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Twenty Years of Diffraction at the Tevatron

Twenty Years of Diffraction at the Tevatron. K. Goulianos The Rockefeller University EDS 2005 15-20 May 2005 Chateau de Blois, France. http://physics.rockefeller.edu/dino/my.html. - p Interactions. Diffractive: vacuum exchange. Non-diffractive: color exchange. Protons retain their

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Twenty Years of Diffraction at the Tevatron

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  1. Twenty Years of Diffractionat the Tevatron K. Goulianos The Rockefeller University EDS 2005 15-20 May 2005 Chateau de Blois, France http://physics.rockefeller.edu/dino/my.html

  2. -p Interactions Diffractive: vacuum exchange Non-diffractive: color exchange Protons retain their quantum numbers Protons acquire color and break apart Twenty Years of Diffraction at the Tevatron K. Goulianos

  3. Why StudyParticle Diffraction? Twenty Years of Diffraction at the Tevatron K. Goulianos

  4. Po’< Po Asymmetric Fireworks? Twenty Years of Diffraction at the Tevatron K. Goulianos

  5. Non-perturbative QCD • Important for understanding hadron structure and quark confinement • Need to develop new mathematical methods • Diffraction offers an arena on which to confront non-pQCD pure thinking! THEORY phenomenology experiment Twenty Years of Diffraction at the Tevatron K. Goulianos

  6. Forty Years of DiffractionTwenty Years at the Tevatron • 1960’s BNL: first observation of pp -> pX • 1970’s Fermilab fixed target, ISR, SPS •  Regge theory & factorization • Review: KG, Phys. Rep. 101 (1983) 169 • 1980’s UA8: diffractive dijets a hard diffraction • 1990’s Tev Run-I: Regge factorization breakdown • Tev vs HERA: QCD factorization breakdown • 21st C Multigap diffraction: restoration of factorization • Ideal for diffractive studies @ LHC Twenty Years of Diffraction at the Tevatron K. Goulianos

  7. CDF Run 1-0 (1988-89) Elastic, single diffractive, and total cross sections @ 546 and 1800 GeV Roman Pot Spectrometers • Roman Pot Detectors • Scintillation trigger counters • Wire chamber • Double-sided silicon strip detector Additional Detectors Trackers up to |h| = 7 • Results • Total cross section stot ~ se • Elastic cross section ds/dt ~ exp[2a’ lns]  shrinking forward peak • Single diffraction Breakdown of Regge factorization Twenty Years of Diffraction at the Tevatron K. Goulianos

  8. KG, PLB 358 (1995) 379 Run 1-0 results in perspective Twenty Years of Diffraction at the Tevatron K. Goulianos

  9. Run-IC Run-IA,B Forward Detectors BBC 3.2<h<5.9 FCAL 2.4<h<4.2 CDF Run 1 (1992-1995) Twenty Years of Diffraction at the Tevatron K. Goulianos

  10. Diffraction @ CDF in Run I 93(2004)141601 Twenty Years of Diffraction at the Tevatron K. Goulianos

  11. Hd Fraction(%) W 1.15 (0.55) JJ 0.75 (0.10) b 0.62 (0.25) J/y 1.45 (0.25) Diffractive Fractions @ CDF Fraction: SD/ND ratio at 1800 GeV All ratios ~ 1% ~ uniform suppression ~ FACTORIZATION Twenty Years of Diffraction at the Tevatron K. Goulianos

  12. Tevatron vs HERA:Breakdown of QCD Factorization H1 CDF Twenty Years of Diffraction at the Tevatron K. Goulianos

  13. Multigap Diffraction (KG, hep-ph/0205141) f y Twenty Years of Diffraction at the Tevatron K. Goulianos

  14. f y Total cross section: power law rise with energy ~1/as The exponential rise of sT(Dy’) is due to the increase of wee partons with Dy’ (see E. Levin, An Introduction to Pomerons,Preprint DESY 98-120) f Elastic cross section: forward scattering amplitude y Elastic and Total Cross Sections QCD expectations Twenty Years of Diffraction at the Tevatron K. Goulianos

  15. t 2 independent variables: color factor Single Diffraction sub-energy x-section gap probability Gap probability MUST be normalized to unity! Twenty Years of Diffraction at the Tevatron K. Goulianos

  16. Grows slower than lns  No unitarity problem after eikonalization of the elastic amplitude Single diffraction (re)normalized Twenty Years of Diffraction at the Tevatron K. Goulianos

  17. Total Single Diffractive x-Section • Unitarity problem: Using factorization and std pomeron flux sSD exceeds sT at • Renormalization: Normalize the Pomeron flux to unity KG, PLB 358 (1995) 379 Twenty Years of Diffraction at the Tevatron K. Goulianos

  18. Color factor: Pomeron intercept: lg=0.20 lq=0.04 lR=-0.5 The Factors k and e Experimentally: KG&JM, PRD 59 (114017) 1999 CTEQ5L fg=gluon fraction fq=quark fraction Twenty Years of Diffraction at the Tevatron K. Goulianos

  19. 5 independent variables color factors Gap probability Sub-energy cross section (for regions with particles) Multigap Cross Sections Same suppression as for single gap! Twenty Years of Diffraction at the Tevatron K. Goulianos

  20. Agreement with renormalized Regge predictions DD SDD DPE • One-gap cross sections are suppressed • Two-gap/one-gap ratios are Central and Two-Gap CDF Results Twenty Years of Diffraction at the Tevatron K. Goulianos

  21. S = Gap Survival Probability Results similar to predictions by: Gotsman-Levin-Maor Kaidalov-Khoze-Martin-Ryskin Soft color interactions Twenty Years of Diffraction at the Tevatron K. Goulianos

  22. jet p x x,t IP p g* e g* Q2 e reorganize Brodsky et al. rescattering? Diffractive DIS @ HERA Factorization holds: J. Collins Pomeron exchange Color reorganization Twenty Years of Diffraction at the Tevatron K. Goulianos

  23. aP(0)-1 eg=0.20 (eq+l)/2 eq=0. 04 eR=-0.5 eq Inclusive vs Diffractive DIS KG, “Diffraction: a New Approach,” J.Phys.G26:716-720,2000 e-Print Archive: hep-ph/0001092 F2 ~ x-l Twenty Years of Diffraction at the Tevatron K. Goulianos

  24. jet p jet reorganize Diffractive Dijets @ Tevatron Twenty Years of Diffraction at the Tevatron K. Goulianos

  25. FDJJ(x,b,Q2) @ Tevatron Twenty Years of Diffraction at the Tevatron K. Goulianos

  26. SD/ND Dijet Ratio vs xBj@ CDF 0.035 < x < 0.095 Flat x dependence Twenty Years of Diffraction at the Tevatron K. Goulianos

  27. R(SD/ND) R(DPE/SD) Restoring Factorization @ Tevatron DSF from two/one gap: factorization restored! Twenty Years of Diffraction at the Tevatron K. Goulianos

  28. Gap Between Jets Twenty Years of Diffraction at the Tevatron K. Goulianos

  29. Question Gap Between Jets Is the diffractive exchange BFKL-like or simply a color rearrangement? Twenty Years of Diffraction at the Tevatron K. Goulianos

  30. p p valence quarks antiproton antiproton SOFT HARD eg=0.20 lg=0.5 eq=0. 04 lq=0.3 eR=-0.5 Low-x and Diffraction deep sea valence quarks Derive diffractive from inclusive PDFs and color factors x=x proton Twenty Years of Diffraction at the Tevatron K. Goulianos

  31. Run 2 CDF Diffractive Program • Single Diffraction • x and Q2 dependence of FjjD • Process dependence of FD (W, J/y) • Double Diffraction • Jet-Gap-Jet: Dhgap for fixed large Dhjet • Double Pomeron Exchange • FjjD on p-side vs x-pbar Also: Exclusive central production • Dijets, cc Other • Tev4LHC issues Twenty Years of Diffraction at the Tevatron K. Goulianos

  32. Summary • Diffraction is a low-x QCD phenomenon subject to color constraints. • Multigap processes offer the opportunity to study diffraction without complications arising from rapidity gap survival issues. • Regularities observed in Run 1 at the Tevatron and in results obtained at HERA paint a picture of the Pomeron as a composite object constructed from the underlying inclusive pdf’s of the (anti)proton. This picture could be further clarified and advanced to a theory by studies at the LHC. Twenty Years of Diffraction at the Tevatron K. Goulianos

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