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Exploring DiBoson Production at the Tevatron: Results and Insights

Delve into the world of DiBoson production at the Tevatron with detailed results and valuable analyses. This study sheds light on the heavy boson interactions and the implications for physics beyond the Standard Model.

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Exploring DiBoson Production at the Tevatron: Results and Insights

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  1. Tevatron W/Z/ Results Part IIAttack of the DiBosons 15th Topical Conference on Hadron Collider Physics Michael Kirby for the CDF and D0 Collaborations Michael Kirby, Duke University

  2. Why study DiBoson production? • Heavy Boson + photon, Two Heavy Bosons • Natural extension of well understood and measured W and Z production • Precise predictions available from many NLO calculations • Small cross sections provide challenge • Sensitive to non-Standard Model physics, internal structure of W and Z • Places limits on Anomalous Trilinear Couplings • Good confirmation of SU(2)LxU(1)Y structure of Electroweak sector Michael Kirby, Duke University

  3. DiBoson Production at the Tevatron Michael Kirby, Duke University

  4. The Tevatron at Fermilab • Tevatron proton anti-proton collider at Fermilab • EBeam = 980 GeV • 36x36 bunches with 396ns spacing • Increased instantaneous Luminosity • Typical:4 - 5 x 1031 cm–2 s-1 • Record: ~7.83 x 1031 cm–2 s-1 • Tevatron has delivered in total~500 pb-1 • Long term, by the end of FY09 • Base goal: 4.4 fb-1 Design: 8.5 fb-1 Michael Kirby, Duke University

  5. Oct Jan Apr Jul Oct Jan Apr Jul Oct Jan 2002 2003 2004 200 pb-1 64 pb-1 CDF Run I Delivered To Tape Store Number Detector Integrated Luminosity Michael Kirby, Duke University

  6. The D0 Run II Detector Michael Kirby, Duke University

  7. The CDF Run II Detector ||= 1. ||=2. Michael Kirby, Duke University

  8. W Production • Includes the Triple Gauge Coupling • Anomalous terms (, ) • SM (=0, =0) • Interference between ISR and TGC produces Radiation Amplitude Zero • only in SU(2)xU(1) group • After Detector Simulation LO MC NEVENTS Q(-l) Michael Kirby, Duke University

  9. SM SM ET(g) GeV DR(l,g) Anomalous Couplings In the ET=0 limit, couplings equated with classical magnetic dipole and electric quadrupole Michael Kirby, Duke University

  10. W Event Selection •  Selection • Central Track assoc.  hits • PT > 20 GeV • CDF - || < 1.0 • D0 - || < 2.0 • Electron Selection • EM Cluster > 25 GeV • Matched Track • Shower Shape Discrimination • CDF - |e| < 1.1, 1.2<|e| < 2.6 • D0 - |e| < 1.1, 1.6<|e| < 2.5 • Missing Tranverse Energy • > 20 GeV for  candidates • > 25 GeV for e candidates pT Photon Muon ET ET Neutrino ET Photon Electron ET ET Neutrino Michael Kirby, Duke University

  11. W Event Selection Cont CDF Et ()>7 GeV DØ Et ()>8 GeV R(,l)>0.7 |  |<1.1 Cal & trk-iso •  Selection • Central Calorimeter • Shower profile discrimination • Calor. and Track Isolation • ET > 7 GeV (CDF) • ET > 8 GeV (D0) • -lepton separation • R(l,)>0.7  0  Shower Maximum Detector Pre-shower Detector • Background dominantly from W + jets • leading 0 fakes photon in jets • Additional Bckgs - Z, W , misreconstruction Michael Kirby, Duke University

  12. W Results Measured (W)BR(Wl)= 19.9 2.7 (stat+sys) 1.1 (lumi) pb Measured (W)BR(Wl)= 19.3 6.7 (stat +sys) 1.2 (lumi) pb NLO Theory = 19.3 1.3pb NLO Theory = 16.4 0.4pb Michael Kirby, Duke University

  13. ET Results CDF Run 2 Preliminary 202/pb D0 Run 2 Preliminary 162/pb Michael Kirby, Duke University

  14. R(l,) Results D0 Run 2 Preliminary 162/pb Michael Kirby, Duke University

  15. W: l-ET Transverse Mass D0 Run 2 Preliminary 162/pb Michael Kirby, Duke University

  16. CDF Run 2 Preliminary 202/pb Cluster Transverse Mass Greater sensitivity to Anomalous Couplings and RAZ in high CTM region Michael Kirby, Duke University

  17. Z Production • No ZZ Triple Gauge Coupling in Standard Model at tree level • no Radiation Amplitude Zero • Anomalous terms(hi0, hZi0) • SM (hi0=0, hZi0=0) • Excellent cross check for W production • Anomalous terms can be related to the dipole and quadrupole moments Z Z Z Z l Michael Kirby, Duke University

  18. Z Event Selection •  Selection • Central Track • PT > 20 GeV • opposite charge • CDF - || < 1.0 • Electron Selection • EM Cluster > 25 GeV • CDF - |e| < 2.6 • Invariant Mass > 40 GeV • Photon selection • ET > 7 GeV • R(l,)>0.7 pT Photon Muon ET pT Muon ET Photon Electron ET Electron • Background from Z + jets ET Michael Kirby, Duke University

  19. Z Results Backgrounds Measured (Z)BR(Zll) = 4.5 0.5 (stat + sys) 0.3 (lumi) pb Note: (W)/(Z) ≈3 while (W)/(Z) ≈10 NLO Theory = 4.5 0.3pb (ET > 7 GeV, R(l,)>0.7) Michael Kirby, Duke University

  20. Z Results CDF Run 2 Preliminary 202/pb CDF Run 2 Preliminary 202/pb CDF Run 2 Preliminary 202/pb CDF Run 2 Preliminary 202/pb Michael Kirby, Duke University

  21. Z Results CDF Run 2 Preliminary 202/pb CDF Run 2 Preliminary 202/pb Michael Kirby, Duke University

  22. WW, WZ, and ZZ Production • Complementary probe of Triple Gauge Coupling • higher Boson and Lepton PT indicates Anom. Coup. • Small cross sections make for challenging measurement • Study using leptonic decays of the W and Z • Important foundation for Higgs searches Michael Kirby, Duke University

  23. CDF: WW (Two approaches) Two complementary approaches • Dileptons: l+,l-: identified e, • Reject 76<Mll<106 & ETsig <3.0 • ET>25 • No High Et jets • Opposite sign & Isolation • DY, Z •  WZ/ZZ, Z •  top dilepton •  Fakes • (Identified e,)+Iso track • Reject ETsig <5.5 in all Mll • ET>25 • Njets<=1 • Opposite sign & Isolation Missing ET Signifigance (GeV) High S/B Increased acceptance Michael Kirby, Duke University

  24. CDF: WW cross section NLO (Campbell & Ellis, 1999) WW=12.50.8 pb e, l+track Michael Kirby, Duke University

  25. CDF: WW Beyond SM ggHWW 140<MH<180GeV/c2 Anomalous TGC WWZ/WW Jet: >15 GeV Cone 0.4 Michael Kirby, Duke University

  26. WWee or ZZee ? Michael Kirby, Duke University

  27. ZW, ZZ study in Run II Select Zll • Event selections • Four lepton events • Signal: ZZ • Background: Z/W+jets, multijet • Three lepton events • Signal: ZZ, ZW • Background: Z/W+jets, multijet • Two lepton events • Signal: ZZ, ZW • Background: WW, Drell Yan, Top, W+jets Michael Kirby, Duke University

  28. ZW, ZZ study in Run II • Cross section upper limit consistent with SM prediction of 5.2 ± 0.4 pb 95% Conf Limit Michael Kirby, Duke University

  29. The Next Steps • Tevatron has excellent DiBoson production studies ongoing. • Will measure limits on Anomalous Triple Gauge Couplings • W, Z, WW, ZW, and ZZ • Establish baseline for other DiBoson production • Already have WW searches for Higgs production and improving upon understanding of HW production (see Michael Gold’s talk on Thursday) • Non-dilepton analyses are underway Michael Kirby, Duke University

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