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| CMS-TOP-15-018 ; CERN-EP-2019-270 | ||
| Measurement of the top quark forward-backward production asymmetry and the anomalous chromoelectric and chromomagnetic moments in pp collisions at $\sqrt{s} = $ 13 TeV | ||
| CMS Collaboration | ||
| 19 December 2019 | ||
| JHEP 06 (2020) 146 | ||
| Abstract: The parton-level top quark (t) forward-backward asymmetry and the anomalous chromoelectric (${\hat{d}_{\mathrm{t}}}$) and chromomagnetic (${\hat{\mu}_{\mathrm{t}}}$) moments have been measured using LHC pp collisions at a center-of-mass energy of 13 TeV, collected in the CMS detector in a data sample corresponding to an integrated luminosity of 35.9 fb$^{-1}$. The linearized variable ${A^{(1)}_\mathrm{FB}}$ is used to approximate the asymmetry. Candidate $\mathrm{t\bar{t}}$ events decaying to a muon or electron and jets in final states with low and high Lorentz boosts are selected and reconstructed using a fit of the kinematic distributions of the decay products to those expected for $\mathrm{t\bar{t}}$ final states. The values found for the parameters are ${A^{(1)}_\mathrm{FB}}=$ 0.048$^{+0.095}_{-0.087}$ (stat) $^{+0.020}_{-0.029}$ (syst), ${\hat{\mu}_{\mathrm{t}}}=-0.024^{+0.013}_{-0.009}$ (stat) $^{+0.016}_{-0.011}$ (syst), and a limit is placed on the magnitude of $|{{\hat{d}_{\mathrm{t}}}}| < $ 0.03 at 95% confidence level. | ||
| Links: e-print arXiv:1912.09540 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; HepData record ; CADI line (restricted) ; | ||
| Figures | |
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Figure 1:
(a) Feynman diagrams for LO ${{\mathrm{q} \mathrm{\bar{q}}}}$- and ${{\mathrm{g}}{\mathrm{g}}}$-initiated ${\mathrm{t} {}\mathrm{\bar{t}}}$ subprocesses, and (b) example diagrams for the NLO ${{\mathrm{q}}{\mathrm{g}}}$-initiated subprocess. |
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Figure 2:
Production angle $\theta ^*$ in a $ {\mathrm{q} \mathrm{\bar{q}}} \to {\mathrm{t} {}\mathrm{\bar{t}}} $ event defined in the ${\mathrm{t} {}\mathrm{\bar{t}}}$ center-of-mass frame. |
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Figure 3:
The generator-level ${c^{*}}$ (upper left), ${x_{\text {F}}}$ (upper right), and ${m_{{\mathrm{t} {}\mathrm{\bar{t}}}}}$ (lower left) distributions normalized to unity for the subprocesses ${\mathrm{q} \mathrm{\bar{q}}}$, ${\mathrm{q}}{\mathrm{g}}$, and ${\mathrm{g}}{\mathrm{g}}\to {\mathrm{t} {}\mathrm{\bar{t}}} $. The dilution factor, when taking the longitudinal direction of the ${\mathrm{t} {}\mathrm{\bar{t}}}$ pair in the lab frame as the quark direction for ${\mathrm{q} \mathrm{\bar{q}}}$ events, is shown in the lower right plot as a function of ${{| {x_{\text {F}}} |}}$. |
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Figure 3-a:
The generator-level ${c^{*}}$ (upper left), ${x_{\text {F}}}$ (upper right), and ${m_{{\mathrm{t} {}\mathrm{\bar{t}}}}}$ (lower left) distributions normalized to unity for the subprocesses ${\mathrm{q} \mathrm{\bar{q}}}$, ${\mathrm{q}}{\mathrm{g}}$, and ${\mathrm{g}}{\mathrm{g}}\to {\mathrm{t} {}\mathrm{\bar{t}}} $. The dilution factor, when taking the longitudinal direction of the ${\mathrm{t} {}\mathrm{\bar{t}}}$ pair in the lab frame as the quark direction for ${\mathrm{q} \mathrm{\bar{q}}}$ events, is shown in the lower right plot as a function of ${{| {x_{\text {F}}} |}}$. |
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Figure 3-b:
The generator-level ${c^{*}}$ (upper left), ${x_{\text {F}}}$ (upper right), and ${m_{{\mathrm{t} {}\mathrm{\bar{t}}}}}$ (lower left) distributions normalized to unity for the subprocesses ${\mathrm{q} \mathrm{\bar{q}}}$, ${\mathrm{q}}{\mathrm{g}}$, and ${\mathrm{g}}{\mathrm{g}}\to {\mathrm{t} {}\mathrm{\bar{t}}} $. The dilution factor, when taking the longitudinal direction of the ${\mathrm{t} {}\mathrm{\bar{t}}}$ pair in the lab frame as the quark direction for ${\mathrm{q} \mathrm{\bar{q}}}$ events, is shown in the lower right plot as a function of ${{| {x_{\text {F}}} |}}$. |
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Figure 3-c:
The generator-level ${c^{*}}$ (upper left), ${x_{\text {F}}}$ (upper right), and ${m_{{\mathrm{t} {}\mathrm{\bar{t}}}}}$ (lower left) distributions normalized to unity for the subprocesses ${\mathrm{q} \mathrm{\bar{q}}}$, ${\mathrm{q}}{\mathrm{g}}$, and ${\mathrm{g}}{\mathrm{g}}\to {\mathrm{t} {}\mathrm{\bar{t}}} $. The dilution factor, when taking the longitudinal direction of the ${\mathrm{t} {}\mathrm{\bar{t}}}$ pair in the lab frame as the quark direction for ${\mathrm{q} \mathrm{\bar{q}}}$ events, is shown in the lower right plot as a function of ${{| {x_{\text {F}}} |}}$. |
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Figure 3-d:
The generator-level ${c^{*}}$ (upper left), ${x_{\text {F}}}$ (upper right), and ${m_{{\mathrm{t} {}\mathrm{\bar{t}}}}}$ (lower left) distributions normalized to unity for the subprocesses ${\mathrm{q} \mathrm{\bar{q}}}$, ${\mathrm{q}}{\mathrm{g}}$, and ${\mathrm{g}}{\mathrm{g}}\to {\mathrm{t} {}\mathrm{\bar{t}}} $. The dilution factor, when taking the longitudinal direction of the ${\mathrm{t} {}\mathrm{\bar{t}}}$ pair in the lab frame as the quark direction for ${\mathrm{q} \mathrm{\bar{q}}}$ events, is shown in the lower right plot as a function of ${{| {x_{\text {F}}} |}}$. |
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Figure 4:
Reconstructed ${c^{*}_{\mathrm {r}}}$ (upper), $ {| {x_{\mathrm {r}}} |}$ (middle), and ${m_{\mathrm {r}}}$ (lower) for events passing type-1 $\mu$+jets (left column) and e+jets (right column) selection criteria. The uncertainty pictured in the hatched bands represents just the statistical contributions. The multijet background is estimated from data, as discussed in Section 6. The lower panels in each figure show the ratio of data to MC expectation in each bin, and the last bins of the $ {| {x_{\mathrm {r}}} |}$ and ${m_{\mathrm {r}}}$ plots include overflow. |
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Figure 4-a:
Reconstructed ${c^{*}_{\mathrm {r}}}$ (upper), $ {| {x_{\mathrm {r}}} |}$ (middle), and ${m_{\mathrm {r}}}$ (lower) for events passing type-1 $\mu$+jets (left column) and e+jets (right column) selection criteria. The uncertainty pictured in the hatched bands represents just the statistical contributions. The multijet background is estimated from data, as discussed in Section 6. The lower panels in each figure show the ratio of data to MC expectation in each bin, and the last bins of the $ {| {x_{\mathrm {r}}} |}$ and ${m_{\mathrm {r}}}$ plots include overflow. |
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Figure 4-b:
Reconstructed ${c^{*}_{\mathrm {r}}}$ (upper), $ {| {x_{\mathrm {r}}} |}$ (middle), and ${m_{\mathrm {r}}}$ (lower) for events passing type-1 $\mu$+jets (left column) and e+jets (right column) selection criteria. The uncertainty pictured in the hatched bands represents just the statistical contributions. The multijet background is estimated from data, as discussed in Section 6. The lower panels in each figure show the ratio of data to MC expectation in each bin, and the last bins of the $ {| {x_{\mathrm {r}}} |}$ and ${m_{\mathrm {r}}}$ plots include overflow. |
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Figure 4-c:
Reconstructed ${c^{*}_{\mathrm {r}}}$ (upper), $ {| {x_{\mathrm {r}}} |}$ (middle), and ${m_{\mathrm {r}}}$ (lower) for events passing type-1 $\mu$+jets (left column) and e+jets (right column) selection criteria. The uncertainty pictured in the hatched bands represents just the statistical contributions. The multijet background is estimated from data, as discussed in Section 6. The lower panels in each figure show the ratio of data to MC expectation in each bin, and the last bins of the $ {| {x_{\mathrm {r}}} |}$ and ${m_{\mathrm {r}}}$ plots include overflow. |
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Figure 4-d:
Reconstructed ${c^{*}_{\mathrm {r}}}$ (upper), $ {| {x_{\mathrm {r}}} |}$ (middle), and ${m_{\mathrm {r}}}$ (lower) for events passing type-1 $\mu$+jets (left column) and e+jets (right column) selection criteria. The uncertainty pictured in the hatched bands represents just the statistical contributions. The multijet background is estimated from data, as discussed in Section 6. The lower panels in each figure show the ratio of data to MC expectation in each bin, and the last bins of the $ {| {x_{\mathrm {r}}} |}$ and ${m_{\mathrm {r}}}$ plots include overflow. |
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Figure 4-e:
Reconstructed ${c^{*}_{\mathrm {r}}}$ (upper), $ {| {x_{\mathrm {r}}} |}$ (middle), and ${m_{\mathrm {r}}}$ (lower) for events passing type-1 $\mu$+jets (left column) and e+jets (right column) selection criteria. The uncertainty pictured in the hatched bands represents just the statistical contributions. The multijet background is estimated from data, as discussed in Section 6. The lower panels in each figure show the ratio of data to MC expectation in each bin, and the last bins of the $ {| {x_{\mathrm {r}}} |}$ and ${m_{\mathrm {r}}}$ plots include overflow. |
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Figure 4-f:
Reconstructed ${c^{*}_{\mathrm {r}}}$ (upper), $ {| {x_{\mathrm {r}}} |}$ (middle), and ${m_{\mathrm {r}}}$ (lower) for events passing type-1 $\mu$+jets (left column) and e+jets (right column) selection criteria. The uncertainty pictured in the hatched bands represents just the statistical contributions. The multijet background is estimated from data, as discussed in Section 6. The lower panels in each figure show the ratio of data to MC expectation in each bin, and the last bins of the $ {| {x_{\mathrm {r}}} |}$ and ${m_{\mathrm {r}}}$ plots include overflow. |
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Figure 5:
Data/MC comparison of reconstructed ${c^{*}_{\mathrm {r}}}$ (upper), $ {| {x_{\mathrm {r}}} |}$ (middle), and ${m_{\mathrm {r}}}$ (lower) for events passing type-2 $\mu$+jets (left column) and e+jets (right column) selection criteria. The MC signal and background show their nominal predictions, with the MC uncertainty pictured in the hatched bands representing statistical uncertainties. The contribution from multijet background is estimated from data, as discussed in Section 6. The lower panels of each figure show the ratio of the observed data to MC expectation in each bin, and the last bins of the $ {| {x_{\mathrm {r}}} |}$ and ${m_{\mathrm {r}}}$ plots include overflow. |
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Figure 5-a:
Data/MC comparison of reconstructed ${c^{*}_{\mathrm {r}}}$ (upper), $ {| {x_{\mathrm {r}}} |}$ (middle), and ${m_{\mathrm {r}}}$ (lower) for events passing type-2 $\mu$+jets (left column) and e+jets (right column) selection criteria. The MC signal and background show their nominal predictions, with the MC uncertainty pictured in the hatched bands representing statistical uncertainties. The contribution from multijet background is estimated from data, as discussed in Section 6. The lower panels of each figure show the ratio of the observed data to MC expectation in each bin, and the last bins of the $ {| {x_{\mathrm {r}}} |}$ and ${m_{\mathrm {r}}}$ plots include overflow. |
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Figure 5-b:
Data/MC comparison of reconstructed ${c^{*}_{\mathrm {r}}}$ (upper), $ {| {x_{\mathrm {r}}} |}$ (middle), and ${m_{\mathrm {r}}}$ (lower) for events passing type-2 $\mu$+jets (left column) and e+jets (right column) selection criteria. The MC signal and background show their nominal predictions, with the MC uncertainty pictured in the hatched bands representing statistical uncertainties. The contribution from multijet background is estimated from data, as discussed in Section 6. The lower panels of each figure show the ratio of the observed data to MC expectation in each bin, and the last bins of the $ {| {x_{\mathrm {r}}} |}$ and ${m_{\mathrm {r}}}$ plots include overflow. |
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Figure 5-c:
Data/MC comparison of reconstructed ${c^{*}_{\mathrm {r}}}$ (upper), $ {| {x_{\mathrm {r}}} |}$ (middle), and ${m_{\mathrm {r}}}$ (lower) for events passing type-2 $\mu$+jets (left column) and e+jets (right column) selection criteria. The MC signal and background show their nominal predictions, with the MC uncertainty pictured in the hatched bands representing statistical uncertainties. The contribution from multijet background is estimated from data, as discussed in Section 6. The lower panels of each figure show the ratio of the observed data to MC expectation in each bin, and the last bins of the $ {| {x_{\mathrm {r}}} |}$ and ${m_{\mathrm {r}}}$ plots include overflow. |
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Figure 5-d:
Data/MC comparison of reconstructed ${c^{*}_{\mathrm {r}}}$ (upper), $ {| {x_{\mathrm {r}}} |}$ (middle), and ${m_{\mathrm {r}}}$ (lower) for events passing type-2 $\mu$+jets (left column) and e+jets (right column) selection criteria. The MC signal and background show their nominal predictions, with the MC uncertainty pictured in the hatched bands representing statistical uncertainties. The contribution from multijet background is estimated from data, as discussed in Section 6. The lower panels of each figure show the ratio of the observed data to MC expectation in each bin, and the last bins of the $ {| {x_{\mathrm {r}}} |}$ and ${m_{\mathrm {r}}}$ plots include overflow. |
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Figure 5-e:
Data/MC comparison of reconstructed ${c^{*}_{\mathrm {r}}}$ (upper), $ {| {x_{\mathrm {r}}} |}$ (middle), and ${m_{\mathrm {r}}}$ (lower) for events passing type-2 $\mu$+jets (left column) and e+jets (right column) selection criteria. The MC signal and background show their nominal predictions, with the MC uncertainty pictured in the hatched bands representing statistical uncertainties. The contribution from multijet background is estimated from data, as discussed in Section 6. The lower panels of each figure show the ratio of the observed data to MC expectation in each bin, and the last bins of the $ {| {x_{\mathrm {r}}} |}$ and ${m_{\mathrm {r}}}$ plots include overflow. |
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Figure 5-f:
Data/MC comparison of reconstructed ${c^{*}_{\mathrm {r}}}$ (upper), $ {| {x_{\mathrm {r}}} |}$ (middle), and ${m_{\mathrm {r}}}$ (lower) for events passing type-2 $\mu$+jets (left column) and e+jets (right column) selection criteria. The MC signal and background show their nominal predictions, with the MC uncertainty pictured in the hatched bands representing statistical uncertainties. The contribution from multijet background is estimated from data, as discussed in Section 6. The lower panels of each figure show the ratio of the observed data to MC expectation in each bin, and the last bins of the $ {| {x_{\mathrm {r}}} |}$ and ${m_{\mathrm {r}}}$ plots include overflow. |
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Figure 6:
Data/MC comparison of reconstructed ${c^{*}_{\mathrm {r}}}$ (upper), $ {| {x_{\mathrm {r}}} |}$ (middle), and ${m_{\mathrm {r}}}$ (lower) for events passing type-3 $\mu$+jets (left column) and e+jets (right column) selection criteria. The MC signal and background show their nominal predictions, with the MC uncertainty pictured in the hatched bands representing statistical uncertainties. The contribution from multijet background is estimated from data, as discussed in Section 6. The lower panels of each figure show the ratio of the observed data to MC expectation in each bin, and the last bins of the $ {| {x_{\mathrm {r}}} |}$ and ${m_{\mathrm {r}}}$ plots include overflow. |
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Figure 6-a:
Data/MC comparison of reconstructed ${c^{*}_{\mathrm {r}}}$ (upper), $ {| {x_{\mathrm {r}}} |}$ (middle), and ${m_{\mathrm {r}}}$ (lower) for events passing type-3 $\mu$+jets (left column) and e+jets (right column) selection criteria. The MC signal and background show their nominal predictions, with the MC uncertainty pictured in the hatched bands representing statistical uncertainties. The contribution from multijet background is estimated from data, as discussed in Section 6. The lower panels of each figure show the ratio of the observed data to MC expectation in each bin, and the last bins of the $ {| {x_{\mathrm {r}}} |}$ and ${m_{\mathrm {r}}}$ plots include overflow. |
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Figure 6-b:
Data/MC comparison of reconstructed ${c^{*}_{\mathrm {r}}}$ (upper), $ {| {x_{\mathrm {r}}} |}$ (middle), and ${m_{\mathrm {r}}}$ (lower) for events passing type-3 $\mu$+jets (left column) and e+jets (right column) selection criteria. The MC signal and background show their nominal predictions, with the MC uncertainty pictured in the hatched bands representing statistical uncertainties. The contribution from multijet background is estimated from data, as discussed in Section 6. The lower panels of each figure show the ratio of the observed data to MC expectation in each bin, and the last bins of the $ {| {x_{\mathrm {r}}} |}$ and ${m_{\mathrm {r}}}$ plots include overflow. |
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Figure 6-c:
Data/MC comparison of reconstructed ${c^{*}_{\mathrm {r}}}$ (upper), $ {| {x_{\mathrm {r}}} |}$ (middle), and ${m_{\mathrm {r}}}$ (lower) for events passing type-3 $\mu$+jets (left column) and e+jets (right column) selection criteria. The MC signal and background show their nominal predictions, with the MC uncertainty pictured in the hatched bands representing statistical uncertainties. The contribution from multijet background is estimated from data, as discussed in Section 6. The lower panels of each figure show the ratio of the observed data to MC expectation in each bin, and the last bins of the $ {| {x_{\mathrm {r}}} |}$ and ${m_{\mathrm {r}}}$ plots include overflow. |
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Figure 6-d:
Data/MC comparison of reconstructed ${c^{*}_{\mathrm {r}}}$ (upper), $ {| {x_{\mathrm {r}}} |}$ (middle), and ${m_{\mathrm {r}}}$ (lower) for events passing type-3 $\mu$+jets (left column) and e+jets (right column) selection criteria. The MC signal and background show their nominal predictions, with the MC uncertainty pictured in the hatched bands representing statistical uncertainties. The contribution from multijet background is estimated from data, as discussed in Section 6. The lower panels of each figure show the ratio of the observed data to MC expectation in each bin, and the last bins of the $ {| {x_{\mathrm {r}}} |}$ and ${m_{\mathrm {r}}}$ plots include overflow. |
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Figure 6-e:
Data/MC comparison of reconstructed ${c^{*}_{\mathrm {r}}}$ (upper), $ {| {x_{\mathrm {r}}} |}$ (middle), and ${m_{\mathrm {r}}}$ (lower) for events passing type-3 $\mu$+jets (left column) and e+jets (right column) selection criteria. The MC signal and background show their nominal predictions, with the MC uncertainty pictured in the hatched bands representing statistical uncertainties. The contribution from multijet background is estimated from data, as discussed in Section 6. The lower panels of each figure show the ratio of the observed data to MC expectation in each bin, and the last bins of the $ {| {x_{\mathrm {r}}} |}$ and ${m_{\mathrm {r}}}$ plots include overflow. |
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Figure 6-f:
Data/MC comparison of reconstructed ${c^{*}_{\mathrm {r}}}$ (upper), $ {| {x_{\mathrm {r}}} |}$ (middle), and ${m_{\mathrm {r}}}$ (lower) for events passing type-3 $\mu$+jets (left column) and e+jets (right column) selection criteria. The MC signal and background show their nominal predictions, with the MC uncertainty pictured in the hatched bands representing statistical uncertainties. The contribution from multijet background is estimated from data, as discussed in Section 6. The lower panels of each figure show the ratio of the observed data to MC expectation in each bin, and the last bins of the $ {| {x_{\mathrm {r}}} |}$ and ${m_{\mathrm {r}}}$ plots include overflow. |
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Figure 7:
Neyman constructions for the ${A^{(1)}_\mathrm {FB}}$ (left) and ${\hat{\mu}_{\mathrm{t}}}$ (right) parameters of interest in groups of 1000 pseudo-experiments generated with systematic uncertainty nuisance parameters allowed to vary. The horizontal dotted lines indicate the values of the parameters determined from the fits and the vertical dotted lines indicate where these values intersect with the central value and uncertainty contours from the pseudo-experiment groups. |
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Figure 7-a:
Neyman constructions for the ${A^{(1)}_\mathrm {FB}}$ (left) and ${\hat{\mu}_{\mathrm{t}}}$ (right) parameters of interest in groups of 1000 pseudo-experiments generated with systematic uncertainty nuisance parameters allowed to vary. The horizontal dotted lines indicate the values of the parameters determined from the fits and the vertical dotted lines indicate where these values intersect with the central value and uncertainty contours from the pseudo-experiment groups. |
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Figure 7-b:
Neyman constructions for the ${A^{(1)}_\mathrm {FB}}$ (left) and ${\hat{\mu}_{\mathrm{t}}}$ (right) parameters of interest in groups of 1000 pseudo-experiments generated with systematic uncertainty nuisance parameters allowed to vary. The horizontal dotted lines indicate the values of the parameters determined from the fits and the vertical dotted lines indicate where these values intersect with the central value and uncertainty contours from the pseudo-experiment groups. |
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Figure 8:
One-dimensional likelihood profile of the ${\hat{d}_{\mathrm{t}}}$ parameter, where the change in the minimum log likelihood from its global minimum ($-2\Delta \ln{L}$) is shown on the $y$-axis as a function of $ {| {\hat{d}_{\mathrm{t}}} |}$. The dashed and solid lines show the intersections at $-2\Delta \ln{L}=$ 1.0 and 3.84, corresponding to the one-sided limits on $ {| {\hat{d}_{\mathrm{t}}} |}$ at the 68 and 95% confidence limits, respectively. |
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Figure 9:
Comparisons of fitted data and MC expectations as a function of template bin number for the ${A^{(1)}_\mathrm {FB}}$ parameter extraction. The plots show events in the type-1 (upper row) and type-2 (lower row) $\mu$+jets (left column) and e+jets (right column) channels, all summed over lepton charge. The MC uncertainty pictured in the hatched bands represents the total (statistical and systematic) uncertainty. The vertical solid, dashed, and dot-dashed lines indicate the edges of the bins in ${x_{\mathrm {r}}}$ and ${m_{\mathrm {r}}}$ and the midpoints of the ${c^{*}}$ distributions, respectively, corresponding to the binning schemes listed in Tables 2-5 in Appendix B. |
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Figure 9-a:
Comparisons of fitted data and MC expectations as a function of template bin number for the ${A^{(1)}_\mathrm {FB}}$ parameter extraction. The plots show events in the type-1 (upper row) and type-2 (lower row) $\mu$+jets (left column) and e+jets (right column) channels, all summed over lepton charge. The MC uncertainty pictured in the hatched bands represents the total (statistical and systematic) uncertainty. The vertical solid, dashed, and dot-dashed lines indicate the edges of the bins in ${x_{\mathrm {r}}}$ and ${m_{\mathrm {r}}}$ and the midpoints of the ${c^{*}}$ distributions, respectively, corresponding to the binning schemes listed in Tables 2-5 in Appendix B. |
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Figure 9-b:
Comparisons of fitted data and MC expectations as a function of template bin number for the ${A^{(1)}_\mathrm {FB}}$ parameter extraction. The plots show events in the type-1 (upper row) and type-2 (lower row) $\mu$+jets (left column) and e+jets (right column) channels, all summed over lepton charge. The MC uncertainty pictured in the hatched bands represents the total (statistical and systematic) uncertainty. The vertical solid, dashed, and dot-dashed lines indicate the edges of the bins in ${x_{\mathrm {r}}}$ and ${m_{\mathrm {r}}}$ and the midpoints of the ${c^{*}}$ distributions, respectively, corresponding to the binning schemes listed in Tables 2-5 in Appendix B. |
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Figure 9-c:
Comparisons of fitted data and MC expectations as a function of template bin number for the ${A^{(1)}_\mathrm {FB}}$ parameter extraction. The plots show events in the type-1 (upper row) and type-2 (lower row) $\mu$+jets (left column) and e+jets (right column) channels, all summed over lepton charge. The MC uncertainty pictured in the hatched bands represents the total (statistical and systematic) uncertainty. The vertical solid, dashed, and dot-dashed lines indicate the edges of the bins in ${x_{\mathrm {r}}}$ and ${m_{\mathrm {r}}}$ and the midpoints of the ${c^{*}}$ distributions, respectively, corresponding to the binning schemes listed in Tables 2-5 in Appendix B. |
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Figure 9-d:
Comparisons of fitted data and MC expectations as a function of template bin number for the ${A^{(1)}_\mathrm {FB}}$ parameter extraction. The plots show events in the type-1 (upper row) and type-2 (lower row) $\mu$+jets (left column) and e+jets (right column) channels, all summed over lepton charge. The MC uncertainty pictured in the hatched bands represents the total (statistical and systematic) uncertainty. The vertical solid, dashed, and dot-dashed lines indicate the edges of the bins in ${x_{\mathrm {r}}}$ and ${m_{\mathrm {r}}}$ and the midpoints of the ${c^{*}}$ distributions, respectively, corresponding to the binning schemes listed in Tables 2-5 in Appendix B. |
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Figure 10:
Comparisons of fitted data and MC expectations as a function of template bin number for the ${A^{(1)}_\mathrm {FB}}$ parameter extraction. The plots show events in the type-3 $\mu$+jets (upper) and e+jets (lower) channels, all summed over lepton charge. The MC uncertainty pictured in the hatched bands represents the total (statistical and systematic) uncertainty. The vertical solid, dashed, and dot-dashed lines indicate the edges of the bins in ${x_{\mathrm {r}}}$ and ${m_{\mathrm {r}}}$ and the midpoints of the ${c^{*}}$ distributions, respectively, corresponding to the binning schemes listed in Tables 6 and 7 in Appendix B. |
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Figure 10-a:
Comparisons of fitted data and MC expectations as a function of template bin number for the ${A^{(1)}_\mathrm {FB}}$ parameter extraction. The plots show events in the type-3 $\mu$+jets (upper) and e+jets (lower) channels, all summed over lepton charge. The MC uncertainty pictured in the hatched bands represents the total (statistical and systematic) uncertainty. The vertical solid, dashed, and dot-dashed lines indicate the edges of the bins in ${x_{\mathrm {r}}}$ and ${m_{\mathrm {r}}}$ and the midpoints of the ${c^{*}}$ distributions, respectively, corresponding to the binning schemes listed in Tables 6 and 7 in Appendix B. |
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Figure 10-b:
Comparisons of fitted data and MC expectations as a function of template bin number for the ${A^{(1)}_\mathrm {FB}}$ parameter extraction. The plots show events in the type-3 $\mu$+jets (upper) and e+jets (lower) channels, all summed over lepton charge. The MC uncertainty pictured in the hatched bands represents the total (statistical and systematic) uncertainty. The vertical solid, dashed, and dot-dashed lines indicate the edges of the bins in ${x_{\mathrm {r}}}$ and ${m_{\mathrm {r}}}$ and the midpoints of the ${c^{*}}$ distributions, respectively, corresponding to the binning schemes listed in Tables 6 and 7 in Appendix B. |
| Tables | |
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Table 1:
List of nuisance parameters considered in fits to data. The "N" stands for "normalization,'' and "S'' for "shape" of the distribution in the "Type" column. The "Size" column lists the absolute value of the associated fractional shifts averaged over all affected template bins. The quantities $R_{\text {QCD}}^{t/C/R}$ indicate that the QCD multijet yield uncertainties are independent in each topology, channel, and region. |
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Table 2:
Template binning in the type-1 $\mu$+jets signal regions (each template has 12 total bins) |
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Table 3:
Template binning in the type-1 e+jets signal regions (each template has 8 total bins) |
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Table 4:
Template binning in the type-2 $\mu$+jets signal regions (each template has 46 total bins) |
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Table 5:
Template binning in the type-2 e+jets signal regions (each template has 6 total bins) |
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Table 6:
Template binning in the type-3 $\mu$+jets signal regions (each template has 222 total bins) |
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Table 7:
Template binning in the type-3 e+jets signal regions (each template has 164 total bins) |
| Summary |
| The linearized parton-level top quark forward-backward asymmetry (${A^{(1)}_\mathrm{FB}}$) and anomalous chromoelectric (${\hat{d}_{\mathrm{t}}}$) and chromomagnetic (${\hat{\mu}_{\mathrm{t}}})$ moments have been measured using LHC proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. Candidate $\mathrm{t\bar{t}}$ events decaying to lepton+jets final states with "resolved" (low-energy) and "boosted" (high-energy) topologies were selected and reconstructed through a kinematic fit of the decay products to $\mathrm{t\bar{t}}$ hypotheses. The parameters were extracted from independent template-based likelihood fits to the data based on differential models of extensions to leading-order tree-level cross sections for quark-antiquark and gluon-gluon initial states, yielding ${A^{(1)}_\mathrm{FB}}=$ 0.048 $^{+0.095}_{-0.087}$(stat) $^{+0.020}_{-0.029}$ (syst), ${\hat{\mu}_{\mathrm{t}}}=-0.024^{+0.013}_{-0.009}$ (stat) $^{+0.016}_{-0.011}$ (syst), and $|{{\hat{d}_{\mathrm{t}}}}| < $ 0.03 at 95% confidence level. |
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