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Physics at CMS

Physics at CMS. Status of CMS and US CMS Dan Green Fermilab October 6, 2004. Outline. LHC Accelerator CMS Detector Trigger/DAQ - L1T, HLT Higgs gg Fusion Associated Production, WW Fusion SUSY Exotica (Composites, Z’, Extra Dimensions, …) HI Program. LHC Significance.

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Physics at CMS

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  1. Physics at CMS • Status of CMS • and • US CMS • Dan Green • Fermilab • October 6, 2004

  2. Outline • LHC Accelerator • CMS Detector • Trigger/DAQ - L1T, HLT • Higgs • gg Fusion • Associated Production, WW Fusion • SUSY • Exotica (Composites, Z’, Extra Dimensions, …) • HI Program

  3. LHC Significance LHC will be the first big jump in C.M. energy and luminosity in 20 years. Based on the last 40 years of HEP, new phenomena are expected.

  4. LHC Schedule Blue is the planned schedule. Red is just in time. Issues of SC cable and cold masses (vendors) are solved. Testing at CERN is now the CP for dipoles – and cryoline installation. There is no reason to assume that the CERN schedule will not be ~ met. Three shift operation -> sector test in Spring 2006. Collisions in April 2007. Physics run (10 fb -1) starting in late 2007 ?.

  5. The CMS Detector SUPERCONDUCTING COIL CALORIMETERS ECAL HCAL IRON YOKE TRACKER Basic Choices: Strong, large B field (4T) All Si tracking (L) Best possible ECAL dE/E Robust Muon - yoke MUON ENDCAPS MUON BARREL

  6. Magnet Coil : ~ 2/3 done • Expect the 5 modules at CERN by Nov., 2004 • Start cooling in March 2005 • Complete SX5 magnet test on Oct, 2005 • Lower CMS into UX5 – 1.5 yr before LHC beam

  7. Trial Test of Coil Insertion Simulation ofcoil radial extent Assembly of CMS proceeding in the surface hall (SX5).

  8. CMS Tracker – All Si Pixel End cap –TEC- Outer Barrel –TOB- Inner Barrel –TIB- Inner Disks –TID- 2,4 m 5.4 m 210 m2 of silicon sensors 6,136 Thin detectors (1 sensor) 9,096 Thick detectors (2 sensors) 9,648,128 electronics channels

  9. ECAL Test Beam Module PbWO4 crystals. Fast and rad hard but light output is low  APD. Electronics is IBM 0.25 um which is radiation hard.

  10. HCAL : HB and HE Scintillator + brass. Use HPD and QIE. Back-flange 18 Brackets 3 Layers of absorber

  11. Endcap Muon Chambers Endcap return yoke and CSC

  12. Detector Performance/Status • TTC vetted, 25 nsec test beam in 2003, ESR passed, 0.25 m commonality, GOL standard. • Pixels – occupancy ~0.0001, impact ~ 15 m, R&D. production in 2005. • SiTrkr – pre-production, dpT/pT~0.02 at 100 GeV. Full production in 2005. • Calor – production, timing with laser, calib with construction data. Testbeam  G4 data set, cosmic muons. Minbias, Z -> ee, t -> Wb, J-J and J -  in situ. • Muons – production, slice tests, alignment, trigger primitives on cosmic muons.

  13. DAQ TDR: Level-1 Trigger • Information from calorimeters • and muon detectors • Electron/photon triggers • Jet and missing ET triggers • Muon triggers High efficiency for discovery level Physics with ~ 30 kHz bandwidth (~ 3x headroom)

  14. Level-1 Trigger Table (1034) L1 Trigger on leptons, jets, missing ET and calib/minbias

  15. Minimum Bias Events • Pileup must be understood in dealing with Physics. • Isolation criteria are applied and efficiency must be understood. • A fast calibration to reduce the number of calorimeter constants • Use  symmetry of deposited energy to inter-calibrate calorimeter towers within rings of constant  D.Futyan, C.Seez CMS Note 2003-031 Barrel

  16. DAQ TDR: DAQ • Event size: 1MB from ~700 front-end electronics modules • Level-1 decision time: ~3s — ~1s actual processing(the rest in transmission delays) • DAQ designed to accept Level-1 rate of 100kHz • Modular DAQ: 8 x 12.5kHz units • HLT designed to output O(102)Hz – rejection of 1000 • DAQ factorizes by 8x

  17. HLT Selection -  • -leptons • Level-2: calorimetric reconstruction and isolation • Very narrow jet surrounded by isolation cone • Level-3: tracker isolation

  18. super-cluster basic cluster HLT Electron Selection: Level-2 • “Level-2” electron: • Search for match to Level-1 trigger • Use 1-tower margin around 4x4-tower trigger region • Bremsstrahlung recovery “super-clustering” • Select highest ET cluster • Brem recovery: • Road along  in narrow -window around seed • Collect all sub-clusters in road  “super-cluster”

  19. Full pixel system Staged option HLT Electron Selection: Level-2.5 • Most e triggers are neutrals  use pixel information • Very fast, large rejection with high efficiency • Before most material before most bremsstrahlung, and before most conversions • Number of potential hits is 3, so demanding  2 hits is quite efficient

  20. HLT and Physics Efficiency

  21. HLT Performance — Efficiency

  22. Preparing for Physics • To do the Physics well, we must – by 2007: • Commission – SX5, slice tests, trigger primitives, portable DAQ, pulsers, lasers, cosmics • Calibrate – test beam, sources, lasers, muons • Align – muons, photogrammetry, proximity sensors • Deploy Core Software – data challenges, calib samples (W, Z, JJ, J, minbias)

  23. SWC Challenges

  24. Physics TDR goals • Physics TDR is a test of validity/readiness of CMS to extract initial Physics • Readiness of software, computing and people’s knowledge, skills • Next step is the Physics TDR so that • It is: • an opportunity to write, debug, clean, re-write our software • a test/chance to tune data-handling and distributed analysis • re-evaluate our (detector/software) strengths and weaknesses • the way to identify priorities at T0, plus general time-scales • e.g. SUSY shows up quickly • a way to learn the new system (start in late 2003, end in 2005) • Necessary input to major computing procurements in 2006.

  25. Higgs Production

  26. Higgs Decay Modes Goal is to measure mass, total width and several partial widths to confront the SM incisively. At low mass, several couplings are measurable. At higher masses WW and ZZ dominate.

  27. “Higgs” Quantum Numbers • If the 2 photon mode is observed then “H” is not a vector (Yangs’ theorem). • If the “H” is the SM Higgs then the leptons are ~ collinear in a WW decay. • If the ZZ decay is seen then a P = + state has decay planes aligned – P = - has planes orthogonal .

  28. Associated Production - Htt H is radiated in a tt final state. At low H mass the cross section is sufficient to extract a clean signal in the dominant H -> bb decay mode. In addition, a “control” sample arises from the ttZ state with a leptonic Z decay (same Feynman diagrams).

  29. Htt Associated Production Good b tagging is clearly essential. ttZ can be used to measure the background in bb using leptonic Z decays. Most background processes have large scale uncertainties.

  30. H Production from W+W Use the EW radiation of a W by a quark. The “effective W approximation” analogous to the WW approximation. Need good jet coverage to low PT and small angles. Cross section depends only on the Higgs coupling to W, Z.

  31. qqH,H -> W+W* -> SM H leads to ~ collinear and low mass lepton pairs. qqH is most useful for H masses > 140 GeV.

  32. Higgs Summary in CMS For 10 fb-1, or 1 year at 1/10 of design luminosity almost all the allowed range for a SM Higgs is covered. CMS must be ready to quickly and incisively analyze the early LHC data. qqW, WW*, ZZ* are the discovery modes at low mass.

  33. Higgs Self Coupling Baur, Plehn, Rainwater HH  W+ W- W+ W-   jj jj Find the Higgs? If the H mass is known, then the SM H potential is completely known  HH prediction. If H is found, measure self-couplings, but ultimately SLHC is needed. The plan is for 10x increase in luminosity ~ 2013.

  34. WW Fusion into ZZ No Higgs? Look at VV scattering. Process depends only on VVV, VVVV couplings. Not viable at Tevatron. In SM cross section -> a constant, angular distribution is F/B peaked, and WLWL flux dominates. If no H then possibly large enhancement due to TT scattering.

  35. W+W -> Z + Z Angular Distribution If there is a SM H then the distribution is very F/B peaked. If not, then the cross section may have a dramatic (~ 80 x) increase and the angular distribution may become isotropic – e.g. pure quartic. Need SLHC to push to ZZ masses > 1 TeV.

  36. SUSY ? • Why SUSY? • GUT Mass scale, unification • Improved Weinberg angle prediction • p decay rate • Neutrino mass (seesaw) • Mass hierarchy – Planck/EW • String connections MMSM has ~ SM light h and ~ mass degenerate H,A. LSP is neutralino. Squarks and gluinos are heavy.

  37. WMAP and Other Constraints LEP2 g-2 WMAP LSP is neutral

  38. SUSY Cross Sections at LHC Squarks and gluinos are most copious (strong production). Cascade decay to LSP ( )  study jets and missing energy. E.g. 600 GeV squark. Dramatic event signatures and large cross section mean we will discover SUSY quickly, if it exists.

  39. SUSY – Mass “Reach” 1 year at 1/10 design luminosity. SUSY discovery would happen quickly. WMAP

  40. SUSY – Mass Scale Will immediately start to measure the fundamental SUSY parameters. With 4 jets + missing energy the SUSY mass scale can be established to 20 %. Effective mass “tracks” squark/gluino mass well 1 year at l/10th design luminosity

  41. Sparticle Cascades Use SUSY cascades to the stable LSP to sort out the new spectroscopy. Decay chain used is : Then And Final state is

  42. Sparticle Masses An example of the kind of analysis done, from 1 year at 1/10th design luminosity. 2-body decay: edge in Mll 10 fb-1

  43. Full CMS Exposure – Reconstruction of Heavy States

  44. h Decays to b pairs SUSY Higgs must be light, < 130 GeV Signature: B-jets + lepton + ETmiss  Requires b-tagging + jet counting + full calorimeter coverage for ETmiss

  45. A to  +  to Leptons Fast simulations of b and tau tags. Tau decays to leptons. Background from Z, tt, Wtb

  46. A,H to  +  to Hadrons Even in the minimal model, there is a large parameter space. This study uses hadronic tau decays. A and H are nearly mass degenerate.

  47. H+-> t + b Charged Higgs decay into quarks. Top decays to W+b with W decay to leptons supplying the trigger. H couples preferentially to high mass t quark.

  48. Heavy SUSY Higgs - 10 fb-1 A / H  m mtan b=30, mA=130 GeV A / H  t ttan b=40, mA=200 GeV Some parts of the parameter space are not covered using dilepton decays of H,A.

  49. Composites - Jets No Higgs? No SUSY? Weak interactions will become strong. 2-jet events: expect excess of high-ET centrally produced jets if quarks are composites (a la Rutherford). • is the jet-jet C.M. • scattering angle. • If contact interactions • excess at low , S wave scattering . Reach of CMS is ~ 20 TeV. Can Push up with SLHC.

  50. Early Physics Reach – q* If the calorimetry is understood, resonances up to a few TeV in mass are accessible early in the LHC run. (R. Harris) SLHC gives ~ 20% increase in mass reach.

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