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| CMS-SMP-18-002 ; CERN-EP-2018-322 | ||
| Measurements of the ${{\mathrm{p}}{\mathrm{p}}\to\mathrm{W}\mathrm{Z}}$ inclusive and differential production cross section and constraints on charged anomalous triple gauge couplings at ${\sqrt{s}} = $ 13 TeV | ||
| CMS Collaboration | ||
| 10 January 2019 | ||
| JHEP 04 (2019) 122 | ||
| Abstract: The WZ production cross section is measured in proton-proton collisions at a centre-of-mass energy ${\sqrt{s}} = $ 13 TeV using data collected with the CMS detector, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. The inclusive cross section is measured to be ${\sigma_{\text{tot}}}({{\mathrm{p}}{\mathrm{p}}\to\mathrm{W}\mathrm{Z}}) = $ 48.09 $^{+1.00}_{-0.96}$ (stat) $^{+0.44}_{-0.37}$ (theo) $^{+2.39}_{-2.17}$ (syst) $\pm$ 1.39 (lumi) pb, resulting in a total uncertainty of $-2.78/+2.98$ pb. Fiducial cross section and charge asymmetry measurements are provided. Differential cross section measurements are also presented with respect to three variables: the Z boson transverse momentum ${p_{\mathrm{T}}}$, the leading jet ${p_{\mathrm{T}}}$, and the ${m({\mathrm{W}\mathrm{Z}} )}$ variable, defined as the invariant mass of the system composed of the three leptons and the missing transverse momentum. Differential measurements with respect to the W boson $ {p_{\mathrm{T}}}$, separated by charge, are also shown. Results are consistent with standard model predictions, favouring next-to-next-to-leading-order predictions over those at next-to-leading order. Constraints on anomalous triple gauge couplings are derived via a binned maximum likelihood fit to the ${m({\mathrm{W}\mathrm{Z}} )}$ variable. | ||
| Links: e-print arXiv:1901.03428 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; HepData record ; CADI line (restricted) ; | ||
| Figures | |
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Figure 1:
Feynman diagrams for WZ production at leading order in perturbative QCD in proton-proton collisions for the $s$-channel (left), $t$-channel (middle), and $u$-channel (right). The contribution from $s$-channel proceeds through TGC. |
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Figure 1-a:
Feynman diagram for WZ production at leading order in perturbative QCD in proton-proton collisions for the $s$-channel. The contribution from $s$-channel proceeds through TGC. |
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Figure 1-b:
Feynman diagram for WZ production at leading order in perturbative QCD in proton-proton collisions for the $t$-channel. Figure 1-c |
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Figure 1-c:
Feynman diagrams for WZ production at leading order in perturbative QCD in proton-proton collisions for the $s$-channel (left), $t$-channel (middle), and $u$-channel (right). The contribution from $s$-channel proceeds through TGC. |
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Figure 2:
Distribution of key observables in the signal region: invariant mass of the lepton pair assigned to the Z boson (top left), invariant mass of the three-lepton system (top right), missing transverse momentum (bottom left), and transverse momentum of the leading lepton assigned to the W boson. For each distribution all the signal region requirements are applied except the requirement relating to the particular observable so that the effect of the requirement on that observable can be easily seen. The last bin contains the overflow. Vertical bars on the data points include the statistical uncertainty and shaded bands over the prediction include the contributions of the different sources of uncertainty at their values after the signal extraction fit. |
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Figure 2-a:
Distribution of the invariant mass of the lepton pair assigned to the Z boson in the signal region. The last bin contains the overflow. Vertical bars on the data points include the statistical uncertainty and shaded bands over the prediction include the contributions of the different sources of uncertainty at their values after the signal extraction fit. |
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Figure 2-b:
Distribution of the invariant mass of the three-lepton system in the signal region. The last bin contains the overflow. Vertical bars on the data points include the statistical uncertainty and shaded bands over the prediction include the contributions of the different sources of uncertainty at their values after the signal extraction fit. |
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Figure 2-c:
Distribution of the missing transverse momentum in the signal region. The last bin contains the overflow. Vertical bars on the data points include the statistical uncertainty and shaded bands over the prediction include the contributions of the different sources of uncertainty at their values after the signal extraction fit. |
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Figure 2-d:
Distribution of the transverse momentum of the leading lepton assigned to the W boson in the signal region. The last bin contains the overflow. Vertical bars on the data points include the statistical uncertainty and shaded bands over the prediction include the contributions of the different sources of uncertainty at their values after the signal extraction fit. |
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Figure 3:
Distribution of key observables in the ZZ control region defined in Table 1: flavour composition of the three leading leptons (top left), invariant mass of the three leptons plus missing transverse momentum (top right), transverse momentum of the W boson reconstructed from the $ {p_{\mathrm {T}}} $ of the two leptons assigned to it (bottom left), and transverse momentum of the leading jet (bottom right). Vertical bars on the data points include the statistical uncertainty and shaded bands over the prediction include the contributions of the different sources of uncertainty evaluated after the signal extraction fit. |
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Figure 3-a:
Distribution of the flavour composition of the three leading leptons in the ZZ control region defined in Table 1. Vertical bars on the data points include the statistical uncertainty and shaded bands over the prediction include the contributions of the different sources of uncertainty evaluated after the signal extraction fit. |
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Figure 3-b:
Distribution of the invariant mass of the three leptons plus missing transverse momentum in the ZZ control region defined in Table 1. Vertical bars on the data points include the statistical uncertainty and shaded bands over the prediction include the contributions of the different sources of uncertainty evaluated after the signal extraction fit. |
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Figure 3-c:
Distribution of the transverse momentum of the W boson reconstructed from the $ {p_{\mathrm {T}}} $ of the two leptons assigned to it in the ZZ control region defined in Table 1. Vertical bars on the data points include the statistical uncertainty and shaded bands over the prediction include the contributions of the different sources of uncertainty evaluated after the signal extraction fit. |
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Figure 3-d:
Distribution of the transverse momentum of the leading jet in the ZZ control region defined in Table 1. Vertical bars on the data points include the statistical uncertainty and shaded bands over the prediction include the contributions of the different sources of uncertainty evaluated after the signal extraction fit. |
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Figure 4:
Distribution of key observables in the top enriched control region defined in Table 1: flavour composition of the three leading leptons (top left), invariant mass of the three lepton plus missing transverse momentum (top right), transverse momentum of the Z boson reconstructed from the ${p_{\mathrm {T}}}$ of the two leptons assigned to it (bottom left), and transverse momentum of the leading jet (bottom right). Vertical bars on the data points include the statistical uncertainty and shaded bands over the prediction include the contributions of the different sources of uncertainty evaluated after the signal extraction fit. |
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Figure 4-a:
Distribution flavour composition of the three leading leptons in the top enriched control region defined in Table 1. Vertical bars on the data points include the statistical uncertainty and shaded bands over the prediction include the contributions of the different sources of uncertainty evaluated after the signal extraction fit. |
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Figure 4-b:
Distribution invariant mass of the three lepton plus missing transverse momentum in the top enriched control region defined in Table 1. Vertical bars on the data points include the statistical uncertainty and shaded bands over the prediction include the contributions of the different sources of uncertainty evaluated after the signal extraction fit. |
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Figure 4-c:
Distribution transverse momentum of the Z boson reconstructed from the $ {p_{\mathrm {T}}} $ of the two leptons assigned to it in the top enriched control region defined in Table 1. Vertical bars on the data points include the statistical uncertainty and shaded bands over the prediction include the contributions of the different sources of uncertainty evaluated after the signal extraction fit. |
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Figure 4-d:
Distribution transverse momentum of the leading jet in the top enriched control region defined in Table 1. Vertical bars on the data points include the statistical uncertainty and shaded bands over the prediction include the contributions of the different sources of uncertainty evaluated after the signal extraction fit. |
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Figure 5:
Distribution of key observables in the conversion control region defined in Table 1: flavour composition of the three leading leptons (top left), invariant mass of the three lepton plus missing transverse momentum (top right), transverse momentum of the Z boson reconstructed from the $ {p_{\mathrm {T}}} $ of the two leptons assigned to it (bottom left), and transverse momentum of the leading jet (bottom right). Vertical bars on the data points include the statistical uncertainty and shaded bands over the prediction include the contributions of the different sources of uncertainty evaluated after the signal extraction fit. |
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Figure 5-a:
Distribution of the flavour composition of the three leading leptons in the conversion control region defined in Table 1. Vertical bars on the data points include the statistical uncertainty and shaded bands over the prediction include the contributions of the different sources of uncertainty evaluated after the signal extraction fit. |
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Figure 5-b:
Distribution of the invariant mass of the three lepton plus missing transverse momentum in the conversion control region defined in Table 1. Vertical bars on the data points include the statistical uncertainty and shaded bands over the prediction include the contributions of the different sources of uncertainty evaluated after the signal extraction fit. |
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Figure 5-c:
Distribution of the transverse momentum of the Z boson reconstructed from the $ {p_{\mathrm {T}}} $ of the two leptons assigned to it in the conversion control region defined in Table 1. Vertical bars on the data points include the statistical uncertainty and shaded bands over the prediction include the contributions of the different sources of uncertainty evaluated after the signal extraction fit. |
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Figure 5-d:
Distribution of the transverse momentum of the leading jet in the conversion control region defined in Table 1. Vertical bars on the data points include the statistical uncertainty and shaded bands over the prediction include the contributions of the different sources of uncertainty evaluated after the signal extraction fit. |
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Figure 6:
Distribution of expected and observed event yields in the four flavour categories used for the cross section measurement. Vertical bars on the data points include the statistical uncertainty and shaded bands over the prediction include the contributions of the different sources of uncertainty evaluated after the signal extraction fit. |
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Figure 7:
Measured ratio of cross sections for the two charge channels for each of the flavour categories and their combination. Values are normalized to the NLO prediction obtained with POWHEG. Coloured bands for each of the points include both systematic and statistical uncertainties. Shaded bands correspond to the MC prediction from the nominal POWHEG sample and its associated uncertainty. |
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Figure 8:
Prefit distributions of key observables in the signal region. The transverse momentum of the Z boson (top left), the transverse momentum of the leading jet (top right), and the mass of the WZ system (bottom). The last bin contains the overflow. Vertical bars on the data points include the statistical uncertainty and the shaded band over the MC prediction include both the statistical and the systematic uncertainties in the normalization of each of the background processes. An additional 15% uncertainty is assigned to the signal WZ process in the figures to account for the NLO/NNLO normalization differences. |
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Figure 8-a:
Prefit distribution of the transverse momentum of the Z boson in the signal region. The last bin contains the overflow. Vertical bars on the data points include the statistical uncertainty and the shaded band over the MC prediction include both the statistical and the systematic uncertainties in the normalization of each of the background processes. An additional 15% uncertainty is assigned to the signal WZ process to account for the NLO/NNLO normalization differences. |
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Figure 8-b:
Prefit distribution of the transverse momentum of the leading jet in the signal region. The last bin contains the overflow. Vertical bars on the data points include the statistical uncertainty and the shaded band over the MC prediction include both the statistical and the systematic uncertainties in the normalization of each of the background processes. An additional 15% uncertainty is assigned to the signal WZ process to account for the NLO/NNLO normalization differences. |
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Figure 8-c:
Prefit distribution of the mass of the WZ system in the signal region. The last bin contains the overflow. Vertical bars on the data points include the statistical uncertainty and the shaded band over the MC prediction include both the statistical and the systematic uncertainties in the normalization of each of the background processes. An additional 15% uncertainty is assigned to the signal WZ process to account for the NLO/NNLO normalization differences. |
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Figure 9:
Response matrices obtained using NLO samples, simulated with the POWHEG generator. The transverse momentum of the Z boson (top left), the leading jet transverse momentum (top right) and the mass of the WZ system (bottom) are shown. |
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Figure 9-a:
Response matrice for the transverse momentum of the Z boson, obtained using NLO samples simulated with the POWHEG generator. |
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Figure 9-b:
Response matrice for the leading jet transverse momentum (top right) and the mass of the WZ system, obtained using NLO samples simulated with the POWHEG generator. |
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Figure 9-c:
Response matrices obtained using NLO samples, simulated with the POWHEG generator. The transverse momentum of the Z boson (top left), the leading jet transverse momentum (top right) and the mass of the WZ system (bottom) are shown. |
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Figure 10:
Differential distributions for the Z boson $ {p_{\mathrm {T}}} $ (top left), leading jet $ {p_{\mathrm {T}}} $ (top right), and mass of the WZ system (bottom). Data distributions are unfolded at the dressed leptons level and compared with the POWHEG, MadGraph 5_aMC@NLO NLO generators, and PYTHIA predictions, as described in the text. The red band around the POWHEG prediction represents the theory uncertainty in it; the effect on the unfolded data of this uncertainty, through the unfolding matrix, is included in the shaded bands described in the legend. |
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Figure 10-a:
Differential distribution for the Z boson $ {p_{\mathrm {T}}} $. The data distribution is unfolded at the dressed leptons level and compared with the POWHEG, MadGraph 5_aMC@NLO NLO generators, and PYTHIA predictions, as described in the text. The red band around the POWHEG prediction represents the theory uncertainty in it; the effect on the unfolded data of this uncertainty, through the unfolding matrix, is included in the shaded bands described in the legend. |
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Figure 10-b:
Differential distribution for the leading jet $ {p_{\mathrm {T}}} $. The data distribution is unfolded at the dressed leptons level and compared with the POWHEG, MadGraph 5_aMC@NLO NLO generators, and PYTHIA predictions, as described in the text. The red band around the POWHEG prediction represents the theory uncertainty in it; the effect on the unfolded data of this uncertainty, through the unfolding matrix, is included in the shaded bands described in the legend. |
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Figure 10-c:
Differential distribution for the mass of the WZ system. The data distribution is unfolded at the dressed leptons level and compared with the POWHEG, MadGraph 5_aMC@NLO NLO generators, and PYTHIA predictions, as described in the text. The red band around the POWHEG prediction represents the theory uncertainty in it; the effect on the unfolded data of this uncertainty, through the unfolding matrix, is included in the shaded bands described in the legend. |
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Figure 11:
Differential distributions for W$^{+}$ (left) and W$^{-}$ (right), in the full SR. The leading jet transverse momentum is unfolded at the dressed leptons level, as described in the text. The red band around the POWHEG prediction represents the theory uncertainty in it. The effect on the unfolded data of this uncertainty, through the unfolding matrix, is included in the shaded bands described in the legend. |
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Figure 11-a:
Differential distribution for W$^{+}$, in the full SR. The leading jet transverse momentum is unfolded at the dressed leptons level, as described in the text. The red band around the POWHEG prediction represents the theory uncertainty in it. The effect on the unfolded data of this uncertainty, through the unfolding matrix, is included in the shaded bands described in the legend. |
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Figure 11-b:
Differential distribution for W$^{-}$, in the full SR. The leading jet transverse momentum is unfolded at the dressed leptons level, as described in the text. The red band around the POWHEG prediction represents the theory uncertainty in it. The effect on the unfolded data of this uncertainty, through the unfolding matrix, is included in the shaded bands described in the legend. |
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Figure 12:
Differential distributions for W$^{+}$ (left) and W$^{-}$ (right), in the full SR. The transverse momentum of the Z boson is unfolded at the dressed leptons level, as described in the text. The red band around the POWHEG prediction represents the theory uncertainty in it; the effect on the unfolded data of this uncertainty, through the unfolding matrix, is included in the shaded bands described in the legend. |
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Figure 12-a:
Differential distribution for W$^{+}$, in the full SR. The transverse momentum of the Z boson is unfolded at the dressed leptons level, as described in the text. The red band around the POWHEG prediction represents the theory uncertainty in it; the effect on the unfolded data of this uncertainty, through the unfolding matrix, is included in the shaded bands described in the legend. |
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Figure 12-b:
Differential distribution for W$^{-}$, in the full SR. The transverse momentum of the Z boson is unfolded at the dressed leptons level, as described in the text. The red band around the POWHEG prediction represents the theory uncertainty in it; the effect on the unfolded data of this uncertainty, through the unfolding matrix, is included in the shaded bands described in the legend. |
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Figure 13:
Differential distributions for W$^{+}$ (left) and W$^{-}$ (right), in the full SR. The mass of the WZ system data distribution is unfolded at the dressed leptons level, as described in the text. The red band around the POWHEG prediction represents the theory uncertainty in it; the effect on the unfolded data of this uncertainty, through the unfolding matrix, is included in the shaded bands described in the legend. |
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Figure 13-a:
Differential distribution for W$^{+}$, in the full SR. The mass of the WZ system data distribution is unfolded at the dressed leptons level, as described in the text. The red band around the POWHEG prediction represents the theory uncertainty in it; the effect on the unfolded data of this uncertainty, through the unfolding matrix, is included in the shaded bands described in the legend. |
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Figure 13-b:
Differential distribution for W$^{-}$, in the full SR. The mass of the WZ system data distribution is unfolded at the dressed leptons level, as described in the text. The red band around the POWHEG prediction represents the theory uncertainty in it; the effect on the unfolded data of this uncertainty, through the unfolding matrix, is included in the shaded bands described in the legend. |
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Figure 14:
Differential distributions for W$^{+}$ (left) and W$^{-}$ (right), in the full SR. The W boson transverse momentum is unfolded at the dressed leptons level, as described in the text. The red band around the POWHEG prediction represents the theory uncertainty in it; the effect on the unfolded data of this uncertainty, through the unfolding matrix, is included in the shaded bands described in the legend. |
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Figure 14-a:
Differential distribution for W$^{+}$, in the full SR. The W boson transverse momentum is unfolded at the dressed leptons level, as described in the text. The red band around the POWHEG prediction represents the theory uncertainty in it; the effect on the unfolded data of this uncertainty, through the unfolding matrix, is included in the shaded bands described in the legend. |
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Figure 14-b:
Differential distribution for W$^{-}$, in the full SR. The W boson transverse momentum is unfolded at the dressed leptons level, as described in the text. The red band around the POWHEG prediction represents the theory uncertainty in it; the effect on the unfolded data of this uncertainty, through the unfolding matrix, is included in the shaded bands described in the legend. |
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Figure 15:
Distributions of discriminant observables in the anomalous triple gauge couplings searches. The invariant mass of the three lepton and missing transverse momentum system (left) and the transverse mass of the same configuration (right). The dashed lines represent the total yields expected from the sum of the SM processes, with the total WZ yields for different values of the associated anomalous coupling (AC) parameters. The SM prediction for the WZ process is obtained from the aTGC simulated sample with the AC parameters set to 0. |
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Figure 15-a:
Distribution of the invariant mass of the three lepton and missing transverse momentum system in the anomalous triple gauge couplings searches. The dashed lines represent the total yields expected from the sum of the SM processes, with the total WZ yields for different values of the associated anomalous coupling (AC) parameters. The SM prediction for the WZ process is obtained from the aTGC simulated sample with the AC parameters set to 0. |
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Figure 15-b:
Distribution of the transverse mass of the same configuration in the anomalous triple gauge couplings searches. The dashed lines represent the total yields expected from the sum of the SM processes, with the total WZ yields for different values of the associated anomalous coupling (AC) parameters. The SM prediction for the WZ process is obtained from the aTGC simulated sample with the AC parameters set to 0. |
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Figure 16:
Two-dimensional confidence regions for each of the possible combinations of the considered aTGC parameters. The contours of the expected confidence regions for 68% and 95% confidence level are presented in each case. The parameters considered in each plot are ${c_{{\mathrm {W}}}} - {c_{{\mathrm {W}} {\mathrm {W}} {\mathrm {W}}}}$ (top), ${c_{{\mathrm {W}}}} - {c_{{\mathrm {b}}}}$ (middle) and ${c_{{\mathrm {W}} {\mathrm {W}} {\mathrm {W}}}} - {c_{{\mathrm {b}}}}$ (bottom). |
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Figure 16-a:
Two-dimensional confidence region of the ${c_{{\mathrm {W}}}} - {c_{{\mathrm {W}} {\mathrm {W}} {\mathrm {W}}}}$ combination of the aTGC parameters. The contours of the expected confidence regions for 68% and 95% confidence level are presented in each case. |
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Figure 16-b:
Two-dimensional confidence region of the ${c_{{\mathrm {W}}}} - {c_{{\mathrm {b}}}}$ combination of the aTGC parameters. The contours of the expected confidence regions for 68% and 95% confidence level are presented in each case. |
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Figure 16-c:
Two-dimensional confidence region of the ${c_{{\mathrm {W}} {\mathrm {W}} {\mathrm {W}}}} - {c_{{\mathrm {b}}}}$ combination of the aTGC parameters. The contours of the expected confidence regions for 68% and 95% confidence level are presented in each case. |
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Figure 17:
Evolution of the expected and observed confidence intervals of the EFT anomalous coupling parameters in terms of the cutoff scale given by different restrictions in the ${m({{\mathrm {W}} {\mathrm {Z}}})}$ variable. For each point and parameter, the confidence intervals are computed imposing the additional restriction of no anomalous coupling contribution over the given value of the ${m({{\mathrm {W}} {\mathrm {Z}}})}$ cutoff. The last point is equivalent to no cutoff requirement being imposed. The parameters considered are: ${c_{{\mathrm {W}}}}$ (top), ${c_{{\mathrm {W}} {\mathrm {W}} {\mathrm {W}}}}$ (middle) and ${c_{{\mathrm {b}}}}$ (bottom). |
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Figure 17-a:
Evolution of the expected and observed confidence intervals of the ${c_{{\mathrm {W}}}}$ anomalous coupling parameter in terms of the cutoff scale given by different restrictions in the ${m({{\mathrm {W}} {\mathrm {Z}}})}$ variable. For each point and parameter, the confidence intervals are computed imposing the additional restriction of no anomalous coupling contribution over the given value of the ${m({{\mathrm {W}} {\mathrm {Z}}})}$ cutoff. The last point is equivalent to no cutoff requirement being imposed. |
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Figure 17-b:
Evolution of the expected and observed confidence intervals of the ${c_{{\mathrm {W}} {\mathrm {W}} {\mathrm {W}}}}$ anomalous coupling parameter in terms of the cutoff scale given by different restrictions in the ${m({{\mathrm {W}} {\mathrm {Z}}})}$ variable. For each point and parameter, the confidence intervals are computed imposing the additional restriction of no anomalous coupling contribution over the given value of the ${m({{\mathrm {W}} {\mathrm {Z}}})}$ cutoff. The last point is equivalent to no cutoff requirement being imposed. |
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Figure 17-c:
Evolution of the expected and observed confidence intervals of the ${c_{{\mathrm {b}}}}$ anomalous coupling parameter in terms of the cutoff scale given by different restrictions in the ${m({{\mathrm {W}} {\mathrm {Z}}})}$ variable. For each point and parameter, the confidence intervals are computed imposing the additional restriction of no anomalous coupling contribution over the given value of the ${m({{\mathrm {W}} {\mathrm {Z}}})}$ cutoff. The last point is equivalent to no cutoff requirement being imposed. |
| Tables | |
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Table 1:
Requirements for the definition of the signal region of the analysis and the three different regions designed to estimate the main background sources. |
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Table 2:
Expected and observed yields for each of the relevant processes and flavour categories. Combined statistical and systematic uncertainties are shown for each case except for the observed data yields for which only statistical uncertainties are presented. All expected yields correspond to quantities estimated after the maximum likelihood fit. Uncertainties are computed taking into account the full correlation matrix between sources of uncertainty, processes, and flavour categories. |
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Table 3:
Summary of the total postfit impact of each uncertainty source on the uncertainty in the signal strength measurement, for the four flavour categories and their combination. Theoretical uncertainties are only included in the signal acceptance during the extrapolation to the total phase space, so they are not included in the likelihood fit. The values are percentages and correspond to half the difference between the up and down variation of each systematic uncertainty component. |
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Table 4:
Measured fiducial cross sections and their corresponding uncertainties for each of the individual flavour categories, as well as for the combination of the four. |
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Table 5:
Measured WZ production cross sections computed separately in each of the flavour categories. |
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Table 6:
Differential cross section in bins of $ {p_{\mathrm {T}}} $ (Z). Values are expressed as fraction of the total cross section. The eee and ee$\mu$ final states are shown. |
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Table 7:
Differential cross section in bins of $ {p_{\mathrm {T}}} $ (Z). Values are expressed as fraction of the total cross section. The e${{\mu}} {{\mu}}$ and $ {{\mu}} {{\mu}} {{\mu}}$ final states are shown. |
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Table 8:
Differential cross section in bins of $ {p_{\mathrm {T}}} $ (Z). Values are expressed as fraction of the total cross section. The inclusive final state is shown |
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Table 9:
Differential cross section in bins of $ {p_{\mathrm {T}}} $ (Leading jet). Values are expressed as fraction of the total cross section. The eee, ee${{\mu}}$, e${{\mu}} {{\mu}}$, and ${{\mu}} {{\mu}} {{\mu}}$ final states are shown. |
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Table 10:
Differential cross section in bins of $ {p_{\mathrm {T}}} $ (Leading jet). Values are expressed as fraction of the total cross section. The inclusive final state is shown. |
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Table 11:
Differential cross section in bins of mass of the WZ system. Values are expressed as fraction of the total cross section. |
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Table 12:
Expected and observed one-dimensional confidence intervals (CI) at 95% confidence level for each of the considered EFT parameters. |
| Summary |
|
The production process ${{\mathrm{p}}{\mathrm{p}}\to\mathrm{W}\mathrm{Z}}$ is studied in the trilepton final state at ${\sqrt{s}} = $ 13 TeV, using the full 2016 data set with a total integrated luminosity of 35.9 fb$^{-1}$ collected with the CMS detector. Fiducial results are obtained in each of the flavour categories (eee, ee$\mu$, e$\mu\mu$, and $\mu\mu\mu$) and in the combined category, and are extrapolated to the total WZ production cross section for 60 $ < {m_{\mathrm{Z}}} ^{OSSF} < $ 120 GeV. The combined measurement yields a cross section of ${\sigma_{\text{tot}}}({\mathrm{p}}{\mathrm{p}} \to {\mathrm{W}\mathrm{Z}} ) = $ 48.09 $^{+1.00}_{-0.96}$ (stat) $^{+0.44}_{-0.37}$ (theo) $^{+2.39}_{-2.17}$ (syst) $\pm$ 1.39 (lumi) pb, for a total uncertainty of $+2.98$ and $-2.78$ pb. The result is in good agreement with the MATRIX next-to-next-to-leading-order (NNLO) prediction [56] of $\sigma_{\mathrm{NNLO}}({\mathrm{p}}{\mathrm{p}} \to {\mathrm{W}\mathrm{Z}} ) = $ 49.98 ($+$2.2%)($-$2.0%) pb. This result supersedes the result from the CMS Collaboration using data corresponding to a smaller integrated luminosity of 2.3 fb$^{-1}$ [14]. A measurement in the fiducial region yields a value of $\sigma_{\text{fid}}({\mathrm{p}}{\mathrm{p}} \to {\mathrm{W}\mathrm{Z}} ) = $ 257.5 $^{+5.3}_{-5.0}$ (stat) $^{+2.3}_{-2.0}$ (theo) $^{+12.8}_{-11.6}$ (syst) $\pm$ 7.4 (lumi) fb, pointing to an excess over the POWHEG next-to-leading-order cross section $\sigma_{\text{fid}}^{POWHEG} = $ 227.6 $^{+9.4}_{-8.0}$ fb. The cross sections are also measured independently for the two possible values of the W boson charge, yielding a ratio of ${A^{+-}_{{\mathrm{W}\mathrm{Z}} }} = {\sigma_{\text{tot}}}({\mathrm{p}}{\mathrm{p}} \to \mathrm{W}^+\mathrm{Z})/{\sigma_{\text{tot}}}({\mathrm{p}}{\mathrm{p}} \to \mathrm{W}^-\mathrm{Z}) = $ 1.48 $\pm$ 0.06, which is compatible within uncertainties with the POWHEG + PYTHIA prediction of 1.43$^{+0.06}_{-0.05}$. Similar results are obtained when splitting by flavour category. All the measurements of this paper are compatible with the SM when the appropriate order of theoretical calculations is considered. Differential cross sections are measured as a function of the transverse momentum of the Z boson, of the transverse momentum of the leading jet, and of an estimate of the mass of the WZ system; results are compared with predictions from the POWHEG and MadGraph5+MCatNLO generators. Differential cross sections as a function of the transverse momentum of the leading jet are also measured for each sign of the W boson charge. Confidence intervals for anomalous triple gauge boson couplings are extracted for each of the possible one- and two-dimensional combinations of the anomalous couplings parameters, using the ${m({\mathrm{W}\mathrm{Z}} )}$ variable in a maximum likelihood fit. The confidence intervals obtained represent the most stringent results on the anomalous $\mathrm{W{\mathrm{W}\mathrm{Z}}} $ triple gauge coupling to date. |
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