W properties AT CDF J. E. Garcia INFN Pisa

Outline Corfu Summer Institute Corfu Summer Institute September 10 th 2 1.CDF detector 2.W cross section measurements 3.W mass and width 4.W charge asymmetry 5.Summary Jose E. Garcia – INFN Pisa

Tevatron Corfu Summer Institute Corfu Summer Institute September 10 th 3 Precise Electroweak measurements Check Standard Model Provide evidence of physics beyond SM Important input to LHC physics program Tevatron is for the next years the only accelerator than can produce Ws directly: ~ 90,000 W  e (  ) events per week. With a week luminosity of 15 pb -1.

Forward ElectroMagnetic and Hadronic calorimeters (“PLUG”). (1 < |  | < 3) Drift chamber (COT) Drift chamber (COT) Corfu Summer Institute Corfu Summer Institute September 10 th 4 CDF II Silicon tracker Silicon tracker a. L00 (1 SS, r-  ) b. SVXII (5 DS) c. ISL (2 DS |  | > 1, 1 DS |  | 1, 1 DS |  | < 1) Muon Systems Muon Systems

W Production W decay signatures (lepton channels): Isolated, high p T lepton with large missing transverse momentum Muon channel Corfu Summer Institute Corfu Summer Institute September 10 th 5 Electron channel

Corfu Summer Institute Corfu Summer Institute September 10 th 6 W Production

M T (GeV/c 2 ) Corfu Summer Institute Corfu Summer Institute September 10 th 7 W Cross Section in Plug Candidate events 64 pb -1 Estimated background Acceptance  efficiency 10,461(8.7± 2.4) %(5.2 ± 0.2) %   BR(W  e ) =  stat  sys  lum nb Update of the this measurement is in progress: Larger statistics ( ~ 220 pb -1 ) Much improved tracking efficiency Start re-blessing process this September Candidate events 220 pb -1 Estimated background Acceptance  efficiency 61, %8.7 % Preliminary

2874 W Cross Section Corfu Summer Institute Corfu Summer Institute September 10 th 8 Overall good agreement with the NNLO calculations Accuracy limited by the systematic effects Uncertainties dominated by luminosity measurements (~6%) Other systematics dominated by PDF uncertainties (~2%)

Lepton Universality Corfu Summer Institute Corfu Summer Institute September 10 th 9 W  e W  μ From the measurements of the W  e and W  μ cross sections obtain cross section ratio U: Many systematic uncertainties cancel out W  e W  τ In the same way from W  e and W  τ cross sections:

W Indirect Width Corfu Summer Institute Corfu Summer Institute September 10 th 10 CDF II (e+  ) CDF II (  ) R: cross section ratio measurement: Many systematic uncertainties cancel out (e.g. luminosity) Allows for an internal consistency check of the Standard Model with direct Γ(W) measurement Channel  (W)(MeV) e+  (72 pb -1 ) 2079 ± 41  (194 pb -1 ) 2056 ± 44 World Average2118 ± 44 SM Prediction2094 ± 3 PRL94, (2005)

W Mass Measurement Corfu Summer Institute Corfu Summer Institute September 10 th 11 Tevatron Run II has now 6 times Run I CDF, DØ data sets. CDF has analyzed first 200 pb -1 of data and determined uncertainties. Run II goal is to reduce uncertainty to less than 40 MeV. LEP:80,447  42 MeV Tevatron:80,454  59 MeV (Run I) ΔM W = 34 MeV Precise knowledge of M W constrains SM M H, as well as hypothetical new particles. W propagator includes H, tb and hypothetical new particle loops.

W mass is obtained from transverse mass (M T ) W Mass Measurement Corfu Summer Institute Corfu Summer Institute September 10 th 12 Detector Calibration Calorimeter energy scale Tracking momentum scale Simulation NLO event generator Model detector effects DATA W Mass templates + Backgrounds Binned likelihood fit W Mass

Z events are used for tuning and cross-checks  model recoil energy and to calibrate the lepton resolution W Mass Measurement Corfu Summer Institute Corfu Summer Institute September 10 th 13 CDF RUN II PRELIMINARY Muon momentum scale is determined to 3 parts in 10,000 using J /  and  (1s) decays. Use calibrated tracks to set calorimeter electromagnetic energy scale: E/p peak in W events. CDF RUN II PRELIMINARY

W Mass Measurement Corfu Summer Institute Corfu Summer Institute September 10 th 14 CDF RUN II PRELIMINARY m T fit m T (μν)(GeV) CDF RUN II PRELIMINARY m T fit m T (eν)(GeV) Using 200 pb -1 of Run II data CDF estimated the uncertainty on M W Total uncertainty: 76 MeV (e+  combined) already lower than CDF Run I (79 MeV)

In the collision u quark inside proton carries higher fraction of momentum than d. W production is sensitive to u(x)/d(x). W Charge Asymmetry Corfu Summer Institute Corfu Summer Institute September 10 th 15 Use Ws to probe the proton structure Observable quantity is electron rapidity Convolution of W production asymmetry and V-A decay

W Charge Asymmetry Corfu Summer Institute Corfu Summer Institute September 10 th 16 PRD71, (2005) Identification of the lepton charge is the key Probability of missId is around ~4% at |  | ~2

Summary Corfu Summer Institute Corfu Summer Institute September 10 th 17 Jose E. Garcia – INFN Pisa  RUN II CDF measurements are already better than results obtained in RUN I.  W mass has increased precision, expected to reach next year up to 30 MeV with 2 fb -1  W charge asymmetry has been included in PDF’05 fits  Direct W width measurement using Run II data  Results consistent with SM

Backup Slides W properties AT CDF J. E. Garcia INFN Pisa

Electrons EM Calorimeters High P T Track W/Z Identification Corfu Summer Institute Corfu Summer Institute September 10 th 19 At hadronic colliders W and Z bosons decaying hadronically are overwhelmed by QCD background.  Identification trough leptonic decays Isolated Lepton and E T W Signature: Isolated Lepton and E T Two Isolated Leptons (opposite charge) Z Signature: Two Isolated Leptons (opposite charge) Muons Muon Detectors High P T Track Neutrinos Large Missing Energy Only Transverse (E T )

Physics with W’s Corfu Summer Institute Corfu Summer Institute September 10 th 20  W boson identification is fundamental for many High-P T processes:  W properties  top searches ( tt  WW bb)  SM Higgs searches  precision measurements sensitive to New Physics.  It is a well known process, so it helps to set the basis for:  Understanding of the detector  Understanding of the backgrounds  Lepton identification (e, ,  )

Candidate events in 64 pb -1 Estimated background Acceptance  efficiency W  e 10,461(8.7± 2.4) %(5.2 ± 0.2) % W  e Cross Section in Plug Corfu Summer Institute Corfu Summer Institute September 10 th 21 M T (GeV/c 2 ) E T (GeV/c 2 ) Major systematics : PDFs, Amount of material in the simulation, Plug ET scale, Recoil modeling  QCD  Z  ℓ + ℓ −  W  

W  e Cross Section Corfu Summer Institute Corfu Summer Institute September 10 th 22   BR(W  e ) =  stat  sys  lum nb Working on an update of the measurement Bigger statistics ( ~ 220 pb -1 ) Much improved tracking efficiency 64 pb -1 sample For comparison: CDF - e (|  | < 1.1)   0.167(based on 72 pb-1) CDF -  (|  | < 1.1)   (based on 72 pb-1)

W Identification in Plug Region Plug region Plug region (1.1 > |  | > 2.8) E T > 20 GeV E T > 20 GeV (Electron energy corrected by offline corrections, Z vertex position and Ppr) Had/Em < 0.05 Isolation < 0.1 Isolation < 0.1 (Isorel corrected for leakage) Missing E T > 20 GeV Missing E T > 20 GeV (corrected for Zvertex) Electron track matches a calorimetric cluster ( No PHOENIX electrons). Match a track (P T > 1 GeV) such that track extrapolation to PES plane is within a 3 cm window of PES cluster (|Track X,Y – PES X,Y | < 3cm). |Track Z 0 | < 60 cm E/p < 2 Electron selection requirements as in the W plug cross section (blessed 18/03/04). Corfu Summer Institute Corfu Summer Institute September 10 th 23