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Physics with Muons: D Ø Highlights

No Shielding. D0 Shielding. D0 Interaction lengths. 0 10 20 l. Physics with Muons: D Ø Highlights. Exciting new results from analyses presented at Moriond 2004 on B Physics New Phenomena searches Electroweak & Top Studies Integrated Lum’y up to 250 pb -1

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Physics with Muons: D Ø Highlights

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  1. No Shielding D0 Shielding D0 Interaction lengths 0 10 20l Physics with Muons: DØHighlights • Exciting new results from analyses presented at Moriond 2004 on • B Physics • New Phenomena searches • Electroweak & Top Studies Integrated Lum’y up to 250 pb-1 • With emphasis on the strategy brought on because of the muon system. Tom Diehl (FNAL) For D0 Collaboration

  2. Acknowledgements Special thanks to S. Burdin, A. Nomerotski, J. Stark, G. Watts, M. Verzocchi, and R. Kehoe for discussions and for many of the slides.

  3. SMT SMT SMT Muon System and Tracker • New muon system with |h|<2 and good shielding • 4-layer Silicon and 16-layer Fiber Trackers in 2 T magnetic field

  4. Properties of a Good B Physics Detector* * From “B Physics @ the Tevatron: Run 2 and Beyond” • A high precision vertex detection • Tracking w/ excellent momentum resolution • Excellent particle ID capability • Robust trigger integrated into a high bandwidth DAQ No specific mention of importance of muons?

  5. Properties of a Good B Physics Detector* * From “B Physics @ the Tevatron: Run 2 and Beyond” • A high precision vertex detection • Tracking w/ excellent momentum resolution • Excellent particle ID capability • Robust trigger integrated into a high bandwidth DAQ The point is, muon trigger and ID is only one of several required elements. (BUT it turns out to be most advantageous to have powerful muon trigger and ID. Trigger on: J/y and/or a tagging lepton. No Lifetime cuts in trigger.)

  6. J/y -> mm: Run 1 vs. Run 2 • Run I: 407  62 J/y • 6.6 pb-1 out of 13 pb-1 • pT(m)>8 |eta(m)|<1 • ~35% from B’s • s(1/p)= 0.18/p2 + 0.003 • Run II: 1.2M J/y • 250 pb-1 • pT(m)>0.18 |eta(m)|<2ish • [s(pT)/pT]2 ~ 0.0152 + (0.0014pT)2

  7. Why so many J/psi in Run II? |h(m)|< 2.0 • pT(m) of J/psi in B-decays • Monte Carlo |h(m)|< 2.0 • 16% have 2m pT >1.5 GeV/c • 7% have 2 m pT > 1.5 & 1 m pT > 3.5 GeV/c • 0.1% have 2m pT > 6.0 GeV/c • It’s the trigger that gets them onto tape. • It’s the solenoid & tracking that provides the skinny peak. (GeV/c) Run 1 pT(m) pT(m) (GeV/c)

  8. Tracking Performance pT spectrum of soft pion candidate in D*D0 Tracks are reconstructed starting from pT = 180 MeV (Lower pT is better)! Muon h in J/psi events Data Lower trig threshold in magnet corner Coverage of Muon system is matched by L3/offline tracking “This greatly enhances our B-physics program.” - A.N.

  9. Tracking Performance Impact Parameter Resolution SMT dE/dx NOT yet used for PID P/K/p separation for some pT • (DCA)  16 m@PT = 10 GeV (DCA)  54 m@PT = 1 GeV • Resolution compares well with MC More tracking improvements under way

  10. X(3872)  J/ + - Last summer, Belle announced a new particle at  3872 MeV/c2, observed in B+ decays: B+  K+ X(3872), X(3872)  J/ + - Nature of X(3872) is not known • could be charmonium, meson molecule etc. Belle’s discovery has been confirmed by CDF and DØ. 300  61 events, a 4.4 bump M = 0.7680.004(stat)0.004(syst) GeV/c2 Compared properties of sample of X particles to sample of (2S): no differences seen in pT, d.l., isol, h … (2S) -> (1S)p+p- w/ br (31%) M[(2S)] - M[(1S)] = 589 MeV/c2

  11. Exclusive B Decays • Accumulated large exclusive samples of B+ and B0 Find in 250 pb-1: B+ J/yK+ 4306 events B0 J/yK* 1900 events B0 J/yKs 375 events Lb J/y L 52 events MLb=5615 9 MeV/c2 • Good S/B • Lifetime cuts applied lxy/(lxy)>4.5

  12. 250 pb-1 Bs Exclusive Decays Bs m nDs (f p) Bd m nD+ (f p) The world largest sample of exclusive Bs J/y f (K+K-) decays • Work in progress on • Lifetime measurements • Studies of Mixing & CP effects Some lifetime cuts applied + cc M(fp) GeV/c2 • Work in progress on Bs/Bd lifetime ratio and first results on Bs mixing • need to fully understand time resolution • if ms 15ps-1 expect a measurement with 500 pb-1

  13. B m nD0 X K+p - Semileptonic Bd sample • Collected by low pT single muon triggers • 109k B+m n D0 candidates • 25k B0m n D* candidates • D* yield 50% higher for looser selections • Plots below have (offline) lifetime cuts Sample compositions: “D0 sample”: 82% fromB+ “D* sample”: 86% fromB0 Estimates based on measured branching fractions and isospin relations.

  14. (B+)/(B0): Result one example : VPDL bin [0.10 - 0.15 cm] Use binned c2 fit of event ratios to determine (B+)/(B0) VPDL=LT/pT(mD0)*Mb Preliminary result: (B+)/(B0) = 1.093  0.021 (stat)  0.022 (syst) (among the most precise of this quantity)

  15. B0  B0/B0 Mixing: Milestone ! Tagging procedure • opposite side tight muon • muon pT > 2.5 GeV/c • cosDf(m, B)< 0.5 Fit procedure • Binnedc2fit Preliminary results: md=0.5060.055(stat)0.049(syst) ps-1 Tagging efficiency: 4.8  0.2 % Tagging purity: 73.0  2.1 % • Already one of the best measurements at hadron collider • Good prospects to improve accuracy • work in progress to decrease systematic uncertainty • use other tagging methods: jet charge, same side tagging, electron tagging • add more D0 decay channels

  16. Observation of B    D** X D** are orbitally excited D meson states • Start from B  D*X sample, add another + • Look at invariant mass of D*- + system • Observed merged D10(2420) and D2*0(2460) Two interfering Breit-Wigner D** states with mass/width as measured by Belle (no resolution effects included) Work in progress:extract separate amplitude for each state and relative phase of interference wrong-sign combinations Unique observation at hadron collider Preliminary result on product branching ratio Br(B  {D10,D2*0}   X)  Br({D10,D2*0}  D*+ -) = 0.280  0.021 (stat)  0.088 (syst) % measured by normalizing to known Br (B  D*+   X)

  17. Properties of a Good High pT Muon Detector Moderate h Coverage Accep’ for both muons • High pT > 10 GeV/c • e.g. Top Pairs • Most high-pT physics is centralish • Don’t need to cover past |h|=2 TTbar->mmnnbb |h|=2 Low Background • The Physics is cross-section limited • Require a robust high-pT unprescaled trigger. • Rejection against low pT muons, cosmics, meson in-flight decay.

  18. W & Z to Muons in Run 1 • 13 pb-1 (Run 1a) • 1665 W’s • 77 Z’s • Muons + jets or EM was much better off at trigger level.

  19. W->mn and Z->mm Cross Sections Cut at 16 ns • Z->mm in 117 pb-1. • 2 opposite-charged tracks w/ pT>15 GeV/c • At least one is isolated • Scintillator timing, DCA, acolinearity cuts to remove small backgrounds • In 150 pb-1 we have ~ 15,000 of these due to improvements in the trigger. In 250 pb-1… • Testing our understanding of the systematics (Update soon). # Events \ ns s*Br = 261.8 ± 5.0 (stat) ± 8.9 (sys) ± 26.2 (lum) pb (prior to reduction in dL) 117 pb-1 6126 events

  20. W->mn and Z->mm Cross Section • W->mn in 17.3 pb-1. • An isolated muon w/ pT>20 GeV/c in |h|<1.6 • Bkgd is Z, W->tn, QCD • Veto if additional muons. • F(bkgd.)=0.118 • 8305 Candidates after background subtraction • In 104 pb-1 we have ~73,000 W->mn. In 250 pb-1… s*Br = 3226 ± 128 (stat) ± 100 (sys) ± 322 (lum) pb R is high in these early results.

  21. Wg Cross Section: Small cross section in SM Sensitive to new Physics e or m and n and photon w/ (ET>8 GeV) & DR(lg>0.7) Signature s(ppWglng+X) 19.3 ± 6.7 ± 1.2(lumi) pb A First Step to Trilinear Gauge Couplings

  22. New Phenomena Searches • SUSY Search for Squarks and Gluinos in the Jets+MET Topology Search for mSUGRA SUSY in the Like-Sign Muon Channel Search for Chargino/Neutralino in ee(+l) Final State Search for Chargino/Neutralino in Trilepton Final State Search for GMSB SUSY in Di-photon Events with Large MET • Leptoquarks Search for the First Generation Leptoquark • Extra Dimensions Search for LED in Jets+MET Topology Search for Large and TeV-1 ED in Di-electron Channel LED in Di-electron and Di-photon Channels • Z’ Search for Heavy Z' Bosons in Di-electron Channel • Higgs H->WW->dileptons H++H--->m+m+m-m- Search Submitted to PRL (First D0 Run II Publication) SM is safe for another day

  23. Top Quark Precision Measurement in Run 2 Top Cross Sections Cross Check SM with MTop Single top Rare Decays Top Mass Constrain MHiggs + soft muon tags Run 1 World Average Top Mass Run 2 Cross Sections All jets, dilepton, l+jets

  24. Di-Lepton Top Cross Section Lore: “Small cross section. Relatively free of SM backgrounds.” SM Backgrounds Instrumental Fakes Estimated on data Fakes ALPGEN+Pythia Isolated Lepton Fakes Working on optimizing the selection criteria

  25. Lepton + Jets

  26. Leptons + jets Top Cross Section Summary

  27. Run 1 Top Mass Combination DØNew Run I Top Mass = 180.1 ± 5.3 GeV/c2 (see Juan Estrada April 25 W&C) “Old” Mt was 174.333 ± 5.141 GeV/c2. Role for muon is to trigger & ID (low background).

  28. Summary/Conclusions • Details on all recent results can be found athttp://www-d0.fnal.gov/Run2Physics/WWW/results.htm • B-physics at DØ is online* with world class results • X(3782) seen • Record semileptonic & exclusive B samples • B Mixing & a precise measurement of B+/B0 lifetime ratio • High pT physics • W, Z, & Wg Cross Section and big samples in the can • top cross section at 1960 GeV & Run 1 Mass The powerful muon detector and trigger is a key contributor.

  29. Back-up slides& Unused slide storage

  30. Winter Conference Dataset ~170 pb-1 for these analyses All Data Reprocessed by December 2003 with improved reconstruction Thanks to all for the data!

  31. MG OH CH ICD FH MH EM FPS EM IH Calorimeters Central Cal. South End Cap North End Cap Readout Cell Cu pad readout on 0.5 mm G10 with resistive coat epoxy LAr in gap 2.3 mm Drift time ~430 ns • 50k readout cells (< 0.1% bad) • Fine segmentation • 5000 pseudoprojective towers ( 0.1  0.1 ) • 4 EM layers, shower-max (EM3): 0.05  0.05 • 4/5 Hadronic ( FH + CH ) • L1/L2 fast Trigger readout 0.2  0.2 towers • Fully commissioned Ur absorber • Liquid Argon sampling • uniform response, rad. hard, fine spatial segmentation • LAr purity important • Uranium absorber (Cu/Steel CC/EC for coarse hadronic) • nearly compensating, dense  compact • Uniform, hermetic with full coverage • || < 4.2 (  2o), int ~ 7.2 (total) • Single particle energy resolution • e: /E = 15% / E  0.3% : /E = 45% / E  4%

  32. Triggers for B physics • Robust and quiet single- and di-muon triggers • Large coverage |h|<2 • Variety of triggers based on • L1 Muon & L1 CTT (Fiber Tracker) • L2 & L3 filters • Typical total rates at medium luminosity (40 1030 s-1cm-2) • Di-muons : 50 Hz / 15 Hz / 4 Hz @ L1/L2/L3 • Single muons : 120 Hz / 100 Hz / 50 Hz @ L1/L2/L3 • Rates before prescaling: typically single muon triggers are prescaled or/and used with raised pT threshold at L1 • Muon purity 90% - all physics! • Current total trigger bandwidth 1600 Hz / 800 Hz / 60 Hz @ L1/L2/L3 • B-physics semi-muonic yields are limited by L3 filters and L3 bandwidth

  33. Observation of B    D** X • D** are orbitally excited D meson states, see diagram • In heavy quark limit expect two sets of doublet states • Two broad (decay through S-wave) • Two narrow (decay through D-wave) • Narrow D** • D01(2420)-> D*+p- • D*02(2460)-> D*+p- • One of decay channels Figure from Belle, hep-ex/0307021 D10, D2*0 have been observed and studied in several experiments, most recently by BaBar and Belle in B- D**0 - We study D10, D2*0 produced in semileptonic B decays.

  34. End Back Up Slides

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