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

☺ YES-> Forward Proton Tagging 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

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

(a gluonic Aladdin’s lamp) PLAN 1. Introduction (a gluonic Aladdin’s lamp) 2.Basic elements 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 .

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 ) Luminometry KMOR-01 High intensity Gluon Factory. KMR-00, KMR-01 QCD test reactions, dijet luminosity monitor Searches for new heavy gluophilic states KMR-02 FPT ☻ Would provide a unique additional tool to complement the conventional strategies at the LHC and ILC.  Higgs is only a part of a broad diffractive program@LHC a wealth of QCD studies , photon-hadron interactions… FPT  an additional physics menu in ILC@LHC

The basic ingredients of the KMR approach (1997-2005) Interplay between the soft and hard dynamics RG signature for Higgs hunting ( Dokshitzer, Khoze, Troyan, 1987) 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 -4 (CDPE) ~ 10 * (incl)

σ (CEDP) ~ 10 σ( inclus.) H P P W = S² T² -4 High price to pay for such a clean environment: σ (CEDP) ~ 10 -4 σ( inclus.) Rapidity Gaps should 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 P

(x’~Qt/√s) <<(x~ M/√s) <<1 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 ( the apparent divergency in the Qt integration nullifies) <Qt>SP~M/2exp(-1/αs), αs =Nc/π αs Cγ SM Higgs, <Qt>SP ≈ 2 GeV>> ΛQCD

An important role of subleading terms in fg(x,x’,Qt²,μ²), MAIN FEATURES An important role of subleading terms in fg(x,x’,Qt²,μ²), (SL –accuracy). Cross sections σ~ (fg ) ( PDF-democracy) S² KMR=0.026 (± 50%) SM Higgs at LHC (detailed two-channel eikonal analysis of soft pp data) good agreement with all other groups and MC. 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 ^ ^ (GLM, M.Bloch et al, M. Strikman et al, V.Petrov et al.) ^ ^ -016 3.3 6 Jz=0 ,even P- selection rule for σ is justified only if <pt>² /<Qt>² « 1

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

Higgs boson LHC cost REWARD 2.5 billion

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): 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

~4 GeV(currently feasible) Valuable quantum number filter/analyser. The advantages of CED Higgs production Prospects for high accuracy mass measurements ( ΓH and 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 Higgs CP at the LHC conventionally. (an important ingredient of pQCD approach, otherwise, large |Jz|=2 …effects, ~(pt/Qt)2 !) H ->bb, especially at large tanβ (gg)CED  bb LO (NLO,NNLO) BG’s -> studied SM Higgs S/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

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) H 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

☺ 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 prospects to double the signal rate (trigger thresholds) ☻ small eff MSSM benchmark scenario – (factor of ~4)

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 et al in progress)

MA ≤ 120-150GeV, tan β >>1 ( E.Boos et al,02-03) (a )The intense coupling regime MA ≤ 120-150GeV, tan β >>1 ( E.Boos et al,02-03) h,H,A- light, practically degenerate large Γ, 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 for CEDP: ☺ (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 filter A out

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 suppressed enhanced 0++ selection rule suppresses A production: CEDP ‘filters out’ pseudoscalar production, leaving pure H sample for study 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 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

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

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 ?

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

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

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

Summary of CEDP e.g. mA = 130 GeV, tan  = 50 L = 30 fb-1 S B 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  = 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

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

 searches for extra dimension – diphoton production (KMR-02) 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 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), veto 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)

Still more work to be done to constrain the uncertainties 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 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, breaking news

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

CDF-2000 KKMR-01 The measured CDF dijet diffractive distribution compared with KKMR predictions

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

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

CHIC DIS04 KMR-01, 70 pb 47 pb

pp  p + γγ + p KMRS-04

KMRS-04

BREAKING NEWS

(KMR/ExHume)

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. 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 the experimentalists come FORWARD and do the REAL WORK We (FP-420) must work hard here – there is no easy solution

FP420 LOI-submitted to the LHCC: CERN-LHCC-2005-025 LHCC-I-015 (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.