1 / 37

BSM at the LHC

BSM at the LHC. Dirk Zerwas LAL Orsay. Lecture I: LHC and the Detectors Standard Model Lecture II: The standard model Higgs boson The supersymmetric Higgs bosons Lecture III: Supersymmetry Exotics. LHC. LHC. p roton- p roton collisions E beam =7TeV s = 14TeV

moke
Télécharger la présentation

BSM at the LHC

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. BSM at the LHC Dirk Zerwas LAL Orsay • Lecture I: • LHC and the Detectors • Standard Model • Lecture II: • The standard model Higgs boson • The supersymmetric Higgs bosons • Lecture III: • Supersymmetry • Exotics

  2. LHC LHC • proton-proton collisions • Ebeam=7TeV • s = 14TeV • 0.15-20*s effective • tunnel circumference: ~27km ILC 2 Multi-purpose detectors: ATLAS, CMS B-Physics: LHCb Heavy-ion physics: ALICE Totem

  3. LHC R=p/(B q c) B=8-9T supraconducting P=7TeV c=3*108m/s R=2.7km LHC: 4.3km Straight sections ALL Dipoles installed

  4. 1600 superconducting magnets…. Preparations started in 1990… Installation started in 2001…

  5. standard refrigerator: 276K LHC: a 27 km fridge at 1.9K • energy in beams: a Boeing 737 at landing speed • 60 kg of TNT (beam dump) 37000 tons of equipment 1 year of cooldown 120 tons of Helium (1 truckload=5t)!

  6. LHC: 2008/2009 Stage I II III 2008 No beam Beam We are here III 2009 No beam Beam • 2008: • Goal 5TeV (Magnets) • 43/156 bunches per beam (of 2800) • 75ns (13.3MHz) • 25ns (nominal: 40MHz)

  7. LHC: integrated Luminosity ~ 45% of nominal I L: luminosity N=σ∫Ldt t typically 107s L=1033cm-2s-1 10fb-1 p.a. ~ 25% of nominal I L=1032cm-2s-1 1fb-1 p.a. • bunch 1011 protons • every 8m • 40Mhz • reality ~ 32MHz • (empty bunches) 75ns 2007/2008 43/156 Bunches 25ns PhaseI End 2008

  8. LHC: comparison to other Machines • Rule of thumb: • around 2010 ~10fb-1 p.a. • well after 2010 ~100fb-1 p.a. • Beam (L=1034, 1.1x 1011 p/bunch) • 60 kg TNT • fully loaded Airbus 320 at landing speed

  9. ATLAS and CMS Length: 45m Radius: 12m Weight: 7000Tonnen Readout Channels: 108 3000km cables • Track reconstruction (|η|<2.5, B=4T) • Si Pixels and Strips • Calorimeter (|η|<5) • EM: PbWO4 2%/E0.7% • HAD: Brass/Scint., Fe/Quartz (fwd) • Muon chambers (|η|<2.7): • Solenoid Return Yoke instrumented with Muon chambers Length: 22m Radius: 7m Weight: 12500Tonnen • Track Reconstruction (|η|<2.5, B=2T) • Si Pixels and Strips • Detector for Transition Radiation (TRT) for PID • Calorimeter (|η|<5) • EM: Pb-LArgon 10%/E0.7%, long. Segm. • HAD: Fe/Scintillator (central), Cu-W-Lar (fwd) • Muon chambers (|η|<2.7): • Toroids with Muon chambers (MDT)

  10. CMS = Compact Muon Solenoid Length: 22m Radius: 7m Weight: 12500 tons

  11. ATLAS= A Toroidal Lhc ApparatuS Length: 45m Radius: 12m Weight: 7000tons = 100 Boeing 747 Readout channels: 100Million 3000 km cables

  12. building 40 at CERN 6 stories

  13. Event reconstruction Muons: InnerDetector and muon detectors Electrons/photons: EM Calorimeter Jets: Calorimeters Tracks: InnerDetector (with lifetime information for b-tagging) Electrons and Photons:

  14. Before Physics: Calibration Events per Second 1033 cm-2s-1 Events for 10fb-1: W eν, μν 150 M Z  ee, μμ, ττ je 15 M tt 8 M Jets (>200GeV pT) 1000 M 108 107 105 103 10 10-1 10-3 • Trigger • Calibration and Alignment of the detectors: • Electronic Calibration • In situ Calibration and Alignment: • Zee, Zμμ: Alignment, Calibration ECAL (Z mass), • Particle-ID, muon chambers • W lν : Energy/Momentum Calorimeter/Tracker • tt  bWbW  blν bjj : Reconstruction W from hadronic decay • Z ττ: tau-Lepton Reconstruction (Z mass, Efficiency), • ETmiss • γ+Jets, Z(ll) +Jets: Jet Calibration (Recoil against Z,γ) JES: 1% LES: 0.1% ETmiss: (0.5-1)/ET

  15. Particle Reconstruction: electrons/photons • The reconstruction sequence for electrons and photons: • Calibration of Electronics and Alignment • Clustering (Sliding Window) • Corrections at the cluster level: • position corrections • correction of local response variations • corrections for losses in upstream • (Inner detector) material and longitudinal leakage • Matching with Tracks • Identification • 2nd stage reco: • Refinement of corrections depending on the particle type (e/γ) • Bremfit/Gaussian Sum Filter • uniformity 0.7% with a local uniformity • in ΔηXΔφ=0.2x0.4 better than 0.5% • inter-calibrate region with Zee

  16. Energy calibration for electrons and photons Optimize Energy resolution AND linearity! 100GeV Systematics at low energy ~0.1 % Testbeam: Achieved better than 0.1 % over 20-180 GeV 0.1%-0.2% spread from 10GeV to 1TeV over all eta! Essential to mesure particle masses correctly with the best precision E loss upstream of PS E loss PS and calo calo sampling fraction+ lateral leakage E dependent Longitudinal leakage

  17. Uniformity and Identification Uniformity: ensure same energy response  Higgs (later) Identification: differentiate electrons from jets  Large QCD cross section rms 0.62% 0.45% 0.49%

  18. Jets and ETmiss Calibration e/pi response Jet clustering Jet resolution: 60%/E  3% Jet energy scale: 1%

  19. ETmiss Typical signature of SUSY compensation for dead matter etc ETMiss at 2000GeV: ATLAS σ=20GeV CMS σ=40GeV

  20. Trigger@LHC

  21. Trigger@LHC: Example of a typical menu

  22. Luminosity Measurements at the LHC 100fb-1  25 interactions per beam crossing Instantaneous luminosity decreases with beam lifetime Integrated Luminosity: N = σ * L (every rate/Xsection measurement depends on it) 1.Online measure events in 3<|η|<5 Counting zero ET towers (ET<0.5GeV): 2. Measure elastic cross section at small angles TOTEM at 150m, 200m Use optical theorem to relate total Xsection to elastic cross section extrapolated to 0 Measurements done at 1028cm-2s-1 Extrapolation of beam optics necessary Precision on σtot ~1% 3.Standard Candles: W production: 300Hz Z production: 30Hz (PDF uncertainty) Deviation at High Luminosity

  23. Minimum Bias A glossary: Minimum Bias: Trigger thresholds “minimal”, measures the total Xsection Underlying event:= “rest” when subtracting “hard process”, e.g. production Z Minimum Bias: Large uncertainties for the extrapolation from TeVatron to LHC

  24. W± Standard Model: W production Parton collisions (ex quark): Q2: square of momentum transfer Tevatron Rapidity: Pseudo-rapidity: -ln (tan θ/2) (polar angle) Masses neglected x: fraction of proton momentum gluon pdf The LHC is a gluon-collider!

  25. Standard Model: QCD • Jet-Production • with 10fb-1 • compare with NLO • BUT: • E-Calibration • prediction for PT >1TeV CMS CMS • large errors above 1TeV • energy scale • PDFs

  26. The Standard Model: W Mass Sensitivity to mW (leptonic decays, hadronic case hopeless)

  27. The Standard Model: W Mass 10fb-1 Selection: PT(lepton)>25GeV ETmiss> 25GeV Jet Veto PT>30GeV Statistics 15 Tot. Exp. <20 Scale Method: Treat Z as W and shift spectra muon electron

  28. BSM: Di-boson Production TripleGaugeCouplings (TGC): WW+γ ou WZ(ll) 300fb for PT(γ)>100GeV • Selection: • PT(γ)>100GeV • PT(Lepton)>40GeV • mT>35GeV • isolation of Photon and Lepton • Jet Veto Wγ frame W rest frame λγ=0.01 D0 (2005) (162pb-1): -0.93<Δκγ<0.97 |λγ|<0.22 LEP: g1Z=0.984±0.02 κγ=0.973±0.045 λγ=-0.028 ±0.021

  29. The top quark Indirect sensitivity to the Higgs boson mass TeVatron 2008: 172.4 ± 1.2 GeV (0.7%)

  30. Production and decay of top quarks Decay (before hadronization): short lifetime : top ~ 410-25 s decay channels: t  W+b because mtop > MW with W+  e+e, + (,+) or: W+  ud, us, cs t g g g t q t q t au Tevatron:10% 90% au LHC:90% 10% σLHC = 833 pb = 100σTeV Final states (classified according to W decays, excluding taus): • fully leptonic channel 5% 450000evts/year low bg • semi-leptonic channel 30% 2,700,000evts/year good sg/bg • fully hadronic channel 44% 4,000,000evts/year large bg QCD

  31. ttb+jjbin ATLAS muon Hadronic jets Missing energy Hadronic jet

  32. Reconstruct the W bosons – select (jj) minimizing |mjj – mW| – W purity: 66% – efficiency : ~80% Light jet calibration of W Energy calibration 1-2% Measurement of the top quark mass: semi-leptonic channel σ = 7.4 GeV Nbtag = 2

  33. Reconstruction of hadronic top quark top association of b jets with W boson: – largest pTtop – maximize ∆R(l,b) – minimize ∆R(b,Wjj)  purity top : 69%  efficiency : 1.2% Number of events ~30K (80K) events in 2 b-tag (≥1b-tag) physics background ~ 100 events ! resolution : σ≈ 11 GeV Measurement of the top quark mass: semi-leptonic channel σ = 10.6 GeV

  34. fully hadronic channel: 6 central jets (high pT) 2 b ~ 100,000 evts in 10 fb-1 combinations and selections: W jj (2W) t Wb (2t) 130 < |mjjb| < 200 pTtop ≥ 200 GeV/c resolution 13 GeV/c^2 S/B: 18/1 Measurement of the top quark mass • fully leptonic performance with 10 fb-1 • Evt/evt: mt solve system  weight • all evts: mean weight per m • mtfit = mt w/ highest <weight> • σ ≈ 13 GeV/c2

  35. Polarisation of the W boson in top decays: search for deviations from the standard model Decay t W+b 3 helicity states possible for a W boson: -1,0,+1 b W W t t t W b b  W Polarisation and the Wtb coupling lepton: sign and direction wrt W reco of decay angle possible (standard model: f1L = Vtb1 , f1R = f2L = f2R=0) Determine FL, F0, FR and translate to fiL,R

  36. mecanisms: The final standard model topic: single top production t channel s channel W+t channel NLO= 231± 9 pb NLO= 10.1 ± 0.7 pb LO= 60 ± 15 pb • Backgrounds: tt, W+jets, QCD-jets Clear signal

More Related