Z γ Limits on Neutral Anomalous Coupling in ppbar Collisions at √s=1.96 TeV |
We have measured (Z -> l^{+}l^{-})+γ production with central photons using electronic, muonic, and invisible (neutrino) Z decays. The measured cross section for Z+γ where (M_{ll} > 40 GeV/c^{2}) and the photon is central, has E_{Tγ} > 7 GeV, and is separated from both leptons by ΔR > 0.7 is σ_{obs} = 4.6 ± 0.2 (stat) ± 0.3 (syst) ± 0.3 (lum) picobarns. This compares to the next-to-leading-order calculation of σ_{NLO} = 4.5 ± 0.3 pb, so the measured value is consistent with the expected value. The measured cross section for the subset of these events with M_{μμγ} > 100 GeV/c^{2} (predominently Initial-State-Radiation (ISR) events) is σ_{obs} = 1.2 ± 0.1 (stat) ± 0.2 (syst) ± 0.1 (lum) picobarns. The kinematic distributions also agree with the expected shapes.
These data have been used to set limits on neutral anomalous couplings:
Observed | Expected | |
|h_{3}^{Z}| | < 0.050 | < 0.062 ±0.014 |
|h_{4}^{Z}| | < 0.0034 | < 0.0043 ±0.0009 |
|h_{3}^{γ}| | < 0.051 | < 0.064 ±0.014 |
|h_{4}^{γ}| | < 0.0034 | < 0.0043 ±0.0009 |
Lambda_1200_Zgg_h3_ALLC_Likelihood_Rebin | |
Likelihood function for h_{3}^{γ} Z-γ-γ vertex. | |
eps pdf | |
Lambda_1200_ZZg_h3_ALLC_Likelihood_Rebin | |
Likelihood function for h_{3}^{Z;} Z-Z-γ vertex. | |
eps pdf | |
Lambda_1200_Zgg_h4_ALLC_Likelihood_Rebin | |
Likelihood function for h_{4}^{γ} Z-γ-γ vertex. | |
eps pdf | |
Lambda_1200_ZZg_h4_ALLC_Likelihood_Rebin | |
Likelihood function for h_{4}^{Z;} Z-Z-γ vertex. | |
eps pdf |
Limits from electron and muon data only:
Summary of Zγ ( Z to electrons + Z to muons) data including the measured cross section for both the final-state radiation (FSR) and initial-state radiation (ISR):
Summary of Zγ ( Z to electrons + Z to muons) data including the measured cross section for the final-state radiation (FSR) dominated region (three-body mass less than 100 GeV/c^2):
Summary of Zγ ( Z to electrons + Z to muons) data including the measured cross section for the initial-state radiation (ISR) dominated region (three-body mass greater than 100 GeV/c^2):
Et_7GeV_ZeeZmm | |
Photon Et in the Z → ee and the Z → μμ datasets. | |
eps pdf gif | |
Delta_Ra_ZeeZmm | |
Separation (Delta Ra) between leading lepton and photon (Et > 7 GeV) in the Z → ee and the Z → μμ datasets. | |
eps pdf gif | |
Delta_Rb_ZeeZmm | |
Separation (Delta Rb) between non-leading lepton and photon (Et > 7 GeV) in the Z → ee and the Z → μμ datasets. | |
eps pdf gif | |
llgMass10GeV_Zll_log | |
M_{llγ} distribution in the Z → μμ + Z → ee datasets for events with photon Et > 7 GeV. | |
eps pdf gif | |
llgMass10GeV_Zll | |
M_{llγ} distribution in the Z → μμ + Z → ee datasets for events with photon Et > 7 GeV. | |
eps pdf gif | |
MllVsMllg1GeV_Zll | |
M_{ll} - M_{llγ} distribution in the Z → μμ + Z → ee datasets for photons with Et > 7 GeV. | |
eps pdf gif | |
MllVsMllg1GeVMC_Zll | |
M_{ll} - M_{llγ} distribution in the Z → μμ + Z → ee Monte Carlo (Baur) dataset for photons with Et > 7 GeV. | |
eps pdf gif | |
MllVsMllg1GeVBkg | |
Z + jet and γ + fake Z background to the M_{ll} - M_{llγ} distribution in the Z → μμ + Z → ee dataset for photons with Et > 7 GeV. | |
eps pdf gif | |
MllVsMllg1GeVAll | |
Zγ overlaid on Monte Carlo + jet background to the M_{μμ} - M_{μμγ} distribution in the Z → μμ + Z → ee dataset for photons with Et > 7 GeV. | |
eps pdf gif | |
Mll_10GeV_Zmm | |
M_{ll} distribution in the Z → μμ + Z → ee datasets for events with photon Et > 7 GeV. | |
eps pdf gif | |
EleMuon-Lambda_1200_ZZg_h4_ALLC_gammaEt_LogX | |
Photon Et in the Z→ μ^{+}μ^{-} plus Z→ e^{+}e^{-} datasets. The solid blue line is the Standard Model prediction, while the dashed red line is the anomalous coupling prediction for $h_4^Z = 0.0047$. | |
eps pdf gif | |
EleMuon-Lambda_1200_ZZg_h4_ALLC_gammaEt_LogX1 | |
Same plot as above, but with an expanded range on the y-axis to show the Standard Model prediction in the two highest bins. | |
pdf gif |
EleMuon-Lambda_1200_Zgg_h3_ALLC_2DeltaLogLikelihood_Fit | |
Fit for h_{3}^{γ} with the Z→ μ^{+}μ^{-} plus Z→ e^{+}e^{-} datasets. | |
eps pdf gif | |
EleMuon-Lambda_1200_Zgg_h4_ALLC_2DeltaLogLikelihood_Fit | |
Fit for h_{4}^{γ} with the Z→ μ^{+}μ^{-} plus Z→ e^{+}e^{-} datasets. | |
eps pdf gif | |
EleMuon-Lambda_1200_ZZg_h3_ALLC_2DeltaLogLikelihood_Fit | |
Fit for h_{3}^{Z} with the Z→ μ^{+}μ^{-} plus Z→ e^{+}e^{-} datasets. | |
eps pdf gif | |
EleMuon-Lambda_1200_ZZg_h4_ALLC_2DeltaLogLikelihood_Fit | |
Fit for h_{4}^{Z} with the Z→ μ^{+}μ^{-} plus Z→ e^{+}e^{-} datasets. | |
eps pdf gif |
Ele-Lambda_1200_ZZg_h4_ALLC_gammaEt_LogX | |
Photon Et in the Z→ e^{+}e^{-} dataset. The solid blue line is the Standard Model prediction, while the dashed red line is the anomalous coupling prediction for $h_4^Z = 0.0074$. | |
eps pdf gif | |
Ele-Lambda_1200_ZZg_h4_ALLC_gammaEt_LogX1 | |
Same plot as above, but with an expanded range on the y-axis to show the Standard Model prediction in the two highest bins. | |
pdf gif |
Et_7GeV_Zmm | |
Photon Et in the Z → μμ dataset. | |
eps pdf gif | |
Delta_Ra_Zmm | |
Separation (Delta Ra) between leading muon and photon (Et > 7 GeV) in the Z → μμ dataset. | |
eps pdf gif | |
Delta_Rb_Zmm | |
Separation (Delta Rb) between non-leading muon and photon (Et > 7 GeV) in the Z → μμ dataset. | |
eps pdf gif | |
mmgMass10GeV_Zmm | |
M_{μμγ}$ distribution in the Z → μμ dataset for events with photon Et > 7 GeV. | |
eps pdf gif | |
MmumuVsMmumug1GeV_Zmm | |
M_{μμ} - M_{μμγ}$ distribution in the Z → μμ dataset for photons with Et > 7 GeV. | |
eps pdf gif | |
MmumuVsMmumug1GeVMC_Zmm | |
M_{μμ} - M_{μμγ}$ distribution in the Z → μμ Monte Carlo (Baur) dataset for photons with Et > 7 GeV. | |
eps pdf gif | |
MmumuVsMmumug1GeVBkg | |
Z + jet background to the M_{μμ} - M_{μμγ}$ distribution in the Z → μμ dataset for photons with Et > 7 GeV. | |
eps pdf gif | |
MmumuVsMmumug1GeVAll | |
Zγ overlaid on Monte Carlo + jet background to the M_{μμ} - M_{μμγ}$ distribution in the Z → μμ dataset for photons with Et > 7 GeV. | |
eps pdf gif | |
Mmm_10GeV_Zmm | |
M_{μμ}$ distribution in the Z → μμ dataset for events with photon Et > 7 GeV. | |
eps pdf gif |
phoEt_data_log | |
Photon Et in the photon + missing Et dataset. | |
eps pdf |