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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

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BSM at the LHC

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  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

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