ph t ev - radcor2000.slac.stanford.edu
TRANSCRIPT
Electroweak Physics at the TeVatron
Kevin McFarland
University of Rochester
RADCOR-2000
Carmel-by-the-Sea, California
11 September 2000
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 2
NuTeV
CDF D0
Main
TeVatron
Injector
1. Introduction, Goals, Musings
2. On-Shell Physics
� W Properties
� Multi-Boson Final States
3. O�-Shell Physics
� NuTeV sin2 �W
� Drell-Yan4. Discovering a Higgs
5. Conclusions
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 3
Status of TeVatron
Where’s CDF?
Cosmicin COT,
Calorimeter
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 4
Status of TeVatron (cont'd)
� TeVatron has achieved
pp collisions
with Main Injector
.ps = 1960 GeV
. L � 1027, c.f. design
L of 2� 1032
� CDF being installed for (short) \commissioning" run
� CDF/D0 to be ready for beam by March 1, 2001
. \or else"
� Initial running with 36 bunch operation in machine
. Occupancy a concern
0.1
1.0
10.0
100.0
Average Number ofInteractions per Crossing
1E+
30
1E+
31
1E+
32
1E+
33
Luminosity
10 3 0
10 3 1
10 3 2
10 3 3
6 Bunches
36 Bunches
108 Bunches
designlum.
. Hope for quick transition to 99 bunch operation,
Æt = 132 ns
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 5
Status of Precision Electroweak
Measurements:
A Three Hour Tour?
A dozen years ago. . .
� The basic structure of the electroweak Standard Modelappeared correct
. Low-energy measurements of � Z interference and Z ex-
change
. Crude boson masses
� Time was ripe for a quick BIG SURPRISE
. Fat Z?
. Generation dependence in couplings?
. Physics at TeV mass scales appearing in precision measure-
ments?
. Other
�Who ordered this?
. Certainly not an experimentalist!
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 6
Status of Precision Electroweak
Measurements (cont'd)
Measurement Pull Pull-3 -2 -1 0 1 2 3
-3 -2 -1 0 1 2 3
mZ [GeV]mZ [GeV] 91.1875 ± 0.0021 .05
ΓZ [GeV]ΓZ [GeV] 2.4952 ± 0.0023 -.42
σhadr [nb]σ0 41.540 ± 0.037 1.62
RlRl 20.767 ± 0.025 1.07
AfbA0,l 0.01714 ± 0.00095 .75
AeAe 0.1498 ± 0.0048 .38
AτAτ 0.1439 ± 0.0042 -.97
sin2θeffsin2θlept 0.2321 ± 0.0010 .70
mW [GeV]mW [GeV] 80.427 ± 0.046 .55
RbRb 0.21653 ± 0.00069 1.09
RcRc 0.1709 ± 0.0034 -.40
AfbA0,b 0.0990 ± 0.0020 -2.38
AfbA0,c 0.0689 ± 0.0035 -1.51
AbAb 0.922 ± 0.023 -.55
AcAc 0.631 ± 0.026 -1.43
sin2θeffsin2θlept 0.23098 ± 0.00026 -1.61
sin2θWsin2θW 0.2255 ± 0.0021 1.20
mW [GeV]mW [GeV] 80.452 ± 0.062 .81
mt [GeV]mt [GeV] 174.3 ± 5.1 -.01
∆αhad(mZ)∆α(5) 0.02804 ± 0.00065 -.29
Osaka 2000
(Figure courtesy of LEP EWWG)
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 7
Status of Precision Electroweak
Measurements (cont'd)
0
2
4
6
10 102
103
mH [GeV]
∆χ2
Excluded Preliminary
∆αhad =∆α(5)
0.02804±0.00065
0.02755±0.00046
theory uncertainty
(Figure courtesy of LEP EWWG)
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 8
Struggling to Find New Physics
Where, if anywhere in the precision data, are there
indications for deviations from Standard Model
expectations in the precision data that would guide us as
we begin to search again at the TeVatron?
� sin2 �e�; leptonsW
vs sin2 �e�; quarksW
� Also �0had
10 2
10 3
0.23 0.232 0.234
Preliminary
sin2θlept
eff
mH [
GeV
]
χ2/d.o.f.: 5.7 / 5
χ2/d.o.f.: 11.9 / 6
Afb0,l 0.23099 ± 0.00053
Aτ 0.23192 ± 0.00053Ae 0.23117 ± 0.00061Afb
0,b 0.23225 ± 0.00036Afb
0,c 0.23262 ± 0.00082<Qfb> 0.2321 ± 0.0010
Average(LEP) 0.23184 ± 0.00023
Al(SLD) 0.23098 ± 0.00026
Average(LEP+SLD) 0.23146 ± 0.00017
∆αhad= 0.02804 ± 0.00065∆α(5)
αs= 0.119 ± 0.002mt= 174.3 ± 5.1 GeV
� Atomic Parity
Violation (137Cs)
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 9
Atomic Parity Violation
� Z Interference
e
e
Z,γ
� Interaction suppressed by q2=M 2Z
� But not in forbidden (6S $ 7S) transitions (parity-violating)
� Magnitude of interference (parity-violating) relative to -exchange
gives
hQW i = hQEMi (light quarks)
Recent 137Cs APV measurement
Bennett,S.C. and Wieman,C.E. PRL 82, 2482-2487 (1999)
QW = �72:06� 0:28(exp)� 0:34(theory)
QSMW = �73:09� 0:03
\I believe our sigmas mean a bit more than the
sigmas that you use [in particle physics]."
Carl Wieman, at an FNAL Seminar
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 10
On-Shell or O�-Shell?
� LEP Z pole data disfavors most new physics in the
weak neutral current itself
� However, this constraint still
allows for new physics in o�-
shell processes
� New interactions can't strongly
a�ect Z pole
� E.g., Z 0 exchange, unmixed
Z’
Z’
Z’Z
Z
q
l
l
q
l
q
Pure Z’ exchange
Z-Z’ Mixing
� Global �t shows some Z-Z 0 mixing allowed
. � 10�3 weakly favored?Langacker and Erler, PRL 84, 212-215 (2000)
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 11
On-Shell (W Properties)
p_
p
W,Z, γ
l
l, ν
� W production is dominant source of
high pt leptons at TeVatron
�(pp! W )� BR(W ! `�)
�(pp! Z)� BR(Z ! ``)� 10
� Drell-Yan extends
to very high
mass `+`� pairs
� Generally clean,
\obvious" sample0
200
400
600
800
1000
1200
25 30 35 40 45 50 55pT(e) (GeV)
num
ber
of e
vent
s
candidatesW e νD0
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 12
W Mass
� �, GF , MZ ) MW at tree level
� MW measurement probes radiative corrections
W W
t
b
W W
h0
W∆MW α MT
2 ∆MW α ln MH
W W
?
?New Physics
. Constraint on Higgs mass
. Key consistency check for model
80.1
80.2
80.3
80.4
80.5
80.6
130 140 150 160 170 180 190 200Mtop (GeV/c2)
MW
(G
eV/c
2 )
100
250
500
1000
Higgs Mass (
GeV/c2 )
TEVATRON
MW-Mtop contours : 68% CL
LEP2
LEP1,SLD,νN dataMW-Mtop contours : 68% CL
80.1
80.2
80.3
80.4
80.5
80.6
130 140 150 160 170 180 190 200
�Mtop= 5:1 GeV, �MW
= 63 MeV
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 13
W Mass (cont'd)
CDF/D0 Technique:
� Infer neutrino transverse
kinematics from~p�T = � ~uT � ~p`T
uT
lepton
ν
� Form mT =r2p`Tp
�T (1� cos(�` � ��))
� Select events with high p`T (25 or 30 GeV)and low uT (below 15 or 20 GeV)
. CDF,D0: central,�����`
���� < 1
. D0: endcap e, 1:5 <�����`
���� < 2:5 (� 30% of sample)
. � 4� 104 events per experiment
� Fit mT to extract mW
(D0 �ts p`t and p�t as well)
0
500
1000
1500
2000
50 60 70 80 90 100 110 120
CDF(1B) PreliminaryW→eν
χ2/df = 82.6/70 (50 < MT < 120)
χ2/df = 32.4/35 (65 < MT < 100)
Mw = 80.473 +/- 0.065 (stat) GeV
KS(prob) = 16%
Fit region
Backgrounds
Transverse Mass (GeV)
# E
vent
s
0
50
100
150
200
250
300
350
400
450
500
50 60 70 80 90 100 110 120
CDF(1B) PreliminaryW→µν
χ2/df = 147/131 (50 < MT < 120)
χ2/df = 60.6/70 (65 < MT < 100)
Mw = 80.465 +/- 0.100 (stat) GeV
KS(prob) = 21%
Fit region
Backgrounds
Transverse Mass (GeV)
# E
vent
s
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 14
W Mass (cont'd)
Systematics: p`t measurement
� Primary control from Z ! `+`� data
0
50
100
150
200
250
70 80 90 100 110
CDF(1B) Preliminary
Z→ee χ2/df=1.3
0
50
100
150
200
250
80 90 100
CDF(1B) Preliminary
Z→µµ χ2/df=0.89
-0.01
-0.005
0
0.005
0.01
30 40 50 60
CDF(1B) Preliminary
ET (GeV) : W+Z events
E/p
Res
idua
ls:D
AT
A-M
C
W Z
∆Mw = 34 +/- 17 MeV
� Attempt to cross-check this with E=p determination in
CDF 1B electron data failed by 4�, (�MZ � 500MeV)
� Highlights diÆculty of measurement
� ÆMW � 70{85 MeV (Run I)
Systematics: Recoil Model
� Response of detectors to underlying event
� Measured (again) in Z ! `+`� data
� ÆMW � 30{40 MeV (Run I)
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 15
W Mass (cont'd)
Systematics: d�=dy
� Direct e�ect on lineshape in �t
Well constrained from W charge asymmetry
-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2
0.25
0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5
d/u : Variation for Mw analysis
MRS-TMRS-T(MOD)
MRS-R1(MOD)MRS-R1
MRS-R2MRS-R2(MOD)
Lepton Rapidity
Cha
rge
Asy
mm
etry
� ÆMW � 10{20 MeV (Run I)
Systematics: Scaling for Run II
� Most systematics now directly constrained from W;Z
data ) statistically limited
0
50
100
150
200
250
300
350
400
450
500
0 0.1 0.2 0.3 0.4 0.5 0.6
� Anticipate �MWof 20{40 MeV
from �rst 2fb�1 (early 2003?) from CDF/D0
� Control of theoretical systematics also key { see talk by D. Wackeroth
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 16
W Width
� TeVatron high statistics W sample ideal for study of
W properties
� Run II (2 fb�1 per experiment),
expect 106 W
� W lineshape as a measure of
�W
� High mT dominated by Breit-
Wigner, not resolution MT(e,ν) (GeV)
Transverse mass lineshape(normalized to unit area)for ΓW=1.5,1.7,...,2.5 GeV
CDF Preliminary
10-5
10-4
10-3
10-2
10-1
40 60 80 100 120 140 160 180 200
MT(e,ν) (GeV)
even
ts /
GeV CDF(1B) Preliminary
ΓW = 2.175 ± 0.165 GeV(stat+syst)
MT(e,ν) (GeV)
even
ts /
2GeV 49844 events shown
(1490 ± 170 bkg)438 with 100<MT<200 GeV211 with 110<MT<200 GeV
7 with MT>200 GeV
0
1000
2000
40 60 80 100 120 140 160 180 200
1
10
10 2
10 3
40 60 80 100 120 140 160 180 200
-2 log(L) vs ΓW
325
330
335
340
345
350
355
360
1.6 1.8 2 2.2 2.4 2.6 2.8
MT(µ,ν) (GeV)
# E
vent
s
CDF(1B) PreliminaryΓW = 1.78 +- 0.240 GeV
ΤW
-2 lo
g(L
)
MT(µ,ν) (GeV)
# E
vent
s
Backgrounds
196 ev. in fit region(100 < MT < 200)
21791 ev. in normalisation region(50 < MT < 200)
0
250
500
750
1000
50 100 150 200
246
248
250
252
1 1.5 2 2.5 3
10-1
1
10
10 2
10 3
50 100 150 200
CDF
�W = 2:055� 0:100� 0:075
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1.5 1.6 1.7 1.8 1.9 2 2.1 2.2 2.3 2.4 2.51.5 2.0 2.5ΓW[GeV]
ALEPH 2.17±0.20
DELPHI 2.09±0.15
L3 2.19±0.21
OPAL 2.04±0.18
LEP 2.12±0.11
LEP Preliminary : Summer 2000
-CDF 2.06+0.12
Run II (2 fb�1),
��W � 20{40 MeV
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 17
W/Z Production
� W , Z boson production also is a clean way to
probe proton constituents
p_
x2
pl
l, νW,Z
x1
� MV =px1x2s
� Role in precision measurements
. e.g., W mass and W asymmetry
-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2
0.25
0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5
d/u : Variation for Mw analysis
MRS-TMRS-T(MOD)
MRS-R1(MOD)MRS-R1
MRS-R2MRS-R2(MOD)
Lepton Rapidity
Cha
rge
Asy
mm
etry
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 18
W/Z Production (cont'd)
0
10
20
30
40
50
60
70
80
0 0.5 1 1.5 2 2.5 3y
dσ(γ* /Z
)/d
y (
pb
)
CDF 1992-95 e+e-
χ2/ndofLO(CTEQ5L), 33.3/27NLO(MRST99), 23.1/27NLO(CTEQ5M-1), 24.3/27
x2
x1
x1=MZeys-1/2
x2=MZe-ys-1/2
66< Mγ*/Z < 116 GeV/c2
(a)
0.031 0.019 0.011 0.007 0.004
0.05 0.084 0.138 0.227 0.374 0.617 1.0
Forward e� reconstruction key for these measurements
Silicon tracking and EM calorimetry only!
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
-3 -2 -1 0 1 2 3
CC,CP,CF,PP,PF CC,CP,CF CC
y
εAr
COT
0
.5
1.0
1.5
2.0
0 .5 1.0 1.5 2.0 2.5 3.0
END WALLHADRONCAL.
SVX II5 LAYERS
30
3 00
SOLENOID
INTERMEDIATE SILICON LAYERS
CDF Tracking Volume
= 1.0
= 2.0
EN
D P
LUG
EM
CA
LOR
IME
TER
EN
D P
LUG
HA
DR
ON
CA
LOR
IME
TER
= 3.0
n
n
n
m
m
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 19
Gauge Boson Couplings
� Standard Model allows for non-zero trilinear
Gauge boson couplings
. WW , WWZ allowed
. ZZ , Z , ZZZ zero at tree level
� Search for non-Standard couplings to probe structure
of physics beyond Standard Model
� Multi-boson signatures clean if W;Z ! leptons
. again, waiting increased LCAL+TKS END VIEW 15-MAY-1997 13:27 Run 89912 Event 23020 26-MAR-1995 22:54
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MUON
ELEC
TAUS
VEES
OTHER
EM
ICD+MG
HAD
MISS ET
Max ET = 51.6 GeV MISS ET(3)= 40.8 GeV ETA(MIN:-25-MAX: 25)
EM2
EM3
EM1
Miss. Et
MT(2)=74.7 GeV M13=93.6 GeV
Run I D0 WZ candidate!
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 20
Gauge Boson Couplings (cont'd)
ALEPH 0.09 +0.18−0.14
DELPHI 0.25 +0.21−0.17
L3 −0.12 +0.16−0.14
OPAL 0.00 +0.27−0.19
LEP 0.06 +0.09−0.09
D0 −0.05 +0.30−0.30
LEP+D0 0.05 +0.09−0.08
preliminary
χ2/Ndof = 2.08/4
∆κγ
-∆ln
L
0
1
2
3
-0.5 0 0.5
ALEPH −0.05 +0.07−0.06
DELPHI 0.02 +0.08−0.08
L3 0.00 +0.07−0.07
OPAL −0.11 +0.08−0.07
LEP −0.03 +0.04−0.04
D0 0.00 +0.10−0.10
LEP+D0 −0.03 +0.03−0.03
preliminary
χ2/Ndof = 1.48/4
λγ
-∆ln
L
0
1
2
3
-0.2 -0.1 0 0.1 0.2
� Expect scaling withpL (or better)
� WZ signature unique to hadron colliders
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 21
O�-Shell: NuTeV
ACCEPTEDπ,Κ
DUMPEDπ,Κ
Right-SignDUMPEDNuTeV
SSQT Sign TrainQuadrupoleSelected
��������
Wrong-Sign
Protons
�NC
�CC
+sin2 ��NW
Event Length
ν
q q
W
µ
Event Length
q
ν
q
Z
ν
Short (NC) Events Long (CC) Events R20 � Short=Long
� 386K 919K 0:4198� 0:0008(stat)
� 88.7K 210K 0:4215� 0:0017(stat)
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 22
PRELIMINARY NuTeV sin2�W
NuTeV measures:
sin2�W
(on�shell)=
0:2253� 0:0019(stat)� 0:0010(syst)
sin2 �(on�shell)W � 1� MW
2
MZ2
� The most precise �N measure-
ment of the weak mixing angle
� Precision comparable to collider
measurements ...
79.9 80.1 80.3 80.5 80.7 80.9Mw (GeV)
UA2
CDF*
D0*
NuTeV*
ALEPH*
DELPHI*
L3*
OPAL*
World Average
* : Preliminary
80.26 +/- 0.110
80.360 +/- 0.370
80.433 +/- 0.079
80.482 +/- 0.091
80.449 +/- 0.065
80.308 +/- 0.091
80.353 +/- 0.088
80.446 +/- 0.064
80.419 +/- 0.038
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 23
NuTeV sin2�W (cont'd)
R�=
��NC � ��NC��CC � ��CC
=
0B@1
2� sin2 �W
1CA
= u2L + d2L � u2R � d2R
NuTeV measurement! constraint on the Z0-quark couplings:
0:4530� sin2 �W =
0:2277� 0:0022 =
0:8587u2L + 0:8828d2L � 1:1657u2R � 1:2288d2R
g2L;R = u2L;R + d2L;R
0.02
0.03
0.04
0.29 0.3 0.31
SM
NuTeV R�constraint:
�0:0068� 0:006 =
+ 1:6134�uL + 0:9972�uR� 2:0631�dL � 0:5261�dR
APV constraint:
(QexpW �QSM
W )=QSMW =
0:014� 0:006 =
+ 5:1436(�uL +�uR)
+ 5:7729(�dL + �dR)� 2�geA
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 24
Extra Z Bosons?
� Several authors have suggested E(6) Z 0 as the mostnatural interpretation of APV data
. Rosner, Casalbuoni et al, unmixed Z 0
. Erler and Langacker, general case
� APV, NuTeV (and pp Drell-Yan) all sensitive to direct
Z 0 exchange (interference)
95% Con�dence Level Lower Mass Limits on Z0
':
Z0
= Z�cos� + Z sin�
NuTeV Limits (mixing=-10�3) Rosner hep-ph/9907524
mZ� � 675 GeV at 95% CL Casalbuoni, et al. hep-ph/0001215
mZ� � 380 GeV at 95% CL
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 25
High Mass Drell-Yan
� Search for highest
mass `�`�
� Sensitive to
``qq contact inter-
actions, Z 0
D0 Run I
e+e� sample
� Sample is clean, fertile ground for new physics
Comparison of the data with the SM predictions
10-2
10-1
1
10
10 2
10 3
0 100 200 300 400 500 600
M(EM-EM), GeV
Eve
nts
M(EM-EM), GeVM(EM-EM), GeVM(EM-EM), GeV
DØ (2000)Run I, 127 pb-1
Dielectrons and diphotons
ET(EM) > 45 GeV
|η| < 1.1 or 1.5 < |η| < 2.5
SM
Instrumental background
Limits on Large Spatial Extra Dimensions
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2MS , TeV
F/M
S ,4 T
eV −
4
n = 2, MS > 1.37 TeVn = 3, MS > 1.44 TeV
n = 4, MS > 1.21 TeVn = 5, MS > 1.10 TeV
n = 6, MS > 1.02 TeV
n = 7, MS > 0.97 TeV
95% CL UpperLimit on F/MS
4
F = 2/(n-2), n > 2
F = 2log( ), n = 2
(after Han et al.
PRD 59 (1999) 1050060)
MS
0.6 TeV
DØ (2000)
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 26
High Mass Drell-Yan (cont'd)
p_
p
W,Z, γ
l
l, ν
� O�-shell, forward-backward asymmetry is large
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
60 80 100 120 140 160 180 200
� Assume Standard Model behavior on Z pole;
probe high-mass region and therefore interference
� CDF new result in process;
enhanced angular coverage using forward events!
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 27
High Mass Drell-Yan (cont'd)
� Forward e� de�ned by EM calorimeter. . .
� . . . in conjunction with silicon stub
. charge determination!
y
φcal
pTmax
pTmin
rcal
� Probing o�-shell (interference) key for Z 0 searches!
(Rosner, Phys. Rev. D54 1078)
� �=Z�=Z 0� interference is sig-
nature of Z 0
� Di�erentiates among E(6) Z 0
possibilities
� Just awaiting L:::
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 28
90 130
σ(pp_→H+X) [pb]
√s = 2 TeV
Mt = 175 GeV
CTEQ4Mgg→H
qq→Hqqqq
_’→HW
qq_→HZ
gg,qq_→Htt
_
gg,qq_→Hbb
_
MH [GeV]
10-4
10-3
10-2
10-1
1
10
10 2
80 100 120 140 160 180 200
Standard Model Higgs
� Discovery of the Higgs would complete the experimen-
tal veri�cation of the electroweak Standard Model
� SM Higgs:
. Single doublet of scalar �elds
. Predicts couplings but not Higgs mass
Decay
� For 90 < MH < 130GeV,
BR(H ! b�b) varies between
0.85 and 0.60.
� At MH > 140 GeV,
H ! WW � dominates
Production at TeVatron
� V H production provides
additional handle for
background rejection.
� �(WH)=�(ZH) � 1:6
� gg ! H, H ! bb
hopeless at TeVatron
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 29
CDF Run I Searches
No signal observed !
WH ! `� b�b V H ! qqb�bExpect : 30� 5 1-tag, 6:0� 0:6 2-tag Expect : 600 2-tag events
Observe : 36 1-tag, 6 2-tag Observe : 589 2-tag events
0
1
2
0 50 100 150 200 250 300
Entries 5
Data (5 events)
Total background (3.2 events)
Dijet Mass (GeV)
Eve
nts
/ (10
GeV
)
ZZ + tt + mistags only
ZH ! `+`� b�b ZH ! ��b�bExpect : 3:2� 0:7 1-tag Expect : 39:2� 4:4 1-tag, 3:9� 0:6 2-tag
Observe : 5 Observe : 40 1-tag, 4 2-tag
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 30
1
10
10 2
70 80 90 100 110 120 130 140
Higgs Mass (GeV/c2)
σβ (
pb)
σ(pp− → VH0)β CDF 95% C.L.
CDF PRELIMINARY
VH0 → qq− bb
−
VH0 → lν− bb
−
combined (lν−, qq
−)
VH0 → νν− bb
−
combined :VH0 → l+l- / νν
− bb
−
standard model
CDF Run I Searches (cont'd)
� Limits � 50� SM expectations with 0:1 fb�1
� 2 fb�1 is still not enough
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 31
Run II Prospects
0
2
4
6
10 102
103
mH [GeV]
∆χ2
Excluded Preliminary
∆αhad =∆α(5)
0.02804±0.00065
0.02755±0.00046
theory uncertainty
� Precision data stronglysuggest that Higgs is
below 190 GeV
� Suggests opportunity
at TeVatron with high
luminosity
� Two mass ranges:
. MH < 130 GeV
H ! bb
. MH > 130 GeV
H ! WW �
MH < 130 GeV MH > 130 GeV
V H V H and gg
`�bb, ��bb, `+`�bb `+`+jj, `+`+`�, `+`�
-20
-10
0
10
20
30
40
50
0 20 40 60 80 100 120 140 160 180 200
Dijet Invariant Mass (GeV/c2)
Eve
nts
per
10 G
eV/c
2
Excess over background— Expected MC shape (PYTHIA)
Predicted bgr.
Observed events
Dijet Mass (GeV/c2)
Eve
nts
per
10 G
eV/c
2
0
20
40
60
80
100
0 50 100 150 200
Low backgrounds make
analysis viable, even with
low cross-sections and low
branching ratios into lep-
tons
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 32
Run II Prospects
Run 2B
Run 2
(Run II Higgs Working Group, All V H Channels and
gg ! H;H ! WW � )
� With 2 fb�1 can probe MH up to � 115GeV/c2.
� Need � 20 fb�1 for a 3� signal for MH to 180 GeV
� Prospects for luminosity beyond 15 fb�1 before LHC
are unclear
Kevin McFarland, RADCOR-2000, Electroweak Physics at the TeVatron 33
Conclusions
The TeVatron is Poised
for a Long Run!
� \The Signature" for Run II is W/Z ! `(�=`)
. 106 W by 2003!
. Precision measurements: W mass and width
. Using W as a tool: parton distributions,
luminosity calibration for TeVatron
. Multi-boson production
� \The targets" for New Physics in Run II (2 fb�1)
. Z 0 (testing Wieman's \sigma" calibration)
. Weak couplings of top (Willenbrock's talk)
� Standard Model Higgs
. Requires 10{20 fb�1 to get in the game
. TeVatron is a tough place to study a
114:9 GeV Higgs (just to pick a random number)
. Good news: broad range of masses accessible!
. More good news: H ! WW � clean