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QCD Results at CDF

QCD Results at CDF. Inclusive Jet Cross Section Dijet Mass Jet Shapes Diffractive Dijets. Chicago . Booster. CDF. DØ. Tevatron. p sou rce. Main Injector (new). Tevatron Collider. C.M. energy 1.96 TeV 396 nsec bunch spacing. inst. lum. 2-3 x 10 31 cm -2 sec -1

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QCD Results at CDF

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  1. QCD Results at CDF • Inclusive Jet Cross Section • Dijet Mass • Jet Shapes • Diffractive Dijets Michele Gallinaro, "QCD Results at CDF" - XXXVIII Rencontres de Moriond, March 22-29, 2003

  2. Chicago  Booster CDF DØ Tevatron p source Main Injector (new) Tevatron Collider • C.M. energy 1.96 TeV • 396 nsec bunch spacing • inst. lum. 2-3 x 1031 cm-2sec-1 • delivered 4-7 pb-1 per week • goal: 12 pb-1 per week Michele Gallinaro, "QCD Results at CDF" - XXXVIII Rencontres de Moriond, March 22-29, 2003

  3. CDF II Detector • Tracking • Silicon • Central Outer Tracker • Time of Flight • Expanded Muon Coverage • Endplug Calorimeter • Forward Detectors • Trigger • Tracks @ L1 • Silicon Tracks @ L2 • DAQ (132 ns) Michele Gallinaro, "QCD Results at CDF" - XXXVIII Rencontres de Moriond, March 22-29, 2003

  4. QCD at the Tevatron • Tevatron Collider is a tool for precision tests of QCD • Compare to QCD predictions • Probe to small distance scales • Look for new physics • Higher center-of-mass energy than Run I • s = 1.96 TeV • Higher jet cross section Michele Gallinaro, "QCD Results at CDF" - XXXVIII Rencontres de Moriond, March 22-29, 2003

  5. Jet ET Spectrum Excess at high jet ET in Run I • Use cone algorithm • Different ET triggers • Use data when trigger is 99 % efficient Michele Gallinaro, "QCD Results at CDF" - XXXVIII Rencontres de Moriond, March 22-29, 2003

  6. Inclusive Jet Cross Section Continuous spectrum to higher Jet ET Systematic uncertainties Largest uncertainty (~ 5 %) Run II data extends Run I results by ~ 150 GeV Michele Gallinaro, "QCD Results at CDF" - XXXVIII Rencontres de Moriond, March 22-29, 2003

  7. Cross Section Fit Best fit to central jet cross section provided by CTEQ 6.1 Gluon distribution has large uncertainty in high x region Michele Gallinaro, "QCD Results at CDF" - XXXVIII Rencontres de Moriond, March 22-29, 2003

  8. Jet Cross Section vs h • QCD sub-processes at small angles • Central jets are more likely to signal new physics (hep-ph 0303013) Michele Gallinaro, "QCD Results at CDF" - XXXVIII Rencontres de Moriond, March 22-29, 2003

  9. Dijet Mass • Two highest ET jets • Search for resonances  Larger dijet mass events than in Run I Michele Gallinaro, "QCD Results at CDF" - XXXVIII Rencontres de Moriond, March 22-29, 2003

  10. High Dijet Mass Event Jet 1 ET = 666 GeV (corr) hdet = 0.31 Jet 2 ET = 633 GeV (corr) hdet = - 0.30 Run 152507 event 1222318 Dijet Mass = 1364 GeV (corr) CDF Run 2 Preliminary Michele Gallinaro, "QCD Results at CDF" - XXXVIII Rencontres de Moriond, March 22-29, 2003

  11. Dijet Mass Ratio: Run II/Run I Higher jet cross section than Run I  ratio agrees with theory to ~ 10 % in rate (~ 2 % in energy scale) Michele Gallinaro, "QCD Results at CDF" - XXXVIII Rencontres de Moriond, March 22-29, 2003

  12. Limits on New Particles • Search for new particles decaying to dijets. • Fit data to background • plus a narrow resonance • Calculate cross section • Find 95 % CL upper limit • Compare with theory  set upper limits on cross section Michele Gallinaro, "QCD Results at CDF" - XXXVIII Rencontres de Moriond, March 22-29, 2003

  13. Jet Shapes • Jets narrow at high ET • Herwig/Pythia agree well with data Michele Gallinaro, "QCD Results at CDF" - XXXVIII Rencontres de Moriond, March 22-29, 2003

  14. Forward Physics • Hard Single Diffraction • Double Pomeron Exchange Michele Gallinaro, "QCD Results at CDF" - XXXVIII Rencontres de Moriond, March 22-29, 2003

  15. Diffractive Dijets • Compare diffractive events to ND • Measure diffractive structure function • from RSD/NDvsx Bj overlap events Measure x ( p momentum loss fraction) from calorimeter information Michele Gallinaro, "QCD Results at CDF" - XXXVIII Rencontres de Moriond, March 22-29, 2003

  16. Ratio of SD/ND Events Ratio is independent of x interval Ratio is independent of Q2 Michele Gallinaro, "QCD Results at CDF" - XXXVIII Rencontres de Moriond, March 22-29, 2003

  17. Proton-Side Multiplicity (0,0) bin Michele Gallinaro, "QCD Results at CDF" - XXXVIII Rencontres de Moriond, March 22-29, 2003

  18. DPE Enhanced Sample • Use dedicated DPE trigger (RP+J5+GapE) • (0,0) bin  ~ 16,000 events (in Run I: ~ 100 evts) Michele Gallinaro, "QCD Results at CDF" - XXXVIII Rencontres de Moriond, March 22-29, 2003

  19. DPE: Kinematics Michele Gallinaro, "QCD Results at CDF" - XXXVIII Rencontres de Moriond, March 22-29, 2003

  20. Summary • Inclusive jet cross section extends beyond 550 GeV • Dijet mass up event up to 1364 GeV • First exclusion of new particle with mass > 1 TeV • Preliminary diffractive results show no Q2 dependence in SD/ND Run II analyses are well underway ! Michele Gallinaro, "QCD Results at CDF" - XXXVIII Rencontres de Moriond, March 22-29, 2003

  21. Backup Slides …TO FOLLOW… Michele Gallinaro, "QCD Results at CDF" - XXXVIII Rencontres de Moriond, March 22-29, 2003

  22. New Plug Calorimeter Scintillator + lead/steel (replaces gas detector) Full coverage up to || = 3.5 more precise measurement of forward jets Michele Gallinaro, "QCD Results at CDF" - XXXVIII Rencontres de Moriond, March 22-29, 2003

  23. New MiniPlug Calorimeter • Liquid Scintillator + lead • towerless geometry • Full coverage: 3.5< || < 5.1 Measure very forward jet energies Michele Gallinaro, "QCD Results at CDF" - XXXVIII Rencontres de Moriond, March 22-29, 2003

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