CDF Logo Search for Lepton-Photon Events at CDF Public Page Exotics Logo

We present results of a search for anomalous production of events containing a charged lepton (either electron or muon) and a photon, both with high transverse momentum, accompanied by additional signatures, X, including missing transverse energy (MET) and additional leptons and photons. We use the same kinematic selection criteria as in a previous CDF search, but with a substantially larger data set, 929 pb-1, a ppbar collision energy of 1.96 TeV, and the upgraded CDF II detector. We find 163 Lepton+Photon+MET events versus a standard model expectation of 150.6 +- 13.0 events. The level of excess observed in Run I, 16 events with an expectation of 7.6 +- 0.7 events (corresponding to a 2.7 sigma effect), is not supported by the new data. In the signature of (ee/&mu&mu)+Photon+X we observe 74 events versus an expectation of 65.1 +- 7.7 events. In this sample we find no events with an extra photon and so find no events like the one ee+&gamma&gamma+MET event observed in Run I. In the signature of Electron+Muon+Photon+X we find no events versus an expectation of 1.0 +- 0.3 events. In the signature of Multi-Photon+Lepton+X we find no events versus an expectation of 0.62 +- 0.15 events.



Blessed Plots and Tables (PS are intended for latex presentations, PDF for PowerPoint/pdflatex):

Selection Cuts for Lepton + Photon + X
The Selection Cuts for Lepton+Photon+X. The kinematic selection is set a priori - it is the same as criteria used in the previous Run I CDF search (hep-ex/0202044), and the same as used in recent CDF Run II publication on 305 pb-1(hep-ex/0605097)
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Lepton + Photon + Missing Transverse Energy Plots
The distributions for events in the Lepton+Photon+Missing Transverse Energy sample (points) in a) the E_T of the photon; b) the E_T of the lepton, c) the Missing Transverse Energy, and d) the transverse mass of the Lepton+Photon-Missing Transverse Energy system. The histograms show the expected SM contributions, including estimated backgrounds from misidentified photons and leptons. We find 163 Lepton+Photon+MET events versus a standard model expectation of 150.6 +- 13.0 events. The level of excess observed in Run I, 16 events with an expectation of 7.6 +- 0.7 events (corresponding to a 2.7 sigma effect), is not supported by the new data.
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Multi-Lepton + Photon Plots
The distributions for events in the Multiple Leptons + Photon sample (points) in a) the E_T of the photon; b) the E_T of the lepton, c) the 2-body mass of the dilepton system, and d) the 3-body invariant mass of Leptons + Photon. The histograms show the expected SM contributions. In the signature of Multi-Lepton + Photon + X we observe 74 events versus an expectation of 65.1 +- 7.7 events. In this sample we find no events with an extra photon and so find no events like the one ee+gg+MET event observed in Run I.
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Multi-Lepton + Photon Plots: missing transverse energy
The distributions in Missing Transverse Energy, observed in the Multiple Leptons + Photon inclusive search for muon pairs (Left) and electron pairs (Right). The histograms show the expected SM contributions. In the Multi-Lepton + Photon + X with MET > 25 GeV 3 events observed are consistent with the SM expectation of 0.6 +- 0.1 events.
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Lepton+Photon+MET Summary table
A comparison of the numbers of events predicted by the Standard Model and the observations for the Lepton+Photon+Missing Transverse Energy search. The SM predictions for the search are dominated by W+gamma and Z+gamma production. Other contributions come from the tri-boson processes W+gamma+gamma and Z+gamma+gamma, leptonic tau decays, and misidentified leptons, photons, or Missing Transverse Energy.
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Multi-Lepton + Photon Summary table
A comparison of the numbers of events predicted by the Standard Model and the observations for the Multiple Leptons + Photon search. The SM predictions for the search are dominated by Z+gamma production. Other contributions come from the Z+gamma+gamma, and misidentified leptons and photons.
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Electron+Muon+Photon Summary table
A comparison of the numbers of events predicted by the Standard Model and the observations for the Electron+Muon+Photon search. The SM predictions for the search are dominated by Z+gamma production. Other contributions come from the W+gamma, Z+gamma+gamma, W+gamma+gamma, and misidentified leptons and photons.
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Multi-Photon + Lepton Summary table
A comparison of the numbers of events predicted by the Standard Model and the observations for the Multiple Photons + Lepton search. Dominant contribution comes from misidentified photons. The SM predictions are dominated by Z+gamma+gamma production.
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Additional Plots for Lepton+Photon+MET Search
Lepton+Photon+MET. The distributions for events in a) H_T, the sum of the transverse energies of the lepton, photon, jets and MET; b) the distance in eta-phi space between the photon and lepton; c) the angular separation in phi between the lepton and MET; and d) the invariant mass of the Lepton+Photon system.
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Additional Plots for Lepton+Photon+MET Search in the Muon channel
Muon+Photon+MET. The distributions for events in in a) the E_T of the photon; b) the P_T of the muon; c) the missing transverse energy; and d) the transverse mass of the Muon+Photon+MET.
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Muon+Photon+MET. The distributions for events in a) H_T, the sum of the transverse energies of the muon, photon, jets and MET; b) the distance in eta-phi space between the photon and muon; c) the angular separation in phi between the muon and MET; and d) the invariant mass of the Muon+Photon system.
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Additional Plots for Lepton+Photon+MET Search in the Electron channel
Electron+Photon+MET. The distributions for events in in a) the E_T of the photon; b) the E_T of the electron; c) the missing transverse energy; and d) the transverse mass of the Electron+Photon+MET.
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Electron+Photon+MET. The distributions for events in a) H_T, the sum of the transverse energies of the electron, photon, jets and MET; b) the distance in eta-phi space between the photon and electron; c) the angular separation in phi between the electron and MET; and d) the invariant mass of the Electron+Photon system.
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Additional Plots for Multi-Lepton + Photon Search
Multi-Lepton + Photon. The distributions for events in a) H_T, the sum of the transverse energies of the lepton, photon, jets and MET; b) the distance in eta-phi space between the photon and each of the two leptons.
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Additional Plots for Multi-Lepton + Photon Search: Muon Channel
Muon+Photon+MET. The distributions for events in a) the E_T of the photon; b) the P_T of the muon, c) the 2-body mass of the dimuon system, and d) the 3-body invariant mass of Muons + Photon.
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Multi-Muon + Photon. The distributions for events in a) H_T, the sum of the transverse energies of the muon, photon, jets and MET; b) the distance in eta-phi space between the photon and each of the two muons.
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Additional Plots for Multi-Lepton + Photon Search: Electron Channel
Electron+Photon+MET. The distributions for events in a) the E_T of the photon; b) the E_T of the electron, c) the 2-body mass of the dielectron system, and d) the 3-body invariant mass of Electrons + Photon.
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Multi-Electron + Photon. The distributions for events in a) H_T, the sum of the transverse energies of the electron, photon, jets and MET; b) the distance in eta-phi space between the photon and each of the two electrons.
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Summary slide
Lepton+Photon+X summary slide
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