IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 1
XXXVI International Meeting on XXXVI International Meeting on Fundamental PhysicsFundamental Physics
Rick FieldUniversity of Florida
(for the CDF & D0 Collaborations)
CDF Run 2
Palacio de Jabalquinto, Baeza, Spain
From IMFP2006 → IMFP2008
Physics at the Tevatron
2nd LectureBosons, Top, and Higgs
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 2
Tevatron PerformanceTevatron Performance
Luminosity records (IMFP 2008): Highest Initial Inst. Lum: ~2.92×1032 cm-2s-1 Integrated luminosity/week: 45 pb-1
Integrated luminosity/month: 165 pb-1
IMFP 2008~3.3 fb-1 delivered~2.8 fb-1 recorded
IMFP 2006~1.5 fb-1 delivered~1.2 fb-1 recorded
Luminosity Records (IMFP 2006): Highest Initial Inst. Lum: ~1.8×1032 cm-2s-1 Integrated luminosity/week: 25 pb-1
Integrated luminosity/month: 92 pb-1
~1.6 fb-
1
Integrated Luminosity per Year
The data collected since IMFP 2006 more than doubled the total data collected in Run 2!
23 tt-pairs/month!
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 3
Many New Tevatron Results!Many New Tevatron Results!
Observation of Bs-mixing: Δms = 17.77 ± 0.10 (stat) ± 0.07(sys).
Observation of new baryon states: b and b.
Observation of new charmless: B→hh states. Evidence for Do-Dobar mixing . Precision W mass measurement: Mw = 80.413 GeV (±48 MeV).
Precision Top mass measurement: Mtop = 170.5 (±2.2) GeV.
W-width measurement: 2.032 (±0.071) GeV. WZ discovery (6-sigma): = 5.0 (±1.7) pb. ZZ evidence (3-sigma). Single Top evidence (3-sigma) with 1.5 fb-1: = 3.0 (±1.2) pb. |Vtb|= 1.02 ± 0.18 (exp) ± 0.07 (th).
Significant exclusions/reach on many BSM models. Constant improvement in Higgs Sensitivity.
Some of the CDF Results since IMFP2006
I cannot possibility cover all the great physics results from theTevatron since IMFP 2006!I will show a few of the results!
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 4
Z-boson Cross Section (CDF)Z-boson Cross Section (CDF)
Impressive agreement between experiment and NNLO theory (Stirling, van Neerven)!
CDF (pb) NNLO (pb)
(Z→e+e-) 254.93.3(stat)4.6(sys)15.2(lum) 252.35.0
L = 72 pb-1
QCDDrell-Yan
IMFP2006
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 5
Z-boson Cross Section (CDF)Z-boson Cross Section (CDF)
Impressive agreement between experiment and NNLO theory (Stirling, van Neerven)!
CDF (pb) NNLO (pb)
(Z→+-) 261.22.7(stat)6.9(sys)15.1(lum) 252.35.0
L = 337 pb-1IMFP2006
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 6
Z-Boson Rapidity DistributionZ-Boson Rapidity Distribution Measure d/dy for Z→e+e-. Use electrons in
the central (C) and plug (P) calorimeter.
Parton momentum fractions x1 and x2 determine the Z boson rapidity, yZ.
Production measurement in high yZ region probes high x region of PDF’s.
Plug-plug electrons, ZPP, are used to probe the high x region!
Zcc Zcp Zpp
CDF ZCC ZCP ZPP
Events 28,097 46,676 16,589
1.1fb-1 91,362 events 66 < MZ < 116 GeV
since IMFP2006
Plug-Plug electrons!
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 7
Z-Boson Rapidity DistributionZ-Boson Rapidity Distribution CDF measured d/dy for Z/*
compared with an NL0 calculation using CTEQ6.1M PDF.
The NLO theory is scaled to the measured (Z)!
No PDF or luminosity uncertainties included.
since IMFP2006
CDF (pb) NNLO (pb)
(Z→e+e-) 263.3±0.9(stat)±3.8(sys) 252.35.0
NLO + CTEQ6.1 PDF NLO + MRST PDFNLL0 + NNL0 MRST PDF
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 8
The ZThe Z→→ Cross Section (CDF) Cross Section (CDF)Signalcone
Isolationcone
Taus are difficult to reconstruct at hadron colliders• Exploit event topology to suppress backgrounds (QCD & W+jet).
• Measurement of cross section important for Higgs and SUSY analyses.
CDF strategy of hadronic τ reconstruction: • Study charged tracks define signal and isolation cone (isolation = require no
tracks in isolation cone).
• Use hadronic calorimeter clusters (to suppress electron background).
• π0 detected by the CES detector and required to be in the signal cone.
CES: resolution 2-3mm, proportional strip/wire drift chamber at 6X0 of
EM calorimeter.
Channel for Z→ττ: electron + isolated track• One decays to an electron: τ→e+X (ET(e) > 10 GeV) .
• One decays to hadrons: τ → h+X (pT > 15GeV/c).
Remove Drell-Yan e+e- and apply event topology cuts for non-Z background.
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 9
The ZThe Z→→ Cross Section (CDF) Cross Section (CDF) CDF Z→ττ (350 pb-1): 316 Z→ττ candidates. Novel method for background estimation: main contribution QCD. τ identification efficiency ~60% with uncertainty about 3%!
1 and 3 tracks,
opposite signsame sign,
opposite sign
CDF (pb) NNLO (pb)
(Z→+-) 26520(stat)21(sys)15(lum) 252.35.0264 ± 23 (stat) ± 14 (sys) ± 15 (lum)
IMFP2006
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 10
Higgs Higgs → → Search (CDF) Search (CDF)
Data mass distribution agrees with SM expectation:
• MH > 120 GeV: 8.4±0.9 expected, 11 observed.
Fit mass distribution for Higgs Signal (MSSM scenario):
• Exclude 140 GeV Higgs at 95% C.L.
• Upper limit on cross section times branching ratio.
140 GeV Higgs Signal!
events
1 event
IMFP2006
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 11
Higgs Higgs → → Search (CDF) Search (CDF)events events
No Significant Excess of events above SM background is observed!
since IMFP2006
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 12
W-bosonW-boson Cross Section (CDF) Cross Section (CDF)
(W) L CDF (pb) NNLO(pb)
Central
electrons72 pb-1 277510(stat)53(sys)167(lum) 268754
Forward
electrons223 pb-1 281513(stat)94(sys)169(lum) 268754
CDF NNLO
(W)/(Z) 10.920.15(stat)0.14(sys)
10.690.08
Extend electron coverage to the forward region (1.2 < || < 2.8)!
48,144 W candidates ~4.5% background48,144 W candidates ~4.5% background overall efficiency of signal ~7% overall efficiency of signal ~7%
W Acceptance
IMFP2006
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 13
W-Boson Mass MeasurementW-Boson Mass MeasurementThe Challenge:
Do not know neutrino pz.
No full mass reconstruction possible. Extract from a template fit to PT, MT, and
Missing ET.
Transverse mass:
MW = 80413 ± 48 MeV/c2
since IMFP2006
Single most precise measurement to date!
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 14
W-Boson Width MeasurementW-Boson Width MeasurementModel transverse mass distribution
over range 50-200 GeV.Normalize 50-90 GeV and fit for the width in the high
MT region 90-200 GeV.The tail region is sensitive to the width of the Breit
Wigner line-shape.
since IMFP2006
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 15
W Production Charge AsymmetryW Production Charge Asymmetry
WW
WWW dyddyd
dyddydyA
//
//)(
d
uu p
u
udp
W+
e+
e
xG
(x,Q
2)
x
u
d
W- W+
yprotonantiproton
10-3 10-2 10-1 1
There are more u-quarks than d-quarks at high x in the proton and hence the W+ (W-) is boosted in the direction of the incoming proton (antiproton).
Measuring the W± asymmetry constrains the PDF’s!
Q2 = 100 GeV2
MRST2004NLO
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 16
W Production Charge AsymmetryW Production Charge Asymmetry Since the longitudinal momentum of the neutrino,
pL(), is not known the W rapidity cannot be reconstructed.
So previously one looked at the the electron charge asymmetry.
The V-A structure of the W+ (W-) decay favors a backward e+ (forward e-) which “dilutes” the W charge asymmetry!
New CDF measurement performed in W→e channel.
pL() is determined by constraining MW = 80.4 GeV leaving two possible yW solutions. Each solution receives a probability weight according to the V-A decay structure and the W cross-section, (yW).
The process is iterated since (yW) depends on the asymmetry.
since IMFP2006
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 17
W + W + Cross Sections (CDF) Cross Sections (CDF)
CDF (pb) NLO (pb)
(W+)*BR(W->l) 19.71.7(stat)2.0(sys)1.1(lum) 19.31.4
ET() > 7 GeVR(l) > 0.7
IMFP2006
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 18
W + W + Cross Sections (CDF) Cross Sections (CDF)
CDF (pb) NLO (pb)
(W+)*BR(W->l) 19.71.7(stat)2.0(sys)1.1(lum) 19.31.4
ET() > 7 GeVR(l) > 0.7
18.03±0.65(stat)±2.55(sys) ±1.05(lum)
since IMFP2006
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 19
Z + Z + Cross Sections (CDF) Cross Sections (CDF)
CDF (pb) NLO (pb)
(Z+)*BR(Z->ll) 5.30.6(stat)0.3(sys)0.3(lum) 5.40.3
ET() > 7 GeVR(l) > 0.7
Note: (W)/(Z) ≈ 4
while (W)/(Z) ≈ 11
IMFP2006
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 20
Z + Z + Cross Sections (CDF) Cross Sections (CDF)
CDF (pb) NLO (pb)
(Z+)*BR(Z->ee) 4.90.3(stat)0.3(sys)0.3(lum) 4.70.4
ET() > 7 GeVR(l) > 0.7
Mee > 40 GeV/c2
390 events
since IMFP2006
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 21
The W+W Cross-SectionThe W+W Cross-Section
pb-1 CDF (pb) NLO (pb)
(WW) CDF 184 14.6+5.8(stat)-5.1(stat)1.8(sys)0.9(lum) 12.40.8
(WW) DØ 240 13.8+4.3(stat)-3.8(stat)1.2(sys)0.9(lum) 12.40.8
Campbell & Ellis 1999
IMFP2006
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 22
The W+W Cross-Section (CDF)The W+W Cross-Section (CDF)
L CDF (pb) NLO (pb)
(WW) 825 pb-1 13.72.3(stat)1.6(sys)1.2(lum) 12.40.8
WW→dileptons + MET Two leptons pT > 20 GeV/c.
Z veto. MET > 20 GeV. Zero jets with ET>15 GeV
and ||<2.5.Observe 95 events with
37.2 background!
L = 825 pb-1 IMFP2006
Missing ET! Lepton-Pair Mass! ET Sum!
We are beginning to study the details ofDi-Boson production at the Tevatron!
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 23
WW+WZ Cross-SectionWW+WZ Cross-Section
CDF (pb) NLO (pb)
(WW+WZ)×BR(lvjj) 1.47 ± 0.77(stat) ± 0.38(sys) 2.1 ± 0.2 pb
NLO TheoryσWW × Br(W→l, W→jj) = 12.4 pb × 0.146 = 1.81 pbσWZ × Br(W→l, Z→jj) = 3.96 pb × 0.07 = 0.28 pb
since IMFP2006
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 24
The Z+W, Z+Z Cross Sections The Z+W, Z+Z Cross Sections
W+Z, Z+Z Limit (pb) NLO (pb)
CDF (194 pb-1) sum < 15.2 (95% CL) 5.00.4
DØ (300 pb-1) W+Z < 13.3 (95% CL) 3.70.1
Upper Limits
CDF (825 pb-1) W+Z < 6.34 (95% CL) 3.70.1
W+Z → trileptons + METObserve 2 events with a background of 0.9±0.2!
IMFP2006
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 25
The W+Z Cross SectionThe W+Z Cross SectionStrategy Search for events with 3 leptons and missing
energy. Small cross-section but very clean signal. Anomalous cross-section sensitive to non SM
contributions.
L CDF (pb) NLO (pb)
(W+Z) 1.9 fb-1 4.3±1.3(stat) ±0.2(sys) ±0.3(lum) 3.70.3
3.0 σ significance!
since IMFP2006
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 26
The Z+Z Cross SectionThe Z+Z Cross SectionStrategy: Search for events with either 4 leptons or
2 leptons and significant missing ET. Calculate a Prob(WW) or Prob(ZZ) based on event
kinematics and LO cross section. Construct a likelihood ratio. Fit to extract the ll signal.
L CDF (pb) NLO (pb)
(Z+Z) 1.9 fb-1 0.75+0.71-0.54 1.4±0.1
3.0 σ significance!
ZZ decaying into 4 leptons
since IMFP2006
ZZ decaying into 2 leptons + MET
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 27
Higgs Higgs → W+W→ W+W We are within a factor of two of
the standard model Higgs (160 GeV) → WW!
since IMFP2006
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 28
Heavy Quark Production at the TevatronHeavy Quark Production at the Tevatron
Total inelastic tot ~ 100 mb which is 103-104 larger than the cross section for D-meson or a B-meson.
However there are lots of heavy quark events in 1 fb-1!
Want to study the production of charmed mesons and baryons: D+, D0, Ds , c , c , c, etc.
Want to studey the production of B-mesons and baryons: Bu , Bd , Bs , Bc , b , b, etc.
Two Heavy Quark Triggers at CDF:
• For semileptonic decays we trigger on and e.
• For hadronic decays we trigger on one or more displaced tracks (i.e. large impact parameter).
with 1 fb-1
~1.4 x 1014
~1 x 1011
~6 x 106
~6 x 105
~14,000 ~5,000
CDF-SVT
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 29
B-Baryon Observations (CDF)B-Baryon Observations (CDF)
b
bc
b
The Tevatron is excellent at producing particles containing
b and c quarks(Bu, Bd, Bs, Bc, b, b,b)
since IMFP2006
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 30
Top Decay ChannelsTop Decay Channels mt>mW+mb so dominant decay tWb.
The top decays before it hadronizes. B(W qq) ~ 67%. B(W l) ~ 11% l = e,
BR backgrounddilepton ~5% lowlepton + jets ~30% moderateall hadronic ~65% high
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 31
Dilepton Channel (CDF)Dilepton Channel (CDF)Backgrounds:
• Physics: Drell-Yan, WW/WZ/ZZ, Z
• Instrumental: fake lepton
Selection:• 2 leptons ET > 20 GeV with opposite sign.• >=2 jets ET > 15 GeV.• Missing ET > 25 GeV (and away from any jet).• HT=pTlep+ETjet+MET > 200 GeV.• Z rejection.
(tt) = 8.3 ± 1.5 (stat) ± 1.0 (syst) + 0.5 (lumi) pb
65 events
20 eventsbackground
IMFP2006
84 events
since IMFP2006
(tt) = 6.16 ± 1.05 (stat) ± 0.72 (syst) + 0.37 (lumi) pb
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 32
Lepton+Jets Channel (CDF)Lepton+Jets Channel (CDF)
HT>200GeV
(tt ) 8.8 1.11.2 (stat) 1.3
2.0 (syst)pb
b-Taggingb-TaggingRequire b-jet to be tagged for
discrimination.
Tagging efficiency for b jets~50% for c jets~10%
for light q jets < 0.1%
~150 events
(tt) = 8.2 ± 0.6 (stat) ± 1.1 (syst) pb
~45 events
IMFP2006
~180 events
1 b tag
Small background!
~70 events2 b tags
(tt) = 8.2 ± 0.5 (stat) ± 0.8 (sys) ± 0.5 (lum) pb(tt) = 8.8 ± 0.8 (stat) ± 1.2 (sys) ± 0.5 (lum) pb
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 33
Tevatron Top-Pair Cross SectionTevatron Top-Pair Cross Section
Bonciani et al., Nucl. Phys. B529, 424 (1998)Kidonakis and Vogt, Phys. Rev. D68, 114014 (2003)
CDF Run 2 Preliminary
(tt ) 6.7 0.90.7 pb
Theory
since IMFP2006
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 34
Top Quark MassTop Quark Mass
Dilepton Channel
since IMFP2006
Mt=170.4 ± 3.1(stat) ± 3.0(sys)GeV/c2
Leptons+Jets Channel
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 35
Top Cross-Section vs MassTop Cross-Section vs Mass
Tevatron Summer 2005 CDF Winter 2006
Cacciari, Mangano, et al., hep-ph/0303085
CDF combined
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 36
Constraining the Higgs MassConstraining the Higgs Mass
Top quark mass is a fundamental parameter of SM.
Radiative corrections to SM predictions dominated by top mass.
Top mass together with W mass places a constraint on Higgs mass!
Tevatron Run I + LEP2
Summer 05
114 GeV Higgs very interesting for the Tevatron!
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 38
Other Sources of Top QuarksOther Sources of Top Quarks
q
q
t
t
~85%
g
g
Strongly Produced tt PairsStrongly Produced tt PairsDominant production mode
NLO+NLL = 6.7 1.2 pb
Relatively clean signatureDiscovery in 1995
ElectroWeak Production: ElectroWeak Production: Single TopSingle Top
Larger backgroundSmaller cross section ≈ 2 pbNot yet observed!
~15%
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 39
Single Top ProductionSingle Top ProductionbtWqq * tqqb ' tWbg
s-channel t-channel Associated tW
Combine
(s+t)
Tevatron NLO 0.88 0.11 pb 1.98 0.25 pb ~ 0.1 pb
LHC NLO 10.6 1.1 pb 247 25 pb 62+17 -4 pb
CDF < 18 pb < 13 pb < 14 pb
D0 < 17 pb < 22 pb
B.W. Harris et al.:Phys.Rev.D66,054024 T.Tait: hep-ph/9909352
Z.Sullivan Phys.Rev.D70:114012 Belyaev,Boos: hep-ph/0003260
Run I
95% C.L.
(mtop=175 GeV/c2)
s-channel t-channel tW associated production
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 40
Single Top at the TevatronSingle Top at the Tevatron
The current CDF and DØ analyses not only provide drastically improved limits on the single top cross-section, but set all necessary tools and methods toward a possible discovery with a larger data sample!
Both collaborations are aggressively working on improving the results!
95% C.L. limits on single top cross-section
Single Top Discovery is Possible in Run 2 !!!!Single Top Discovery is Possible in Run 2 !!!!- R. Field (IMFP2006)- R. Field (IMFP2006)
ChannelChannel CDF (696 pbCDF (696 pb-1-1)) DØ (370 pbDØ (370 pb-1-1))
Combined 3.4 pb
s-channel 3.2 pb 5.0 pb
t-channel 3.1 pb 4.4 pb(2 pb)(2 pb)
(0.9 pb)(0.9 pb)
(2.9 pb)(2.9 pb)
Theory!
IMFP2006
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 41
Single Top ProductionSingle Top Production
First direct measurement of Vtb
0.68 <|Vtb|< 1 @ 95%CL or
|Vtb| = 1.3 ± 0.2
First direct measurement of Vtb
0.68 <|Vtb|< 1 @ 95%CL or
|Vtb| = 1.3 ± 0.2
s+t= 4.9 ±1.4 pb
s= 1.0, t =4.0 pb
s+t= 4.9 ±1.4 pb
s= 1.0, t =4.0 pb
Expected sensitivity: 2.1
PRL 98 18102 (2007)
Single Top Signal!
since IMFP2006
3.4!
DØ Combination3.6!
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 42
Single Top ProductionSingle Top Production
s+t= 3.0 ± 1.2 pb
s= 1.1, t =1.9 pb
s+t= 3.0 ± 1.2 pb
s= 1.1, t =1.9 pb
Expected sensitivity: 2.9Observed significance: 2.7
Expected sensitivity: 3.0
s+t= 2.7 ± 1.2 pb
s= 1.1, t =1.3 pb
s+t= 2.7 ± 1.2 pb
s= 1.1, t =1.3 pb
3.1!
since IMFP2006
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 43
Measurement of |VMeasurement of |Vtbtb| (CDF)| (CDF)CDF Run II Preliminary
L=1.5 fb-1
|Vtb|= 1.02 ± 0.18 (exp) ± 0.07(thy)|Vtb|= 1.02 ± 0.18 (exp) ± 0.07(thy)
t-channel
s-channel
Z. Sullivan, Phys.Rev. D70 (2004) 114012DØ |Vtb|>0.68, |Vtb| = 1.3 ±0.2
Using the Matrix Element cross section measurement, CDF determines |Vtb| assuming |Vtb| >> |Vts|, |Vtd|!
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 44
u d
Single Top Candidate EventSingle Top Candidate Event
EPD > 0.9EPD > 0.9
t-channel single top production has a kinematic peculiarity.
Distinct asymmetry in lepton charge Q times the pseudo-rapidity of the untagged jet!
Jet1
Jet2
Lepton
CDF Run: 211883, Event: 1911511
Central Electron CandidateCharge: -1, Eta=-0.72 MET=41.6 GeVJet1: Et=46.7 GeV Eta=-0.6 b-tag=1 Jet2: Et=16.6 GeV Eta=-2.9 b-tag=0Q× = 2.9 (t-channel signature)EPD=0.95
t-channelsingle top!
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 45
Single Top at the TevatronSingle Top at the Tevatron
Single top has (almost) been seen at the Tevatron at the expected rate!
Single top cross-section measurements!
ChannelChannel TheoryTheory CDF (1.5 fbCDF (1.5 fb-1-1)) DØ (0.9 fbDØ (0.9 fb-1-1))
Combined 2.9 pb 3.0 ± 1.2 pb 4.9 ± 1.4 pb
s-channel 0.9 pb ≈ 1.1 pb ≈ 1.0 pb
t-channel 2.0 pb ≈ 1.9 pb ≈ 4.0 pb
since IMFP2006
If you think 3.5 is enough to claim discovery?
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 46
Top-AntiTop ResonancesTop-AntiTop Resonances
CDF observed an intriguing excess of events with top-antitop invariant mass around 500 GeV!
Phys.Rev.Lett. 85, 2062 (2000)
CDF Run 1
Excess is reduced!
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 47
Top-AntiTop ResonancesTop-AntiTop Resonances The excess has disappeared!
Excess is gone!
since IMFP2006
IMFP2008 - Day 2 February 5, 2008
Rick Field – Florida/CDF/CMS Page 48
Tevatron MeasurementsTevatron MeasurementsJets
b-quarks
W
Z
W+
Z+
W+W
tt
W+Z
Z+Z
Single top
We are getting very close to the Higgs and/or new physics!