H

1
Bialas Landshoff model revisited
Yesterdays orthodoxy is todays heresy
Brian
Moore
Phys.Lett. B256(1991) 540
H

• Pioneering work generated much further activity
• Based on the non-PT treatment of the lowest-order
  diagrams.
• Extended by Bialas et al (92-94) to predict
  di-jet production.
• Computation on the basis of the pure forward
  direction.
• .Thus our calculation really is an inclusive
  one
• (that is, it is NOT an exclusive result )
• Recently strong efforts to resurrect this
  approach taking it
• literally (Saclays group..)

2

• ? No quantitative predictive power
• strong IR sensitivity
• ?dQ²t/Q t 1/µ²
• uncontrollable higher-order radiative corrections
• as(µ²) log²(M²/µ²) as(µ²)log (s/µ²)
• ? Exclusiveness requires Gap Keepers
• (soft rescattering survival factor Sudakov
  form-factor)
• Otherwise-gt 2-3 orders of magnitude overshooting
• ? Can these be by-passed ?
• (e.g. by renormalizing using the observed rate of
  Central Inelastic

4
3

• ?Can these approach be used to predict hard
  semi-inclusive
• cross sections, such as for Central Inelastic
  Processes ?
• in principle,
• but sometimes and with a special care, in a
  certain kinematics,
• Central Inelastic Higgs/gg production
  
• 
  KMR-02, A.Bzdak-04

4

• ?Can these approach be used to predict hard
  semi-inclusive
• cross sections, such as for Central Inelastic
  Processes ?
• in principle,
• but sometimes and with a special care, in a
  certain kinematics,
• Central Inelastic Higgs/gg production
  
• 
  KMR-02, A.Bzdak-04

5
?The cross sections ?The mass/energy dependence
of the cross sections
a price to pay for model democracy /blindness
All recent publications now converge to a cross
section of 2-10 fb for a SM Higgs at the LHC
KMR, V.Petrov wt al, L.Lonnblad,M.Sjodahl

J. Forshaw
M.Boonekamp et al. repaired BL
QCD emission congestion (Sudakov-effect)
charging
KMR
Tevatron can probe the models
We cannot simply scale down the results by
dividing by the overshoot factor
6
Bialas Landshoff model revisited
Phys.Lett. B256(1991) 540
H

• Pioneering work generated much further activity
• Based on the non-PT treatment of the lowest-order
  diagrams.
• Extended by Bialas et al (92-94) to predict
  di-jet production.
• Computation on the basis of the pure forward
  direction.
• .Thus our calculation really is an inclusive
  one
• (that is, it is NOT an exclusive result )
• Recently several attempts to resurrect this
  approach
• 
  (Saclays group..)

7

• ? No quantitative predictive power
• strong IR sensitivity
• ?dQ²t/Q t 1/µ²
• uncontrollable higher-order radiative corrections
• as(µ²) log²(M²/µ²) as(µ²)log s/µ²)
• ? Exclusiveness requires Gap Keepers
• (soft rescattering survival factor Sudakov
  form-factor)
• Otherwise-gt 2-3 orders of magnitude overshooting
• ? Can these be by-passed ?
• (e.g. by renormalizing using the observed rate of
  Central Inelastic

4
8

• ?Can these approach be used to predict the
  semiinclusive
• cross sections, such as Central Inelastic
  Processes ?
• sometimes and with a special care
• for example, Central Inelastic Higgs/gg
  production KMR-02
• ? cannot be used to predict quark dijet
  production
• NLO,NLLO QCD effects, including radiation off the
  screening gluon
• should be taken into account
  DKMOR-02,KMR-02
• forward exclusive amplitude is irrelevant

9
High price to pay for such a clean
environment s (CEDP) 10
-4
s( INCL)
J.Forshaw
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)

Forcing two (inflatable) camels to go through the
eye of a needle
H
P
P
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pp-gtp M p MAIN FEATURES

sL(M²,y) s(M²)

• An important role of subleading terms (SL
  accuracy)
• Cross sections s (fg ) (
  PDF-democracy)
• S² KMR0.026 ( 50)
  SM Higgs at LHC
• Good agreement with other unitarisers
  approaches and MCs.
• S²/b² - quite stable (within 10-15)
• S² s
  (Tevatron-LHC range)
• dL/d(logM² ) 1/ (16 M)
• sH 1/M³ , (sB) ch ? M/ M , S/B M³/? M
  at M100GeV
• (S/B)bbM/?M at M
  lt100 GeV

4




-016
3.3
6
5

• Mass range 120-160 GeV ?- most CDEP -friendly

• Jz0 ,even P- selection rule for s is justified
  only if ltptgt² /ltQtgt² 1

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SM Higgs, CEDP LHC, L30fb-1 KMR-00,KKMR-03
M(GeV) 120 140
comments
accuracy s
3fb 1.9fb could be
improved (1 -5.5fb) (0.6 -3.5fb)
( th. exp.
CEDP dijets MjjM)
Sbb 11 3.5
cuts effi.s
(S/B)bb 3(1GeV/?M) 2.4(1GeV/ ?M) cuts
effis.
LO,NLO Bgd
Sww 3.6 8.4
LH,LL domin. .
6 (MCdet. sim)
ADR et al detailed MC needed
(S/B)ww gtgt1 gtgt1
detailed MC studies

needed ZZ ??
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The intense coupling regime of the MSSM
KKMR-03
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 with 300 (30) fb-1
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• ? 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
• two modes (bb and WW ) in the same experiment
• an extension of well elaborated conventional
  program,
• (existing experience, MCs)
• (studied backgrounds pure QED, gg-gtqqW, gg-WW)
  
• Note in passing
• mass resolution is rising with M

A. De Roeck et al
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5??signal at LHC
30 fb-1
300 fb-1
M
h/H/A
15
H?WW
H?bb
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CPX MSSM Higgs (KMR-03)
0 Selection rule
Also, since resolution of taggers gt Higgs width
QCD Background
But tt mode has only QED background
B.C., Forshaw, Lee, Monk and Pilaftsis
hep-ph/0303206 Khoze, Martin and Ryskin
hep-ph/0401078
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Factorization breaking in diffractivedijet
photoproduction
Resolved photoproduction
Direct photoproduction
? Factorization breaking
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Two-Channel Eikonal Model

• Hadronic collisions

• Photoproduction

Generalized vector meson dominance
Survival probability
Survival probability R ? S2 ? 0.34
KMR 00, KKMR 01
KKMR-03
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Soft survival factors for RG
no inelastic interaction.
20

• 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)
  K.Goulianos, K.Terashi
• 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
  K.Goulianos

21

• 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)
  K.Goulianos, K.Terashi
• 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
  K.Goulianos

22
C,b
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• Some recent development
• From the myth about the wide range of
  predictions
• to the realities of calculations
• Sensitivity studies of the uPDFs to the details
  of the gluon 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 pts - 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).

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• 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
26
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 RD
  by mid 2005

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CONCLUSION
CONCLUSION

• Forward Proton Tagging proves to be
• a promising valuable 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 the
  proposed Standard Candle processes.
• still a lot of studies to be done.
• FORWARD PHYSICS NEEDS FORWARD
• DETECTORS

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Central Exclusive Production
? One of the exciting possibilities Central
exclusive production of new massive states
(Higgs) Generates a large interest in the
CMS/ATLAS communities
R
? 7 UK groups submitted a proposal to PPARC for
RD for the 400m option
Extending the reach of the central detectors
Cryo-engineer,
detectors, trigger hardware, of order 2?106
? Has received go ahead
and now a PPRP bid is called for (early 2005)
29
A Forward view on Forward Physics at the LHC
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 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.
• .

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CDF2LHC

• TOPIC
  STATUS
• (Q2, t) dependence of DSF close to ready
• Exclusive cc production close to ready
• Low mass states in DPE need good trigger
• Exclusive b-bbar production in DPE need
  b-trigger
• x -dependence of DSF need low lum run
• Jet-gap-Jet w/jets in miniplugs need low lum run

K.Goulianos, Tev-4LHC_at_BNL 3-5 Feb 2005
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New FDJJ(b) from ZEUS-LPS Data
K.Goulianos,Tev-4LHC_at_BNL,3-5 Feb.2005
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Tevatron vs HERAFactorization Breakdown
(K.G0ulianos, PLB 358 (1995) 379)
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Summary

• Diffractive Higgs_at_LHC studies under way
• Both exclusive, inclusive, and also in single
  pomeron exchange
• Main issues for exclusive channel
• Cross section fb, but some die-hards believe it
  could be still larger
• Calculations seem to start converging, but still
  differences
• Tevatron will be the referee DPE ?c, ?b, ? ?,
  dijet production
• New detectors needed at 400 m (mechanics, 3D
  silicon detectors?)
• Optimize acceptance of the detectors, mass
  resolution (alignment?)
• L1 trigger 400m RP signals are too late for L1
  (ATLAS/CMS)
• Background from inclusive and exclusive channels.
  Generators in place. Isolate exclusive events.
• Study of other signals apart from bb (??, WW in
  progress)
• Note
• Higgs is only part of a broad diffractive program
  _at_ LHC
• Adding such detectors to LHC is NOT a walk in the
  park
• Tevatron (HERA) RP experience at this stage of
  the project is vital!

34
Cryostat upgrades
Very positive discussions with the machine group
Possible to modify the cryostat in
future! Two sections in cold but the
detectors warm Could be exchanged during a
shutdown Earliest autumn 2008
UK Project submitted to PPARC for cryostat and
detector RD
35
Problems with bb channel

• Trigger
• 420 m signals are too late for the L1 trigger
• The L1 trigger threshold in CMS for the jets is
  180 GeV
• Even with topological tricks still a factor of
  10 is missing in rate (see studies from
  Helsinki, Wisconsin, Bristol)
• Not final, but certainly not going to be easy
• Note rate determination contains a safety factor
  of 3-6
• Probably ok for asymmetric events, ie. 1 proton
  tagged in the 220m Roman Pot dijet trigger
  needs testing.
• However these events have a bad mass resolution
  measured in the pp system (1 ?6)
• Background
• QCD process gg?bb(g), even when bb production
  suppressed at LO, gg?qq(g) with
  misidentification
• S/B1 at best, likely lt1 (detector simulation)
• Detection efficiency of the bb
• Need to identify b-quarks/loose typically factor
  of 2
• ? Are the other usable channels

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