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

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

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

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

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

Lifetime and 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. Semi-leptonic decays Fully reconstr. decays s(ct)/ct 2% 0.5% Donatella Lucchesi

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 to xs  30 Donatella Lucchesi

Bs mixing in fully hadronic decays 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

Optimize tracking and flavor tagging 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

Bs mixing at D0: Flavor tagging DØ Run-II Preliminary Muon Jet Charge (%) 8.2±2.2 55.1±4.1 D(%) 63.9±30.1 21.1±10.6 D2 (%) 3.3±1.8 (3.1 pred.) 2.4±1.7 (4.7 pred.) Donatella Lucchesi

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

Current status of CDF: Yield Study N(Bs) N(Bd) fs fd es ed 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

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

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

Backup slides Donatella Lucchesi

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 —sum BdK BsKK Bd  BsK  RunIIa: ACP(dir, mix)~0.2 (Bd) ~0.1 (BsKK) () = ±10(stat) ±3(theory) Donatella Lucchesi

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

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

Xs = Dms Bs measurement: CDF expectations 80K 40K 20K 10K 70K 60K 50K 30K Number of events for 5 sigma observation 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

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 Ds Ds*K Ds* DsK S/B = 1/6 S/B = 1 ~ 1000 events in RunIIa ~ 3500 events in RunIIb Donatella Lucchesi

 via B0 / BsKK R. Fleischer: B0 measure sin2(+) ( ~30% penguins contamination) P/T ratio measurement with a simultaneous fit of BsKK asymmetry Dominant Sub-dominant u - b W d u,c,t s 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