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Recent B Physics Results at D Ø

Recent B Physics Results at D Ø. Bill Lee Florida State University 18 February 2004. X(3872) B Lifetime and Mixing B s  m + m - Search. The D Ø Run 2 Detector. SMT. X(3872) at D0. Using 200 pb -1 of DATA collected April 2002 – September 2003, we look for X(3872)  J/ p + p -

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Recent B Physics Results at D Ø

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  1. Recent B Physics Results at DØ Bill Lee Florida State University 18 February 2004 • X(3872) • B Lifetime and Mixing • Bs m+m- Search

  2. The DØ Run 2 Detector SMT

  3. X(3872) at D0 • Using 200 pb-1 of DATA collected April 2002 – September 2003, we look for X(3872)  J/ p+p- • Silicon hit > 1 • num tracks < 100 • pT(J/) > 4 GeV/c • 2.8 < M(m+m-) < 3.4 GeV/c2 • pT() > 0.4 GeV/c • ’s within same cone as J/ • M(+ -) > 0.52 GeV/c2 • M(m+m- + -) -M(m+m-) < 1.0 GeV/c2 • 2 (m+m- + - - vertex) < 16 • |zvertex| < 35 cm 4.4s effect 300  61 X(3872) candidates DM = 0.7684  0.0035 (stat)  0.0039 (sys) GeV/ c2

  4. Properties of X(3872) • Are the production characteristics similar to the (2S)? • To compare, the data was binned for several different variables: decay-length, isolation, h (pseudo-rapidity), pT, and helicity of (+ -)

  5. X(3872) and (2S) comparison Yield per given cut / Total Yield Within the current statistical uncertainties, the production of X(3872) has similar behavior as the (2S), but an exotic meson could also behave similarly.

  6. Is X(3872) charmonia? • If the charged analog X+J/p+p0was observed,then cc hypothesis could be ruled out • While observing radiative decays Xc1 would favor cc hypothesis • Both of these would require DØ to identify low energy p0 and  (work in progress) - -

  7. Measuring Lifetime using BJ/ X, J/+- Use J/+- for tagging, vertex constraint, pT determination: • Clean signal • Large statistics • Good vertex resolution • Good momenta resolution • Large prompt J/ contamination • Need Pt correction factor from MC 114pb-1 (2s) Signal = 8.22K events Mass = 3.668 ± 0.002 GeV/c2  = 0.071 ± 0.002 GeV/c2 J/ Signal = 290.3k events Mass = 3.0718±0.0002 GeV/c2  = 0.0741±0.0002 GeV/c2

  8. B Lifetime from Inclusive BJ/+X B J/ X Ldt114 pb-1 F: correction factor to use the pT(J/ ) to estimate the momentum of the B to find proper time. Obtained from Monte Carlo  = 1.564  0.014 ps (PDG) J/ from B’s = 18%  = 1.562  0.013  0.045 ps Correction factor leads to the major systematic error

  9. Bd,s Masses (J/ + K0*,,K0s) For CP and Lifetime studies

  10. B± Lifetime from B±J/K± Ldt114 pb-1 Fully reconstructedNo Correction Factor! <B±>=1.65±0.083(stat)±0.123(syst) ps <B±>=1.671±0.018 ps (PDG)

  11. Bd,s Lifetimes from BJ/+K0*, Similar kinematicsSome systematic errors can be cancelled in ratio! Signal: 105±19 Signal: 69±13 Ldt114 pb-1 Bd=1.51+0.19(stat) ± 0.20(syst) ps -0.17 PDG: Bd = 1.537 ± 0.015 ps Bs=1.19+0.19(stat) ± 0.14(syst) ps -0.16 PDG: Bs = 1.461 ± 0.057 ps Bs/Bd=0.79 ± 0.14 PDG: Bs/Bd = 0.95 ± 0.038

  12. Large B Semileptonic Sample • Muon: • Pt > 2 GeV/c • Charged tracks: • pT > 0.7-1 GeV/c • Secondary Vertex • Lxy / L > 4 • cos((L,PD))>0.95

  13. B Lifetime from Semileptonic Decays B D0X We are able to measure Lifetime Ldt12 pb-1 c=LxyMbK/Pt(D+) K = Pt(D+) /PtB (from MC) B=1.460 ± 0.083 (stat) ps B=1.564 ± 0.014 ps (PDG) We will use this for mixing studies

  14. Mixing: Flavor tagging • In order to study Bs mixing we will need • final state reconstruction • ability to measure B decay lengths • the ability to tag the flavor of the B at production and decay. • We can use flavor-specific decays to get the flavor of the B at decay. To get the flavor of the B at production we use three methods: - Soft-lepton tags - Jet Charge tag - Same Side tagging • We can test these tools using our B+ data sample

  15. Flavour Tagging results DØ RunII Preliminary Muon DATA, we will also use electrons Performance with B0/Bs is under study

  16. Search for Bs m+m- SM: Br(Bs m+m- ) = 3.7 10-9 Some SUSY tan(b) models can enhance the signal. MC Dimuon spectrum Ldt100 pb-1 No Excess Seen. Br(Bs m+m- ) < 1.6  10-6 at 90% CL

  17. Summary • DØ has observed the X(3872) particle in 200 pb-1 data • We have reprocessed  200 pb-1 of data to better improve our analyses. • D0 will be able to study Bs mixing • Tevatron is performing well. • D0 recorded 9.4 pb-1 last week. • Lots of data. • Many more interesting results coming very soon!

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