1 Exclusive Diffractive Higgs production and Related Processes (the key selling points for forward proton tagging at the LHC) To discuss the Standard.

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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

6 May 2005

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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

Is there a way out?

☺ YES-> Forward Proton Tagging

Rapidity Gaps Hadron Free Zones

Δ Mx ~ δM (Missing Mass)

RG

RG

X

pp

pp

p

M. Albrow, A.Rostovtsev -00

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PLAN1. Introduction

(a gluonic Aladdin’s lamp)

2.Basic elements 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

4. Exotics

5. Experimental checks

6. Conclusion

6. Ten commandments of Physics withForward Protons at the LHC

.

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Forward Proton Taggers as a gluonic Aladdin’s Lamp

(rich Old and New Physics menu)

•Higgs Hunting (the LHC ‘core business’) K(KMR)S- 97-04

•Photon-Photon, Photon - Hadron Physics

J.Ohnemus ,T.Walsh , P.Zerwas-93 ,KMR-02, K.Piotrzkowski

• ‘Threshold Scan’: ‘Light’ SUSY , tt... KMR-02 •Various aspects of Diffractive Physics (soft & hard ). KMR-01

(strong interest from cosmic rays people )

•Luminometry KMOR-01 , K.Piotrzkowski

•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 tc complement the conventional strategies at the LHC and ILC.

Higgs is only a part of a broad diffractive program@LHC

FPT an additional physics menu in ILC@LHC

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The basic ingredients of the KMR approach (1997-2005)

Interplay between the soft and hard dynamics

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

Sudakovsuppression

(A. Berera & J.Collins-96 )

(CDPE) ~ 10 * (incl)-4

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(CDPE) ~ 10 * incl-4

How would you explain it to your (grand) children ?

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Forcing two (inflatable) camels to go through the eye of a needle

High price to pay for such a clean environment:

σ (CEDP) ~ 10 -4

σ( inclus.)

Rapidity Gaps should survive hostile hadronic radiationdamages and ‘partonic pile-up ‘

W = S² T²Colour 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)

HP P

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skewed unintegrated structure functions (suPDF)

schematically

(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

(x’~Qt/√s) <<(x~ M/√s) <<1

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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)

surprisingly good agreement with other ‘unitarizer’s approaches and MCs.

• 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

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-016

3.3

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• Jz=0 ,even P- selection rule for σ is justified only if <pt>² /<Qt>² « 1

^

^

^

(J. Pumplin-95)

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pp ‘New Heavy’ States M

(S²)γγ =0.86 (KMR-02) αs²/8

we should not underestimate photon fusion ! .

T²

²

QCD-’radiation damages’

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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/analyzer.

( 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 ‘readily’ available

(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 valueespecially for SM Higgs with M≥ 135GeV, MSSM at l ow tanβ

• New leverage –proton momentum correlations (probes of QCD dynamics, pseudoscalar ID,

CP violation effects) KMR-02

(Helsinki group)

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☻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

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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 MSSM h-boson most probably cannot ☺escape detection ,and in large areasof 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 SUSYnon-minimal extensions

• After discovery stage (Higgs identification):

The ambitious program of precise measurements of the mass, width, couplings,and, especially of the quantum numbers andCP properties would require an interplay with a ILC

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SM Higgs Cross Section * BR

Cross sections ~O(fb)

Diffractive Higgs mainly studied for Hbb -K(KMR)97-04-DKMOR-02

Boonekamp et al. ,01-04 SM Higgs

Petrov et al. ,04

Recently study extendedfor the decay into WW*,WWcan reach higher masses

‘Leptonic trigger cocktail’ (WW,bb,ZZ,)

FT420 UK team

Note, Hbb (120 GeV) at Tevatron 0.13 fb

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H

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

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

•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++

Exclusive SM Higgs production

(with detector cuts)

(with detector cuts)

H

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☺ An added value of the WW channel

1. ‘less demanding’ experimentally(trigger and mass resolution requirements..)

allows to avoid the potentially difficult issue of triggeringon 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 forby 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

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The Benchmark process : SM Higgs production

B.C., A. De Roeck, V. A. Khoze,,W. J. Stirling et. al. To be published

B. Cox, DIS-05

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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)

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(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 ~

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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 studyMA = 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

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 MSSM can be very proton tagging friendly

for 5 ϭ BR(bb) > 0.7fb (2.7fb) for 300 (30fb-1)

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decouplingregime:mA ~ mH largeh = SM

intense coupl:mh ~ mA ~ mH

,WW.. couplsuppressedwith CEDP:•h,H may beclearly distinguishableoutside130+-5 GeV range, •h,H widths are quite different

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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

Helping to cover the LHC gap?

Needs ,however, still full simulation

needs update

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Spin Parity Analysis

• Azimuthal angle between the leaprotons depends on spin of H

• Measure the azimuthal angle of the proton on the proton taggers

Azimuthal angle between the leading protons depends on spin of H

angle between protons angle between protons with

rescattering effects included

KKMR -03

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CP even

CP odd active at non-zero t

Azimuthal asymmetry in tagged protons provides direct evidence for CP violation in Higgs sector

Probing CP violation in the Higgs Sector

‘CPX’ scenario (in fb)

KMR-04

A is practically uPDF - independent

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In the tri-mixing scenario we expect ϭ bb ~ 1fb and proton asymmetries A ~0.1-03

tan β=50, MH+=150 GeV

CP- violating MSSM with large tri-mixing J.Ellis et al 05

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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 = 50(difficult for conventional detection,but exclusive diffractive favourable)

L = 30 fb-1

S Bmh = 124.4 GeV 71 3 eventsmH = 135.5 GeV 124 2

mA = 130 GeV 1 2

X M 1 GeV

WW*/WW modes are looking extremely attractive.

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…the LHC as a ‘gluino factory’ , N. Arkani-Hamed ( Pheno-05)

BFK-92

KMR-02

pp pp + ‘nothing’ (215 m ?)

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an ‘Invisible ‘ Higgs KMR-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 directly on L1 on the proton taggers

•low luminosity : L= 10 ³² -10 ³³ cm -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)

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EXPERIMENTAL CHECKS

•Up to now the diffractive production data are consistent with K(KMR)S resultsStill more work to be done to constrainthe uncertainties

•Very low rate of CED high-Et dijets ,observed yieldof Central Inelastic dijets. (CDF, Run I, Run II) data up to (Et)min>50 GeV

• ‘Factorization breaking’ between the effective diffractive structure functions measuredat 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 oneand two rapidity gaps

• Preliminary CDF results on exclusive charmoniumCEDP. Higher statistics is underway.

•Energy dependence of the RG survival (D0, CDF)• CDP of γγ, data are underway

KKMR .….. has still survived the exclusion limitsset by the Tevatron data…. (M.Gallinaro, hep-ph/01410232)

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Tevatron vs HERA:Factorization Breakdown

dN/dgapdN/d

gap

p

ppIP

CDF

H1

p

ppIP

e*

tp

IP

(K.G0ulianos, PLB 358 (1995) 379)

p

well

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Exclusive Dijets in Run I

KMR-00 )

e+e- -> jj with similar jet selection

rejection of ‘optimistic’ theoretical models

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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)

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(M.Gallinaro, 04.02.2005)

(KMRS ~ 1pb)

KMR expectation : ϭjj(CEDP) ~ 1/ (ET min )5.3

Limits on exclusive production

KMRS

We are in the’ Higgs range’

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Exclusive dijets at Tevatron

ExHuME Monte Carlo - direct implementation of KMR

www.exhume-me.com

J. Monk and A. Pilkington, hep-ph/0502077

Plot from B.C. and A. Pilkington, to be published

B. Cox, DIS-05

gg(Jz=0) qqg ,ggg KRSwill be implenented in ExHume MC

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K.Goulianos, DIS-05

Dijet production with 1&2 RGsCDF

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KKMR-03

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47pb

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Possible “standard candles”

C,b

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KMRS

pp p + γγ + p

KMRS-04

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events should be separated

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CONCLUSION

Forward Proton Tagging would significantly extend the physics reach of the ATLAS

and CMS detectors by giving access to a widerange 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 intoCP-violation and new physics

Nothing would happen unless the experimentalists come FORWARD and do the REAL WORK

We must work hard here – there is no easy solution

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of Forward Proton Tagging

1. Thou shalt not worship any other god but the First Principles,and even if thou likest it not, go by thy Book.

2. Thou slalt not make unto thee any graven image,thou shalt not bow down thyself to them . {non-perturbative Pomeron and its MC implementations }

3.Thou shalt treat the existing diffractive experimental data in ways that show great consideration and respect. {HERA, CDF, D0}

4. Thou shalt draw thy daily guidance from the standardcandle processes for testing thy theoretical models.

5. Thou shalt remember the speed of light to keep it holy. (trigger latency)

6.Thou shalt not dishonour backgrounds and shalt study them with great care.

7.Thou shalt not forget about the pile-up (an invention of Satan).

8. Though shalt not exceed the trigger threshold andthe L1 saturation limit. Otherwise thy god shall surely punish thee for thy arrogance.

QCD

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9. Thou shalt not annoy machine people.

10. Thou shalt not delay, the LHC start-up is approaching

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B.Cox, DIS05

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Instrumenting the 420m region

• 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?)

Diffracted protons emerge between beam pipes

• 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.