Search for Lepton-Photon Events at CDF

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, 305 pb-1, a ppbar collision energy of 1.96 TeV, and the upgraded CDF II detector. We find 42 Lepton+Photon+MET events versus a standard model expectation of 37.3 +- 5.4 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 Multi-Lepton+Photon+X we observe 31 events versus an expectation of 23.0 +- 2.7 events. In this sample we find no events with an extra photon or MET and so find no events like the one ee+gg+MET event observed in Run I.

• Contacts: Andrei Loginov and Henry Frisch
• Data: Run II, 305 pb^-1
• Documentation (Public note):
  The paper has been submitted to PRL and available at hep-ex 0605097,
  CDF Note 8187 (PRL Draft, final version) PS
• Proceedings (Lepton-Photon-X Search is one of the analyses presented at SUSY 2005 Conference and Erice School of Subnuclear Physics):
  PS, PDF

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 PS or PDF, or JPG,
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. PS or PDF, or JPG,
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 3-body invariant mass of Leptons + Photon, and d) the 2-body mass of the dilepton system. The histograms show the expected SM contributions. PS or PDF, or JPG,
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. PS or PDF, or JPG,
Lepton-Photon Sample Flow Chart
	Lepton-Photon Sample: the subsets of inclusive Lepton+Photon events analyzed. PS or PDF, or JPG,
Muon-Photon Sample Flow Chart
	Muon-Photon Sample: the subsets of inclusive Muon+Photon events analyzed. PS or PDF, or JPG,
Electron-Photon Sample Flow Chart
	Electron-Photon Sample: the subsets of inclusive Electron+Photon events analyzed. PS or PDF, or JPG,
Summary table
	A comparison of the numbers of events predicted by the Standard Model and the observations for the Lepton+Photon+Missing Transverse Energy and Multiple Leptons + Photon searches. The SM predictions for the two searches are dominated by W+gamma and Z+gamma production, respectively. 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. PS or PDF, or JPG,