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Double proton tagging at the LHC

UK HEP Forum, Cosener’s house 25th April 2004. Only 0 ++ (or 2 ++ ) systems produced. bb background strongly suppressed. Improved mass resolution. s >> M 2 ,t, (a) & (b) cancel in limit m b -> 0. Brian Cox. Double proton tagging at the LHC.

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Double proton tagging at the LHC

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  1. UK HEP Forum, Cosener’s house 25th April 2004 Only 0++ (or 2++) systems produced bb background strongly suppressed Improved mass resolution s >> M2,t, (a) & (b) cancel in limit mb -> 0 Brian Cox Double proton tagging at the LHC Very schematically it’s a glue – glue collider where you know the beam energy of the gluons - so any 0++ state which couples strongly to glue is a possibility … Forward physics with proton taggers at the Tevatron and LHC 12 - 14 Dec 2004 glodwick.hep.man.ac.uk/conference

  2. The Experimental Challenges 420 m 308 m 215 m horizontal offset = Dx To get  ~ 0.005 proton (M ~ 70 GeV) 2.5mm from beam (10s) pots must be > 250 m from IP -> cold region, & level 1 trigger not possible K. Österberg M2 = x1 x2 S Where x1,2are the fractional momentum losses of the outgoing protons

  3. The Standard model Higgs Alan Martin

  4. Particularly promising scenarios for CEDP If the coupling of the Higgs-like object to gluons is large, double proton tagging becomes very attractive • ‘Difficult’ regions of the MSSM • The MSSM with explicit CP violation (CPX)

  5. An example : The intense coupling regime of the MSSM For 5 s with300 (30) fb-1 e.g. mA = 130 GeV, tan b = 50 (difficult for conventional detection, but exclusive diffractive favourable) L = 30 fb-1, DM = 1 GeV S B mh = 124.4 GeV 71 3 events mH = 135.5 GeV 124 2 mA = 130 GeV 1 2 Alan Martin Manchester Dec 2003 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 Kaidalov, Khoze, Martin, Ryskin hep-ph/0311023

  6. The MSSM with explicit CP violation - the ‘CPX’ scenario In the CPX scenario, the three neutral MSSM Higgs bosons, (CP even) h0 and H0, and (CP odd) a mix to produce 3 physical mass eigenstates H 1 , H 2 and H 3 with mixed CP Medium grey Dark grey “there are small regions of parameter space in which none of the neutral Higgs bosons can be detected at the Tevatron and the LHC” Imagine a light scalar which couples predominantly to glue, and decays to b jets … would we see it at LEP, Tevatron or LHC? M. Carena, J. Ellis, S. Mrenna, A. Pilaftsis and C. E. M. Wagner, Nucl. Phys B659 (2003) 145

  7. CPX MSSM Higgs s in fb CP odd active at non-zero t CP even Direct evidence for CP violation in Higgs sector 0++ Selection rule Also, since resolution of taggers > Higgs width: QCD Background ~ But tt mode has only QED background B.C., Forshaw, Lee, Monk and Pilaftsis Phys. Rev D68 (2003) 075004 Khoze, Martin and Ryskin hep-ph/0401078

  8. The Tevatron will provide valuable information • The exclusive cross section ~ factorises … Hard subprocess cross section P1U P2O Effective luminosity for production of mass M at rapidity y … so can be checked by measuring higher rate processes at Tevatron and LHC -> See Angela Wyatt’s talk Q4 Q3 Q2 Q2 S D Q3 Q4 S A1 D1 A2 D2 P1D P2I Veto 57 59 23 0 33 23 33 Pomerons remnants Central exclusive - no remnants Appleby and Forshaw Phys.Lett.B541:108-114,2002 CDF Phys. Rev. Lett. 85, 4215 (2000)

  9. Summary and work in progress • Real discovery potential in certain scenarios • Possibility to measure Higgs branching ratio to e.g. b or t - complementary information to conventional searches • Azimuthal asymmetries 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 • Need independent theoretical and experimental verification of the cross section and background predictions (Manchester and Durham collaborating) • Need more work on level 1 trigger - can we do it? (see e.g Monika Grothe at LHC / HERA workshop)http://www.hep.ua.ac.be/heralhc/ • Need independent detailed studies of mass resolution and acceptance of pots • Need a well presented physics case and must prove the experimental needs lead to minimal disruption to current LHC program

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