Forward Proton Tagging at the LHC as a Means to Search for New Physics

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Forward Proton Tagging at the LHC as a Means to
Search for 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
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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 dL 5)
• ? Lack of

p
p
RG
Is there a way out? ? YES-gt Forward Proton
Tagging Rapidity Gaps ? Hadron Free
Zones matching ? Mx dM (Missing Mass)
X
RG
p
p
talk by A. De Roeck
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• Forward Proton Taggers as a
  gluonic Aladdins 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 )
• High intensity Gluon Factory (underrated gluons)
  KMR-00, KMR-01
  
• QCD test reactions, dijet P-luminosity monitor
  
• Luminometry
  KMOR-01
• Searches for new heavy gluophilic states
  KMR-02, KMRS-04
• FPT
• ?Would provide a unique additional tool to
  complement the conventional strategies at
  the LHC and ILC.

FPT ? will open up an additional rich physics
menu ILC_at_LHC
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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). Developed and promoted by
Bjorken (1992-93)

• 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
• ltQtgt gtgt/\QCD in order to go by pQCD book

- 4
?(CDPE) 10 ? (incl)
5
Higgs boson
LHC cost
2.5 billion
REWARD
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• 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)
• ? 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

What about the H- quantum numbers and the Hbb
coupling ?
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• The advantages of CED Higgs production
• Prospects for high accuracy mass measurements
  irrespectively of the decay mode.
• ( H-width and even missing mass lineshape
  in some BSM scenarios).
• Valuable quantum number filter/analyzer.
• ( 0 dominance C , P-even)
• ? difficult or even impossible to explore the
  light Higgs CP at the LHC conventionally.
• (selection rule - an important
  ingredient of pQCD approach,
• H -gtbb readily available
• (gg)CED ? bb LO (NLO,NNLO) BGs -gt
  studied
• SM Higgs S/B3(1GeV/?M)
• complimentary information to the
  conventional studies.
• For some (troublesome) areas of the MSSM
  parameter space may become a discovery channel
• H ?WW/WW - an added value especially
  for SM Higgs with M 135GeV,
• ?? - an advantageous investment
• ? New run of the MSSM studies is underway
  (with G. Weiglein et al)

? LHC after discovery stage, Higgs ID
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• ?Experimental Advantages
• Measure the Higgs mass via the missing mass
  technique
• Mass measurements do not involve Higgs decay
  products
• Cleanness of the events in the central
  detectors.
• Experimental Challenges
• Tagging the leading protons
• Selection of exclusive events backgrounds
• Triggering at L1 in the LHC experiments.
• bb-mode requires special attention.
• Uncertainties in the theory
• (Unusually) large higher-order effects, model
  dependence of
• predictions (soft hadronic physics is involved
  after all)

There is still a lot to learn from present and
future Tevatron diffractive data (KKMRS-
friendly so far).
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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 70 signal
/ (3-10) background in 30 fb-1 MH 135 GeV
125 signal / (2-5) background in 30 fb-1 MA
130 GeV 3 signal / (2-5) 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
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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 lt 180 GeV)
• -coverage mainly in the large tan ? and low MA
  region,
• -further improvements (trigger efficiency.)
  needed in order to increase
• coverage

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• ? h,H? ?? in the low mass range (MAlt180 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-flow ETgt10-20 GeV) KKMR-04

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MSSM
V.A.Khoze, S.Heinemeyer, W.J.Stirling, M.Ryskin
M. Tesevsky and G. Weiglein in progress
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• 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
• Rate of CED high-Et dijets, observed yield of
  Central Inelastic dijets.
• (CDF Run I, Run II) data up to (Et)mingt50
  GeV, ( K.Terashis talk)
• 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 ??

BREAKING NEWS, CDF
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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 wide
• range of exciting new physics channels.
• ? FPT has the potential to make measurements
  which are unique at LHC and challenging even at
  a ILC.
• ?For certain BSM scenarios the FPT may be the
  Higgs discovery channel within the first three
  years of low luminosity running
• ? FPT offers a sensitive probe of the CP
  structure of the
• Higgs sector.
• Nothing would happen before the experimentalists
  engineers come FORWARD and do the REAL WORK .

• The RD studies must be completed within 12
  months
• (only limited time-scale and manpower
  available)

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FP-420
The LHC start-up is approaching
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FP420
(58 physicists from 29
institutes in 11 countries) Sub-detectors of
either or both of ATLAS CMS (common RD
route).


LOI-submitted to the LHCC CERN-LHCC-2005-025
LHCC-I-015 FP420 An RD Proposal to
Investigate the Feasibility of Installing Proton
Tagging Detectors in the 420m Region at LHC.
From the LHCC minutes (November 2005) The
LHCC heard a report from the FP420 referee. In
its Letter of Intent,the FP420 Collaboration puts
forward an RD 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 program
and the interest in its exploring its feasibility.
FP420 detector will replace the 420m
interconnection cryostat
First opportunity autumn 2008 (planned LHC
shutdown)