Systematic Uncertainties

Contents

  1. JES
  2. Jet Resolution
  3. ISR
  4. FSR
  5. Generators & Lepton Filter
  6. Background Statistics
  7. Background Shape
  8. Parton Distribution Functions
  9. b-tagging
  10. b-jet energy scale
  11. Monte Carlo Statistics
  12. ***** Top Mass *****
  13. Acceptance Ratio for mass2tag_nochi and mass1tag4_nochi
  14. Various Statistics

Table of the means of the width distributions

Input Top Width Mean(JES = -1) (GeV) Mean(JES = 0) (GeV) Mean(JES = +1) (GeV)
1.5 GeV 0.27 1.90 5.69
5 GeV 3.57 5.71 9.32
15 GeV 12.12 12.57 17.73
30 GeV 24.58 26.67 31.04
50 GeV 36.3 38.98 42.48
Input Top Width Mean(JES = -1) - Mean(JES = 0) (GeV) Mean(JES = +1) - Mean(JES = 0) (GeV)
1.5 GeV -1.63 3.79
5 GeV -2.14 3.61
15 GeV -0.45 5.16
30 GeV -2.09 4.37
50 GeV -2.68 3.50

JES shifts for Gamma = 1.5 GeV

JES is varied from -2.0 to +2.0 with 0.5 spacing.
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Convolution for input top width 1.5 GeV

The black function is the convoluted width function. (width function * Probability vs Shifts of the width) The red function is the original fitted width function.
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  • Jet Resolution
  • Pt-dependent extra smearing. Amount of extra smearing is calculated using the following equation: smearing = 0.02878 + 1.704/Pt (cdfNote 7856). Since input top width = 15 GeV gives us the largest shifts in the mean of measured top width distribution, we use 2.836 GeV as the jet resolution systematic and convolute in Feldman-Cousins.
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  • ISR
  • Histograms are listed from the left to right: ISR less, default, ISR more
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    Mean - Meandefault (GeV)
    Less ISR -0.69
    More ISR -0.64

  • FSR
  • Histograms are listed from the left to right: FSR less, default, FSR more
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    Mean - Meandefault (GeV)
    Less FSR -0.61
    More FSR -0.87

    Overlay

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  • Generator & Lepton Filter
  • Generator

    Pythia on the left Herwig on the right. Mtop = 175 GeV/c2.
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    Lepton Filter

    With lepton filter and without lepton filter. Mtop = 175 GeV/c2. Gamma = 1.5 GeV.
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    Mean - Meandefault (GeV)
    Lepton Filter -0.46

    Overlay

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  • Background Statistics
  • Left: Half background events, Center: default background events, Right: Twice background events
    Comparing the PEs without gaussian background constraint.
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    Mean - Meandefault (GeV)
    x1/2 Bkgd events -1.23
    x2 Bkgd events 1.87

    Overlay

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  • Background Shape
  • Left: Half background events, Center: default background events, Right: Twice background events
    Comparing the PEs without gaussian background constraint.
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    Background Shape Mean - Meanfull bkgd (GeV)
    Wbb2P 0.029
    W4P -0.26
    Single Top (t-channel) -0.98
    Single Top (s-channel) -0.31

    Overlay

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  • Parton Distribution Functions
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  • b-Jet Energy Scale
  • Shift of mean of the distributions vs extra jet energy factor for various input top width.
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  • MC statistics
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  • Top Mass
  • Dependency on Top Mass

    Top Mass will not be incorporated to the systematic uncertainties, but just to study how our PEs change with different top mass.
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    Overlay

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  • Acceptance Ratio
  • Acceptance Ratio for 2-tag sample is calculated by (# of events that are in mass2tag_nochi)/(# of events that passed the good run requirements). Similarly for 1-tagT sample (labeled as 1-tag).
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  • Studying width dependency on the ISR and FSR systematic
  • Because the shape of the width shifts vs ISR syst (or FSR syst) is not known, we tested linear and second order polynomial fit.
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    The left CL bands are assuming the second order polynomial functional form for ISR and FSR systematics. The right CL bands are assuming the linear functinal form for ISR and FSR systematics. Second order polyomials gives us higher limit on the top width than the linera fit. So being conservative, we chose the second order polynomial fit to ISR and FSR systematics.
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    These are results for limit setting PEs using confidence bands with systematic uncertainties. Left is the results of PEs using input top widht 1.5 GeV samples and right is the result of PEs using input top width of 30 GeV. The results look what we expect. (higher top width limit on the average)
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  • Various Luminosity
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