Cross-section Dependent Top Mass Measurement
in Dilepton Channel using Pzttbar
(Kinematic Method)

Tuula Maki1, Jaroslav Antos2,3, Andy Beretvas4,
Yen-Chu Chen2 , Roman Lysak2,3

1) University of Helsinki and Helsinki Institute of Physics
2) Academia Sinica, Taiwan
3) Institute of Experimental Physics, Slovak Academy of Sciences
4) Fermilab

We present a cross-section constraint top quark mass measurement in the dilepton channel.
This measurement is sensitive to the kinematics of the events and observed number
of events. The unconstrained system of dilepton events is solved using the top-antitop
longitudinal momentum, and the top quark mass is reconstructed for each event.
In 1.2 fb-1 of data, we measure the top mass

Mtop=170.7 +4.2-3.9 (stat.) ± 2.6 (syst.) ± 2.4 (theory) GeV/c2

from the 70 events passing the event selection and the mass reconstruction.



Exactly the same per event mass reconstruction and templates as this analysis

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Blessed plots and tables:

all plots and tables are available in two formats: .gif and .eps
Description of tables and plots gif eps
Theoretical ttbar cross-section. eps
Acceptance of b-tagged and non-tagged events. eps
Reconstructed top mass versus input top mass from pseudo-experiments. eps
Residuals from pseudo-experiments. eps
Pull means from pseudo-experiments. eps
Pull widths from pseudo-experiments. eps
The blue, solid band shows the theoretical ttbar cross-section within its uncertainties, the hatched areas mark the dilepton ttbar cross-section and the template top mass measurement using Pzttbar. The red dot with error bars mark the measured top mass using the cross-section dependent template top mass measurement using Pzttbar. eps
Expected statistical error from pseudo-experiments eps
Extracted top mass from the measured cross section:
Mtop=178.3 +10.1-8.0 (stat.) +4.0-6.0 (syst.) GeV/c2
Systematic and theory errors Systematic uncertainties, detailed table
Source &Delta Mtop(GeV/c2)
Luminosity 1.1
Acceptance 0.5
Mass reconstruction probability 0.5
Number of background events 0.9
Jet energy scale 1.5
B-et energy scale 0.9
Lepton energy scale 0.3
MC generator 0.5
ISR 0.3
FSR 0.3
PDF 0.6
B-tagging ET dependence 0.1
Signal MC statistics 0.2
Background MC statistics 0.4
Background template shape 0.3
Total 2.6

Theory uncertainty
Source &Delta Mtop(GeV/c2)
Theoretical ttbar cross-section 2.4
Systematic and theory errors Systematic uncertainties, summary table
Source &Delta Mtop(GeV/c2)
Expected number of events 1.6
Jet and lepton energy scale 1.8
Signal modeling 0.9
Background modeling 0.3
Template statistics 0.4
Total 2.6

Theory uncertainty
Source &Delta Mtop(GeV/c2)
Theoretical ttbar cross-section 2.4

Last modified: Sun July 15 17:49:03 CEST 2007