Exclusive Diffractive Higgs production and Related Processes

1. 6 May 2005 Exclusive Diffractive Higgs production and Related Processes (the key selling points for forward proton tagging at the LHC) To discuss the Standard Candle Processes at the Tevatron for the theoretical prediction

2. 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 • ILC chartered territory • Quantum number analysing • Handle on CP-violating effects in the Higgs sector • Photon – photon reactions p p p RG Is there a way out? ☺YES-> Forward Proton Tagging Rapidity Gaps  Hadron Free Zones Δ Mx ~δM (Missing Mass) X RG p p M. Albrow, A.Rostovtsev -00

3. PLAN • 1. Introduction • (a gluonic Aladdin’s lamp) • 2.Basicelements of Durham approach • (a qualitative guide) • 3. Prospects for CED Higgs production. • the SM case • MSSM Higgses in the troublesome regions • MSSM with CP-violation • Exotics • 5. Experimental checks • 6. Conclusion • 6. Ten commandments of Physics with • Forward Protons at the LHC • .

4. Forward Proton Taggersas a gluonicAladdin’s Lamp • (rich Old and NewPhysics menu) • Higgs Hunting(the LHC ‘core business’) K(KMR)S- 97-04 • Photon-Photon, Photon - HadronPhysics • J.Ohnemus ,T.Walsh, P.Zerwas-93 ,KMR-02, K.Piotrzkowski • ‘Threshold Scan’: ‘Light’ SUSY , tt...KMR-02 • Various aspects of DiffractivePhysics (soft & hard ).KMR-01 • (strong interest from cosmic rays people) • LuminometryKMOR-01 , K.Piotrzkowski • High intensityGluon Factory. KMR-00, KMR-01 • QCD test reactions, dijet luminosity monitor • Searches for new heavy gluophilic statesKMR-02 • FPT •  Would provide a unique additional tool tc complement the conventionalstrategies at theLHCandILC. Higgs is only a part of a broad diffractiveprogram@LHC FPT  an additionalphysics menu inILC@LHC

5. The basic ingredients of the KMR approach(1997-2005) Interplay between the soft and hard dynamics Sudakov suppression • Bialas-Landshoff-91 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 • <Qt> >>/\QCDin order to go by pQCD book (A. Berera & J.Collins-96 ) -4 (CDPE) ~ 10 * (incl)

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

7. High price to pay for such aclean environment: σ (CEDP) ~ 10 -4 σ( inclus.) Rapidity Gapsshould survive hostile hadronic radiation damages and ‘partonic pile-up ‘ W = S² T² • Colour charges of the ‘digluon dipole’ are screened • only at rd ≥ 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) Forcing two (inflatable) camels to go through the eye of a needle H P P

8. schematically skewed unintegrated structure functions (suPDF) (x’~Qt/√s) <<(x~ M/√s) <<1 (Rg=1.2 at LHC) T(Qt,μ)is the probability that a gluon Qt remains untouched in the evolution up to the hard scale M/2 T + anom .dim. → IR filter ( theapparent divergency in the Qt integration nullifies) <Qt>SP~M/2exp(-1/αs),αs =Nc/παsCγ SM Higgs, <Qt>SP ≈ 2 GeV>> ΛQCD

9. MAIN FEATURES • An important role of subleading terms in fg(x,x’,Qt²,μ²), • (SL –accuracy). • Cross sectionsσ~(fg )(PDF-democracy) • S²KMR=0.026 (± 50%)SM Higgs at LHC • (detailed two-channel eikonal analysis of soft pp data) • surprisingly goodagreement with other ‘unitarizer’sapproaches andMCs. • S²/b² - quite stable (within 10-15%) • S²~ s(Tevatron-LHC range) • dL/d(logM² ) ~ 1/ (16+ M) • a drastic role of Sudakov suppression(~ 1/M³) • σH ~ 1/M³ , (σB) ch ~ Δ M/ M 4 ^ ^ ^ ^ -016 3.3 6 • Jz=0 ,even P-selection rule forσis justified • only if <pt>² /<Qt>² « 1 (J. Pumplin-95)

10. pp ‘NewHeavy’ States M QCD-’radiation damages’ T² αs²/8 ² (S²)γγ =0.86 (KMR-02) we should not underestimate photon fusion ! .

11. The advantages of CED Higgs production • Prospects for high accuracy mass measurements • (ΓHand even lineshape in some MSSM scenarios) • mass windowM = 3 ~ 1 GeV (the wishlist) • ~4 GeV(currently feasible) • Valuable quantum number filter/analyzer. • ( 0++dominance ;C , P-even) • difficult or even impossible to explore the light HiggsCPat the LHC conventionally. • (an important ingredient of pQCD approach, • otherwise, large|Jz|=2 …effects, ~(pt/Qt)2!) • H ->bb ‘readily’ available • (gg)CED bbLO (NLO,NNLO)BG’s -> studied • SM HiggsS/B~3(1GeV/M) • complimentary information to the conventional studies( also ՇՇ) • H →WW*/WW - an added value • especially for SM Higgs with M≥ 135GeV,MSSMat l owtanβ • New leverage –proton momentum correlations • (probes of QCD dynamics, pseudoscalar ID, • CP violation effects)KMR-02 (Helsinki group)

12. ☻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 some/many of the issues with Tevatron data There is a lot to learn from present and future Tevatron diffractive data

13. Current consensus on the LHC Higgs • search prospects • (e.g, A.Djouadi, Vienna-04; G.Weiglein, CMS, 04; A.Nikitenko,UK F-m,04)) • SM Higgs : detection is in principle guaranteed ☺ • for any mass. • In the MSSMh-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, • MSSM with CP-violation….. • More surprises may arise in other SUSY • non-minimal extensions • After discovery stage(Higgs identification): • The ambitious program of precise measurements of the mass, width, couplings, • and, especially of the quantum numbers and • CP properties would require an interplay • with a ILC

14. SM Higgs Cross Section * BR • Cross sections~O(fb) • Diffractive Higgs mainly studied for Hbb -K(KMR)97-04 • -DKMOR-02 • Boonekamp et al. ,01-04 SM Higgs • Petrov et al. ,04 •  Recently study extended • for the decay into WW*,WW • can reach higher masses • ‘Leptonic trigger cocktail’ • (WW,bb,ZZ,) • FT420UK team Note, Hbb (120 GeV) at Tevatron  0.13 fb

15. Exclusive SM Higgs production b jets : MH = 120 GeV s = 2 fb (uncertainty factor ~2.5) MH = 140 GeV s = 0.7 fb MH = 120 GeV :11 signal / O(10) background in 30 fb-1 (with detector cuts) H WW* : MH = 120 GeV s = 0.4 fb MH = 140 GeV s = 1 fb MH = 140 GeV :8 signal / O(3) background in 30 fb-1 (with detector cuts) • The b jet channel is possible, with a good understanding of detectors and clever level 1 trigger (needs trigger from the central detector at Level-1) • The WW* (, ZZ*…) 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 • If we see SM-like Higgs + p- tags the quantum numbers are 0++ H

16. ☺An added value of the WW channel 1. ‘less demanding’ experimentally (trigger and mass resolution requirements..) allows to avoid the potentially difficult issue of triggering on the b-jets 2. higher acceptances and efficiencies 3. an extension of well elaborated conventional program, (existing experience, MC’s…) 4. the decrease in the cross section is compensated for by the increasing Br and increased detection efficiency 5. missing mass resolution improves as MH increases 6. the mass measurement is independent of the decay products of the central system 7. Better quantitative understanding of backgrounds. Very low backgrounds at high mass. 8.0+ assignment and spin-parity analyzing power - still hold ☻we should not ignore MSSM with low tan β

17. B. Cox, DIS-05 The Benchmark process : SM Higgs production Preliminary B.C., A. De Roeck, V. A. Khoze, ,W. J. Stirling et. al. To be published

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)

19. (a )The intense coupling regime • MA≤ 120-150GeV, tanβ>>1( E.Boos et al,02-03) • h,H,A- light, practically degenerate • largeΓ, must be accounted for • the ‘standard’ modes WW*,ZZ*, γγ…-strongly suppressed v.s. SM • maybe the best bet – μμ -channel, • in the same time – especially advantageous forCEDP: ☺ • (KKMR 03-04) • σ(gg ->Higgs)Br(Higgs->bb) - significantly exceeds SM. • thus ,much larger rates. • Γh/H~ ΔM, • 0- is filtered out, and the h/H separation may • be possible • (b) The intermediate regime: MA ≤ 500 GeV, • tan β< 5-10 • (the LHC wedge, windows) • (c) The decoupling regime • MA>> 2MZ(in reality, MA>140 GeV, tan β>10) • h is SM-like, H/A -heavy and approximately degenerate, • CEDP may allow to filterAout ~

20. suppressed enhanced The MSSM can be very proton tagging friendly The intense coupling regime is where the masses of the 3 neutral Higgs bosons are close to each other and tan  is large 0++ selection rule suppresses A production: CEDP ‘filters out’ pseudoscalar production, leaving pure H sample for study MA = 130 GeV, tan b = 50 Mh = 124 GeV :71signal / (3-9) background in 30 fb-1 MH = 135 GeV :124 signal / (2-6) background in 30 fb-1 MA = 130 GeV :3 signal / (2-6) background in 30 fb-1 for 5 ϭ BR(bb) > 0.7fb (2.7fb) for 300 (30fb-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

21. decoupling regime: mA ~ mH large h = SM intense coupl: mh ~ mA ~ mH ,WW.. coupl suppressed • with CEDP: • h,Hmay be • clearlydistinguishable • outside130+-5 • GeV range, • h,Hwidths are quite different

22. Helping to cover the LHC gap? needs update 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 Needs ,however, still full simulation

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

24. Probing CP violation in the Higgs Sector Azimuthal asymmetry in tagged protons provides direct evidence for CP violation in Higgs sector ‘CPX’ scenario (s in fb) KMR-04 A is practically uPDF - independent CP odd active at non-zero t CP even

26. CP- violating MSSM with large tri-mixing J.Ellis et al 05 tanβ=50, MH+=150 GeV In thetri-mixing scenario we expectϭbb ~ 1fb and proton asymmetries A ~0.1-03

27. X M 1 GeV Summary of CEDP • The missing mass method may provide unrivalled Higgs mass resolution • Real discovery potential in some scenarios • Very clean environment in which to identify the Higgs,for example, in the CPX or tri-mixing scenarios • Azimuthal asymmetries may allow direct measurement of CP violation in Higgs sector • Assuming CP conservation, any object seen with 2 tagged protons has positive C parity, is (most probably) 0+, and is a colour singlet e.g. mA = 130 GeV, tan b = 50 (difficult for conventional detection, but exclusive diffractive favourable) L = 30 fb-1 S B mh = 124.4 GeV 71 3 events mH = 135.5 GeV 124 2 mA = 130 GeV 1 2 WW*/WW modes are looking extremely attractive.

28. …the LHC as a ‘gluino factory’ , N. Arkani-Hamed( Pheno-05) BFK-92 KMR-02 pp  pp + ‘nothing’(215 m ?)

29. an ‘Invisible ‘ HiggsKMR-04 M.Albrow & A .Rostovtsev -00 • 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 directlyon L1 on the proton taggers • low luminosity : L= 10³² -10³³cm-2 sec-1 (pile-up problem) , • forward calorimeter(…ZDC) (QED radiation , soft DDD), • veto from the T1, T2- type detectors (background reduction, improving the trigger budget) various potential problems of the FPT approach reveals 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)

30. 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 (Et)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 shapeof 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, data are underway • KKMR .….. has still survived theexclusion limits • set by the Tevatron data….(M.Gallinaro, hep-ph/01410232)

31. p x,t IP IP IP p p p p g* H1 e CDF gap gap dN/dh dN/dh Tevatron vs HERA:Factorization Breakdown p (K.G0ulianos, PLB 358 (1995) 379) well

32. Exclusive Dijets in Run I ) KMR-00 rejection of ‘optimistic’ theoretical models e+e- -> jj with similar jet selection

33. Exclusive Dijet production from CDF2LHC M. Gallinero (hep-ph/0504025) ~1 nb, KMR-00 ~40pb, KMRS-04 KMR model,‘at the time of writing has still survived the exclusive limits set by the Tevatron data ‘ M. Gallinero (hep-ph/0504025)

34. Limits on exclusive production (M.Gallinaro, 04.02.2005) KMRS  We are in the’ Higgs range’ (KMRS ~ 1pb) 5.3 KMR expectation : ϭjj(CEDP) ~ 1/ (ET min )

35. B. Cox, DIS-05 Exclusive dijets at Tevatron ExHuME Monte Carlo - direct implementation of KMR www.exhume-me.com J. Monk and A. Pilkington, hep-ph/0502077 Preliminary gg(Jz=0) qqg ,gggKRS will be implenented in ExHume MC Plot from B.C. and A. Pilkington, to be published

36. CDF Dijet production with 1&2 RGs K.Goulianos, DIS-05

37. KKMR-03

38. 47pb

39. Possible “standard candles” C,b

41. pp  p + γγ + p KMRS KMRS-04

42. events should be separated

43. CONCLUSION Forward Proton Taggingwouldsignificantlyextend the physics reachof the ATLAS and CMS detectors by giving access to a wide range of exciting new physics channels. For certain BSM scenarios the FPT may be the Higgs discovery channel within the first three years of low luminosity running  FPT may provide a sensitive window into CP-violation and new physics Nothing would happen unless theexperimentalists come FORWARDand do theREAL WORK We must work hard here – there is no easy solution

44. of Forward Proton Tagging 1. Thoushalt not worship any other god but the First Principles, and even if thoulikest it not, go by thyBook. 2. Thou slalt not make untotheeanygraven image, thou shalt not bow down thyself to them . {non-perturbative Pomeron and its MC implementations } 3.Thou shalttreat the existing diffractive experimental data in ways that show great consideration and respect. {HERA, CDF, D0} 4.Thou shalt drawthy daily guidance from the standard candleprocesses for testing thy theoretical models. 5. Thou shalt remember the speed of light to keep it holy. (trigger latency) 6.Thou shalt notdishonour backgrounds and shaltstudy them with great care. 7.Thou shalt notforget about the pile-up (an invention ofSatan). 8.Though shalt notexceed the trigger threshold and the L1 saturation limit. Otherwise thy god shall surely punish thee for thy arrogance. QCD

45. 9.Thou shalt not annoy machine people. 10. Thou shalt not delay, the LHC start-up is approaching

46. B.Cox, DIS05

47. Instrumenting the 420m region Diffracted protons emerge between beam pipes • Most likely scenario : Cryogenic bypass, warm beam pipes • First opportunity to replace 420m cryostat is in planned long shutdown after first physics runs of LHC (autumn 2008?) • UK FP420 is funded for R&D (including 3D silicon detector research) • Belgium FP420 is funded for R&D (detector mechanics and electronics) • Negotiations in progress for cryogenic engineer to design prototype 420m cryostat (in collaboration with AT-CRI group at CERN and UK Cockcroft Institute) • FP420 meeting at CERN May 30th - 31st. Video available. Aim for LOI to LHCC at end of June. All welcome (Contact Brian Cox / Albert De Roeck / Mike Albrow (US)) . • FP420 is not a ‘collaboration’. It is an R&D project which will hopefully lead to new sub-detectors for ATLAS and / or CMS.