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Electroweak Measurements at CDF

HPRN-CT-2002-00292. 1. Electroweak Measurements at CDF. A. Sidoti For the CDF Collaboration LPNHE- Universite Paris VI “Pierre et Marie Curie” (Paris, France). Lake Louise Winter Institute (Canada) February 20-26, 2005. Why Electroweak Measurements?. Precise Electroweak predictions

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Electroweak Measurements at CDF

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  1. HPRN-CT-2002-00292 1 Electroweak Measurements at CDF A. Sidoti For the CDF Collaboration LPNHE- Universite Paris VI “Pierre et Marie Curie” (Paris, France) Lake Louise Winter Institute (Canada) February 20-26, 2005

  2. Why Electroweak Measurements? • Precise Electroweak predictions • Challenge for Electroweak physics measurement • Constrains the Standard Model OR • Appearance of Physics Beyond SM • Also crucial as input for LHC physics program: • Input to Parton Distribution Functions • Some Tevatron signals will be LHC background • After LEP era stepping into Tevatron era: N(Z)@Tevatron > N(W)@LEP

  3. Rate @L=1032cm-2s-1 (-) s(pp→X) Tevatron s(pb) ~108 ~2700 ~250 ~20 ~10 ~4 ~6 (Hz) ~104 ~0.3 ~0.03 ~0.02 ~10-3 ~4.10-4 ~6.10-4 Evts/Week 6.109 ~2.105 ~2.104 ~103 600 240 360 SppS LHC 1mb bb W→ene Z→ee Wg→eng WW Zg→eng t t 1mb 1nb s(W→lvl) - _ 1pb 0.001 0.01 0.1 1.0 10 102 √s (TeV) Production Processes at Tevatron Yield ~104 Ws , ~103 Zs • Outline: • W and Z cross sections • Asymmetries (W and Z) • Diboson production • W mass measurement

  4. ET>25GeV W/Z Gauge Bosons and Event Topology At hadron colliders Use clean leptonic decays ET>25GeV W ±energetic lepton + ET Z energetic opposite sign leptons PTm>20GeV PTm>20GeV

  5. Inclusive W/Z Cross Sections s(pp→Z)xBF(Z→ll)Th,NNLO=251.3±5.0pb Good agreement with NNLO • Systematics limited measurement • Uncertainties: Luminosity (6%) PDFs(2%) s(pp→W)xBF(W→ln)Th,NNLO=2687±54pb

  6. .BF(W->lvl) R= CDF II(m) .BF(Z->l+l-) (pp->W) (W->ll) R = (pp->Z) (Z->ll) (W) G(W)(MeV) 2079±41 2056±44 2118±41 2092.1±2.5 ∫Ldt(pb-1) 72 194 Channel e+m m PDG SM Pred. Indirect W Width Measurements PDG Checking internal consistency of SM with direct G(W) measurement R: cross section measurement ratio: Many systematic uncertainties cancel out(Luminosity) Indirect W Width measurement

  7. W Asymmetry Sensitivity to PDF distributions(u/d ratio): u carries more momentum than d Observable quantity is lepton rapidity: Convolution of W asymmetry and V-A interactions Charge ID at high |h| is crucial: Use of calorimeter seeded tracks ∫Ldt=170pb-1 Asymmetry Asymmetry Larger ET: electron direction closer to W direction. Production asymmetry enhanced. Lower ET: decay asymmetry enhanced

  8. g p0 EM Calorimeter ET(g)>7 GeV DR(g,l)>0.7 |hg|<1.1 Cal & Trk Iso g Shower Maximun Detector g Pre-Shower Detector DiBoson Production Test Gauge Boson Self Interactions SM Higgs searches Resonance searches: Look for excess in kinematical distributions: ET(g) , 3body mass, lepton PT Complementarity with LEP experiments: Probing at higher √s W-g final state For Wg/Zg Photon Id is crucial: Main backgrounds: p0→gg, jets faking photon Fake Rates: 0.2% @JetET=10 GeV 0.05% JetET>25GeV

  9. l l   q q q' W W l W ? ISR FSR q' WW q BSM    q Events(e+m) Back(%) •B(Wl) (pb) sx BTh(pb) 18.1±1.6stat±2.4sys±1.2lum 19.3±1.4 195+128 35(e),33(m) Wg Production ET(g) Distribution ∫Ldt≈200 pb-1 Baur, Han, Ohnemus(1993,1998) CDF Run II

  10. Z-g Production

  11. Zg Kinematical Distributions 3Body Mass ET(g) Distribution BSM Predictions Dk=5 l=5 Dk=7 l=0 No significant excess with respect to SM expectations Dk=0 l=3 SM 0 5 10 15 20 25 30 35 40 ET(g)

  12. WW Production

  13. l Z q 76 < M(ll) < 106 GeV l ll : 76 < M(ll) < 106 GeV : large ET-significance l: lepton + ET > 20 GeV ll Z,W q(') l 4 Lep 0.06±0.01 0.01±0.02 0.07±0.02 0 3 Lep 0.91±0.07 0.07±0.06 0.98±0.09 0 2 Lep 1.34±0.21 0.94±0.22 2.28±0.35 3 Comb. 2.31±0.29 1.02±0.24 3.33±0.42 3 WZ/ZZ Bkg Bkg+Sig Data WZ and ZZ Searches Entangled Processes ∫Ldt = 194pb-1 s(pp→ZZ/ZW+X)NLO=5.0±0.4 pb-1 Extracted a limit for cross section Measurement possible with available collected statistics s(pp→ZZ/ZW+X)CDF<15.2 pb @95% C.L.

  14. CDF Run II Preliminary W Boson Mass Bound to SM Higgs Mass Indirect searches of physics BSM Need accuracy better than 10-3 Fit of transverse mass distribution G(W) direct measurement Result: With L=200pb-1DMW=76 MeV/c2 (e+m) combined →Already better than RunI CDF With 2fb-1 expect D(Mw)~30MeV/c2 Will use next PDFs fits with CDF W charge asymmetry measurement Top Mass(GeV/c2)

  15. Perspectives and Working Areas Electroweak physics program at CDF goes well • Inclusive cross section, widths, BF in all leptonic channels. Working on Differential Cross Sections • Z asymmetries Quark gauge bosons couplings • W asymmetries Shall be included in 2005 PDFs W Rapidity reconstruction • Diboson production cross section (increase statistics) Extracting Triple Gauge Coupling Looking for hadronic final states WW→(qq’)(lnl) • W Boson Mass Measurement: unveiling the central value Direct G(W) measurement

  16. O fortunati, quorum iam moenia surgunt! Verg., Aen., I 437 Electroweak RunII Publications hep-ex/0406078: “Inclusive W and Z Cross Section” hep-ex/0501023: “W Charge Asymmetry” hep-ex/0411059: “Z Forward Backward Asymmetry” hep-ex/0410008: “W gamma, Z gamma production” hep-ex/0501050: ”WW Production” hep-ex/0501021: “WZ/ZZ Searches”

  17. Backup Slides

  18. Central calorimeters Solenoid Central muon New Old Partially new Front end Trigger DAQ Offline TOF Endplug calorimeter Silicon and drift chamber trackers Forward muon The Run II CDF Detector

  19. Tevatron Performances and Perspectives

  20. Clean Signature • Two High ET Isolated lepton • Opposite Charge • High & S/B Events •B(Z-->ll) (pb) Back. Lum 4242 e 267±6stat±15sys±16lum 0.6% 72.0  3568 0.4% 253±4.2stat+8.3-6.4sys±15.2lum 193.5 Z Boson Cross Sections(e,) Muon Channel PTm>20 GeV/c Electron Channel Electron |h|<2.8 ET>25 GeV

  21. s(pp→W→ln)(nb) s(pp→Z→)(nb) 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 √s(TeV) 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 √s(TeV) 20 Years of W and Z at hadronic colliders NNLO NNLO

  22. W Boson Production Electron Channel Muon Channel •B(W-->en) (pb) Region Events Bkg 2786±16stat±64sys±166lum |h|<1.0 37584 4.4 72 e 2874±34stat±167sys±172lum 8.7 10464 1.1<|h|<2.8 64 m 194 57109 9.5 |h|<1.0 2786±12stat+65-55sys±172lum

  23. e  q q e+ Rosner, J.L.: Phys. Rev. D 54, 1078 (1996) ∫Ldt=72 pb-1 500 GeV/c2 Z’ Zx c2=15.7/15 Z Z Asymmetry AFB arises from Axial and Vector couplings Z and g interference term Measurement limited by statistics Complementary to LEP measurement far from the Z pole Sensitivity to heavy neutral bosons (Z') Extract quark, electron couplings and sin2qWEff

  24. CDF Run II 2 fb-1 Uncert. Experimental values (PDG) SM Prediction uL 0.41  0.14  0.028 0.330  0.016 0.3459 ± 0.0002 ur 0.02  0.15  0.024 -0.176  0.008 -0.1550 ± 0.0001 dL -0.12  0.39  0.057 -0.439  0.011 -0.4291 ± 0.0002 dr  0.088 -0.023  0.058 0.0776 ± 0.0001 -0.02  0.22 CDF Run II SLD+LEP SM prediction eV -0.058  0.017 -0.03816  0.00047 -0.03816  0.00047 eA -0.53  0.14 -0.50111  0.00035 -0.5064  0.0001 Couplings Results c2=10.40/11 Quark Couplings: sin2θWEff=0.2238±0.0040(stat)±0.0030(syst) c2=12.50/14 Electron Couplings: c2=13.14/13

  25. .BF(W->lvl) R= .BF(Z->ll) (pp->W) (W->ll) (pp->Z) (Z->ll) (W) 20+ years of W and Z bosons at hadron colliders From R to G(W) Indirect W Width measurement

  26. Tau Taus are difficult at hadronic colliders t→hadrons (th) look like jets Need to combine: Tracking (|h|<1) Calorimetric Clusters Dhx Df (0.1 x 15o) po reconstruction (showermax inside EM Calorimeter resol. ~few mm) Reconstruction Efficiency: ~70% @15 GeV ~85% @25 GeV ~95% @40 GeV It is possibile to trigger on taus: Lepton + Track trigger (lepton + isolated track). Final states:th+t(e,m)+X,th+(e,m)+X

  27. Tau Physics Measurement Track Multiplicity: 1 and 3 prongs Z->teth

  28.   Events(e+m) Back(%) •B(Wl) (pb) sx BTh(pb) 18.1±1.6stat±2.4sys±1.2lum 19.3±1.4 195+128 35(e),33(m) Wg Production q  l ISR CDF Run II W  q' l WW q' W q l q'  W FSR q ∫Ldt≈200 pb-1 Baur, Han Ohnemus(1993,1998)

  29. Rosner, J.L.: Phys. Rev. D 54, 1078 (1996) 500 GeV/c2 Z’ Zx Z Z Asymmetry CDF Run I (~110 pb-1)

  30. Calculating AFB • Calculating AFB: • cos* in Collin-Soper frame • Minimize ambiguity in the incoming quark Pt • cos*>0 Forward • cos*<0 Backward lab frame Z0/g* PZ =0 Z-Axis Z0/g*

  31. Data-MC Comparisons CDF II Preliminary

  32. Data-MC: Cos(*) CDF II Preliminary

  33. gVf 1.0 0.8 0.6 0.4 0.2 0 -0.2 -0.4 -0.6 -0.8 -1.0 c2=10.40/11 CDF Run II SLD+LEP SM prediction eV -0.058  0.017 -0.03816  0.00047 -0.03816  0.00047 eA -0.53  0.14 -0.50111  0.00035 -0.5064  0.0001 c2=13.14/13 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 gAF Couplings Results Electron Couplings: c2=13.14/13 Quark Couplings: sin2ΘWEffMeasurement: sin2θWEff=0.2238±0.0040(stat)±0.0030(syst) c2=12.50/14

  34. W Asymmetry Anastasiou, Dixon, Melnikov, Petriello, Phys Rev D 69, 094008 (2004) Charge ID is crucial at high rapidity

  35. Raw Asymmetry Shape is convolution ofA(yW) and V-A Sign switch @  > 2 • Corrections to extract true asymmetry: • Charge misidentification rate. • Background subtraction. • Both bias the asymmetry low → dilution. • Measured in each  bin. • Uncertainties in corrections go directly in A. < 1 ~ linear Curve is just to guide the eye.

  36. u d – d – u W Asymmetry xf(x,Q2) Run I Result log(x) • [http://durpdg.dur.ac.uk/hepdata/pdf3.html]

  37. Phoenix (Calorimeter-Seeded) Tracking Two points and a curvature define a helix: • Primary collision vertex position. • Fitted position of calorimeter shower maximum. Use both central and forward electrons! |h| < 2.8 Zoom into Silicon: Phoenix SiTrack Cal. Seed Tracks

  38. jet fake rate 0.2% 0.06% cluster transverse mass : Wg production

  39. LO MC Inteference between ISR and TGZ gives radiation zero (RAZ) Q(hg-hl) RAZ Wg DR(g-l)

  40. Z-g

  41. CDF Run II l  q Z0 l  q Non SM process! l  q  Z0 l  q Events(e+m) Back(%) s(Zg)•B(Z→ll) (pb) sx B(Th)(pb) 4.5±0.3 36+35 7.8e,5.8m 4.6±0.5stat+sys±0.3lum Zg Production

  42. W W Z,g* Interesting Signal Background in SM Higgs searches Probe for new physics W W Z’,G H +5.8 -5.1 +1.8 -3.0 s(WW)=14.6 (stat) (syst)±0.9(lum) pb 17 candidate events Estimated Bkg 5.0+2.2-0.8 ∫Ldt=184 pb-1 Looking for WW→(qq’) (lnl) final states s(pp→WW)NLO=11.3±1.3pb WW production

  43. WW->en+mnm

  44. WW->en+mnm or ZZ->ee nn?

  45. W Boson Mass background

  46. W Boson Mass

  47. WW production: Kinematical Distributions Lepton PT Dilepton Invariant Mass No significant excess so far

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