CDF Logo Z γ Limits on Neutral Anomalous Coupling in ppbar Collisions at √s=1.96 TeV CDF Logo

Contents

Abstract

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 (Mll > 40 GeV/c2) and the photon is central, has E > 7 GeV, and is separated from both leptons by ΔR > 0.7 is σobs = 4.6 ± 0.2 (stat) ± 0.3 (syst) ± 0.3 (lum) picobarns. This compares to the next-to-leading-order calculation of σNLO = 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 Mμμγ > 100 GeV/c2 (predominently Initial-State-Radiation (ISR) events) is σobs = 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
|h3Z| < 0.050 < 0.062 ±0.014
|h4Z| < 0.0034 < 0.0043 ±0.0009
|h3γ| < 0.051 < 0.064 ±0.014
|h4γ| < 0.0034 < 0.0043 ±0.0009

Summary of Results

Electron + Muon + Neutrino Combined Results

Limits:
Lambda_1200_Zgg_h3_ALLC_Likelihood_Rebin Lambda_1200_Zgg_h3_ALLC_Likelihood_Rebin

Likelihood function for h3γ Z-γ-γ vertex.

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Lambda_1200_ZZg_h3_ALLC_Likelihood_Rebin Lambda_1200_ZZg_h3_ALLC_Likelihood_Rebin

Likelihood function for h3Z; Z-Z-γ vertex.

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Lambda_1200_Zgg_h4_ALLC_Likelihood_Rebin Lambda_1200_Zgg_h4_ALLC_Likelihood_Rebin

Likelihood function for h4γ Z-γ-γ vertex.

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Lambda_1200_ZZg_h4_ALLC_Likelihood_Rebin Lambda_1200_ZZg_h4_ALLC_Likelihood_Rebin

Likelihood function for h4Z; Z-Z-γ vertex.

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Combined electron + muon Results

Limits from electron and muon data only:

Limit Table

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):

Limit Table

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):

Limit Table

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):

Limit Table

Et_7GeV_ZeeZmm Et_7GeV_ZeeZmm

Photon Et in the Z → ee and the Z → μμ datasets.

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Delta_Ra_ZeeZmm Delta_Ra_ZeeZmm

Separation (Delta Ra) between leading lepton and photon (Et > 7 GeV) in the Z → ee and the Z → μμ datasets.

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Delta_Rb_ZeeZmm Delta_Rb_ZeeZmm

Separation (Delta Rb) between non-leading lepton and photon (Et > 7 GeV) in the Z → ee and the Z → μμ datasets.

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llgMass10GeV_Zll_log llgMass10GeV_Zll_log

Mllγ distribution in the Z → μμ + Z → ee datasets for events with photon Et > 7 GeV.

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llgMass10GeV_Zll llgMass10GeV_Zll

Mllγ distribution in the Z → μμ + Z → ee datasets for events with photon Et > 7 GeV.

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MllVsMllg1GeV_Zll MllVsMllg1GeV_Zll

Mll - Mllγ distribution in the Z → μμ + Z → ee datasets for photons with Et > 7 GeV.

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MllVsMllg1GeVMC_Zll MllVsMllg1GeVMC_Zll

Mll - Mllγ distribution in the Z → μμ + Z → ee Monte Carlo (Baur) dataset for photons with Et > 7 GeV.

eps pdf gif
MllVsMllg1GeVBkg MllVsMllg1GeVBkg

Z + jet and γ + fake Z background to the Mll - Mllγ distribution in the Z → μμ + Z → ee dataset for photons with Et > 7 GeV.

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MllVsMllg1GeVAll MllVsMllg1GeVAll

Zγ overlaid on Monte Carlo + jet background to the Mμμ - Mμμγ distribution in the Z → μμ + Z → ee dataset for photons with Et > 7 GeV.

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Mll_10GeV_Zmm Mll_10GeV_Zmm

Mll distribution in the Z → μμ + Z → ee datasets for events with photon Et > 7 GeV.

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EleMuon-Lambda_1200_ZZg_h4_ALLC_gammaEt_LogX 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 $h_4^Z = 0.0047$.

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EleMuon-Lambda_1200_ZZg_h4_ALLC_gammaEt_LogX1 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

These electron + muon data have been used to set limits on neutral anomalous couplings:

Limit Table

EleMuon-Lambda_1200_Zgg_h3_ALLC_2DeltaLogLikelihood_Fit EleMuon-Lambda_1200_Zgg_h3_ALLC_2DeltaLogLikelihood_Fit

Fit for h3γ with the Z→ μ+μ- plus Z→ e+e- datasets.

eps pdf gif
EleMuon-Lambda_1200_Zgg_h4_ALLC_2DeltaLogLikelihood_Fit EleMuon-Lambda_1200_Zgg_h4_ALLC_2DeltaLogLikelihood_Fit

Fit for h4γ with the Z→ μ+μ- plus Z→ e+e- datasets.

eps pdf gif
EleMuon-Lambda_1200_ZZg_h3_ALLC_2DeltaLogLikelihood_Fit EleMuon-Lambda_1200_ZZg_h3_ALLC_2DeltaLogLikelihood_Fit

Fit for h3Z with the Z→ μ+μ- plus Z→ e+e- datasets.

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EleMuon-Lambda_1200_ZZg_h4_ALLC_2DeltaLogLikelihood_Fit EleMuon-Lambda_1200_ZZg_h4_ALLC_2DeltaLogLikelihood_Fit

Fit for h4Z with the Z→ μ+μ- plus Z→ e+e- datasets.

eps pdf gif

Zγ, Z decaying to e+e- (1 fb-1)

Ele-Lambda_1200_ZZg_h4_ALLC_gammaEt_LogX 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 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

These electron data have been used to set limits on neutral anomalous couplings:

Limit Table

Zγ, Z decaying to μ+μ-(2 fb-1)

Et_7GeV_Zmm Et_7GeV_Zmm

Photon Et in the Z → μμ dataset.

eps pdf gif
Delta_Ra_Zmm 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 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 mmgMass10GeV_Zmm

Mμμγ$ distribution in the Z → μμ dataset for events with photon Et > 7 GeV.

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MmumuVsMmumug1GeV_Zmm MmumuVsMmumug1GeV_Zmm

Mμμ - Mμμγ$ distribution in the Z → μμ dataset for photons with Et > 7 GeV.

eps pdf gif
MmumuVsMmumug1GeVMC_Zmm MmumuVsMmumug1GeVMC_Zmm

Mμμ - Mμμγ$ distribution in the Z → μμ Monte Carlo (Baur) dataset for photons with Et > 7 GeV.

eps pdf gif
MmumuVsMmumug1GeVBkg MmumuVsMmumug1GeVBkg

Z + jet background to the Mμμ - Mμμγ$ distribution in the Z → μμ dataset for photons with Et > 7 GeV.

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MmumuVsMmumug1GeVAll MmumuVsMmumug1GeVAll

Zγ overlaid on Monte Carlo + jet background to the Mμμ - Mμμγ$ distribution in the Z → μμ dataset for photons with Et > 7 GeV.

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Mmm_10GeV_Zmm Mmm_10GeV_Zmm

Mμμ$ distribution in the Z → μμ dataset for events with photon Et > 7 GeV.

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These muon data have been used to set limits on neutral anomalous couplings:

Limit Table

Zγ, Z decaying to νν

phoEt_data_log phoEt_data_log

Photon Et in the photon + missing Et dataset.

eps pdf


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