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B Lifetime and Oscillation Results from CDF and D0

B Lifetime and Oscillation Results from CDF and D0. Andrzej Zieminski Indiana University (for the D0 and CDF Collaborations) HCP 2004 East Lansing, June 16, 2004. Outline. Tevatron Run II – B triggers and data - on tape: > 370 pb -1 per experiment

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B Lifetime and Oscillation Results from CDF and D0

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  1. B Lifetime and Oscillation Results from CDF and D0 Andrzej Zieminski Indiana University (for the D0 and CDF Collaborations) HCP 2004 East Lansing, June 16, 2004

  2. Outline • Tevatron Run II – B triggers and data - on tape: > 370 pb-1 per experiment - results presented here: 180 – 270 pb-1 • B Meson Lifetimes from Exclusive Decays (CDF) -B+ J/ψ + K+ - B0d J/ψ + K* - B0s  J/ψ + φ • Polarization Amplitudes forB  J/ψ +V channels (CDF) t(B+)/t(B0d) Ratio from Semileptonic Decays(D0) • B0d oscillations using: - semileptonic decays, Opposite Sidem tag (D0) - hadronic exclusive decays, Same Sidep tag (CDF)

  3. pros Large bb cross section: ~ 150 µbarn total ~ 3-5 µbarn “reconstructible” At 4 x 1031cm-2s-1 ~ 150 Hz of “reconstructible” B’s All B species produced world best source of Bs and Λb Production incoherent reconstruction of both Bs not needed cons Large background - bb cross section ~10-3 total inelastic - special triggers (leptons, displaced tracks) - combinatorics in reconstruction Typical kinematic cuts: - pT(µ) > 1.5 GeV/c for µ’s from J/ψ - pT(B) > 5 (6) GeV/c B Physics at the Tevatron -

  4. Detectors CDF L2 trigger on displaced vertexes Particle ID (TOF and dE/dx) Excellent mass resolution DØ Excellent muon ID; || < 2 Excellent tracking acceptance || < 2-3 L3 trigger on impact parameter / L2 IP trigger being commissioned Both detectors Silicon microvertex tracker Axial solenoid Central tracking High rate trigger/DAQ Calorimeters and muons

  5. Di-muon pT(µ) > 3 GeV/c, |η (µ)| < 2.2 unprescaled , ~4Hz @ 40 E30 cm-2s-1 pT(µ)> 1.5 GeV/c, |η (µ)| < 2.2 Lumuminosity dependent prescale Single µ, pT (µ)> 3 - 5 GeV/c, |η (µ)| < 2.2 Luminosity dependent prescale unprescaled  ~50Hz @ 40 E30 cm-2s-1 Displaced tracks (L2) being commissioned Single-m & Di-muon (J/ψ) pT(µ) > 1.5 GeV/c , |η (µ) | < 0.6 pT(µ) > 2.0 GeV/c , 0.6< |η (µ) | < 1.0 Hadronic track triggers: Level 1 : Fast track trigger finds tracks with pT > 1.5 GeV/c Level 2 : Links tracks into silicon Finds tracks with impact parameter > 120 mm ↓ lepton+ displaced track pT(e/µ) > 4 GeV/c pT(trk) > 2 GeV/c 120 µm < d 0 (trk) < 1 mm two displaced tracks pT(trk) > 2 GeV/c , SpT > 5.5 GeV 120 µm < d 0 (trk) < 1 mm Triggers for B Lifetime/Mixing Studies

  6. Exclusive B decays (CDF) Mass measurements from exclusive BJ/y X channels: m(Bs ) & m(Lb) – the world best measurement

  7. 250 pb-1 Exclusive B Decays (D0) • D0 finds in ~250 pb-1: B+ J/y K+ (N ~ 4300) B0 J/y K* (N ~ 1900) B0 J/y Ks (N ~ 375) B0 J/y f (N ~ 400) Lb J/y L (N ~ 52) S/B improves with stronger lifetime cuts lxy/(lxy)>4.5

  8. B Hadron Lifetimes

  9. B Hadron Lifetimes: Expectations and Existing Data • In the naive quark spectator model, the decay is a 1  3 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 at the 3rd order in LQCD / mb • Goal  measure the ratios accurately

  10. B Meson Lifetimes from Exclusive BJ/X Decays; X= K+, K*, φ(CDF) Fit Method:Simultaneous fit of: M(B)signal fraction, def sidebands c(B)lifetime Signal Contribution: Background Parameterization:

  11. B Lifetimes; analysis details - CDF • L ~ 240 pb-1 • B candidate selection: • Substantial improvements in the analysis since 2003: optimized kinematic cuts to minimizestatsyst., B reflections excluded or carefully parametrized, final SVX alignment • 12 parameter fit, individual mass & proper decay length uncertainties, unbinned likelihod fit • Systematic uncertainties at `O(1mm) level D0 is using the same method, no new results since Summer 2003; new analyses of Bd, Bs, Lb lifetimes  being reviewed by EB

  12. Exclusive B Lifetimes; CDF results Lifetime Ratios(most systematic uncertainties 100 % correlated) • t (B+) / t (B0) = 1.080 ± 0.042 (tot.) t (Bs) / t (B0) = 0.890 ± 0.072 (tot.)

  13. B  V V Polarization Amplitudes • One of the Run II goals  measure the lifetime difference DGs between the CP eigenstates Bs,H(CP=-1) and Bs,L(CP=+1) • Angular analysis based on transversity variables, combined with a lifetime measurement allows one to separate the CP odd and CP evenfinal state • Time-integrated polarization amplitude analysis  a step towards aDGs measurement and a test of factorization (  weak decay matrix element a product of two independent hadronic currents) • CDF analysis uses: dimuon trigger data sets, L ~ 180 pb -1 Bd J/y K*0 (N ~ 1000)Bs J/y f (N ~ 180)

  14. B  V V Polarization Amplitudes • Three linear polarization states: J/ψ and φ (K*) polarization vectors: - longitudinal (0) to the B direction ; - transverse and parallel ( || ) , and - transverse to B and (┴ ) to each other • Angular distribution B  V V function of decay angles (cos QT,cosQK, FT) and transversity amplitudes A0, A|| , A┴ • Constraints: | A0 |2 + | A|||2+ | A┴ |2 =1, overall phase symmetry  A0 chosen positive real number • four degrees of freedom A0 = cos(Q1) A|| = sin(Q1) cos(Q2) exp(-if1) A┴ = sin(Q1) sin(Q2) exp(-if2) Transversity plane in the J/y rest frame B meson defines positive x-axis Kp (KK) plane defines (x,y) plane K (K+) +ve y momentum QT, FT polar & azimuthal angles of m+ QK helicity angle of K* ( f )

  15. Projection plots of the fitting results to the sideband subtracted angular distributions cos QT cos QT FT FT Bd Bs cos QK cos QK

  16. Preliminary Results - CDF • For B0dA0 = 0.792 ± 0.024 ± 0.016 A|| = ( 0.436 ± 0.057 ± 0.045 ) e (3.07 ± 0.40 ± 0.07 ) i A┴ = ( 0.428 ± 0.059 ± 0.063 ) e (0.11 ± 0.23 ± 0.06 ) I • For B0sA0 = 0.767 ± 0.045 ± 0.017 A|| = ( 0.424 ± 0.118 ± 0.013 ) e (2.11 ± 0.55 ± 0.29 ) I | A┴ | = 0.482 ± 0.104 ± 0.014  phase of A┴lost, Bs & Bs not distinguishable by their final state particles • B0d Comparison  Babar, Belle, CLEO, CDF Run I

  17. Argand Diagrams • dominant longitudinal polarization GL/G = |A0|2 • non-zero parity-odd fraction G┴ /G = |A ┴|2, (P-wave, CP= -1 for Bs) • arg(A||) ≈p for Bd , ≠ 0 or p for Bs (factorization ?)

  18. BsCP =+1 & CP = -1Lifetimes • B0sJ/ψφunknown mixture of CP =+1&CP = -1 states Γs = ( ΓL+ ΓH) / 2 ; ΔΓs = ΓH - ΓL CP=+1CP=-1 theory predicts s/s = - 0.13 ± 0.06 current limit |s/s|< 0.31  LEP Bs BRs In the case of untagged decay, the CP – specific terms evolve like: CP - even:( |A0|2 + |A|||2) exp( -ΓLt) CP - odd:|A┴|2 exp( -ΓHt) • Flavor specific final states (e.g. B0slDs ) measure: Γfs = Γs - (ΔΓs)2 / 2Γs + Ό ( (ΔΓs)3 / Γs 2 ) see: B-physics at the Tevatron Run II, p.361

  19. DGsfrom 3-D fits (mass, ct , transversityθT) The CP-evenand CP-odd components have distinctly different decay distributions in transversity variableθT : d(t)/d cosθT ∞ (|A0(t)|2 + |A||(t)|2) (1 + cos2θT) + |A┴(t)|2 2 sin2θT MC distributions for CP = +1 & CP= -1 for accepted events (an example) CP=+1 CP= -1

  20. An illustration: combining Bs J/yf with World Average cts for flavor-specific decays  DGs / Gs vs cts • Hypothetical • DG/G vs ct contour WA = Γfs≈Γs - (ΔΓs)2 / 2Γs ~1/Gs CDF & D0 results on DGs/Gs expected soon

  21. μ+ ν W+ b c B+/0 D0/*- u/d (B+)/(B0d ) from Semileptonic Decays spectator model: B+ and B0d lifetimes - same naïve spectator model (NL0) QCD(B+)/(B0d) - 1 X[ Hadronicmatrix elements from lattice QCD with coeff. ] (B+)/(B0d) = 1.047  0.016(NLO+had)  0.017(mbVcb,fB) 0.007( 1/mb) (e.g. M.Beneke, G.Buchalla, C.Greub, A.Lenz and U.Nierste, hep-ph/0202106)

  22. (B+)/(B0) from Semileptonic DecaysB  mD0(*)XNovel Analysis Technique (D0) • Measure directly lifetime ratio instead of individual lifetimes • Split D0Kp sample: presence / absence of D*  (D0 + slow p) • Make use of : D*  mainly from B0 D0 mainly from B+ - Group events into several bins of Visible Proper Decay Length - Measure r = N(mD*)/N(mD0) - In both cases fit D0 signal to extract N - use slow pion only to distinguish B0 from B+ (not in vertexing , K - factors etc  to avoid lifetime bias) • Account for feed-down from D** using PDG branching ratios and Monte Carlo

  23. μD0 μ+ K+ η π- D0 D*- LT B0 ν PV π- m , D0 K-p+&slow pselection • muonwith |h|<2 & PT > 2 GeV • K, p two tracks of opposite charge with PT>0.7GeV, |η|<2 in the same jet as the muon • Slow pionPT > 0.18 GeV • Lifetime and topological cuts • η acceptance from CFT • statistics decreases by 2.3 if |η|<1 cut applied to all particles

  24. +π± Dominated by B+ decays Dominated by B0 decays Semileptonic Bd data sample (D0) 109k inclusiveBm nD0candidates 25k BμνD* candidates

  25. 2% BS 12% B+ 86% B0 2% BS 16% B0 82% B+ Sample Composition From known branching ratios and reconstruction efficienciesfor a given channel • D* sample composed of • D0 sample composed of

  26. (B+)/(B0): fitting strategy • In each VPDL bin one example : VPDL bin [0.10 - 0.15 cm] • Fit D0 mass peak in both cases same way • Decreases systematics • N (D* ) is corrected for combinatorial bkg • in the D* mass window • Estimated from wrong sign Kpp • combinations  small correction • N ( D0 ) is corrected for D0‘s lost due to • D* mass window cut • Determine expected values ofrei (k)from • sample composition, channel dependent K-factors, efficiencies and resolutions • k – lifetime ratio, fit parameter Fit : Gaussian + 2nd order polynomial

  27. (B+)/(B0): Preliminary Result(D0) binned c2 fit of event ratios  (B+)/(B0) = 1.093  0.021 (stat)  0.022 (syst) one of the most precise measurements

  28. B0d Meson Oscillations • Use  Semileptonic B0d decays (D0, CDF - in progress) • Use  Fully reconstructed B0d decays (CDF, D0 – in progress)

  29. B0/B0 mixing • In SM Bd mixing is explained by box diagrams • Constrains Vtd CKM matrix element • Mixing frequency mdhas been measured with high precision at B factories (0.502  0.007 ps-1) • md measurement provides: • Benchmark the initial state flavor tagging for later use in Bs and ms measurements • at hadron colliders can also constrain more exotic models of b production e.g. light gluino & sbottom production (Berger et al., Phys.Rev.Lett.86,4231(2001))

  30. Reconstruct the final state, identify B flavor at decay • - Data sample:m triggers Bd m+D*(2010)- X( D*-D0p-,D0K+p- ) • -Find m+, D0, p- consistent with B decay • - Determine N(D*-) from mass difference M(D0p)- M(D0) distribtions • Identify B flavor at production • - several B-flavor tagging algorithms • - tagging efficiency:e = (Ncorr + Nwr) / (Ncorr + Nwr +Nnotag) • - tagging dilution:D = (Ncorr – Nwr) / (Ncorr + Nwr) • - figure of merit:e D2 • Measure Visible Proper Decay Length • Calculate observed asymmetry in bins of VPDL • Use PDG BRs & MC to calculate expected asymmetry(t) • Dmd & purity = (1+D)/2 free parameters of the fit Procedure for a B0d mixing measurement

  31. Flavor Tagging algorithms from Gomez-Ceballos OST (Opposite Side Tagging): Opposite side Same side JETQ: sign of the weighted average charge of opposite B-Jet SLT: identify the soft lepton from semileptonic decay of opposite B Opposite Side K: due to bcs it is more likely that a B meson will contain in final state a K+ than a K-(CDF) • SST (Same Side Tagging): • SS pion T: B0 is likely to be accompanied by a +from fragmentation • SS Kaon T: Bs is likely to be accompanied by a K+ from fragmentation (CDF)

  32. 64 D* 80 D*  146 D* 58 D* B0d oscillation from semileptonic decaysOpposite Side Muon Tagging (D0) D0 uses25kBm D*X, D*D0 pcandidates to measure md: • e.g. First bin VPDL = [0.0 - 0.025 cm] non-osc osc • e.g. Last bin VPDL = [0.125 - 0.250 cm] non-osc OSC B0 Final state: Not oscillated: QmOS x QmSS < 0 Oscillated: QmOS x QmSS> 0

  33. B0  B0/B0 Mixing Results: OS muon tagging • Tagging procedure • opposite side muon • muon pT > 2.5 GeV/c • cos Df(m, B) < 0.5 • Fit procedure • Binned c2 fit Preliminary results: md=0.5060.055(stat)0.049(syst) ps-1 Tagging efficiency: 4.8 ± 0.2 % Tagging purity: 73.0 ± 2.1 % • One of the best measurements at a hadron collider • Good prospects for improving accuracy • work in progress to decrease systematic uncertainty (mass fit) • use other tagging methods • add more D0 decay channels

  34. B0 Oscillations Using Same-Side Tagging (CDF) • L ~ 270 pb-1 • Use fully reconstructed ( N ~ 5900 ) : B0 J/y K*0 (J/y  m+ m-, K*0  K+p-) B0 D-p+ (D-  K+p-p-)  track trigg • Use B+ control samples ( N ~ 7800) : B+ J/y K+ (J/y  m+ m- ) __ __ B+ D0p+ (D0  K+p-) • Use same side tagging (SST) based on expected flavor-charge correlation between the B meson and charged tracks in its vicinity • Tagging parameters e(%) D(%) eD2(%) ------------------------------------------------ B+ 62.7 ± 0.7 21.2 ± 2.0 2.8 ± 0.5 (stat) B0 63.0 ± 0.6 12.4 ± 3.3 1.0 ± 0.5 (stat)

  35. Results (CDF) • Combined fit of J/y K*0 & D-p+ channels: D m d = 0.55 ± 0.10(stat.) ± 0.01(syst.) ps-1 • Systematic errors for D m d (mass fitting: 0.008 ps-1; ct resolution: 0.009 ps-1) • CDF Run I  Dmd (all methods) =0.495 ± 0.026 ± 0.025 ps-1

  36. Summary - lifetimes • New B meson lifetime measurements fromexclusive B J/ Xchannels by CDF • Measurement of B+/B0d lifetime ratio from semileptonic B decays - a novel analysis technique (D0) ] • Results competitive with B-factories, expect 1% ratio precision (2 fb-1) • Measurement of polarization amplitudes ofBdJ/yK* & B0sJ/yf • Measurement of s/sin progress , expect 5% precision (2 fb-1)

  37. Summary – B0d Oscillations • New measurements of B0d Oscillations using: - semileptonic decays; Opposite-Side m tagging (D0) • md=0.5060.055(stat)0.049(syst) ps-1 - B0 J/y K*0, D-p+ decays, Same-Side p tagging (CDF) • md=0.550.10(stat)0.01(syst) ps-1 World average: md=0.5020.007 ps-1 • Work in progress in both experiments: semileptonic/exclusive channels, other tagging methods, more D0 decay channels etc

  38. BACKUP SLIDES

  39. Semileptonic BS m nDsXsamplesFind: lepton + Ds f p ; f K+K-;lepton`s charge opp. to Ds CDF: lepton+high IP track trig.; better mass resolution & S/B, < events Work in progress to measure:Bs/Bd lifetime ratio; Bs mixing Lifetime measurement provides valuable constraint on DGs

  40. D0 muon trigger rates vs luminosity • CTT reduces the single muon trigger rate by ~3 for Pt>3 GeV • Single muon trigger is prescaled at high luminosities • Current total trigger bandwidth: 1500 Hz / 800 Hz / 60 Hz @ L1/L2/L3 - Single muons : 120 Hz / 100 Hz / 50 Hz @ L1/L2/L3 at 4 x 10 31 cm-2sec-1 - Di-muons : 50 Hz / 15 Hz / 4 Hz @ L1/L2/L3 at 4 x 10 31 cm-2sec-1

  41. Semileptonic Sample Composition Branching rates from PDG values for inclusive and exclusive measurements: Notice: : D* decays dominate both D0 and D* samples

  42. K-factors • K-factors take into account not reconstructed particles • Production B→D*μνX dominates both for D* and D0 samples • K-factors are computed as: K= PT(μD0) /PT(B), even for D*- sample • K-factors are the same for B0→D*-μνX and B+→D*0μνX decays • Reduced systematics • 4 groups of K-factors • B→D*μ • B0→D*-μν • B+→D*0μν • B→D0μ • B+→D0μν • B→D**μ→D0μ • No D*- reconstructed • B→D**μ→D*-μ

  43. Expected Ratio rei To calculate expected ratio in each VPDL bin • Sort decay channels between D0 and D* samples • For given decay channel determine the probability for B to have certain Visible Proper Decay Length according to • Lifetime • K-factor which takes into account not reconstructed particles • Resolution • Efficiency • Make a sum for each sample according to the branching rates • Integrate over the VPDL bin to get the number of events • Take the ratio

  44. Fitting Procedure expected measured

  45. Oscillations in D* and D0 samples DØ RunII Preliminary • Expect to see oscillations • Level is offset by B+ contribution • Expect to see no oscillations • Some variation from oscillations due to B0 contribution into sample composition

  46. Opposite Side (OS) Muon Tagging OS muon tagging ← Good signal in muon system

  47. + - Fitting Procedure

  48. (B+)/(B0): Comparison with other experiments New DØ result (average not updated, plot not official or approved by HFAG) one of the most precise measurements

  49. (B+)/(B0): Preliminary Result(D0) Main systematic errors: binned c2 fit of event ratios (B+)/(B0) = 1.093  0.021 (stat)  0.022 (syst)

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