Exclusive Diffraction at HERA Henri Kowalski DESY Ringberg October 2005

1. Exclusive Diffraction atHERAHenri KowalskiDESY RingbergOctober 2005

2. F2 is dominated by single ladder exchange ladder symbolizes the QCD evol. process ( DGLAP or others )

3. Gluon density Gluon density dominates F2 for x < 0.01

4. Diffractive Scattering Non-Diffractive Event ZEUS detector Diffractive Event MX - invariant mass of all particles seen in the central detector t - momentum transfer to the diffractively scattered proton t - conjugate variable to the impact parameter

5. Diffractive Signature diff Non- diff ~ DY= log(W2/M2X) Non-Diffraction Diffraction - Rapidity uniform, uncorrelated particle emission along the rapidity axis => probability to see a gap DY is ~ exp(-<n>DY) <n> - average multipl. per unit of Y dN/dM2X ~ 1/M2X => dN/dlog M2X ~ const

6. Observation of diffraction indicates that single ladder may not be sufficient (partons produced from a single chain produce exponentially suppressed rap. gaps) Diffractive Structure Function Dipole Model ______________ Initial Diff. SF Q20 ~ 4 GeV2 Study of exclusive diffractive states may clarify which pattern is right Only few final states present in DiMo: qq, qqg (aligned and as jets) VM

7. Dipole description of DIS equivalent to Parton Picture in the perturbative region momentum space configuration space dipole preserves its size during interaction. sqq ~ r2xg(x,m) for small r er<<1 Q2~1/r2 Optical T Mueller, Nikolaev, Zakharov

8. Dipole description of DIS GBW – first Dipole Saturation Mode (rudimentary evolution) Golec-Biernat, Wuesthoff BGBK – DSM with DGLAP Bartels, Golec-Biernat, Kowalski Iancu, Itakura, Munier - BFKL-CGC motivated ansatz Forshaw and Shaw - Regge ansatz with saturation

9. Kowalski Teaney Impact Parameter Dipole Saturation Model b – impact parameter Glauber-Mueller, Levin, Capella, Kaidalov… T(b) - proton shape

10. Total g*p cross-section universal rate of rise of all hadronic cross-sections x < 10-2

11. Ratio of stot to sdiff from fit to stot predict sdiff GBW, BGBK … sdiffis not a square ofstot !

12. _ Diffractive production of a qq pair ~ probability to find a Pomeron(2g) in p ~ probability for a Pomeron(2g) to couple to a quark

13. spin 1/2 spin 1 s ~ sa-1 => dN/dlog M2X ~ const

14. Diffractive production of a qqg state

15. Inclusive Diffraction LPS — BGBK Dipole

16. Comparison with Data FS modelwith/without saturation and IIMCGC model hep-ph/0411337. Fit F2 and predict xIPF2D(3) FS(nosat) F2 CGC FS(sat) F2 x

17. Dipole cross section determined by fit to F2 Simultaneous description of many reactions F2 C Gluon density test? Teubner IP-Dipole Model g*p -> J/y p g*p -> J/y p IP-Dipole Model

20. Exclusive r production

23. Modification by Bartels, Golec-Biernat, Peters, (first proposed by Nikolaev, Zakharov)

24. H. Kowalski, L. Motyka, G. Watt preliminary

25. Diffractive Di-jets Q2 > 5 GeV2 -RapGap Satrap

26. Diffractive Di-jets Q2 > 5 GeV2

27. Diffractive Di-jets Q2 > 5 GeV2

31. Diffractive Di-jets at the Tevatron Dijet cross section factor 3-10 lower than expected using HERA Diffractive Structure Functions suppression due to secondary interactions ?

32. H1 and ZEUS: NLO overestimates data by factor 1.6. Kaidalov et al.: resolved part needs to be rescaled by 0.34

33. scaled by factor 0.34

34. Survival Probability S2 Soft Elastic Opacity t – distributions at LHC Effects of soft proton absorption modulate the hard t – distributions Khoze Martin Ryskin Dipole form double eikonal t-measurement will allow to disentangle the effects of soft absorption from hard behavior single eikonal

35. ZEUS-LPS

36. H1 VFPS at HERA

37. Conclusions Inclusive diffraction, exclusive diffractive VM and jet production can be successfully derived from the measured F2 (Dipole Model with u. gluon densities obtained from F2 ) Detailed VM-data from HERA should allow to pin down VM wave functions Diffractive Structure Function analysis describes well the inclusive diffractive processes and the exclusive diffractive jet production although it has some tendency to amplify small differences of the input distributions Exclusive diffractive processes give detailed insight into DIS dynamics

38. Press Release: The 2005 Nobel Prize in Physics 4 October 2005 The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Physics for 2005 with one half to Roy J. GlauberHarvard University, Cambridge, MA, USA "for his contribution to the quantum theory of optical coherence"

39. Glauber wrote his formula for heavy nuclei and for deuteron. He was the first who realized that his formula in the case of deuteron describes both the elastic cross section and the diffractive dissociation of the deuteron. Genya Levin

40. Roy Glauber’s Harvard Webpage Roy Glauber's recent research has dealt with problems in a number of areas of quantum optics, a field which, broadly speaking, studies the quantum electrodynamical interactions of light and matter. He is also continuing work on several topics in high- energy collision theory, including the analysis of hadron collisions, and the statistical correlation of particles produced in high-energy reactions. Specific topics of his current research include: the quantum mechanical behavior of trapped wave packets; interactions of light with trapped ions; atom counting-the statistical properties of free atom beams and their measurement; algebraic methods for dealing with fermion statistics; coherence and correlations of bosonic atoms near the Bose-Einstein condensation; the theory of continuously monitored photon counting-and its reaction on quantum sources; the fundamental nature of “quantum jumps”; resonant transport of particles produced multiply in high-energy collisions; the multiple diffraction model of proton-proton and proton-antiproton scattering

41. Saturation and Absorptive corrections - F2 ~ Single inclusive linear QCD evolution Diffraction Example in Dipole Model High density limit —> Color Glass Condensate McLerran coherent gluon stateVenogopulan

42. 2-Pomeron exchange in QCD Final States (naïve picture) 0-cut Diffraction 1-cut <n> 2-cut <2n>

43. QCD diagrams

45. AGK rules in the Dipole Model Note: AGK rules underestimate the amount of diffraction in DIS

47. GBW Model IP Dipole Model less saturation (due to IP and charm) strong saturation

48. Saturation scale (a measure of gluon density) HERA RHIC QSRHIC ~ QSHERA

49. Geometrical Scaling A. Stasto & Golec-Biernat J. Kwiecinski

50. Geometrical Scaling can be derived from traveling wave solutions of • non-linear QCD evolution equations • Velocity of the wave front gives the energy dependence of the saturation scale • Munier, Peschanski • L. McLerran +… • Al Mueller + .. • Question: • Is GS an intrinsic (GBW) or effective (KT) property of HERA data? Dipole X-section ——BGBK ---- GBW