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Published on June 18, 2007

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B Lifetime Results from CDF and D0:  B Lifetime Results from CDF and D0 Daria Zieminska Indiana University (D0 Collaboration) Beauty 2003 See also recent CDF talks: Sinead Farrington, EPS, July 03 : Kevin Pitts, LP03, August 03 Outline:  Outline Introduction – expectations Tevatron Run II – B triggers and data Inclusive B  J/ψ + X Exclusive B  J/ψ + X channels - B+  J/ψ + K+ - B0d  J/ψ + K* - B0s  J/ψ + φ - Λ b  J/ψ + Λ Semileptonic B Decays B Hadron Lifetimes: Expectations and Existing Data:  B Hadron Lifetimes: Expectations and Existing Data Heavy Quark Expansion Experiment τ(B+)/τ(Bd) = 1.06± 0.02 1.074± 0.014 τ(Bs)/τ(Bd) = 1.00± 0.01 0.948 ± 0.038 ΔΓs / Γs ≈ 0.1 andlt;0.54 (CL=95%) τ(Λb)/τ(Bd) = 0.90 ± 0.05 0.796 ± 0.052 The main goal is to measure the ratios accurately. B Physics at the Tevatron:  B Physics at the Tevatron Pros Large BB cross section: - ~ 100 µbarn total - ~ 3-5 µbarn 'reconstructible' At 4 x 1031cm-2s-1  ~150 Hz of 'reconstructible' B’s All B species produced Tevatron – world best source of Bs and Λb Production is incoherent - reconstruction of both Bs not needed Cons Large background - B cross section ~10-3 total inelastic - special triggers (leptons, displaced tracks) - combinatorics in reconstruction Typical kinematic cuts: - pT(µ) andgt; 1.5 GeV/c for µ’s from J/ψ - pT(B) andgt; 5 (6) GeV/c - Run II at the Tevatron data available by September shutdown:  Run II at the Tevatron data available by September shutdown Analyses presented here based on: - CDF 138 pb -1 (di-µ trig.); - D0 114 pb -1 (di-µ trig.); 12 pb -1 (single-µ trig.); Triggers for B Lifetime Studies:  Triggers for B Lifetime Studies CDF Di-muon (J/ψ) pT(µ) andgt; 1.5 GeV/c , |η (µ) | andlt; 0.7 l + displaced track pT(e/µ) andgt; 4 GeV/c pT(trk) andgt; 2 GeV/c , 120 µm andlt; d 0 (trk) andlt; 1 mm Two displaced tracks pT(trk) andgt; 2 GeV/c , 120 µm andlt; d 0 (trk) andlt; 1 mm D0 Di-muon, pT(µ) andgt; 3 GeV/c, |η (µ) | andlt; 2.2 (unprescaled) pT(µ) andgt; 1.5 GeV/c, |η (µ) | andlt; 2.2 (Lum. dependent prescale) Single µ, pT (µ) andgt; 3-5 GeV/c, |η (µ) | andlt; 2.2 (Lum. dependent prescale) Displaced tracks – after shutdown List of Analysis Techniques:  List of Analysis Techniques 1D: bkg template from sideband (variations: allow LSB ≠ RSB) 2D: simultaneous fit to (mass, cτ), free bkg parameters Inclusive B  J/ψ + X Lifetime (D0):  Inclusive B  J/ψ + X Lifetime (D0) Measure: λψ = L xy Mψ /pψT Need: λB = L xy MB /pBT Correction factor: F = λψ / λB = Mψ pBT / MB pψT MC provides mean F(pψT) in slices of pψT  D0 parametrization of F(pψT) 300k J/ψ’s Inclusive B  J/ψ + X Lifetime (D0)Fitting technique:  Inclusive B  J/ψ + X Lifetime (D0) Fitting technique Two steps: - fit λ distribution of the sidebands to get the shape of the background. The bkg parametrization gbkg(λ): Prompt  taken from MC (Gaussian plus exponential tails) (λandgt;0) and (λandlt;0) exponentials - fit λ distribution in the signal region allowing for: bkg distribution gbkg(λ) Prompt J/ψ (similar to prompt bkg) Exponential decay convoluted with Gaussian (bJ/ψ +X) Inclusive B  J/ψ + X Lifetime D0 and CDF results:  Inclusive B  J/ψ + X Lifetime D0 and CDF results D0 (114 pb -1 ) τ = 1.562±0.013(stat)±0.045(syst) ps main syst uncertainties: correction factor: 1.6 % MC bias: 1.9 %  82% J/ψ’s prompt CDF (18 pb -1 , 2002) τ = 1.526±0.034(stat)±0.035(syst) ps main syst uncertainties: correction factor: 1.1 % resolution function: 1.5 % bkg parametrization: 1.1 %  83% J/ψ’s prompt B+  J/ψ + K+ Lifetime (D0)Data and Fitting technique:  B+  J/ψ + K+ Lifetime (D0) Data and Fitting technique 1D fit  steps: - Fit λ distribution of the right sideband Prompt andamp; (λandgt;0) and (λandlt;0) exponentials - Fit λ distribution in the left sideband with an extra term for feeddown from multibody B decay channels - Fit the signal region Norm. of feeddown = 0.12 ± 0.01 (MC) B+J/ψ K+ ; Results D0 CDF:  B+J/ψ K+ ; Results D0 CDF Slide13:  Fit Method: Simultaneous fit of M(B)  signal fraction, define sidebands c(B)  lifetime Background Parameterisation: Signal Contribution: Exclusive BJ/X Lifetimes; X= K+, K*, φ (CDF) Bs  J/ψ φ with Bd  J/ψ K* as a control channelCDF D0:  Bs  J/ψ φ with Bd  J/ψ K* as a control channel CDF D0 138 pb-1 of data 2D fit (Mass, cτ) Signal events: 120 ± 13 pT(B) andgt; 6 .5 GeV/c pT(φ) andgt; 2 GeV/c run averaged beam spot: 33µm track impact parameter resol: 35µm 114 pb-1 of data 2D fit (Mass, cτ) Signal events: 69 ± 14 pT(B) andgt; 6 GeV/c pT(φ) andgt; 2 GeV/c pT(K) andgt; 1 GeV/c event by event PV Lxy resolution ≈ 40 µm B0s  J/ψ + φ ; Data (D0) Decay Length resolution :  B0s  J/ψ + φ ; Data (D0) Decay Length resolution Dots – B Line – J/ B0s  J/ψ + φ ; DataD0 CDF:  B0s  J/ψ + φ ; Data D0 CDF 69±14 cand. 54±10 cand. B0d  J/ψ + K* ; DataD0 CDF:  B0d  J/ψ + K* ; Data D0 CDF B0s  J/ψ + φ ; Fit resultsD0 CDF:  B0s  J/ψ + φ ; Fit results D0 CDF B0d  J/ψ + K* ; Fit resultsD0 CDF:  B0d  J/ψ + K* ; Fit results D0 CDF Slide20:  bJ/  Lifetime and Crosscheck (CDF) CONTROL SAMPLE BdJ/ψK0 Bs and Λb Lifetimes - Summary:  Bs and Λb Lifetimes - Summary Bs CP =+1 & CP = -1 Lifetimes :  Bs CP =+1 andamp; CP = -1 Lifetimes B0sJ/ψ φ unknown mixture of CP =+1 andamp; CP = -1 states Standard Model predicts s/s ~ 0.1 Γs = ( ΓLight + ΓHeavy)/2 ; ΔΓs = ΓLight - ΓHeavy CP=+1 CP=-1 In the case of untagged decay, the CP – specific terms evolve like: CP - even: ( |A0(0)|2 + |A||(0)|2 ) exp( -ΓLightt) CP - odd: |A┴(0)|2 exp( -ΓHeavyt) Flavor specific final states (e.g. B0slDs ) provide: Γfs = Γs - (ΔΓs)2 / 2Γs + Ό ( (ΔΓs)3 / Γs 2 ) Bs Lifetimes, transversity variable θT:  Bs Lifetimes, transversity variable θT The CP-even and CP-odd components have distinctly different decay distributions. The distribution in transversity variable θT and its time evolution is: d(t)/d cosθT ∞ (|A0(t)|2 + |A||(t)|2) (1 + cos2θT) + |A┴(t)|2 2 sin2θT 3 linear polarization states: J/ψ and φ polarization vectors: longitudinal (0) to the B direction of motion; transverse and parallel (||) and (┴ ) to each other Semileptonic Lifetimes:  Semileptonic Lifetimes The goal is to extract the Bs and Λb lifetimes using lepton + D0 as a control channel reconstruct the D decay near lepton B decay not fully reconstructed  extract the boost factor from MC: extract lifetime from decay length CDF: lepton + displaced track trigger small statistical uncertainty D0: single muon trigger (prescaled at high luminosity) Semileptonic Lifetimes (D0) B  D0 µ X benchmark analysis :  Semileptonic Lifetimes (D0) B  D0 µ X benchmark analysis 1D Analysis Factor K = pT(D0+µ)/pT(B) from MC (generator level, confirmed with reco’ed tracks) Bkg model: - Prompt andamp; - +ve exp,-ve exp andamp; - additional +ve (left side) Resolution: double Gaussian Results  see next page Semileptonic Lifetimes :  Semileptonic Lifetimes D0 results for the B  D0 µ X benchmark analysis τ =1.46 ± 0.083(stat) ps - to be compared with τ =1.60 ± 0.02 ps  WA for this channel Summary:  Summary Lifetime measurements for inclusive B J/ X decays and for exclusive B J/ X channels by both CDF and D0: Measurements of polarization states in B0s decay and of s/s  in progress Lepton + displaced vertex trigger has been implemented at CDF for the first time expects high statistical accuracy for B0s and Lb lifetime Benchmark measurement of B  D0 µ X (D0) Backup slides:  Backup slides Bs Lifetime Summary of existing measurements:  Bs Lifetime Summary of existing measurements Flavor-specific final states: Γfs = Γs - (ΔΓs)2 / 2Γs + Ό ( (ΔΓs)3 / Γs 2 ) Γfs ≈ Γs = ( ΓLight + ΓHeavy)/2 CP=+1 CP=-1 ΔΓs = ΓLight - ΓHeavy Unknown mixture of ΓLight , ΓHeavy (predominantly CP = +1) Systematic uncertainties (CDF):  Systematic uncertainties (CDF) Systematic uncertainties (D0):  Systematic uncertainties (D0)

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