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Diffractive processes as a means to study new physics at the LHC

VAK, ADM, WJS and G.W.,visit. profs: A.De Roeck, A.Kaidalov, M.Ryskin + 6 young int. scientists + FP-420 team membs

Main aims: the theoretical motivations behind the recent proposals to add the Forward Proton taggers to the LHC experiments.

the basic ingredients of Durham approach through the eyes of existing Tevatron and HERA diffractive data.

direct engagement with experimentalists in analysing and planning the forward measurements, in part., FP420 R&D.

Theor. challenges :● need for the elaborated and well tested models for soft diffraction. ●unusually & uncomfortably large higher-order QCD eff. (e. g. Sud. and non-Sud. Logs… ). ● no suitable conventional analytic or MC results readily available (colour singl., Jz=0) .

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Topics addressed so far (25 published papers)

• Higgs Hunting in the proton tagging mode. KKMRS- 00-06

• Various aspects of Diffractive Physics (soft & hard ) at the LHC. KKMR - 00-

01,05,06 • High intensity Gluon Factory at hadron colliders . KMR -

00,01,02

• proton-proton luminometry at the LHC. KMOR-01

• photon-photon, photon - hadron physics at the LHC. KMR-02

• WBF mechanism of Higgs production with Rap. Gaps . DKMRO-02, KRSW-03

• Studies of the QCD & EW backgrounds to the H-> bb, WW signals. DKMOR-02, KRS-05,

CDKNPRST-05 • Central Exclusive Diffractive Production as a CP-parity analyser. KKMR-03,

KMR-04. • ‘ Threshold Scan’ in the CEDP processes. KMR-02

• Exotics in the CEDP processes (‘invis’. Higgs, extra dim…) KMR-02, BKMR-04

• ‘ Standard candle’ processes at the Tevatron to test theor. predictions KKMRS -01-05

• Tests of models for diffraction at HERA . KKMR -01,03,06.

• Diffraction of nuclei at high energies KKMR-03

FP tagging would provide a unique additional tool to complement the conventional strategies at the LHC and ILC.

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The main advantages of CED Higgs production

• Prospects for high accuracy mass measurements (irrespectively of the decay mode).

• Quantum number filter/analyser. ( 0++ dominance ;C,P-even)

• H ->bb opens up (Hbb- coupl.)

(gg)CED bb in LO ; NLO,NNLO, b- mass effects - controllable.

• For some areas of the MSSM param. space CEDP may become a discovery

channel !• H →WW*/WW () - an added value ( Less challenging experimentally + small bgds.)

• New run of the MSSM studies is underway (with G. Weiglein et al)

• New leverage –proton momentum correlations (probes of QCD dynamics , CP- violation effects…)

LHC : ‘after discovery stage’, Higgs ID……

H

How do we know what we’ve found?

mass, spin, couplings to fermions and Gauge Bosons, invisible modes… for all these purposes the CEDP will be particularly handy !

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EXPERIMENTAL CHECKS OF DURHAM APPROACH

Up to now the diffractive production data are consistent with KKMRS results Still more work to be done to constrain the uncertainties.

• Very low rate of CED high-Et dijets, 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 (CDF).

•The ratio of high Et dijets in production with one and two rapidity gaps (CDF).

• Preliminary CDF results on exclusive charmonium CEDP.

•Energy dependence of the Rap. Gap survival (D0, CDF)

• CDP of γγ

•Leading neutron spectra at HERA.

BREAKING NEWS, CDF

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SKMRS-05

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Current projects and medium term (2006- 2008) plans

Comprehensive study of the radiative backgrounds to the H->bb CEDP,application to the Higgs physics at PC@ILC. (KRS)

Leading neutron spectra at HERA as a way to gauge the absorptive effectsand enhanced Pomeron contributions (KMR)

Detailed investigation of the MSSM Higgs sectorin diffractive processes (S. Heinemeyer, M. Tasevsky, G. Weiglein + KRS)

Prospects to study the NMSSM Higgs in diffractive processes (A. De Roeck,J. Gunion +KMR) Study of the NLL- effects in the mass-suppressed Jz=0 gg/-> qq amplitudes (A. Shuvaev +KMRS +…)

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Exclusion region

PRELIMINARY5 Higgs discovery in a Forward Proton mode

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

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Longer-term (2008-2010) plans.

Very Optimistic scenario: FP-420 is approved, and Higgs is found at the LHC.

the meticulous work on improving the accuracy of calculations to matchthe aimed for experimental precisions. An interplay with a ILC. + topics below.FP420- unfriendly scenario: Higgs is found, but FP-420 is not approved or long delayed.

the application of the ‘event colour portrait’ technique (VAK&WJS et al.)to disentangle the Higgs signal from the QCD bgds.Using the developed calc. technique for the ILC physics:+ topics below. ‘Pessimistic’ scenario: Elementary Higgs is not found and FP-420 is not

approved.

●Comprehensive soft and semi-soft physics programs for TOTEM, CMS-TOTEM and ATLAS (possibly ALICE). Photon-induced interactions at the LHC.

● Top and stop studies revisited. ● Detailed (re) analysis of the Tevatron & HERA diffractive data for purely QCD

purposes. ● QCD studies at ILC.

9First opportunity –autumn 2008 (planned LHC shutdown)

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The New UK R&D Bid

FP420 is led by the UK. The physics case is led by Durham

Close ties with Manchester and other UK FP 420’ ers.Successful annual IPPP-Manch. Forward wks (from 2001) Joint research and publications.