Victoria Martin Northwestern University La Thuile 2004

1. W and Z Physics at CDF Contents: Electroweak Physics at Run II CDF Detector and Reconstruction Cross Section Measurements Precision Measurements Conclusions and Outlook Victoria Martin Northwestern University La Thuile 2004

2. Why Electroweak Physics at Run II? • Large numbers of W bosons • High mass Z/γ* events • Sensitive to u & d quarks Di-boson cross sections Beyond SM: Di-bosons couplings Z’resonance anomalous q couplings Tri-boson couplings New Forward Detectors W, Z cross sections Z Forward-Backward Asymmetry W asymmetry sin2(θW), quark couplings Indirect Γ(W) Higgs Mass Constraint W mass Lepton Universality Direct Γ(W)

3. Run II Luminosity 200 pb−¹ 120 pb−¹ 72 pb−¹ • Tevatron has delivered ~430 pb−¹ • We have ~350pb−¹ on tape. • Analyses presented here are using either ~ 72 pb−¹, 120 pb−¹ or 200 pb−¹ of data • Error on luminosity is ±6%. Limited by knowledge of pp inelastic cross section.

4. CDF Run II Detector • From Run I: • Solenoid • Central muon system • Central calorimeter Polar angle θ • New For Run II: • Front-end DAQ • Trigger • Track (L1) and Displaced Track (L2) • Silicon Tracker (8 Layers) (η 2.0) • Central Outer Tracker (η 1.0) • Plug Calorimeters (1.0 η 3.6) • Extended Muon Coverage (η 1.5, gaps filled in)

5. CDF Run II Detector Central+Plug Calorimetery η 3.6 Muon Chambers η 1.5 Central tracking η 1.0 Silicon tracking η 2.0

6. Electron, Muon, Photon & Neutrino Reconstruction Plug electron: EM calorimeter cluster (silicon, COT hits may be attached) Electrons Neutrinos: Large Missing Energy (Only Transverse: ET) Central electron: A track pointing to an EM calorimeter cluster 1.0  η 2.8 η 1.0 η 1.0 ‘Tight’ Muon: An isolated track pointing to a muon ‘stub’ η 1.0 η 1.1 ‘Loose’ muon: An isolated track pointing to a gap in the muon coverage Photons: EM Calorimeter cluster with no associated track Muons

7. Inclusive W and Z Signals

8. Inclusive W cross section • W→μν signal: • tight muon plus large ET • W→eν signal: • central electron plus large ET • Backgrounds from QCD, Z→ℓ+ℓ−, W→τν and cosmic (μ channel)

9. Inclusive Z cross section • Z → e+ e− signal: • 2 central electrons (CC) • 1 central plus 1 plug electron (CP) • Z →μ+μ− signal: • one tight muon plus one track • 66 < m(ℓℓ)/GeVc-2 < 116 • Small backgrounds from QCD, Z/W→τ, cosmics (μ) less than 1.5% For 66 < m(ℓℓ)/GeVc-2 < 116:

10. W→τν and Z→τ+τ− Signals • Look for hadronic tau decays • Narrow isolated jet • Low track multiplicity • invariant mass of tracks and π0 < m(τ) • 2345 candidate events in 72pb-1 • Z→τ+τ− signal: • 1 hadronic tau decay (jet) • 1 τ→eν or τ→μν decay • Backgrounds from Z→l+l−, QCD

11. Combining e and μ channels • Assuming lepton universality, combine W and Z results • correlated systematics effects accounted for

12. BR(W→ℓν) and Γ(W) 3.3677±0.024 NNLO (PDG) From LEP: (3.366 ± 0.0002)% Using NNLO calculation Γ(W→ℓν)=226.4 ±0.4 MeV (PDG): Current World Average: 2092±42 MeV

13. Lepton Universality • Calculate R separately for e and μ channels: • From a measurement of yields from a τ trigger, we extract an value for the ration of τ and e couplings:

14. Z→e+e−Forward-Backward Asymmetry e+ θ e− P • Tevatron is uniquely sensitive to Z-γ* interference at high invariant masses. • Shape of the Afb spectrum can be used to extract values for sin2(θW) and u, d couplings to Z • Agreement with SM prediction. P angle between p and e−

15. Di-boson Signals W γ Z γ Triple Boson Coupling Non SM!

16. Di-boson production: Wγ • pp → Wγ→ ℓνγ • One tight high-PT lepton (e,μ) • One Photon with: • ET>7GeV • ΔR(γ,ℓ)>0.7 • Large missing-ET • Backgrounds from QCD, Zγ • Probes electroweak boson self-coupling, new physics ET(γ) ΔR(γ,ℓ) NLO prediction (U. Baur) (LO + ET(γ) dependent k –factors):

17. Di-boson production: Zγ • pp → Zγ→ ℓ+ℓ—γ • Two oppositely-charged high-pT leptons • One photon with ET>7GeV, ΔR(γ,ℓ) > 0.7 • Small backgrounds (~10%) NLO prediction (U. Bahr) (LO + ET(γ) dependent k –factors):

18. Di-boson production: W+W− • pp → W+W—→ ℓνℓℓ’νℓ’ • Two oppositely-charged high-pT leptons • Large missing-ET • Veto events with jets • Veto Z background: 76<mee, mμμ<106 GeV/c2 • 5 candidate events in 126pb-1 • (2.3±0.4) background expected from Drell-Yan, QCD, WZ and tt. NLO calculation:Campbell & Ellis hep-ph/9905386

19. Towards W Mass and Asymmetry Work in progress – no results yet • Use MC templates to fit to signal + background • CDF Run I mW = 80,465 ± 100(stat) ± 104(sys) MeV • CDF Run II for 500/pb (estimated): • = X ± 40(stat) ± 55(sys) MeV Sensitivity to u/d fraction PDFs High mT tail is sensitive to Γ(W)

20. Conclusions • We have measured the cross section for pp collisions at √s=1.96 TeV • W→ℓν for electron, muon, tau channels • Z→ℓℓ for electron and muon channel • Di-bosons: Wγ, Zγ, WW • Extracted first results on electroweak parameters: • Indirect measurement of Γ(W) • Lepton universality • All results consistent with Standard Model – no sign of New Physics (yet!) • Look for CDFII first results on W-mass, W asymmetry, direct Γ(W), sin2(θW) and boson-quark couplings, all coming soon!