1. 1 Forward Proton Tagging at the LHC as a Tool to Study New Physics V.A. Khoze (IPPP, Durham) main aims  to illustrate the theoretical motivations behind the recent proposals to add the Forward Proton Taggers to the LHC experiments.  to show that the Central Exclusive Diffractive Processes may provide an exceptionally clean environment to search for and to identify the nature of new objects at the LHC FP-420

2. 2 1.Introduction (gluonic Aladdin’s lamp) 2.Basic elements of KMR approach (qualitative guide) 3. Prospects for CED Higgs production. the SM case MSSM Higgs sector ( troublesome regions) MSSM with CP-violation. 4.‘Exotics’ 5. The ‘standard candle’ processes.( experimental checks ) 6.Conclusion 7. Ten commandments of Physics with Forward Protons at the LHC. PLAN

3. 3 CMS & ATLAS were designed and optimised to look beyond the SM  High -pt signatures in the central region But… ‘ incomplete’ Main physics ‘goes Forward’ Difficult background conditions. The precision measurements are limited by systematics (luminosity goal of δL ≤5%)  Lack of : Threshold scanning, resolution of nearly degenerate states (e.g. MSSM Higgs sector) Quantum number analysing ILC chartered territory Handle on CP-violating effects in the Higgs sector Photon – photon reactions Is there a way out? ☺ YES-> Forward Proton Tagging Rapidity Gaps  Hadron Free Zones matching Δ Mx ~ δM (Missing Mass ) RG X p p p p talk by A. De Roeck

4. 4 Forward Proton Taggers as a gluonic Aladdin’s Lamp (Old and New Physics menu ) Higgs Hunting ( the LHC ‘core business ’ ) K(KMR)S- 97-04 Photon-Photon, Photon - Hadron Physics ‘Threshold Scan ’: ‘ Light’ SUSY … KMR-02 Various aspects of Diffractive Physics ( soft & hard ). KMR-01 ( strong interest from cosmic rays people ) High intensity Gluon Factory (underrated gluons) KMR-00, KMR-01 QCD test reactions, dijet P-luminosity monitor Luminometry KMOR-01 Searches for new heavy gluophilic states KMR-02, KMRS-04 FPT  Would provide a unique additional tool to complement the conventional strategies at the LHC and ILC.  Higgs is only a part of the broad EW, BSM and diffractive program@LHC wealth of QCD studies, glue-glue collider, photon-hadron, photon-photon interactions … FPT  will open up an additional rich physics menu ILC@LHC Albert De Roeck

5. 5 The basic ingredients of the KMR approach ( Khoze-Martin-Ryskin 1997-2006) Interplay between the soft and hard dynamics B ialas-Landshoff- 9 1 rescattering/absorptive ( Born -level ) effects Main requirements: inelastically scattered protons remain intact active gluons do not radiate in the course of evolution up to the scale M >>/\ QCD in order to go by pQCD book  (CDPE) ~ 10 *  (incl) - 4 RG signature for Higgs hunting ( Dokshitzer, Khoze, Troyan, 1987 ). Developed and promoted by Bjorken (1992-93)

6. 6  (CDPE) ~ 10 *  incl -4 How would you explain it to your (grand) children ?

7. 7 Forcing two (inflatable) camels to go through the eye of a needle High price to pay for such a clean environment : σ (CEDP) ~ 10 -4 σ( inclus. ) R apidity Gaps should survive hostile hadronic radiation damages and ‘ partonic pile-up ‘ W = S² T² Colour charges of the ‘digluon dipole’ are screened only at r d ≥ 1/ (Qt) ch GAP Keepers (Survival Factors), protecting RG against:  the debris of QCD radiation with 1/Qt≥ ≥ 1/M (T)  soft rescattering effects (necessitated by unitariy) (S) H P P How would you explain it to your (grand) children ?

8. 8 Reliability of pred n of  (pp  p + H + p) crucial contain Sudakov factor T g which exponentially suppresses infrared Q t region  pQCD S 2 is the prob. that the rapidity gaps survive population by secondary hadrons  soft physics  S 2 =0.026 (LHC) S 2 =0.05 (Tevatron )  (pp  p + H + p) ~ 3 fb at LHC for SM 120 GeV Higgs ~0.2 fb at Tevatron H

9. 9

10. 10 Possible role of semi-enhanced hard rescattering corrections J. Bartels et al (hep-ph/0601128) KMR (hep-ph/0602247) Enhanced corrections should be small at LHC energies.

11. 11 pp ‘ New Heavy’ States M (S²) γγ = 0.86 (KMR-02 ) α s ²/ 8 we should not underestimate photon fusion ! T² ²²

12. 12 Highlights:  CM energy W up to/beyond 1 TeV (and under control) Large photon flux F therefore significant  luminosity Complementary (and clean) physics to pp interactions, eg studies of exclusive production of heavy particles might be possible opens new field of studying very high energy  (and  p) physics LHC as a High Energy  Collider p p K. Piotrzkowski, Phys. Rev. D63 (2001) 071502(R) J.Ohnemus, T.Walsh & P.Zerwas -94; KMR-02 Very rich Physics Menu

13. 13 Higgs boson REWARD 2.5 billion LHC cost

14. 14 Current consensus on the LHC Higgs search prospects SM Higgs : detection is in principle guaranteed for any mass. ☺ In the MSSM h-boson most probably cannot escape detection, and in large areas of parameter space other Higgses can be found. ☺ But there are still troublesome areas of the parameter space : intense coupling regime of MSSM, MSSM with CP-violation …..  More surprises may arise in other SUSY non-minimal extensions: NMSSM…… After discovery stage ( Higgs Identification ):  The ambitious program of precise measurements of the Higgs mass, width, couplings, and, especially of the quantum numbers and CP properties would require an interplay with a ILC

15. 15 The advantages of CED Higgs production Prospects for high accuracy mass measurements irrespectively of the decay mode. ( H-width and even missing mass lineshape in some BSM scenarios ). Valuable quantum number filter/analyzer. ( 0++ dominance ; C, P- even)  difficult or even impossible to explore the light Higgs CP at the LHC conventionally. (selection rule - an important ingredient of pQCD approach, H ->bb ‘readily’ available (gg) CED  bb LO (NLO,NNLO) BG’s -> studied SM Higgs S/B~3(1GeV/  M ) complimentary information to the conventional studies. For some (troublesome) areas of the MSSM parameter space may become a discovery channel H → WW */ WW - an added value especially for SM Higgs with M≥ 135GeV,  - ‘an advantageous investment’ New run of the MSSM studies is underway (with G. Weiglein et al) New leverage –proton momentum correlations ( probes of QCD dynamics, pseudoscalar ID, CP- violation effects ) KMR-02; J.Ellis et al -05  LHC : ‘after discovery stage’, Higgs ID ……

16. 16 ☻ Experimental Advantages –Measure the Higgs mass via the missing mass technique Mass measurements do not involve Higgs decay products Experimental Challenges –Tagging the leading protons –Selection of exclusive events & backgrounds –Triggering at L1 in the LHC experiments –Model dependence of predictions: (soft hadronic physics is involved after all) – resolve many of the issues with Tevatron data There is still a lot to learn from present and future Tevatron diffractive data (KMRS- friendly so far). Albert De Roeck

17. 17 H b jets : M H = 120 GeV s = 2 fb (uncertainty factor ~2.5) M H = 140 GeV s = 0.7 fb M H = 120 GeV : 10 signal / O(10) background in 30 fb -1 WW * : M H = 120 GeV s = 0.4 fb M H = 140 GeV s = 1 fb M H = 140 GeV : 5-6 signal / O(3) background in 30 fb -1 The b jet channel is possible, with a good understanding of detectors and clever level 1 trigger ( μ-trigger from the central detector at L1 or/and RP(220) +jet condition) The WW channel is extremely promising : no trigger problems, better mass resolution at higher masses (even in leptonic / semi-leptonic channel), weaker dependence on jet finding algorithms The  mode looks advantageous  If we see SM-like Higgs + p- tags  the quantum numbers are 0 ++ Exclusive SM Higgs production (with detector cuts) H optimistically

18. 18 The MSSM and more exotic scenarios If the coupling of the Higgs-like object to gluons is large, double proton tagging becomes very attractive The intense coupling regime of the MSSM (E.Boos et al, 02-03) CP-violating MSSM Higgs physics ( A.Pilaftsis,98; M.Carena et al.,00-03, B.Cox et al 03, KMR-03, J. Ellis et al - 05) Potentially of great importance for electroweak baryogenesis an ‘Invisible’ Higgs (BKMR-04) NMSSM ( with J. Gunion )

19. 19 Theoretical Input

20. 20 (h  SM-like, H/A- degenerate.)

21. 21 (theoretical expectations –more on the conservative side)

22. 22

23. 23 The intense coupling regime is where the masses of the 3 neutral Higgs bosons are close to each other and tan  is large suppressed enhanced 0 ++ selection rule suppresses A production: CEDP ‘filters out’ pseudoscalar production, leaving pure H sample for study M A = 130 GeV, tan  = 50 M h = 124 GeV :71signal / (3-9) background in 30 fb -1 M H = 135 GeV : 124 signal / (2-6) background in 30 fb -1 M A = 130 GeV : 3 signal / (2-6) background in 30 fb -1 Well known difficult region for conventional channels, tagged proton channel may well be the discovery channel, and is certainly a powerful spin/parity filter The MSSM can be very proton tagging friendly

24. 24 decoupling regime m A ~ m H  150GeV, tan  >10; h = SM intense coupl: m h ~ m A ~ m H ,WW.. coupl suppressed with CEDP: h,H may be clearly distinguishable outside 130+-5 GeV range, h,H widths are quite different

25. 25 With CEDP the mass range up to 160-170 GeV can be covered at medium tan  and up to 250 GeV for very high tan , with 300 fb -1 Helping to cover the LHC gap? Needs,however, still full simulation pile-up ?

26. 26 ● H  bb in the high mass range (M A  180-250 GeV) -unique signature for the MSSM, cross-sections overshoot the SM case by orders of magnitude. -possibility to measure the Hbb Yukawa coupling, -nicely complements the conventional Higgs   searches - CP properties, separation of H from A, -unique mass resolution, -may open a possibility to probe the ‘wedge region’ !? -further improvements needed ( going to high lumi ?....) (more detailed theoretical studies required ) ● h, H  bb, in the low mass range (M A < 180 GeV) - coverage mainly in the large tan  and low M A region, -further improvements (trigger efficiency….) needed in order to increase coverage - Ongoing studies (together with S. Heinemeyer, M.Ryskin, W..J. Stirling, M.Tasevsky and G. Weiglein)

27. 27 mhmax scenario,  =200 GeV, M SUSY =1000 GeV h  bb PRELIMINARY

28. 28 H  bb PRELIMINARY

29. 29 ● h, H   in the low mass range (M A <180 GeV) -essentially bkgd –free production, -need further improvements, better understanding.., -possibility to combine with the bb-signal (trigger cocktail …) -can we trigger on  without the RP condition ? ● h  WW -significant (~4) enhancement as compared to the SM case in some favourable regions of the MSSM parameter space. ● small and controllable backgrounds ● Hunting the CP-odd boson, A a way out : to allow incoming protons to dissociate (E-flow ET>10-20 GeV) KKMR-04 pp  p + X +A +Y +p  At the moment the situation looks borderline

30. 30 small  eff scenario for the SM Higgs at M = 120 GeV  = 0.4 fb, at M= 140 GeV  = 1 fb m h  121-123 GeV h  WW PRELIMINARY

31. 31 Current understanding of the bb backgrounds for CED production  for reference purposes SM (120 GeV)Higgs in terms of S/B ratio ( various uncrt. cancel)  First detailed studies by De Roeck et al. ( DKMRO-2002 )  Preliminary results and guesstimates – work still in progress S/B  1 at ΔM  4 GeV Four main sources (~1/4 each)  gluon-b misidentification (assumed 1% probability) Prospects to improve in the CEDP environment ? Better for larger M.  NLO 3-jet contribution Correlations, optimization -to be studied.  admixture of |Jz|=2 contribution  b-quark mass effects in dijet events Further studies of the higher-order QCD in progress

32. 32  The complete background calculations are still in progress (unusually large high-order QCD and b-quark mass effects).  Optimization, MC simulation- still to be done Mass dependence of the  SM ( CEDP ): S H ~1/M³ Bkgd :ΔM/M for , ΔM/M for  ( ΔM,triggering, tagging etc improving with rising M) 6 8

33. 33 MS MSSM PRELIMINARY V.A.Khoze, S.Heinemeyer, W.J.Stirling, M.Ryskin,M. Tesevsky and G. Weiglein in progress

34. 34 MS MSSM PRELIMINARY V.A.Khoze, S.Heinemeyer, W.J.Stirling, M.Ryskin,,M. Tesevsky and G. Weiglein in progress

35. 35 MSSM V.A.Khoze, S.Heinemeyer, W.J.Stirling, M.Ryskin M. Tesevsky and G. Weiglein in progress PRELIMINARY

36. 36 Spin Parity Analysis Azimuthal angle between the leaprotons depends on spin of H Measure the azimuthal angle of the proton on the proton taggers Azimuthal angle between the leading protons depends on spin of H  angle between protons  angle between protons with rescattering effects included KKMR -03 0 0 - +

37. 37 CP even CP odd active at non-zero t Azimuthal asymmetry in tagged protons provides direct evidence for CP violation in Higgs sector Probing CP violation in the Higgs Sector ‘CPX’ scenario (  in fb) KMR-04 A is practically uPDF - independent Results in tri-mixing scenaio (J.Ellis et al) are encouraging, (KMR in progress)

38. 38 Hunting the CP-odd boson, A

39. 39 Hunting the CP-odd boson, A  (LO) selection rule – an attractive feature of the CEDP processes, but ……  the flip side to this coin: strong ( factor of ~ 10² )suppression of the CED production of the A boson.  A way out : to allow incoming protons to dissociate (E-flow E T>10-20 GeV ) KKMR-04 pp  p + X +H/A +Y +p (CDD) in LO azim. angular dependence: cos²  (H), sin²  (A), bkgd- flat  challenges: bb mode – bkgd conditions  -mode- small (QED)bkgd, but low Br A testing ground for CP-violation studies in the CDD processes (KMR-04)

40. 40  within the (MS) MSSM, e.g. mh scenarios with  = ±200 (500) GeV, tan  =30-50  CDD (A->bb) ~ 1-3 fb,  CDD (A->  ) ~ 0.1-03 fb  CDD (H)~-  CDD (A) max bb mode –challenging bkgd conditions (S/B ~1/50).  -mode- small (QED) bkgd, but low Br situation looks borderline at best  ‘best case’ ( extreme ) scenario mh with  =- 700 GeV, tan  =50, m g =10³GeV max CDD results at  (RG) >3, E T >20 GeV

41. 41 A A  in this extreme case :  (A  gg) Br(A  bb)  22-24 MeV at M A = 160-200 GeV,tan   50,  CDD (A  bb) is decreasing from 65fb to 25fb (no angular cuts)   CDD (A   )  0.8-0.3 fb S/B ~  (A->gg) Br (A->bb) /  M CD  5.5 /  M CD (GeV) currently  M CD ~ 20-30 GeV… (  12GeV at 120 GeV) Prospects of A- searches strongly depend, in particular, on the possible progress with improving  M CD in the Rap. Gap environment There is no easy solution here, we must work hard in order to find way out. We have to watch closely the Tevatron exclusion zones

42. 42 Proton Dissociative Production (experimental issues) thanks to Monika, Michele & Albert  Measurement of the proton diss. system with E T of 20 GeV and 3<  <5 -probably OK for studying the azimuthal distributions (HF or FCAL calorimeters)  Trigger is no problem if there is no pile up (Rap Gaps at Level 1); 4jet at 2*10³³ lumi- borderline Maybe we can think about adding RPs into the trigger ( no studies so far) Maybe neutrons triggered with the ZDC (Michele )? Can we discriminate between the cos²  and sin²  experimentally ?  From both the theoretical and experimental perspectives the situation with searches for the A in diffractive processes looks at best borderline, but the full simulation should be performed before arriving at a definite conclusion.

43. 43 … the LHC as a ‘gluino factory’, N. Arkani-Hamed ( Pheno-05) BFK-92 KMR-02 pp  pp + ‘nothing’ further progress depends on the survival ….

44. 44 an ‘Invisible ‘ Higgs KMR-04 several extensions of the SM : a fourth generation some SUSY scenarios, large extra dimensions (one of the ‘LHC headaches’ ) the advantages of the CEDP – a sharp peak in the MM spectrum, mass determination, quantum numbers strong requirements : triggering directly on L1 on the proton taggers low luminosity : L= 10 ³² -10 ³³ cm - 2 sec -1 (pile-up problem), forward calorimeters (…ZDC) (QED radiation, soft DDD), v eto from the T1, T2- type detectors (background reduction, improving the trigger budget)  various potential problems of the FPT approach reveal themselves  however there is a (good) chance to observe such an invisible object, which, otherwise, may have to await a ILC  searches for extra dimension – diphoton production (KMR-02) H

45. 45 EXPERIMENTAL CHECKS  Up to now the diffractive production data are consistent with K(KMR)S results Still more work to be done to constrain the uncertainties Very low rate of CED high-Et dijets, observed yield of Central Inelastic dijets. (CDF: Run I, Run II) data up to (E t)min >50 GeV ‘ Factorization breaking’ between the effective diffractive structure functions measured at the Tevatron and HERA. (KKMR-01,a quantitative description of the results, both in normalization and the shape of the distribution) The ratio of high Et dijets in production with one and two rapidity gaps Preliminary CDF results on exclusive charmonium CEDP. Higher statistics is underway. Energy dependence of the RG survival (D0, CDF) CDP of γγ (in line with the KMRS calculations) BREAKING NEWS, CDF

46. 46 “ standard candles ” First experimental results are encouraging, new data are underway

47. 47

48. 48 Tevatron vs HERA: Factorization Breakdown dN/d  gap dN/d  gap pp IP CDF H1 pp IP e **  t p IP p well

49. 49

50. 50

51. 51 KMR expectations CDF exclusive di-jet limits H-mass range

52. 52 DIS04 KMR-01, 70 pb 47 pb CHIC

53. 53 pp  p + γγ + p KMRS-04

54. 54 BREAKING NEWS

55. 55 (KMR/ExHume)

56. 56

57. 57 of Forward Proton Tagging 1. Thou shalt not worship any other god but the First Principles, and even if thou likest it not, go by thy Book. 2. Thou slalt not make unto thee any graven image, thou shalt not bow down thyself to them. 3.Thou shalt treat the existing diffractive experimental data in ways that show great consideration and respect. 4. Thou shalt draw thy daily guidance from the standard candle processes for testing thy theoretical models. 5. Thou shalt remember the speed of light to keep it holy. ( trigger latency ) 6. Thou shalt not dishonour backgrounds and shalt study them with great care. QCD

58. 58 9. Thou shalt not annoy machine people. 10. Thou shalt not delay, the LHC start-up is approaching 7.Thou shalt not forget about the pile-up (an invention of Satan). 8. Though shalt not exceed the trigger thresholds and the L1 saturation limit. Otherwise thy god shall surely punish thee for thy arrogance.

59. 59 CONCLUSION  Forward Proton Tagging would significantly extend the physics reach of the ATLAS and CMS detectors by giving access to a wide range of exciting new physics channels.  FPT has the potential to make measurements which are unique at LHC and challenging even at a ILC. For certain BSM scenarios the FPT may be the Higgs discovery channel within the first three years of low luminosity running  FPT offers a sensitive probe of the CP structure of the Higgs sector. Nothing would happen before the experimentalists & engineers come FORWARD and do the REAL WORK. The R&D studies must be completed within 12 months (only limited time-scale and manpower available)

60. 60 From the LHCC minutes (November 2005) The LHCC heard a report from the FP420 referee. In its Letter of Intent,the FP420 Collaboration puts forward an R&D proposal to investigate the feasibility of installing proton tagging detectors in the 420 m. region at the LHC. By tagging both outgoing protons at 420 m. a varied QCD,electroweak, Higgs and Beyond the Standard Model physics programme becomes accessible. A prerequisite for the FP420 project is to assess the feasibility of replacing the 420 m. interconnection cryostat to facilitate access to the beam pipes and therefore allow proton tagging detectors to be installed. The LHCC acknowledges the scientific merit of the FP420 physics program and the interest in its exploring its feasibility. LOI-submitted to the LHCC: CERN-LHCC-2005-025 LHCC-I-015 FP420 : An R&D Proposal to Investigate the Feasibility of Installing Proton Tagging Detectors in the 420m Region at LHC. FP420 (58 physicists from 29 institutes in 11 countries) Sub-detectors of either or both of ATLAS & CMS (common R&D route). First opportunity –autumn 2008 (planned LHC shutdown) FP420 detector will replace the 420m interconnection cryostat

61. 61 FP-420 The LHC start-up is approaching