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Diffraction at the Tevatron

Diffraction at the Tevatron. XXXIII International Conference on High Energy Physics Moscow :: 28 July 2006. Andrew Hamilton Université de Genève for the CDF and D  Collaborations. Introduction. Diffraction: An exchange with the quantum numbers of the vacuum.

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Diffraction at the Tevatron

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  1. Diffraction at the Tevatron XXXIII International Conference on High Energy Physics Moscow :: 28 July 2006 Andrew Hamilton Université de Genève for the CDF and DCollaborations

  2. Introduction Diffraction: An exchange with the quantum numbers of the vacuum. • Goals of Diffractive Program at the Tevatron: • Understand the nature of diffractive exchange • Test the feasibility of diffraction as a tool to search for new physics at the LHC introduction Non-Diffractive Diffraction Color Exchange Vacuum QN Exchange ICHEP 2006, Moscow

  3. Outline • Diffraction at D: • physics plans • Inclusive Diffraction at CDF: • ratio of SD/ND dijets • Q2 dependence of t in SD dijets • Exclusive Production at CDF: • two mechanisms (QED and QCD) • searches for QED mediated e+e- • searches for QCD mediated  and dijets • Summary outline ICHEP 2006, Moscow

  4. Diffraction at D • Diffractive Analyses in Progress at D: • Double Pomeron Exchange (DPE) + Jets • Diffractive Structure Function • Diffractive Heavy Flavor • Exclusive Production • Diffractive Z • Diffractive W • Inclusive DPE D plans ICHEP 2006, Moscow

  5. Inclusive Diffraction at CDF • CDF inclusive • intro • Use high pT jets as a probe to measure Diffractive Structure Function,FjjD Pomeron  = Pparton / PPomeron  = Ppomeron / Pproton t = ( Pi - Pf )2 ICHEP 2006, Moscow

  6. Inclusive Diffraction Results • CDF inclusive • results • No Q2 dependence • (100 < Q2 < 10000 GeV2) • The Pomeron evolves like the proton • Slope of d/dt is independent of Q2 in SD dijets ICHEP 2006, Moscow

  7. p p  g dijet, , c, Higgs e+e-, +- g g  p p Exclusive Production at CDF • Exclusive Production: QED or QCD mediated • CDF exclusive • intro QED QCD • measure exclusive QCD dijet and  production at Tevatron to constrain predictions on exclusive Higgs at LHC • measure exclusive QED e+e- and +-production at Tevatron to test feasibility of Luminosity measurement at LHC ICHEP 2006, Moscow

  8. QED Mediated e+e- Production • Exclusive e+e- events are selected by: • reconstructing the e+e- • requiring that there is no other activity in ||<7.4 • protons are not tagged • CDF exclusive • e+e- Tower Threshold: 30 MeV 16 events similar are found. ICHEP 2006, Moscow

  9. QED Mediated e+e- Production • Background estimate: 2.1+0.7 • exp =1.6 +0.5 (stat) + 0.3 (sys) pb • LPAIR =1.711 + 0.008 pb • CDF exclusive • e+e- -0.3 - -0.3 - ICHEP 2006, Moscow

  10. 1+3 events are predicted from ExHuME MC -1 Monk & Pilkington. hep-ph/0502077 QCD Mediated  Production • Exclusive  events: • selected in the same way as e+e- (except tracking) • agreement of exclusive e+e- cross section gives confidence in analysis methodology • CDF exclusive •  Tower Threshold: 30 MeV 3 events are found. Background estimate is not yet complete ICHEP 2006, Moscow

  11. QCD Mediated Dijet Production • select DPE dijets: p + p  p + X (2jets+…) + gap • examine the dijet mass fraction Rjj • Strategy: • CDF exclusive • dijet Similar for DPEMC ICHEP 2006, Moscow

  12. QCD Mediated Dijet Production • Another Observable: • exclusive gg  qq is suppressed by JZ=0 rule • exploit this by looking at fraction of heavy flavor (b/c) jets in dijet data as a function of Rjj • CDF exclusive b/c jets suppressed at high Rjj the two observables agree • dijet ICHEP 2006, Moscow

  13. QCD Mediated Dijet Production • The data favors ExHuME MC • CDF exclusive • How does the cross section compare? • dijet • Ratio of exclusive to inclusive DPE cross sections is flat. ICHEP 2006, Moscow

  14. Summary • Diffraction at D: • many analyses in progress • Inclusive Diffraction at CDF: • Q2 dependence of Diffractive Structure Function • slope of SD dijet d/dt is independent of Q2 • Exclusive Production at CDF: • observed e+e- production via QED exchange • possible evidence for  production via QCD exchange • observed dijet production via QCD exchange • KMR / ExHuME predictions are consistent with data • see previous talk for impact KMR of predictions on the LHC summary ICHEP 2006, Moscow

  15. Backup Slides • Backup Slides ICHEP 2006, Moscow

  16. Tevatron Luminosity ICHEP 2006, Moscow

  17. Forward Detectors ICHEP 2006, Moscow

  18. ee Numbers ICHEP 2006, Moscow

  19. ee Numbers ICHEP 2006, Moscow

  20. ee Plots ICHEP 2006, Moscow

  21. Dijet Plots DATASETS: Exclusive / Inclusive fraction: 310 pb-1 Heavy Flavor fraction: 200 pb-1 ExHuME DPEMC ICHEP 2006, Moscow

  22. Dijet Plots ICHEP 2006, Moscow

  23. Dijet Plots B B A A ICHEP 2006, Moscow

  24. Dijet Cross Section ICHEP 2006, Moscow

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