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Fisica del W e Z al Tevatron

Fisica del W e Z al Tevatron. Antonio Sidoti University of Pisa and INFN IFAE Torino 14 Aprile 2004. Outline: Tevatron: CDF and D  detectors Baseline Electroweak Measurements Electroweak precision measurements Towards W Mass measurements. Tevatron. Booster Recycler. CDF. D Ø.

uriel-oneil
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Fisica del W e Z al Tevatron

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  1. Fisica del W e Z al Tevatron Antonio Sidoti University of Pisa and INFN IFAE Torino 14 Aprile 2004 • Outline: • Tevatron: CDF and D detectors • Baseline Electroweak Measurements • Electroweak precision measurements • Towards W Mass measurements

  2. Tevatron Booster Recycler CDF DØ Main Injector Fermilab Tevatron Upgrade RunII s RunI = 1.8 TeV Now s RunII = 1.96 TeV • New Main Injector: • Improve p-bar production • Recycler ring: • accumulate p-bars • Commissioning

  3. Tevatron: Luminosity Integrated Luminosity is the key for Tevatron RunII success. Analysis presented here are based on different integrated luminosity period Record Peak Luminosity (05/02/2004) 6.11031 cm-2 s-1 CDF Takes data at >85% Silicon integrated most of runs CDF and DØ are collecting 1pb-1/day

  4. Tevatron: Luminosity

  5. DØ RunII Detector • Many improvements from RunI: • Solenoid installed for RunII (2T 60cmx2.8m ) • ->New Tracking system • Trigger + Electronics and DAQ Si Tracker: Layers&Disks 8 Layers Fiber Tracker Preshower

  6. CDF RunII Detector • From RunI: • Solenoid • Muon system • Central Calorimeter Polar angle q • For RunII: • Front-end DAQ • Trigger • Track (L1) and Displaced Track (L2) • New Silicon Tracker (8 Layers) (|h|<2) • Central Outer Tracker • TOF • Plug Calorimeters • Extended Muon Coverage Lepton Id up to |h|~2

  7. Electron: EM Calorimeters High Pt Track Muons: Muon Detectors High PT Track Neutrinos: Large Missing Energy Only Transverse ( Met) e/ p q Z(W) p q e/ () Z Signature: Two Isolated Leptons (opposite charge) W Signature: Isolated Lepton and MET Lepton ID At hadronic collider W and Z bosons: decaying hadronically are overwhelmed by QCD background -> identification trough leptonic decays

  8. W Cross Sections Central Electron channel (|h|<1.1) Muon channel (|h|<1.0) Extended pseudorapidity electron coverage+Forward Tracking 1.1<|h|Ele<2.8 Small background contamination (QCD, Wtn,Z ee) (~6% e, ~11 % m) Systematics from PDF, energy scales, material description

  9. W Cross Sections W One isolated muon with Pt>20 GeV/c |h|<1.6 ET>20 GeV 8305 Candidate ~12 % background contamination (mainly W, Z) We One isolated electron with Et>25 GeV |h|<1.1 ET>25 GeV 27370 Candidates

  10. Bosons decaying to Tau Both CDF and D in RunII can identify taus. CDF has a specific trigger identifying tau decaying hadronically conbining calorimetry and tracking. • Tau reconstruction@CDF: • Count tracks in 10ot-cone and veto tracks in 30o isolation cone • Reconstruct p0candidates in Shower Max detector • Combined mass < m(t) Wtt: 2345in ~72 pb-1 Background ~26 % (dominated by QCD)

  11. Uncertainties Central Value W cross section measurements CDF and DØ s(pp W)BF(Wlnl) Measurements(pb) Theory (Stirling NNLO): 2731  10 pb

  12. h(1st e)  1.0 h(2nd e)  2.8 Z Boson Cross Section Z-> ee Invariant mass distribution Z->mm Invariant Mass Distributions Central Central (CC) + Central Plug (CP) Extended coverage in the forwardh 2.8 • Small backgrounds : • QCD, Z/Wt, cosmics (μ) < 1.5%

  13. Z Boson Cross Sections • QCD Bkg contamination ~2.3% • 1139 candidates after bkg substraction ſLdt=42 pb-1 Z Boson PT reconstructed from Zmm candidates Zee candidates Zmm candidates QCD Bkg Contamination <1%

  14. Z Z  th+tℓ−: first look ! One t decays in hadrons, the other decays in leptons Main Background from QCD Taus from Z and W are a starting point: Will use them for SUSY searches, top physics, etc…

  15. Uncertainties Central Value Z Cross Sections Measurements CDF and DØ s(pp Z)BF(Zll) Measurements (pb) Mass Range 66 GeV/c2 < Mll<116 GeV/c2 Theory (Stirling NNLO): 252  9 pb

  16. W and Z Cross Section CDF Run II Electron 1.1<|h|<2.8 20 years of W and Z at hadronic colliders!

  17. Theory 10.66 0.05 From R to W width Measurement Measuring Ratio R of s x BF From Theory: Rosner et al. From LEP G(W) can be extracted indirectely. From Theory: Van Neerven R Measurements: DØ CDF R e-channel: R m-channel: R Combined G(W)(MeV) 10.860.18 0.16 11.100.27 0.17 10.940.150.13 2071 40 10.340.59 11.320.76 2187128 2092 ± 40 World Average 2150 ± 90 LEP Direct

  18. gt/ge CDF measurement 0.990.040.07 Lepton Universality From W decaying in e and m: gm/ge CDF measurement World Average 1.0110.018 0.9930.025 From W decaying in t:

  19. Z Forward Backward Asymmetry SM Contributions Beyond SM(Z’,New Interactions) • Probing (Unique at Tevatron): • Z/g* Interference in High Invariant Mass Region (far from Z-pole) Consistent with SM Constraints on non-SM Z Couplings soon!

  20. DiBoson Production • DiBoson Coupling Measurements: • Probe ewk boson self-coupling • Sensitivity to physics BSM(Anomalous Couplings) Z gamma W gamma Triple Boson coupling Non SM!

  21. Non SM DiBoson Production W-g Z-g

  22. Events Back •B(Wl) (pb) e+m 259 29% 19.7±1.7stat±2.0sys±1.1lum SM @s=1.96TeV 19.3 ± 1.4 W-gamma • Selection Cuts • One High-PT lepton(e,m) • One Photon(DR(g,l)>0.7) • Large Missing ET probing anomalous couplings ET(g) Consistent with SM

  23. Process: pp->Wg->lnlg Events Back •B(Wl) (pb) Ldt 16211 825 e 146 12% 17.8±3.6stat±5.3sys±1.1lum m 77 17% 22.0±4.2stat±7.3sys±1.4lum e+m 223 13% 19.3±4.2stat±5.2sys±1.2lum SM @s=1.96TeV 16.4 ± 0.4 W-gamma • One High-PT lepton(e,m) • One Photon(DR(g,l)>0.7) • Large Missing ET(ET>8 GeV) Consistent with SM

  24. Process: pp->Zg->llg Events Back. •B(Z-->ll) (pb) 69 6.8% 5.5±1.7stat±0.6sys±0.3lum Z-gamma • Two High-PT Leptons(Opposite sign) • One Photon (DR(l,g) >0.7) e+m Consistent with SM •B(Z-->ll)SM= 5.4 ± 0.3pb

  25. WW Production • Sensitive to WWγ and WWZ vertex • Higgs discovery channel • Right place to look for new Physics Ldt=200pb-1 sBR(WWℓ+ℓ- nn)Th = 12.50.8pb(NLO) Two complementary approaches: Dilepton selection (l+l-) (small yield and background) Tight Lepton + Isolated Track selection (larger yield and background) 14.3 +5.6 –4.9 (stat)  1.6(sys) 0.9(lum)pb 19.1  5.0(stat)  3.6(sys) 1.1(lum)pb Consistent with SM

  26. W Mass measurement: RunI The Tevatron Run 1 combined W mass measurement was ready six years after end of RunI • Method: fit Transverse Mass distributions to MC varying MW,including: • detectors effects, • W decay • W production model • In Run I larger uncertainties coming from: • Statistics • Detector Energy response • W Transverse Momentum • PDF (correlated between experiments)

  27. Run I Tevatron New Run I Top Mass Combined Measurement W Mass measurement: RunI W Boson mass SM key parameter and for SM Higgs mass constraints

  28. Tevatron Run II Predictions W Mass measurement: Run II Prospects direct extraction ofG(W) • Almost all systematic uncertainties will decrease with statistics(control samples) • Goal for Run II (with 250 pb-1) • CDF Run II estimate (μ): = X±55(stat)±80(sys) MeV/c2 • We need to improve uncertainties: • Radiative corrections (electrons) • QCD effects in W/Z production

  29. Conclusions CDF and DØ Detectors are taking data Baseline EWK Measurements well established Analyzing twice the integrated luminosity of Run I Run II Expectations • Goals for Summer 2004: • ~500 pb-1 integrated luminosity per experiment. • Measuring: • Differential cross sections • W Mass, Direct G(W) • Constraints on TGC and Physics Beyond SM

  30. 0  CDF Et ()>7 GeV DØ Et ()>8 GeV R(,l)>0.7 GeV |  |<1.1 Cal & trk-iso  Shower Maximum Detector Pre-shower Detector Photons at CDF

  31. CDF: WW (III)

  32. CDF: WW Beyond SM ggHWW 140<MH<180GeV/c2 Anoumalous TGC WWZ/WW

  33. CDF: WW e candidate

  34. Source W Statistics Lepton Scale Lepton Resolution PT(W) Recoil Model Selection Bias Bkg CDF m 100 85 20 20 35 18 25 CDF e 65 75 25 25 37 - 5 DØ e 60 56 19 15 35 12 9 Source PDF and Parton Luminosity Radiative Corrections G(W) CDF 15 11 10 DØ 74 12 10 W Mass measurement: RunI Systematics Uncorrelated Uncertainties (MeV/c2) for W boson mass Correlated Uncertainties (MeV/c2) for W bson mass

  35. COT aging issues • Drift chamber aging: • Decline in operating performances with time • Loss of gains • Caused by organic deposits on wires • Investigating the causes… • Aging is detected: • Less charge collected, shorter pulse widths • Decrease of COT hit widths, smaller COT efficiency (impacts trigger XFT as well) • Smaller event yields(D0Kp down 36%) • Worse PT resolution(D0Kp invariant mass resolution (15 20 MeV/c2) References: http://www-cdf.fnal.gov/internal/upgrades/cot/cot_aging.html

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