Lxy Monte Carlo Results

1
Lxy Monte Carlo Results

• Generated all Lxy distributions from pure Herwig
  t-tbar Monte Carlo samples.
• Performed study at mt values of 165 GeV, 175 GeV,
  and 185 Gev, using 230 K events.
• Generated full Lxy distributions using ana.cc
  code, then fit data to a gaussian plus
  exponential.
• Generated and fit 650 event samples using full
  samples as pdfs.
• Results showed ltLxygt to have a slightly cleaner
  correlation with mt than the exponential decay
  constant.
• Remains to be seen what effects inclusion of
  backgrounds will have.

2
The Fitting Procedure

• Declared Function of the form,
• c1exp(-c2(x-c3)2) c4exp(-c5x)

• Used this function to fit 165 GeV distribution,
• results shown to the right.

• Fit other two distributions with c2 and c3
  (gaussian parameters), fixed at 165 GeV values.

Mt 165 GeV
3
Full Fitted Lxy Distributions
Results
Mt 165 GeV
Mt 175 GeV
Mt 185 GeV
4
A More Realistic Sample Size

• Used full Lxy histograms as probability
  distribution functions to generate 1,000 pseudo
  experiments for each mt.
• Each pseudo experiment contained 650 Lxy points.
• Used same fitting function as for full samples.

Mt 175 GeV
5
ltLxygt Values

• Plotted ltLxygt for each pseudo experiment.
• Width of the graph represents uncertainty in
  ltLxygt measurement.

Mt 175 GeV
6
Exponential Decay Constant

• Similarly, plotted exponential decay constant
  derived by fitter for each pseudo experiment.
• The RMS of this distribution was larger than
  MINUIT thought it should be.

Mt 175 GeV
7
ltLxygt vs. Decay Constant