Search for New Physics in Di-Electron Events

Search for New Physics in Di-Electron Events, Internal Page

This Run II analysis searches for new physics in high mass di-electron events which would produce an excess over the Standard Model. The search is optimized for a narrow resonance but still retains sensitivity to other excesses, with the sensitivity decreasing as the width of the excess increases. The search is otherwise model independent. No evidence of new physics is observed.

Seperately the analysis also sets limits on specific models for spin-1 and spin-2 particles. The analysis sets a limit on cross-section x branching ratio for spin-1 and spin-2 particles and then translates this into an exclusion limit on the masses of the SM-like Z', the E6 Z's and the RS Graviton. The RS Graviton limits are then further improved by combining with the di-photon analysis.

This analysis represents a continuation of the previous analysis with 820 pb^-1 and the only major changes are the addition of 500 pb^-1 of new data (up to Sept 2006) and updates to the latest and greatest Monte Carlo samples.

Authors: Joel Goldstein, Sam Harper and Peter Renton (University of Oxford)
Blessed: Jan 25, 2007
Godparents: Fabio Happacher, Kaori Maeshima, Larry Nodulman
Data: Run II, 1288 pb^-1
Documentation:
CDF note 8671 Main Analysis Note for 1288 pb^-1 update (summarizes the analysis)
CDF note 8062 Main Analysis Note for 820 pb^-1 (more complete description)
CDF note 8385 Describes the combination with di-photon channel
CDF note 7527 Optimizing selection cuts
Public: Note 8694 PS, PDF, and Web Page

Blessed Plots and Tables:

High Mass Total Selection Efficiency:
spin-1 : GIF, EPS
spin-2 : GIF, EPS
Mass Spectrum Plots :
Di-Electron mass spectrum (5 GeV binning):
central-central: GIF, EPS
central-plug: GIF, EPS
central-central + central-plug: GIF, EPS
Di-Electron mass spectrum (Varible binning):
central-central: GIF, EPS
central-plug: GIF, EPS
central-central + central-plug: GIF, EPS
Integral of the di-electron mass spectrum:
central-central: GIF, EPS
central-plug: GIF, EPS
central-central + central-plug: GIF, EPS
Anti-Conversion: this is the mass spectrum of central-plug events which pass all cuts as normal except that the central electron is required to fail the conversion cut rather than pass it. This is a good cross-check of the background estimate but would not normally be shown at conferences unless you were trying to convince your audience that we really do have the backgrounds under control. GIF, EPS
Signal Search:
P-value Plot : GIF, EPS
Speakers: even if you dont show this plot, I strongly recommend you have it in your backup slides because you might well get the question, so is there anything there at 250 GeV? This plot allows everybody to see how their favourite mass point, be it 250 or 330 or whatever is doing.
Limits :
spin-1 (Z'): GIF, EPS
spin-2 (RS Graviton) : GIF, EPS
Expected Limits :
spin-1 :
central-central GIF, EPS
central-plug GIF, EPS
central-central + central-plug GIF, EPS
spin-2 :
central-central GIF, EPS
central-plug GIF, EPS
central-central + central-plug GIF, EPS

High Mass Events :
high mass CC (run 220182, event 14888605) COT, CAL

high mass CP (run 207079, event 8749310) COT, CAL

Combined limits with the di-photon channel :
cross-section limits GIF, EPS

k/Mpl vs mass limits GIF, EPS

Mass Limits Z':

Z' Model Z'_{SM} Z'_{ETA} Z'_{CHI} Z'_{PSI} Z'_{IOTA}

Mass Limit (GeV/c^2) 923 891 822 822 729

Mass Limits RS Graviton (GeV/c^2):

k/Mpl 0.01 0.025 0.05 0.07 0.10

e+e- 302 469 674 741 807

gamma gamma 230 500 694 782 850

e+e- + gamma gamma 267 580 761 820 889

Page was last updated Febuary 6th, 2007 by Sam Harper.
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High Mass Total Selection Efficiency:
	spin-1 : GIF, EPS spin-2 : GIF, EPS
Mass Spectrum Plots :
	Di-Electron mass spectrum (5 GeV binning): central-central: GIF, EPS central-plug: GIF, EPS central-central + central-plug: GIF, EPS
	Di-Electron mass spectrum (Varible binning): central-central: GIF, EPS central-plug: GIF, EPS central-central + central-plug: GIF, EPS
	Integral of the di-electron mass spectrum: central-central: GIF, EPS central-plug: GIF, EPS central-central + central-plug: GIF, EPS
	Anti-Conversion: this is the mass spectrum of central-plug events which pass all cuts as normal except that the central electron is required to fail the conversion cut rather than pass it. This is a good cross-check of the background estimate but would not normally be shown at conferences unless you were trying to convince your audience that we really do have the backgrounds under control. GIF, EPS
Signal Search:
	P-value Plot : GIF, EPS Speakers: even if you dont show this plot, I strongly recommend you have it in your backup slides because you might well get the question, so is there anything there at 250 GeV? This plot allows everybody to see how their favourite mass point, be it 250 or 330 or whatever is doing.
Limits :
	spin-1 (Z'): GIF, EPS spin-2 (RS Graviton) : GIF, EPS
Expected Limits :
	spin-1 : central-central GIF, EPS central-plug GIF, EPS central-central + central-plug GIF, EPS
	spin-2 : central-central GIF, EPS central-plug GIF, EPS central-central + central-plug GIF, EPS
High Mass Events :
	high mass CC (run 220182, event 14888605) COT, CAL
	high mass CP (run 207079, event 8749310) COT, CAL
Combined limits with the di-photon channel :
	cross-section limits GIF, EPS
	k/Mpl vs mass limits GIF, EPS

Z' Model	Z'_{SM}	Z'_{ETA}	Z'_{CHI}	Z'_{PSI}	Z'_{IOTA}
Mass Limit (GeV/c^2)	923	891	822	822	729

k/Mpl	0.01	0.025	0.05	0.07	0.10
e+e-	302	469	674	741	807
gamma gamma	230	500	694	782	850
e+e- + gamma gamma	267	580	761	820	889