of each observable. |
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Figure 5-a:
Normalized differential tW production cross section as a function of the ${p_{\mathrm {T}}}$ of the leading lepton. The solid band represents the total uncertainty. Predictions from POWHEG and MadGraph5_aMC@NLO are also shown. In the bottom panel, the ratio between predictions and data is shown. |
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Figure 5-b:
Total, systematic, statistical and individual leading (averaging over all bins) sources of uncertainty as a function of the ${p_{\mathrm {T}}}$ of the leading lepton. |
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Figure 5-c:
Normalized differential tW production cross section as a function of ${p_{\mathrm {T}}}$ of the jet. The solid band represents the total uncertainty. Predictions from POWHEG and MadGraph5_aMC@NLO are also shown. In the bottom panel, the ratio between predictions and data is shown. |
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Figure 5-d:
Total, systematic, statistical and individual leading (averaging over all bins) sources of uncertainty as a function of ${p_{\mathrm {T}}}$ of the jet. |
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Figure 5-e:
Normalized differential tW production cross section as a function of ${\Delta \varphi (\mathrm{e^{\pm}}, {\mu^{\mp}})}$. The solid band represents the total uncertainty. Predictions from POWHEG and MadGraph5_aMC@NLO are also shown. In the bottom panel, the ratio between predictions and data is shown. |
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Figure 5-f:
Total, systematic, statistical and individual leading (averaging over all bins) sources of uncertainty as a function of ${\Delta \varphi (\mathrm{e^{\pm}}, {\mu^{\mp}})}$. |
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Figure 6:
Left: normalized differential tW production cross section as a function of ${p_\text {Z}(\mathrm{e^{\pm}}, {\mu^{\mp}}, j)}$ (top), ${m(\mathrm{e^{\pm}}, {\mu^{\mp}},j)}$ (middle) and ${m_{\text {T}}(\mathrm{e^{\pm}}, {\mu^{\mp}},j, {{p_{\mathrm {T}}} ^\text {miss}})}$ (bottom). The solid band represents the total uncertainty. Predictions from POWHEG and MadGraph5_aMC@NLO are also shown. In the bottom panel, the ratio between predictions and data is shown. Right: total, systematic, statistical and individual leading (averaging over all bins) sources of uncertainty as a function of each observable. |
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Figure 6-a:
Normalized differential tW production cross section as a function of ${p_\text {Z}(\mathrm{e^{\pm}}, {\mu^{\mp}}, j)}$. The solid band represents the total uncertainty. Predictions from POWHEG and MadGraph5_aMC@NLO are also shown. In the bottom panel, the ratio between predictions and data is shown. |
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Figure 6-b:
Total, systematic, statistical and individual leading (averaging over all bins) sources of uncertainty as a function of ${p_\text {Z}(\mathrm{e^{\pm}}, {\mu^{\mp}}, j)}$. |
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Figure 6-c:
Normalized differential tW production cross section as a function of ${m(\mathrm{e^{\pm}}, {\mu^{\mp}},j)}$. The solid band represents the total uncertainty. Predictions from POWHEG and MadGraph5_aMC@NLO are also shown. In the bottom panel, the ratio between predictions and data is shown. |
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Figure 6-d:
Total, systematic, statistical and individual leading (averaging over all bins) sources of uncertainty as a function of ${m(\mathrm{e^{\pm}}, {\mu^{\mp}},j)}$. |
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Figure 6-e:
Normalized differential tW production cross section as a function of ${m_{\text {T}}(\mathrm{e^{\pm}}, {\mu^{\mp}},j, {{p_{\mathrm {T}}} ^\text {miss}})}$. The solid band represents the total uncertainty. Predictions from POWHEG and MadGraph5_aMC@NLO are also shown. In the bottom panel, the ratio between predictions and data is shown. |
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Figure 6-f:
Total, systematic, statistical and individual leading (averaging over all bins) sources of uncertainty as a function of ${m_{\text {T}}(\mathrm{e^{\pm}}, {\mu^{\mp}},j, {{p_{\mathrm {T}}} ^\text {miss}})}$. |
| Tables | |
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Table 1:
Definition of the fiducial region. |
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Table 2:
Selection requirements of particle-level objects. |
| Summary |
| The measurement of the normalized differential cross section of the production of a top quark in association with a W boson using 35.9 fb$^{-1}$ of data recorded by CMS has been presented for a final state containing an electron and a muon. The measurements are made as a function of various properties of the event: the transverse momentum of the leading lepton, the transverse momentum of the jet; the difference in the $\varphi$ angle of the muon and the electron; the longitudinal momentum of the muon, the electron and the jet; the invariant mass of the muon, electron and the jet; and the transverse mass of the electron, the muon, the jet, and the missing transverse momentum. The main sources of uncertainty, both in the jet reconstruction and the theoretical modeling, are driven by the overwhelming $ \mathrm{t\bar{t}}$ background. The results obtained are, in general, consistent with the expectations from the two models used for the modeling of the tW signal, POWHEG and MadGraph5+MCatNLO. |
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