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Search for Supersymmetric Top Quarks Decaying to a b Quark and a tau Lepton

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We search for pair production of supersymmetryic top quark decaying via R-parity violating coupling to b-quark and a tau lepton. Presented results are also fully applicable to the case of the 3rd generation scalar leptoquark pair production for . This analysis uses 322 pb-1 of data collected by lepton+track triggers and investigates channels with one of the taus decaying into leptonically and another one hadronically. In the primary signal region, we expect 2.26+0.46-0.22 events and we observe two events. With no excess, we set the upper limit on the production cross-section. The lower limit on the stop mass, assuming Br(stop-->tau b) = 100%, is 155 GeV/c2 for our nominal choice of the NLO cross-section for stop pair production. If theoretical  uncertainties due to PDF's and factorisation scale are taken into acount, the limit is 151 GeV/c2.

 

Plots and Tables:

Production and Acceptance:

Leading LO Feynman diagrams for stop pair production. Same diagrams are applicable to the case of leptoquarks pair production. Plot is available in EPS or GIF format.

Full event selection efficiency of this analysis for region A (events passing all cuts and also cuts) for stop pair production followed by stop pair's decay to one leptonic and one hadronic tau and two b-jets. Plot is available in EPS or GIF format.

 

Control and Signal Regions:

If it is not mentioned otherwise, the plots in this section are for electron and muon channels combined, and loose cut YT>80 GeV/c was applied to increase statistics for the control regions.

Number of jets distribution for events passing all selection cuts and also MT<35 GeV/c2 cut. Plot is available in EPS or GIF format.

Number of jets distribution for events passing all selection cuts and also MT<35 GeV/c2 cut. Cut onYT>110 GeV/c was applied. Plot is available in EPS or GIF format.

Distribution of the missing transverse energy in events passing all selection cuts and also njet=0 and MT<35 GeV/c2 cuts (region C). Plot is available in EPS or GIF format.

Tau candidate number of track distribution for events passing all selection cuts and also njet=0 and MT<35 GeV/c2 cuts (region C). Plot is available in EPS or GIF format.

MT distribution for events passing all selection cuts and also njet=0. Plot is available in EPS or GIF format.

YT distribution for events passing all selection cuts and also njet=0 and MT<35 GeV/c2 cuts (region C). Plot is available in EPS or GIF format.

Distribution of the transverse momentum of the leptonic tau candidate in events passing all selection cuts and also njet=0 and MT<35 GeV/c2 cuts. Plot is available in EPS or GIF format.

Distribution of the transverse momentum of the hadronic tau candidate in events passing all selection cuts and also njet=0 and MT<35 GeV/c2 cuts. Plot is available in EPS or GIF format.


Exclusion Plots:

Exclusion limit in the plane of the cross section of stop pair production vs. stop mass:

Observed limit is shown as a red line; expected limit is shown as a band and corresponds to 68% probability; theoretical cross-section (solid blue line) and its uncertainty (dashed blue lines); earlier limit from CDF and LEP search for 3rd generation leptoquarks. Plot is available in EPS or GIF format.

Exclusion limit in the plane of the cross section of 3rd generation leptoquark (LQ3) pair production vs. LQ3 mass:

Observed limit is shown as a red line; expected limit is shown as a band and corresponds to 68% probability; theoretical cross-section (solid blue line) and its uncertainty (dashed blue lines); earlier limit from CDF and LEP search for 3rd generation leptoquarks. Plot is available in EPS or GIF format.

 

 

Kinematical Distributions for Final Events:

The plots in this section are for electron and muon channels combined, and for events passing all selection cuts and also  cuts (primary signal region).

Distribution of the transverse energy, ET, of the first leading jet. Plot is available in EPS or GIF format.

Distribution of the transverse energy, ET, of the second leading jet. Plot is available in EPS or GIF format.

Distribution of the transverse momentum of the leptonic tau candidate. Plot is available in EPS or GIF format.

Distribution of the transverse momentum of the hadronic tau candidate. Plot is available in EPS or GIF format.

Distribution of the missing transverse energy. Plot is available in EPS or GIF format.

Distribution of MT(l,MET), the transverse mass of the leptonic tau visible momentum and transverse missing energy. Plot is available in EPS or GIF format.

Distribution of YT, the scalar sum of transverse missing energy and visible transverse momenta of the two tau candidates. Plot is available in EPS or GIF format.

 
 
Event Displays for Final Events:

Event display for the event passed all selection cuts and also  cuts (primary signal region) in electron channel: run 185594, event 295912.
2D COT and calorimeter plot is available in EPS or GIF format.

Calorimeter lego plot is available in EPS or GIF format.

Event display for the event passed all selection cuts and also  cuts (primary signal region) in muon channel: run  186145, event 3165242.
2D COT and calorimeter plot is available in EPS or GIF format.

Calorimeter lego plot is available in EPS or GIF format.

Page http://www-cdf.fnal.gov/internal/physics/exotic/physics/r2a/00000000.template/index.html was last updated October 6th, 2004 by Stephan Lammel.
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