Studying the
“Underlying Event” at CDF
Sorry to be so slow!!
Rick Field
Craig Group
Deepak Kar
To be submitted to PRD
CDF Run 2
“Leading Jet”
The goal is to produce data (corrected to the
particle level) that can be used by the theorists to
tune and improve the QCD Monte-Carlo models
that are used to simulate hadron-hadron
collisions.
Drell-Yan Production
Outgoing Parton
Lepton
PT(hard)
Initial-State Radiation
Proton
AntiProton
Underlying Event
Outgoing Parton
CDF Paper Seminar
Fermilab - March 11, 2010
Underlying Event
Proton
AntiProton
Underlying Event
Final-State
Radiation
Underlying Event
Anti-Lepton
Rick Field – Florida/CDF/CMS
Page 1
All use LO as
with L = 192 MeV!
UE Parameters
ISR Parameter
PYTHIA 6.2 Tunes
Parameter
Tune AW
Tune DW
Tune D6
PDF
CTEQ5L
CTEQ5L
CTEQ6L
MSTP(81)
1
1
1
MSTP(82)
4
4
4
PARP(82)
2.0 GeV
1.9 GeV
1.8 GeV
PARP(83)
0.5
0.5
0.5
PARP(84)
0.4
0.4
0.4
Uses CTEQ6L
Tune A energy dependence!
PARP(85) of the
0.9 CDF 1.0
1.0
None
Tunes included
PARP(86)
0.95
1.0
1.0
any
“min-bias”
data
in
the
PARP(89)
1.8 TeV
1.8 TeV
1.8 TeV
PARP(90)
0.25
0.25
0.25
determination
of the
parameters!
PARP(62)
1.25
1.25
1.25
PARP(64)
0.2
0.2
0.2
PARP(67)
4.0
2.5
2.5
MSTP(91)
1
1
1
PARP(91)
2.1
2.1
2.1
PARP(93)
15.0
15.0
15.0
Intrinsic KT
CDF Paper Seminar
Fermilab - March 11, 2010
Rick Field – Florida/CDF/CMS
Page 2
All use LO as
with L = 192 MeV!
UE Parameters
Tune A
ISR Parameter
PYTHIA 6.2 Tunes
Parameter
Tune DWT
Tune D6T
ATLAS
PDF
CTEQ5L
CTEQ6L
CTEQ5L
MSTP(81)
1
1
1
MSTP(82)
4
4
4
PARP(82)
1.9409 GeV
1.8387 GeV
1.8 GeV
PARP(83)
0.5
0.5
0.5
ATLAS energy dependence!
PARP(84)
0.4
0.4
Tune
B 0.5
Tune
AW
Tune BW
These are “old”
PYTHIA
6.20.33tunes!
PARP(85)
1.0
1.0
There are
tunes
PARP(86)
1.0 new 6.420
1.0
0.66 by
PARP(89)Skands
1.96 TeV
TeV update
1.0 TeV of S0)
Peter
(Tune1.96
S320,
PARP(90)
0.16
0.16 N324, 0.16
Peter Skands
(Tune
N0CR)
PARP(62)
1.25
1.25
1.0
Hendrik Hoeth (Tune P329, “Professor”)
PARP(64)
0.2
0.2
1.0
PARP(67)
2.5
2.5
1.0
MSTP(91)
1
1
1
PARP(91)
Tune D
PARP(93)
Tune 2.1
DW
15.0
2.1
15.0
5.0
Tune D6T
Intrinsic KT
CDF Paper Seminar
Fermilab - March 11, 2010
1.0
Tune D6
CMS
Rick Field – Florida/CDF/CMS
Page 3
QCD Monte-Carlo Models:
High Transverse Momentum Jets
Hard Scattering
Initial-State Radiation
Hard Scattering “Jet”
Initial-State Radiation
“Jet”
Outgoing Parton
PT(hard)
Outgoing Parton
PT(hard)
Proton
“Hard Scattering” Component
AntiProton
Final-State Radiation
Outgoing Parton
Underlying Event
Underlying Event
Proton
“Jet”
Final-State Radiation
AntiProton
Underlying Event
Outgoing Parton
Underlying Event
“Underlying Event”
 Start with the perturbative 2-to-2 (or sometimes 2-to-3) parton-parton scattering and add initial and finalstate gluon radiation (in the leading log approximation or modified leading log approximation).
 The “underlying event” consists of the “beam-beam remnants” and from particles arising from soft or
semi-soft multiple parton interactions (MPI).
The “underlying
event” is“jet”
an unavoidable
 Of course the outgoing colored partons fragment
into hadron
and inevitably “underlying event”
background to most collider observables
observables receive contributions from initial
and final-state radiation.
and having good understand of it leads to
more precise collider measurements!
CDF Paper Seminar
Fermilab - March 11, 2010
Rick Field – Florida/CDF/CMS
Page 4
QCD Monte-Carlo Models:
Lepton-Pair Production
Lepton-Pair
Production
High
PT Z-Boson
Production
Anti-Lepton
Outgoing Parton
Initial-State
Initial-State Radiation
Radiation
High P
T Z-Boson Production
Lepton-Pair
Production
Initial-State
Initial-StateRadiation
Radiation
“Jet”
Proton
Proton
Final-State Radiation
Outgoing
Parton
Anti-Lepton
Final-State Radiation
“Hard Scattering” Component
AntiProton
AntiProton
Underlying Event
Lepton
Z-boson
Underlying Event
Proton
Lepton
Z-boson
AntiProton
Underlying Event
Underlying Event
“Underlying Event”
 Start with the perturbative Drell-Yan muon pair production and add initial-state gluon radiation (in the
leading log approximation or modified leading log approximation).
 The “underlying event” consists of the “beam-beam remnants” and from particles arising from soft or
semi-soft multiple parton interactions (MPI).
 Of course the outgoing colored partons fragment into hadron “jet” and inevitably “underlying event”
observables receive contributions from initial-state radiation.
CDF Paper Seminar
Fermilab - March 11, 2010
Rick Field – Florida/CDF/CMS
Page 5
“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
“Toward-Side” Jet
2
Away Region
Z-Boson
Direction
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).
 Define || < 60o as “Toward”, 60o < || < 120o as “Transverse ”, and || > 120o as “Away”.
o
Each of the three regions have area  = 2×120 = 4/3.
CDF Paper Seminar
Fermilab - March 11, 2010
Rick Field – Florida/CDF/CMS
Page 6
“Towards”, “Away”, “Transverse”
“Leading Jet”
Jet #1 Direction

“Toward”
“Transverse”
“Transverse”
“Away”
Charged
PTsum
Density
(GeV/c)
Average
Charged
Density
Charged PTsum
ParticleDensity:
Density:dPT/dd
dN/dd
Charged
5
100.0
CDFCDF
RunRun
2 Preliminary
2 Preliminary
4
data corrected
data corrected
pyA generator level
pyA generator level
10.0
3
"Toward"
"Away"
"Toward"
"Away"
Factor of ~16
"Transverse" "Leading Jet"
Factor of MidPoint
~4.5 R=0.7 |(jet#1)|<2
2
1.0
"Transverse"
1
"Leading Jet"
MidPoint R=0.7 |(jet#1)|<2
ChargedParticles
Particles(||<1.0,
(||<1.0,PT>0.5
PT>0.5GeV/c)
GeV/c)
Charged
0 0.1
0 0
50 50
100100
150
150
200
200
250
250
300
300
350
350
400
400
PT(jet#1)
PT(jet#1)(GeV/c)
(GeV/c)
 Data
Data at
at 1.96
1.96 TeV
TeV on
on the
the charged
density ofparticle
charged
particles,
dN/dd,
pT > 0.5with
GeV/c
< 1 for

scalar
pT sum
density, with
dPT/dd,
pT >and
0.5||
GeV/c
and“leading
|| < 1
jet”“leading
events asjet”
a function
ofathe
leadingofjet
for thejet
“toward”,
“away”,
and“away”,
“transverse”
regions. The
for
events as
function
thepTleading
pT for the
“toward”,
and “transverse”
data are corrected
to the
particletolevel
errors
include
statistical
and the systematic
regions.
The data are
corrected
the (with
particle
levelthat
(with
errorsboth
thatthe
include
both error
the statistical
error and
uncertainty)
and
are
compared
with
PYTHIA
Tune
A
at
the
particle
level
(i.e.
generator
level).
the systematic uncertainty) and are compared with PYTHIA Tune A at the particle level (i.e. generator
level).
Rick & Craig
CDF Paper Seminar
Fermilab - March 11, 2010
Rick Field – Florida/CDF/CMS
Page 7
“Towards”, “Away”, “Transverse”
“Drell-Yan Producetion”
ParticleDensity:
Density:dPT/dd
dN/dd
Charged PTsum
Z-Boson Direction

“Toward”
“Transverse”
“Transverse”
“Away”
Average
Charged
Density
Charged
PTsum
Density
(GeV/c)
310.0
CDF
Run
2 Preliminary
CDF
Run
2 Preliminary
corrected
datadata
corrected
pyAW
generator
pyAW
generator
levellevel
2
"Away"
"Away"
Factor of ~11
"Drell-Yan Production"
70 < M(pair) < 110 GeV
"Transverse"
1.0
1
Factor of ~3
"Toward"
"Transverse"
"Drell-Yan Production"
70 < M(pair) < 110 GeV
"Toward"
0 0.1
0 0
20 20
4040
Charged Particles (||<1.0, PT>0.5 GeV/c)
Charged Particles (||<1.0, PT>0.5 GeV/c)
excluding the lepton-pair
excluding the lepton-pair
6060
80
80
100
PT(Z-Boson)
PT(Z-Boson)(GeV/c)
(GeV/c)

charged
particles,
dN/dd,
pT > 0.5with
GeV/c
< 1 for
 Data
Data at
at 1.96
1.96 TeV
TeV on
on the
the density
chargedofparticle
scalar
pT sum
density,with
dPT/dd,
pT >and
0.5||
GeV/c
and“Z|| < 1
Boson”
events as
a function
of the leading
jet pT for
“toward”,
“away”,“away”,
and “transverse”
regions. The
for “Z-Boson”
events
as a function
of the leading
jetthe
pT for
the “toward”,
and “transverse”
data
are corrected
to the
particletolevel
errors
include
statistical
and the systematic
regions.
The data are
corrected
the (with
particle
levelthat
(with
errorsboth
thatthe
include
both error
the statistical
error and
uncertainty)
are compared
withcompared
PYTHIAwith
TunePYTHIA
AW at the
particle
level
generator
level).
the systematicand
uncertainty)
and are
Tune
AW at
the(i.e.
particle
level (i.e.
generator
level).
Deepak Kar’s Thesis
CDF Paper Seminar
Fermilab - March 11, 2010
Rick Field – Florida/CDF/CMS
Page 8
Charged Particle Multiplicity
Charged Multiplicity Distribution
Charged Multiplicity Distribution
1.0E+00
1.0E+00
CDF Run 2 Preliminary
CDF Run 2 Preliminary
1.0E-01
1.0E-01
CDF Run 2 <Nchg>=4.5
CDF Run 2 <Nchg>=4.5
1.0E-02
1.0E-02
1.0E-03
1.0E-03
py64 Tune A <Nchg> = 4.1
Probability
Probability
pyAnoMPI <Nchg> = 2.6
1.0E-04
1.0E-05
1.0E-04
1.0E-05
1.0E-06
1.0E-06
HC 1.96 TeV
Min-Bias 1.96 TeV
1.0E-07
1.0E-07
Normalized to 1
Normalized to 1 Charged Particles (||<1.0, PT>0.4 GeV/c)
Charged Particles (||<1.0, PT>0.4 GeV/c)
1.0E-08
1.0E-08
0
5
10
15
20
25
30
35
40
45
50
55
0
5
20
25
30
35
40
No MPI!
“Minumum Bias” Collisions
Proton
15
45
50
55
Number of Charged Particles
Number of Charged Particles
7 decades!
10
Tune A!
AntiProton
 Data at 1.96 TeV on the charged particle multiplicity (pT > 0.4 GeV/c, || < 1) for “min-bias”
collisions at CDF Run 2.
 The data are compared with PYTHIA Tune A and Tune A without multiple parton
interactions (pyAnoMPI).
CDF Paper Seminar
Fermilab - March 11, 2010
Rick Field – Florida/CDF/CMS
Page 9
The “Underlying Event”
Select inelastic non-diffractive events
that contain a hard scattering
Proton
Hard parton-parton
collisions is hard
(pT > ≈2 GeV/c)
Proton
The “underlying-event” (UE)!
Proton
Given that you have one hard
scattering it is more probable to
have MPI! Hence, the UE has
more activity than “min-bias”.
CDF Paper Seminar
Fermilab - March 11, 2010
“Semi-hard” partonparton collision
(pT < ≈2 GeV/c)
Proton
+
+
Proton
Proton
Rick Field – Florida/CDF/CMS
Proton
Proton
+…
Multiple-parton
interactions (MPI)!
Page 10
The Inelastic Non-Diffractive
Cross-Section
Occasionally one of
the parton-parton
collisions is hard
(pT > ≈2 GeV/c)
Proton
Proton
Majority of “minbias” events!
Proton
“Semi-hard” partonparton collision
(pT < ≈2 GeV/c)
Proton
+
Proton
+
Proton
Proton
Proton
+
Proton
Proton
+…
CDF Paper Seminar
Fermilab - March 11, 2010
Rick Field – Florida/CDF/CMS
Multiple-parton
interactions (MPI)!
Page 11
The “Underlying Event”
Select inelastic non-diffractive events
that contain a hard scattering
Proton
Hard parton-parton
collisions is hard
(pT > ≈2 GeV/c)
Proton
The “underlying-event” (UE)!
Proton
Given that you have one hard
scattering it is more probable to
have MPI! Hence, the UE has
more activity than “min-bias”.
CDF Paper Seminar
Fermilab - March 11, 2010
“Semi-hard” partonparton collision
(pT < ≈2 GeV/c)
Proton
+
+
Proton
Proton
Rick Field – Florida/CDF/CMS
Proton
Proton
+…
Multiple-parton
interactions (MPI)!
Page 12
Min-Bias Correlations
Average PT versus Nchg
Average PT (GeV/c)
1.4
CDF Run 2 Preliminary
pyDW
data corrected
generator level theory
“Minumum Bias” Collisions
1.2
Min-Bias
1.96 TeV
pyA
Proton
1.0
AntiProton
ATLAS
0.8
Charged Particles (||<1.0, PT>0.4 GeV/c)
0.6
0
10
20
30
40
50
Number of Charged Particles
 Data at 1.96 TeV on the average pT of charged particles versus the number of charged
particles (pT > 0.4 GeV/c, || < 1) for “min-bias” collisions at CDF Run 2. The data are
corrected to the particle level and are compared with PYTHIA Tune A at the particle
level (i.e. generator level).
CDF Paper Seminar
Fermilab - March 11, 2010
Rick Field – Florida/CDF/CMS
Page 13
Min-Bias: Average PT versus Nchg
 Beam-beam remnants (i.e. soft hard core) produces
Average PT versus Nchg
Average PT (GeV/c)
1.4
CDF Run 2 Preliminary
Min-Bias
1.96 TeV
data corrected
generator level theory
1.2
low multiplicity and small <pT> with <pT>
independent of the multiplicity.
 Hard scattering (with no MPI) produces large
pyA
multiplicity and large <pT>.
pyAnoMPI
1.0
 Hard scattering (with MPI) produces large
0.8
multiplicity and medium <pT>.
ATLAS
Charged Particles (||<1.0, PT>0.4 GeV/c)
0.6
0
5
10
15
20
25
30
35
40
This observable is sensitive
to the MPI tuning!
Number of Charged Particles
“Hard” Hard Core (hard scattering)
Outgoing Parton
“Soft” Hard Core (no hard scattering)
PT(hard)
CDF “Min-Bias”
=
Proton
+
AntiProton
Proton
AntiProton
Underlying Event
Underlying Event
Initial-State
Radiation
Final-State
Radiation
Multiple-Parton Interactions
+
Proton
AntiProton
Underlying Event
Outgoing Parton
CDF Paper Seminar
Fermilab - March 11, 2010
Outgoing Parton
PT(hard)
Initial-State
Radiation
The CDF “min-bias” trigger
picks up most of the “hard
core” component!
Outgoing Parton
Underlying Event
Final-State
Radiation
Rick Field – Florida/CDF/CMS
Page 14
Average PT versus Nchg
Average PT
PT versus
versus Nchg
Nchg
Average
Average PT versus Nchg
2.5
2.5
CDF Run 2 Preliminary
data corrected
generator level theory
1.2
CDFRun
Run22Preliminary
Preliminary
CDF
Min-Bias
1.96 TeV
Average
Average PT
PT (GeV/c)
(GeV/c)
Average PT (GeV/c)
1.4
pyA
pyAnoMPI
1.0
0.8
ATLAS
data corrected
generator
level theory
generator level theory
2.0
2.0
HW
HW
pyAW
pyAW
"Drell-YanProduction"
Production"
"Drell-Yan
70<<M(pair)
M(pair)<<110
110GeV
GeV
70
1.5
1.5
JIM
JIM
1.0
1.0
ATLAS
ATLAS
Charged Particles (||<1.0, PT>0.4 GeV/c)
0.6
ChargedParticles
Particles(||<1.0,
(||<1.0,PT>0.5
PT>0.5GeV/c)
GeV/c)
Charged
excludingthe
thelepton-pair
lepton-pair
excluding
0.5
0.5
0
5
10
15
20
25
30
35
40
00
55
10
10
Number of Charged Particles
15
15
20
20
25
25
30
30
Numberof
ofCharged
ChargedParticles
Particles
Number
Drell-Yan Production
Lepton
“Minumum Bias” Collisions
Proton
AntiProton
Proton
AntiProton
Underlying Event
Underlying Event
Anti-Lepton
 Data at 1.96 TeV on the average pT of charged particles versus the number of charged particles (pT > 0.4 GeV/c, || <
1) for “min-bias” collisions at CDF Run 2. The data are corrected to the particle leveland are compared with PYTHIA
Tune A, Tune DW, and the ATLAS tune at the particle level (i.e. generator level).
 Particle level predictions for the average pT of charged particles versus the number of charged particles (pT > 0.5
GeV/c, || < 1, excluding the lepton-pair) for for Drell-Yan production (70 < M(pair) < 110 GeV) at CDF Run 2.
CDF Paper Seminar
Fermilab - March 11, 2010
Rick Field – Florida/CDF/CMS
Page 15
35
35
Average PT versus Nchg
 Z-boson production (with low pT(Z) and no MPI)
No MPI!
Average PT versus Nchg
produces low multiplicity and small <pT>.
2.5
Average PT (GeV/c)
CDF Run 2 Preliminary
data corrected
generator level theory
2.0
HW
 High pT Z-boson production produces large
pyAW
multiplicity and high <pT>.
"Drell-Yan Production"
70 < M(pair) < 110 GeV
 Z-boson production (with MPI) produces large
1.5
multiplicity and medium <pT>.
JIM
1.0
ATLAS
Charged Particles (||<1.0, PT>0.5 GeV/c)
excluding the lepton-pair
0.5
0
5
10
15
20
25
30
35
Number of Charged Particles
Drell-Yan Production (no MPI)
High PT Z-Boson Production
Lepton
Initial-State Radiation
Outgoing Parton
Final-State Radiation
Drell-Yan
=
Proton
AntiProton
Underlying Event
Underlying Event
Anti-Lepton
+
+
Drell-Yan Production (with MPI)
Proton
Proton
Lepton
AntiProton
Z-boson
AntiProton
Underlying Event
Underlying Event
Anti-Lepton
CDF Paper Seminar
Fermilab - March 11, 2010
Rick Field – Florida/CDF/CMS
Page 16
Average PT(Z) versus Nchg
No MPI!
Average PT versus Nchg
PT(Z-Boson)
PT(Z-Boson) versus
versus Nchg
Nchg
80
80
2.5
data corrected
generator level theory
2.0
CDF
CDF Run
Run 22 Preliminary
Preliminary
HW
Average PT(Z) (GeV/c)
Average PT (GeV/c)
CDF Run 2 Preliminary
pyAW
"Drell-Yan Production"
70 < M(pair) < 110 GeV
1.5
JIM
1.0
ATLAS
generator
level theory
data corrected
generator level theory
60
60
pyAW
pyAW
HW
HW
"Drell-Yan
"Drell-Yan Production"
Production"
70
70 << M(pair)
M(pair) << 110
110 GeV
GeV
40
40
JIM
JIM
20
20
Charged Particles (||<1.0, PT>0.5 GeV/c)
excluding the lepton-pair
ATLAS
ATLAS
Charged
Charged Particles
Particles (||<1.0,
(||<1.0, PT>0.5
PT>0.5 GeV/c)
GeV/c)
excluding
excluding the
the lepton-pair
lepton-pair
00
0.5
0
5
10
15
20
25
30
35
00
55
Outgoing Parton
Lepton
Initial-State Radiation
Proton
Proton
AntiProton
Underlying Event
Underlying Event
15
15
20
20
25
25
30
30
35
35
40
40
Number
Number of
of Charged
Charged Particles
Particles
Number of Charged Particles
High PDrell-Yan
Production
T Z-BosonProduction
10
10
 Predictions for the average PT(Z-Boson) versus
the number of charged particles (pT > 0.5
GeV/c, || < 1, excluding the lepton-pair) for for
Drell-Yan production (70 < M(pair) < 110 GeV)
at CDF Run 2.
Anti-Lepton
Z-boson
 Data on the average pT of charged particles versus the number of charged particles (pT > 0.5 GeV/c, || < 1,
excluding the lepton-pair) for for Drell-Yan production (70 < M(pair) < 110 GeV) at CDF Run 2. The data are
corrected to the particle level and are compared with various Monte-Carlo tunes at the particle level (i.e.
generator level).
CDF Paper Seminar
Fermilab - March 11, 2010
Rick Field – Florida/CDF/CMS
Page 17
Average PT versus Nchg
PT(Z) < 10 GeV/c
Average
Charged
PT
versus
Nchg
Average
Average Charged
Charged PT
PT versus
versus Nchg
Nchg
CDF
Run
Preliminary
CDF
CDF Run
Run 22
2 Preliminary
Preliminary
data corrected
generator
level
generator
level theory
theory
generator level theory
1.2
1.2
1.2
pyAW
pyAW
pyAW
1.0
1.0
1.0
HW
HW
HW
0.8
0.8
0.8
"Drell-Yan
Production"
"Drell-Yan
"Drell-Yan Production"
Production"
70
M(pair)
110
GeV
70
70 <<
< M(pair)
M(pair) <<
< 110
110 GeV
GeV
PT(Z)
10
GeV/c
PT(Z)
PT(Z) <<
< 10
10 GeV/c
GeV/c
ATLAS
ATLAS
CDF Run 2 Preliminary
JIM
JIM
Average PT (GeV/c)
Average
PT
(GeV/c)
AveragePT
PT(GeV/c)
(GeV/c)
Average
1.4
1.4
1.4
Average PT versus Nchg
1.4
Drell-Yan PT > 0.5 GeV PT(Z) < 10 GeV/c
data corrected
generator level theory
1.2
pyAW
No MPI!
1.0
Min-Bias PT > 0.4 GeV/c
0.8
It is my fault for being so slow!
It is important that we publish
this paper now!
Charged
Particles
(||<1.0,
PT>0.5
GeV/c)
Charged
Charged Particles
Particles (||<1.0,
(||<1.0, PT>0.5
PT>0.5 GeV/c)
GeV/c)
excluding
the
lepton-pair
excluding
excluding the
the lepton-pair
lepton-pair
Charged Particles (||<1.0)
pyA
0.6
0.6
0.6
0.6
00
0
55
5
10
10
10
15
15
15
20
20
20
25
25
25
30
30
30
35
35
35
0
Number
of
Charged
Particles
Number
Number of
of Charged
Charged Particles
Particles
Drell-Yan Production
Proton
20
30
40
Number of Charged Particles
Lepton
AntiProton
Underlying Event
10
Underlying Event
Remarkably similar behavior!
Perhaps indicating that MPIProton
playing an important role in
both processes.
“Minumum Bias” Collisions
AntiProton
Anti-Lepton
 Predictions
for thepTaverage
pT ofparticles
chargedversus
particles
theofnumber
charged(p
particles
(pT > 0.5
Data the average
of charged
theversus
number
chargedofparticles
||GeV/c,
< 1, ||
T > 0.5 GeV/c,
<
1, excluding
the lepton-pair)
forDrell-Yan
for Drell-Yan
production
< M(pair)
110 GeV,
PT(pair)
10 GeV/c)
at
excluding
the lepton-pair)
for for
production
(70 <(70
M(pair)
< 110< GeV,
PT(pair)
< 10<GeV/c)
at CDF
CDF
Run
Run 2.
The2.data are corrected to the particle level and are compared with various Monte-Carlo tunes at the
particle level (i.e. generator level).
CDF Paper Seminar
Fermilab - March 11, 2010
Rick Field – Florida/CDF/CMS
Page 18