Electroweak Results from DØ Bob Olivier LPNHE – Paris on behalf of the DØ collaboration W Mass Measurement W/Z production cross-sections W Width determination Trilinear Gauge Couplings QCD effects in W/Z production

W and Z in pp collisions QCD cross-section p dominates =>selection based on leptonic decays only l q q’ W,Z p l,nl W selection: isolated lepton (e,m,t): ET > 15 – 25 GeV neutrino(n): ET > 25 GeV Z selection: 2 isolated leptons (ee,mm) : ET > 15 – 25 GeV Looser criteria on 2nd lepton Data Samples: Run 1a: L~15 pb-1 Run 1b: L~90 pb-1 h < 1, 1.5 < h <2.5 electron channel W– candidates: 67078 Z – candidates: 5397 April 17-19, 2000 Bob Olivier - PHENO2000

Measurement of MW Radiative corrections DrW to MW depend on MH Consistency check of SM Measured Quantities: No longitudinal momentum conservation due to particles escaping in the beam pipe MW from fit to: April 17-19, 2000 Bob Olivier - PHENO2000

DØ: MW with e at large rapidity EC CC EC EC CC EC h(W) sensitive to pdf’s and correlated to h(e) Good agreement with MRST used for MC description Calibration from  adjusted to LEP value in CC-EC and EC-EC Z statistics is dominant error DMW = 181 MeV (EC) DMW = 59 MeV (CC+EC) April 17-19, 2000 Bob Olivier - PHENO2000

DØ: MW Results MT fit MW from fit to MT (W): Combined CC+EC: window pT (e) fit MW from fit to pT (e): Combined CC+EC: pT (n) fit MW from fit to pT (n): Combined CC+EC: Combined results from Run 1b: Combined results from Run 1a, 1b: April 17-19, 2000 Bob Olivier - PHENO2000

MW : World Average Good agreement hadronic & leptonic colliders World average precision on MW =38 MeV April 17-19, 2000 Bob Olivier - PHENO2000

Constraints on MHiggs CDF and DØ DMW = 63 MeV Constraints on MH from MW ~ Mtop April 17-19, 2000 Bob Olivier - PHENO2000

W,Z cross-sections for e,m,t decays Run 1c @ CDF and DØ use different for luminosity determination CDF: DL = 4.1% (CDF measurement only) DØ: DL = 4.4% (CDF, E710, E811)  Run 1c @ @ in good agreement with UA1/UA2 April 17-19, 2000 Bob Olivier - PHENO2000

Lepton Universality: t - e Ratio of from cross-section ratio:  Errors in luminosity cancel in ratio World average verifies e-t Universality at 2.5% April 17-19, 2000 Bob Olivier - PHENO2000

Branching Ratio B(W  en) measured Theory (± 1.5%) LEP (± 0.2%) extracted Branching Ratio at 2.5% from Tevatron April 17-19, 2000 Bob Olivier - PHENO2000

Indirect Determination of G(W) Theory (± 0.4%) measured Theory (± 1.5%) LEP (± 0.2%) extracted DØ : 95% C.L. on invisible W-width 0.191 GeV April 17-19, 2000 Bob Olivier - PHENO2000

Trilinear Gauge-Boson Couplings WW production WZ production Trilinear couplings: In SM: lZ = lg = 0 , kZ = kg = g1Z = g1g = 1  prevents unitarity violation at low scale Constrain trilinear gauge boson couplings: look for indications of new physics.  April 17-19, 2000 Bob Olivier - PHENO2000

WW/WZ in channel pt(W) spectrum sensitive to anomalous coupling (DkV for lV = 0) Fit to pt(en) and pt(mn) assuming equal WWg and WWZ couplings 95% CL at LFF =2 TeV mnjj: enjj: April 17-19, 2000 Bob Olivier - PHENO2000

WZ in tri-lepton channel WZ production is sensitive to WWZ coupling only, independent of WWg coupling Search in enee and mnee channels: 1 candidate event  SM prediction: 0.245 ± 0.015 events  Backgrounds: 0.50 ± 0.15 events Limits at 95% C.L. : |l| < 1.42, |D gZl | < 1.63 April 17-19, 2000 Bob Olivier - PHENO2000

Limits on TGC April 17-19, 2000 Bob Olivier - PHENO2000

W Angular Decay Distribution QCD corrections: W g q q’ q sq V-A V-A: q sq sW QCD V-A+QCD: QCD corrections prefered at ~2 s (Systematic errors 6-15%) April 17-19, 2000 Bob Olivier - PHENO2000

pt dependence of σ(Z) Sensitivity to gluon radiation in dσ(Z)/dpt pt>10 GeV: perturbative QCD pt<10 GeV: resummation techniques pt  0 : parametrization of non-perturbative effects NNLO-QCD calculation From RESBOS with CTQ4M pdf In good agreement with dσ(Z)/dpt DØ Low pt: fit of Sudakov form factor Ladinsky -Yuan form factor: g2=0.59 ± 0.06 GeV2 g1=0.09 ± 0.03 GeV2 g3=-1.1 ± 0.06 GeV-1 April 17-19, 2000 Bob Olivier - PHENO2000

Conclusions - Outlook SM in good agreement with high precision EW measurements Precision on MW better than 100 MeV Run2 prospectives: 15fb-1 from 2001 to LHC ~2fb-1 in first 2 years and improved detectors (tracking)  April 17-19, 2000 Bob Olivier - PHENO2000

Backup Slides April 17-19, 2000 Bob Olivier - PHENO2000

pt dependence of σ(Z) Sensitivity to gluon radiation in dσ(Z)/dpt pt>10 GeV: perturbative QCD pt<10 GeV: resummation techniques pt  0 : parametrization of non-perturbative effects  form factor High and medium pt range: NLO-QCD calculation + pT resummation from RESBOS with CTQ4M pdf DØ Data vs ResBos In good agreement with dσ(Z)/dpt April 17-19, 2000 Bob Olivier - PHENO2000

Extraction of non-perturbative parameters Low pt range: fit of Sudakov form factor from Ladinsky and Yuan most sensitive from low-energy Drell-Yan data and CDF Z event sample (1988-89) New extraction of g2 g2 = 0.59  0.06 GeV2 In good agreement and more precise than previous measurement D0 also extracts: g1 = 0.09  0.03 GeV2 g3 = -1.1  0.6 GeV-1 April 17-19, 2000 Bob Olivier - PHENO2000

Recent LEP limits on TGC April 17-19, 2000 Bob Olivier - PHENO2000