Measurement of the ttbar Cross Section in the Lepton + Jets Channel Using Event Kinematics and NN
(Update to 760 pb-1)


R.Hughes, K. Lannon,  B. Winer
The Ohio State University

E. Thomson
University of Pennsylvania

  R. Roser
Fermi National Accelerator Laboratory

J. Conway, R. Erbacher
University of California-Davis


CDF public conference note

Final Results for 760 pb-1:


Final Result
Table showing number of events in data, ttbar fraction, and resulting cross section with statistical errors listed first, systematic errors listed second. (PPT)

Final Fits to NN Output Shape:

Fits for a 760 pb-1 data sample follow bellow.  The W-like shapes include the contribution from W+3p, Wbbar+1p, Z->ll (3 flavors), W->tau nu+2p, WW+1p, WZ, single top.  Electrons and muons have been combined for the fits.  The QCD shape is taken from the non-isolated leptons and fixed to 3.7% from our MET v. Isolation calculations.  The ttbar and W-like shapes float in the fits.  Based on apriori sensitivity expectations, our primary result is for the 3 or more jet bin.

W + 3 or More Jet Sample

W + 4 or More Jet Sample
W+ >= 3 jets fit
Fit to the NN-output shape for at least 3 jets, showing shapes of contributing components (EPS)
W+ >= 4 jets fit
Fit to the NN-output shape for at least 4 jets, showing shapes of contributing components (EPS)
Ht Fit Cross Check >= 3 Jets
Cross-check: Fit to the HT shape for at least 3 jets, showing shapes of contributing components (EPS)
Ht Fit Cross Check >= 4 Jets
Cross-check: Fit to the HT shape for at least 4 jets, showing shapes of contributing components (EPS)

Mass Dependence

Mass Dependence
The cross section we quote assumes a top mass of 175 GeV.  The figure above show the dependence of this result on top mass (EPS)

Fit Fractional-Error/Pull-Dist from pseudoexperiments:

The fit Fractional Error distribution and the fit Pull Distribution for 1500 pseudoexperiments is shown bellow. The red arrow indicates the fractional error obtained from fitting the data.

Distribution of Fit Fractional-Error for 1500 pseudo-experiments (EPS).
Distribution of Fit Fractional-Error for 1500 pseudo-experiments(EPS).

Other Plots

Other plots can be found at the website for the previous blessed version of this analysis.
Last modified on 02/13/06 by Kevin Lannon