1. Electroweak and Top Physics at the Tevatron
DIS2000, Liverpool
Frédéric Machefert
LPNHE-Paris
on behalf of the CDF and DØ collaborations
Electroweak measurements :
W/Z production at the Tevatron
W/Z cross-section
W width and mass measurements
Top quark :
Cross-section results
Mass measurements
Top properties
What is expected from Run II ?

2. W / Z production at the Tevatron
Main contribution from
QCD cross-section
(quark annihilation) p
2 leptons or
2 quarks p
Selection on the leptonic decays only
Z boson :
Require 2 leptons (ee or mm) : Et > GeV
Loose id-cuts for 2nd lepton
W boson :
One isolated lepton (e,m or t) : Et > GeV
Neutrino : Et > 25 GeV
Electron channel (Run I, L ~ 110 pb-1) :
CDF DØ
Z candidates
W candidates

3. W / Z cross-section Measurement of : swB(Wln) l=e, m, t szB(Z ll)
Dominant uncertainties come from
Luminosity
Parton Distribution Functions
L determined by s(pp)
measurements
CDF : DL=4.1%
(their own meas.)
DØ : DL=4.4%
(CDF, E710, E811 meas.)
L Rel. Diff. of 6.2%
1.062s(DØ)  s(CDF)
DØ result at
s=630 GeV

4. Partial width from Tevatron
BR(W  en)
Luminosity error
vanish
From theory :
LEP
measurement of
Partial width from Tevatron

5. Indirect GW measurement
G(Wen) from theory :
measured

6. MW measurement Drw : Radiative corrections MW direct measurement :
constraint on MH
test of the Standard Model
At Tevatron : PZ(n) unknown  cannot Measure MW
Measure Pt(l) and Mt p p W
MT sensitive to Et
Pt(l) sensitive to Pt(W) l n
Main systematic : lepton energy scale

7. Energy Calibration : CDF
Calibration with Zee and Zmm adjusted to Z mass value
Energy scale
m momentum linearity
low mass resonance :, J/
e energy linearity : E/p
E/p ~5 % below expectation
(track simulation, radiation,
beam constraint)

8. Energy Calibration : DØ
DØ uses electrons only but even at large 
Calibration with Z  ee
in CC and EC
(limited by Z statistics)
MW = 181 MeV (EC)
MW = 59 MeV (CC+EC)

9. CDF : MT fit Wen : MW=80.4730.113 GeV Wem : MW=80.4650.143 GeV
Combined result (RunIb /95) :
MW(e+m) = 0.089 GeV
Combined result (Run 0, Ia, Ib /95):
MW(e+m) = 0.079 GeV

10. DØ : MW Combined (CC+EC) MW=80.4800.126 GeV Combined (CC+EC)
Fit of MT :
MW=80.7570.230 GeV (EC)
Combined (CC+EC)
MW=80.7400.097 GeV
Fit of pt(e) :
MW=80.5470.240 GeV (EC)
Combined (CC+EC)
MW=80.4800.126 GeV
Fit of pt(n) :
MW=80.7400.348 GeV (EC)
Combined (CC+EC)
MW=80.4360.171 GeV
Combined result (Run Ia, Ib) :
MW = 0.091 GeV

11. MW : World Average (direct measurements)

12. GW direct measurement Transverse Mass Mt depends on G(W)
Fit region Mt > 100GeV :
line shape dominates over detector resolution
but smaller statistics

13. Results of the fits for GW
CDF (Run Ib) - W en :
G(W)=2.170.1250.105 GeV
CDF (Run Ib) - W mn :
G(W)=1.780.1950.135 GeV
CDF Results electron (Ia-Ib) and muon (Ib) :
GW = 2.0550.1000.075 GeV

14. Lepton t-e Universality
Ratio of from
Luminosity errors cancel
t-e universality at 2.5%

15. Top Quark Physics At the Tevatron top quarks are produced by :
quark annihilation (90%)
gluon fusion (10%)
BR(tbW) ~ 100 % q t b W+ W- l+ n
Three types of analysis :
dileptons (+2b+2n)
lepton + jets
all jets
Channel BR
All jets 44%
e+jets 15%
m+jets 15%
t+X 21%
ee 1.2%
mm 1.2%
em 2.5%
b tagging :
Soft lepton (CDF+DØ)
Displaced vetex (CDF)

16. CDF Top Event
tt2b+2jets+e++

17. Top cross-section CDF updated : b-tagging Luminosity
soft lepton tagging
No excess

18. Top Mass Procedure : Select top candidates (avoid to bias top mass)
Each event is fitted according to top hypothesis
Likelihood fit of Background (QCD, W+jets) + Signal (Herwig) distributions for various values of mtop
Fit of
Top mass value estimation
CDF
All jets
6 jets
at least 1 SVX
Reconstruct mass
from best 2

19. CDF : Lepton + jets Isolated lepton (<1) at least 4 jets
Et>20GeV
4 samples :
SVX (dble tag) #5
SVX (single tag) #15
SLT (without SVX) #14
no tag #42
4 fits

20. DØ : Dilepton 6 dilepton candidates
Mass weight curves calculated from :
Matrix element
Neutrino phase space
Matrix Element
Neutrino
Likelihood fit
of weight sum :

21. Combined Results
Mtop = 174.35.1GeV

22. Constraints on the Higgs mass
MW constraint ~ Mtop constraint

23. Single Top production s channel t channel Signal W+b+b =0.73±0.04pb
Signal W+b+q
=1.70±0.09pb
Cross-section ~ tt production but huge background
42 events
15 events
s < 15.4 pb (95%CL)
s < 15.8 pb (95%CL)

24. Top decay in Charged Higgs
Charged higgs Analysis :
Appearance / Direct search :
look for H+  tn signature (large tanb)
Disappearance / Indirect search :
deficit of top quark (small & large tanb)
Cross-section independent search:
deficit of dilepton events w.r.t leptons+jets
(small & large tanb - (tt) ind.)
(use : Mtop=175 GeV)

25. Z’ & W’ searches - TGC
Additional Z ’ and W ’ expected in many extensions of SM
Tevatron limits obtained from Dilepton / Dijet events
Mass limits depend on the coupling constants
95% C. L. (GeV/c2) L(pb-1)
Z’  e+e- > CDF(110)
Z’  m + m - > CDF(107)
Z’  l+l- > CDF(107)
Z, Z, Z , ZI  l+l- > 580,610,585,555 CDF(110)
ZLR, ZALRM  l+l- > 620, 590 CDF(110)
W’  en > D0(1a,1b)
W’R  eNR > D0(1a,1b)
W’R  eNR > D0(1a,1b)
W’  mn > CDF(107)
W’  WZ > CDF(90)
W’  jj 300 < MW’ <420 CDF(90)
WWg / WWZ couplings (LFF = 2 TeV, Dkg=DkZ, lg=lZ)
-0.30 < Dk < 0.43
-0.20 < l < 0.20
-0.52 < < 0.78

26. Run II - Upgrade Tevatron - II DØ CDF
Increase energy from 1.8 to 2.0 TeV
2 fb-1 in two years … then 5 fb-1 until LHC ? DØ
2T solenoid
8 layer fiber tracker
4 layer silicon barrel
Preshower
Extended muon coverage
CDF
5 layer double sided
silicon barrel
Intermediate silicon layers
New plug calorimeters
extended muon coverage
Better m / b-tagging

27. Run II Physics Top Physics : (tt)40% (s ) Mtop ~ 3 GeV
Measurement of tt invariant mass spectrum
Measure BR(tWb) to 9%
Look for rare decays
(limit to BR(tH+b)<11%)
Top width to 25%
Measurement of |Vtb| ~15 %
Each Experiment could reach Mw~ 40 MeV

28. Conclusion Many Results from Run I : Z/W cross-section
Branching Ratios
GW and MW measurements
Top Discovery
Mtop
cross-section
Top decay
In the future (Run II) :
W and Top mass combination DMHiggs~ 40%MHiggs
Current MW + Mtop - Run II error
MHiggs < C.L.