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Forward Proton Taggers in Diffractive Higgs Production

Explore extending Higgs physics reach at LHC with Forward Proton Taggers, discussing Standard Candles, and quantum number analyzing techniques.

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Forward Proton Taggers in Diffractive Higgs Production

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  1. Midterm Meeting, 11-13 October, 2004 Exclusive Diffractive Higgs Production and Related Processes V.A. Khoze (IPPP, Durham) & PNPI(St.Petersburg) In collaboration with A.B.Kaidalov, A.D.Martin ,M.G.Ryskin, W.J.Stirling • Main Aims: • to illustrate how the Higgs physics reach of the LHC can be significantly extended by addition • of Forward Proton Taggers. • to discuss the Standard Candles for testing • the theoretical predictions. • .

  2. CMS &ATLAS were designed and optimised to look beyond • the SM • -> High pt signatures in the central region • But… • Main physics ‘goes Forward’ • 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 • Photon –photon reactions we♥ILC p p RG Is there way out? ☺ YES-> Forward proton tagging Rapidity Gaps Hadron Free Zones Δ Mx ~δM (missing mass) X RG p p

  3. PLAN • 1. Introduction • (a gluonic Aladdin’s lamp) • 2. The key selling points of the Central • Exclusive Diffractive processes. • 3. Basic elements of the KMR approach • (a brief guide) • 4. Prospects for CED Higgs production. • the SM case • MSSM Higgses in the troublesome regions • MSSM with CP-violation • 5. Experimental checks (today and tomorrow) • 6. New recent development • 7. Conclusion

  4. Forward Proton Taggersas a gluonic • Aladdin’s Lamp • Rich Old and New Physics menu • Higgs Hunting (currently a key selling point). • Photon-Photon Physics. • ‘Light’ SUSY ( sparticle ‘threshold’ scan). • Various aspects of Diffractive Physics • (strong interest from cosmic rays people). • Luminometry. • High intensity Gluon Factory. • (lower lumi run, RG trigger…) • Searches for new heavy gluophilic states • (radions ,gluinonia,….), KK gravitons.. • Would provide a unique additional tool • to complement the conventional • strategies at theLHCandILC. • (a ‘ time machine’) • Not as ‘either the Higgs or nothing’

  5. The advantages of CED Higgs production • Prospects for high accuracy mass • measurements (ΓH in some MSSM cases) • mass windowM = 3 ~ 1 GeV (a wishlist) • ~4 GeV(currently feasible, Helsinki Group) • Valuable quantum number filter/analyser. • ( 0++dominance ;C,P-even) •  No obvious way toestablish theHiggsCP • at the LHC conventionally. • (an important ingredient of pQCD approach, • otherwise, large |Jz|=2 …effects, ~(pt/Qt)2!) • H ->bb ‘readily’ available • (gg)CED bb LO (NLO,NNLO) BG ->studied • SM HiggsS/B~3(1GeV/M) • complimentary information to the • conventional studies( also tau tau) • H->WW*,especially for SM Higgs with M≥ 135GeV • New leverage –proton momentum correlations • (probes of QCD dynamics, pseudoscalar ID, • CP violation effects.)

  6. The basic ingredients of the KMR approach(1997-2004) 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> >>/\QCD in order to go by pQCD book

  7. MIND THE GAP high price to pay for such a clean environment (CEDP) ~ 10-4(INCL) Rapidity Gaps should survive hostile hadronicRadiation Damages & ‘partonic pile-up’ W = S2 T2 • Colour charges of the ‘digluon dipoles’ are • screened only at r> 1/<Qt> • GAP KEEPERS(survival factors), • protecting RG against: • the debris of QCD radiation with M>kt>Qt(T) • soft rescattering effects (necessitated by unitarity) (S) Forcing two (inflatable) camels to go through the eye of a needle

  8. schematically skewed unintegrated structure functions (suPDF) (x’~Qt/√s) <<(x~ M/√s) <<1 (Rg=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) • Good agreement with other ‘unitariser’s approaches and MCs. • S²/b² - quite stable (within 10-15%) • S²~ s(Tevatron-LHC range) • dL/d(logM² ) ~ 1/ (16+ M) • 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

  10. 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

  11. SM Higgs, CEDP LHC, L=30fb-1 KMR-00,KKMR-03 M(GeV) 120 140comments accuracy σ 3fb 1.9fbcould be improved (1 -5.5fb)(0.6-3.5fb)(th. exp. CEDPdijets Mjj~M) Sbb11 3.5cuts +effi.s (S/B)bb3(1GeV/M) 2.4(1GeV/ M)cuts +effis. LO,NLO Bgd Sww* 3.68.4 LH,LL domin. . 6 (MC+det. sim) ADR & MSdetailed MC needed (S/B)ww* >>1 >>1detailed MC studies needed ZZ*+tau tau

  12. ‘Natural’ low limit - 0.1fb(photon fusion) • ☺An added value of the WW* • ‘less demanding’ experimentally • (trigger and mass resolut. requirements..) • high acceptances and efficiencies • an extension of well elaborated conventional program, • (existing experience, MC’s………) • (studied backgrounds: pure QED, gg->qqW, gg-WW*…) • Note in passing: • mass resolution is rising with M • prospects of accurate H mass measurements , • 0+ assignment ,spin-parity analyzing • - still hold

  13. 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) • The MSSM with explicit CP violation (A.Pilaftsis,98;M.Carena et al.,00-03,B.Cox et al 03)

  14. Higgs couplings (G.Weiglein)

  15. (a )The intense coupling regime • MA≤ 120-150GeV, tanbeta >>1( E.Boos et al,02-03) • h,H,A- light, practically degenerate • large wdths, must be accounted for • the ‘standard’ modes WW*,ZZ*, gamma gamma …- • strongly suppressed v.s. SM • the best bet –mu mu channel, • In the same time – especially advantageous for CEDP: ☺ • (KKMR 03-04) • σ(Higgs->gg)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 beta < 5-10 • (the LHC wedge, windows) • (c) The decoupling regime • (in reality, MA>140 GeV, tan beta >10) • h is SM-like, H/A -heavy and approximately degenerate, • CEDP may allow to filter Aout ~ ~

  16. The intense coupling regime of the MSSM The intense coupling regime is where the masses of the 3 neutral Higgs bosons are close to each other and tan b is large suppressed enhanced 0++ selection rule suppresses A production: CEDP ‘filters out’ pseudoscalar production, leaving pure H sample for study for 5 s with300 (30) fb-1

  17. decoupling regime: mA ~ mH large h = SM intense coup: mh ~ mA ~ mH ,WW.. coup. suppressed • with CEDP: • h,H may be • clearlydistinguishable • outside130+-5 • GeV range, • h,H widths are quite different

  18. 5signal at LHC 30 fb-1 300 fb-1

  19. SMpp  p + (Hbb) + p S/B~11/4(M) with M (GeV) at LHC with 30 fb-1 e.g. mA = 130 GeV, tan  = 50 (difficult for conventional detection, but CEDP favourable) S B mh = 124.4 GeV 71 3 mH = 135.5 GeV 124 2 mA = 130 GeV 1 2 X M 1 GeV incredible significance(10 s.d.) for Higgs signal even at 30 fb -1

  20. The intermediate regime. The ‘LHC window’. With CEDP the mass range up to 160-170 GeV can be covered at 300 fb-1

  21. pp->p+H+p Higgs An additional valuable tool A(0-), CPX More IR-sensitive

  22. more peripheral p1T,p2T correlations reflect spin-parity of central system: can distinguish 0- from 0+ pp->p1+H+p2

  23. Probing CP violation in the Higgs Sector A ‘CPX’ scenario KMR-04 CP even

  24. 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 scenario • 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

  25. 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) • ‘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 • The HERA data on diffractive high Et dijets in • Photoproduction. • (Klasen& Kramer-04 NLO analysis) • Preliminary CDF results on exclusive charmonium • CEDP. Higher statistics is on the way. • Energy dependence of the RG survival (D0, CDF) • (…..in the time of writing has still survived theexclusion limits • set by the Tevatron data…. (M.Gallinaro, hep-ph/01410232)

  26. KMR-00 CEDP ~ 1 nb KMR-04 ~40pb ‘OPTIMISTIC ‘ models ruled out experimentally (Run I-published , Run II, prelim) More tests with upcoming Tevatron run-II data

  27. Test of factorization understood in terms of rescattering corrections

  28. CDF-00 KKMR-01 The measured CDF dijet diffractive distributioncomparedwith KKMR predictions

  29. Soft survival factors for RG no inelastic interaction.

  30. Diffractive dijet production ,Tevatron KKMR-03 KMR-00, prediction A.Bialas& R.Pecshanski 03 2 K.Goulianos 2 2 2 2

  31. Possible “standard candles” C,b

  32. Diffractive  production KMR+Stirling (KMR-01,KMRS-04) also Petrov &R.Ryutin-04 only (order-of-magnitude) estimates possible forcharmonium production

  33. KMR-01, 70 pb

  34. KMRS - 04 KMRS

  35. “Standard Candles” at Tevatron to test excl. prod. mechanism ppp +  + p high rate, but low scale (uncertainties in the estimates) ppp + jj + p rate rather high, but exclusive peak may be washed out ppp + + p low rate, but cleaner signal

  36. Some recent development • …Fromthe myth about the‘wide range of predictions • to the realities of calculations… • Sensitivity studies of the uPDFs to the details ofthegluon kt-distribution • (L.Lonnblad & M.Sjodalh,03 ,H.Jung) • The bottom line: currently - mainly • kt- integrated gluon densities are tested. • The PYTHIA MC result for the soft • Gap Survival factor (LHC)=0.026. • (L.Lonnblad, March 04 ) DKS-1992 • bj, KKMR, GLM, M.Strikman et al -analytical results • Correlations between the proton pt’s - a way to probe the dynamics of diffraction (unitarity effects) and the properties • of the central system • (K(KMR) 02-04; A. Kupco et al 04; • V.Petrov et al, 04). • A (simple) model for CEDP with gluon • uPDF fitted to HERA elastic data. • (DL Sudakov and unitarization included) • (V.Petrov & R.Ryutin,04)

  37. MC and detector simulation studies • (Manchester, Saclay groups, V.Petrov et al). • Studies of the possibility to observe • an ‘Invisible Higgs‘ • (KMR, 04) • Even more severe background and • trigger conditions • Fashion takes its toll • gluinonia in split SUSY scenarios • (Durham group…) depends on survival

  38. HERA Experiments: (what we would like to have for Xmas) Thanks to Aliosha, Leif, Michael and Misha main aim: to constrain un(integrated)gluonatHERA • Reanalyze dijets in photoproduction at higher ET. • Measure ratios of diffractive/inclusive crosssectionsat HERA at high ET(KMR-03)  Photon PDF uncertainties cancel  Hadronization corrections cancel • Measure FL atx=0.005-0.03, Q2=3-30GeV2 • Exclusive charmonium production (possiblehandleon the suPDF) • Inclusive photoproduction of high Et (~20-40GeV) jets in the current fragmentation region (pt-distribution)

  39. CONCLUSION CONCLUSION • Forward Proton Tagging proves to be • a promisingvaluable tool to study the Higgs • physics at the LHC. • Exclusive Diffractive Higgs Production may • provide a unique possibility to cover the • troublesome domains of the MSSM and to • verify the identity of the Higgs-like candidates. • So far Durham approach has • survived the experimental tests. • The predicted rates for New Physics • signals can be checked experimentally by theproposedStandardCandle processes. • …still a lot of studies to be done…. • FORWARD PHYSICS NEEDS FORWARD • DETECTORS • Nothing would happen unless • the experimentalists come FORWARD and do • REAL WORK

  40. Summary and work in progress • If you see a resonance with proton tags, you know its quantum numbers • Proton tagging allows excellent mass resolution • If the Higgs (or any other new particles) couple strongly to gluons, proton tagging may be the discovery channel • Proton tagging allows access to bb decay modes if good enough detector resolution can be achieved • The Monte Carlo tools are coming on stream • The detectors can be warm at 420m - cryostat redesign is cheap • It is still desirable (and possible?) to trigger directly at level 1 on 420m pots (at least at CMS) - work in progress • Central bb trigger strategies including 220m asymmetric options) under study • We (UK groups) are bidding to begin serious R&D by mid 2005

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