What a Difference the Last 2 Years
Have Made!
Physics at the Tevatron
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
CDF Run 2
IFT - University of Florida
February 29, 2008
Happy Leap
Year Day!
Rick Field – Florida/CDF/CMS
Page 1
Tevatron Performance
The data collected since IMFP 2006 more than doubled
the total data collected in Run 2!
IMFP 2006
~1.5 fb-1 delivered
~1.2 fb-1 recorded
IMFP 2008
~3.3 fb-1 delivered
~2.8 fb-1 recorded
~1.6 fb-1
Integrated Luminosity per Year
23 tt-pairs/month!
 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
IFT - University of Florida
February 29, 2008
 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
Rick Field – Florida/CDF/CMS
Page 2
Many New Tevatron Results!
Some of the CDF Results since IMFP2006













Observation of Bs-mixing: Δms = 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).
cannot
cover
the(±2.2) GeV.
PrecisionI Top
mass possibility
measurement:
Mtop =all
170.5
great physics
results
from
W-width measurement:
2.032
(±0.071)
GeV.the
Tevatron
since
IMFP
WZ discovery
(6-sigma):
s = 5.0
(±1.7)2006!
pb.
I will
show a few of the results!
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.
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 3
In Search of Rare Processes
PRODUCTION CROSS SECTION (fb)
We might get lucky!
IFT - University of Florida
February 29, 2008
We are beginning to measure
cross-sections ≤ 1 pb!
s(pT(jet) > 525 GeV) ≈ 15 fb!
~9 orders of
magnitude
W’, Z’, T’
Higgs ED
Rick Field – Florida/CDF/CMS
1 pb
15 fb
Page 4
Jets at Tevatron
“Theory Jets”
“Tevatron Jets”
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”!
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 5
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?
PT(hard)
 This also cannot really be done, but again if you trust the MonteInitial-State Radiation
AntiProton Carlo models you can try and do it by using the Monte-Carlo
models.
Underlying Event
Outgoing Parton
Proton
Underlying Event
Outgoing Parton
Final-State
Radiation
IFT - University of Florida
February 29, 2008
The “underlying event” consists of
hard initial & final-state radiation
plus the “beam-beam remnants” and
possible multiple parton interactions.
Rick Field – Florida/CDF/CMS
Page 6
Inclusive Jet Cross Section (CDF)
 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).
IMFP2006
CTEQ4M PDFs
CTEQ4HJ PDFs
CTEQ4HJ
CTEQ4M
Run I CDF Inclusive Jet Data
(Statistical Errors Only)
JetClu RCONE=0.7
0.1<||<0.7
R=F=ET /2 RSEP=1.3
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 7
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 today 1.13 fb-1
 0.1 < |yjet| < 0.7
 Compared with NLO QCD
IMFP2006
s(pT > 525 GeV) ≈ 15 fb!
Sensitive to UE + hadronization
effects for PT < 200 GeV/c!
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 8
KT Algorithm
 kT Algorithm:
Begin







For each precluster, calculate
di  pT2,i
For each pair of preculsters, calculate
( y  y j ) 2  (i   j ) 2
dij  min( pT2 ,i , pT2 , j ) i
D2
Find the minimum of all di and dij.
Merge
i and j
yes
Minumum
is dij?
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!
no
Move i to list of jets
yes
Will the KT algorithm be
effective in the collider
environment where there is
an “underlying event”?
Any
Preclusters
left?
Raw Jet ET = 533 GeV
KT Algorithm
Raw Jet ET = 618 GeV
no
End
Outgoing Parton
PT(hard)
Initial-State Radiation
Proton
AntiProton
Underlying Event
Underlying Event
CDF Run 2
Outgoing Parton
Final-State
Radiation
IFT - University of Florida
February 29, 2008
Only towers with ET > 0.5 GeV are shown
Rick Field – Florida/CDF/CMS
Page 9
KT Inclusive Jet Cross Section (CDF)





KT Algorithm (D = 0.7)
Data corrected to the hadron level
L = 385 pb-1 today 1.0 fb-1
0.1 < |yjet| < 0.7
Compared with NLO QCD.
IMFP2006
Sensitive to UE + hadronization
effects for PT < 200 GeV/c!
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 10
High x Gluon PDF
from Run I
 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
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
low x
Page 11
KT Forward Jet Cross Section (CDF)
 KT Algorithm (D = 0.7).
 Data corrected to the hadron
level.
-1
 L = 385 pb-1. today 1.0 fb
 Five rapidity regions:
 |yjet| < 0.1




IMFP2006
0.1 < |yjet| < 0.7
0.7 < |yjet| < 1.1
1.1 < |yjet| < 1.6
1.6 < |yjet| < 2.1
 Compared with NLO QCD
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 12
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| < 0.1
 0.1 < |yjet| < 0.7
 0.7 < |yjet| < 1.1
 1.1 < |yjet| < 1.6
 1.6 < |yjet| < 2.1
 Compared with NLO QCD
since IMFP2006
1.0 fb-1
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 13
DiJet Cross Section (CDF)
since IMFP2006
 MidPoint Cone Algorithm
(R
= 0.7, fmerge = 0.75)
 Data corrected to the hadron level
 L = 1.13 fb-1
 |yjet1,2| < 1.0
 Compared with NLO QCD
CDF Run II Preliminary
Sensitive to UE + hadronization effects!
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 14
Inclusive Jet versus DiJet (CDF)
Inclusive Jet (CDF)
DiJet (CDF)
 MidPoint Cone Algorithm
(R = 0.7, fmerge = 0.75)
 CTEQ6.1M  = PT/2
IFT - University of Florida
February 29, 2008
 MidPoint Cone Algorithm
(R = 0.7, fmerge = 0.75)
 CTEQ6.1M  = mean(PT1,PT2)
Rick Field – Florida/CDF/CMS
Page 15
CDF DiJet Event: M(jj) ≈ 1.4 TeV
ETjet1 = 666 GeV ETjet2 = 633 GeV
Esum = 1,299 GeV M(jj) = 1,364 GeV
Exclusive p+p → p+p+e++e- (16 events)
s = 1.6 ± 0.3 pb
CDF Run II
IFT - University of Florida
February 29, 2008
since IMFP2006
M(jj)/Ecm ≈ 70%!!
Rick Field – Florida/CDF/CMS
Page 16
“Towards”, “Away”, “Transverse”
Look at the charged
particle density, the
charged PTsum density
and the ETsum density in
all 3 regions!
 Correlations relative to the leading jet
Jet #1 Direction
“Transverse” region is
very sensitive to the
“underlying event”!
Charged particles pT > 0.5 GeV/c || < 1
Calorimeter towers ET > 0.1 GeV || < 1
2
“Toward-Side” Jet

Away Region
Jet #1 Direction

Transverse
Region
“Toward”
“Toward”
“Transverse”
“Transverse”
“Away”
“Transverse”
“Transverse”

Leading
Jet
Toward Region
“Away”
Transverse
Region
“Away-Side” Jet
Away Region
0
-1

+1
 Look at correlations in the azimuthal angle relative to the leading charged particle jet (|| <

1) or the leading calorimeter jet (|| < 2).
o
o
o
o
Define || < 60 as “Toward”, 60 < || < 120 as “Transverse ”, and || > 120 as “Away”.
o
Each of the three regions have area  = 2×120 = 4/3.
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 17
Overall Totals (|| < 1)
ETsum = 775 GeV!
“Leading Jet”
Overall Totals versus PT(jet#1)
ETsum = 330 GeV
1000
CDF Run 2 Preliminary
ETsum (GeV)
data corrected
pyA generator level
Jet #1 Direction

PTsum (GeV/c)
Average
100
“Overall”
Nchg
"Leading Jet"
MidPoint R=0.7 |(jet#1)|<2
10
PTsum = 190 GeV/c
Charged Particles (||<1.0, PT>0.5 GeV/c)
Stable Particles (||<1.0, all PT)
1
0
50
Nchg = 30
100
150
200
250
300
350
400
PT(jet#1) (GeV/c)
 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)..
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 18
“Towards”, “Away”, “Transverse”
“Leading Jet”
Jet #1 Direction

“Toward”
“Transverse”
“Transverse”
“Away”
ETsum
Density
(GeV)
Charged
PTsum
Density
(GeV/c)
Average
Charged
Density
Charged
Particle
Density:
dN/dd
Charged
PTsum
Density:
dPT/dd
ETsum
Density:
dET/dd
5
100.0
100.0
CDFCDF
RunRun
2 Preliminary
2 Preliminary
4
data corrected
data"Toward"
corrected
pyA generator level
pyA generator level
10.0
3
"Toward"
"Away"
"Away"
Factor of ~13
"Toward"
"Transverse"
Factor of ~16
"Away"
"Transverse" "Leading Jet"
Factor of MidPoint
~4.5 R=0.7 |(jet#1)|<2
2
1.0
1.0
1
0 0.1
0.1
0 0
0
"Transverse"
CDF Run 2 Preliminary
data corrected
pyA generator level
50 50
50
100100
100
150
150
150
"Leading Jet"
"Leading Jet"
MidPoint R=0.7 |(jet#1)|<2
MidPoint R=0.7 |(jet#1)|<2
ChargedStable
Particles
(||<1.0,
PT>0.5
GeV/c)
Charged
Particles
(||<1.0,
PT>0.5
GeV/c)
Particles
(||<1.0,
all
PT)
200
200
200
250
250
250
300
300
300
350
350
350
400
400
400
PT(jet#1)
PT(jet#1)(GeV/c)
(GeV/c)
PT(jet#1)
(GeV/c)
Data at
at 1.96
1.96 TeV
TeV on
on the
the charged
density ofparticle
charged particles,
dN/dd,
p > 0.5 GeV/c
and || < 1 for
 Data
Data
pT sum
density, with
dPT/dd,
and ||
T > 0.5 GeV/c

at 1.96
TeV on
the particle
scalar ETscalar
sum density,
dET/dd,
forT|| < with
1 for p“leading
jet” events
as<a
jet” eventsevents
as a function
of theofleading
jet pTjet
forpthe
“toward”,
“away”,
and “transverse”
1“leading
for “leading
function
the leading
the “toward”,
“away”,
“transverse”
T for
function
of thejet”
leading jetas
pTafor
the “toward”,
“away”,
and
“transverse”
regions.
Theand
data
are corrected
regions.
The
data
are
corrected
to
the
particle
level
(with
errors
that
include
both
the
statistical
error and
and
regions.
The
data
are
corrected
to
the
particle
level
(with
errors
that
include
both
the
statistical
error
to the particle level (with errors that include both the statistical error and the systematic uncertainty)
and
the systematic
systematic uncertainty)
uncertainty) and
and are
are compared
compared with
with PYTHIA Tune
Tune A
A at
at the
the particle
particle level
level (i.e.
(i.e. generator
generator
the
are
compared with PYTHIA
Tune A
at the particlePYTHIA
level (i.e. generator
level).
level).
level).
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 19
The Leading Jet Mass
“Leading Jet”
Leading Jet Invariant
Off by ~2Mass
GeV
12.0
70
“Toward”
“Transverse”
“Transverse”
“Away”
Data
Theory
(GeV)
Jet-Mass
(GeV)
Jet #1 Direction

CDF
CDFRun
Run22Preliminary
Preliminary
60
"Leading Jet"
MidPoint R=0.7 |(jet#1)|<2
data
datacorrected
corrected
generator
generatorlevel
leveltheory
theory
8.0
50
HW
PY Tune A
40
4.0
30
PY Tune A
20
0.0
10
-4.0
0
00
"Leading Jet"
MidPoint R=0.7 |(jet#1)|<2
HW
5050
100
100
150
150
200
200
250
250
300
300
350
400
PT(jet#1
uncorrected)
PT(jet#1)
(GeV/c)(GeV/c)
 Data
Shows
Theory
for thejet
leading
jet invariant
for “leading
jet”
as a function
of thejet

atthe
1.96Data
TeV- on
the leading
invariant
mass for mass
“leading
jet” events
asevents
a function
of the leading
jet p for PYTHIA Tune A and HERWIG (without MPI).
pleading
T. The dataTare 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).
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 20
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 |y|< 1.2 and study
the two b-jets (Mjj, jj, etc.).
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 21
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)
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 22
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
IFT - University of Florida
February 29, 2008
Q
g
g
Q
g
Q
+
g
Q
Amp (FE)
Rick Field – Florida/CDF/CMS
g
Amp (GS)
g
Page 23
2
bb DiJet Cross Section (CDF)
 ET(b-jet#1) > 35 GeV, ET(b-jet#2) > 32
GeV, |(b-jets)| < 1.2.
IMFP2006
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
Adding multiple parton interactions (i.e.
JIMMY) to enhance the “underlying
event” increases the b-bbar jet cross
section!
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Proton
AntiProton
Underlying Event
Underlying Event
b-quark
Final-State
Radiation
Page 24
bb DiJet Cross Section (CDF)
since IMFP2006
 ET(b-jet#1) > 35 GeV,
ET(b-jet#2) > 32 GeV, |(b-jets)| < 1.2.
Systematic
Uncertainty
Preliminary CDF Results:
sbb = 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
Predominately
Flavor creation!
“Flavor Creation”
Proton
b-quark
AntiProton
Underlying Event
Underlying Event
Sensitive to the “underlying event”!
Initial-State
Radiation
b-quark
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 25
bb DiJet  Distribution (CDF)
since IMFP2006
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”.
 It takes NLO + “underlying event” to get it
right!
“Flavor Creation”
“Gluon Splitting”
Proton
AntiProton
Underlying Event
Underlying Event
Proton
b-quark
AntiProton
Underlying Event
Underlying Event
Initial-State
Radiation
Initial-State
Radiation
b-quark
Q-quark
Q-quark
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 26
Z + b-Jet Production (CDF)
since IMFP2006
 Important background for new physics!





IMFP2006
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.
today
1.5 fb-1
Extract fraction of b-tagged jets from
secondary vertex mass distribution: NO
assumption on the charm content.
s ( ZObservable
 bjet )  0.96  0.32 CDF
0.14Data
pb
PYTHIA Tune A
s [ Z  bjet]
0.94±0.15±0.15
pb)  0.0033( syst
-- )
R  s(Z+b-jet)  0.0237
 0.0078( stat
s [ Z  jet]
MCFM NLO (+UE)
0.51 (0.56) pb
s(Z+b-jet)/s(Z)
0.369±0.057±0.055 %
0.35%
0.21 (0.23) %
s(Z+b-jet)/s(Z+jet)
2.35±0.36±0.45 %
2.18%
1.88 (1.77) %
Sensitive to the “underlying event”!
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 27
Z-boson Cross Section (CDF)
IMFP2006
QCD
Drell-Yan
 Impressive agreement between experiment
and NNLO theory (Stirling, van Neerven)!
s(Z→e+e-)
IFT - University of Florida
February 29, 2008
CDF (pb)
NNLO (pb)
254.93.3(stat)4.6(sys)15.2(lum)
252.35.0
Rick Field – Florida/CDF/CMS
Page 28
Z-boson Cross Section (CDF)
IMFP2006
 Impressive agreement between experiment and NNLO theory
(Stirling, van Neerven)!
s(Z→+-)
IFT - University of Florida
February 29, 2008
CDF (pb)
NNLO (pb)
261.22.7(stat)6.9(sys)15.1(lum)
252.35.0
Rick Field – Florida/CDF/CMS
Page 29
Z-Boson Rapidity Distribution
 Measure ds/dy for



since IMFP2006
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!
1.1fb-1 91,362 events 66 < MZ < 116 GeV
CDF
Events
Zcc
IFT - University of Florida
February 29, 2008
ZCC
ZCP
ZPP
28,097
46,676
16,589
Zcp
Rick Field – Florida/CDF/CMS
Plug-Plug
electrons!
Zpp
Page 30
Z-Boson Rapidity Distribution
since IMFP2006
 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+ +NNL0
CTEQ6.1
PDF
NLL0
MRST
PDF
s(Z→e+e-)
IFT - University of Florida
February 29, 2008
CDF (pb)
263.3±0.9(stat)±3.8(sys)
Rick Field – Florida/CDF/CMS
NLO + MRST PDF
NNLO (pb)
252.35.0
Page 31
The Z→tt Cross Section (CDF)
 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.
Signal
cone
 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.
Isolation
cone
 Channel for Z→ττ: electron + isolated track
• One t decays to an electron: τ→e+X (ET(e) > 10 GeV) .
• One t decays to hadrons: τ → h+X (pT > 15GeV/c).
 Remove Drell-Yan e+e- and apply event topology cuts for non-Z
background.
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 32
The Z→tt 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 sign
same sign,
opposite sign
s(Z→t+t-)
IFT - University of Florida
February 29, 2008
IMFP2006
CDF (pb)
NNLO (pb)
264
± 23 (stat) ± 14 (sys) ± 15 (lum)
26520(stat)21(sys)15(lum)
252.35.0
Rick Field – Florida/CDF/CMS
Page 33
Higgs → tt Search (CDF)
140 GeV
Higgs Signal!
IMFP2006
 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.
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 34
Higgs → tt Search (CDF)
since IMFP2006
No Significant Excess of events above SM background is observed!
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 35
W-boson Cross Section (CDF)
 Extend electron coverage to the forward
region (1.2 < || < 2.8)!
IMFP2006
48,144 W candidates ~4.5% background
overall efficiency of signal ~7%
s(W)/s(Z)
s(W)
CDF
NNLO
10.920.15(stat)0.14(sys)
10.690.08
L
CDF (pb)
NNLO(pb)
Central
electrons
72 pb-1
277510(stat)53(sys)167(lum)
268754
Forward
electrons
223 pb-1
281513(stat)94(sys)169(lum)
268754
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 36
W-Boson Mass Measurement
since IMFP2006
 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!
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 37
W-Boson Width Measurement
since IMFP2006
 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.
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 38
 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!
u
p d
u
e+
W+
d
u
u
xG(x,Q2)
W Production Charge Asymmetry
Q2 = 100 GeV2
MRST2004NLO
u
d
p
10-3
e
W-
10-2
10-1
1
W+
ds  / dyW  ds  / dyW
A( yW ) 
ds  / dyW  ds  / dyW
antiproton proton
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
y
Page 39
x
W 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!
since IMFP2006
 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 crosssection, s(yW).
The process is iterated since s(yW) depends on the
asymmetry.
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 40
W + g Cross Sections (CDF)
IMFP2006
ET(g) > 7 GeV
R(lg) > 0.7
s(W+g)*BR(W->l)
IFT - University of Florida
February 29, 2008
CDF (pb)
NLO (pb)
19.71.7(stat)2.0(sys)1.1(lum)
19.31.4
Rick Field – Florida/CDF/CMS
Page 41
W + g Cross Sections (CDF)
since IMFP2006
ET(g) > 7 GeV
R(lg) > 0.7
s(W+g)*BR(W->l)
IFT - University of Florida
February 29, 2008
CDF (pb)
NLO (pb)
18.03±0.65(stat)±2.55(sys)
±1.05(lum)
19.71.7(stat)2.0(sys)1.1(lum)
19.31.4
Rick Field – Florida/CDF/CMS
Page 42
Z + g Cross Sections (CDF)
IMFP2006
Note: s(Wg)/s(Zg) ≈ 4
while s(W)/s(Z) ≈ 11
ET(g) > 7 GeV
R(lg) > 0.7
s(Z+g)*BR(Z->ll)
IFT - University of Florida
February 29, 2008
CDF (pb)
NLO (pb)
5.30.6(stat)0.3(sys)0.3(lum)
5.40.3
Rick Field – Florida/CDF/CMS
Page 43
Z + g Cross Sections (CDF)
since IMFP2006
390 events
ET(g) > 7 GeV
R(lg) > 0.7
Meeg > 40 GeV/c2
s(Z+g)*BR(Z->ee)
IFT - University of Florida
February 29, 2008
CDF (pb)
NLO (pb)
4.90.3(stat)0.3(sys)0.3(lum)
4.70.4
Rick Field – Florida/CDF/CMS
Page 44
The W+W Cross-Section
IMFP2006
Campbell & Ellis 1999
pb-1
CDF (pb)
NLO (pb)
s(WW) CDF
184
14.6+5.8(stat)-5.1(stat)1.8(sys)0.9(lum)
12.40.8
s(WW) DØ
240
13.8+4.3(stat)-3.8(stat)1.2(sys)0.9(lum)
12.40.8
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 45
The W+W Cross-Section (CDF)
IMFP2006





WW→dileptons + MET
Two leptons pT > 20 GeV/c.
Z veto.
MET > 20 GeV.
Zero jets with ET>15 GeV
and ||<2.5.
We are beginning to study the details
of 95 events with
Observe
37.2 background!
Di-Boson production at the Tevatron!
s(WW)
L
CDF (pb)
NLO (pb)
825 pb-1
13.72.3(stat)1.6(sys)1.2(lum)
12.40.8
Missing ET!
IFT - University of Florida
February 29, 2008
Lepton-Pair Mass!
Rick Field – Florida/CDF/CMS
ET Sum!
Page 46
WW+WZ Cross-Section
since IMFP2006
NLO Theory
σWW × Br(W→l, W→jj) = 12.4 pb × 0.146 = 1.81 pb
σWZ × Br(W→l, Z→jj) = 3.96 pb × 0.07 = 0.28 pb
s(WW+WZ)×BR(lvjj)
IFT - University of Florida
February 29, 2008
CDF (pb)
NLO (pb)
1.47 ± 0.77(stat) ± 0.38(sys)
2.1 ± 0.2 pb
Rick Field – Florida/CDF/CMS
Page 47
The Z+W, Z+Z Cross Sections
IMFP2006
W+Z → trileptons + MET
Observe 2 events with a
background of 0.9±0.2!
Upper Limits
W+Z, Z+Z
Limit (pb)
NLO (pb)
CDF (194 pb-1) sum
< 15.2 (95% CL)
5.00.4
DØ (300 pb-1) W+Z
< 13.3 (95% CL)
3.70.1
CDF (825 pb-1) W+Z
< 6.34 (95% CL)
3.70.1
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 48
The W+Z Cross Section
since IMFP2006
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 σ significance!
s(W+Z)
IFT - University of Florida
February 29, 2008
L
CDF (pb)
NLO (pb)
1.9 fb-1
4.3±1.3(stat) ±0.2(sys) ±0.3(lum)
3.70.3
Rick Field – Florida/CDF/CMS
Page 49
The Z+Z Cross Section
since IMFP2006
Strategy:
 Search for events with either 4 leptons
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.
or
ZZ
ZZdecaying
decayinginto
into2 4
leptons
leptons+ MET
3.0 σ significance!
s(Z+Z)
IFT - University of Florida
February 29, 2008
L
CDF (pb)
NLO (pb)
1.9 fb-1
0.75+0.71-0.54
1.4±0.1
Rick Field – Florida/CDF/CMS
Page 50
Higgs → W+W
 We are within a factor of two of
the standard model
Higgs (160 GeV) → WW!
IFT - University of Florida
February 29, 2008
since IMFP2006
Rick Field – Florida/CDF/CMS
Page 51
Heavy Quark Production at the Tevatron
with 1 fb-1  Total inelastic stot ~ 100 mb which is
103-104 larger than the cross section for
~1.4 x 1014
~1 x 1011
~6 x 106
~6 x 105
~14,000
~5,000
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
 and e.
• For hadronic decays we trigger on one
or more displaced tracks (i.e. large
impact parameter).
CDF-SVT
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 52
B-Baryon Observations (CDF)
since IMFP2006
The Tevatron is excellent at
producing particles containing
and c quarks
(Bu, Bd, Bs, Bc, Sb, Xb,b)
b
Xb
Sb
bc
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 53
Top Decay Channels




mt>mW+mb so dominant decay tWb.
The top decays before it hadronizes.
B(W  qq) ~ 67%.
B(W  l) ~ 11% l = e, ,t.
dilepton
lepton + jets
all hadronic
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
BR
~5%
~30%
~65%
background
low
moderate
high
Page 54
Dilepton Channel (CDF)
Selection:
•
•
•
•
•
2 leptons ET > 20 GeV with opposite sign. Backgrounds:
• 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.
since IMFP2006
IMFP2006
84 events
65 events
20 events
background
s(tt)== 6.16
8.3 ±±1.5
(stat)
±±
1.00.72
(syst)
+ 0.5
(lumi)
pb pb
s(tt)
1.05
(stat)
(syst)
+ 0.37
(lumi)
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 55
Lepton+Jets Channel (CDF)
 Require b-jet to be tagged for
discrimination.
b-Tagging
1 b tag
IMFP2006
~70 events
HT>200GeV
Tagging efficiency for b jets~50%
for c jets~10%
for light q jets < 0.1%
2 b tags
~180 events
~150 events ~45 events
Small
background!
2.0
s(tt)
s(tt)== 8.2
8.8±±0.6
0.5
0.8(stat)
(stat)±±1.1
0.8
1.2(syst)
(sys)
(sys)±±
pb
0.5
0.5(lum)
(lum)
pb
s (tt ) pb
8.81.2
(stat)
1.1
1.3 (syst)pb
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 56
Tevatron Top-Pair Cross Section
since IMFP2006
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)
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 57
Top Quark Mass
since IMFP2006
Leptons+Jets
Dilepton Channel
Channel
Mt=170.4 ± 3.1(stat) ± 3.0(sys)GeV/c2
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 58
Top Cross-Section vs Mass
Tevatron Summer 2005
CDF Winter 2006
CDF combined
Cacciari, Mangano, et al., hep-ph/0303085
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 59
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
114 GeV Higgs very interesting for
the Tevatron!
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 60
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!
IFT - University of Florida
February 29, 2008


Rick Field – Florida/CDF/CMS
q
~85%
t
t
q


Page 62
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
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Combine
(s+t)
T.Tait: hep-ph/9909352
Belyaev,Boos: hep-ph/0003260
Page 63
Single Top at the Tevatron
IMFP2006
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 !!!!
- R. Field (IMFP2006)
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 64
Single Top Production
since IMFP2006
Single Top
Signal!
DØ Combination
3.6s!
3.4s!
Expected sensitivity: 2.1s
ss+t= 4.9 ±1.4 pb
ss= 1.0, st =4.0 pb
PRL 98 18102 (2007)
IFT - University of Florida
February 29, 2008
First direct measurement of Vtb
0.68 <|Vtb|< 1 @ 95%CL or
|Vtb| = 1.3 ± 0.2
Rick Field – Florida/CDF/CMS
Page 65
Single Top Production
since IMFP2006
3.1s!
ss+t= 2.7 ± 1.2 pb
ss= 1.1, st =1.3 pb
Expected sensitivity: 2.9s
Observed significance: 2.7s
IFT - University of Florida
February 29, 2008
ss+t= 3.0 ± 1.2 pb
ss= 1.1, st =1.9 pb
Expected sensitivity: 3.0s
Rick Field – Florida/CDF/CMS
Page 66
Measurement of |Vtb| (CDF)
 Using the Matrix Element cross section
measurement, CDF determines |Vtb|
assuming |Vtb| >> |Vts|, |Vtd|!
CDF Run II Preliminary L=1.5 fb-1
s-channel
t-channel
|Vtb|= 1.02 ± 0.18 (exp) ± 0.07(thy)
DØ |Vtb|>0.68, |Vtb| = 1.3 ±0.2
IFT - University of Florida
February 29, 2008
Z. Sullivan, Phys.Rev. D70 (2004) 114012
Rick Field – Florida/CDF/CMS
Page 67
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! Central Electron Candidate
Charge:
u -1, Eta=-0.72d MET=41.6 GeV
t-channel
single top!
EPD > 0.9
Jet1: Et=46.7 GeV Eta=-0.6 b-tag=1
Jet2: Et=16.6 GeV Eta=-2.9 b-tag=0
Q× = 2.9 (t-channel signature)
EPD=0.95
CDF Run: 211883, Event: 1911511
Jet1
Lepton
Jet2
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 68
Single Top at the Tevatron
since IMFP2006
Single top cross-section measurements!
Channel
Theory
CDF (1.5 fb-1)
DØ (0.9 fb-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
 Single top has (almost) been seen at the Tevatron at the
expected rate!
If you think 3.5s is enough to claim discovery?
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 69
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!
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 70
Top-AntiTop Resonances
 The excess has disappeared!
since IMFP2006
Excess is
gone!
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 71
Tevatron Measurements
Jets
b-quarks
We are getting very close to
the Higgs and/or new physics!
W
Z
W+g
Single top
Z+g
W+W
tt
W+Z
Z+Z
IFT - University of Florida
February 29, 2008
Rick Field – Florida/CDF/CMS
Page 72