What a Difference the Last 2 Years Have Made!

1
What a Difference the Last 2 YearsHave Made!
From IMFP2006 ? IMFP2008
Rick Field University of Florida (for the CDF
D0 Collaborations)
Jet Physics, Heavy Quarks (b, t) Vector Bosons
(g, W, Z)
Palacio de Jabalquinto, Baeza, Spain
Happy Leap Year Day!
CDF Run 2
2
Tevatron Performance
The data collected since IMFP 2006 more than
doubled the total data collected in Run 2!
IMFP 2008 3.3 fb-1 delivered 2.8 fb-1 recorded
1.6 fb-1
IMFP 2006 1.5 fb-1 delivered 1.2 fb-1 recorded
Integrated Luminosity per Year

• Luminosity records (IMFP 2008)
• Highest Initial Inst. Lum 2.921032 cm-2s-1
• Integrated luminosity/week 45 pb-1
• Integrated luminosity/month 165 pb-1

• Luminosity Records (IMFP 2006)
• Highest Initial Inst. Lum 1.81032 cm-2s-1
• Integrated luminosity/week 25 pb-1
• Integrated luminosity/month 92 pb-1

3
Many New Tevatron Results!
Some of the CDF Results since IMFP2006
I cannot possibility cover all the great physics
results from the Tevatron since IMFP 2006!

• Observation of Bs-mixing ?ms 17.77 0.10
  (stat) 0.07(sys).
• Observation of new baryon states Sb and Xb.
• 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) s 5.0 (1.7) pb.
• ZZ evidence (3-sigma).
• Single Top evidence (3-sigma) with 1.5 fb-1 s
  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.

I will show a few of the results!
4
In Search of Rare Processes
We might get lucky!
We are beginning to measure cross-sections 1 pb!
s(pT(jet) gt 525 GeV) 15 fb!
PRODUCTION CROSS SECTION (fb)
1 pb
W, Z, T
15 fb
5
Jets at Tevatron
Next-to-leading order parton level calculation 0,
1, 2, or 3 partons!

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

• 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!

6
Jet Corrections

• Calorimeter 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!

• 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.
7
Inclusive Jet Cross Section (CDF)

• Run 1 showed a possible excess at large jet ET
  (see below).
• This resulted in new PDFs with more gluons at
  large x.
• The Run 2 data are consistent with the new
  structure functions (CTEQ6.1M).

IMFP2006
8
Inclusive Jet Cross Section (CDF)

• MidPoint Cone Algorithm (R 0.7,
  fmerge 0.75)
• Data corrected to the hadron level
• L 1.04 fb-1
• 0.1 lt yjet lt 0.7
• Compared with NLO QCD

IMFP2006
today
1.13 fb-1
s(pT gt 525 GeV) 15 fb!
Sensitive to UE hadronization effects for PT lt
200 GeV/c!
9
KT Algorithm

• 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 ee- annihilations!

KT Algorithm
Will the KT algorithm be effective in the
collider environment where there is an
underlying event?
Raw Jet ET 533 GeV
Raw Jet ET 618 GeV
CDF Run 2
Only towers with ET gt 0.5 GeV are shown
10
KT Inclusive Jet Cross Section (CDF)

• KT Algorithm (D 0.7)
• Data corrected to the hadron level
• L 385 pb-1
• 0.1 lt yjet lt 0.7
• Compared with NLO QCD.

IMFP2006
today
1.0 fb-1
Sensitive to UE hadronization effects for PT lt
200 GeV/c!
11
High x Gluon PDF

• Forward jets measurements put constraints on the
  high x gluon distribution!

Big uncertainty for high-x gluon PDF!
Uncertainty on gluon PDF (from CTEQ6)
x
Forward Jets
high x
low x
12
KT Forward Jet Cross Section (CDF)

• KT Algorithm (D 0.7).
• Data corrected to the hadron level.
• L 385 pb-1.
• Five rapidity regions
• yjet lt 0.1
• 0.1 lt yjet lt 0.7
• 0.7 lt yjet lt 1.1
• 1.1 lt yjet lt 1.6
• 1.6 lt yjet lt 2.1
• Compared with NLO QCD

today
1.0 fb-1
IMFP2006
13
Forward Jet Cross Section (CDF)

• MidPoint Cone Algorithm (R 0.7,
  fmerge 0.75)
• Data corrected to the hadron level
• L 1.13 pb-1.
• Five rapidity regions
• yjet lt 0.1
• 0.1 lt yjet lt 0.7
• 0.7 lt yjet lt 1.1
• 1.1 lt yjet lt 1.6
• 1.6 lt yjet lt 2.1
• Compared with NLO QCD

1.0 fb-1
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DiJet Cross Section (CDF)
CDF Run II Preliminary

• MidPoint Cone Algorithm (R 0.7,
  fmerge 0.75)
• Data corrected to the hadron level
• L 1.13 fb-1
• yjet1,2 lt 1.0
• Compared with NLO QCD

Sensitive to UE hadronization effects!
15
Inclusive Jet versus DiJet (CDF)
Inclusive Jet (CDF)
DiJet (CDF)

• MidPoint Cone Algorithm (R 0.7, fmerge
  0.75)
• CTEQ6.1M m PT/2

• MidPoint Cone Algorithm (R 0.7, fmerge
  0.75)
• CTEQ6.1M m mean(PT1,PT2)

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CDF DiJet Event M(jj) 1.4 TeV
ETjet1 666 GeV ETjet2 633 GeV Esum 1,299
GeV M(jj) 1,364 GeV
Exclusive pp ? ppee- (16 events) s 1.6
0.3 pb
M(jj)/Ecm 70!!
CDF Run II
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Towards, Away, Transverse
Look at the charged particle density, the charged
PTsum density and the ETsum density in all 3
regions!
Df Correlations relative to the leading
jet Charged particles pT gt 0.5 GeV/c h lt
1 Calorimeter towers ET gt 0.1 GeV h lt 1
Transverse region is very sensitive to the
underlying event!

• Look at correlations in the azimuthal angle Df
  relative to the leading charged particle jet (h
  lt 1) or the leading calorimeter jet (h lt 2).
• Define Df lt 60o as Toward, 60o lt Df lt 120o
  as Transverse , and Df gt 120o as Away.
  Each of the three regions have area DhDf 2120o
  4p/3.

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Overall Totals (h lt 1)
ETsum 775 GeV!
Leading Jet
ETsum 330 GeV
PTsum 190 GeV/c
Nchg 30

• Data at 1.96 TeV on the overall number of charged
  particles (pT gt 0.5 GeV/c, h lt 1) and the
  overall scalar pT sum of charged particles (pT gt
  0.5 GeV/c, h lt 1) and the overall scalar ET sum
  of all particles (h lt 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)..

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Towards, Away, Transverse
Leading Jet
Factor of 13
Factor of 16
Factor of 4.5

• Data at 1.96 TeV on the density of charged
  particles, dN/dhdf, with pT gt 0.5 GeV/c and h lt
  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 charged particle scalar
  pT sum density, dPT/dhdf, with pT gt 0.5 GeV/c and
  h lt 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/dhdf, for h lt 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).

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The Leading Jet Mass
Leading Jet
Off by 2 GeV

• 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).

• 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).

21
bb DiJet Cross Section (CDF)
85 purity!
Collision point

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

• Require two secondary vertex tagged b-jets within
  ylt 1.2 and study the two b-jets (Mjj, Dfjj,
  etc.).

22
The Sources of Heavy Quarks
Leading-Log Order QCD Monte-Carlo Model (LLMC)
Leading Order Matrix Elements

• 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).

(structure functions)
(matrix elements)
(Fragmentation)
(initial and final-state radiation LLA)
23
Other Sources of Heavy Quarks
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.
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.

• 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!

and there are interference terms!
Next to Leading Order Matrix Elements
2


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bb DiJet Cross Section (CDF)
IMFP2006

• ET(b-jet1) gt 35 GeV, ET(b-jet2) gt 32 GeV,
  h(b-jets) lt 1.2.

Preliminary CDF Results
sbb 34.5 ? 1.8 ? 10.5 nb
QCD Monte-Carlo Predictions
Differential Cross Section as a function of the
b-bbar DiJet invariant mass!
JIMMY Runs with HERWIG and adds multiple parton
interactions!
JIMMY MPI J. M. Butterworth J. R. Forshaw M. H.
Seymour
Adding multiple parton interactions (i.e. JIMMY)
to enhance the underlying event increases the
b-bbar jet cross section!
25
bb DiJet Cross Section (CDF)

• ET(b-jet1) gt 35 GeV,
  ET(b-jet2) gt 32 GeV, h(b-jets) lt 1.2.

Systematic Uncertainty
Preliminary CDF Results
sbb 5664 ? 168 ? 1270 pb
QCD Monte-Carlo Predictions
Predominately Flavor creation!
Sensitive to the underlying event!
26
bb DiJet Df Distribution (CDF)

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

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

• It takes NLO underlying event to get it right!

27
Z b-Jet Production (CDF)
IMFP2006

• Important background for new physics!

• Leptonic decays for the Z.
• Z associated with jets.
• CDF JETCLU, D0
• R 0.7, hjet lt 1.5, ET gt20 GeV
• Look for tagged jets in Z events.

1.5 fb-1
L 335 pb-1
today
Extract fraction of b-tagged jets from secondary
vertex mass distribution NO assumption on the
charm content.
Sensitive to the underlying event!
28
Z-boson Cross Section (CDF)
L 72 pb-1
IMFP2006
QCD Drell-Yan

• Impressive agreement between experiment and NNLO
  theory (Stirling, van Neerven)!

29
Z-boson Cross Section (CDF)
IMFP2006
L 337 pb-1

• Impressive agreement between experiment and NNLO
  theory (Stirling, van Neerven)!

30
Z-Boson Rapidity Distribution

• Measure ds/dy for Z?ee-. 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 PDFs.
• Plug-plug electrons, ZPP, are used to probe the
  high x region!

Plug-Plug electrons!
1.1fb-1 91,362 events 66 lt MZ lt 116 GeV
31
Z-Boson Rapidity Distribution

• CDF measured ds/dy for Z/g compared with an NL0
  calculation using CTEQ6.1M PDF.
• The NLO theory is scaled to the measured s(Z)!
• No PDF or luminosity uncertainties included.

NLO CTEQ6.1 PDF
NLO MRST PDF
NLL0 NNL0 MRST PDF
32
The Z?tt Cross Section (CDF)

• Taus are difficult to reconstruct at hadron
  colliders
• Exploit event topology to suppress backgrounds
  (QCD Wjet).
• Measurement of cross section important for Higgs
  and SUSY analyses.
• CDF strategy of hadronic t reconstruction
• Study charged tracks define signal and isolation
  cone (isolation require no tracks in isolation
  cone).
• Use hadronic calorimeter clusters (to suppress
  electron background).
• p0 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?tt electron isolated track
• One t decays to an electron t?eX (ET(e) gt 10
  GeV) .
• One t decays to hadrons t ? hX (pT gt 15GeV/c).
• Remove Drell-Yan ee- and apply event topology
  cuts for non-Z background.

33
The Z?tt Cross Section (CDF)

• CDF Z?tt (350 pb-1) 316 Z?tt candidates.
• Novel method for background estimation main
  contribution QCD.
• t identification efficiency 60 with
  uncertainty about 3!

IMFP2006
264 23 (stat) 14 (sys) 15 (lum)
34
Higgs ? tt Search (CDF)
events
140 GeV Higgs Signal!
IMFP2006
1 event

• Data mass distribution agrees with SM
  expectation
• MH gt 120 GeV 8.40.9 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.

35
Higgs ? tt Search (CDF)
events
events
No Significant Excess of events above SM
background is observed!
36
W-boson Cross Section (CDF)
W Acceptance

• Extend electron coverage to the forward region
  (1.2 lt h lt 2.8)!

IMFP2006
48,144 W candidates 4.5 background overall
efficiency of signal 7
37
W-Boson Mass Measurement

• The 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
Single most precise measurement to date!
38
W-Boson Width Measurement

• Model 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.

39
W Production Charge Asymmetry

• 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 PDFs!

Q2 100 GeV2 MRST2004NLO
xG(x,Q2)
u
d
d
u
x
u
10-3 10-2 10-1 1
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W Production Charge Asymmetry

• Since the longitudinal momentum of the neutrino,
  pL(n), 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?en channel.
• pL(n) 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,
  s(yW).
• The process is iterated since s(yW) depends on
  the asymmetry.

41
W g Cross Sections (CDF)
IMFP2006
ET(g) gt 7 GeV R(lg) gt 0.7
42
W g Cross Sections (CDF)
ET(g) gt 7 GeV R(lg) gt 0.7
18.030.65(stat)2.55(sys) 1.05(lum)
43
Z g Cross Sections (CDF)
IMFP2006
Note ?(W?)/?(Z?) 4 while ?(W)/?(Z) 11
ET(g) gt 7 GeV R(lg) gt 0.7
44
Z g Cross Sections (CDF)
390 events
ET(g) gt 7 GeV R(lg) gt 0.7 Meeg gt 40 GeV/c2
45
The WW Cross-Section
IMFP2006
Campbell Ellis 1999
46
The WW Cross-Section (CDF)
IMFP2006
L 825 pb-1
We are beginning to study the details
of Di-Boson production at the Tevatron!

• WW?dileptons MET
• Two leptons pT gt 20 GeV/c.
• Z veto.
• MET gt 20 GeV.
• Zero jets with ETgt15 GeV and hlt2.5.

Observe 95 events with 37.2 background!
Lepton-Pair Mass!
Missing ET!
ET Sum!
47
WWWZ Cross-Section
NLO Theory sWW Br(W?ln, W?jj) 12.4 pb 0.146
1.81 pb sWZ Br(W?ln, Z?jj) 3.96 pb 0.07
0.28 pb
48
The ZW, ZZ Cross Sections
IMFP2006
Observe 2 events with a background of 0.90.2!
Upper Limits
49
The WZ Cross Section

• Strategy
• Search for events with 3 leptons and missing
  energy.
• Small cross-section but very clean signal.
• Anomalous cross-section sensitive to non SM
  contributions.

3.0 s significance!
50
The ZZ Cross Section

• Strategy
• 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 llnn signal.

ZZ decaying into 4 leptons
ZZ decaying into 2 leptons MET
3.0 s significance!
51
Higgs ? WW

• We are within a factor of two of the standard
  model Higgs (160 GeV) ? WW!

52
Heavy Quark Production at the Tevatron

• Total inelastic stot 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 , lc , cc , Xc, etc.
• Want to studey the production of B-mesons
  and baryons Bu , Bd , Bs , Bc , lb , Xb, etc.

with 1 fb-1 1.4 x 1014 1 x 1011 6 x
106 6 x 105 14,000 5,000

• Two Heavy Quark Triggers at CDF
• For semileptonic decays we trigger on m and e.
• For hadronic decays we trigger on one or more
  displaced tracks (i.e. large impact parameter).

CDF-SVT
53
B-Baryon Observations (CDF)
The Tevatron is excellent at producing particles
containing b and c quarks(Bu, Bd, Bs, Bc,
?b, ?b,?b)
?b
?b
bc
54
Top Decay Channels

• mtgtmWmb so dominant decay t?Wb.
• The top decays before it hadronizes.
• B(W ? qq) 67.
• B(W ? ln) 11 l e, m, t.

55
Dilepton Channel (CDF)

• Selection
• 2 leptons ET gt 20 GeV with opposite sign.
• gt2 jets ET gt 15 GeV.
• Missing ET gt 25 GeV (and away from any jet).
• HTpTlepETjetMET gt 200 GeV.
• Z rejection.

• Backgrounds
• Physics Drell-Yan, WW/WZ/ZZ, Z ? tt
• Instrumental fake lepton

IMFP2006
84 events
65 events
20 events background
56
LeptonJets Channel (CDF)
b-Tagging

• Require b-jet to be tagged for discrimination.

Tagging efficiency for b jets50
for c jets10 for light q jets lt
0.1
1 b tag
IMFP2006
2 b tags
70 events
HTgt200GeV
180 events
150 events
45 events
Small background!
57
Tevatron Top-Pair Cross Section
CDF Run 2 Preliminary
Theory
Bonciani et al., Nucl. Phys. B529, 424
(1998) Kidonakis and Vogt, Phys. Rev. D68, 114014
(2003)
58
Top Quark Mass
Dilepton Channel
LeptonsJets Channel
Mt170.4 3.1(stat) 3.0(sys)GeV/c2
59
Top Cross-Section vs Mass
Tevatron Summer 2005
CDF Winter 2006
CDF combined
Cacciari, Mangano, et al., hep-ph/0303085
60
Constraining 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!

Summer 05
114 GeV Higgs very interesting for the Tevatron!
61
Top Charge, Branching, Lifetime, W Helicity
Top Charge
Top Lifetime
CDF Prelim. 318 pb-1
DØ Prelim. 365 pb-1
Everything consistent with the Standard Model!
?toplt 1.75x10-13s c?toplt 52.5?m at 95CL
Exclude Q 4/3 at 94 CL
Reconstructed Top Charge (e)
Impact Parameter (?m)
370 pb-1
f (DØ combined) 0.04 0.11(stat)
0.06(syst) f (SM pred.) 0
SM
signal
signalbgrnd
bgrnd
hep-ex/0603002
62
Other Sources of Top Quarks

• Dominant production mode ?NLONLL 6.7 ? 1.2 pb
• Relatively clean signature
• Discovery in 1995

85
15
ElectroWeak Production Single Top

• Larger background
• Smaller cross section s 2 pb
• Not yet observed!

63
Single Top Production
tW associated production
s-channel
t-channel
(mtop175 GeV/c2)
Run I 95 C.L.
B.W. Harris et al.Phys.Rev.D66,054024
T.Tait hep-ph/9909352 Z.Sullivan
Phys.Rev.D70114012 Belyaev,Boos
hep-ph/0003260
64
Single Top at the Tevatron
95 C.L. limits on single top cross-section
IMFP2006
(2.9 pb)
(0.9 pb)
(2 pb)

• 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!

Theory!
Single Top Discovery is Possible in Run 2 !!!! -
R. Field (IMFP2006)
65
Single Top Production
DØ Combination 3.6s!
Single Top Signal!
3.4s!
Expected sensitivity 2.1?
?st 4.9 1.4 pb ?s 1.0, ?t 4.0 pb
First direct measurement of Vtb 0.68 ltVtblt 1 _at_
95CL or Vtb 1.3 0.2
PRL 98 18102 (2007)
66
Single Top Production
3.1s!
?st 3.0 1.2 pb ?s 1.1, ?t 1.9 pb
?st 2.7 1.2 pb ?s 1.1, ?t 1.3 pb
Expected sensitivity 3.0?
Expected sensitivity 2.9? Observed significance
2.7?
67
Measurement of Vtb (CDF)

• Using the Matrix Element cross section
  measurement, CDF determines Vtb assuming Vtb
  gtgt Vts, Vtd!

Vtb 1.02 0.18 (exp) 0.07(thy)
DØ Vtbgt0.68, Vtb 1.3 0.2
68
Single Top Candidate Event

• t-channel single top production has a kinematic
  peculiarity.
• Distinct asymmetry in lepton charge Q times the
  pseudo-rapidity of the untagged jet!

t-channel single top!
EPD gt 0.9
Central Electron Candidate Charge -1, Eta-0.72
MET41.6 GeV Jet1 Et46.7 GeV Eta-0.6
b-tag1 Jet2 Et16.6 GeV Eta-2.9
b-tag0 Qh 2.9 (t-channel signature) EPD0.95
CDF Run 211883, Event 1911511
69
Single Top at the Tevatron
Single top cross-section measurements!

• Single top has (almost) been seen at the Tevatron
  at the expected rate!

If you think 3.5s is enough to claim discovery?
70
Top-AntiTop Resonances
CDF Run 1
Excess is reduced!
Phys.Rev.Lett. 85, 2062 (2000)

• CDF observed an intriguing excess of events with
  top-antitop invariant mass around 500 GeV!

71
Top-AntiTop Resonances

• The excess has disappeared!

Excess is gone!
72
Tevatron Measurements
Jets
b-quarks
We are getting very close to the Higgs and/or new
physics!
W
Z
Wg
Single top
Zg
WW
tt
WZ
ZZ