what a difference the last 2 years have made!

IFT - University of Florida February 29, 2008

Rick Field – Florida/CDF/CMS

What a Difference the Last 2 YearsWhat a Difference the Last 2 YearsHave Made!Have Made!

Rick FieldUniversity of Florida

(for the CDF & D0 Collaborations)

CDF Run 2

Palacio de Jabalquinto, Baeza, Spain

From IMFP2006 → IMFP2008

Physics at the Tevatron

Jet Physics, Heavy Quarks (b, t)Vector Bosons (, W, Z)

Happy Leap Year Day!



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!



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!



In Search of Rare ProcessesIn Search of Rare Processes

~9 orders of magnitude Higgs ED

PR

OD

UC

TIO

N C

RO

SS

SE

CT

ION

(fb

)

1 pb

We are beginning to measure cross-sections ≤ 1 pb!

W’, Z’, T’

We might get lucky!

(pT(jet) > 525 GeV) ≈ 15 fb!

15 fb



Jets at TevatronJets at Tevatron

Experimental Jets: The study of “real” jets requires a “jet algorithm” and the different algorithms correspond to different observables and give different results!

“Theory Jets”

Next-to-leading order parton level calculation

0, 1, 2, or 3 partons!

“Tevatron Jets”

Experimental Jets: The study of “real” jets requires a good understanding of the calorimeter response!

Experimental Jets: To compare with NLO parton level (and measure structure functions) requires a good understanding of the “underlying event”!



Jet CorrectionsJet CorrectionsCalorimeter Jets:

We measure “jets” at the “hadron level” in the calorimeter. We certainly want to correct the “jets” for the detector resolution and

effieciency. Also, we must correct the “jets” for “pile-up”. Must correct what we measure back to the true “particle level” jets!

Proton AntiProton

PT(hard)

Outgoing Parton

Outgoing Parton

Underlying Event Underlying Event

Initial-State Radiation

Final-State Radiation

Particle Level Jets: Do we want to make further model dependent corrections? Do we want to try and subtract the “underlying event” from the

“particle level” jets. This cannot really be done, but if you trust the Monte-Carlo

models modeling of the “underlying event” you can try and do it by using the Monte-Carlo models (use PYTHIA Tune A).

Parton Level Jets: Do we want to use our data to try and extrapolate back to the parton

level? This also cannot really be done, but again if you trust the Monte-

Carlo models you can try and do it by using the Monte-Carlo models.

The “underlying event” consists of hard initial & final-state radiation

plus the “beam-beam remnants” and possible multiple parton interactions.



Inclusive Jet Cross Section (CDF)Inclusive Jet Cross Section (CDF)

Run I CDF Inclusive Jet Data(Statistical Errors Only)JetClu RCONE=0.7 0.1<||<0.7R=F=ET /2 RSEP=1.3

CTEQ4M PDFsCTEQ4HJ PDFs

Run 1 showed a possible excess at large jet ET (see below).

This resulted in new PDF’s with more gluons at large x.

The Run 2 data are consistent with the new structure functions (CTEQ6.1M).

CTEQ4M

CTEQ4HJ

IMFP2006



Inclusive Jet Cross Section (CDF)Inclusive Jet Cross Section (CDF)

IMFP2006

MidPoint Cone Algorithm (R = 0.7, fmerge = 0.75)

Data corrected to the hadron level L = 1.04 fb-1

0.1 < |yjet| < 0.7

Compared with NLO QCD

Sensitive to UE + hadronization effects for PT < 200 GeV/c!

today 1.13 fb-1

(pT > 525 GeV) ≈ 15 fb!



KKTT Algorithm Algorithm

Proton AntiProton

PT(hard)

Outgoing Parton

Outgoing Parton




kT Algorithm: Cluster together calorimeter towers by their kT proximity. Infrared and collinear safe at all orders of pQCD. No splitting and merging. No ad hoc Rsep parameter necessary to compare with parton level. Every parton, particle, or tower is assigned to a “jet”. No biases from seed towers. Favored algorithm in e+e- annihilations!

For each precluster, calculate 2

,iTi pd

For each pair of preculsters, calculate

2

222

,2

,

)()(),min(

D

yyppd jiji

jTiTij

Find the minimum of all di and dij.

Move i to list of jets

no

yes

Begin

End

Minumum is dij?

Any Preclusters

left?

no

Merge i and j

yes

KT Algorithm

Only towers with ET > 0.5 GeV are shown

Raw Jet ET = 533 GeVRaw Jet ET = 618 GeV

Will the KT algorithm be effective in the collider

environment where there is an “underlying event”?

CDF Run 2



KKTT Inclusive Jet Cross Section (CDF) Inclusive Jet Cross Section (CDF)

KT Algorithm (D = 0.7)

Data corrected to the hadron level L = 385 pb-1

0.1 < |yjet| < 0.7

Compared with NLO QCD.

IMFP2006today 1.0 fb-1

Sensitive to UE + hadronization effects for PT < 200 GeV/c!



from Run I

High x Gluon PDFHigh x Gluon PDF Forward jets measurements put

constraints on the high x gluon distribution!

Uncertainty on gluon PDF (from CTEQ6)

x

Big uncertainty for high-x gluon PDF!

high x low x

Forward Jets



DiJet Cross Section (CDF)DiJet Cross Section (CDF) MidPoint Cone Algorithm (R

= 0.7, fmerge = 0.75)

Data corrected to the hadron level L = 1.13 fb-1

|yjet1,2| < 1.0


since IMFP2006

Sensitive to UE + hadronization effects!

CDF Run II Preliminary



Inclusive Jet versus DiJet (CDF)Inclusive Jet versus DiJet (CDF)


CTEQ6.1M = PT/2


CTEQ6.1M = mean(PT1,PT2)

Inclusive Jet (CDF) DiJet (CDF)



CDF DiJet Event: M(jj) CDF DiJet Event: M(jj) ≈ 1.4 TeV≈ 1.4 TeV

ETjet1 = 666 GeV ET

jet2 = 633 GeV Esum = 1,299 GeV M(jj) = 1,364 GeV

M(jj)/Ecm ≈ 70%!!

Exclusive p+p → p+p+e++e- (16 events) = 1.6 ± 0.3 pb

CDF Run II

since IMFP2006



-1 +1

2

0

Leading Jet

Toward Region

Transverse Region

Transverse Region

Away Region

Away Region

Jet #1 Direction

“Transverse” “Transverse”

“Toward”

“Away”

“Toward-Side” Jet

“Away-Side” Jet

““Towards”, “Away”, “Transverse”Towards”, “Away”, “Transverse”

Look at correlations in the azimuthal angle relative to the leading charged particle jet (|| < 1) or the leading calorimeter jet (|| < 2).

Define || < 60o as “Toward”, 60o < | < 120o as “Transverse ”, and || > 120o as “Away”. Each of the three regions have area = 2×120o = 4/3.

Jet #1 Direction

“Toward”


“Away”

Correlations relative to the leading jetCharged particles pT > 0.5 GeV/c || < 1Calorimeter towers ET > 0.1 GeV || < 1“Transverse” region is

very sensitive to the “underlying event”!

Look at the charged particle density, the

charged PTsum density and the ETsum density in

all 3 regions!



Jet #1 Direction

“Overall”

“Leading Jet”

Overall Totals (|Overall Totals (|| < 1)| < 1)

Data at 1.96 TeV on the overall number of charged particles (pT > 0.5 GeV/c, || < 1) and the overall scalar pT sum of charged particles (pT > 0.5 GeV/c, || < 1) and the overall scalar ET sum of all particles (|| < 1) for “leading jet” events as a function of the leading jet pT. The data are corrected to the particle level (with errors that include both the statistical error and the systematic uncertainty) and are compared with PYTHIA Tune A at the particle level (i.e. generator level)..

Overall Totals versus PT(jet#1)

1

10

100

1000

0 50 100 150 200 250 300 350 400

PT(jet#1) (GeV/c)

Av

era

ge

CDF Run 2 Preliminarydata corrected

pyA generator level

"Leading Jet"MidPoint R=0.7 |(jet#1)|<2

Charged Particles (||<1.0, PT>0.5 GeV/c)

Stable Particles (||<1.0, all PT)

ETsum (GeV)

PTsum (GeV/c)

Nchg

Nchg = 30

PTsum = 190 GeV/c

ETsum = 330 GeV

ETsum = 775 GeV!



Jet #1 Direction

“Toward”


“Away”

“Leading Jet”

““Towards”, “Away”, “Transverse”Towards”, “Away”, “Transverse”

Data at 1.96 TeV on the density of charged particles, dN/dd, with pT > 0.5 GeV/c and || < 1 for “leading jet” events as a function of the leading jet pT for the “toward”, “away”, and “transverse” regions. The data are corrected to the particle level (with errors that include both the statistical error and the systematic uncertainty) and are compared with PYTHIA Tune A at the particle level (i.e. generator level).

Charged Particle Density: dN/dd

0

1

2

3

4

5

0 50 100 150 200 250 300 350 400

PT(jet#1) (GeV/c)

Ave

rag

e C

har

ged

Den

sity


pyA generator level



"Away"

"Toward"

"Transverse"

Data at 1.96 TeV on the charged particle scalar pT sum density, dPT/dd, with pT > 0.5 GeV/c and || < 1 for “leading jet” events as a function of the leading jet pT for the “toward”, “away”, and “transverse” regions. The data are corrected to the particle level (with errors that include both the statistical error and the systematic uncertainty) and are compared with PYTHIA Tune A at the particle level (i.e. generator level).

Data at 1.96 TeV on the particle scalar ET sum density, dET/dd, for || < 1 for “leading jet” events as a function of the leading jet pT for the “toward”, “away”, and “transverse” regions. The data are corrected to the particle level (with errors that include both the statistical error and the systematic uncertainty) and are compared with PYTHIA Tune A at the particle level (i.e. generator level).

Factor of ~4.5

Charged PTsum Density: dPT/dd

0.1

1.0

10.0

100.0

0 50 100 150 200 250 300 350 400

PT(jet#1) (GeV/c)

Ch

arg

ed P

Tsu

m D

ensi

ty (

GeV

/c)


pyA generator level



"Toward""Away"

"Transverse"

Factor of ~16

ETsum Density: dET/dd

0.1

1.0

10.0

100.0

0 50 100 150 200 250 300 350 400

PT(jet#1) (GeV/c)

ET

sum

Den

sity

(G

eV)


pyA generator level


Stable Particles (||<1.0, all PT)

"Toward"

"Away"

"Transverse"

Factor of ~13



“Leading Jet”

The Leading Jet MassThe Leading Jet Mass

Data at 1.96 TeV on the leading jet invariant mass for “leading jet” events as a function of the leading jet pT. The data are corrected to the particle level (with errors that include both the statistical error and the systematic uncertainty) and are compared with PYTHIA Tune A and HERWIG (without MPI) at the particle level (i.e. generator level).

Shows the Data - Theory for the leading jet invariant mass for “leading jet” events as a function of the leading jet pT for PYTHIA Tune A and HERWIG (without MPI).

Leading Jet Invariant Mass

0

10

20

30

40

50

60

70

0 50 100 150 200 250 300 350 400

PT(jet#1) (GeV/c)

Jet

Mas

s (G

eV)



generator level theory

PY Tune A

HW

Leading Jet Invariant Mass

-4.0

0.0

4.0

8.0

12.0

0 50 100 150 200 250 300 350 400

PT(jet#1 uncorrected) (GeV/c)

Dat

a -

Th

eory

(G

eV)


generator level theory


HW PY Tune A

Off by ~2 GeV

Jet #1 Direction

“Toward”


“Away”



bb DiJet Cross Section (CDF)bb DiJet Cross Section (CDF)

b-quark tag based on displaced vertices. Secondary vertex mass discriminates flavor.

Require two secondary vertex tagged b-jets within |y|< 1.2 and study the two b-jets (Mjj, jj, etc.).

Collision point

≈ 85% purity!



The Sources of Heavy QuarksThe Sources of Heavy Quarks

We do not observe c or b quarks directly. We measure D-mesons (which contain a c-quark) or we measure B-mesons (which contain a b-quark) or we measure c-jets (jets containing a D-meson) or we measure b-jets (jets containing a B-meson).

Proton AntiProton

“Flavor Creation” Q-quark

Q-quark



Leading Order Matrix ElementsLeading-Log Order

QCD Monte-Carlo Model (LLMC)

Dbjpip FbkijdGGBd )()(

(structure functions) × (matrix elements) × (Fragmentation)

+ (initial and final-state radiation: LLA)



Other Sources of Heavy QuarksOther Sources of Heavy Quarks

In the leading-log order Monte-Carlo models (LLMC) the separation into “flavor creation”, “flavor excitation”, and “gluon splitting” is unambiguous, however at next to leading order the same amplitudes contribute to all three processes!

Next to Leading Order Matrix Elements

Proton AntiProton

“Flavor Excitation” Q-quark

gluon, quark, or antiquark



Q-quark

“Flavor Excitation” (LLMC) corresponds to the scattering of a b-quark (or bbar-quark) out of the initial-state into the final-state by a gluon or by a light quark or antiquark.

Proton AntiProton

“Gluon Splitting”

Q-quark



Q-quark

“Gluon-Splitting” (LLMC) is where a b-bbar pair is created within a parton shower or during the the fragmentation process of a gluon or a light quark or antiquark. Here the QCD hard 2-to-2 subprocess involves only gluons and light quarks and antiquarks.

g

g

g

Q

Q Amp (FC)

g

g

g

Q

Q

Amp (FE)

g

g

g

Q

Q

Amp (GS)

Amp(gg→QQg) = + +(gg→QQg) =

2and there are interference terms!



bb DiJet Cross Section (CDF)bb DiJet Cross Section (CDF) ET(b-jet#1) > 35 GeV, ET(b-jet#2) > 32

GeV, |(b-jets)| < 1.2.

Preliminary CDF Results:

bb = 34.5 1.8 10.5 nb

QCD Monte-Carlo Predictions:

PYTHIA Tune A CTEQ5L

38.7 ± 0.6 nb

HERWIG CTEQ5L 21.5 ± 0.7 nb

MC@NLO 28.5 ± 0.6 nb

MC@NLO + Jimmy 35.7 ± 2.0 nb

Differential Cross Section as a function of the b-bbar DiJet invariant mass!

Proton AntiProton

“Flavor Creation”

b-quark

b-quark




Adding multiple parton interactions (i.e. JIMMY) to enhance the “underlying event” increases the b-bbar jet cross section!

JIMMY: MPIJ. M. Butterworth

J. R. ForshawM. H. Seymour

JIMMYRuns with HERWIG and adds multiple parton interactions!

IMFP2006



bb DiJet Cross Section (CDF)bb DiJet Cross Section (CDF)

ET(b-jet#1) > 35 GeV, ET(b-jet#2) > 32 GeV, |(b-jets)| < 1.2.

Sensitive to the “underlying event”!

Preliminary CDF Results:

bb = 5664 168 1270 pb

QCD Monte-Carlo Predictions:

PYTHIA Tune A CTEQ5L

5136 ± 52 pb

HERWIG CTEQ5L+Jimmy

5296 ± 98 pb

MC@NLO+Jimmy 5421 ± 105 nb

Proton AntiProton

“Flavor Creation” b-quark

b-quark



SystematicUncertainty

Predominately Flavor creation!

since IMFP2006



bb DiJet bb DiJet Distribution (CDF) Distribution (CDF)

It takes NLO + “underlying event” to get it right!

Proton AntiProton

“Flavor Creation” b-quark

b-quark



b-jet direction

“Toward”

“Away”

bbar-jet

Large (i.e. b-jets are “back-to-back”) is predominately “flavor creation”.

Small (i.e. b-jets are near each other) is predominately “flavor excitation” and “gluon splitting”.

Proton AntiProton

“Gluon Splitting”

Q-quark



Q-quark

since IMFP2006



Z + b-Jet Production (CDFZ + b-Jet Production (CDF)) Important background for new physics!

)(0033.0)(0078.00237.0][

][

14.032.096.0)(

syststatjetZ

bjetZR

pbbjetZ

Extract fraction of b-tagged jets from secondary vertex mass distribution: NO assumption on the charm content.

L = 335 pb-1

Leptonic decays for the Z. Z associated with jets. CDF: JETCLU, D0: R = 0.7, |jet| < 1.5, ET >20 GeV

Look for tagged jets in Z events.

IMFP2006

Observable CDF Data PYTHIA Tune A MCFM NLO (+UE)

(Z+b-jet) 0.94±0.15±0.15 pb -- 0.51 (0.56) pb

(Z+b-jet)/(Z) 0.369±0.057±0.055 % 0.35% 0.21 (0.23) %

(Z+b-jet)/(Z+jet) 2.35±0.36±0.45 % 2.18% 1.88 (1.77) %

today 1.5 fb-1

Sensitive to the “underlying event”!

since IMFP2006



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



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



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!



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



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.



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



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



Higgs Higgs → → Search (CDF) Search (CDF)events events

No Significant Excess of events above SM background is observed!

since IMFP2006



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



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!



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



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



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



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



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



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



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



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



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!



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



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



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



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



Higgs Higgs → W+W→ W+W We are within a factor of two of

the standard model Higgs (160 GeV) → WW!

since IMFP2006



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



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



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



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



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



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



Top Quark MassTop Quark Mass

Dilepton Channel

since IMFP2006

Mt=170.4 ± 3.1(stat) ± 3.0(sys)GeV/c2

Leptons+Jets Channel



Top Cross-Section vs MassTop Cross-Section vs Mass

Tevatron Summer 2005 CDF Winter 2006

Cacciari, Mangano, et al., hep-ph/0303085

CDF combined



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!


Rick Field – Florida/CDF/CMS Page 62

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%



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



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



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!



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



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|!



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!



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?



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!



Top-AntiTop ResonancesTop-AntiTop Resonances The excess has disappeared!

Excess is gone!

since IMFP2006



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!

what a difference the last 2 years have made!

Documents