Precision Lifetime Measurements of B Mesons at the Tevatron

1. B Physics at the Tevatron IILifetimes and DG Ronald Lipton, Fermilab For the CDF and D0 collaborations • New results for Moriond 2005 • Lifetimes in semileptonic decays • B0,B+ (CDF) • Bs (D0) • Lifetimes in Hadronic decays (CDF) • DG Bs (D0) Ronald Lipton, Moriond EW2005

2. Lifetime Measurements • Collider experiments are beginning to provide precision measurements of Bs, Lb, Bc , B0, B- lifetimes • Verify HQET predictions • Input to other measurements • Try to measure ratios to minimize systematics • Pre-Moriond results: CDF D0 Ronald Lipton, Moriond EW2005

3. Lifetime Fits • Unbinned maximum likelihood components • Signal lifetime • Background lifetimes • Background fractions • B mass peak (signal fraction) • Momentum resolution, for each decay mode and type j, Kj • ct resolution scale factor, s • Typically ~15 parameters • Likelihood functions: Ronald Lipton, Moriond EW2005

4. CDF Semileptonic B0, B- • Uses electron and muon triggers ~260 pb-1 • No trigger lifetime bias • Different semileptonic branching ratios of B0, B- into D,D*- allows extraction of the two lifetimes and their ratios Ronald Lipton, Moriond EW2005

5. CDF Semleptonic Lifetimes Mostly B0 Mostly B- Ronald Lipton, Moriond EW2005

6. Semileptonic Bs • Bs→DsmnX • Large data sample from muon triggers ~400 pb-1 • Take K distribution from several semileptonic modes, B0,B- • Include charm backgrounds in the fit (wide tails) Ronald Lipton, Moriond EW2005

7. CDF Hadronic modes • First lifetime results to use events triggered by SVT (silicon vertex trigger) • ~360 pb-1 • Impact parameter biases lifetime distributions but provides large samples • Correct for trigger bias using Monte Carlo – verify with B- • Systematics ~ 4-5 mm • Five modes: Ronald Lipton, Moriond EW2005

8. Hadronic Lifetimes 5.3 5.5 0.3 Ronald Lipton, Moriond EW2005

9. Lifetime values Ronald Lipton, Moriond EW2005

10. Summary of new lifetime results Ronald Lipton, Moriond EW2005

11. Bs System Schrodinger Equation: M12 stems from the real part of the box diagram, dominated by topG12 stems from the imaginary part, dominated by charm Heavy and light Bs eigenstates are expected to have different widths Ronald Lipton, Moriond EW2005

12. DG Bs • Relation of matrix elements to decay and oscillation parameters: In the Standard Model: • The CP violating phase, f is expected to be small • Mass eigenstates are ~CP eigenstates with definite lifetimes • The J/y f final state is a mixture of CP statesL=0,2 – CP even (A0,A||)L=1 – CP odd (A┴) • Assuming no CP violation in the Bs system, measure two Bs lifetimes,tLandtH, (orDG/Gand t) by simultaneously fitting time evolution and angular distribution in untagged Bs J/y f decays • CDF result last summer: Ronald Lipton, Moriond EW2005

13. Transversity Analysis  =transversity Full angular distribution Sensitivity to CP violation if  / is sizable Detector acceptance Ronald Lipton, Moriond EW2005

14. DG B -> J/yf D0 Preliminary • CDF summer result fit to q,f,yangles giving A0, A||, A ┴, phase, R ┴ =|A ┴(0)|2 • New D0 result integrates over the angles f,y using MC efficiency • Fit technique similar to lifetime fit, but adds angle dependence • Provides values for t, DG, and R ┴- no amplitudes or phase 483±32 Integral for flat Efficiency in f,y Ronald Lipton, Moriond EW2005

15. Likelihood Fit • Simultaneous fit to mass, proper decay length and transversity using an unbinned maximum log-likelihood method 1 fsig signal fraction 1 c =c/ ,  = (L+ H)/2 1 R CP-odd fraction at t=0 1  / Other free parameters 2 signal mass, width 2 bkg mass slope (1 prompt, 1 long-lived) 1 (c ) scale 6 bkg c shape 4 bkg transversity (2 prompt +2 long-lived) ------ 19 total Ronald Lipton, Moriond EW2005

16. DG Result D0 Preliminary • Fit Result: D0 Preliminary D0 Preliminary Ronald Lipton, Moriond EW2005

17. Additional Constraints D0 Preliminary • Include tfs constraint from semleptonic measurements: • We can also use the predicted value of DGcp cons. =0.12±0.05 (Lenz hep-ph/0412007) with the semileptonic constraint to constrain a possible CP phase: Ronald Lipton, Moriond EW2005

18. DG Comparisons • D0 and CDF DG/G results are consistent • D0 result is close to the theory prediction of 0.12±0.05 • The WA flavor specific lifetime provides significant improvement to DG and allows for a meaningful cosf constraint Including systematic errors: Ronald Lipton, Moriond EW2005

19. Prospects • D0 DG 3 angle analysis • CDF DG updated analysis • ff, fk* • Explore CP violation (f) • Continue to improve lifetime precision • Improved understanding of systematics • Upgrades • D0 Layer 0 inside current silicon–improve s(ct), Silicon track trigger • DAQ – improve bandwidth • CDF Trigger and DAQ upgrades D0 Layer0 Ronald Lipton, Moriond EW2005

20. Backups Ronald Lipton, Moriond EW2005

21. Hadronic Lifetimes Systematic Uncertainties Ronald Lipton, Moriond EW2005

22. 3 Angles  1 Angle Inserting H( cos) =1, and F() =1 + J cos(2) + K cos2(2), and integrating over cos and , we obtain a 1-angle time evolution: = 0.355 ± 0.066 (from CDF) Ronald Lipton, Moriond EW2005

23. MC Acceptance F() = 1 + J cos(2) + K cos2(2) G(cos ) = 1 + Bcos(2) + Ccos(4) H(cos y ) flat distribution Ronald Lipton, Moriond EW2005

24. Bs Mixing Sensitivity Improvement due to Layer 0 current tracking Ronald Lipton, Moriond EW2005