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B Hadron Mixing and Lifetimes

B Hadron Mixing and Lifetimes. Mike Hildreth Universit é de Notre Dame du Lac. 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

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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 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 • Excellent Tracking Coverage |h|<3 • Impact Parameter Trigger @ L2 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 invariant mass trigger @ L1 • Impact Parameter Trigger @ L2 Central Tracker Forward Calorimeter (E) Silicon Lumi Monitor Mike Hildreth – B-mixing and Lifetimes TOF

  4. B-Factory Detectors Common Features: • Excellent Mass Resolution • Excellent EM Energy Resolution • Excellent Particle ID (TOF/aerogel/DIRC) 1. Silicon Vertex Detector 2. Central Drift Chamber 3. Aerogel Cerenkov Counter 4. Time of Flight Counter 5. CsI Calorimeter 6. KLM Detector 7. Superconducting Solenoid 8. Superconducting Final Focussing System U(4s) Running: • Coherent B-B production • Beam constrained mass  excellent background rejection Mike Hildreth – B-mixing and Lifetimes

  5. Datasets Tevatron: • >3 fb-1 delivered to each experiment • Peak lumi ~ 3x1032/cm2/s • up to 10 interactions/x-ing • Summer results include up to 2.4 fb-1 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

  6. Heavy Flavor Factories: • Tevatron Cross Sections: • central (|y|<1) b’s at 10kHz • central charm at 500kHz • ~9x1010 b’s already in Run II • ~6x1012 charm hadrons ~ infinite statistics for some studies  If you can trigger... (S/N ~ .006) • muon triggers, all-charged modes • B-Factory Cross Sections: • B’s at ~ 50 Hz • clean initial state • E(Y(4S))/2 – MB ~ 300MeV • ~no extra particles • “easy” B selection • coherent B-B production • “automatic” flavor tagging Belle CDF 360 pb-1 even works at Y(5S): MC Mike Hildreth – B-mixing and Lifetimes

  7. 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

  8. 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

  9. 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

  10. 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

  11. DØ (1.2-1.3 fb-1) all-charge decay mode LbJ/YL semi-leptonic mode LbLcmn similar topology control modes: B0J/Y Ks (all-charged) B0D*mnX (semi-leptonic) B+D0mnX (semi-leptonic) BsDsmnX (semi-leptonic) Lifetime from mmL or Lcm vertex CDF (1 fb-1) all-charge decay mode 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 Mike Hildreth – B-mixing and Lifetimes

  12. 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 N(J/YL) = 171 Mike Hildreth – B-mixing and Lifetimes

  13. 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 proper decay length • Nsignal, Nbkg, errors determined from mass fits • mass and width held constant Mike Hildreth – B-mixing and Lifetimes

  14. 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

  15. Lb Lifetime: Summary not in average not in average PDG 2007 PDG 2006 more statistics definitely coming... Mike Hildreth – B-mixing and Lifetimes

  16. B Hadron Mixing • For neutral B Hadrons, 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

  17. 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 • true Bell’s inequality test impossible due to short B lifetime, passive nature of flavor measurement Quantum Mechanics: Spontaneous Decoherence: Local Realistic Model: Mike Hildreth – B-mixing and Lifetimes

  18. Quantum Coherence • Fits of flavor asymmetry to different coherence models • spontaneous decoherence disfavored by 18s, local reality model disfavored by 5.1s Mike Hildreth – B-mixing and Lifetimes

  19. Bs Mixing Measurements at the Tevatron • Time-dependent flavor evolution of Bs measured directly • Three ingredients: • measurement of production flavor • hardest part of measurement • 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 Mike Hildreth – B-mixing and Lifetimes

  20. 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 Mike Hildreth – B-mixing and Lifetimes

  21. 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

  22. CDF Results semi-leptonic combined BsDsp Mike Hildreth – B-mixing and Lifetimes

  23. DØ Results • Numerous improvements to analysis • combined “event charge” flavor tag (D2 = 4.49%) • more refined momentum determination for semi-leptonic decays • event-by-event resolution rescaling • Addition of new tracking layer for Run IIb DØ Run II Preliminary DØ Run II Preliminary 3.1s statistical significance Mike Hildreth – B-mixing and Lifetimes

  24. constraints on new physics in B-mixing Mike Hildreth – B-mixing and Lifetimes

  25. DGs/Gs and fs • First Tevatron measurement with direct bearing on CP violation in the Bs system (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

  26. 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

  27. DGs/Gs Measurements New Measurement from CDF: • very loose pre-selection • Neural Net used to maximize S/S+B; ~2500 BsJ/ decays Mike Hildreth – B-mixing and Lifetimes

  28. DGs/Gs Measurements • CDF Angular projections: • Similar Results from DØ PRL 98 , 121801 (2007) (Lifetime-enhanced cuts) Mike Hildreth – B-mixing and Lifetimes

  29. 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 assymetry, Dms Mike Hildreth – B-mixing and Lifetimes

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