Z γ Limits on Neutral Anomalous Coupling in 5/fb of ppbar Collisions at √s=1.96 TeV |
We have measured (Z → l^{+}l^{-})+γ production with central photons using electronic and muonicZ decays. We have also studied invisible (Z →νν )+γ using photons and missing transverse energy. A study of potential anomalous couplings between Z's and photons is performed. Limits are placed on the four CP-conserving couplings (h_{3}^{Z},h_{3}^{γ},h_{4}^{Z},h_{4}^{γ}) using 5 fb^{-1} of data. This is the first measurement of its kind in Z → llγ events at CDF since an analysis performed using 1 fb^{-1} of electron candidate data and 2 fb^{-1} of muon candidate data; improvement is witnessed as this is a statistics-limited measurement.
Limits on ATGC using 5/fb of (Z → l^{+}l^{-})+γ and (Z →νν )+γ data.
Limits, (Λ = 1.2 TeV):
Observed | Expected | |
h_{3}^{Z} | [-0.024,0.027] | < 0.029 |
|h_{4}^{Z}| | < 0.0013 | < 0.0015 |
h_{3}^{γ} | < 0.026 | < 0.029 |
h_{4}^{γ} | [-0.0012 , 0.0013] | < 0.0016 |
Observed | Expected | |
h_{3}^{Z} | [-0.020, 0.021 ] | < 0.023 |
h_{4}^{Z} | < 0.0009 | < 0.0010 |
h_{3}^{γ} | [-0.022, 0.020 ] | < 0.023 |
|h_{4}^{γ}| | < 0.0008 | < 0.0010 |
Znunu_controlreg_comp | |
Photon Et distribution, data vs. our prediction, control region. | |
Znunu_signal_comp | |
Photon Et distribution, neutrino data vs. our prediction, signal region. | |
pdf eps | |
SM_expectation | |
Expected photon Et distributions for SM Z + γ (yellow). Expected background is shown as stacked histograms on top of signal. | |
pdf eps |
Observed | Expected | |
h_{3}^{Z} | [-0.034,0.033] | < 0.036 |
h_{4}^{Z} | [-0.0015, 0.0016] | < 0.0017 |
h_{3}^{γ} | [-0.034,0.033] | < 0.036 |
h_{4}^{γ} | [-0.0017, 0.0016] | < 0.0017 |
data_vs_pred | |
Photon Et distribution, data vs. our prediction, control region. | |
data_vs_pred_v2 | |
Photon Et distribution, data vs. our prediction, signal region. | |
pdf eps | |
templates | |
Expected photon Et distributions for SM (black) and for anomalous couplings (red and blue). Expected background is shown as solid histograms. | |
pdf eps | |
template_w_data | |
Expected and measured photon Et distributions for SM (black) and for anomalous couplings (red and blue). Expected background is shown as solid histograms. | |
pdf eps | |
combined_leptons | |
Invariant mass distribution for combined electronic and muonic decays of Z bosons. | |
eps | |
MllVsMllg | |
llγ vs. ll invariant mass distribution for combined electronic and muonic decays of Z bosons. | |
pdf eps |
Observed | Expected | |
h_{3}^{Z} | [-0.024,0.027] | < 0.029 |
|h_{4}^{Z}| | < 0.0013 | < 0.0015 |
h_{3}^{γ} | < 0.026 | < 0.029 |
h_{4}^{γ} | [-0.0012 , 0.0013] | +/- 0.0016 |
Observed | Expected | |
h_{3}^{Z} | [-0.020, 0.021 ] | < 0.007 |
h_{4}^{Z} | < 0.0009 | < 0.0010 |
h_{3}^{γ} | [-0.022, 0.020 ] | < 0.023 |
|h_{4}^{γ}| | < 0.0008 | < 0.0010 |
logli_combo_1200 | |
One-dimensional log-likelihood limit plots showing limits, combination. | |
pdf eps | |
data_2d_1200_combo_Zgg | |
Two-dimensional limit plot, combination. | |
pdf eps | |
data_2d_1200_combo_ZZg | |
Two-dimensional limit plot, combination. | |
pdf eps | |
logli_combo_1500 | |
One-dimensional log-likelihood limit plots showing limits, combination. | |
pdf eps | |
data_2d_1500_combo_Zgg | |
Two-dimensional limit plot, combination. | |
pdf eps | |
data_2d_1500_combo_ZZg | |
Two-dimensional limit plot, combination. | |
pdf eps |