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Diffraction and Forward Physics at the LHC

Diffraction and Forward Physics at the LHC. Albert De Roeck CERN and University of Antwerp. Diffraction at LHC:. PP scattering at highest energy Soft & Hard Diffraction  < 0.1  O(1) TeV “Pomeron beams“ E.g. Structure of the Pomeron F(,Q 2 )

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Diffraction and Forward Physics at the LHC

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  1. Diffraction and Forward Physics at the LHC Albert De Roeck CERN and University of Antwerp

  2. Diffraction at LHC: • PP scattering at highest energy • Soft & Hard Diffraction  < 0.1  O(1) TeV “Pomeron beams“ E.g. Structure of the Pomeron F(,Q2)  down to ~ 10-3 & Q2 ~104 GeV2 Diffraction dynamics? Exclusive final states ? • Gap dynamics in pp presently not fully understood!  = proton momentum loss Reconstruct  with roman pots

  3. The LHC Machine and Experiments • ATLAS/CMS Coverage • Tracking 0 < || < 3 • Calorimetry 0 < || < 5 • Consider additions/upgrades Experiments for Forward Physics • TOTEM & LHCf (proposed) (LHCf) pp collisions at 14 TeV totem

  4. Diffraction and Forward Physics at LHC TOTEM: • Approved July 2004 (TDR of TOTEM web page http://totem.web.cern.ch/Totem/) • TOTEM stand alone • Elastic scattering, total pp cross section and soft diffraction. CMS: • EOI submitted in January 2004: /afs/cern.ch/user/d/deroeck/public/eoi_cms_diff.pdf • Diffraction with TOTEM Roman Pots and/or rapidity gaps • Technical Proposal in preparation for new forward detectors (CASTOR, ZDC,+…) • Diffractive and low-x physics part of CMS physics program (low + high ) CMS+TOTEM: • Prepare common LOI due in Summer 2006(M. Grothe/V. Avati organizing) • Full diffractive program with central activity. TOTEM will be included as a subdetector in CMS (trigger/data stream) ATLAS: • LOI submitted (March 04) for RP detectors to measure elastic scattering/ total cross sections/luminosity. Diffraction will be looked at later ALICE, LHCb: no direct forward projects plans but keeping eyes open. FP420: Collaboration for R&D and feasibility study for detectors at 420 m

  5. Forward Coverage: TOTEM/LHCf TOTEM: measuring the total, elastic and diffractive cross sections Add Roman pots at 150-220m (and inelastic telescopes) to CMS interaction regions.  Common runs with CMS planned tot ~ 1% precision LHCf: measurement of photons and neutral pions in the very forward region of LHC Add an EM calorimeter at 140 m from the Interaction Point (of ATLAS) Connection with cosmic rays

  6. M. Deile HCP05

  7. M. Deile HCP05

  8. Forward Detectors in CMS/ATLAS IP5 TOTEM: T1 3.1<  <4.7 TOTEM T2 5.3< <6.7 CMS Castor 5.25< <6.5 CMS/TOTEM: Extend the reach in  from ||<5 to || <6.7 + neutral energy at zero degrees (ZDC) CMS+TOTEM: first full acceptance detector? IP1 ATLAS: Roman Pots at 240 m Cerenkov Counter (LUCID) 5.4 << 6.1 + neutral energy at zero degrees

  9. CMS/TOTEM: a “complete” LHC detector CMS/TOTEM will be the largest acceptance detector ever built at a hadron collider +ZDC K. Eggert Still studying other regions (19m, 25m, 50m…)

  10. Forward Physics Program • Soft & Hard diffraction • Total cross section and elastic scattering (TOTEM, precision of O(1)%) • Gap survival dynamics, multi-gap events, proton light cone (pp3jets+p), odderon • Diffractive structure: Production of jets, W, J/, b, t, hard photons • Double Pomeron exchange events as a gluon factory (anomalous W,Z production?) • Diffractive Higgs production, (diffractive Radion production?), exclusive SPE?? • SUSY & other (low mass) exotics & exclusive processes • Low-x Dynamics • Parton saturation, BFKL/CCFM dynamics, proton structure, multi-parton scattering… • New Forward Physics phenomena • New phenomena such as DCCs, incoherent pion emission, Centauro’s • Strong interest from cosmic rays community • Forward energy and particle flows/minimum bias event structure • Two-photon interactions and peripheral collisions • Forward physics in pA and AA collisions • Use QED processes to determine the luminosity to 1% (ppppee, pppp) Many of these topics can be studied best at startup luminosities

  11. DPE:  from Di-jet events • Et> 100 GeV/2 figs Pt>100 GeV/c for different structure functions d (pb) events H1 fit 6 (1-x)5 H1 fit 5 x(1-x) H1 fit 6 H1 fit 4 (x 100)   =jets ET e-/(s) ; from Roman Pots; ET and  from CMS High  region probed/ clear differences between different SFs

  12. Novel Channels: eg Diffractive Top Decay Channel Antonio Vilela (Rio De Janeiro) Top mass peak Efficiency still to be increased With low Etjet cuts O(100) events/10 pb-1

  13. p + p  B + X Diffractive J/ Production D.J, Damiao et al Rio de Janeiro  J/Y+-. After selection and 10 fb-1

  14. Low-x at the LHC LHC: due to the high energy can reach small values of Bjorken-x in structure of the proton F(x,Q2) Processes:  Drell-Yan  Prompt photon production  Jet production  W production If rapidities below 5 and masses below 10 GeV can be covered  x down to 10-6-10-7 Possible with T2 upgrade in TOTEM (calorimeter, tracker) 5<< 6.7 ! Proton structure at low-x !! Parton saturation effects?

  15. High Energy Cosmic Rays Cosmic ray showers: Dynamics of the high energy particle spectrum is crucial Karlsruhe, La Plata Interpreting cosmic ray data depends on hadronic simulation programs Forward region poorly know/constrained Models differ by factor 2 or more Need forward particle/energy measurements e.g. dE/d…

  16. Exclusive Central Higgs Production Exclusive central Higgs production pp p H p : 3-10 fb Inclusive central Higgs production pp  p+X+H+Y+p : 50-200 fb -jet E.g. V. Khoze et al M. Boonekamp et al. B. Cox et al. V. Petrov et al. Bartels et al. Brodsky et al. gap gap H h p p Advantages exclusive production:  Jz=0 suppression of ggbb background  Mass measurement via missing mass -jet beam dipole dipole M = O(1.0 - 2.0) GeV p’ p’ roman pots roman pots

  17. Exclusive Central Higgs Production • Selection rules mean that central system is (to a good approx) 0++ • If you see a new particle produced exclusively with proton tags you know its quantum numbers • CP violation in the Higgs sector shows up directly as azimuthal asymmetries • Proton tagging may be the discovery channel in certain regions of the MSSM • Tagging the protons means excellent mass resolution (~ GeV) irrespective of the decay products of the central system • Unique access to a host of interesting QCD Very schematically: exclusive central production is a glue – glue collider where you know the beam energy of the gluons - source of pure gluon jets - and central production of any 0++ state which couples strongly to glue is a possibility …

  18. Exclusive Higgs production Standard Model Higgs b jets : MH = 120 GeV s = 2 fb (uncertainty factor ~ 2.5) MH = 140 GeV s = 0.7 fb MH = 120 GeV :11 signal / O(10) background in 30 fb-1 with detector cuts H WW* : MH = 120 GeV s = 0.4 fb MH = 140 GeV s = 1 fb MH = 140 GeV :8 signal / O(3) background in 30 fb-1 with detector cuts • The b jet channel is possible, with a good understanding of detectors and clever level 1 trigger (need trigger from the central detector at Level-1) • The WW* (ZZ*) channel is extremely promising : no trigger problems, better mass resolution at higher masses (even in leptonic / semi-leptonic channel) • If we see SM Higgs + tags - the quantum numbers are 0++ Phenomenology moving on fast See e.g. J. Forshaw HERA/LHC workshop

  19. Higgs Studies • Cross section factor • ~ 10-20 larger in MSSM • (high tan) • Few 100 events with ~ 10 background events for 30 fb-1 100 fb Kaidalov et al., hep-ph/0307064 1fb Study correlations between the outgoing protons to analyse the spin-parity structure of the produced boson 120 140 A way to get information on the spin of the Higgs ADDED VALUE TO LHC

  20. Measuring the Azimuthal Asymmetry Khoze et al., hep-ph/0307064 Azimuthal correlation Between the tagged protons Allows to eg to differentiate O+ from O- Does not include absorptive corrections (S2), see ref above

  21. “lineshape analysis” J. Ellis et al. hep-ph/0502251 Scenario with CP violation in the Higgs sector and tri-mixing

  22. Detailed Simulation Studies Signals and background for different Higgs masses Detailed studies ongoing Fast detector simulation Boonekamp/ATLAS Royon,Tasevsky/CMS Include exclusive and inclusive bb background Include missing mass resolution from the tagged protons 100 fb-1 First look/needs to be optimized

  23. Models… Different models give different predictions for The cross sections The mass/energy dependence of the cross sections Almost all calculations now converge to a cross section of 2-10 fb for a light Higgs J. Forshaw BL Bialas Landshof (soft Pomeron) KMR: Khoze Martin Ryskin Tevatron can test these models

  24. Information from Tevatron! Study of central exclusive processes V. Khoze et al., hep-ph/0403218 V. Khoze et al., hep-ph/0409037 pp p + c +p pp p + dijets+p Now observed at the Tevatron! Consistent with KMR (R. Walny) D. Goulianos pp p +  +p

  25. Central Exclusive Dijet Production Cox and Pilkington Tevatron prospects DPEMC ExHume CDF runII analysis cuts Rjj > 0.8 20-120 pb Models predict a different pt spectrum for the jets Dedicated analyses to detect central exclusive production would be useful (other jet algos)

  26. Roman pot acceptances TOTEM (ATLAS) FP420 Low *: (0.5m): Lumi 1033-1034cm-2s-1 215m: 0.02 <  < 0.2 300/400m: 0.002 <  < 0.02 Detectors in the cold region are needed to access the low  values FP420 R&D Study

  27. Mass Resolution Helsinki group Mass resolution 1-2% for symmetric events Still being optimized Can we improve the resolution?  would increase significance

  28. FP420 R&D Study • Feasibility study and R&D for the development of detectors to measure protons at 420 m from the IP, during low  optics at the LHC • Main physics aim pp  p+ X + p • Higgs, New physics • QCD studies • Photon induced interactions • Main study aims • Mechanics/stability for detectors at 420 meter (cryostat region) • Detectors to operate close to the beam (3D silicon? Diamond?) • Fast timing detectors (10-20 picosecond resolution) • RF issues, integration, precision allignment, radiation, resolution,… • Trigger/selection issues/pile-up for highest luminosity To be built/deployed by CMS and/or ATLAS, when successful • Succesful fundign bids in UK, Belgium,… • Collaboration web page: http://www.fp420.com Note: this is an open collaboration Contacts: B. Cox (Manchester), A. De Roeck (CERN)

  29. FP420 CERN-LHCC-2005-025 LHCC-I-015 FP420 : An R&D Proposal to Investigate the Feasibility of Installing Proton Tagging Detectors in the 420m Region at LHC M. G. Albrow, T. Anthonis, M. Arneodo, R. Barlow, W. Beaumont, A. Brandt, P. Bussey, C. Buttar, M. Capua, J. E. Cole, B. E. Cox,*, C. DaVià, A. DeRoeck,*, E. A. De Wolf, J. R. Forshaw, J. Freeman, P. Grafstrom,+, J. Gronberg, M. Grothe , J. Hasi, G. P. Heath, V. Hedberg,+, B. W. Kennedy, C. Kenney, V. A. Khoze, H. Kowalski, J. Lamsa, D. Lange, V. Lemaitre, F. K. Loebinger, A. Mastroberardino, O. Militaru, D. M. Newbold, R. Orava1, V. O’Shea, K. Osterberg, S. Parker, P. Petroff, J. Pinfold, K. Piotrzkowski, M. Rijssenbeek, J. Rohlf, L. Rurua, M. Ruspa, M. G. Ryskin, D. H. Saxon, P. Schlein, G. Snow, A. Sobol, A. Solano, W. J. Stirling, M. Tasevsky, E. Tassi, P. Van Mechelen, S. J. Watts, T. Wengler, S. White, D. Wright LOI submitted to the LHCC end of June New institutes since LOI/ new list in prepartion 58 authors 29 institutes Expertise with forward detectors from H1, ZEUS, CDF, D0,…

  30. Detectors at 420m • Cold section: Detectors have to be integrated with cryostat Two options discussed with the machine Prefered option: 15m cold-warm transition with the detectors at ‘room’ temperature.  Many machine components already ordered, some already delivered  Machine wants “easy” start-up/no perturbation  Change means an “LHC upgrade” (phase II)  aim for 2009 run

  31. New Forward Detector The connecting cryostat today

  32. Detectors at 420m

  33. Detectors & Mechanics -roman pot concept for a compact detectors ..or a moving beampipe as used at HERA Important will be overall stability and integration with precision beam position monitor to reach O(10)m Need to approach beam to mm level

  34. Fast Timing Detectors Put at back of 420m tracking high precision timing counters. Suggested in Tevatron LOI: Quartz Cerenkov + ~ Microchannel PMT Then said 30 ps(?). Now tested (Japanese Gp)  10 ps Other option: Gas Cerenkov Check that p’s came from same interaction vertex (& as central tracks) x tR tL t_int t tL z_vtx tR z Expected to be particularly useful/essential at high luminosity

  35. Summary • Diffractive and forward physics is on the physics program of LHC experiments. CMS+TOTEM working towards a common TDR. ATLAS developing Roman Pots for total cross section/luminosity.  Diffractive and forward physics will be done from the start at the LHC  Don’t hesitate to come up with new ideas, new measurements, new test! • Upgrades for the experiments are being proposed • In particular large momentum for 420m region is materializing. FP420 • Detector to complement ATLAS and/or CMS in the forward region • CMS/ATLAS expand coverage in the forward coverage • Large field of Physics Topics - Hard (& soft) diffraction, QCD and EWSB (Higgs), New Physics - Low-x dynamics and proton structure - Two-photon physics: QCD and New Physics - Special exotics (centauro’s, DCC’s in the forward region) - Cosmic Rays, Luminosity measurement, pA, AA…

  36. Backup

  37. -t=10-2 -t=10-1 Roman Pot Detectors (TOTEM) TOTEM physics program: total pp, elastic & diffractive cross sections Apparatus: Inelastic Detectors & Roman Pots (2 stations) CMS IP 150 m 220 m High * (1540m): Lumi 1028-1031cm-2s-1(few days or weeks) >90% of all diffractive protons are seen in the Roman Pots. Proton momentum measured with a resolution ~10-3 Low *: (0.5m): Lumi 1033-1034cm-2s-1 220m: 0.02 <  < 0.2 300/400m: 0.002 <  < 0.02 (RPs in the cold region/ under discussion in FP420)  = proton momentum loss

  38. MH Acceptance Helsniki Group TOTEM study FP420 study Model Dependence Need HERA and/or Tevatron to referee Otherwhise wait for LHC data

  39. Anomalous WW Production Alan White: theory of supercritical pomeron reggeized gluon+many (infinite) wee gluons • color sextet quarks required by asymptotic freedom, have strong colour charge, (at least) few 100 GeV constituent mass • Sextet mesons  EWSB • UDD neutron dark matter candidate • Explain high energy cosmic rays, Knee? • Color sextet quarks couple strongly to W and Z and to the pomeron • Phenomenology: Anomalous production of WW when above threshold ie. At the LHC (with possibly some onset already detectable at the Tevatron color color triplets sextets u c t U d s b D • Measure exclusive WW,ZZ cross sections in DPE at the LHC Expected Cross section orders of magnitude larger than in SM

  40. Radions Radions (graviscalars) RS models: quantum excitations of the brane separation  Radion couplings to Gauge bosons and Fermions similar to SM Higgs   mixing to H  causes shift in gHVV and gHff couplings Couplings to  and gg receive anomalous contributions EW constraints Horror! ggH cross section can disappear!!  Gunion, Toharia & Wells hep-ph/0311219

  41. Radions Petrov Ryutin Radions like to couple to gluons Large production rates in DPE Large rate of bb fb fb

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