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Diffractive Processes as a Tool to Study New Physics at the LHC

Diffractive Processes as a Tool to Study New Physics at the LHC. 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.

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Diffractive Processes as a Tool to Study New Physics at the LHC

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  1. Diffractive Processes as a Tool to Study New Physics at the LHC

  2. CMS & ATLASwere 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 p p RG

  3. R. Orava, ISMD-05 recall bj’s idea of FAD

  4. PLAN 1. Introduction (a gluonic Aladdin’s lamp) 2.Basicelements of KMR 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. Conclusion 6. Ten commandments of Physics with Forward Protons at the LHC .

  5. Forward Proton Taggersas a gluonicAladdin’s Lamp (Old and NewPhysics menu) • Higgs Hunting(the LHC ‘core business’)K(KMR)S- 97-04 • Photon-Photon, Photon - HadronPhysics • ‘Threshold Scan’:‘Light’ SUSY ...KMR-02 • Various aspects of DiffractivePhysics (soft & hard ).KMR-01 (strong interest from cosmic rays people) • LuminometryKMOR-01 • 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 to complement the conventionalstrategies at theLHCandILC. Higgs is only a part of a broad diffractiveprogram@LHC a wealth of QCD studies , photon-hadron interactions… FPT an additionalphysics menu in ILC@LHC

  6. RGsignature for Higgs hunting( Dokshitzer, Khoze, Troyan, 1987) Sudakov suppression Bialas-Landshoff- 91rescattering/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 (CDPE) ~ 10 * (incl) The basic ingredients of the KMR approach(1997-2005) Interplay between the soft and hard dynamics -4

  7. 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) How would you explain it to your (grand) children ? Forcing two (inflatable) camels to go through the eye of a needle H P High price to pay for such aclean environment: σ (CEDP) ~ 10 -4 P

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

  9. MAIN FEATURES ^ (GLM, M.Bloch et al, M. Strikman et al, V.Petrov et al.) ^ ^ -016 • 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) good agreement with all other groups andMC. • S²/b² - quite stable (within 10-15%) KMR(S) • 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 ^ 3.3 6 • Jz=0 ,even P-selection rule forσ is justified only if <pt>² /<Qt>² « 1

  10. Central Exclusive Production of a New Heavy State M We shouldn’t underestimate photon fusion !

  11. Higgs boson LHC cost REWARD 2.5 billion

  12. Current consensus on the LHC Higgs search prospects • 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 of MSSM, MSSM with CP-violation….. • More surprises may arise in other SUSY non-minimal extensions : NMSSM…. • After discovery stage(Higgs identification): Common strategy: The ambitious program of precise measurements of the H mass, width, couplings, and, especially of the quantum numbers and CP properties would require an interplay with a ILC

  13. 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/analyser. ( 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,especially at largetanβ (gg)CED  bb LO (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,MSSM, smalleff ‘benchmark’ MSSM scenario • New leverage –proton momentum correlations (probes of QCD dynamics, pseudoscalar ID, CP violation effects)KMR-02

  14. 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 :10 signal / O(10) background in 30 fb-1 (with detector cuts) (optimistic, but not inconceivable) WW* : MH = 120 GeV s = 0.4 fb MH = 140 GeV s = 1 fb MH = 140 GeV :5-6 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. • 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 • If we see SM-like Higgs + p- tags the quantum numbers are 0++ H H

  15. ☺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 low pt-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 ☻good prospectsto double the signal rate(triggerthresholds) ☻smalleff MSSM benchmark scenario – (factor of ~4)

  16. The MSSM and more exotic scenarios • NMSSM( with J. Gunion et al in progress) 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)

  17. (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

  18. The MSSM can be very proton tagging friendly suppressed enhanced 0++ selection rule suppresses A production: CEDP ‘filters out’ pseudoscalar production, leaving pure H sample for study 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 The intense coupling regime is where the masses of the 3 neutral Higgs bosons are close to each other and tan  is large MA = 130 GeV, tan = 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

  19. 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

  20. Helping to cover the LHC gap? 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 pile-up ?

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

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

  23. J. Ellis et al. hep-ph/0502251 Scenario with CP violation in the Higgs sector and tri-mixing “lineshape analysis”

  24. e.g. mA = 130 GeV, tan  = 50 L = 30 fb-1 S B mh = 124.4 GeV 71 ~ 3 events mH = 135.5 GeV 124 ~2 mA = 130 GeV 1 ~2 bb X M 1 GeV WW*/WW modes are looking extremely attractive.  mode looks quite promising 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

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

  26. H various potential problems of theFPTapproach reveal themselves however there is a (good) chance to observe such an invisible object, which, otherwise, may have to await aILC searches for extra dimension – diphoton production(KMR-02) • 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 directlyon L1 on the proton taggers • low luminosity : L= 10³² -10³³cm-2 sec-1 (pile-up problem) , • forward calorimeters(…ZDC) (QED radiation , soft DDD), • veto from the T1, T2- type detectors (background reduction, improving the trigger budget)

  27. 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, breaking news

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

  29. CDF-2000 KKMR-01 The measured CDF dijet diffractive distributioncomparedwith KKMR predictions

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

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

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

  33. pp  p + γγ + p KMRS-04

  34. KMRS-04

  35. BREAKING NEWS

  36. (KMR/ExHume)

  37. We (FP-420) must work hard here – there is no easy solution 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 before theexperimentalists come FORWARDand do theREAL WORK

  38. FP420 (68 authors, 29 institutes in 10 countries on both ATLAS and CMS) 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 From the LHCC minutes (October 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 programme and the interest in its exploring its feasibility.

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