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B Mixing Initial State Tag

B Mixing Initial State Tag. Thomas Moore B Mixing Review March 16, 2000. Initial State Tagging. Initial State Tags Polarization Jet Charge Vertex Charge Lepton Charge Kaon Charge Charge Dipole. Current Status. Core components of I.S. tag. No recent modifications.

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B Mixing Initial State Tag

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  1. B Mixing Initial State Tag Thomas Moore B Mixing Review March 16, 2000

  2. Initial State Tagging • Initial State Tags • Polarization • Jet Charge • Vertex Charge • Lepton Charge • Kaon Charge • Charge Dipole

  3. Current Status Core components of I.S. tag. No recent modifications. • Polarization • Jet Charge Pol = ?? Pol+JetQ  = 74.6% Vtx  = 95.7% ZVTOP  80.7% • Lepton • Kaon • VtxQ • Charge Dipole All updated with ZVTOP3  higher efficiency (bb tag: MpT > 2.0 GeV in either hemi.) Opp. Hemi. MpT (GeV)

  4. Vertex Charge • ZVTOP3 vertex in Opposite Hemi. • Attach secondary • tracks by L/D. • Require VtxQ  0. • Parametrize charge purity versus pT added mass. •  = 50.0% •  = 71.1% Abs(VtxQ) = 1 Abs(VtxQ)  2 Plan to include VXD vectors soon...

  5. Lepton Charge • Lepton NN eid > 0.96 • or WgiveMu = 1. • Lepton attached to ZVTOP3 “B” vertex. • 0.4  pT  3.0 GeV • parametrize tag purity versus pT for VtxQ = 0 and VtxQ  0. •  = 9.7% •  = 75.0% Abs(VtxQ) = 0 tag purity Abs(VtxQ)  0 lepton pT (GeV)

  6. Decay Kaons VtxQ = 0 • Select Kaon tracks using • CRID info. • Kaon tracks in ZVTOP3 • “B” or “D” vertices. • Use QK if more than 1 • Kaon. • Parametrize vs largest • Kaon momentum. tag purity VtxQ  0  = 13.5%  = 71.5% Kaon Ptot (GeV)

  7. Charge Dipole • Locate ZVTOP3 “B” and “D” vertices in the Opposite Hemisphere. • MpT > 2.0 GeV • Decay Length > 0 • Q = (QB-QD)  0 • B/D vertex separation • 250 m < BDdist < 1.0 cm • Parametrize vs MpT •  = 30.7% •  = 66.5% QBDdist Qvtx 0 Qvtx = 0 tag purity pT corrected Mass (GeV)

  8. Probability Distributions(for true MC b quarks) VtxQ Leptons Kaons Charge Dipole b quark probability

  9. Combined Results Pol +JetQ “Charged” Pol +JetQ  = 74.6% Charged  = 69.5% Combined  = 76.2% 67.1% of hemispheres have some “charged” tag. Combined Tag Tag correlation has not been considered. b quark probability

  10. Tag Correlation Problem: Many of our tags contain much of the same information  can’t combine tag probability distributions as if they are independent. Current strategy: Plot true b quark fraction in MC versus calculated b probability (Pb). Fit the resulting curve and apply a correction. True b fraction Probably not the most effective technique... Combined b probability Pb

  11. Comparison with pre-ZVTOP3 AP   abs(1-2TagProb)  Correlations have not been considered in charged tag.

  12. Summary and Plans • Initial State tag now updated to run ZVTOP3. • (Vertex  now 95.7% versus 80.7% for ZVTOP) • Each individual tag has been optimized to make better use • of vertex information. • Work has begun on optimizing tag combination. • To Do: • Include VXD vectors. Better vertex charge purity and mass • determination are expected. • Possibly loosen track quality cuts. • Use decay length cut to reduce mixing effects on neutral • vertices? • Data/MC comparisons.

  13. Lepton+Tracks • Standard analysis has not changed since R16 summer • results. • Expected Improvements: • Boost Resolution (D. Dong). • Initial State Tag Purity. • VXD vectors should improve charge resolution and • possibly decay length resolution. • Due to the increased efficiency, a ZVTOP3 based inclusive • lepton analysis has been explored. Results are very • promising but may be too similar to Lepton+D.

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