1 / 17

top

Higgs. tracks. top. WZ. Top Physics At DØ. Top Physics At DØ. Leptons. Jets. b. DØ. Freya Blekman NIKHEF / Universiteit van Amsterdam. Outline. Introduction Triggers Analyses: tt  all hadrons tt  electron + jets Conclusion, Prospects. D Ø Run 2 M top.

jack
Download Presentation

top

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Higgs tracks top WZ Top Physics At DØ Top Physics At DØ Leptons Jets b DØ Freya Blekman NIKHEF / Universiteit van Amsterdam

  2. Outline • Introduction • Triggers • Analyses: tt  all hadrons tt  electron + jets • Conclusion, Prospects Freya Blekman NIKHEF/ Universiteit van Amsterdam

  3. DØ Run 2 Mtop Physics motivation • X-sec: QCD HQ production • Mass: Mtop provides restriction on Mhiggs • Top physics • spin correlations • Vtb DØ Run 1 Mtop Freya Blekman NIKHEF/ Universiteit van Amsterdam

  4. Tevatron Top Physics • (s)=1.96 TeV • Top pair production (this talk) • Single top • t  W + b BR > 99% • tt analyses classified by W decay channels • σ(pptt)≈ 7 pb Freya Blekman NIKHEF/ Universiteit van Amsterdam

  5. Background reduction most important factor Lepton + jets: Background mainly QCD and W + jets Hadronic channel: Background mainly QCD All tt channels: 2 b-jets!  B-tagging of vital importance Event topology jet e+jets:4 jets + e + νe b-jet jet b-jet e jet  jet b-jet Hadronic: 6 jets jet b-jet jet Freya Blekman NIKHEF/ Universiteit van Amsterdam

  6. Triggers • Hadronic channel: focus on jet multiplicity, high total transverse energy (= HT) • Electron + jets channel: focus on electron identification + jet multiplicity Freya Blekman NIKHEF/ Universiteit van Amsterdam

  7. tt  e + jets (L. Phaf, I. Iashvili et al.) • Finding electrons: EM ID efficiency • High pT electrons: Count Z  e+e- with and without ID cuts ID cuts: isolation, EM fraction, pT > 20 GeV, shower shape. Freya Blekman NIKHEF/ Universiteit van Amsterdam

  8. φ η tt  e + jets candidate • passes Run I cuts • Isolated electron • 4 reconstructed jets above • 15 GeV • HT = 191 GeV • Aplanarity = 0.11 Freya Blekman NIKHEF/ Universiteit van Amsterdam

  9. Offline event selection • event-shape variables Freya Blekman NIKHEF/ Universiteit van Amsterdam

  10. φ η tt  e + jets candidate • passes Run I cuts • Isolated electron • 4 reconstructed jets above • 15 GeV • HT = 191 GeV • Aplanarity = 0.11 • Mtop (χ2 fit) = 165 GeV Freya Blekman NIKHEF/ Universiteit van Amsterdam

  11. tt  e + jets candidate Freya Blekman NIKHEF/ Universiteit van Amsterdam

  12. N jets > 5 Centrality > 0.6 HT > 225 GeV Aplanarity > 0.05 Jet multiplicity HT= total hadronic sum Centrality = HT/H Aplanarity tt  hadrons (F.Blekman,M.Vreeswijk,G.Massaro) After selection signal/bg ~1/30 (MC signal eff ~ 44 %) Data Lum: 2 pb-1 QCD MC Pythia, pT > 80 tt MC Pythia,hadronic tt Mtop = 174 GeV Freya Blekman NIKHEF/ Universiteit van Amsterdam

  13. ET scale: 59 GeV y E scale: 51 GeV x 40 +z ET G eV 2PI -3.7 -2 2 -1.2 phi 0.0 180 0 eta 1.2 0.0 3.7 tt  hadrons candidate event • 6 jets • Passes selection cuts • Secondary vertices tagged • Mtop (χ2 fit) = 168 GeV φ η Freya Blekman NIKHEF/ Universiteit van Amsterdam

  14. Secondary vertex probability DØ Run 2 Preliminary DØ Run 2 Data tt hadronic MC QCD MC Results Hadronic Channel • Efficiencies and Purities Results for preliminary study on 2 pb-1 Further study still to be done, but promising for larger dataset…. ANN output Freya Blekman NIKHEF/ Universiteit van Amsterdam

  15. Lepton + jet , di-lepton: For now: Use Analysis similar to Run 1 (based on event topology) Prospects Expect to have 50 pb-1 reconstructed data by February 2003 • All hadronic: • Make use of improved b-tagging Freya Blekman NIKHEF/ Universiteit van Amsterdam

  16. Conclusion • We see top events being produced at Tevatron • Improved b-tagging starting to make a difference • Potential measurement for the winter conferences • More interesting high pT physics to come: Stay Tuned… ! Freya Blekman NIKHEF/ Universiteit van Amsterdam

  17. Event Selection • event-shape variables ( hadronic channel) Sphericity Sphericity Aplanarity ttbar QCD data Thrust Oblateness Freya Blekman NIKHEF/ Universiteit van Amsterdam

More Related