2. K. Goulianos The Rockefeller University Results from CDF on Diffraction  presented on behalf of the CDF collaboration  Workshop on Low x Physics Lisbon, Portugal, 28 June – 1 July, 2006

3. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos2 Contents  Introduction & Run I results  Run II results Exclusive Production Diffractive structure function

4. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos3 p-p Interactions Diffractive: Colorless exchange with vacuum quantum numbers Non-diffractive: Color-exchange Incident hadrons retain their quantum numbers remaining colorless pseudo- DECONFINEMENT Incident hadrons acquire color and break apart CONFINEMENT POMERONPOMERON Goal: understand the QCD nature of the diffractive exchange rapidity gap

5. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos4 Rapidity Gaps p p X p pp Particle productionRapidity gap   -ln  ln M X 2 ln s X Momentum loss fraction

6. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos5 Diffraction @ CDF   Elastic scatteringTotal cross section SD DDDPESDD=SD+DD  T =Im f el (t=0) OPTICAL THEOREM   GAP

7. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos6 Gaps in the sky!

8. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos7 Run 1-0 (1988-89) Elastic, single diffractive, and total cross sections @ 546 and 1800 GeV Roman Pot Detectors  Scintillation trigger counters  Wire chamber  Double-sided silicon strip detector  Total cross section  tot ~ s   Elastic cross section d  /dt ~ exp[2  ’ ln s ]  shrinking forward peak  Single diffraction Breakdown of Regge factorization Roman Pots with Trackers up to |  | = 7 Roman Pot Spectrometers CDF-I

9. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos8  Regge theory  SD exceeds  T at  Renormalization Pomeron flux integral (re)normalized to unity Renormalization KG, PLB 358 (1995) 379 Pomeron flux Factorization 

10. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos9 A Scaling Law in Diffraction KG&JM, PRD 59 (1999) 114017 Factorization breaks down so as to ensure M 2 -scaling! renormalization 1  Independent of S over 6 orders of magnitude in M 2 !

11. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos10 The QCD Connection y  The exponential rise of  T (  y’) is due to the increase of wee partons with  y’ (E. Levin, An Introduction to Pomerons,Preprint DESY 98-120) y  Total cross section: power law increase versus s Elastic cross section: forward scattering amplitude  s

12. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos11 2 independent variables: Gap probability Renormalization removes the s-dependence SCALING Single Diffraction in QCD t color factor (KG, hep-ph/0205141)

13. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos12 Multi-gap Renormalization Same suppression as for single gap! 5 independent variables Gap probabilitySub-energy cross section (for regions with particles) color factors (KG, hep-ph/0205141)

14. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos13 CDF-IA, IB Forward Detectors BBC 3.2<  <5.9 FCAL 2.4<  <4.2 beam

15. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos14  Double Diffraction Dissociation  One central gap  Double Pomeron Exchange  Two forward gaps  SDD: Single+Double Diffraction  One forward + one central gap Central and Double Gaps

16. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos15  One-gap cross sections are suppressed  Two-gap/one-gap ratios are Central & Double-Gap CDF Results Differential shapes agree with Regge predictions DDSDDDPE

17. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos16 CDF-IC Forward Detectors BBC 3.2<  <5.9 FCAL 2.4<  <4.2 beam

18. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos17 HARD DIFFRACTION  Diffractive fractions  Diffractive structure function  factorization breakdown  Restoring factorization  Hard diffraction in QCD  dN/d  JJ, W, b, J/ 

19. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos18 All ratios ~ 1%  ~ uniform suppression ~ FACTORIZATION ! Diffractive Fractions 1.45 (0.25)J/  0.62 (0.25)b 0.75 (0.10)JJ 1.15 (0.55)W Fraction(%) Fraction: SD/ND ratio at 1800 GeV

20. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos19 The diffractive structure function at the Tevatron is suppressed by a factor of ~10 relative to expectation from pdf’s measured by H1 at HERA Similar suppression factor as in soft diffraction relative to Regge expectations! Diffractive Structure Function: Breakdown of QCD Factorization CDF H1  = momentum fraction of parton in Pomeron Using preliminary pdf’s from

21. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos20 Restoring QCD Factorization R(SD/ND) R(DPE/SD) DSF from two/one gap: factorization restored! The diffractive structure function measured on the proton side in events with a leading antiproton is NOT suppressed relative to predictions based on DDIS

22. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos21 CDF-II ROMAN POT DETECTORS BEAM SHOWER COUNTERS: Used to reject ND events MINIPLUG CALORIMETER

23. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos22 The MiniPlugs @ CDF

24. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos23 MiniPlug Calorimeter About 1500 wavelength shifting fibers of 1 mm dia. are ‘strung’ through holes drilled in 36x¼” lead plates sandwiched between reflective Al sheets and guided into bunches to be viewed individually by multi-channel photomultipliers.

25. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos24 Run II Results  Diffractive structure function  Q 2 - dependence  t - dependence  Exclusive production  dijet  diphoton

26. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos25 Diffractive Dijet Signal Overlap events: mainly ND dijets plus SD low  RPS trigger - Bulk of data taken with RPS trigger but no working RPS tracking - Extract  from calorimetric information - Calibrate calorimetric  using limited sample of RPS tracking data - Subtract overlap background using a rescaled dijet event sample - Verify diffractive  range by comparing  RPS with  CAL

27. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos26  CAL Calibration overlap events signal region  cal distribution for slice of  RPS  / mean ~ 30%

28. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos27 Dijet Properties SD boosted opposite to pbar p p jet

29. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos28 Alignment of RPS using Data maximize the |t|-slope  determine X and Y offsets

30. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos29 Diffractive Structure Function: Q 2 dependence E T jet ~ 100 GeV ! Small Q 2 dependence in region 100 < Q 2 < 10,000 GeV 2  Pomeron evolves similarly to proton!

31. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos30 Diffractive Structure Function: t- dependence  No diffraction dips  No Q2 dependence in slope from inclusive to Q 2 ~10 4 GeV 2 Fit d  /dt to a double exponential:  Same slope over entire region of 0 < Q 2 < 10,000 GeV 2 across soft and hard diffraction!

32. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos31 EXCLUSIVE PRODUCTION H Measure exclusive jj &     Calibrate predictions for H production rates @ LHC Bialas, Landshoff, Phys.Lett. B 256,540 (1991) Khoze, Martin, Ryskin, Eur. Phys. J. C23, 311 (2002); C25,391 (2002);C26,229 (2002) C. Royon, hep-ph/0308283 B. Cox, A. Pilkington, PRD 72, 094024 (2005) OTHER………………………… Search for exclusive dijets: Measure dijet mass fraction Look for signal as M jj  1 Search for exclusive  Search for events with two high E T gammas and no other activity in the calorimeters or BSCs KMR:  H (LHC) ~ 3 fb S/B ~ 1 if  M ~ 1 GeV Clean discovery channel

33. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos32 Exclusive Dijet and  Search b-taqged dijet fraction Dijet fraction – all jets Exlusive b-jets are suppressed by J Z = 0 selection rule Excess over MC predictions at large dijet mass fraction Systematic uncertainties under study: tune in soon for results! Exclusive  Based on 3 events observed: Good agreement with KMR: DIJETSDIJETS

34. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos33 Dijets: Data vs MC  Excess of events at high R jj is well described by both exclusive dijet production models  Currently investigating the dependence of the cross section on second jet E T to differentiate between the two models ExHuME (KMR): gg  gg process  uses LO pQCD Exclusive DPE (DPEMC)  non-pQCD based on Regge theory

35. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos34 Exclusive Dijet Signal COMPARISON inclusive data vs MC @ b/c-jet data vs inclusive

36. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos35 Exclusive  ee Search (anti)proton not detected require 2 EM showers (E T >5 GeV, |h|<2 ) veto on all BSCs and all calorimetery except for the 2 EM showers L~530 pb -1 delivered  L effective =46 pb -1  19 events with 2 EM showers + ”nothing” [above threshold] QED process: cross-check to exclusive 

37. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos36  16 candidate events found background: Exclusive ee Search control sample for  search good agreement with LPAIR : E T 1 =6.1 GeV E T 2 =6.0 GeV

38. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos37 Exclusive  Search  3 candidate events found background: good agreement with KMR: E T 1 =6.8 GeV/c E T 2 =5.9 GeV/c   H ~ 10 fb (if H exists) within a factor ~ 2-3, higher in MSSM

39. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos38 Dark Energy P(  y) is exponentially suppressed Rapidity gaps are formed by multiplicity fluctuations: Non-diffractive interactions Rapidity gaps at t=0 grow with  y: Diffractive interactions 2  : negative particle density! Gravitational repulsion ?

40. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos39 Summary TEVATRON – what we have learnt  M 2 – scaling  Non-suppressed double-gap to single-gap ratios  Pomeron: composite object made up from underlying pdf’s subject to color constraints LHC - what to do  High mass (  4 TeV !) and multi-gap diffraction  Exclusive production  Reduced bgnd for std Higgs to study properties  Discovery channel for certain Higgs scenarios

41. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos40 BACKUP

42. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos41 Diffractive DIS: two models e Q2Q2 ** p jet  reorganize probing the proton structure! e **  t p IP Particle-like PomeronColor reorganization what is the Pomeron structure?

43. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos42 Inclusive vs Diffractive DIS  P (0)-1 (  q  )/2 F 2 ~ x  qq KG, “Diffraction: a New Approach,” J.Phys.G26:716-720,2000 e-Print Archive: hep-ph/0001092 Inclusive DIS Inclusive & diffr. DIS

44. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos43 DSF: H1 vs ZEUS CDF H1 Using preliminary pdf’s from Fit including charm data Fit without charm data ZEUS H1 M. Arneodo, HERA/LHC workshop, CERN, 11-13 Oct 2004 Flat after subtracting Reggeon contribution

45. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos44 Diffractive Dijets @ Tevatron p jet reorganize jet  g ~ 0.2  Agreement with data!

46. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos45  -dependence: Inclusive vs Dijet Pomeron dominated

47. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos46 Gap Between Jets Question

48. Low x 2006, Lisbon, Portugal, June 28 – July 2Results from CDF on Diffraction K. Goulianos47 valence quarks antiproton x=x= Diffraction from the Deep Sea 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