Electroweak and Related Physics at CDF Tim Nelson Fermilab on behalf of the CDF Collaboration DIS 2003 St. Petersburg April 2003

T. Nelson, DIS Slide 2 Outline Experimental Status Electroweak Top Precision Searches Outlook

T. Nelson, DIS Slide 3 Upgrades: E CM : 1.8  1.96 TeV E CM : 1.8  1.96 TeV Luminosity:  Luminosity:  Run 2b (396 ns) Run 2b (396 ns) Making progress… Currently less data approved for analysis than Run I 72 pb pb pb -1 w/ silicon 57 pb -1 w/ silicon Tevatron Status Luminosity [particles/cm 2 /s] Run 1b Current 2a Goal Run 2b

T. Nelson, DIS Slide 4 The CDF-II Detector Silicon Tracking Detectors Central Drift Chamber Solenoid Coil /TOF EM Calorimeter Hadronic Calorimeter Muon Drift Chambers Muon Scintillator Counters Major Upgrade: New Silicon Tracking New Silicon Tracking Extended coverage 3-D reconstruction New Drift Chamber New Drift Chamber Faster (2  s  396 ns) dE/dx 96 dE/dx samples/track New Forward Calorimeter New Forward Calorimeter 1.3 <|  |<3.5, same technology as central Added Time-Of-Flight Added Time-Of-Flight ~ 100 ps resolution Extended muon coverage Extended muon coverage |  | < 1  |  |<1.5 New Trigger New Trigger Tracks at L1 (p T >1.5 GeV/c) Silicon Tracks at L2 (p T >2.0 GeV/c)

T. Nelson, DIS Slide 5 Tracking Upgrades Tracking is fundamental to lepton identification   = - ln ( tan (  /2)) “central”:|  | < 1.1 “forward”: |  | > 1.1

T. Nelson, DIS Slide 6 Silicon Upgrade SVX Layer 00 SVXII ISL Run I Run 2a Silicon tracking is fundamental to tagging b -jets  = - ln ( tan (  /2)) tt  e+jets

T. Nelson, DIS Slide 7 Precision Electroweak (2 fb -1 ) Must walk before we can run!

T. Nelson, DIS Slide 8  W  B ( W  e ) Selections : ( acc   = 19.3% ) Electron (central only) – Isolated EM Calorimeter cluster – E T > 25 GeV – Matched track, P T > 10 GeV Missing E T > 25 GeV Sample : ( 72 pb -1 Run II) events – QCD: 3.5% – W   : 2.0% – Z  ee : 0.9%  W  B = 2.64  0.01 stat  0.09 sys  0.16 lum nb

T. Nelson, DIS Slide 9  W  B ( W   ) Selections : ( acc   = 10.1% ) Muon (central only) – Muon hits – Matched track, P T > 20 GeV – Min. Ionization in calorimeter Missing E T > 20 GeV Cosmic & Z   vetos Sample : ( 72 pb -1 Run II) events – Z   : 5.3% – W   : 3.2% – Cosmics: 1.3% – QCD: 1.0%  W  B = 2.64  0.02 stat  0.12 sys  0.16 lum nb

T. Nelson, DIS Slide 10  W  B ( W   ) Selections : ( acc   = 0.92% ) Tau (central only) – Isolated Hadronic Calorimeter cluster – P T & number of tracks in 10  /30  cones – E T > 25 GeV Missing E T > 25 GeV Dijet veto Sample : ( 72 pb -1 Run II) 2345 events – QCD: 15% – W  e : 4.4% – W   : 3.9% – Cosmics: 1.5% – Z   : 0.9%  W  B = 2.62  0.07 stat  0.21 sys  0.16 lum nb

T. Nelson, DIS Slide 11  Z  B ( Z  ee ) Selections : ( acc   = 9.5% ) 2 Electrons (central only) – Isolated EM Calorimeter clusters – E T > 25 GeV – Opp-sign matched tracks, P T > 10 GeV 66 < M ee < 116 GeV Sample : ( 72 pb -1 Run II) 1830 opposite-sign events – QCD: 0.5% – Z   : 0.05%  Z  B = 267  6 stat  15 sys  16 lum pb

T. Nelson, DIS Slide 12  Z  B ( Z   ) Selections : ( acc   = 9.2% ) 2 Muons (central only) – At least one with muon hits – Opp-sign matched tracks, P T > 20 GeV – Min. Ionization in calorimeter Cosmic veto 66 < M ee < 116 GeV Sample : ( 72 pb -1 Run II ) 1631 opposite-sign events – Cosmics: 0.8% – QCD:< 0.2%  Z  B = 246  6 stat  12 sys  15 lum pb

T. Nelson, DIS Slide 13 Clear Z   e  h signal Background needs further study Goal of preliminary cross section by summer Z   

T. Nelson, DIS Slide 14  W,  Z Summary combined  W  B ( W  l ) = ± stat ± syst ± lum nb combined  Z  B ( Z  ll ) = ± 4.3 stat ± 10.6 syst ± 15.1 lum pb

T. Nelson, DIS Slide 15  W   B ( W  e,  ) Selections : Electron or Muon (central only) + Missing E T – Same selections as used for  W 1 Photon (central only) – E T > 7 GeV,  R ( ,l ) > 0.7 * – Isolated EM calorimeter cluster – Tracking isolation cuts Z  ll & Cosmic(  ) vetos Sample : ( 72 pb -1 Run II) 43 (38) events in e (  ) – W  e (  ) + jet : 11.5 (5.6) events – Z  ee (  ) +  : 2.4 (5.1) events – W   +  : 0.5 (0.7) events  W  ( W  e ) * = 17.2  3.8 stat  2.8 sys  1.0 lum pb  W  ( W   )* = 19.5  4.5 stat  2.4 sys  1.2 lum pb SM Expected: ~19 pb e+ 

T. Nelson, DIS Slide 16  Z   B ( Z  ee,  ) Selections : 2 Electrons or Muons (central only) – Same selections as used for  Z M ll > 40 GeV 1 Photon (central only) – E T > 7 GeV,  R ( ,l ) > 0.7 * – Isolated EM calorimeter cluster – Tracking isolation cuts Z  ll & Cosmic(  ) vetos Sample : ( 72 pb -1 Run II) 11 (14) opposite-sign ee (  ) events – Z  ee (  ) + jet : 0.5 (0.5) events  Z   B ( Z  ee )* = 5.5  1.7 stat  0.6 sys  0.3 lum pb  Z   B ( Z   )* = 6.0  1.6 stat  0.7 sys  0.4 lum pb SM Expected: ~5 pb e+ 

T. Nelson, DIS Slide 17 Adding Forward Acceptance QCD backgrounds are many times larger without tracking requirements Tracking is critical Have standalone silicon tracking in forward region: much less efficient and clean than central drift chamber + silicon Need a way to reduce the problem!

T. Nelson, DIS Slide 18 Calorimeter-seeded e  tracking Two points and a curvature define a unique helix… Primary vertex – x-y : beamspot (~40 um) – z: event vertex (~100 um) Calorimeter shower-maximum hit – ~1 mm Calorimeter E T  |curvature| seed tracks Silicon hits Silicon Track

T. Nelson, DIS Slide 19 Forward W  e Selections : Electron (forward only) – Isolated EM Calorimeter cluster – E T > 20 GeV – Calorimeter-seeded track Missing E T > 25 GeV Sample : ( 60 pb -1 Run 2 data) ~20,000 events QCD background : without forward tracking: ~18% with forward tracking: ~3% Similar to central background

T. Nelson, DIS Slide 20 W  e Charge Asymmetry x = p (parton)/ p (proton) pdf(x) u d Forward tracking is critical here!

T. Nelson, DIS Slide 21 W  e Charge Asymmetry Selections : Electron (central+forward) – Isolated EM Calorimeter cluster – E T > 20 GeV – Calorimeter-seeded track Missing E T > 30 GeV Sample : events Blind analysis: Plotting sensitivity only Higher “specific sensitivity” in forward region than Run 1 results to be unblinded for summer CTEQ-3M - MRS-R2

T. Nelson, DIS Slide 22 Selections : 2 Electrons / Muons (central only) – Same cuts as EWK measurements Veto 76 < M ll < 106 GeV, cosmics & conversions Missing E T > 25 GeV   ( missing E T, nearest lepton ) N jets = 0 ( E t > 10 GeV,  < 2.0) Sample : ( 72 pb -1 Run II) 2 events – Background: 1.5  0.6 events ( QCD + DY + WZ + tt ) SM Expected: 2.8  0.6  WW ( WW  ll ) just the appetizer…

T. Nelson, DIS Slide 23  tt ( tt  ll ) Selections : 2 Electrons / Muons (central only) – Same cuts as EWK measurements Veto 76 < M ll < 106 GeV, cosmics & conversions Missing E T > 25 GeV   ( missing E T, nearest lepton ) H T =  E T + Missing E T > 200 GeV N jets  2 ( E t > 10 GeV,  < 2.0) Sample : ( 72 pb -1 Run II) 5 events – Background: 0.30  0.12 events ( DY + WW/WZ +  + QCD )  tt =13.2  5.9 stat  1.5 sys pb

T. Nelson, DIS Slide 24  tt ( tt  l+jets ) Selections : Electron / Muon (central only) – Same cuts as EWK measurements Veto 76 < M ll < 106 GeV, cosmics and conversions Missing E T > 20 GeV N jets  3 (jet E T > 15 GeV) At least one jet with secondary vertex tag from silicon Sample : (57.5 pb -1 Run 2 data) 15 events – Background: 3.8  0.5 events (W+jets & mistags dominant)  tt = 5.3 ± 1.9 stat ± 0.8 syst pb signal region control region

T. Nelson, DIS Slide 25  tt Summary Run II

T. Nelson, DIS Slide 26 M t ( l+jets ) signal background

T. Nelson, DIS Slide 27 Electroweak-related Searches A Challenging Goal : Model-independent, “signature-based” searches Focus on Final States : Many possibilities for new physics Very simple Backgrounds are “precision physics” “Precision Searches” Electroweak final states are ideal here…

T. Nelson, DIS Slide 28 Z, extra dimensions, compositeness High-mass e + e - ? ? central-central + central-forward (see A. Munar’s talk)

T. Nelson, DIS Slide 29 Angular Distributions: Interference p p  e+e+ e-e- Forward Backward cos 2  cos  ? ? central-central + central-forward

T. Nelson, DIS Slide 30 Forward di-electrons Selections : Electrons (forward only) – Isolated EM Calorimeter cluster – E T > 15 GeV – Calorimeter-seeded track Sample : ( 60 pb -1 Run 2 data) 843 events QCD background ( M ee > 100 GeV): w/o tracking: 60  5 stat % with tracking:4  3 stat % Similar to central-central background

T. Nelson, DIS Slide 31 Outlook Goal: pb -1 delivered in FY03 Store Number Total Luminosity ( pb -1 ) Delivered To Tape CDF efficiency continues to improve, as well

T. Nelson, DIS Slide 32 Conclusions Preliminary results established for major electroweak benchmarks Broad top physics program is underway Promising searches in clean electroweak final states now match Run I sensitivity Improved detector, new techniques will extend reach beyond expected luminosity increases