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B Hadron Mixing and Lifetimes

B Hadron Mixing and Lifetimes. Mike Hildreth Universit é de Notre Dame du Lac XXIII Lepton-Photon Symposium Daegu, Korea August 13-18, 2007. Overview. What are we after here? b, c Quark Production details of QCD, parton luminosities, fragmentation functions b, c Hadron Masses

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B Hadron Mixing and Lifetimes

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  1. B Hadron Mixing and Lifetimes Mike Hildreth Université de Notre Dame du Lac XXIII Lepton-Photon Symposium Daegu, Korea August 13-18, 2007 Mike Hildreth – B-mixing and Lifetimes

  2. Overview What are we after here? • b, c Quark Production • details of QCD, parton luminosities, fragmentation functions • b, c Hadron Masses • b, c Hadron Lifetimes • b, c Hadron Decays Tevatron and B-Factories Largely Complementary Tests of, inputs to HQE, CKM Extraction of CKM Parameters Heavy Quark Expansion Mike Hildreth – B-mixing and Lifetimes

  3. Tevatron Collider Detectors DØ: • Excellent Muon Coverage |h|<2 • L1 triggers.... • Excellent Tracking Coverage |h|<3 Central Calorimeter (E/H) Central Muon Solenoid Wall Calorimeter (H) Plug Calorimeter (E/H) Forward Muon CDF: • Excellent Mass Resolution • Particle ID: TOF and dE/dx • Two-track transverse mass trigger @ L1 • Impact Parameter Trigger @ L2 Central Tracker Forward Calorimeter (E) Silicon Lumi Monitor Mike Hildreth – B-mixing and Lifetimes TOF

  4. Datasets Tevatron: • ~3.3 fb-1 delivered to each experiment, ~2.8 fb-1 on tape • Peak lumi ~ 3x1032/cm2/s • up to 10 interactions/x-ing • Summer results include up to 2.4 fb-1 (May 30, 2007) Tevatron Integrated Luminosity B-Factories: • Belle: ~700 fb-1 • Babar: ~ 500 fb-1  1fb-1 = ~106 Bs • Peak luminosity: • 1.7x1034/cm2/s (KEKB) • 1.2x1034/cm2/s (PEPII) Integrated Luminosity [fb-1] Mike Hildreth – B-mixing and Lifetimes

  5. Heavy Quark Expansion: Lifetimes evaluation of LQCD/mQ terms requires knowledge of light quark dynamics in the presence of the heavy quark field • HQE: no leading order corrections  1/mQ • General feature of QCD gauge structure • hadronization and bound state effects given in terms of local HQ operators  Same operators used for CKM analyses! • Precise predictions possible: • verification tests calculational validity of HQE, supplies needed input for extraction of CKM parameters Bigi, Shifman, Uraltsev, Vainshtein mesons vs. baryons, (1%) B0 vs. B+ vs. Bs, (3-20%) e.g. Tarantino; Gabbiani, Onishchenko, Petrov e.g. Gabbiani, Onishchenko, Petrov Mike Hildreth – B-mixing and Lifetimes

  6. Lb Lifetime • One of the un-solved mysteries of HF lifetime measurements • long-standing discrepancy between theory and measurement • recent HQE calculation refinements • inclusion of sub-leading spectator terms • inclusion of NLO and 1/mb spectator effects • lowered expected value of • at time of HFAG 2006, theoretical predictions and experimental results agreed within ~1.2s • more accurate results needed for thorough test of theory  Updates of precision Lb lifetime measurements from CDF, DØ C. Tarantino hep-ph/0702235 Mike Hildreth – B-mixing and Lifetimes

  7. DØ (1.2-1.3 fb-1) fully-reconstructed LbJ/YL semi-leptonic mode LbLcmn similar topology control modes: B0J/Y Ks (all-charged) BsJ/Yf (all-charged) B0, B+DmnX (semi-leptonic) BsDsmnX (semi-leptonic) Lifetime from mmL or Lcm vertex CDF (1 fb-1) (Preliminary) fully reconstructed LbJ/YL similar topology control modes: B0J/Y Ks B0J/Y K* B+J/Y K+ BsJ/Yf Lifetime from mm vertex Lb Lifetime Measurements hep-ex/0704.3909 hep-ex/0706.2358 PRL, 94, 042001 (2005) PRL 94, 182001 (2005) PRL 97, 241801 (2006) Mike Hildreth – B-mixing and Lifetimes

  8. CDF: reoptimization and detailed study of resolution functions for J/Y and vertexing Results: DØ: extensive studies of non-prompt backgrounds Results: LbJ/YL Lifetime Measurements Mike Hildreth – B-mixing and Lifetimes

  9. LbLcmn Lifetime Measurement (DØ) • main issue: huge background after selection of the Lcm final state Likelihood for signal selection developed from data: B0 DmnX, DKsp Bs DsmnX, DsKsK cut • Global fit uses lifetime pdf to extract Lb lifetime from number of signal events/bin full sample: 4437±329 events B0/B+/BsD+mn, D+Ksp • c2 fit in bins of decay length • Nsignal, Nbkg, errors determined from mass fits • mass and width held constant Mike Hildreth – B-mixing and Lifetimes

  10. Lb Lifetime: Summary • Lifetime Cross Checks: DØ Run II (02-06) 1.501±0.078±0.050 ps not in average PDG 2006 Mike Hildreth – B-mixing and Lifetimes

  11. Lb Lifetime: Summary not in average not in average PDG 2007 PDG 2006 Tevatron: more statistics definitely coming... LHCb will certainly contribute Mike Hildreth – B-mixing and Lifetimes

  12. B Meson Mixing • For neutral B Mesons, Weak  Mass  CP eigenstates • time-dependent evolution • three observables characterize system: • Dm = MH-ML ~ 2|M12| • DGCP = Geven- Godd ~2|G12| • f = arg(G12/M12) f relates mass and CP eigenstates through DGs = GL-GH = DGCPcosfs • Mixing Measurements in Bd and Bs systems  access to CKM elements sensitive to New Physics not sensitive sensitive to New Physics • Dmd well-measured: 0.509±0.004 ps-1 • many uncertainties cancel in ratio Mike Hildreth – B-mixing and Lifetimes

  13. Quantum Entanglement • Belle: EPR tests of quantum coherence of Y(4S) • measurement of flavor asymmetry vs Dt can distinguish between models suggesting different degrees of coherence • essentially, test levels of coherence with Dt • true Bell’s inequality test impossible due to short B lifetime, passive nature of flavor measurement Quantum Mechanics: Spontaneous Decoherence: Rev. Mod. Phys. 64, 339 (1992) Local Realistic Model: Eur. Phys. J. C. 14, 469 (2000) Models of decoherence include dependence on the absolute times of the decays, instead of a pure Dt form Mike Hildreth – B-mixing and Lifetimes

  14. Quantum Coherence QM SD PS • flavor asymmetry studied in bins of Dt (~150fb-1) • high-purity flavor tags used to optimize sensitivity to deviations • backgrounds and mistags subtracted bin-by-bin, deconvolution used to extract true asymmetry distribution • weighted least-squares fit to the different models for A, including a term containing world-average Dmd • Belle/BaBar values assuming QC excluded • QM favored over SD by 13s, over PS by 5.1s • additional fit for fraction l of instantaneous decoherence yields , consistent with no decoherence Mike Hildreth – B-mixing and Lifetimes

  15. Leptonic Decay Asymmetries in Bs • If there is no direct CP violation in the Bs system, semi-leptonic decays are a direct tag of the flavor state: • CP-violation in mixing can then be explored using decay asymmetries: • In fact, a flavor tag of the initial state is unnecessary, use untagged: • Since the state is untagged, measurement of oscillation is also unnecessary; use time-integral of distribution: • ASL is the time-integrated untagged asymmetry SM: aSL = (0.21± 0.04)∙10-4 sensitivity to New Physics Mike Hildreth – B-mixing and Lifetimes

  16. ASL in Bs Decays • DØ Analysis: Use BsDsmnX, Dsfp, fKK (1.3 fb-1) • Experimentally, • Break data set into 8 equal portions based on muon direction(g), muon toroid polarity(b), solenoid polarity, and muon charge(q) • Fit separately for Ds, D, and background components from sidebands to extract physics and detector-induced asymmetries • background fits consistent with 0 • correcting for flavor composition: yields PRL 98, 151801 (2007) (constraints on fs will be discussed later) Mike Hildreth – B-mixing and Lifetimes

  17. Bs Mixing Measurements at the Tevatron DØ MC Bs→mfp sVPDL DØ: new inner Si layer <s>=48mm Bs Lifetime DØ: old <s>=67mm CDF: Ds <s>=45mm Dms = 17 ps-1 CDF: Dsp <s>=26mm cm • Time-dependent flavor evolution of Bs measured directly • Three ingredients: • measurement of production flavor • various indirect techniques based on properties of associated fragmentation and decay products • measurement of decay flavor • flavor-specific final state or lepton decay flavor • proper time of decay • position resolution of tracking system • momentum resolution critical for background suppression t (lifetimes) Mike Hildreth – B-mixing and Lifetimes

  18. Semi-leptonic: most numerous, but missing neutrino spoils proper time resolution Specific Hadronic Final States: all-charged final states give excellent vertex resolution Bs Mixing Measurements: final states 2.4 fb-1 CDF Run II Data Samples: part. rec. 3100 New Analysis *all muon-tagged Mike Hildreth – B-mixing and Lifetimes

  19. Bs Mixing Measurements: flavor tag • No luxury of coherent B0-B0 initial state for flavor tagging • need to use as much information as possible in the event to determine production flavor • Figure of Merit: D2  efficiency of tag x (dilution factor)2 final state tags decay flavor • Kaon flavor: bcXK- • lepton flavor: bX-, but bcX+ • jet charge: momentum-weighted charge of initial fragmentation tracks • Kaon flavor: strange quark not included in Bs forms Kaon CDF achieved: D2 = 1.8% (OST) D2 = 3.7% (SSThad), 4.8%(SSTlep) Mike Hildreth – B-mixing and Lifetimes

  20. CDF Results PRL 97, 242003 2006 semi-leptonic combined BsDsp Mike Hildreth – B-mixing and Lifetimes

  21. DØ Results • Numerous improvements to analysis • combined OS+SS Tagging (D2 = 4.49%) • more refined momentum determination for semi-leptonic decays • track-by-track resolution rescaling • Addition of new innermost tracking layer for Run IIb DØ Run II Preliminary DØ Run II Preliminary 3.1s statistical significance Mike Hildreth – B-mixing and Lifetimes

  22. DGs/Gs and fs • First study of CP violation in the Bs mixing (sensitive to New Physics!?) • define Heavy (H, CP-odd) and Light (L, CP-even) Bs states: • GH and GL are partial widths, DGs = GL-GH, Gs=1/2(GH+GL) • Differential decay rate (Lifetime difference!): • fs 0  new CP-violation; expected SM value is very small CP-even angular configurations (L=0, 2) CP-odd angular configuration (L=1) ; Mike Hildreth – B-mixing and Lifetimes

  23. DGs/Gs Measurements Strategy: • Choose decay with definite CP states: BsJ/, J/m+m-, K+K- • Vector mesons in final state are CP-odd (L=1) or CP-even (L=0,2) • rate depends on relative orientation of meson polarization • time-dependent angular distributions allow separation of BsLand BsH components • Simultaneous fit to lifetimes, angle space • modifications of angular distributions due to acceptance effects taken from MC models Mike Hildreth – B-mixing and Lifetimes

  24. DGs/Gs Measurements New Measurement from CDF: • very loose pre-selection • Neural Net used to maximize S/S+B; ~2500 BsJ/ decays (fs = 0) cf. DØ: 1.52 ± 0.04 ± 0.02 PRL 98 , 121801 (2007) Mike Hildreth – B-mixing and Lifetimes

  25. DGs/Gs Measurements • CDF Angular projections: • Similar Results from DØ PRL 98 , 121801 (2007) (Note: DØ plots have signal content enhanced with lifetime cuts) Mike Hildreth – B-mixing and Lifetimes

  26. Constraints on fs • CDF • allowed region in DG/fs plane determined by frequentist method to account for biases at low values of DG or fs hep-ex/0702030 contours • DØ: • combined constraints from BsJ/, semileptonic charge asymmetry, lifetime, CDF Dms Mike Hildreth – B-mixing and Lifetimes

  27. Conclusions & Outlook • Incredibly rich menu of B physics on offer • mature experiments at Tevatron and B-Factories • sophisticated techniques emerging to extract the most information available from the data • HUGE datasets, with more to come • largely complementary in focus, scope • Exploration of flavor sector with unprecedented detail • see following talks... Mike Hildreth – B-mixing and Lifetimes

  28. Backup Slides Mike Hildreth – B-mixing and Lifetimes

  29. Quarkonia: Upsilon Polarization Cho, Wise, PLB 346, 129 (1995) • Non-relativistic QCD (NRQCD) predicts significant polarization at high pT • Production described by short distance cross sections  non-perturbative matrix elements for evolution to quarkonium state. • color octet modes required on top of color singlet to describe production (demonstrated by CDF in Run I) • New results from DØ: (1S) and (2S) production,  final state • measurements of polarization in rest frame of Y: Bodwin, Braaten, Lepage, PRD51, 1125 (1995) Braaten, Fleming, PRL74, 3327 (1995) fit cosq* distribution in bins of pT to extract a where NRQCD prediction CDF Data (PRL 88 161802 (2002)) DØ Data NRQCD prediction kT factorization models Mike Hildreth – B-mixing and Lifetimes

  30. Belle: Y(5S) Studies Belle Preliminary 23.6 fb-1 Belle Preliminary 23.6 fb-1 • Belle took 23.6 fb-1 at the Y(5S) in 2006 • fs = (18 ± 1.3 ± 3.2) % (earlier results from 1.86fb-1) • [PRL 98 (2007) 052001, PRD 76 (2007) 012002] • New results on inclusive Bs semi-leptonic decays • inclusive spectra not accessible at the Tevatron Combined Result: c.f. the B0 system: d (PDG 2007) (see results on rare Bs decays later...) Mike Hildreth – B-mixing and Lifetimes

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