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

3. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos2 - p Interactions Diffractive: vacuum exchange Protons retain their quantum numbers Non-diffractive: color exchange Protons acquire color and break apart

4. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos3 Why Study Particle Diffraction?

5. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos4 Asymmetric Fireworks? Po’< Po

6. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos5 Non-perturbative QCD THEORY  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! experiment phenomenology

7. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos6 1960’sBNL: first observation of pp -> pX 1970’sFermilab fixed target, ISR, SPS  Regge theory & factorization Review: KG, Phys. Rep. 101 (1983) 169 1980’sUA8: diffractive dijets  hard diffraction 1990’sTev Run-I: Regge factorization breakdown Tev vs HERA: QCD factorization breakdown 21 st C Multigap diffraction: restoration of factorization Ideal for diffractive studies @ LHC Forty Years of Diffraction Twenty Years at the Tevatron

8. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos7 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 Results  Total cross section  tot ~ s   Elastic cross section d  /dt ~ exp[2  ’ ln s ]  shrinking forward peak  Single diffraction Breakdown of Regge factorization Additional Detectors Trackers up to |  | = 7

9. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos8 Run 1-0 results in perspective KG, PLB 358 (1995) 379

10. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos9 CDF Run 1 (1992-1995) Run-IC Run-IA,B Forward Detectors BBC 3.2<  <5.9 FCAL 2.4<  <4.2

11. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos10 Diffraction @ CDF in Run I 93(2004)141601

12. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos11 All ratios ~ 1%  ~ uniform suppression ~ FACTORIZATION Diffractive Fractions @ CDF 1.45 (0.25)J/  0.62 (0.25)b 0.75 (0.10)JJ 1.15 (0.55)W Fraction(%) Hd Fraction: SD/ND ratio at 1800 GeV

13. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos12 Tevatron vs HERA: Breakdown of QCD Factorization CDF H1

14. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos13 Multigap Diffraction (KG, hep-ph/0205141)  y

15. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos14 Elastic and Total Cross Sections QCD expectations y  Elastic cross section: forward scattering amplitude The exponential rise of  T (  y’) is due to the increase of wee partons with  y’ (see E. Levin, An Introduction to Pomerons,Preprint DESY 98-120) y  Total cross section: power law rise with energy  s

16. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos15 Gap probability MUST be normalized to unity! Single Diffraction 2 independent variables: t color factor gap probability sub-energy x-section

17. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos16 Single diffraction (re)normalized  No unitarity problem after eikonalization of the elastic amplitude Grows slower than ln s

18. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos17 Total Single Diffractive x-Section  Unitarity problem: Using factorization and std pomeron flux  SD exceeds  T at  Renormalization: Normalize the Pomeron flux to unity KG, PLB 358 (1995) 379

19. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos18 The Factors  and  Experimentally: KG&JM, PRD 59 (114017) 1999 g =0.20 q =0.04 R =-0.5 f g =gluon fraction f q =quark fraction Color factor: Pomeron intercept: CTEQ5L

20. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos19 Multigap Cross Sections Same suppression as for single gap! Gap probabilitySub-energy cross section (for regions with particles) 5 independent variables color factors

21. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos20 Central and Two-Gap CDF Results  One-gap cross sections are suppressed  Two-gap/one-gap ratios are Agreement with renormalized Regge predictions DDSDDDP E

22. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos21 Gap Survival Probability S = Results similar to predictions by: Gotsman-Levin-Maor Kaidalov-Khoze-Martin-Ryskin Soft color interactions

23. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos22 Diffractive DIS @ HERA e Q2Q2 ** p jet  reorganize Factorization holds: J. Collins e **  t p IP Pomeron exchangeColor reorganization Brodsky et al. rescattering?

24. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos23 Inclusive vs Diffractive DIS  P (0)-1 (  q  )/2 F 2 ~ x  qq  g =0.20  q =0. 04  R =-0.5 KG, “Diffraction: a New Approach,” J.Phys.G26:716-720,2000 e-Print Archive: hep-ph/0001092

25. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos24 Diffractive Dijets @ Tevatron p jet reorganize jet

26. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos25 F D JJ ( , Q 2 ) @ Tevatron

27. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos26 SD/ND Dijet Ratio vs x Bj @ CDF 0.035 <  < 0.095 Flat  dependence

28. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos27 Restoring Factorization @ Tevatron R(SD/ND) R(DPE/SD) DSF from two/one gap: factorization restored!

29. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos28 Gap Between Jets

30. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos29 Gap Between Jets Question Is the diffractive exchange BFKL-like or simply a color rearrangement?

31. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos30 valence quarks antiproton x=x= Low-x and Diffraction proton  g =0.20  q =0. 04  R =-0.5 g =0.5 q =0.3 SOFTHARD deep sea Derive diffractive from inclusive PDFs and color factors antiproton valence quarks p p

32. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos31 Run 2 CDF Diffractive Program  Single Diffraction   and Q 2 dependence of F jj D  Process dependence of F D (W, J/   Double Diffraction  Jet-Gap-Jet:  gap for fixed large  jet  Double Pomeron Exchange  F jj D on p-side vs  -pbar Also: Exclusive central production  Dijets,  c Other  Tev4LHC issues

33. EDS 2005, 15-20 May 2005Twenty Years of Diffraction at the Tevatron K. Goulianos32 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.