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Forward Proton Tagging at the LHC as a Tool to Study New Physics

Forward Proton Tagging at the LHC as a Tool to Study New Physics. V.A. K hoze (IPPP, Durham). main aims  to illustrate the theoretical motivations behind the recent proposals to add the F orward P roton T aggers to the LHC experiments.

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Forward Proton Tagging at the LHC as a Tool to Study New Physics

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  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. PLAN • 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) • Conclusion • 7. Ten commandments of Physics with • Forward Protons at the LHC • .

  3. 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 • (luminositygoal ofδL ≤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 p p RG Is there a way out? ☺YES-> Forward Proton Tagging Rapidity Gaps  Hadron Free Zones matchingΔ Mx ~δM (Missing Mass) X RG p p talk by A. De Roeck

  4. 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) • High intensityGluon Factory(underrated gluons)KMR-00, KMR-01 • QCD test reactions, dijet P-luminosity monitor • Luminometry KMOR-01 • Searches for new heavy gluophilic statesKMR-02, KMRS-04 • FPT • Would provide a unique additional tool to complement the conventionalstrategies at theLHCandILC. Higgs is only a part of the broad EW, BSM and diffractiveprogram@LHC • wealth of QCD studies, glue-glue collider, photon-hadron, photon-photon interactions… FPT  will open upan additional richphysics menu ILC@LHC Albert De Roeck

  5. The basic ingredients of the KMR approach (Khoze-Martin-Ryskin 1997-2006) Interplay between the soft and hard dynamics RGsignature for Higgs hunting(Dokshitzer, Khoze, Troyan, 1987). Developed and promoted by Bjorken (1992-93) • 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 - 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 a clean environment: σ (CEDP) ~ 10 -4 σ( inclus.) Rapidity Gapsshould survive hostilehadronicradiation damagesand ‘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 P

  8. Reliability of predn of s(pp p + H + p) crucial contain Sudakov factor Tg which exponentially suppresses infrared Qt region  pQCD H S2 is the prob. that the rapidity gaps survive population by secondary hadrons  soft physics  S2=0.026 (LHC) S2=0.05 (Tevatron) s(pp  p + H + p) ~ 3 fb at LHC for SM 120 GeV Higgs ~0.2 fb at Tevatron

  9. 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.

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

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

  12. Higgs boson LHC cost 2.5 billion REWARD

  13. 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 troublesomeareas 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(HiggsIdentification): • 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

  14. The advantages of CED Higgs production • Prospects for high accuracy mass measurements irrespectively of the decay mode. • (H-widthand evenmissing masslineshape in some BSM scenarios). • Valuable quantum number filter/analyzer. • ( 0++dominance ;C , P-even) • difficult or even impossible to explore thelight HiggsCPat theLHCconventionally. • (selection rule - an important ingredient of pQCD approach, • H ->bb ‘readily’ available • (gg)CED bbLO (NLO,NNLO) BG’s -> studied • SM HiggsS/B~3(1GeV/M) • complimentary information to the conventional studies. • For some (troublesome)areas of the MSSM parameter space may becomea discovery channel • H→WW*/WW - an added valueespecially 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……

  15. ☻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 Albert De Roeck There is still a lot to learn from present and future Tevatron diffractive data (KMRS- friendly so far).

  16. 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) optimistically 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 H (with detector cuts) • 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) • TheWW 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++ H

  17. 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 )

  18. Theoretical Input

  19. (h  SM-like, H/A- degenerate.)

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

  21. 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 Well known difficult region for conventional channels, tagged proton channel may well be thediscovery channel,and is certainly a powerful spin/parity filter

  22. decoupling regime mA ~ mH150GeV, tan >10; 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

  23. 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 ?

  24. Ongoing studies (together with S. Heinemeyer, M.Ryskin, W..J. Stirling, M.Tasevsky and G. Weiglein) • ● Hbb in the high mass range(MA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(MA < 180 GeV) • -coverage mainly in the large tan  and low MA region, • -further improvements (trigger efficiency….) needed in order to increase • coverage • -

  25. PRELIMINARY hbb mhmax scenario, =200 GeV, MSUSY =1000 GeV

  26. Hbb PRELIMINARY

  27. ● h,H  in the low mass range (MA<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-flowET>10-20 GeV)KKMR-04 • pp p + X +A +Y +p • At the moment thesituation looks borderline

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

  29. Current understanding of the bb backgrounds for CED production for reference purposes SM (120 GeV)Higgsinterms 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

  30. 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):SH~1/M³ Bkgd :ΔM/Mfor , ΔM/Mfor  ( ΔM ,triggering, tagging etc improving with rising M) 6 8

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

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

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

  34. 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 - 0 + 0 KKMR -03

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

  36. Hunting the CP-odd boson, A

  37. Hunting the CP-odd boson, A (LO)selection rule – an attractive feature of the CEDPprocesses, 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-flowET>10-20 GeV)KKMR-04 pp p + X +H/A +Y +p(CDD) in LO azim. angular dependence: cos² (H), sin² (A), bkgd- flat A testing ground for CP-violation studies in the CDD processes (KMR-04) challenges: bb mode – bkgd conditions -mode- small (QED)bkgd, but low Br

  38. CDD results at  (RG) >3, ET>20 GeV 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, mg =10³GeV max

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

  40. Proton Dissociative Production(experimental issues) thanks to Monika, Michele & Albert Can we discriminate between the cos² and sin² experimentally ?  Measurement of the proton diss. system with ET 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 )? From both the theoretical and experimental perspectives the situation with searches for theAin diffractive processes looks at bestborderline, but the full simulation should be performed before arriving at a definite conclusion.

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

  42. an ‘Invisible ‘ Higgs KMR-04 H • 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) 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)

  43. 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 normalizationand the shapeof thedistribution) • 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 ofγγ • (in line with the KMRS calculations) BREAKING NEWS, CDF

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

  45. 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 well

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