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Heavy Flavour Production at D Ø

Heavy Flavour Production at D Ø. Daniela Bauer. Imperial College London. for the D Ø collaboration. Hadron Collider Physics 2002. Karlsruhe 30/9-4/10 2002. D Ø Run II programme. production cross section and angular correlations. J/ ψ cross section and polarization.

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Heavy Flavour Production at D Ø

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  1. Heavy Flavour Production at DØ Daniela Bauer Imperial College London for the DØ collaboration Hadron Collider Physics 2002 Karlsruhe 30/9-4/10 2002

  2. DØ Run II programme • production cross section and angular • correlations • J/ψ cross section and polarization • Y cross section • Production and spectroscopy of B-mesons and • baryons • Lifetimes • CP violation (SM and non-SM) • CKM studies • Bs mixing • rare decays

  3. The upgraded D detector Muon Toroid Calorimeter Solenoid, Tracking System (CFT, SMT)

  4. Silicon Tracker Fiber Tracker 125 cm h=1.6 h=3 50cm 20cm Forward Preshower Solenoid Central Preshower DØ tracking system

  5. DØ - Muon detectors Central region: re-use Run I PDT new scintillators for triggering A-f Scint PDT’s Forward Trigger Scint new shielding for beampipe Shielding New forward system to replace Run I system: mini drift tubes scintillators for triggering Forward Tracker (MDTs) Bottom B/C Scint

  6. The DØ Trigger System • Towers, Tracks,missing ET • Some correl’s • Single Sub-Det’s • Not quite deadtimeless • Correlations • Calibrated Data • Physics Objects e,,jets,,missing ET • Simple Reco • Physics Algorithms L3 L1 L2 50 Hz 1 kHz 5 kHz Decision time ~50ms 2.3 MHz Decision time 100ms Decision time 4.2ms Current rates: L1/L2/L3 = 500/200/50 Hz

  7. Run II Luminosity most data used for commissioning data used in analyses ~ 5 pb-1

  8. b-quark production • LO/NLO/NNLO • QCD including • flavour excitation • gluon splitting

  9. Run I b-quark production cross-section Differential b-jet cross-section b production cross section as a function of minimum pt PRL 85, 5068 (2000) Mangano, Nason, Ridolfi Peterson frag.

  10. Is there a significant excess in B-meson production ? • Binnewies, Kniehl, Kramer, hep-ph/9802231: • correct treatment ofB fragmentation functions • similar approach from Cacciari, Nason, • hep-ph/0204025 • Frixione: NNLO might explain differences • ICHEP 2002 • Berger, hep-ph/0201229: SUSY

  11. Run II mu+jet cross section - preliminary 4.8 pb-1

  12. b-tagging at DØ offline • impact parameter • secondary vertexing trigger level • impact parameter at Level 3 • Silicon Track Trigger (STT) at Level 2

  13. Tagging b-jets: μ local muons only

  14. Tagging b-jets: di-muon sample data cc bb ptrel(μ2) (GeV) ptrel(μ2) (GeV) ptrel(μ2) (GeV) ptrel(μ1) (GeV) ptrel(μ1) (GeV) ptrel(μ1) (GeV)

  15. Tagging b-jets: impact parameter track jet axis jet axis dca track primary vtx positive IP negative IP

  16. Impact parameter tagging impact parameter significance = impact parameter/sqrt(error2(primary vtx)+error2(track)) sample high (b-enriched) generic di-jet sample background impact parameter significance impact parameter significance

  17. di-μ + jet candidate

  18. Run I J/ψ production cross section pt > 8 GeV 2.5  |η|  3.7 pt > 5 GeV

  19. Run II J/ψ and Ysignal σ(J/ψ) = 88 ± 3 MeV

  20. Run II J/ψ production cross section N(J/ψ) σ(J/ψ) = L εkine εreco εtrigger εaccept εtrack-match L Luminosity 4.8 pb-1 εtrigger: di-muon trigger. εreco:from scanning, muon system only εtrack-match: muons matched to central track εkine: only simulate muons which reach muon chamber εaccept: inactive material, etc.

  21. Run II J/ψ production cross section-preliminary 4.8 pb-1 of data ~30% systematic uncertainty region not measured in Run I

  22. Future measurements: J/ψ polarization CDF Run I θ = angle(J/ψlab,μJ/ψ) I(θ) = 3/2/(α+3) (1+ α cos2 θ) PRL 85, 2886(2000) α = (σT -2σL)/(σT +2σL) CEM: No polarization NRQCD: transverse at high pt

  23. J/ψ Polarization θ = angle(J/ψlab,μJ/ψ) pt(J/ψ) > 10 |η(J/ψ)| < 1.8 pt(μ) > 2 η(μ)| < 1.9

  24. Conclusions • Improved muon and new tracking systems • lower muon pt threshold, better resolution, • lower systematics • The detector is (mostly) working as planned. • The first analyses are well under way.

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