DIFFRACTION and Forward Physics – 2

1. DIFFRACTION and Forward Physics–2 M. Arneodo, M.Diehl, V.A.Khoze, P.Newman & with a bit of personal flavour Plan • 1. New theoretical results presented at the 4th Workshop • 2. Selectedhot topics: • survival of the survival factor, • basic soft cross-sections at the LHC • 3. What can HERA still provide ? • 4. Selected early LHC measurements to test predictions • for diffractive processes • Apologies to those excellent & enthusiastic speakers, • whose results were not (properly) covered • (lack of time or / and expertise) by popular demand

2. Theory Talks (-part) Selection: -as seen through the eyes of the needs of Forward Prhusics Community -minimal overlap with other WGs some overlap :SATURATION  JB– nontrivial task of transferring a theoretical description of saturation from HERA to the LHC K G-B, GW –sensitivity of the Diffractive DIS to the saturation sat. effectsquantified- GW

3. CMS Near beam Detectors p p Photon-photon and photon-proton collider @ LHC (P. Bussey, J. Nystrand) Process WWA spectrum • Extensive Program •   , ee QED processes •   QCD (jets..) •   WW anomalous couplings •   squark, top… pairs •   BSM Higgs •   Charginos • … …and p

4. LHC as a High Energy  Collider KMR-02

5. (P. Bussey ) γγPHOTOPRODUCTION Cross sections for various γγprocesses. The dimuon process may be good for LHC luminosity monitoring. W+W- has a large cross section of 100 fb.

6. Recently -renewal of the interest BAD NEWS KMR-02

7. Exclusive Channels in pp -collisions G. Watt, L.Motyka, A.Martin, J.Nystrand in a peaceful coexistence exclusive J/ from HERA data as an independent source of information on unintegr. gluons, needed for theH-Central Excl. Higgs Production (TT,GW) (GW, LM, JN) Exclusive U production at the LHC as probe of unintegrated gluons (GW, AM) Give us unintegrated gluons in advance (P.Bussey ) a nice way to search for the Odderon ( LM, AM, JN) a potential discovery channel

9. (L. Motyka, A.Martin) odderon exch g exch (ALICE, LHCb) (R. Schicker, , J/ - RG)

10. G. Watt, L.Motyka (good agreement with J.Nystrand and KMR ) (“blessed”) (J. Pinfold)

11. Selected Hot Topics conflict of interests Importance for the Forward Physics Studies at the LHC Serve as a litmus paper indicator of the level of our knowledge (theory & experiment) on diffractive physics at high energies Survival of the Survival Factor (Regular talks by U. Maor (GLM), A. Martin (KMR) and M. Strikman (FHSW)) Account for the absorption effects -necessitated by unitarity S² -a crucial ingredient of the calculations of the rate of the Central Excl. Diffractive processes +….. Prospects of New Physics studies in the Forward Proton mode qualitativelynew stage –a ‘delivery’ of our meetings •orders of magnitude differences in theoretical expectations – are a history (not so long ago-between Scylla and Charybdis) • new (encouraging) CED Tevatron results available, more results to come (K. Goulianos, J. Pinfold) • we are discussing now the differences on the level of a factor of (4-5) (M. Strikman)

12. (K . Goulianos) arXiv:0712.0604 , PRD to appear soon A killing blow to the wide range of theoretical models.

13. PT LO undisputable

14. FHSW weak (~1/2) suppression (a factor of 4-5 diff. ) (M. Strikman) it might be much worse

15. Approach to the Black Disc Regime (how rapid is it above 2 TeV ?) START: at  2 TeV FINISH: BDR, =1 1.KMR  slow (logarithmic) rise byfew % at the LHC 2. FHSW BDR for energies  2 TeV (soft interactions and harddipole-proton int. up to ) 3. GLM(M) two components : ‘conservative’ + BDR-like

16. (tot) , (el) , (SD) Bread and butter of TOTEM and ALFA measurements Importance forvarious LHC studies ( e.g. notorious Pile-Up) Low mass SD (DD)- one of the major current limitations on the models ( still not sufficient exp. Information) KMR-07, A. Martin: relatively low (about 20% below the ‘standard’ central value)value of (tot) at the LHC ( S.Sapeta and K. Golec-Biernat-05) , (tot) 90 mb…cosmic rays, (early) LHC tests – coming soon inescapable consequence of the absorptive corrections caused by the higher-mass excitations (A.Martin) GLM (arXiv; 0805.0418):(tot ) =110.5 mb, (el) =25.3 mb  (GLM)M (arXiv; 0805.2799):(tot ) = 92,1 mb, (el) =20.9 mb KMR(A.Martin)(tot ) =90.5 mb, (el) =20.8 mb GLM(M)- essential improvement of their description of the Tevatron elastic and SD data

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18. Selection Criteria for the Models of Soft Diffraction We have to be open-eyed when the soft physics is involved. Theoretical models contain various assumptions and parameters. Available data on soft diffraction at high energies are still fragmentary, especially concerning the (low mass) diffractive dissociation.   A viable model should: incorporate the inelastic diffraction :SD, DD (for instance 2-3 channel eikonal of KMR or GLM(M)) describe all the existing experimental data on elastic scattering and SD ,DD and CED at the Tevatron energies and below (A. Martin; GLM(M), 0805.2799 ) be able to explain the existing CDF data on the HERA-Tevatron factorization breaking and on the CED production of the di-jets, di-photons, , J/, .., lead. neutr. at HERA provide testable pre-dictions or at leastpost-dictionsfor the Tevatron and HERA So far KMR model has passed these tests. Only a large enough data set would impose the restriction order on the theoretical models and to create a full confidence in the determination of S². Program of Early LHC measurements (KMR, A. Martin) LET THE DATA TALK !

19. What can HERA still provide ? (From DIS08) test higher twists t- depencences (VM, (V)FPS Odderon searches

20. More detailed data on proton dissociation in diffractive J/ production (better statistics, M²-slicing). Improved statistics on exclusive - production (not sufficient at the moment). The ratio of diffractive to exclusive dijets, photo to electroproduction. Transverse momentum distribution of secondaries in the ‘Pomeron fragmentation’.

21. The Extraction of the Bare Triple-Pomeron Vertex Existing (ZEUS) data on J/ -still fragmentary Needed: - improved statistics; -distributions over M²Y -inelast. diffractive  data; small size- component (small rescatter. effects) (dress code) • a crucial ingredient for understanding diffraction (e.g. S²calc.)  Bare  A way to extract the information on  KMR-06 (by integration over ZEUS range) (after acconting for the second. traject.) 0.2 (A. Martin)  Importance of an explicit measurement of the Y-system mass spectrum. To perform a full triple-Regge analysis with different contributions quantified.

23. (A. Martin) Are the early LHC runs, without proton taggers, able to check estimates for pp  p+A+p ? gap gap KMR: 0802.0177 Possible checks of: (i) survival factor S2:W+gaps, Z+gaps (ii) generalised gluon fg : gp Up Divide et Impera (iii) Sudakov factor T : 3 central jets (iv) soft-hard factorisation #(A+gap) evts (enhanced absorptive corrn)#(inclusive A) evts with A = W, dijet, U…

24. LHC with 220m and 420m Forward Taggers High sensitivity to the parameters of models for Soft Diffraction y=-ln , =(1-x) TOTEM, ALFA, ALICE (RG) ?

26. Backup

27. (M.Strikman)

28. Watt S2 ~ 0.02 (A. Martin)

29. Exposing the contribution of the Perturbative Pomeron to DDIS (G. Watt, A.Martin and M. Ryskin (2006)) The perturbative .resolved Pomeron contribution. Nonperturbative resolved Pomeron. Measurements of the kt of secondaries in the ‘Pomeron fragmentation’ (edge of LRG). The kt distribution of the lowest jet should obey the power law – in marked contrast with the expectations based on Regge-factorization. Larger kt of the secondaries with the long power-like tail should be observed.

32. P. Bussey