1. 19-24 May 2003K. Goulianos, CIPANP-20031 Konstantin Goulianos The Rockefeller University & The CDF Collaboration CIPANP-2003, New York City, 19-24 May 2003 Introduction Soft Diffraction Hard Diffraction Conclusion Aspects of Diffraction at the Tevatron Selected reviews: hep-ex/0011059, hep-ex/0011060, hep-ph/0205141, hep-ph/0203217

2. 19-24 May 2003K. Goulianos, CIPANP-20032 Introduction X Diffraction dissociation KG, Phys. Rep. 101 (1983) 171 coherence What is hadronic diffraction?

3. 19-24 May 2003K. Goulianos, CIPANP-20033 rapidity gaps are regions of rapidity devoid of particles Gaps are exponentially suppressed From Poisson statistics: ( r =particle density in rapidity space) large rapidity gaps are signatures for diffraction rapidity gaps are formed by multiplicity fluctuations rapidity gaps, like diamonds, ‘live for ever’  Non-diffractive interactions:  Diffractive interactions: Diffraction and Rapidity Gaps

4. 19-24 May 2003K. Goulianos, CIPANP-20034  Quark/gluon exchange across a rapidity gap: POMERON  No particles radiated in the gap: the exchange is COLOR-SINGLET with quantum numbers of vacuum  Rapidity gap formation: NON-PERTURBATIVE  Diffraction probes the large distance aspects of QCD: POMERON CONFINEMENT  PARTONIC STRUCTURE  FACTORIZATION ? The Pomeron

5. 19-24 May 2003K. Goulianos, CIPANP-20035  Elastic scattering  Total cross section  Diffraction PRD PRL PRL PRL 50 (1994) 5535 87 (2001)141802 to be sub’d submitted SOFT diffraction HARD diffraction Control sample W 78 (1997) 2698JJ 74 (1995) 855JJ 85 (2000) 4217 JJ 79 (1997) 2636JJ 80 (1998) 1156 b-quark 84 (2000) 232JJ 81 (1998) 5278 J/  87 (2001) 241802 JJ 84 (2000) 5043 JJ 88 (2002) 151802 with roman pots PRL reference PRD 50 (1994) 5518 PRD 50 (1994) 5550 Diffraction at CDF in Run I

6. 19-24 May 2003K. Goulianos, CIPANP-20036 Hard diffraction PLB 531(2002)52PRL 72(1994)2332Conference report W-conf. reportPRL 76(1996)734 PRB 440(1998)189 Diffraction at D0 in Run I

7. 19-24 May 2003K. Goulianos, CIPANP-20037 Factorization & Renormalization Soft diffraction Renormalize to unity KG, PLB 358(1995)379 Gap probability  COLOR FACTOR Pomeron trajectory parton model

8. 19-24 May 2003K. Goulianos, CIPANP-20038 Total cross section KG, PLB 358 (1995) 379 Differential cross section KG&JM, PRD 59 (114017) 1999 REGGE RENORM s-independent  Differential shape agrees with Regge  Normalization is suppressed by factor  Renormalize Pomeron flux factor to unity M 2 SCALING Soft Single Diffraction (CDF-I)

9. 19-24 May 2003K. Goulianos, CIPANP-20039  Double Pomeron Exchange  Measure  Plot #Events versus log(  )  SDD: single+double diffraction  Central gaps in SD events Central and Double Gaps (CDF-I) Double Diffraction Measure #Events versus 

10. 19-24 May 2003K. Goulianos, CIPANP-200310 Differential shapes agree with Regge predictions  One-gap cross sections require renormalization DDSDDDPE  Two-gap/one-gap ratios are Central and Double-gap Results (CDF)

11. 19-24 May 2003K. Goulianos, CIPANP-200311 5 independent variables Gap probability Sub-energy cross section (for regions with particles) Integral Renormalization removes the s-dependence SCALING color factor Two-gap Diffraction (hep-ph/0205141)

12. 19-24 May 2003K. Goulianos, CIPANP-200312 Hard diffraction (Run I) BBC 3.2<  <5.9 FCAL 2.4<  <4.2 BBC FCAL Tag rapidity gaps Tag antiproton Diffractive dijets

13. 19-24 May 2003K. Goulianos, CIPANP-200313  SINGLE DIFFRACTION  DOUBLE DIFFRACTION XCDFD0 W1.15 (0.55) JJ0.75 (0.10)0.65 (0.04) b0.62 (0.25) J/  1.45 (0.25) SD/ND gap fraction (%) at 1800 GeVDD/ND gap fraction at 1800 GeV All SD/ND fractions ~1% Gluon fraction Suppression by ~5 relative to HERA Just like ND except for the suppression due to gap formation Hard Diffraction Using Rapidity Gaps

14. 19-24 May 2003K. Goulianos, CIPANP-200314 ISSUES: 1) QCD factorization > is F SD universal? 2) Regge factorization > (not detected) Bjorken-x of antiproton Nucleon structure function Diffractive structure function ? momentum fraction of parton in IP METHOD of measuring F SD : measure ratio R( ,t) of SD/ND rates for given ,t set R( ,t)=F SD /F ND evaluate F SD = R * F ND Diffractic Dijets with Leading (CDF)

15. 19-24 May 2003K. Goulianos, CIPANP-200315 Test Regge factorization Test QCD factorization Regge factorization holdsSuppressed at the Tevatron relative to predictions based on HERA parton densities !!! Dijets in Single Diffraction (CDF-I)

16. 19-24 May 2003K. Goulianos, CIPANP-200316 (not detected) R(SD/ND) R(DPE/SD) Test of factorization equal? Factorization breaks down The second gap is un-suppressed!!! Dijets in Double Pomeron Exchange (CDF-I)

17. 19-24 May 2003K. Goulianos, CIPANP-200317 Run II Diffraction at the Tevatron CDF and D0 Forward Detectors MiniPlug calorimeters (3.5<  <5.5) Beam Shower Counters (5.5<  <7.5) Antiproton Roman Pot Spectrometer  Roman Pot Spectrometers on proton & antiproton sides

18. 19-24 May 2003K. Goulianos, CIPANP-200318 J5At least one cal tower with ET > 5 GeV RP inclusiveThree-fold coincidence in RP trigger counters RP+J5Single Diffractive dijet candidates RP+J5+BSC-GAP_pDouble Pomeron Exchange dijet candidates Triggers  Results presented are from ~26 pb -1 of data  The Roman Pot tracking system was not operational for these data samples  The  of the (anti)proton was determined from calorimeter information: (-)+ is for (anti)proton Run II Data Samples (CDF)

19. 19-24 May 2003K. Goulianos, CIPANP-200319 R=(SD/  ND ND+SD & SD+MB overlap events  ~ 1 SD events 0.03<  <0.1 Agreement with Run I No Q2 dependence Run II Dijets in Single Diffraction (CDF) Flat region

20. 19-24 May 2003K. Goulianos, CIPANP-200320 Exclusive dijets? Run II Dijets in DPE (CDF)

21. 19-24 May 2003K. Goulianos, CIPANP-200321 Inclusive/Exclusive DPE Dijet Predictions

22. 19-24 May 2003K. Goulianos, CIPANP-200322 Run II: Exclusive DPE Dijets ? No exclusive dijet bump observed Generous upper limit on exclusive dijets

23. 19-24 May 2003K. Goulianos, CIPANP-200323 Double Pomeron Exchange Dijet Events Rjj=0.81, Jet1(2)=33.4(31.5) GeVRjj=0.36, Jet1(2)=36.2(33.3) GeV

24. 19-24 May 2003K. Goulianos, CIPANP-200324 SUMMARY Soft and hard conclusions SOFT 1) Differential shapes agree with factorization based Regge predictions 2) Single-gap production rates are suppressed as the energy increases 3) Renormalizing the gap probability to unity yields correct rates 4) Two-gap to one-gap ratios are ~ equal to Same general features as in soft diffraction HARD COLOR FACTOR