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B s Physics and Prospects at the Tevatron

This talk discusses the status of Bs physics at the Tevatron and covers topics such as lifetimes, mixing, and trigger strategies for collecting Bs decays. Several measurements and prospects for future studies are presented.

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B s Physics and Prospects at the Tevatron

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  1. Bs Physics and Prospects at the Tevatron Donatella Lucchesi for the CDF and D0 Collaborations CKM Workshop Durham April 5-9 2003 • The status of Bs physics at the Tevatron • Lifetimes • Mixing Other related talks : • J. Rademacker talk for lifetimes and lifetime differences • R. Oldeman presentation about detector performances • I. Villa talk about SVT trigger Donatella Lucchesi

  2. How do we collect Bs Old style: • Di-muon trigger: low Pt respect to Run I  much more J/ • BsJ/ “BsJ/” New era: • Hadronic trigger (SVT): displaced tracks all hadronic decays A combination of Old and New • Lepton + displaced track trigger BslDsX Donatella Lucchesi

  3. m(Bs)=5360.3±3.8(stat) (sys) MeV/c2 ichep result +2.1 -2.9 Exploiting the J/: Mass Measurement ichep Donatella Lucchesi

  4. BsJ/: Lifetime Measurement tB0=1.42±0.09(stat)±0.02(sys) tBs=1.26±0.20(stat)±0.02(sys) tBs/tB0= 0.89±0.15(tot.) Donatella Lucchesi

  5. Lifetime measurement: semi-leptonic decays Muons Electrons Signal to noise ratio better than expected ! Observed yield: RunI5 Donatella Lucchesi

  6. Lifetimeand DG Perspectives • CDF lifetime expectation in 2 fb-1 are: • BsJ/ and BslDsX combined  s(DG/G)few % for both CDF and D0 (see Jonas talk for details) • CP asymmetry in BsJ/expected small in S. M. • If bigger  new physics • If Dms larger: • difficult to measure also with high statistics sample • DG/G sizeable  easy to measure • Dms = DG·C where C can be calculated inside the S. M. Donatella Lucchesi

  7. Xs=DmsBs measurement: semi-leptonic decays Decays included: Bs  Dsl, Ds*l (Ds, K*0K, +) ~40K events in 2 fb-1 Proper time resolution: t = 60 fs  t  K/K K/K ~ 14% Tagging: D2 = 11.3 % (all taggers) CDF Current limit Xs> 20.6 Sensitive up toxs 30 Donatella Lucchesi

  8. Bs mixing in fully hadronic decays D0 Fully reconstructed decays Decays included: Bs Ds, Ds (Ds, K*0K, K*K0) BsJ/K*0 Proper time resolution: 0.40 ps Tagging: D2 = 3.1 % Jet Charge D2 = 4.7 % Lepton S/B: 1:2 Donatella Lucchesi

  9. Current status of D0 Total Luminosity: ~40 pb-1 Many B reconstructed see Jonas talk. Optimize tracking and flavor tagging B+J/K+ Pt>2 GeV all tracks 2.8 < mμμ < 3.3 GeV B decay length >0.3 mm Donatella Lucchesi

  10. Bs mixing at D0: Flavor tagging DØ Run-II Preliminary Donatella Lucchesi

  11. Current status of CDF: Yield Study Hadronic trigger First observation ! • Can we measure the yield? • fs/fd: discrepancy LEP - CDF • Branching Fraction: unknown • Cross section: big uncertainty Donatella Lucchesi

  12. N(Bs) fs es ed N(Bd) fd Current status of CDF: Yield Study Br(BsDs-p+) Br(Ds--) Br(k+k-) = Br(BdD-+) Br(D-k+--) PDG Monte Carlo Big effort in a full detector and trigger simulation optimization “a la LEP” to measure the efficiencies Donatella Lucchesi

  13. fs fd Br(BsDs-p+) Br(BdD-+) Current status of CDF: Yield Study BdD-+ , D-k+--) reconstructed New ! = 0.42 ± 0.11(stat.) ± 0.11(Br.) ± 0.07(syst.) Donatella Lucchesi

  14. Conclusions • CDF starts doing measurements with: • Bs semileptonic decays • BsJ/ and fully reconstructed hadronic decays • D0 has less integrated luminosity  tools optimization • Several improvements underway: • removing trigger rate limit • SVT increase efficiency • flavor tagging optimization Bd mixing measurements for • the summer • add all the other Ds decay channels ( see Rolf presentation for details) Donatella Lucchesi

  15. Backup slides Donatella Lucchesi

  16. —sum BdK BsKK Bd BsK  CP violation in Standard Model: g at CDF 1) R. Fleischer proposal: Fit the asymmetries in the B0/BsKK ACP=ACP(dir)cos(mt) + ACP(mix)sin(mt) • How do we separate /K/KK/K: • Inv. mass ~ 20 MeV/c2 • Kinematical variables • dE/dX • Md << Ms RunIIa: ACP(dir, mix)~0.2 (Bd) ~0.1 (BsKK) () = ±10(stat) ±3(theory) Donatella Lucchesi

  17. Bs mixing in fully hadronic decays Trigger on displaced tracks Many Ds reconstructed CDF + Ds + DsKs + Ds  K*0K …and the Bs? Donatella Lucchesi

  18. Bs mixing at CDF: Flavor tagging • Lepton (muon and electron) tagging: under optimization in a huge sample of B from the lepton+displaced track trigger • Same Side Tagging Donatella Lucchesi

  19. 80K 70K 60K 50K Number of events for 5 sigma observation 40K 30K 20K 10K 0 Xs =Dms Bs measurement: CDF expectations Fully reconstructed decays Decays included B0s Ds, Ds (Ds, K*0K, +) Proper time resolution: t = 45 fs  t  Pt/Pt (L00+SVX) Tagging: D2 = 11.3 % (all taggers) S/B: 2:1, 1:1, 1:2 Donatella Lucchesi

  20. Ds S/B = 1/6 Ds* DsK Ds*K S/B = 1 CP violation in Standard Model: g at CDF • 2) R. Aleksan et al. Z Phys. C54 653 (1992) proposal: • BsDsK time dependent decay rate depends on: • sin(dg) and cos(dg) • Theoretically clean • Reasonable Branching ratio • Background BsDsp • Need tagging • Need time dependent analysis ~ 1000 events in RunIIa ~ 3500 events in RunIIb Donatella Lucchesi

  21. R. Fleischer: B0 measure sin2(+) ( ~30% penguins contamination) P/T ratio measurement with a simultaneous fit of BsKK asymmetry - u W d u,c,t b b d u W - u W s u,c,t b s b u W  via B0 / BsKK Dominant Sub-dominant B0 BsKK Measurement of 4 asymmetries time dependent Fit of d=P/T ~ 0.3, =strong phase of P/T, ,  constrained from sin(2) Donatella Lucchesi

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