QCD Meeting

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QCD Meeting October 1, 2004
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Status and Plans
Three known contributions to dataset -- ?
Signal -- Ks Background -- Continuum 2-track
background MC code exists to generate first
two. Coding in progress for the third. Plan
Generate 20 MC of each type for each real event.
Mix three MC samples, in appropriate
proportions to produce 20 MC events for
each real event. Adjust proportions of each
and assumed polarization of MC ?s to fit
data.
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Old Distribution Shown Last Time Fit with no Mass
Constraint Assume Daughters are p? Subtract ?
signal, Smooth Remainder (5-bins)
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Fits Without and With Mass Constraints Shown Last
Time
Two Major Improvements In This
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Eliminate Decay Vertices Within 8 cm of Primary
Interaction
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Eliminate ??ee- Cut Events with M2(ee)lt0.01
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Signal-Noise Improved By Large Factor
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Huge Improvement in Signal/Noise Extended
Momentum Range from 2-12 GeV/c to 2-20
GeV/c Study ?, Ks, ?? Background vs. Momentum and
Flight Distance Lxy
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For one bin in p and Lxy (loose-cut ?)
(tight-cut ?), (tight-cut Ks), plot both vs.
M2(p?) Sum of two plots Ks background Subtract
from loose-cut ? ? Number of pure ?
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Do this for all bins, and for Ks to get Relative
Number of ?, Ks and Background
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For Each Bin in Momentum and Lxy Evaluate
Fractions of ?, Ks and ??
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Restrictions on Angular Distribution
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Work in Progress and Planned Fall, 2004

• ? Mass-constrained fits 2-?, 2-Ks, 1-ee.
• ? Sum of weights over solutions 1.0 per event.
• ? Use ??2 ?2(MassConstraint) -
  ?2(NoMassConstraint)
• ? Determine relative proportions of ?, Ks and
  background
• Modify 2nd stage analysis code to mix MC samples
  from
• ?, Ks, ?? in correct proportions.
• Possibly as fit parameters with
  constraints.
• See if a believable polarization analysis can be
  done
• in one of the three coordinate systems.
• If so, do polarization in the other two
  coordinate systems.