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B Production and Decay at D Ø

B Production and Decay at D Ø. Brad Abbott University of Oklahoma BEACH 2004 June 28-July 3. B physics at D Ø. Will be presenting latest results on: D** B** B s  m + m -  (1S) production X(3872) Keys to D Ø B physics program Muon system and trigger

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B Production and Decay at D Ø

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  1. B Production and Decay at DØ Brad Abbott University of Oklahoma BEACH 2004 June 28-July 3

  2. B physics at DØ • Will be presenting latest results on: • D** • B** • Bsm+ m- • (1S) production • X(3872) • Keys to DØ B physics program • Muon system and trigger • Silicon vertex detector and fiber tracker L= 115 – 250 pb-1

  3. SMT SMT SMT Muon System and Tracker • New forward muon system with |h|<2 and good shielding • 4-layer Silicon and 8 doublet-layer Fiber Trackers in 2 T magnetic field

  4. Observation of B m n D** X • D** are orbitally excited D meson states • In heavy quark limit • Two narrow states (D-wave) • Two broad states(S-wave) • Search for narrow states via • D01(2420)  D*+p- • D*02(2460) D*+ p-

  5. D0 sample • D10 and D2*0 observed in several experiments, most recently by BaBar/Belle in B-D**0p- • DØ is studying D10 and D2*0 in B semileptonic decays • Start with B m D0 X (D0 Kp)

  6. D* sample • Add a pion (charge correlated with the muon) with PT>0.18 GeV

  7. D** • Measure invariant mass of D*-p+ system • See merged D10(2420) and D2*0 (2460) Wrong sign combinations

  8. Interference effects Two interfering Breit-Wigner D** states with mass/width as measured by Belle (no resolution effects included) Work in progress to extract separate amplitude for each state and relative phase of interference.

  9. Branching ratio • Take experimentally measured number of D10 and D2*0 : N(D1)+N(D2*)=523  40 • Measure branching ratio of B m n D**(narrow) X, normalizing to known branching ratio (B D*+m n X) • Br(B {D10,D2*0} m n X • Br({D10,D2*0}  D*+p-) = 0.280  0.021(stat) ± 0.088 (sys) % • Compare to LEP measurement of total D** Br (B D*+p m n X) = (0.48  0.10)% • ~ half the rate through narrow states

  10. Future measurements = 0.4-0.7 predicted by HQET World average =0.4 ± 0.15 • DØ can measure: • R • Br(B  m D1X ) • Br(B m D*2 X) • Interference effects • Helicity

  11. B** • Heavy quark symmetry predicts 4 B*J states JP = 0+, 1+ , 1+ , 2+ • Parity and angular momentum require B*J to decay to B* p or Bp • B** provide a good test of heavy quark symmetry • Many properties of the B** unknown • Large B cross section at Tevatron allows for precise measurements with large statistics

  12. B** 115 pb-1 • Search for B**dB+p- B+J/Y K+ • Allows one to charge correlate the pion and the B to reduce combinatoric background PDG Average 5.698  0.008 GeV

  13. Additional Channels • Are adding in more decays to increase statistics • B**+ Bdp+ • BdJ/Y K* • BdJ/Y KS • With increased statistics should be able to resolve the narrow B** states.

  14. Bd,sm+ m- • Forbidden at Tree Level in SM Theoretical predictions Experimental limits at 90% CL

  15. Bsm+ m- in SUSY(Two Higgs-Doublet Model) • BR depends only on charged Higgs mass and tan b • BR increases as tan4b(tan6b) in 2HDM (MSSM) • R parity violating models can give tree level contributions

  16. Dimuon Data sample

  17. Cut optimization • Signal box is blinded • Use a random grid search optimizing the ratio (Following proposal from G. Punzi physics/0308063 Test of hypothesis and limits) emm= reconstruction efficiency of signal MC B= expected background extrapolated from sidebands a = number of sigmas corresponding to confidence level (set to 2 for this analysis, corresponding to ~ 95% CL

  18. Discriminating variables • Isolation of the muon pair • Opening angle between momentum vector of mm pair and vector pointing from primary vertex to mm vertex • Decay length 180 pb-1 Box not opened yet

  19. Expected upper limit • Since box not opened, calculate expected upper limit • Expected signal normalized to B+J/YK+ • Expect 7.3 ± 1.8 background events in signal region • Current expected limit using Feldman-Cousins: Br(Bsm+m-) < 1.0 10-6 @ 95% CL (stat + sys) Reoptimization still in progress. Further improvements expected

  20. (1S) Production • Measuring the (1S) production cross section provides a test of our understanding of the production mechanism of heavy quarks • Extend measurement of (1S) cross section to rapidities of 1.8 • Color octet model predicts an increase in transverse polarization with increasing PT (Measurements so far are inconclusive)

  21. Analysis • Measure the (1S) cross-section as a function of PT in three rapidity regions 0< |y| <0.6 0.6<|y|<1.2 1.2<|y|<1.8 Signal fit to 3 Gaussians (1S), (2S), (3S) Background: 3rd order polynomial m((2/3S) = m((1S) + Dmpdg((2/3S)- (1S)) s((2/3S) = s((1S) + m (2/3S)/m((1S))* s((1S)) 5 parameters: m,s(1S) Number of (1S), (2S), (3S)

  22. Normalized cross section 159 pb-1

  23. Normalized Cross section

  24. Normalized cross section • Normalized cross section shows little dependence on rapidity • Good agreement with published results • Absolute cross section nearly ready • Next: Polarization measurement

  25. X(3872)  J/Yp+p- • First observed by Belle B+ K+ X(3872) decays • Signal confirmed by CDF, DØ and BaBar • Nature of X(3872) unknown • Theories include: • Another charmonium state • D D* molecular state • Since the X(3872) lies very close in mass to the Ψ(2S) charmonium state, and has a common decay mode (X J/Y p+ p- ), we compare production and decay properties of these two states through this decay mode

  26. X(3872) 230 pb-1 • DM=774.9 ± 3.1 (stat)  3.0 (sys) MeV • 522 ± 100 X candidates • Significance = 5.2

  27. Separate data into different regions • Compare Y(2S) yield to X yield in different regions • Study production and decay characteristics

  28. Compare • a) PT > 15 GeV • b) |y| <1 • c) |cos(Qp)| < 0.4 • d) decay length < 0.01 cm • e) isolation=1 • f) |cos (Qm)| < 0.4 (Qp : boost one of the pions and the X(3872) into dipion rest frame. Qp is the angle between them) • To within uncertainties, production of X(3872) found to be consistent with the production of the Y(2S) I.e producted both directy and via B decays, • Future: look for radiative decays and charge analog of X Submitted to PRL: hep-ex/0405004

  29. Summary • Observation of B m n D** X • Observation of B** • Sensitivity to Bs  m+ m- • Normalized Upsilon(1S) Cross section • Observation of X(3872) • Many new analyses on the way

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