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Di-boson Physics at the TeVatron

Di-boson Physics at the TeVatron. Outline Introduction Measurement of W g cross section Measurement of Z g cross section Measurement of WW cross section WZ(ZZ) cross section limits. Andrew Alton University of Michigan. W. W. Z. W. W. Z. g. Z. g. Diboson Production.

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Di-boson Physics at the TeVatron

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  1. Di-boson Physics at the TeVatron Outline • Introduction • Measurement of Wg cross section • Measurement of Zg cross section • Measurement of WW cross section • WZ(ZZ) cross section limits Andrew Alton University of Michigan

  2. W W Z W W Z g Z g Diboson Production • SU(2)LxU(1)Y Electroweak sector • non-Abelian theory including boson couplings • WW, WWZ (Trilinear gauge boson vertices) • Events with two bosons are sensitive to trilinear gauge boson vertices. • The standard model (SM) has very specific (and small) predictions for the cross section of Di-boson events. • Extensions to the SM often enhance these cross sections. Especially for high boson pt. • Places limits on Anomalous Trilinear Couplings • These final states are backgrounds for other important physics (H->WW, tt->dilepton,etc) Andrew Alton, University of Michigan

  3. Electrons EM cluster in Cal Et >15 GeV (often higher 20,25) Track match Shower shape/likelihood CDF - |e| < 1.1, 1.2<|e| < 2.6(2.0) D0 - |e| < 1.1, 1.5<|e| < 2.5 Muons Muon chamber hits Central Track assoc. PT > 20 GeV(15 in Zg ) CDF - || < 1.0 D0 - || < 2.0(1.6) Photons EM cluster in Cal Et >7(8) GeV CDF(D0) Track veto and isolation Shower shape |g| < 1.1 Isolated Track Missing Et. Object Identification Andrew Alton, University of Michigan

  4. Wg Production • Wg also has an interesting feature • interference creates a zero amplitude in the charge signed rapidity difference between the l and g. Monte Carlo Andrew Alton, University of Michigan

  5. Wg Cross Section Andrew Alton, University of Michigan

  6. Photon Et Andrew Alton, University of Michigan

  7. Zg Cross Section Andrew Alton, University of Michigan

  8. Photon Et Andrew Alton, University of Michigan

  9. Two body vs Three Body Mass Andrew Alton, University of Michigan

  10. WW Cross Section s(pp->WW) = 14.3 +5.6–4.9(Stat) 1.6(sys)  0.9(lum) CDF (lep+trk) = 19.4  5.1(stat)  3.5(sys)  1.2(lum) CDF (dilepton) = 13.8 +4.3–3.8(Stat) 1.0(sys)  0.9(lum) D0 * CDF uses 13.3  0.8 while D0 assumes 13.0 Andrew Alton, University of Michigan

  11. WZ to tri-leptons • D0 looks for W/Z to 3 leptons(e and m). • Expects 0.39  0.02 background events • Expects 1.02  0.07 signal events (assuming 3.7 pb) • Find 1mmm candidate event. • Set upper limit on cross section of 15.1 pb Andrew Alton, University of Michigan

  12. Candidate Event Andrew Alton, University of Michigan

  13. WZ and ZZ Production • CDF looks for a WZ and ZZ candidates by requiring a Z(ee or mm) and • Met Significance (sensitive to Z->nn and WZ) • Or third lepton & MET • Or four leptons. • Expect 2.72+-0.33 of signal • And 2.29+-0.42 of background • Find 4 candidates (all 2 track) • Set a limit s(ZZ+ZW)<13.9 pb • Theory is s(ZZ+ZW)=5.2+-0.4 pb Andrew Alton, University of Michigan

  14. Conclusions • Both Tevatron experiments are doing well. • Collection of preliminary cross sections: • Expect limits on anomalous couplings • Analysis using hadron final states underway. • Expect final results and publications soon. Andrew Alton, University of Michigan

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