Top Quark Mass Measurement in the 2.8 fb ^-1 Tight Lepton and Isolated Track Sample using Neutrino &Phi Weighting Method

We present the top quark mass measurement in the tight lepton and isolated track sample using neutrino &Phi weighting method. The unconstrained system of dilepton events is solved using the hypothesis about neutrino phi values. In 2.8 fb^-1 of data, we measure the top mass

M_top=165.1 ^+3.3_-3.2 (stat.) ± 3.1 (syst.) GeV/c²

from the 330 events passing the event selection.

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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
Two-component, constrained fit to the l+trk selected top mass candidates. The violet solid area corresponds to the background returned by the fit and the blue solid area is the sum of background and signal events. The insert shows the mass-dependent negative log-likelihood used in the fit. Measured top mass from 330 data events: Mtop=15.1 +3.3-3.2 (stat.) ± 3.1 (syst.) GeV/c2		eps
Expected statistical errors from pseudo-experiments.The arrows indicate the errors returned by the fit to the data.		eps
The examples of the signal templates for masses in the region 159-189 GeV/c2.		eps
Templates of background processes Drell-Yan, Diboson, "fake" events. Lower right plot shows the combined background.		eps
The extracted top mass as a function of input mass. The result of a linear fit is also shown. The lower plot shows the residuals (reconstructed - input top mass).		eps
Mean (above) and &sigma (below) of pull distributions determined from the pseudo-experiments as a function of input top mass.		eps
Systematic errors.	Systematic uncertainties Source &Delta Mtop(GeV/c2) Jet energy scale 2.9 b-Jet Energy Scale 0.4 Pileup 0.2 Initial and Final State Radiations 0.3 Parton Distribution Functions 0.3 Monte-Carlo Generators 0.2 Background composition 0.5 Faked shape 0.4 Drell-Yan shape 0.3 Lepton Energy Scale 0.3 Total 3.1
We also performed the unconstrained fit to the l+trk selected top mass candidates. The violet solid area corresponds to the background returned by the fit and the blue solid area is the sum of background and signal events. The insert shows the mass-dependent negative log-likelihood used in the fit. The fit returns the top mass Mtop=165.0+3.3-3.2 GeV/c2 with 118.2+27.5-25.5 background events.		eps

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Data validation plots (tight lepton and isolated track events):

Missing Et distribution for 2 jet events.		eps
Pt lepton distribution for 2 jet events.		eps
&Delta &Phi between missing Et and highest Et jet distribution for 2 jet events.		eps
Two lepton invariant mass distrubution for 2 jet events.		eps
Et leading jet distribution for 2 jet events.		eps
&Delta &Phi between Missing Et and second leading jet distribution for 2 jet events.		eps
&Delta &Phi between Missing Et and tight lepton distribution for 2 jet events.		eps
&Delta &Phi between Missing Et and isolated track distribution for 2 jet events.		eps
&Delta R between tight lepton and isolated track distribution for 2 jet events.		eps
&Delta R between tight lepton and leading jet distribution for 2 jet events.		eps
&Delta R between tight lepton and second leading jet distribution for 2 jet events.		eps
&Delta R between isolated track and leading jet distribution for 2 jet events.		eps
&Delta R between isolated track and second leading jet distribution for 2 jet events.		eps
Missing Et distribution for 0 jet events.		eps
Missing Et distribution for 1 jet events.		eps
Pt lepton distribution for 0 jet events.		eps
Pt lepton distribution for 1 jet events.		eps
Dilepton invariant mass distribution for 0 jet events.		eps
Dilepton invariant mass distribution for 1 jet events.		eps
Predicted vs observed number of events with different jet numbers.		eps

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    by Marco Trovato