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QCD Meeting October 1, 2004

_.  Polarization Tom Devlin Rutgers/CDF. Strong polarization seen in fixed-target experiments where jet NOT observed. Is it due to the hard collision?. Is it due to fragmentation?. QCD Meeting October 1, 2004. Status and Plans. Three known contributions to dataset:

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QCD Meeting October 1, 2004

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  1. _  Polarization Tom Devlin Rutgers/CDF Strong polarization seen in fixed-target experiments where jet NOT observed. Is it due to the hard collision? Is it due to fragmentation? QCD Meeting October 1, 2004

  2. 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.

  3. Old Distribution Shown Last Time Fit with no Mass Constraint: Assume Daughters are p Subtract  signal, Smooth Remainder (5-bins)

  4. Fits Without and With Mass Constraints Shown Last Time Two Major Improvements In This

  5. Eliminate Decay Vertices Within 8 cm of Primary Interaction

  6. Eliminate e+e- Cut Events with M2(ee)<0.01

  7. Signal-Noise Improved By Large Factor

  8. 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

  9. 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 

  10. Do this for all bins, and for Ks to get Relative Number of , Ks and Background

  11. For Each Bin in Momentum and Lxy Evaluate Fractions of , Ks and 

  12. Restrictions on Angular Distribution

  13. 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.

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