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B s and Λ b Lifetimes and BRs at the Tevatron

B s and Λ b Lifetimes and BRs at the Tevatron. Satyajit Behari (For the CDF Collab.) Johns Hopkins Univ., Baltimore,USA. 25 th September 2006 Beauty 2006, University of Oxford, UK. Contents. Introduction Lifetime Measurements Motivation

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B s and Λ b Lifetimes and BRs at the Tevatron

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  1. Bs and Λb Lifetimes and BRs at the Tevatron Satyajit Behari(For the CDF Collab.) Johns Hopkins Univ., Baltimore,USA 25th September 2006 Beauty 2006, University of Oxford, UK

  2. Contents • Introduction • Lifetime Measurements • Motivation • Λb lifetimes (Λb  J/ΨΛ) • Bs lifetimes • Flavor specific • t(Bs Ds ℓ n) • t(Bs Dsp, Dsppp) • ΔΓCP/ΓCP in tL(Bs  K+ K-) • ΔΓCP/Γ in BR(Bs  Ds(*) Ds(*)) • Summary • BR Measurements • BR(Bs  Ds(*) Ds(*)) • BR(Bs Ds1(2536) mn X) • BR(Bs Ds Ds) / BR(Ds D+) Other talks: • BR(Bs  mm) limits • [ Talk by Cheng-Ju Lin ] • ΔΓ in Bs  J/Ψ • [ Talk by Avdhesh Chandra ] S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

  3. Chicago  p p 1.96 TeV Booster p CDF DØ Tevatron p p source Main Injector & Recycler The Tevatron S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

  4. CDF and DØ Detectors in Run 2 • Both detectors • Silicon microvertex tracker • Solenoid • High rate trigger/DAQ • Calorimeters and muons L2 trigger on displaced vertices Excellent tracking resolution Good low momentum PID Good electron, muon ID and acceptance Excellent tracking acceptance || < 2-3 S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

  5. b g b g g q q q b b b b B Production at Tevatron q b b g g g Flavor Creation (gluon fusion) Flavor Creation (annihilation) Flavor Excitation Gluon Splitting • Tevatron is a source of all B-hadron • species, Bd, Bu, Bc, Bs and Λb • sb = 29.4 ± 0.6 ± 6.2 mb (|η| < 1) (CDF) • Huge cross-sections compared to the • the B-factories but proportionally large • backgrounds as well • Since (bb) << (pp) Events have to be selected with specific triggers • Trigger requirements:large bandwidth, background suppression, deadtimeless S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

  6. Primary vertex ~ 1 mm b decays Secondary vertex Impact parameter Triggers for B Physics • Single-/Di-lepton (CDF/DØ) A high pT lepton or two leptons with lower pT • J/Ψ modes, masses, lifetimes, x-section • Yields higher than Run I (low Pt threshold, increased acceptance) • lepton + displaced track - semileptonic sample (CDF) • pT(e/) > 4 GeV/c, 120 m < d0(Trk) < 1mm, pT(Trk) > 2 GeV/c • Semileptonic decays, lifetimes, flavor tagging • B Yields 3x Run I • Two displaced vertex tracks - hadronic sample (CDF) • pT(Trk) >2 GeV/c, 120 m < d0(Trk) < 1mm, SpT > 5.5 GeV/c • X-section, branching ratios, Bs mixing… S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

  7. Interests in B Hadron Lifetimes C. Tarantino, hep-ph/0310241 • Test of non-spectator effects in decays of heavy hadrons which give rise to lifetime hierarchy: t(B+) ≥t(B0) ≈t(Bs0) >t(Λb) »t(Bc) • Heavy Quark Expansion includes these effects (expansion in 1/mb) and predicts lifetime ratios: • t(B+)/t(B0) = 1.00 ± 0.05 x (fB/200 MeV)2 • t(Bs0)/t(B0) = 1.00 ± 0.01 • t(Λb)/t(B0) ~ 0.9 • The B+,B0 lifetimes are precisely measured at B-factories. Λb and Bs0 ratios are unique to Tevatron. THEORY (NLO) EXPERIMENT S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

  8. Bs Lifetime Difference Bs has a large branching fraction to CP eigenstates Dominated by b  ccs transition: Bs  Ds(*)+Ds(*)- (Bd: b  ccd Cabibbo suppressed, 20x smaller) SM prediction:DGs/Gs= GL-GH = (9.3 ± 4.6) % (Beneke et al) hep-ph/0012222 -0.07 ( < 0.29 at 95% CL) World average:DGs/Gs = 0.07+0.09 (SLD, LEP, CDF I results + t(Bs)=t(Bd) constraint) • Ways to measure: • Compare t(Bs  CP even) to t(Bs  CP mixed or CP odd) • Angular analysis of Bs  J/yfseparates CP even and CP odd. • [ See the talk by Avdhesh Chandra ] • Indirect: Measure Br (Bs Ds(*)+Ds(*)-) , tL(Bs  K+ K-) S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

  9. Λb Lifetimes S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

  10. Λb Lifetime in Λb  J/ΨΛ • 1 fb-1 data • 174 ± 21 Λb events • Extract lifetime by an unbinned maximum likelihood fit to mass and proper decay length. • Major source of systematic is contamination from B0 • Using B0 J/Ψ Ks0 lifetime: S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

  11. Λb Lifetime in Λb  J/ΨΛ • 1 fb-1 data • 538 ± 38 Λb events • Major sources of systematics are due to modeling of ct resolution and V0 pointing • Using world average B0 J/Ψ Ks0 lifetime: World best measurement! S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

  12. Λb Lifetime – Measurement vs Theory t(Λb)/t(B0) • The world average on t(Λb)/t(B0) measurements used to show ~2σ lower value than the NLO prediction so far. • The new result sits above the prediction! • Need more experimental inputs to conclude the issue. • Looking forward to t(Λb) in fully hadronic decay modes, e.g. Λb  Λcp. S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

  13. Bs Lifetime Differences S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

  14. 360 pb-1 400 pb-1 Bs Lifetime t(Bs Ds ℓ n X) World’s best result! S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

  15. Bs Lifetime t(Bs Dsp, 3p) • Fully reconstructed hadronic decays from displaced track trigger • 360 pb-1 in CDF Run 2. • Trigger bias is removed by a Monte Carlo approach. • Mass and decay length fitted simultaneously to extract lifetime. • Would be updated for 1 fb-1 S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

  16. ΔΓCP/ΓCP in tL(Bs  K+ K-) • Measure tL (95% CP even state) • 360 pb-1 data from displaced track trigger • Four h+h- components are resolved by mass, kinematics and PID info. • Bd lifetime is fixed to world average • Dominant systematics from dE/dx based PID, MC pT input spectrum • Extract ΔΓCP/ΓCP using flavor specific t(Bs0) from other measurements. S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

  17. ΔΓCP/ΓCP in BR(Bs  Ds(*) Ds(*)) • 1 fb-1 sample • Ds fp, Ds  fmn, (f  K+ K-) • Start with mDs sample (Ds  fp), look for additional f (mDsf sample) • Ratio of efficiencies estimated using simulated events. • Directly fit Ds mass distribution to extract N(mDs). Unbinned likelihood to extract N(mfDs) (Lower statistics) • N (mDs) = 15225 310 • N(mfDs) = 19.3 7.9 • Dominant sources of systematics: • BR(Bs mnDs(*)) • MC pT reweighting S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

  18. Tevatron ΔΓCP/ΓCP Summary S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

  19. Bs Branching Fractions S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

  20. Bs  Ds1(2536) m+ n X • c+s quark in L=1 state : Provide test HQET • A significant fraction of semileptonic decays : • Compare exclusive/inclusive decay rates • Extract CKM matrix elements • An additional channel for Bs mixing. • Need to develop more understanding in the light of discoveries which don’t agree with predictions : DsJ(2317), DsJ(2460), DsJ(2632) – SELEX and so on… • Bs  Ds**m n D* KS p p D0p K p S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

  21. Bs  Ds1(2536) m+ n X(Contd..) Comparison with theory BR(Bs->Ds1mnX) = 0.860.16 0.13 0.09 (%) ISGW2 0.53%, IQM 0.39%, HQET&QCD Sum rules 0.20% N = 42.6  8.6 ~ 5 s S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

  22. BR(Bs Ds Ds) / BR(B0 Ds D-) 5.8σ Observation! fs/fd * BR(Bs → DsDs ) / BR(B0 → DsD+) = 0.43 ± 0.11(Stat) ± 0.03(Syst) ± 0.10(BR) BR(Bs → DsDs ) / BR(B0 → DsD+ ) = 1.67 ± 0.41(Stat) ± 0.12(Syst) ± 0.24 (fs/fd) ± 0.39(BR) S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

  23. Summary • With over 1 fb-1 accumulated data / experiment and much more to come, heavy flavor physics at Tevatron is entering a precision era. • Using large Bs and Λb samples, unique to Tevatron, various theoretical predictions are put to stringent tests. Many world best measurements have been made. • Lifetimes in fully hadronic Λb decays are underway. Other excited baryonic modes to follow. • Check out more Tevatron B physics results: • CDF: http://www-cdf.fnal.gov/physics/new/bottom/bottom.html • DØ:http://www-d0.fnal.gov/Run2Physics/WWW/results/b.htm S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

  24. Backup-1 ΔΓCP/ΓCP in BR(Bs  Ds(*) Ds(*)) Background processes: S.Behari, Bs / Lb Lifetime and BRs at the Tevatron, Beauty 2006

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