XXXIV International Meeting on
Fundamental Physics
From HERA and the TEVATRON
to the LHC
Physics at the Tevatron
Rick Field
University of Florida
(for the CDF & D0 Collaborations)
Real Colegio Maria Cristina, El Escorial, Spain
CDF Run 2
IMFP2006 - Day 2
April 4, 2006
2nd Lecture
Heavy Quark Physics at the Tevatron
Rick Field – Florida/CDF/CMS
Page 1
Heavy Quark Physics at the Tevatron
 Charm Production at the Tevatron.
 J/Y and Bottom Production at the
Tevatron.
b-jet
c-quark
b-quark
t-quark
b-quark
 Top Production at the Tevatron.
Beam-Beam Remnants
proton
Antiproton
1.96
TeV
b-jet
Charm
b-hadron
J/Y
Top
Pair
Single
Top
uud
uud
b-jet
IMFP2006 - Day 2
April 4, 2006
Rick Field – Florida/CDF/CMS
Beam-Beam Remnants
t-quark
c-quark
b-quark
J/Y
Page 2
Heavy Quark Production at the Tevatron
with 1 fb-1
~1.4 x 1014
~1 x 1011
~6 x 106
~6 x 105
~14,000
~5,000
 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.
 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
IMFP2006 - Day 2
April 4, 2006
Rick Field – Florida/CDF/CMS
Page 3
Selecting Heavy Flavor Decays
 To select charm and beauty in an hadronic
environment requires:
•
•
High resolution tracking
A way to trigger on the hadronic decays (i.e. a
way to trigger on tracks)
 At CDF we have a “Secondary Vertex
Trigger” (the SVT).
CDF
The CDF Secondary Vertex Trigger (SVT)
•Online (L2) selection of displaced tracks based on Silicon detector hits.
Lxy ~ 1 mm
B/D decay
Primary Vertex
Collision Point
Secondary Vertex
D0 K
Impact Parameter ( ~100mm)
IMFP2006 - Day 2
April 4, 2006
Rick Field – Florida/CDF/CMS
Page 4
Selecting Prompt Charm Production
Collision Point
Prompt D
Secondary D from B
 Separate prompt (i.e. direct) and
secondary charm based on their transverse
impact parameter distribution.
 Prompt D-meson decays point back to
primary vertex (i.e. the collision point).
 Secondary D-meson decays do not point
back to the primary vertex.
Prompt
peak
Direct Charm Meson Fractions:
BD tail
D impact parameter
D0: fD=86.4±0.4±3.5%
D*+: fD=88.1±1.1±3.9%
D+: fD=89.1±0.4±2.8%
D+s: fD=77.3±3.8±2.1%
Most of reconstructed D
mesons are prompt!
IMFP2006 - Day 2
April 4, 2006
Rick Field – Florida/CDF/CMS
Page 5
Prompt Charm Meson Production
Charm Meson PT Distributions
CDF prompt charm cross section result published in PRL (hep-ex/0307080)
s ( D 0 , pT  5.5GeV, | Y | 1)  13.3  0.2  1.5mb  Theory calculation from M. Cacciari and P.
Nason: Resummed perturbative QCD
s ( D * , pT  6GeV, | Y | 1)  5.2  0.1  0.8mb
(FONLL), JHEP 0309,006 (2003).
s ( D  , pT  6GeV, | Y | 1)  4.3  0.1  0.7 mb
Fragmentation: ALEPH measurement,

s ( Ds , pT  8GeV, | Y | 1)  0.75  0.05  0.22 mb CTEQ6M PDF.
Data collected by SVT trigger from 2/2002-3/2002
L = 5.8±0.3 pb-1.
IMFP2006 - Day 2
April 4, 2006
Rick Field – Florida/CDF/CMS
Page 6
Comparisons with Theory
Ratio of Data to Theory
Next step is to study charm-anticharm correlations
to learn about the contributions from different
production mechanisms:
“flavor creation”
“flavor Excitation”
“gluon splitting”
 NLO calculations compatible within errors?
 The pT shapes are consistent with the theory for the D mesons,
but the measured cross section are a factor of about ~1.5 higher!
IMFP2006 - Day 2
April 4, 2006
Rick Field – Florida/CDF/CMS
Page 7
Bottom Quark Production at the Tevatron
Tevatron Run 1 b-Quark Cross Section
 Important to have good leading (or leading-log)
order QCD Monte-Carlo model predictions of
collider observables.
 The leading-log QCD Monte-Carlo model
estimates are the “base line” from which all other
calculations can be compared.
 If the leading-log order estimates are within a
factor of two of the data, higher order
calculations might be expected to improve the
agreement.
 If a leading-log order estimate is off by more than
a factor of two, it usually means that one has
overlooked something.
 I see no reason why the QCD Monte-Carlo
models should not qualitatively describe heavy
quark production (in the same way they
qualitatively describe light quark and gluon
production).
Integrated b-quark Cross Section for PT > PTmin
1.0E+01
1.8 TeV
|y| < 1
1.0E+00
Cross Section (mb)
CDF Run 1 1999
CTEQ3L
1.0E-01
Pythia Creation
Herwig Creation
D0 Data
CDF Data
1.0E-03
5
10
15
20
25
30
35
40
PTmin (GeV/c)
QCD Monte-Carlo
leading order “Flavor
Creation” is a factor of
four below the data!
 “Something is goofy” (Rick Field, CDF B
Group Talk, December 3, 1999).
IMFP2006 - Day 2
April 4, 2006
Isajet Creation
1.0E-02
Rick Field – Florida/CDF/CMS
Extrapolation of what
is measured (i.e. Bmesons) to the parton
level (i.e. b-quark)!
Page 8
The Sources of Heavy Quarks
Leading-Log Order
QCD Monte-Carlo Model (LLMC)
“Flavor Creation”
Proton
Leading Order Matrix Elements
Q-quark
AntiProton
Underlying Event
Underlying Event
Initial-State
Radiation
Q-quark
 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).
ds ( B)  G pi  G p  j  ds (ij  bk )  Fb D
(structure functions) × (matrix elements) × (Fragmentation)
+ (initial and final-state radiation: LLA)
IMFP2006 - Day 2
April 4, 2006
Rick Field – Florida/CDF/CMS
Page 9
Other Sources of Heavy Quarks
“Flavor Excitation”
“Gluon Splitting”
Q-quark
Proton
Proton
AntiProton
Underlying Event
AntiProton
Underlying Event
Underlying Event
Q-quark
Underlying Event
Initial-State
Radiation
Initial-State
Radiation
gluon, quark,
or antiquark
Q-quark
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.
“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 2to-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
Q
g
Amp(gg→QQg)
s(gg→QQg)
= =
g
+
Amp (FC)
Q
g
IMFP2006 - Day 2
April 4, 2006
Q
g
g
Q
g
Q
+
g
Q
Amp (FE)
Rick Field – Florida/CDF/CMS
g
Amp (GS)
g
Page 10
2
Inclusive b-quark Cross Section
Tevatron Run 1 b-Quark Cross Section
Integrated b-quark Cross Section for PT > PTmin
Total
1.0E+02
“Flavor Excitation”
PYTHIA 6.158
CTEQ3L PARP(67)=4
PY 6.158 (67=4) Total
Flavor Creation
Flavor Excitation
1.0E+01
“Flavor Creation”
Cross Section (mb)
Shower/Fragmentation
D0 Data
CDF Data
1.0E+00
1.0E-01
1.8 TeV
|y| < 1
1.0E-02
“Gluon Splitting”
1.0E-03
0
5
10
15
20
25
30
35
40
PTmin (GeV/c)

Data on the integrated b-quark total cross section (PT > PTmin, |y| < 1) for proton-antiproton
collisions at 1.8 TeV compared with the QCD Monte-Carlo model predictions of PYTHIA
6.158 (CTEQ3L, PARP(67)=4). The four curves correspond to the contribution from “flavor
creation”, “flavor excitation”, “gluon splitting”, and the resulting total.
IMFP2006 - Day 2
April 4, 2006
Rick Field – Florida/CDF/CMS
Page 11
Conclusions from Run 1
“Flavor Creation”
Proton
“Flavor Excitation”
b-quark
AntiProton
Underlying Event
Underlying Event
Initial-State
Radiation
b-quark
Proton
“Gluon Splitting”
b-quark
AntiProton
Underlying Event
Underlying Event
b-quark
Initial-State
Radiation
Proton
AntiProton
Underlying Event
Underlying Event
Initial-State
Radiation
gluon, quark,
or antiquark
Q-quark
Q-quark
All three sources are important at the Tevatron!




All three sources are important at the Tevatron and the QCD leading-log Monte-Carlo models do a fairly
good job in describing the majority of the b-quark data at the Tevatron.
We should be able experimentally to isolate
the individual
Rick Field,
Cambridgecontributions
Workshop, to b-quark production by
studying b-bbar correlations find out in much greater
July 18,detail
2002how well the QCD Monte-Carlo models
actually describe the data.
MC@NLO!
One has to be very careful when the experimenters extrapolate to the parton level and publish
parton
level results. The parton level is not an observable! Experiments measure hadrons! To extrapolate to the
parton level requires making additional assumptions that may or may not be correct (and often the
assumptions are not clearly stated or are very complicated). It is important that the experimenters
always publish the corresponding hadron level result along with their parton level extrapolation.
One also has to be very careful when theorists attempt to compare parton level calculations with
experimental data. Hadronization and initial/final-state radiation effects are almost always important
and theorists should embed their parton level results within a parton-shower/hadronization framework
(e.g. HERWIG or PYTHIA).
“Nothing is goofy”
IMFP2006 - Day 2
April 4, 2006
Rick Field – Florida/CDF/CMS
Page 12
PT Asymmetry
A=(PT1-PT2)/(PT1+PT2)
PT1 (b-quark)
b-quark Correlations: PT Asymmetry

A=(PT1-PT2“Flavor
)/(PT1+PT2Creation”
)
8
PT1 (b-quark)

Pythia CTEQ4L
7
ds/dA (mb)
5
4
3
“Away”
2
“Away”
1
PT2 (b-quark)
0
-1.0
PT2 (b-quark)
-0.8
“Gluon Splitting”
-0.6
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
A=(PT1-PT2)/(PT1+PT2)
Pythia Total

1.8 TeV
PT1 > 0 GeV/c
PT2 > 5 GeV/c
|y1| < 1 |y2| < 1
“Toward”
6
“Toward”
“Flavor Excitation”
Flavor Creation
Flavor Excitation
Shower/Fragmentation
Predictions of PYTHIA 6.158 (CTEQ4L, PARP(67)=1) for the asymmetry A = (PT1-PT2)/(PT1+PT2)
for events with a b-quark with PT1 > 0 GeV/c and |y1| < 1.0 and a bbar quark with PT2 > 5 GeV/c
and |y2| < 1.0 in proton-antiproton collisions at 1.8 TeV. The curves correspond to ds/dA (mb) for
flavor creation, flavor excitation, shower/fragmentation, and the resulting total.
IMFP2006 - Day 2
April 4, 2006
Rick Field – Florida/CDF/CMS
Page 13
Distance R in h- Space
“Gluon Splitting”
b-quark Correlations: Distance R
b-quark Correlations: Distance R
10.0
1.000
Pythia Total
Pythia CTEQ4L
Flavor Creation
Flavor Excitation
Flavor Creation
Flavor Excitation
Shower/Fragmentation
ds/dR (mb)
ds/dR (mb)
Shower/Fragmentation
1.0
0.1
1.8 TeV
PT1 > 12 GeV/c
PT2 > 6 GeV/c
|y1| < 1 |y2| < 1
0.100
0.010
0.001
0
1
2
3
4
5
0
Distance R
h- Space
+1
b-quark
R
h
b-quark
-1
Pythia CTEQ4L
Pythia Total
1.8 TeV
PT1 > 5 GeV/c
PT2 > 0 GeV/c
|y1| < 1 |y2| < 1
0
IMFP2006 - Day 2
April 4, 2006

1
2
3
4
5
Distance R
 Predictions of PYTHIA 6.158 (CTEQ4L, PARP(67)=1)
for the distance, R, in h- space between the b and
bbar-quark with |y1|<1 and |y2|<1 in proton-antiproton
collisions at 1.8 TeV. The curves correspond to ds/dR
(mb) for flavor creation, flavor excitation,
shower/fragmentation, and the resulting total.
2
Rick Field – Florida/CDF/CMS
Page 15
Azimuthal Correlations
“Flavor Creation”
New PYTHIA default
(less initial-state radiation)
“Flavor Excitation”
b-quark Correlations: Azimuthal  Distribution
b-quark Correlations: Azimuthal  Distribution
0.01000
0.01000
1.8 TeV
PT1 > 15 GeV/c
PT2 > 10 GeV/c
|y1| < 1 |y2| < 1
1.8 TeV
PT1 > 15 GeV/c
PT2 > 10 GeV/c
|y1| < 1 |y2| < 1
PYTHIA 6.206
CTEQ5L PARP(67)=1
ds/d (mb/deg)
ds/d (mb/deg)
Old PYTHIA default
(more initial-state radiation)
0.00100
0.00010
0.00100
0.00010
"Away"
"Toward"
"Away"
"Toward"
PYTHIA 6.206
CTEQ5L PARP(67)=4
0.00001
0.00001
0
30
60
90
120
150
180
0
30
60
 (degrees)
PY62 (67=1) Total
Flavor Creation
Flavor Excitation
Shower/Fragmentation
PY62 (67=4) Total
“Gluon Splitting”

120
150
180
Flavor Creation
Flavor Excitation
Shower/Fragmentation
b-quark
direction
Predictions of PYTHIA 6.206 (CTEQ5L) with PARP(67)=1
(new default) and PARP(67)=4 (old default) for the azimuthal
angle, , between a b-quark with PT1 > 15 GeV/c, |y1| < 1 and
bbar-quark with PT2 > 10 GeV/c, |y2|<1 in proton-antiproton
collisions at 1.8 TeV. The curves correspond to ds/d (mb/o)
for flavor creation, flavor excitation, gluon splitting, and the
resulting total.
IMFP2006 - Day 2
April 4, 2006
90
 (degrees)
Rick Field – Florida/CDF/CMS

“Toward”
“Away”
bbar-quark
Page 17
Azimuthal Correlations
Old PYTHIA default
(more initial-state radiation)
b-quark Correlations: Azimuthal  Distribution
b-quark Correlations: Azimuthal  Distribution
0.01000
0.010000
1.8 TeV
PT1 > 15 GeV/c
PT2 > 10 GeV/c
|y1| < 1 |y2| < 1
HERWIG 6.4
CTEQ5L
0.001000
0.00100
ds/d (mb/deg)
ds/d (mb/deg)
1.8 TeV
PT1 > 15 GeV/c
PT2 > 10 GeV/c
|y1| < 1 |y2| < 1
0.00010
"Flavor Creation"
CTEQ5L
HERWIG 6.4
0.000100
PYTHIA 6.206
PARP(67)=4
PYTHIA 6.206
PARP(67)=1
0.000010
"Away"
"Toward"
0.00001
30
60
90
120
150
180
 (degrees)
HW64 Total

"Away"
"Toward"
0
Flavor Creation
Flavor Excitation
0.000001
0
30
60
Predictions of HERWIG 6.4 (CTEQ5L) for the
azimuthal angle, , between a b-quark with
PT1 > 15 GeV/c, |y1| < 1 and bbar-quark with
PT2 > 10 GeV/c, |y2|<1 in proton-antiproton
collisions at 1.8 TeV. The curves correspond to
ds/d (mb/o) for flavor creation, flavor
excitation, shower/fragmentation, and the
resulting total.
90
120
150
180
 (degrees)
Shower/Fragmentation
b-quark
direction
New PYTHIA default
(less initial-state radiation)

“Toward”
“Away”
“Flavor Creation”
bbar-quark
IMFP2006 - Day 2
April 4, 2006
Rick Field – Florida/CDF/CMS
Page 18
CDF Run I Analysis
Azimuthal Correlations
b-quark Correlations: Azimuthal  Distribution
0.01000
CDF Preliminary Data
0.0100
1.8 TeV
PT1 > 15 GeV/c
PT2 > 10 GeV/c
|y1| < 1 |y2| < 1
0.01000
1.8 TeV
PT1 > 15 GeV/c
PT2 > 10 GeV/c
|y1| < 1 |y2| < 1
1.8 TeV
PYTHIA 6.206
CTEQ5L PARP(67)=4
ds/d (mb/deg)
d1/s
(mb/deg)
s/dds/d
(mb/deg)
b-quark Correlations: Azimuthal  Distribution
b-quark Correlations: Azimuthal  Distribution
0.1000
0.00100
PYTHIA 6.206
CTEQ5L PARP(67)=4
0.00100
0.00010
0.0010
0.00010
"Away"
"Toward"
"Away"
"Away"
"Toward"
"Toward"
0.00001
0
0.0001
0.00001
0
30
30
60
60
90
90
120
120
150
150

(degrees)
(degrees)
PY62 (67=4) Total
Flavor Creation
Flavor Excitation
30
60
90
150
180
PY62 (67=4) Total
Flavor Creation
Flavor Excitation
Shower/Fragmentation
Shower/Fragmentation
b-quark
direction
Kevin Lannon DPF2002
Now published!

 Run I CDF data for the azimuthal angle, , between a
b-quark |y1| < 1 and bbar-quark |y2|<1 in protonantiproton collisions at 1.8 TeV favored PYTHIA Tune A
(PARP(67) = 4).
IMFP2006 - Day 2
April 4, 2006
120
 (degrees)
180
180
Rick Field – Florida/CDF/CMS
“Toward”
“Away”
bbar-quark
Page 19
The Run 2 J/Y Cross Section
 The J/y inclusive cross-section
includes contribution from the
direct production of J/y and from
-1
4.8
pb
decays from excited charmonium,
Y(2S) , and from the decays of
b-hadrons, B→ J/y + X.
J/y coming from b-hadrons
will be displaced from
primary vertex!
m
J/y
m
Down to
PT = 0!
39.7 pb-1
B
K
CDF (mb)
s(J/Y,|Y(J/Y)| < 0.6)
IMFP2006 - Day 2
April 4, 2006
4.080.02(stat)+0.36(sys)-0.48(sys)
Rick Field – Florida/CDF/CMS
Primary vertex
(i.e. interaction point)
Page 20
CDF Run 2 B-hadron Cross Section
PRD 71, 032001 (2005)
 Run 2 B-hadron PT
distribution compared
with FONLL (CTEQ6M).
Cacciari, Frixone,
Mangano, Nason, Ridolfi
 Good agreement between
theory and experiment!
39.7 pb-1
|Y| < 1.0
B-hadron pT
s(B-hadron)
IMFP2006 - Day 2
April 4, 2006
CDF (mb)
FONLL (mb)
29.40.6(stat)6.2(sys)
27.5+11-8.2
Rick Field – Florida/CDF/CMS
Page 21
CDF Run 2 b-Jet Cross Section
Collision point
 b-quark tag based on displaced vertices. Secondary vertex mass
discriminates flavor.
 Require one secondary vertex tagged b-jet within 0.1 < |y|< 0.7 and
plot the inclusive jet PT distribution (MidPoint, R = 0.7).
IMFP2006 - Day 2
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Rick Field – Florida/CDF/CMS
Page 22
CDF Run 2 b-Jet Cross Section
 Shows the CDF inclusive b-jet cross section (MidPoint, R = 0.7, fmerge =
0.75) at 1.96 TeV with L = 300 pb-1.
 Shows data/theory for NLO (with large scale uncertainties).
 Shows data/theory for PYTHIA Tune A.
IMFP2006 - Day 2
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Rick Field – Florida/CDF/CMS
Page 23
The b-bbar DiJet Cross-Section
 ET(b-jet#1) > 30 GeV, ET(b-jet#2) > 20
GeV, |h(b-jets)| < 1.2.
Preliminary CDF Results:
Systematic
Uncertainty
sbb = 34.5  1.8  10.5 nb
QCD Monte-Carlo Predictions:
PYTHIA Tune A
CTEQ5L
38.71 ± 0.62 nb
HERWIG CTEQ5L
21.53 ± 0.66 nb
MC@NLO
28.49 ± 0.58 nb
“Flavor Creation”
Proton
b-quark
AntiProton
Underlying Event
Differential Cross Section as a function of
the b-bbar DiJet invariant mass!
Underlying Event
Predominately
Flavor creation!
Initial-State
Radiation
 Large Systematic Uncertainty:
 Jet Energy Scale (~20%).
 b-tagging Efficiency (~8%)
b-quark
IMFP2006 - Day 2
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Rick Field – Florida/CDF/CMS
Page 24
The b-bbar DiJet Cross-Section
 ET(b-jet#1) > 30 GeV, ET(b-jet#2) > 20
GeV, |h(b-jets)| < 1.2.
Preliminary CDF Results:
sbb = 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!
JIMMY
Runs with HERWIG and adds
multiple parton interactions!
“Flavor Creation”
b-quark
Initial-State Radiation
JIMMY: MPI
J. M. Butterworth
J. R. Forshaw
M. H. Seymour
IMFP2006 - Day 2
April 4, 2006
Adding multiple parton interactions (i.e.
JIMMY) to enhance the “underlying
event” increases the b-bbar jet cross
section!
Rick Field – Florida/CDF/CMS
Proton
AntiProton
Underlying Event
Underlying Event
b-quark
Final-State
Radiation
Page 25
b-bbar DiJet Correlations
Tune A!
b-jet direction

“Toward”
“Away”
bbar-jet
Differential Cross Section as a
function of  of the two b-jets!
 The two b-jets are predominately “back-toback” (i.e. “flavor creation”)!
“Flavor Creation”
 Pythia Tune A agrees fairly well with the 
correlation!
Proton
b-quark
AntiProton
Underlying Event
Underlying Event
Initial-State
Radiation
Not an
accident!
IMFP2006 - Day 2
April 4, 2006
Rick Field – Florida/CDF/CMS
b-quark
Page 26
Top Production at the Tevatron
 Top quark discovered in 1995
by CDF and DØ.
 Not a surprise: SM quark
sector now complete.
 Now study the detailed
properties of the top:
• Charge.
• Lifetime.
• Branching ratios.
• W-boson helicity.
 Make precision
measurements:
• Cross-sections now 12%!
• Mass now 2%!
 Measure single top production!
IMFP2006 - Day 2
April 4, 2006
Rick Field – Florida/CDF/CMS
Page 27
Top Decay Channels




mt>mW+mb so dominant decay tWb.
The top decays before it hadronizes.
B(W  qq) ~ 67%.
B(W  ln) ~ 11% l = e, m,t.
dilepton
lepton + jets
all hadronic
IMFP2006 - Day 2
April 4, 2006
Rick Field – Florida/CDF/CMS
BR
~5%
~30%
~65%
background
low
moderate
high
Page 28
Dilepton Channel (CDF)
Selection:
•
•
•
•
•
Backgrounds:
2 leptons ET > 20 GeV with opposite sign.
• Physics: Drell-Yan, WW/WZ/ZZ, Z
>=2 jets ET > 15 GeV.
 tt
Missing ET > 25 GeV (and away from any jet). • Instrumental: fake lepton
HT=pTlep+ETjet+MET > 200 GeV.
Z rejection.
65 events
20 events
background
s(tt) = 8.3 ± 1.5 (stat) ± 1.0 (syst) + 0.5 (lumi) pb
IMFP2006 - Day 2
April 4, 2006
Rick Field – Florida/CDF/CMS
Page 29
Lepton+Jets Channel (CDF)
Kinematics
 Selection:
• 1 lepton with pT > 20 GeV/c.
• >= 3 jets with pT > 15GeV/c.
• Missing ET > 20 GeV.
 Backgrounds:
• W+jets
• QCD
central
 Use 7 kinematic variables in neural net to
discriminate signal from background!
One of the 7
variables!
spherical
binned likelihood fit
Neural net
output!
s(tt) = 6.0 ± 0.6 (stat) ± 0.9 (syst) pb
IMFP2006 - Day 2
April 4, 2006
Rick Field – Florida/CDF/CMS
Page 30
Lepton+Jets Channel (CDF)
 Require b-jet to be tagged for
discrimination.
b-Tagging
1 b tag
Tagging efficiency for b jets~50%
for c jets~10%
for light q jets < 0.1%
2 b tags
HT>200GeV
~150 events ~45 events
Small
background!
s(tt) = 8.2 ± 0.6 (stat) ± 1.1 (syst) pb
IMFP2006 - Day 2
April 4, 2006
2.0
s (tt )  8.81.2
(stat)
1.1
1.3 (syst)pb
Rick Field – Florida/CDF/CMS
Page 31
All Hadronic Channel (DØ)
 Huge QCD background!
 Selection:
• >=6 jets with pT > 15 GeV/c.
• >=1 b tagged.
• NN discriminant > 0.9.
 Use 6 kinematic variables in
neural net to discriminate signal
from background!
Geometric mean of 5th and 6th leading jet ET
One of the 6
variables!
1.5
s (tt )  5.22.6
2.5 (stat)1.0 (syst)  0.3(lumi)pb
IMFP2006 - Day 2
April 4, 2006
Rick Field – Florida/CDF/CMS
Page 32
Tevatron Top-Pair Cross Section
CDF Run 2 Preliminary
Theory
0.7
s (tt )  6.70.9
pb
Bonciani et al., Nucl. Phys. B529, 424 (1998)
Kidonakis and Vogt, Phys. Rev. D68, 114014 (2003)
IMFP2006 - Day 2
April 4, 2006
Rick Field – Florida/CDF/CMS
Page 33
New CDF Mtop Results
Transverse
decay length!
Mtop (template) = 173.4 ± 2.5 (stat. + jet E) ± 1.3 (syst.) GeV
Mtop (matrix element) = 174.1 ± 2.5 (stat. + jet E) ± 1.4 (syst.) GeV
Mtop (Lxy) = 183.9 +15.7-13.9 (stat.) ± 5.6 (syst.) GeV
CDF Dilepton: Mtop (matrix element) = 164.5 ± 4.5 (stat.) ± 3.1 (jet E. + syst.) GeV
CDF Lepton+jets:
IMFP2006 - Day 2
April 4, 2006
Rick Field – Florida/CDF/CMS
Page 34
Top Quark Mass
Summer 2005
New since Summer 2005
Dilepton:
CDF-II MtopME = 164.5 ± 5.5 GeV
Lepton+Jets:
CDF-II MtopTemp = 174.1 ± 2.8 GeV
CDF-II MtopME = 173.4 ± 2.9 GeV
CDF Combined:
MtopCDF = 172.0 ± 1.6 ± 2.2 GeV
= 172.0 ± 2.7 GeV
IMFP2006 - Day 2
April 4, 2006
Rick Field – Florida/CDF/CMS
Page 35
Top Cross-Section vs Mass
Tevatron Summer 2005
CDF Winter 2006
CDF combined
Updated CDF+DØ combined result is coming soon!
IMFP2006 - Day 2
April 4, 2006
Rick Field – Florida/CDF/CMS
Page 36
Is Anything “Goofy”?
 Possible discrepancy between
l + jets and the dilepton
channel measurements of the
top mass??
 Is it statistical?
• ME(dilepton) vs
Templ(l+jets):
c2 = 2.9/1, Prob = 0.09
(accounts for correlated
systematics).
 Is there a missing systematic?
 This is probably nothing, but
we should keep an eye on it!
IMFP2006 - Day 2
April 4, 2006
Rick Field – Florida/CDF/CMS
Page 37
Future Top Mass Measurements
Systematic
Source
Uncertainty
(GeV/c2)
ISR/FSR
0.7
Model
0.7
b-jet
0.6
Method
0.6
PDF
0.3
Total
1.3
Jet Energy
2.5
CDF
 Expect significant reduction in jet energy scale uncertainty with more data.
 Today we have CDF-II Mtop(Temp) = 174.1 ± 2.8 GeV (~0.7 fb-1).
 CDF should be able to achieve 1.5 GeV uncertainty on top mass!
IMFP2006 - Day 2
April 4, 2006
Rick Field – Florida/CDF/CMS
Page 38
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!
Tevatron Run I + LEP2
Summer 05
This spring?
114 GeV Higgs very interesting for
the Tevatron!
IMFP2006 - Day 2
April 4, 2006
Rick Field – Florida/CDF/CMS
Page 39
Top: Charge, Branching, Lifetime, W Helicity
Top Charge
DØ Prelim.
365 pb-1
Top Lifetime
CDF Prelim.
318 pb-1
Exclude |Q| = 4/3 at 94% CL
ttop< 1.75x10-13s
cttop< 52.5mm
at 95%CL
Everything consistent with the
Standard Model! Impact Parameter (mm)
Reconstructed Top Charge (e)
370 pb-1
f+ (DØ combined) = 0.04
± 0.11(stat) ± 0.06(syst)
f+ (SM pred.) = 0
SM
signal
hep-ex/0603002
IMFP2006 - Day 2
April 4, 2006
signal+bgrnd
bgrnd
Rick Field – Florida/CDF/CMS
Page 42
Other Sources of Top Quarks
Strongly Produced tt Pairs
 Dominant production mode
sNLO+NLL = 6.7  1.2 pb
 Relatively clean signature
 Discovery in 1995
g
~15%
g
ElectroWeak Production: Single Top
 Larger background
 Smaller cross section s ≈ 2 pb
 Not yet observed!
IMFP2006 - Day 2
April 4, 2006


Rick Field – Florida/CDF/CMS
q
~85%
t
t
q


Page 43
Single Top Production
s-channel
qq  W *  tb
tW associated production
t-channel
bg  tW 
qb  q ' t
(mtop=175 GeV/c2)
s-channel
t-channel
Associated tW
Tevatron sNLO
0.88  0.11 pb
1.98  0.25 pb
~ 0.1 pb
LHC sNLO
10.6  1.1 pb
247  25 pb
62+17 -4 pb
CDF
< 18 pb
< 13 pb
D0
< 17 pb
< 22 pb
Run I
95% C.L.
< 14 pb
B.W. Harris et al.:Phys.Rev.D66,054024
Z.Sullivan Phys.Rev.D70:114012
IMFP2006 - Day 2
April 4, 2006
Rick Field – Florida/CDF/CMS
Combine
(s+t)
T.Tait: hep-ph/9909352
Belyaev,Boos: hep-ph/0003260
Page 44
New Single Top Results from CDF
 To the network 2D output, CDF applies a
maximum likelihood fit and the best fits
for t and s-channels are:
1.9
0.1
σ t ch  0.6 0.6
(stat) 0.1
(syst)pb
2.2
0.5
σ s ch  0.3 0.3
(stat) -0.3
(syst) pb
The new CDF
limits!
t-channel:
s < 3.1 pb @ 95% C.L.
s-channel:
s < 3.2 pb @ 95% C.L.
IMFP2006 - Day 2
April 4, 2006
Rick Field – Florida/CDF/CMS
Page 45
Single Top at the Tevatron
95% C.L. limits on single top cross-section
Channel
CDF (696 pb-1)
DØ (370 pb-1)
Combined
3.4 pb (2.9 pb)
s-channel
3.2 pb (0.9 pb)
5.0 pb
t-channel
3.1 pb (2 pb)
4.4 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 !!!!
IMFP2006 - Day 2
April 4, 2006
Rick Field – Florida/CDF/CMS
Page 46
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!
IMFP2006 - Day 2
April 4, 2006
Rick Field – Florida/CDF/CMS
Page 47