1 / 32

B mixing and lifetimes at the Tevatron

B mixing and lifetimes at the Tevatron. FPCP 2006 Vancouver. Jónatan Piedra LPNHE-University Pierre et Marie Curie / CNRS-IN2P3 on behalf of the D  and CDF Collaborations. Outline. THIS TALK. OTHER TALKS. CDF and D  detectors CDF and D  Hot Topics Detailed B s mixing at D 

Télécharger la présentation

B mixing and lifetimes at the Tevatron

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. B mixing and lifetimes at the Tevatron FPCP 2006 Vancouver Jónatan PiedraLPNHE-University Pierre et Marie Curie / CNRS-IN2P3 on behalf of the D and CDF Collaborations

  2. Outline THIS TALK OTHER TALKS • CDF and D detectors • CDF and D Hot Topics • Detailed Bs mixing at D • D. Buchholz • D Hot Topics • Detailed B  hh • D. Tonelli • CDF Hot Topics • Bc lifetime • I. Kravchenko • B Spectroscopy • Bs Ds Ds • R. Van Kooten • Bs Decays and B leptonic decays • Precision B Lifetimes • motivation • Lb • Bs • Bs lifetime difference • B Mixing • current status • ingredients • results • Summary J. Piedra

  3. Precision B Lifetimes

  4. Precision B Lifetimes Motivation C. Tarantino, hep-ph/0310241 THEORY (NLO) EXPERIMENT • b-hadron decays dominated by b-quark • Light quarks are included with 1/mb perturbative expansions (HQE) • expect small differences between lifetimes of different species • lifetime ratios reduce theory uncertainties J. Piedra

  5. Precision B LifetimesLb Lifetime CDF 370 pb-1 D250 pb-1 PRL 94 102001 (2005) • CDF and D have measured Lb J/L lifetime • Better proper time resolution than LbLc ln(world average dominated) • Earlier t(Lb)/t(B0) predictions were 2s above experiment • new calculations including higher order effects predict lower ratio

  6. Precision B LifetimesLb Lifetime at CDF CDF 370 pb-1 HFAG • Analysis based upon 370 pb-1 • Technique • unbinned maximum likelihood fit to proper decay-length and mass • Lb J/L0194  23 candidates • J/mm • L0 pp - • Use B0 reference mode • larger yield and similar decay topology • B0 Jpsi Ks01225  53 candidates • J/mm • Ks0p +p -

  7. Precision B LifetimesBs Lifetime CDF 360 pb-1 D400 pb-1 • D and CDF measure lifetime in best in the world

  8. Precision B Lifetimes Neutral Meson Mixing • Quark mixing  non-diagonal Hamiltonian for • Diagonalizing the Hamiltonian results in • two eigenstates and • two masses mH and mL, with Dm  mH – mL • two decay widths GH and GL, with DGGL– GH R. Van Kooten Bs decays and B leptonic decays

  9. Precision B LifetimesBs Lifetime Difference • Bs J/ • Pseudoscalar  Vector - Vector • Decay amplitude decomposed into 3 linear polarization states • A0 = S + D wave  P even • A|| = S + D wave  P even • A = P wave  P odd • If CP violation neglected • Bs,Light  CP even • Bs,Heavy  CP odd • angular distributions are different • Angular analysis separates CP eigenstates  measure two lifetimes J. Piedra

  10. Precision B LifetimesBs Lifetime Difference CDF 260 pb-1 D800 pb-1

  11. Precision B Lifetimes................... and best in the world CDF 360 pb-1 D210 pb-1 CDF 360 pb-1 • First measurement(~95% CP even) D. Tonelli CDF Hot Topics • Expected • Lifetime extracted from decay I. Kravchenko B Spectroscopy

  12. Precision B Lifetimes HFAG • B+andB0 at LEP/SLC, B factories and Tevatron (CDF/D) • dominated by Belle and BaBar • Bs dominated by Tevatron, LEP • Bc at Tevatron • Lb dominated by LEP, Tevatron

  13. B Mixing

  14. B Mixing Theoretical Prediction CKM fit • SM prediction for the ratio of Bs and B0 mixing frequencies • Dmd precisely measured • Dms not yet measured precisely • Potential NP discovery J. Piedra

  15. B Mixing Significance S signal candidates B background candidates sct time resolution • The dilution D measures the purity, D= 0 (1) random (perfect) tagger • The dilution attenuates the observed oscillations

  16. B Mixing Ingredients Opposite Side Trigger Side

  17. B Mixing Reconstructed...................... D1 fb-1 CDF 1 fb-1 • D exploits semileptonic decays from m trigger • CDF uses both electrons and muons

  18. B Mixing Reconstructed..................... • CDF collects hadronic B decays by triggering on impact parameter • Around 3700 Bs signal candidates J. Piedra

  19. B Mixing Proper Decay Time • Procedure • measure pT of Bdaughter tracks • measure the decay length Lxy • boost B back to its rest frame • Fully reconstructed decays • all daughters reconstructed • Partially reconstructed decays • some tracks escape detection  need simulation J. Piedra

  20. B Mixingb-Flavor Tagging • A flavor tagger determines the b-flavor at production time • bb production  flavor tagging on the Trigger Side or the Opposite Side • Soft Lepton Tagger • look for B  lnDX decay on the OS • lepton charge indicates b-flavor • Jet Charge Tagger • look for jet or secondary vertex from OS • jet charge indicates b-flavor • Same Side (Kaon) Tagger • look for a fragmentation track on the TS • it is charge correlated with the b-flavor SLT Trigger Side JQT Opposite Side SS(K)T J. Piedra

  21. B Mixing Flavor Analysis on B+ and B0 combined eD2 (%) D CDF 2.48  0.22 1.55  0.08 • Calibrate opposite side flavor taggers prior to Dms analysis • combine several B+,0 decays • combine all taggers • Direct Dmd measurement • cross-check for Bs mixing asymmetry D semileptonic 1 fb-1 Dmd= 0.506  0.020 (stat)  0.016 (syst) ps-1 CDF semileptonic 1 fb-1 Dmd= 0.509  0.010 (stat)  0.016 (syst) ps-1 CDF hadronic 355 pb-1 Dmd= 0.536  0.028 (stat)  0.006 (syst) ps-1 world average Dmd= 0.508  0.004 ps-1

  22. B Mixing SSKT at CDF • Look for the fragmentation track that is charge correlated with the B • Dms not yet measured precisely • Parameterization from MC • Extensive data/MC comparisons on all tagging related quantities • Rely on MC prediction of SSKT performance for Bs mixing

  23. B Mixing SSKT at CDF CDF MC 355 pb-1 • Systematic studies cover • quark fragmentation model • bbproduction mechanisms • excited B mesons content • detector / PID resolution • particle species content around B • data / MC agreement • Select track within DR < 0.7 around B most likely to be a kaon • based on dE/dx and TOF information

  24. B Mixing Fourier Analysis frequency domain time domain • Two domains to fit for oscillations • time fit for a cosine wave • frequency examine f-spectrum • Time domain approach • fit for Dms in P(t) ~ 1Dcos(Dmst) • Frequency domain approach • introduce amplitude, P(t) ~ 1ADcos(Dmst) • fit for A at different Dms  obtain frequency spectrum A(Dms) • standard method for combining limits • with flavor taggers calibrated A = 1 for the true Dms else A = 0

  25. B Mixing Amplitude Scans on Dmd D Run II Preliminary • The yellow band is 1.645sA around data points • Dm values where A + 1.645sA < 1 are excluded at 95% CL • Sensitivity is where 1.645sA = 1 1 fb-1 Amplitude scan works on B0 decay modes

  26. B Mixing Amplitude Scans on Dms D1 fb-1 CDF 355 pb-1 95% CL limit 14.8 ps-1 95% CL limit 8.6 ps-1 sensitivity 14.1 ps-1 sensitivity 13.0 ps-1 A/sA(Dms = 19 ps-1) = 2.5 5%p-value SSKT not yet included J. Piedra

  27. B Mixing Log Likelihood Scan hep-ex/0603029 submitted to Phys. Rev. Lett. • 17 < Dms < 21 ps-1 @ 90% CL assuming Gaussian uncertainties

  28. B Mixing D Effect on World Average HFAG preliminary (correlated systematics not included) D • A(Dms = 19 ps-1) • 1.5 sA2.3 sA D

  29. Summary • New Lb lifetimes reduce distance with theory • Tevatron measures the best Bs lifetimes in the world • Bs lifetime difference within SM • DBs oscillation • 1 fb-1 • 2.5 sA excess at Dms = 19 ps-1(5%p-value) • 17.1 < Dms < 21.1 ps-1 @ 90% CL • CDF Bs oscillation • 355 pb-1 • Dms > 8.6 ps -1 @ 95% CL

  30. Backup

  31. Precision B Lifetimes Transversity Basis  • Transversity basis J/ rest frame •  flight direction +x • KK plane xy plane J. Piedra

  32. B Mixing Semileptonic Decay Time • Missing particles  missing pT • Determine pseudo-ct from data • ct = ct* kMC • include kMC effect in signal PDF J. Piedra

More Related