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Bs  DsK Continued

Bs  DsK Continued. Introduction. B s D s - K + provides access to the sum of CKM angle g+f s . f s from B s J/ yf  determine g Will be a statistically limited measurement. Expect ~7K untagged events with D s KK p 2 fb -1  s g ~13 o From B - D 0 K - , expect s g ~5-10 o

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Bs  DsK Continued

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  1. Bs  DsKContinued

  2. Introduction • BsDs-K+ provides access to the sum of CKM angle g+fs. fs from BsJ/yf  determine g • Will be a statistically limited measurement. • Expect ~7K untagged events with DsKKp • 2 fb-1  sg ~13o • From B-D0K- , expect sg ~5-10o • Would like to aim for comparable resolution on these two measurements • Need to look at other modes in time-dependent measurement using Bs

  3. Other Ds Decays • B(DsKKp) ~ 5.5% • Can get ~33% more stats using: • Dsppp (1.1%) • DsKpp (0.7%) • DsKsK (BF~1.5%) suffers from low efficiency & poor resolution on Bs decay vertex position. • DsKKpp0 (~5.7%) likely suffers from large combinatorics and low efficiency for p0.

  4. Other modes, from the W+ • In BsDsK+, W+ hadronizes into a K+. • It could also hadronize into K*+, but • Have to deal with either Ksp+ or K+p0 final state  • Should be investigated though • Could hadronize into K1(1270)+ • (Sheldon’s suggestion from last time) • BsDs K1(1270)+ • BF? Trigger? Recon eff? • K1(1270)+  K+p-p+ (~1/3 of time)

  5. Summary of Cut Comparison

  6. Cross-check on BsDsK • Same cuts as Limingshowed on 5/21/08. • - Except proton PID cut • Rec + Sel Efficiency: • = 616 / 13919 = (4.4±0.2)% Identical efficiency toLiming.

  7. BsDsK1 (1270)+ • Rec + Sel Efficiency: • = 329 / 20000 = (1.6±0.1)% Clean… Not matchedto MC Bs

  8. >4 Bs <4 <4 eL0~45% for BsDsK <0.9997 eL0~48%

  9. 1947-1989 MeV Ds >3 <4 >1.0 GeV

  10. 1170-1370 MeV K1 Not matchedto MC K1 >3 <5 >1.0 GeV

  11. Summary e ~ 0.70% with K1, Dsppp & DsKpp, compared to 0.38% with KKp only 85% increase compared to default BsDsK analysis!

  12. Other prospectsBsDs*K Ignore the photon from Ds*Dsg (will check into situation if we try to include the photon) Need to cut hard on bach kaon PID, to reject Ds*p (BsDs*p peaks at same location) If we know the shapes & background contribution, we can use these events. Average correction for photon momentum  ~small degradation in proper time BsDs*p BsDs*X (from Liming) back DsK signal

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