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Exploring the CKM Angle g through Bs → DsK Decays: Statistical Measurements and Prospects

This study focuses on the decay process Bs → DsK+, which provides access to the CKM angle g. The analysis expects approximately 7,000 untagged events with a statistical limit on measuring g with a resolution similar to Bs → D0K−. The potential for higher statistics through other decay modes such as Ds → ppp and Ds → Kpp is examined. Various hadronization possibilities and potential background issues are discussed, along with efficiencies and cut comparisons for improved measurements. This research aims to refine the understanding of flavor physics through Bs decays.

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Exploring the CKM Angle g through Bs → DsK Decays: Statistical Measurements and Prospects

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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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