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Soft and hard diffraction Run II diffractive program Exclusive production

Diffractive results at the Tevatron. Michele Gallinaro – The Rockefeller University ICHEP, Beijing Aug. 16, 2004. Soft and hard diffraction Run II diffractive program Exclusive production. Diffraction in Run I. Large rapidity gaps are signatures for diffraction. Soft diffraction.

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Soft and hard diffraction Run II diffractive program Exclusive production

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  1. Diffractive results at the Tevatron Michele Gallinaro – The Rockefeller University ICHEP, Beijing Aug. 16, 2004 • Soft and hard diffraction • Run II diffractive program • Exclusive production

  2. Diffraction in Run I • Large rapidity gaps are signatures for diffraction Soft diffraction Hard diffraction Methods: large rapidity gaps or leading anti-proton tag Michele Gallinaro - ICHEP - Beijing, China - Aug. 16-22, 2004

  3. Rapidity gaps Rapidity gaps seen as zero multiplicity in both forward calorimeter and beam-beam counters Michele Gallinaro - ICHEP - Beijing, China - Aug. 16-22, 2004

  4. Diffractive rates DD/ND fractions PRL Measure SD/ND fractions at 1800 GeV 74 (1995) 855 80 (1998) 1156 81 (1998) 5278 72 (1994) 2332 76 (1996) 734 PLB 440 (1998) 189 PRL 84 (1997) 2698 PLB 574 (2003) 169 84 (1997) 2636 84 (2000) 232 87 (2001) 241802-1 • All SD/ND fractions ~ 1% • Different sensitivities to quark/gluon • gluon fraction fg=0.54 (0.15) extend range in Run II Michele Gallinaro - ICHEP - Beijing, China - Aug. 16-22, 2004

  5. Multiple gaps Determine gap survival probability experimentally in soft diffraction Gap rates suppressed by: jet radiation and non-pQCD Measure the rate of additional gaps in soft diffractive events Michele Gallinaro - ICHEP - Beijing, China - Aug. 16-22, 2004

  6. Gap survival • survival probability S(0.63 TeV)=0.29 S(1.80 TeV) =0.23 PRL 87 (2001) 141802-1 PRL 91 (2003) 011802-1 one-gap cross sections suppressed two-gap to one-gap ratios not suppressed Michele Gallinaro - ICHEP - Beijing, China - Aug. 16-22, 2004

  7. Diffractive dijets x: fraction of anti-proton momentum loss b: fraction of pomeron momentum carried by parton parton xBj  b.x Measure SD/ND ratio of dijet rates (LO QCD) PRL 84 (2000) 5043 • no significant x dependence Michele Gallinaro - ICHEP - Beijing, China - Aug. 16-22, 2004

  8. Diffractive structure function • CDF Run I result suppressed • by factor of ~10 relative to HERA • breakdown of QCD factorization (renormalization removes s-dependence) • K. Goulianos, PLB 358 (1995) 379 H1 CDF Michele Gallinaro - ICHEP - Beijing, China - Aug. 16-22, 2004

  9. Run II diffractive program Diffractive structure function • Q2 and x dependence • process dependence Exclusive production in DPE • dijet, heavy flavor, low-mass Jet-Gap-Jet w/large gaps Michele Gallinaro - ICHEP - Beijing, China - Aug. 16-22, 2004

  10. Diffractive dijets x : momentum loss fraction of pbar S(alltowers)ET e-h x= s Approx. flat atx<0.1 SD region const overlap events Michele Gallinaro - ICHEP - Beijing, China - Aug. 16-22, 2004

  11. Kinematic Properties compare ND and SD Michele Gallinaro - ICHEP - Beijing, China - Aug. 16-22, 2004

  12. SD/ND ratio in Run II • ratio of SD/ND dijet event rates compared to Run I data • slope and normalization agree with Run I result • no x dependence observed 0.03<x<0.1 • confirms Run I results x10 x0.1 • no appreciable Q2 dependence observed within 100 < Q2 < 1,600 GeV2 • pomeron evolves similarly to proton Michele Gallinaro - ICHEP - Beijing, China - Aug. 16-22, 2004

  13. DPE Dijet Production from SD data: DPE SD SD: proton side SD: anti-proton side Michele Gallinaro - ICHEP - Beijing, China - Aug. 16-22, 2004

  14. DPE dijets R(DPE/SD) vs R(SD/ND) ? 1-gap/0-gap 2-gap/1-gap ~5 factorization is restored R(DPE/SD)  5 × R(SD/ND) • additional gap is not suppressed Michele Gallinaro - ICHEP - Beijing, China - Aug. 16-22, 2004

  15. Exclusive production in DPE exclusive inclusive Khoze, Martin, Ryskin Eur. Phys. J. C23, 311 (2002) C25, 391 (2002) C26, 229 (2002) C. Royon, hep-ph/0308283 gap gap gap gap next talk! Attractive Higgs discovery channel at the LHC • Standard Model light Higgs: • “exclusive” channel  clean signal • MH=Mmiss= (s x1 x2)1/2 • sH(LHC)~3 fb, signal/background~3 (if DMmiss=1 GeV) Michele Gallinaro - ICHEP - Beijing, China - Aug. 16-22, 2004

  16. Exclusive production Measurement of exclusive processes can be used to calibrate Higgs predictions • Exclusive dijets: gg→ gg • exclusive gg → qq is suppressed • Exclusive cc: • small cross section, clean signal Michele Gallinaro - ICHEP - Beijing, China - Aug. 16-22, 2004

  17. Exclusive Dijets in Run I (not detected) PRL 85 (2000) 4215 Expected shape of signal events • antiproton tag: 0.035<x<0.095 • 2 jets, ET>7 GeV • proton-side gap (2.4<h<5.9)  observed 132 events Mjj Rjj= sjj (excl.) < 3.7 nb (95% CL) Mass fraction: Mx theory expectns ~1 nb (Run I kinematics) Michele Gallinaro - ICHEP - Beijing, China - Aug. 16-22, 2004

  18. DPE Enhanced Sample • Use Run II dedicated DPE trigger (RP+J5+BSC_Gap_P) Data presented from 26 pb-1: Michele Gallinaro - ICHEP - Beijing, China - Aug. 16-22, 2004

  19. Dijet Mass Fraction use dedicated DPE trigger (RP+J5+BSC_Gap_P) exclusive region rate falls smoothly as Rjj→ 1 no excess at large Rjj independent of rapidity gap size Khoze, Martin, Ryskin - Eur. Phys. J. C23, 311, 2002 ~ 60 pb (factor of 2 uncertainty) Michele Gallinaro - ICHEP - Beijing, China - Aug. 16-22, 2004

  20. Exclusive Dijet Events ? Rjj=0.81 Rjj=0.36 Michele Gallinaro - ICHEP - Beijing, China - Aug. 16-22, 2004

  21. Exclusive low-mass states pp pcp J/y g  mmg (gis soft) c (same quantum numbers as Higgs boson) Event selection: • start fromJ/y sample • exclusive events • invariant mass(mm+EM tower) Background: • cosmics • calorimeter noise Michele Gallinaro - ICHEP - Beijing, China - Aug. 16-22, 2004

  22. Event Selection Data sample of 93 pb-1 : • mass resolution is poor • bkg from multiplicity fluctuations (under threshold) • difficult to estimate noise contribution cross section upper limit for exclusive production sexcl (J/y+g) = 49 ± 18(stat) ± 39(syst) pb ~70 pb Khoze, Martin, Ryskin, Stirling , Eur. Phys. J. C 35, 211 (2004) Michele Gallinaro - ICHEP - Beijing, China - Aug. 16-22, 2004

  23. Summary • forward detectors working well • dedicated diffractive triggers • re-established Run I measurements • no significant Q2 dependence in SD/ND ratio • no exclusive dijet/low-mass production Michele Gallinaro - ICHEP - Beijing, China - Aug. 16-22, 2004

  24. If you want to know more… for a summary: K. Goulianos hep-ph/0407035 Michele Gallinaro - ICHEP - Beijing, China - Aug. 16-22, 2004

  25. Soft diffraction unitarity problem • sND exceeds sT at ~2 TeV ~10 Renormalization (normalize flux to 1) • 1 • measurement is suppressed by a factor of ~10 to Regge theory and agrees with renormalization model K. Goulianos, PLB 358 (1995) 379 PRD 50 (1994) 5518, 5535, 5550 Michele Gallinaro - ICHEP - Beijing, China - Aug. 16-22, 2004

  26. Heavy flavor quark jets Khoze, Martin, Ryskin Eur. Phys. J. C23, 311 (2002) exclusive dijets: gg→gg only • look for excess of events at large Rjj Michele Gallinaro - ICHEP - Beijing, China - Aug. 16-22, 2004

  27. DPE: kinematics Compare ND and SD and DPE Michele Gallinaro - ICHEP - Beijing, China - Aug. 16-22, 2004

  28. x: RP vs calorimeter overlap events x from RP signal region xcal distribution for slice of xRP Michele Gallinaro - ICHEP - Beijing, China - Aug. 16-22, 2004

  29. Predictions for LHC RLHC(JGJ/JJ) = (1.13 ± 0.16)/(0.23 ± 0.07) = (4.9 ± 1.6) % Michele Gallinaro - ICHEP - Beijing, China - Aug. 16-22, 2004

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