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Forward Physics with CMS

Forward Physics with CMS. Marek Taševský (Univ.Inst. Antwerp) DIS 04 - Štrbské Pleso 16/4 2004. Slides by Albert De Roeck (CERN). Introduction Physics Detectors options. The Large Hadron Collider (LHC). PP collisions at  s = 14 TeV 5 experiments 25 ns bunch spacing

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Forward Physics with CMS

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  1. Forward Physics with CMS Marek Taševský (Univ.Inst. Antwerp) DIS 04 - Štrbské Pleso 16/4 2004 Slides by Albert De Roeck (CERN) Introduction Physics Detectors options

  2. The Large Hadron Collider (LHC) • PP collisions at • s = 14 TeV • 5 experiments • 25 ns bunch spacing •  2835 bunches • 1011 p/bunch • Design Luminosity: • 1033cm-2s-1 -1034cm-2s-1 • 100 fb-1/year 23 inelastic events per bunch crossing In LEP tunnel (circonf. 26.7 km) TOTEM Planned Startup: April 1st 2007

  3. The CMS experiment • Tracking • Silicon pixels • Silicon strips • Calorimeters • PbW04 crystals • for Electro-magn. • Scintillator/steel • for hadronic part • 4T solenoid • Instrumented iron • for muon detection • Coverage • Tracking • 0 < || < 2.5-3 • Calorimetry • 0 < || < 5 A Hugeenterprise ! Main program: EWSB, Beyond SM physics…

  4. Diffraction and Forward Physics TOTEM: • TDR submitted in January 2004/ in the process of approval • TOTEM stand alone • Elastic scattering, Total pp cross section and soft diffraction. Totem has no central detector • TOTEM together with CMS: • Full diffractive program with central activity. TOTEM will be included as a subdetector in CMS (trigger/data stream) CMS: • EOI submitted in January 2004: • Diffractive and low-x physics part of CMS physics program • Diffraction with TOTEM Roman Pots and/or rapidity gaps • LOI in preparation for new forward detectors (CASTOR, ZDC) • Additional options being studied ATLAS: • LOI submitted (March) 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.

  5. -t=10-2 -t=10-1 The TOTEM Experiment TOTEM physics program: total pp, elastic & diffractive cross sections Apparatus: Inelastic Detectors & Roman Pots (3 stations) CMS IP 147 m 180 m 215 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 215m: 0.02 <  < 0.2 300/400m: 0.002 <  < 0.2 (RPs in the cold region)

  6. TOTEM/CMS forward detectors T1/T2 inelastic event taggers T1 CSC/RPC tracker (99 LOI)  T2 GEM or Silicon tracker (TOTEM/New)  CASTOR Calorimeter (CMS/New) TOTEM T2 5.3 << 6.7 T2 T2 T1 T1 3<  <5 T2 5< <6.5 CASTOR 9,71 λI

  7. CMS/TOTEM Study • Common working group to study diffraction and forward physics at full LHC luminosity approved by CMS and TOTEM (spring 2002) (ADR/ K. Eggert organizing so far) Use synergy for e.g. simulation, physics studies & forward detector option studies. • Common DAQ/Trigger for CMS & TOTEM • Discussions on T2 • Common simulation etc… • Share physics studies Common LOI on diffractive physics (pending LHCC approval) on the time scale of ~1 year CMS/TOTEM is the largest acceptance detector ever built at a hadron collider

  8. Total TOTEM/CMS acceptance (b*=1540m) RPs microstation at 19m? CMS/TOTEM Study CMS/TOTEM is the largest acceptance detector ever built at a hadron collider For the first time at a collider large acceptance detector which measures the forward energy flow 1 day run at large beta (1540m) and L=1029cm-2s-1: 100 million minimum bias events, including all diffractive processes >90% of all diffractive protons are detected Charged particles T1,T2 T1,T2 Roman Pots Roman Pots TOTEM+CMS Energy flux

  9. Forward Physics Program • Soft & Hard diffraction • Total cross section and elastic scattering • Gap survival dynamics, multi-gap events, proton light cone (pp3jets+p) • 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?) • 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 studies can be done best with L ~1033 (or lower)

  10. Diffraction at LHC: proton momentum loss measured in RPs • 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!

  11. DPE:  from Di-jet events • Et> 100 GeV/2 figs Pt>100 GeV/c for different Pomeron structure functions (using POMWIG generator) 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 Pomeron SFs

  12. Diffractive Higgs Production Exclusive diffractive Higgs production pp p H p : 3-10 fb Inclusive diffractive 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. … gap gap H h p p Advantages Exclusive:  Jz=0 suppression of ggbb background  Mass measurement via missing mass -jet beam dipole dipole p’ ~New: Under study by many groups p’ roman pots roman pots

  13. MSSM Higgs SM Higgs: (30fb-1) 11 signal events O(10) background events Cross section factor ~ 10 larger in MSSM (high tan) 100 fb 1fb Kaidalov et al., hep-ph/0307064 Also: Study correlations between the outgoing protons to analyse the spin-parity structure of the produced boson 120 140  See talk of A. Martin

  14. Beyond Standard Model Diffractive production of new heavy states pp p + M + p Particularly if produced in gluon gluon (or ) fusion processes Examples: Light CP violating Higgs Boson MH < 70 GeV B. Cox et al. Light MSSM Higgs hbb at large tan  Light H,A (M<150 GeV) in MSSM with large tan  (~ 30)  S/B > 10 Medium H,A (M=150-200 GeV) medium tan ? V. Khoze et al. Radion production - couples strongly to gluons Ryutin, Petrov Exclusive gluino-gluino production? Only possible if gluino is light (< 200-250 GeV) V. Khoze et al.

  15. SM Higgs Studies Needs Roman Pots at new positions 320 and/or 420 m Technical challenge: “cold” region of the machine, Trigger signals… Curves: Helsinki Group Dots: Fast sim. using DPEHIGGS MC model Mass of Higgs

  16. Diffractive Higgs Production Mass resolution vs. central mass from protons measured in roman pots assuming DxF/xF = 10-4 • Exclusive channel pp p H p advantages • Good mass resolution thanks to missing mass • method: • DM = O(1.0 - 2.0) GeV (including systematics) • Study possible in the b-quark decay mode • b-quark background suppression: (JZ =0 states)!! • Switch of dominant background (at LO)! • Inclusive production pp p+X+H+Y+p: • 100 x larger cross section but background not • suppressed (gain under study) and missing mass • less effective Mass resolution (GeV) symmetric case: Central Mass (GeV)

  17. Detectors at 300m/400m Detectors in this region requires changes in the machine • Physics Case • Can we expect to see a good signal over background?  Signal understood (cross section) ?  Needs good understanding of the background (inclusive!)  Needs more complete simulations (resolutions, etc.) • Trigger • 300m/400m signals of RPs arrive too late for the trigger  Can we trigger with the central detector only for L1? Note: L1 2-jet thresholds ET > ~150 GeV • Machine • Can detectors (RPs or microstations) be integrated with the machine? Technically there is place available at 330 and 420 m Some Major Concerns: Of interest for both ATLAS and CMS

  18. 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 above 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?

  19. Low-x at the LHC Shadowing corrections for different saturation radii R Rapidity ranges of jets or leptons vs x range ||<5 5<||<7 Log10(x) Log10(x) 7<||<9 5.5<||<7.8 Kimber Martin Ryskin Log10(x) Log10(x)

  20. Di-jets in pp scattering Measurements for low-x (BFKL) dynamics jet  jet Azimuthal decorrelation between the 2 jets versus rapidity distance between the 2 jets Large  range needed Rise?

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

  22. CMS Totem p p Two-photon interactions at the LHC Process K. Piotrzkowski WWA spectrum Reach high W values!! All events Elastic events Double tags Relative luminosity S = L/Lpp:: ~ 0.1% for W> 200 GeV Must tag protons at small |t| with good resolution: TOTEM Roman Pots!

  23. p p Two-photon interactions at the LHC Sensitivity to Large Extra Dimensions New studies: p interactions with 10-100x  Luminosity

  24. SM HIGGS case Number of Higgs events for single tags and assuming integrated lumi-nosity of 30, 0.3 and 0.03 fb-1 for pp, pAr and ArAr collisions, respectively. SUSY K. Piotrzkowski Significant production rates and very clean signatures available - both transverse and longitudinal missing energy Exclusive production! Range up to 200-250 GeV for single tags

  25. Status of the Project • Common working group to study diffraction and forward physics at full LHC luminosity approved by CMS and TOTEM (spring 2002) (ADR/ K. Eggert organizing) Use synergy for e.g. simulation, physics studies & forward detector option studies. Some of this happened e.g. RP & T2 simulation, detector options • Detector options being explored • Roman Pot/microstations for beampipe detectors at 150, 215 , add 310 & 420 m ? (cold section!) • Inelastic detectors T1 CSC trackers of TOTEM (not usable at CMS lumi) Replace T2 with a compact silicon tracker (~ CMS technology) or GEMs Add EM/HAD calorimeter (CASTOR) behind T2 Add Zero degree calorimeter (ZDC) at 140 m • Common DAQ/Trigger for CMS & TOTEM • Common simulation etc…

  26. A Forward Calorimeter (CMS) A calorimeter in the range 5.3 << 6.7 (CASTOR) Position of T2 and Castor (7/2/03) 13570 T2 CASTOR Tungsten and quartz plates Length 152 cm~ 9I Electromagnetic section 8 sectors/ needs extension APD detectors

  27. “Spectators” ZDC: zero degree calorimeter ZDC ZDC Beam pipe splits 140m from IR ZDC LOCATION M. Murray Tungsten/ quartz fibre or PPAC calorimeter EM and HAD section Funding pending in DOE BEAMS

  28. Opportunities for present/new Collaborators • CMS central detector • Diffractive Gap Trigger (possible in CMS trigger but needs to be studied) • T2 region • Calorimeter (CASTOR) • Add  granularity (silicon, PPAC,…) • Castor trigger • So far only one side of CMS equipped (500 kCHF) • T2 tracker (part of TOTEM, but still in flux…) • May need participation from CMS (if silicon option) • May need new tracker by CMS (if GEM option)… watch TOTEM TDR • Detectors at 300/400m • Completely new project • Needs new resources (there are interested parties in CMS & ATLAS) • ZDC small project but funding not yet garanteed • New detectors in the range 7< <9??? (20 m from IP)  Certainly help welcome on simulation tools, detailed physics studies…

  29. Rapidity Gaps at LHC Number of overlap events per bunch crossing versus LHC lumi distribution of nr. of int. per bunch crossing 1.1033 2.1033` 1032 1033 1034 1 int. in 22% 1 int. in 4% Doable at startup luminosity without Roman Pots!

  30. Summary • A study group has been formed to explore the common use of CMS and TOTEM detectors and study the forward region. • Physics Interest - 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…) • Probably initial run at high * (few days/weeks  0.1-1 pb-1 ) • Runs at low * (10-100 fb-1 ) • NEW: CMS officially supports forward physics as a project! • Expression of interest for the LHCC • Opportunities for present/new collaborators to join  complete forward detectors for initial LHC lumi However: Contribution to LOI needed NOW

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