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!