UK HEP Forum Cosener s house 25 th April

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

The Experimental Challenges M 2 = 1 2 S Where 1, 2 are the fractional momentum losses of the outgoing protons 420 m 308 m 215 m horizontal offset = Dx To get ~ 0. 005 proton (M ~ 70 Ge. V) 2. 5 mm from beam (10 s) pots must be > 250 m from IP -> cold region, & level 1 trigger not possible K. Österberg

The Standard model Higgs Alan Martin

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)

An example : The intense coupling regime of the MSSM e. g. m. A = 130 Ge. V, tan b = 50 (difficult for conventional detection, but exclusive diffractive favourable) L = 30 fb-1, DM = 1 Ge. V S B mh = 124. 4 Ge. V 71 3 events The intense coupling regime is where the masses mof = 135. 5 Ge. V 124 are close to each H the 3 neutral Higgs bosons 2 mother and tan. Ge. Vlarge 1 2 A = 130 b is suppressed Alan Martin Manchester Dec 2003 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 Kaidalov, Khoze, Martin, Ryskin hep-ph/0311023

The MSSM with explicit CP violation - the ‘CPX’ scenario Imagine a light scalar which couples predominantly to glue, and decays to b jets … would we see it at LEP, Tevatron or LHC? In the CPX scenario, the three neutral MSSM Higgs bosons, (CP even) h 0 and H 0, 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” M. Carena, J. Ellis, S. Mrenna, A. Pilaftsis and C. E. M. Wagner, Nucl. Phys B 659 (2003) 145

CPX MSSM Higgs CP even s in fb CP odd active at non-zero t 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 D 68 (2003) 075004 Khoze, Martin and Ryskin hep-ph/0401078

The Tevatron will provide valuable information Pomerons remnants Central exclusive - no remnants Appleby and Forshaw Phys. Lett. B 541: 108 -114, 2002 CDF Phys. Rev. Lett. 85, 4215 (2000) • The exclusive cross section ~ factorises … D Effective luminosity for D 1 D 2 of mass M at production rapidity y 59 57 A 2 33 S A 1 23 Q 2 Q 3 Q 4 Hard subprocess P cross section 1 U P 2 O Q Q 3 Q 2 S … so can be 4 checked by measuring higher P 1 D P 2 I LHC rate processes at Tevatron and Veto -> See Angela Wyatt’s talk 0 23 33

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