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Measurements of the Masses, Mixing, and Lifetimes, of B Hadrons at the Tevatron

Measurements of the Masses, Mixing, and Lifetimes, of B Hadrons at the Tevatron. Mike Strauss The University of Oklahoma The Oklahoma Center for High Energy Physics for the CDF and D Ø Collaborations. Outline. B Physics at the Tevatron B Resonances B 0 oscillations B Lifetimes

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Measurements of the Masses, Mixing, and Lifetimes, of B Hadrons at the Tevatron

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  1. Measurements of the Masses, Mixing, and Lifetimes, of B Hadrons at the Tevatron Mike Strauss The University of Oklahoma The Oklahoma Center for High Energy Physics for the CDF and DØ Collaborations

  2. Outline • B Physics at the Tevatron • B Resonances • B0 oscillations • B Lifetimes • Exclusive Decays • Lifetime Ratios and Differences Mike Strauss The University of Oklahoma

  3. Tevatron Luminosity • ~0.5 fb–1 delivered this year • Detectors collect data at typically 85% efficiency • These analyses use 150–350 pb–1 • About 150 pb–1 of data has been recorded and is currently being analyzed Mike Strauss The University of Oklahoma

  4. Why B Physics? • Understanding the structure of flavour dynamics is crucial 3 families,handedness, mixing angles, masses, … any unified theory will have to account for it • Weak decays, especially mixing, CP violating and rare decays, provide insight into short-distance physics • Short distance phenomena are sensitive to beyond-SM effects • CKM matrix determines the charged weak decays of quarks, tree level diagrams, one-loop transitions… • Lifetime measurements probe QCD at large distances and give information on form factors and quark models Mike Strauss The University of Oklahoma

  5. B Physics at the Tevatron s(ppbb) 150 mb at 2 TeV s(e+e-bb) 7 nb at Z0 s(e+e-bb) 1 nb at (4S) • Large production cross sections • All B Hadrons produced (Best Bs and b) • Larger inelastic cross section (S/B  10-3) • Specialized Triggers: • Single lepton triggers • Dilepton triggers (e.g. J/+- ) • L1 Track triggers • L2 displaced track trigger for CDF Mike Strauss The University of Oklahoma

  6. Detectors Silicon vertex tracker, Axial solenoid, Central tracking, High rate trigger/DAQ, Calorimeter, Muon system CDF DØ Excellent muon ID; || < 2 Excellent calorimetry Tracking acceptance || < 2-3 L3 trigger on impact parameter L2 trigger on displaced vertexes Low p particle ID (TOF and dE/dx) Excellent mass resolution Mike Strauss The University of Oklahoma

  7. DØ Tracker SMT + CFT max = 1.65 SMT region max = 2.5 SMT  = - ln (tan(/2)) Mike Strauss The University of Oklahoma

  8. Silicon Microstrip Tracker (SMT) 4 H-disks 12 F-disks 6 Barrels Multi-layer barrel cross-section 3m2 of silicon Mike Strauss The University of Oklahoma

  9. Tracking Performance pT spectrum of soft pion candidate in D*D0 Muon h in J/y events Coverage of Muon system is matched by L3/offline tracking Tracks are reconstructed starting from pT = 180 MeV Mike Strauss The University of Oklahoma

  10. SMT Resolution and dE/dx Impact Parameter Resolution SMT dE/dx MC  Data Can provide: K/ separation for Ptot< 400 MeV p/ separation for Ptot<700 MeV NOT yet used for PID (DCA)  53 m @ PT = 1 GeV and 15 m @ higher PT Mike Strauss The University of Oklahoma

  11. Belle’s Discovery of X(3872) X J/ p+p- • No signal in gXc1 decay • Mass doesn’t fit easily into charm spectroscopy models • Near D0 D*0 threshold • Charmonium? A loosely bound meson state? MX = 3872.0  0.6 (stat)  0.5 (sys) Mike Strauss The University of Oklahoma

  12. X(3872) CDF and DØhave confirmed Belle’s discovery of the X(3872) • 730  90 candidates • ~12 s effect MX = 3871.3  0.7 (stat)  0.4 (sys) MeV/c2 DM = 774.9  3.1(stat)  3.0 (sys) MeV/c2 M +M(J/)= 3871.8 4.3 MeV/c2 Mike Strauss The University of Oklahoma

  13. Long Lifetime fraction of X(3872) Is the X charmonium, or something else? X(3872): y(2S): y(2S): 28.3±1.0(stat) ±0.7(syst)% X(3872): 16.1±4.9(stat) ±2.0(syst)% Mike Strauss The University of Oklahoma

  14. pT>15 GeV/c Iso=1 dl<0.1 |y|<1 cosqm<0.4 cosqp<0.4 X(3872) – y(2S) comparison Is the X charmonium, or something else? DØ multi-parameter comparison Mike Strauss The University of Oklahoma

  15. First Observation of BS   • Charmless BVV decay not yet observed • Dominated by penguin contributions • Cuts optimized on Bs J/  • BR error on this decay is • dominant systematic uncertainty BR(Bsff ) = 1.4 ± 0.6(stat) ± 0.2(syst) ± 0.5(BR)×10-5 Mike Strauss The University of Oklahoma

  16. B h±h+ Fractions • h, h = p, K • Motivation is to construct many charmless two body decays for CP studies • Hadronic B trigger using SVT • dE/dx and a used for PID • Signal reconstructed with vertex constrained fit • Fractions measured with unbinned likelihood fit using Mpp, a, ID1, ID2. Mike Strauss The University of Oklahoma

  17. PID using a = (1-p1/p2)q1 Mike Strauss The University of Oklahoma

  18. B h±h+ Fractions Mike Strauss The University of Oklahoma

  19. B h±h+ Fractions Assuming Bs K+K- is 100% CP even, DGs/Gs = 0.12±0.06, Gs=Gd, Mike Strauss The University of Oklahoma

  20. Search for B0(s,d)+– SM BR(Bs0+-)(3.40.5)×10-9; BR(Bd0+-)(1.50.9)×10-10 Expected BG: 1.05 ± 0.30 Expected BG: 3.7 ± 1.1 events BR(Bs0+–): < 7.5×10-7 at 95% CL (CDF) BR(Bs0+–): < 4.2×10-7 at 95% CL (DØ) BR(Bd0+–): < 1.9×10-7 at 95% CL Mike Strauss The University of Oklahoma

  21. Observation of B** • B Spectroscopy: • B (Jp= 0–) • B*(Jp= 1–) – decays to Bγ (100%) • ΔM = M(B*) – M(B) = 46 MeV/c2 • The B** consists of four separate states • 2 narrow states B1 (1+) and B2*(2+), decay via D-wave; • 2 wide states B0*(0+) and B1' (1+), decay via S-wave; • None of these individual states are well established • Decay channels used: • Bd**B±p +;B**+Bdp+;B**B*pBp (γ) • BJ/K±; Bd J/K*0; Bd  J/K0s – Mike Strauss The University of Oklahoma

  22. Distinct Narrow B** States 350 pb–1 • The first direct measurement of masses and splitting between B2* and B1 • M(B*) =M(B) + 46 MeV () Sum of 3 decay modes B1Bp () B2*Bp () B2*Bp M(B1) = 5724 ± 4 ± 7 MeV /c2 M(B2*) – M(B1) = 23.6 ± 7.7 ± 3.9 MeV/c2 Mike Strauss The University of Oklahoma

  23. Observation of BC J/y m X Combined unbinned likelihood fit made to mass and lifetime +0.14 M(Bc) = 5.95 ± 0.34 GeV/c2 -0.13 95±12±11 candidates +0.123 t(Bc) = 0.448 ± 0.121 ps -0.096 First 5s measurement Mike Strauss The University of Oklahoma

  24. Bs Ds–l+X Mike Strauss The University of Oklahoma

  25. Ds D*s and others Fully Reconstructed Bs Useful for Bs Mixing CDF “golden channels”: Bs Dsp Dsfp , K*K, ppp Bs Dsp p p Mike Strauss The University of Oklahoma

  26. Bd Mixing • In SM Bd mixing is explained by box diagrams • Constrains Vtd CKM matrix element • Mixing frequency mdhas been measured with high precision at e+e–B factories (0.502  0.007 ps-1) • md measurement at Hadron Colliders • Confirms initial state flavor tagging for later use in Bs and ms measurements Mike Strauss The University of Oklahoma

  27. b B0– b B–+ b – B Oscillation Variables Opposite side Same side b–1/3 Q<0 b  K– (CDF) BsK+ (CDF) Mike Strauss The University of Oklahoma

  28. Final State Ambiguities in SS Tag Mike Strauss The University of Oklahoma

  29. B0 Mixing with SS Tag NRS:N(B0p+) NWS:N(B0p–) A = (NRS– NWS )/(NRS+ NWS ) md= 0.443  0.052(stat)  0.030(sc)  0.012(syst) ps-1 Mike Strauss The University of Oklahoma

  30. B0 Mixing with SS Tag Bm D*X, D*D0p Visible Proper Decay Length: xM = Lxy MB c /pTmD Tagging purity: 55.8 ± 0.7 ± 0.8 % Preliminary md= 0.488  0.066(stat)  0.044(syst) ps-1 Mike Strauss The University of Oklahoma

  31. B0 Mixing with OS  Tag • Decay Mode: • Bm D*X, D*D0p • Tagging: • muon pT > 2.5 GeV/c • cosDf(m,B)< 0.5 • Tagging efficiency: 4.8 ± 0.2 % • Tagging purity: 73.0 ± 2.1 % • Fit procedure • Binnedc2 fit Preliminary md = 0.506  0.055(stat)  0.049(syst) ps-1 Mike Strauss The University of Oklahoma

  32. B0 Mixing with Combined Tag • Uses BlD(*) • Lepton plus SVT trigger • Combines: • Same Side Pion Tagging • Opposite Side Muon Tagging • Opposite Side Jet Charge Tagging • With and without vertex tagging • Ten subsamples • Tagged with SST • Tagged with OST (3 samples) • Tagged with SST and OST that agree (3 samples) • Tagged with SST and OST that don’t agree (3 sample) • Tagging priority is determined Mike Strauss The University of Oklahoma

  33. Efficiency and Dilution Preliminary md = 0.536  0.037(stat)  0.009 (sc) 0.015(syst) ps-1 Mike Strauss The University of Oklahoma

  34. B0D*±m+X B0 Mixing with Combined Tag BD0m+X Kpp mass - Kp mass Dominated by B+ events Mike Strauss The University of Oklahoma

  35. B0 Mixing with Combined Tag • Soft muon tag • If not tagged by muon: • Opposite side jet charge • Soft Pion Soft muon tag D0m “asymmetry” Jet charge and pion Preliminary md = 0.456  0.034(stat)  0.025(syst) ps-1 Mike Strauss The University of Oklahoma

  36. B Hadron Lifetimes • Naive quark spectator model: a 1  3 decay processcommon to all B hadrons. • (NLO) QCD  Heavy Quark Expansion predicts deviations in rough agreement with data • Experimental and theoretical uncertainties are comparable • Lifetime differences probe the HQE to 3rd order in LQCD / mb • Goal: measure the ratios accurately Mike Strauss The University of Oklahoma

  37. B Hadron Lifetime Ratios Mike Strauss The University of Oklahoma

  38. +0.217 t(b) = 1.221 ± 0.043 ps -0.179 +0.169 (b)/(Bd0) = 0.874 ± 0.028 -0.142 b Lifetime DØ Preliminary New Measurement from DØ bJ/0 DØ DØ CDF Preliminary from 2003: t(b) = 1.25 ± 0.26± 0.10 ps Mike Strauss The University of Oklahoma

  39. Bs Lifetime using BsJ/ DØ CDF 250 pb-1 Preliminary Improvements since 2003: • Selection minimizes statsyst • 12 parameter maximum likelihood fit • 240 pb-1 DØ analysis is similar to this CDF “improved” analysis Mike Strauss The University of Oklahoma

  40. +0.098 t(Bs) = 1.444 ±0.020 ps -0.090 Bs Lifetime using BsJ/ CDF DØ Preliminary 250 pb-1 +0.008 t(Bs) = 1.369±0.100 ps -0.010 Uses one exponential decay in the fit Mike Strauss The University of Oklahoma

  41. +0.075 t(Bs)/t(B0) = 0.980 ±0.003 -0.070 Bd Lifetimes Using Bd  J/Ks*0 CDF DØ Preliminary 250 pb-1 +0.052 t(B0) = 1.539±0.051±0.008 ps t(Bd0) = 1.473 ±0.023 ps -0.050 t(Bs)/t(B0) = 0.890±0.072 Mike Strauss The University of Oklahoma

  42. B+ Lifetime Using B J/K+ t(B+) = 1.662±0.033±0.008 ps Most systematic uncertainties cancel in the ratio t(B+)/t(B0) = 1.080±0.042 Mike Strauss The University of Oklahoma

  43. Lifetime Ratio t (B+)/t (B0) Novel Analysis Technique using B mDc(*)X • Directly measure ratio instead of individual lifetimes • Split D0Kpsample: • D*+ (with slow p+) mainly from B0 • D0 mainly from B+ 2% BS 12% B+ D*+ μD0 86% B0 K+ μ+ π- D0 D*- 2% BS 16% B0 D0 B0 ν PV π- 82% B+ Mike Strauss The University of Oklahoma

  44. +π± Dominated by B+ decays Dominated by B0 decays D0 and D*+ Candidates 109k inclusive Bm n D0 candidates 25k Bμν D* candidates Mike Strauss The University of Oklahoma

  45. Lifetime Ratio t (B+)/t (B0) • Measure N(mD*+)/N(mD0)in bins of VPDL • In both cases fit D0 signal to extract N • Use slow pion only to distinguishB0 from B+ (not in vertexing, K-factors etc., to avoid lifetime bias) (B+)/(B0) = 1.093 ± 0.021(stat) ± 0.022(syst) Mike Strauss The University of Oklahoma

  46. Lifetime Ratio t (B+)/t (B0) Mike Strauss The University of Oklahoma

  47. B Decay Angular Amplitudes • Uses Bs J/f ; Uses Bd J/K*0 • Allows measurement of many parameters including polarization amplitudes and DGs = 1/tL – 1/tH CP odd CP even Initial particle or antiparticle Mike Strauss The University of Oklahoma

  48. Decay Modes Mike Strauss The University of Oklahoma

  49. Transversity Angles • The J/yrest frame • KK defines (x,y) plane • K+(K) defines +y direction • Q, F: polar & azimuthal angles of m+ • Y: helicity angle of f(K*) Extract polarization amplitudes: A0: Longitudinal A, A: Transverse Mike Strauss The University of Oklahoma

  50. Angular Projections and fit for Bs Decay Angular Distribution: r =(Q, F, Y) Mike Strauss The University of Oklahoma

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