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Recent B physics at D Ø

Recent B physics at D Ø

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Recent B physics at D Ø

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  1. Oklahoma Center for High Energy Physics OCHEP Recent B physics at DØ Brad Abbott University of Oklahoma Brad Abbott University of Oklahoma

  2. Overview • CP violation : • BsJ/yf • Bs Ds(*)Ds(*) • B+  J/y K+ • Latest Bs mixing results • Spectroscopy: • Bc mass • Bc lifetime • Upsilon Polarization } More detail No time for details (apologies) Brad Abbott University of Oklahoma

  3. B physics at the Tevatron Produce heavier states not currently accessible anywhere else: Bs0,Bc,B**,Bs**,Lb,Sb,Xb,…. • Complementary to B factories at (4S) • Huge production rates s(pp bb) ≈ 150 mb • But also huge backgrounds • Need to design specific B physics triggers Triggers strongly affect what physics can be done Currently in the realm of precision measurements. Can be competitive with B factories in some B+ and Bd decays Brad Abbott University of Oklahoma

  4. Collecting data from pp collisions at √s = 1.96 TeV Tevatron running with peak luminosities of 300 x 10 cm-2 s-1 (up to 10 interactions/crossing) Total delivered ~ 4.2 fb-1, recorded ~ 3.7 fb-1 May record month: Tevatron delivered 221 pb-1 DØ recorded 204 pb-1 (~ 100 pb-1 Run 1) Large angle coverage Single and dimuon triggers Changing solenoid/toroid polarity regularly Brad Abbott University of Oklahoma

  5. CP violation in BS decays • Trying to understand source of CP violation • Bs system good place to search for new physics • B factories have shown that large (> ~10%) contributions of new physics are excluded from tree level B+ and B0 decays • Bs decays much less constrained. • Current experiments do not exclude large phases from new physics • CP violation in Bs system is expected to be small in Standard Model. A large CP phase is a possible indication of new physics Brad Abbott University of Oklahoma

  6. Bs0–Bs0 Mixing Flavor eigenstates propagate according to the Schrodinger Eq. Diagonalizing gives two physically observed “Heavy” and “Light” mass eigenstates Observables Brad Abbott University of Oklahoma

  7. CP Violation in the Bs0 System How could new physics affect these phases? ~0.04 Measure the phase responsible for CP violation in Bs J/yf decays fsJ/yf≈ fsNP (if large) Brad Abbott University of Oklahoma

  8. CP Violation in Bs0→ J/ψΦ decays CP violation becomes observable in these decays due to the interference between the mixing and decay amplitudes. J/y + f is an admixture of states that are both CP(even) and CP(odd) Angular analysis is used to separate the CP components and measure the lifetimes of each component Flavor Tagging gives us useful information on the flavor of the produced Bs0 meson Brad Abbott University of Oklahoma

  9. Bs0 → J/ψΦ J/ψ and φ are vector particles and have definite angular distributions for CP-even and CP-odd final states. Bs → V1 + V2 (J/ψ + φ) Spin 0 → 1 + 1 ℓ = 0,1,2 Parameterized angular decay in the Transversity basis. Angular dependencies are described in terms of polarization amplitudes: A0: Both vectors longitudinally polarized (ℓ = 0,2)CP even A║: Transversely polarized and vectors parallel (ℓ = 0,2)CP even A┴: Transversely polarized and vectors perpendicular (ℓ = 1)CP odd Brad Abbott University of Oklahoma

  10. Angular Analysis φ rest frame J/ψ rest frame Brad Abbott University of Oklahoma

  11. ΔΓs CP Conservation, φs = 0 (Stat + syst)‏ Brad Abbott University of Oklahoma

  12. Sensitivity to φs After flavor tagging No Flavor tagging 90% CL = 68% CL Probability of fluctuation from SM to observation is 6.6% (1.8 s) Four-fold ambiguity reduces to two-fold after applying flavor tagging. Brad Abbott University of Oklahoma

  13. Angular Fit Projections Brad Abbott University of Oklahoma

  14. Results with Flavor Tagging (d1,d2 CP conserving strong phases) Brad Abbott University of Oklahoma

  15. Why Bs→Ds(*)Ds(*)? • Br(Bs→Ds(*)Ds(*) ): • theory based analysis: CP even (5~30%) • comparable error band • consistent with theory • untagged: efficiency, purity, acceptance • simpler measurement Flavor Specific: Bs Dsmn Direct: Bs J/yf Theory prediction ΔΓs = 0.096 ± 0.039 (J. HEP. 0706, 072) Brad Abbott University of Oklahoma

  16. Theory of Br & ΔΓ • Ds(*)Ds(*) ground states Ds(*) since cannot distinguish Ds from Ds* undetected particle in Ds*  Dsg/p0 + heavy quark (mc→ ∞) + factorization (2mc→ mb) (Phys. Lett. B 316, 567 (1993)) = In SM = (fs=0) Brad Abbott University of Oklahoma

  17. Br(Bs→Ds(*)Ds(*)) • Sampling: Dsφμvs. Dsμ m(φπ) Ds D± N=28,680±288 trigger • Normalizing:DsφμtoDsμ trigger Brad Abbott University of Oklahoma

  18. Correlation Ds-Ds 2-D Unbinned Loglikelihood Fit Ds(φ1π) vs.φ(K3K4) Bkg-Sig m(φ1π) Sig-Sig Sig-Bkg Bkg-Bkg trigger m(K3K4) Brad Abbott University of Oklahoma

  19. Correlation Ds-Ds 2-D Unbinned Loglikelihood Fit Ds(φ1π) vs. φ(K3K4) Ds(φ1π) φ(K3K4) trigger N(Dsfm)=31.0 ± 9.4 Significance of 3.7 s Brad Abbott University of Oklahoma

  20. Peaking backgrounds • Bs Ds(*)Ds(*) X ~ 0 % contribution • B±,0 Ds(*) Ds(*) KX 5 ± 2% (m(Dsfm)>4.3 GeV) • cc  Ds(*)fmX 2 ± 1% (lifetime cut) • Bs  Ds(*)mnf 0 ± 3% (m(fm)<1.85 GeV) Peaking backgrounds small Brad Abbott University of Oklahoma

  21. Sample Composition Mi : total # of events for channel i nj : total # of events in j region fi,j : fraction for channel i in region j a: Bs→Ds(*)Ds(*) b: B±,0→Ds(*)Ds(*)KX c: Bs→Ds(*)µnφ pure signal events: N(Bs0→ Ds(*) Ds(*)) = 27.5 ± 9.8 Brad Abbott University of Oklahoma

  22. Systematics • poor precision of branching ratios ( ≥ 60 %) • large room for further improvement • trigger efficiency model dependent calculation • uncertainty by ccbar contamination is small Brad Abbott University of Oklahoma

  23. Results • Br(Bs Ds(*)Ds (*))=0.042 ± 0.015 (stat) ± 0.017 (sys) DGs/Gs=0.088 ± 0.030(stat) ± 0.036(sys) Brad Abbott University of Oklahoma

  24. Direct CP Violation • SM predicts ~ 1% CP asymmetry for B+ J/y K+ • Frequent solenoid and toroid polarity changes allow a control of charge asymmetry systematic uncertainties • Correct for K+/K- asymmetry ACP(B+ J/y K+) = +0.0075 ± 0.0061 ± .0027 hep-ex: 0802.3299 Factor of 2 better than current world average Brad Abbott University of Oklahoma

  25. Update on Bs mixing Example from semileptonic decay Opposite Side Reconstructed Side X μ+,e+ B μ(e) LT π- D-S φ ν K- K+ • Select Bs candidate Look on the decay mode BsνlDs(φπ) • For each Bs candidate • BS flavor at decay time from lepton sign at the reconstructed side • Transverse length LT and its error • Transverse momentum PT(Bs) (use PT(Dsl)) • B-hadron flavor at the opposite side (indicates BS flavor at production time) Brad Abbott University of Oklahoma

  26. Amplitude Method • If mixing signal with Δms, amplitude A=1 otherwise A=0 • Scan Δms, for each value find A ± DA • Plot A for each value of Dms Brad Abbott University of Oklahoma

  27. Bs mixing results 2.9 s significance Dms=18.53 ± .093 (stat) ± 0.30 (sys) ps-1 0.2018 ±.0053 (exp) ± .0010 (Dmd) + .0078 - .0058 (x) Brad Abbott University of Oklahoma

  28. Spectroscopy: Bc meson Mass • Bc contains two different heavy quarks (Unique) • Decays • via b quark: • Bc+ Bsp+, Bs l+n • via c quark • BcJ/yp+, J/y Ds+, J/y l+n • Annihilation • Bc l+n Accepted by PRL hep-ex 0802.4258 M(Bc+)=6300 ± 14 ± 5 MeV Brad Abbott University of Oklahoma

  29. Bc lifetime • Decays • via b quark: • Bc+ Bsp+, Bs l+n • via c quark • BcJ/yp+, J/y Ds+, J/y l+n • Annihilation • Bc l+n Simultaneous fit to mass Templates and lifetime models +0.039 + 0.039 ps t(Bc)= 0.444 -0.036 – 0.034 Most precise by a factor of 2 Theory (hep-ph/0308214) t(Bc)=0.48± 0.05 ps Submitted PRL hep-ex 0805.2614 Brad Abbott University of Oklahoma

  30. Upsilon polarization Non relativistic QCD predicts that the S-wave quarkonium should be transversely polarized at high PT Dimuon invariant mass fitted in bins of |cosq*| (q* angle of positive lepton in the quarkonium center of mass frame with respect to the momentum cf the decaying particle in the laboratory frame) Good agreement between data (points) and weighted MC(histogram) Brad Abbott University of Oklahoma 0.4 < |cos q*| < 0.5

  31. Upsilon polarization Define polarization a =(sT – 2 sL)/(sT + 2 sL) NRQCD CDF DØ Data Lower purple curve:Kt factorization model with Quark-spin conservation hypothesis Upper purple curve:Kt factorization model with Full quark-spin depolarization hypothesis Significant PT dependent longitudinal polarization for (1S) which is inconsistent with NRQCD predictions Submitted PRL hep-ex 0804.2799 Brad Abbott University of Oklahoma

  32. Conclusions • Tevatron doing very well • DØ continuing to collect high quality physics data • Producing precision measurements (World’s best) in a number of different areas • Continue to exploit large luminosities and large number of states produced at Tevatron Brad Abbott University of Oklahoma

  33. Backup Brad Abbott University of Oklahoma

  34. CP Violation in the Bs0 System Vts CKM Matrix SM accommodates CPV by introducing a single complex phase in the CKM matrix Bs0 unitary condition Im Vts >> Vub VtsVtb*/VcsVcb* Area of triangle proportional to level of CP violation VusVub*/VcsVcb* βs Re 1 Brad Abbott University of Oklahoma

  35. CP Violation in Bs0– Bs0 Mixing Matter Antimatter W b s Bs0 Bs0 u,c,t u,c,t b s W Interference Semileptonic asymmetry N(Bs0 → D--) vs N(Bs0 → Bs0 → D--)‏ Brad Abbott University of Oklahoma

  36. Differential Decay Rate and Amplitudes Brad Abbott University of Oklahoma

  37. Polarization Amplitudes Upper sign: Time evolution of pure Bs0 → J/ψΦ at t=0 Lower sign: Time evolution of pure Bs0 → J/ψΦ at t=0 Brad Abbott University of Oklahoma

  38. Polarization Amplitudes (no Flavor Tagging)‏ Assuming equal production rate of Bs0 and Bs0 Opposite terms vanish, but still sensitive to φs Brad Abbott University of Oklahoma

  39. Flavor Tagging Measurement of Bs0 or Bs0 flavor at production b quarks produced in pairs εD2 for Bs0 → J/ψφ is 4 – 5 % Brad Abbott University of Oklahoma

  40. Efficiency Model • Different muon property • Bs0→Ds(*)μν: primary • Bs0→Ds(*)Ds(*)(Ds →φμν): secondary ─ Bs0→Ds(*)μν ─ Bs0→Ds(*)Ds(*) D0 RunII Preliminary (2.8 fb-1) Dsμ sample data MC Universal Trigger Efficiency Curve Normalized signal yield for data and model Brad Abbott University of Oklahoma DO Collaboration Meeting May 22, 2008

  41. DMs Brad Abbott University of Oklahoma