Studying the Underlying Event at
CDF and the LHC
Rick Field
University of Florida
Outline of Talk
 Review what we learned about
“min-bias” and the “underlying
event” in Run 1 at CDF.
LBNL January 13, 2009
 Explain the various PYTHIA “underlying
event” tunes and extrapolations to the
LHC.
 “CDF-QCD Data for Theory”: Studying
the “underlying event” using high pT jet
production and Z-boson production.
Outgoing Parton
PT(hard)
Initial-State Radiation
Proton
AntiProton
Underlying Event
Outgoing Parton
Underlying Event
Final-State
Radiation
R. Field, C. Group, & D. Kar
 Some things I do not understand about the
CDF “underlying event” data.
 UE&MB@CMS: Plans to measure
“min-bias” and the “underlying
event” at CMS.
University of California, Berkeley
January 13, 2009
CMS at the LHC
CDF Run 2
Rick Field – Florida/CDF/CMS
Page 1
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!
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 2
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.
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 3
Proton-AntiProton Collisions
at the Tevatron
Elastic Scattering
The CDF “Min-Bias” trigger
picks up most of the “hard
core” cross-section plus a
Double
Diffraction
small
amount of single &
double diffraction.
M2
M1
Single Diffraction
M
stot = sEL + sIN
SD +sDD +sHC
1.8 TeV: 78mb
= 18mb
+ 9mb
+ (4-7)mb + (47-44)mb
CDF “Min-Bias” trigger
1 charged particle in forward BBC
AND
1 charged particle in backward BBC
Hard Core
The “hard core” component
contains both “hard” and
“soft” collisions.
“Hard” Hard Core (hard scattering)
Outgoing Parton
“Soft” Hard Core (no hard scattering)
Proton
AntiProton
PT(hard)
Beam-Beam Counters
3.2 < |h| < 5.9
Proton
AntiProton
Underlying Event
Underlying Event
Initial-State
Radiation
Final-State
Radiation
Outgoing Parton
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 4
Particle Densities
DhD = 4 = 12.6
2

31 charged
charged particles
particle
Charged Particles
pT > 0.5 GeV/c |h| < 1
CDF Run 2 “Min-Bias”
CDF Run 2 “Min-Bias”
Observable
Average
Nchg
Number of Charged Particles
(pT > 0.5 GeV/c, |h| < 1)
3.17 +/- 0.31
0.252 +/- 0.025
PTsum
(GeV/c)
Scalar pT sum of Charged Particles
(pT > 0.5 GeV/c, |h| < 1)
2.97 +/- 0.23
0.236 +/- 0.018
Average Density
per unit h-
dNchg
chg/dhd = 1/4
3/4 = 0.08
0.24
13 GeV/c PTsum
0
-1
h
+1
Divide by 4
dPTsum/dhd = 1/4
3/4 GeV/c = 0.08
0.24 GeV/c
Study the charged particles (pT > 0.5 GeV/c, |h| < 1) and form the charged
particle density, dNchg/dhd, and the charged scalar pT sum density,
dPTsum/dhd.
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 5
CDF Run 1 “Min-Bias” Data
Charged Particle Density
Charged Particle Density: dN/dhd
Charged Particle Pseudo-Rapidity Distribution: dN/dh
1.0
7
CDF Published
CDF Published
6
0.8
dN/dhd
dN/dh
5
4
3
0.6
0.4
2
0.2
CDF Min-Bias 630 GeV
CDF Min-Bias 1.8 TeV
1
CDF Min-Bias 1.8 TeV
all PT
CDF Min-Bias 630 GeV
all PT
0.0
0
-4
-3
-2
-1
0
1
2
3
4
-4
-3
-1
0
1
2
3
4
Pseudo-Rapidity h
Pseudo-Rapidity h
<dNchg/dh> = 4.2
-2
<dNchg/dhd> = 0.67
 Shows CDF “Min-Bias” data on the number of charged particles per unit pseudo-rapidity
at 630 and 1,800 GeV. There are about 4.2 charged particles per unit h in “Min-Bias”
collisions at 1.8 TeV (|h| < 1, all pT).
DhxD = 1
 Convert to charged particle density, dNchg/dhd, by dividing by 2.
D = 1
There are about 0.67 charged particles per unit h- in “Min-Bias”
0.25
0.67
collisions at 1.8 TeV (|h| < 1, all pT).
 There are about 0.25 charged particles per unit h- in “Min-Bias”
Dh = 1
collisions at 1.96 TeV (|h| < 1, pT > 0.5 GeV/c).
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 6
CDF Run 2 Min-Bias “Associated”
Charged Particle Density
“Associated” densities do
not include PTmax!
Highest pT
charged particle!
Charged Particle Density: dN/dhd
PTmax Direction
PTmax Direction
0.5
D
Correlations in 
Charged Particle Density
CDF Preliminary
Associated Density
PTmax not included
data uncorrected
0.4
D
Charge Density
0.3
0.2
0.1
Min-Bias
Correlations
in 
Charged Particles
(|h|<1.0, PT>0.5 GeV/c)
PTmax
0.0
0
30
60
90
120
150
180
210
240
270
300
330
360
D (degrees)
 Use the maximum pT charged particle in the event, PTmax, to define a direction and look
It is more probable
to find
a particle
at the the “associated”
density, dN
chg/dhd,
in “min-bias” collisions (pT > 0.5 GeV/c, |h| <
accompanying
PTmax
than
it
is
to
1).
find a particle in the central region!
 Shows the data
on the D dependence of the “associated” charged particle density,
dNchg/dhd, for charged particles (pT > 0.5 GeV/c, |h| < 1, not including PTmax) relative
to PTmax (rotated to 180o) for “min-bias” events. Also shown is the average charged
particle density, dNchg/dhd, for “min-bias” events.
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 7
CDF Run 2 Min-Bias “Associated”
Charged Particle Density Rapid rise in the particle
density in the “transverse”
region as PTmax increases!
Associated Particle Density: dN/dhd
PTmaxDirection
Direction
PTmax
D
“Toward”
“Transverse”
“Transverse”
Correlations in 
“Away”
Associated Particle Density
Jet #1
D
PTmax > 2.0 GeV/c
1.0
PTmax > 2.0 GeV/c
PTmax > 1.0 GeV/c
0.8
Charged Particles
(|h|<1.0, PT>0.5 GeV/c)
CDF Preliminary
data uncorrected
PTmax > 0.5 GeV/c
Transverse
Region
0.6
Transverse
Region
0.4
0.2
Jet #2
PTmax
PTmax not included
Min-Bias
0.0
0
30
60
90
120
150
180
210
240
270
300
330
360
D (degrees)
Ave Min-Bias
0.25 per unit h-
PTmax > 0.5 GeV/c
 Shows the data on the D dependence of the “associated” charged particle density,
dNchg/dhd, for charged particles (pT > 0.5 GeV/c, |h| < 1, not including PTmax) relative
to PTmax (rotated to 180o) for “min-bias” events with PTmax > 0.5, 1.0, and 2.0 GeV/c.
 Shows “jet structure” in “min-bias” collisions (i.e. the “birth” of the leading two jets!).
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 8
CDF Run 1: Evolution of Charged Jets
“Underlying Event”
Charged Particle D Correlations
PT > 0.5 GeV/c |h| < 1
Charged Jet #1
Direction
“Transverse” region
very sensitive to the
“underlying event”!
Look at the charged
particle density in the
“transverse” region!
2
“Toward-Side” Jet
D
“Toward”
CDF Run 1 Analysis
Away Region
Charged Jet #1
Direction
D
Transverse
Region
“Toward”
“Transverse”

Leading
Jet
“Transverse”
Toward Region
“Transverse”
“Transverse”
Transverse
Region
“Away”
“Away”
Away Region
“Away-Side” Jet
0
-1
h
+1
 Look at charged particle correlations in the azimuthal angle D relative to the leading charged
particle jet.
 Define |D| < 60o as “Toward”, 60o < |D| < 120o as “Transverse”, and |D| > 120o as “Away”.
 All three regions have the same size in h- space, DhxD = 2x120o = 4/3.
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 9
Run 1 Charged Particle Density
“Transverse” pT Distribution
"Transverse" Charged Particle Density: dN/dhd
Charged Particle Density
Charged Particle Jet #1
Direction
"Transverse"
PT(chgjet#1) > 5 GeV/cD
1.0E+00
CDF Min-Bias
CDF Run 1
CDF JET20
data uncorrected
0.75
0.50
Factor of 2!
0.25
1.8 TeV |h|<1.0 PT>0.5 GeV/c
0.00
0
5
10
15
20
25
30
35
40
45
PT(charged jet#1) (GeV/c)
PT(charged jet#1) > 30 GeV/c
“Transverse” <dNchg/dhd> = 0.56
“Min-Bias”
50
Charged Density dN/dhddPT (1/GeV/c)
"Transverse" Charged Density
1.00
CDF Run 1
data uncorrected
1.0E-01
“Toward”
"Transverse"
PT(chgjet#1) > 30 GeV/c
1.0E-02
“Transverse”
“Transverse”
1.0E-03
“Away”
1.0E-04
Min-Bias
1.0E-05
1.8 TeV |h|<1 PT>0.5 GeV/c
1.0E-06
CDF Run 1 Min-Bias data
<dNchg/dhd> = 0.25
0
2
4
6
8
10
12
14
PT(charged) (GeV/c)
 Compares the average “transverse” charge particle density with the average “Min-Bias”
charge particle density (|h|<1, pT>0.5 GeV). Shows how the “transverse” charge particle
density and the Min-Bias charge particle density is distributed in pT.
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 10
ISAJET 7.32
“Transverse” Density
ISAJET uses a naïve leading-log
parton shower-model which does
not agree with the data!
Charged Jet #1
Direction
1.00
D
“Transverse”
“Transverse”
“Away”
CDF Run 1Data
"Transverse" Charged Density
“Toward”
ISAJET
"Transverse" Charged Particle Density: dN/dhd
Isajet
data uncorrected
theory corrected
0.75
"Hard"
0.50
0.25
“Hard”
Component
"Remnants"
1.8 TeV |h|<1.0 PT>0.5 GeV
Beam-Beam
Remnants
0.00
0
5
10
15
20
25
30
35
40
45
50
PT(charged jet#1) (GeV/c)
 Plot shows average “transverse” charge particle density (|h|<1, pT>0.5 GeV) versus PT(charged jet#1)
compared to the QCD hard scattering predictions of ISAJET 7.32 (default parameters with
PT(hard)>3 GeV/c) .
 The predictions of ISAJET are divided into two categories: charged particles that arise from the
break-up of the beam and target (beam-beam remnants); and charged particles that arise from the
outgoing jet plus initial and final-state radiation (hard scattering component).
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 11
HERWIG 6.4
“Transverse” Density
HERWIG uses a modified leadinglog parton shower-model which
does agrees better with the data!
"Transverse" Charged Particle Density: dN/dhd
Charged Jet #1
Direction
“Toward”
“Transverse”
“Transverse”
“Away”
CDF Run 1Data
"Transverse" Charged Density
D
1.00
Total
"Hard"
data uncorrected
theory corrected
0.75
0.50
0.25
"Remnants"
Beam-Beam
Remnants
HERWIG
Herwig 6.4 CTEQ5L
PT(hard) > 3 GeV/c
1.8 TeV |h|<1.0 PT>0.5 GeV
0.00
0
5
10
15
20
25
30
PT(charged jet#1) (GeV/c)
35
40
45
50
“Hard”
Component
 Plot shows average “transverse” charge particle density (|h|<1, pT>0.5 GeV) versus PT(charged
jet#1) compared to the QCD hard scattering predictions of HERWIG 5.9 (default parameters with
PT(hard)>3 GeV/c).
 The predictions of HERWIG are divided into two categories: charged particles that arise from the
break-up of the beam and target (beam-beam remnants); and charged particles that arise from the
outgoing jet plus initial and final-state radiation (hard scattering component).
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 12
HERWIG 6.4
“Transverse” PT Distribution
HERWIG has the too steep of a pT
dependence of the “beam-beam remnant”
"Transverse" Chargedcomponent
Particle Density:
dN/dhd
of the
“underlying event”!
"Transverse" Charged Particle Density
Charged Jet #1
Direction
CDF Data
"Hard"
Total
data uncorrected
theory corrected
0.75
1.0E+00
Herwig 6.4 CTEQ5L
PT(hard) > 3 GeV/c
D
0.50
0.25
"Remnants"
1.8 TeV |h|<1.0 PT>0.5 GeV
0.00
0
5
10
CDF Data
PT(chgjet#1) > 5 GeV/c
15
20
25
30
35
40
45
PT(charged jet#1) (GeV/c)
Herwig PT(chgjet#1) > 30 GeV/c
“Transverse” <dNchg/dhd> = 0.51
50
Charged Density dN/dhddPT (1/GeV/c)
"Transverse" Charged Density
1.00
data uncorrected
theory corrected
1.0E-01
“Toward”
1.8 TeV |h|<1 PT>0.5 GeV/c
1.0E-02
“Transverse”
1.0E-03
“Transverse”
“Away”
1.0E-04
1.0E-05
PT(chgjet#1) > 30 GeV/c
Herwig 6.4 CTEQ5L
1.0E-06
Herwig PT(chgjet#1) > 5 GeV/c
<dNchg/dhd> = 0.40
0
2
4
6
8
10
12
14
PT(charged) (GeV/c)
 Compares the average “transverse” charge particle density (|h|<1, pT>0.5 GeV) versus
PT(charged jet#1) and the pT distribution of the “transverse” density, dNchg/dhddPT with the
QCD hard scattering predictions of HERWIG 6.4 (default parameters with PT(hard)>3 GeV/c.
Shows how the “transverse” charge particle density is distributed in pT.
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 13
MPI: Multiple Parton
Interactions
“Hard”
Collision
Multiple
Parton
Interaction
outgoing parton
“Hard” Component
“Semi-Hard” MPI
“Soft” Component
AntiProton
Proton
initial-state radiation
initial-state radiation
outgoing parton
final-state radiation
or
+
outgoing jet
final-state radiation
 PYTHIA models the “soft” component of the underlying event
with color string fragmentation, but in addition includes a
contribution arising from multiple parton interactions (MPI) in
which one interaction is hard and the other is “semi-hard”.
Beam-Beam Remnants
color string
color string
 The probability that a hard scattering events also contains a semi-hard multiple parton
interaction can be varied but adjusting the cut-off for the MPI.
 One can also adjust whether the probability of a MPI depends on the PT of the hard
scattering, PT(hard) (constant cross section or varying with impact parameter).
 One can adjust the color connections and flavor of the MPI (singlet or nearest neighbor,
q-qbar or glue-glue).
 Also, one can adjust how the probability of a MPI depends on PT(hard) (single or double
Gaussian matter distribution).
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 14
Tuning PYTHIA:
Multiple Parton Interaction Parameters
Parameter
Default
Description
PARP(83)
0.5
Double-Gaussian: Fraction of total hadronic
matter within PARP(84)
PARP(84)
0.2
Double-Gaussian: Fraction of the overall hadron
radius containing the fraction PARP(83) of the
total hadronic matter.
Multiple Parton Interaction
Color String
Color String
PARP(86)
PARP(89)
PARP(90)
PARP(67)
0.33
0.66
1 TeV
0.16
1.0
Probability that the MPI produces two gluons
with color connections to the “nearest neighbors.
Multiple PartonDetermine
Interactionby comparing
with 630 GeV data!
Probability that the MPI produces two gluons
either as described by PARP(85) or as a closed
gluon
loop.
remaining
fraction consists of
Affects
the The
amount
of
quark-antiquark
pairs.
initial-state radiation!
Color String
Hard-Scattering Cut-Off PT0
5
Determines the reference energy E0.
Determines the energy dependence of the cut-off
PT0 as follows PT0(Ecm) = PT0(Ecm/E0)e with
e = PARP(90)
A scale factor that determines the maximum
parton virtuality for space-like showers. The
larger the value of PARP(67) the more initialstate radiation.
PYTHIA 6.206
e = 0.25 (Set A))
4
PT0 (GeV/c)
PARP(85)
Take E0 = 1.8 TeV
3
2
e = 0.16 (default)
1
100
1,000
10,000
100,000
CM Energy W (GeV)
Reference point
at 1.8 TeV
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 15
PYTHIA 6.206 Defaults
MPI constant
probability
scattering
PYTHIA default parameters
6.115
6.125
6.158
6.206
MSTP(81)
1
1
1
1
MSTP(82)
1
1
1
1
PARP(81)
1.4
1.9
1.9
1.9
PARP(82)
1.55
2.1
2.1
1.9
PARP(89)
1,000
1,000
1,000
PARP(90)
0.16
0.16
0.16
4.0
1.0
1.0
PARP(67)
4.0
1.00
"Transverse" Charged Density
Parameter
"Transverse" Charged Particle Density: dN/dhd
CDF Data
Pythia 6.206 (default)
MSTP(82)=1
PARP(81) = 1.9 GeV/c
data uncorrected
theory corrected
0.75
0.50
0.25
1.8 TeV |h|<1.0 PT>0.5 GeV
0.00
0
5
10
15
20
25
30
35
40
45
50
PT(charged jet#1) (GeV/c)
CTEQ3L
CTEQ4L
CTEQ5L
CDF Min-Bias
CDF JET20
 Plot shows the “Transverse” charged particle density versus PT(chgjet#1) compared to the
QCD hard scattering predictions of PYTHIA 6.206 (PT(hard) > 0) using the default
parameters for multiple parton interactions and CTEQ3L, CTEQ4L, and CTEQ5L.
Note Change
PARP(67) = 4.0 (< 6.138)
PARP(67) = 1.0 (> 6.138)
University of California, Berkeley
January 13, 2009
Default parameters give
very poor description of
the “underlying event”!
Rick Field – Florida/CDF/CMS
Page 16
Run 1 PYTHIA Tune A
CDF Default!
PYTHIA 6.206 CTEQ5L
"Transverse" Charged Particle Density: dN/dhd
Parameter
Tune B
Tune A
MSTP(81)
1
1
MSTP(82)
4
4
PARP(82)
1.9 GeV
2.0 GeV
PARP(83)
0.5
0.5
PARP(84)
0.4
0.4
PARP(85)
1.0
0.9
"Transverse" Charged Density
1.00
CDF Preliminary
0.75
1.0
0.95
PARP(89)
1.8 TeV
1.8 TeV
PARP(90)
0.25
0.25
PARP(67)
1.0
4.0
New PYTHIA default
(less initial-state radiation)
University of California, Berkeley
January 13, 2009
Run 1 Analysis
0.50
0.25
CTEQ5L
PYTHIA 6.206 (Set B)
PARP(67)=1
1.8 TeV |h|<1.0 PT>0.5 GeV
0.00
0
PARP(86)
PYTHIA 6.206 (Set A)
PARP(67)=4
data uncorrected
theory corrected
5
10
15
20
25
30
35
40
45
50
PT(charged jet#1) (GeV/c)
 Plot shows the “transverse” charged particle density
versus PT(chgjet#1) compared to the QCD hard
scattering predictions of two tuned versions of PYTHIA
6.206 (CTEQ5L, Set B (PARP(67)=1) and Set A
(PARP(67)=4)).
Old PYTHIA default
(more initial-state radiation)
Rick Field – Florida/CDF/CMS
Page 17
PYTHIA Tune A Min-Bias
“Soft” + ”Hard”
Tuned to fit the CDF Run 1
“underlying event”!
PYTHIA Tune A
CDF Run 2 Charged
DefaultParticle Density
Charged Particle Density: dN/dhd
1.0
CDF Published
1.0E+00
0.8
CDF Min-Bias Data
1.0E-01
0.6
0.4
0.2
Pythia 6.206 Set A
1.8 TeV all PT
CDF Min-Bias 1.8 TeV
0.0
-4
-3
-2
-1
0
1
2
3
4
Pseudo-Rapidity h
 PYTHIA regulates the perturbative 2-to-2
parton-parton cross sections with cut-off
parameters
which allows one to run with
Lots of “hard” scattering in
PT“Min-Bias”
(hard) > 0.
One
can simulate both “hard”
at the
Tevatron!
and “soft” collisions in one program.
Charged Density dN/dhddPT (1/GeV/c)
dN/dhd
Pythia 6.206 Set A
1.8 TeV |h|<1
1.0E-02
12% of “Min-Bias” events
have PT(hard) > 5 GeV/c!
PT(hard) > 0 GeV/c
1.0E-03
1% of “Min-Bias” events
have PT(hard) > 10 GeV/c!
1.0E-04
1.0E-05
CDF Preliminary
1.0E-06
0
2
4
6
8
10
12
14
PT(charged) (GeV/c)
 The relative amount of “hard” versus “soft” depends on the cut-off and can be tuned.
 This PYTHIA fit predicts that 12% of all “Min-Bias” events are a result of a hard 2-to-2
parton-parton scattering with PT(hard) > 5 GeV/c (1% with PT(hard) > 10 GeV/c)!
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 18
PYTHIA Tune A
LHC Min-Bias Predictions
Hard-Scattering in Min-Bias Events
Charged Particle Density
50%
12% of “Min-Bias”
events
have|h|<1
PT(hard) > 10 GeV/c!
1.0E+00
Pythia 6.206 Set A
Pythia 6.206 Set A
40%
% of Events
Charged Density dN/dhddPT (1/GeV/c)
1.0E-01
1.0E-02
PT(hard) > 5 GeV/c
PT(hard) > 10 GeV/c
30%
20%
1.8 TeV
1.0E-03
10%
14 TeV
1.0E-04
0%
100
1,000
10,000
100,000
CM Energy W (GeV)
630 GeV
LHC?
1.0E-05
 Shows the center-of-mass energy dependence
CDF Data
1.0E-06
0
2
4
6
8
PT(charged) (GeV/c)
1% of “Min-Bias” events
have PT(hard) > 10 GeV/c!
10
12
14
of the charged particle density,
dNchg/dhddPT, for “Min-Bias” collisions
compared with PYTHIA Tune A with
PT(hard) > 0.
 PYTHIA Tune A predicts that 1% of all “Min-Bias” events at 1.8 TeV are a result of a hard
2-to-2 parton-parton scattering with PT(hard) > 10 GeV/c which increases to 12% at 14 TeV!
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 19
“Towards”, “Away”, “Transverse”
Look at the charged
particle density, the
charged PTsum density
and the ETsum density in
all 3 regions!
D 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 |h| < 1
Calorimeter towers ET > 0.1 GeV |h| < 1
“Toward-Side” Jet
2
Away Region
Z-Boson
Direction
Jet #1 Direction
D
D
Transverse
Region
“Toward”
“Toward”
“Transverse”
“Transverse”
“Away”
“Transverse”
“Transverse”

Leading
Jet
Toward Region
“Away”
Transverse
Region
“Away-Side” Jet
Away Region
0
-1
h
+1
 Look at correlations in the azimuthal angle D relative to the leading charged particle jet (|h| <
1) or the leading calorimeter jet (|h| < 2).
 Define |D| < 60o as “Toward”, 60o < |D| < 120o as “Transverse ”, and |D| > 120o as “Away”.
o
Each of the three regions have area DhD = 2×120 = 4/3.
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 20
Event Topologies
 “Leading Jet” events correspond to the leading
calorimeter jet (MidPoint R = 0.7) in the region |h| < 2
with no other conditions.
 “Inclusive 2-Jet Back-to-Back” events are selected to
have at least two jets with Jet#1 and Jet#2 nearly “backto-back” (D12 > 150o) with almost equal transverse
energies (PT(jet#2)/PT(jet#1) > 0.8) with no other
conditions .
 “Exclusive 2-Jet Back-to-Back” events are selected to
have at least two jets with Jet#1 and Jet#2 nearly “backto-back” (D12 > 150o) with almost equal transverse
energies (PT(jet#2)/PT(jet#1) > 0.8) and PT(jet#3) < 15
GeV/c.
 “Leading ChgJet” events correspond to the leading
charged particle jet (R = 0.7) in the region |h| < 1 with
no other conditions.
 “Z-Boson” events are Drell-Yan events
with 70 < M(lepton-pair) < 110 GeV
with no other conditions.
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Jet #1 Direction
D
“Leading Jet”
“Toward”
“Transverse”
“Transverse”
subset
“Away”
Jet #1 Direction
D
“Inc2J Back-to-Back”
“Toward”
subset
“Transverse”
“Transverse”
“Away”
“Exc2J Back-to-Back”
Jet #2 Direction
ChgJet #1 Direction
D
“Charged Jet”
“Toward”
“Transverse”
“Transverse”
“Away”
Z-Boson Direction
D
“Toward”
Z-Boson
“Transverse”
“Transverse”
“Away”
Page 21
“transMAX” & “transMIN”
Jet #1 Direction
Z-Boson
Direction
Jet #1 Direction
D
Area = 4/6
“transMIN” very sensitive to
the “beam-beam remnants”!
“Toward-Side” Jet
D
“Toward”
“TransMAX”
“Toward”
“TransMIN”
“TransMAX”
“Away”
“TransMIN”
Jet #3
“Away”
“Away-Side” Jet
 Define the MAX and MIN “transverse” regions (“transMAX” and “transMIN”) on an
event-by-event basis with MAX (MIN) having the largest (smallest) density. Each of the
two “transverse” regions have an area in h- space of 4/6.
 The “transMIN” region is very sensitive to the “beam-beam remnant” and the soft
multiple parton interaction components of the “underlying event”.
 The difference, “transDIF” (“transMAX” minus “transMIN”), is very sensitive to the
“hard scattering” component of the “underlying event” (i.e. hard initial and final-state
radiation).
 The overall “transverse” density is the average of the “transMAX” and “transMIN”
densities.
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 22
Observables at the
Particle and Detector Level
“Leading Jet”
Jet #1 Direction
Observable
Particle Level
Detector Level
dNchg/dhd
Number of charged particles
per unit h-
(pT > 0.5 GeV/c, |h| < 1)
Number of “good” charged tracks
per unit h-
(pT > 0.5 GeV/c, |h| < 1)
dPTsum/dhd
Scalar pT sum of charged particles
per unit h-
(pT > 0.5 GeV/c, |h| < 1)
Scalar pT sum of “good” charged tracks per
unit h-
(pT > 0.5 GeV/c, |h| < 1)
<pT>
Average pT of charged particles
(pT > 0.5 GeV/c, |h| < 1)
Average pT of “good” charged tracks
(pT > 0.5 GeV/c, |h| < 1)
PTmax
Maximum pT charged particle
(pT > 0.5 GeV/c, |h| < 1)
Require Nchg ≥ 1
Maximum pT “good” charged tracks
(pT > 0.5 GeV/c, |h| < 1)
Require Nchg ≥ 1
dETsum/dhd
Scalar ET sum of all particles
per unit h-
(all pT, |h| < 1)
Scalar ET sum of all calorimeter towers
per unit h-
(ET > 0.1 GeV, |h| < 1)
PTsum/ETsum
Scalar pT sum of charged particles
(pT > 0.5 GeV/c, |h| < 1)
divided by the scalar ET sum of
all particles (all pT, |h| < 1)
Scalar pT sum of “good” charged tracks
(pT > 0.5 GeV/c, |h| < 1)
divided by the scalar ET sum of
calorimeter towers (ET > 0.1 GeV, |h| < 1)
D
“Toward”
“Transverse”
“Transverse”
“Away”
Jet #1 Direction
D
“Toward”
“Transverse”
“Transverse”
“Away”
Jet #2 Direction
“Back-to-Back”
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 23
CDF Run 1 PT(Z)
Parameter
Tune A
Tune AW
UE Parameters MSTP(81)
1
1
MSTP(82)
4
4
PARP(82)
2.0 GeV
2.0 GeV
PARP(83)
0.5
0.5
PARP(84)
0.4
0.4
PARP(85)
0.9
0.9
PARP(86)
0.95
0.95
PARP(89)
1.8 TeV
1.8 TeV
PARP(90)
0.25
0.25
PARP(62)
1.0
1.25
PARP(64)
1.0
0.2
PARP(67)
4.0
4.0
MSTP(91)
1
1
PARP(91)
1.0
2.1
PARP(93)
5.0
15.0
ISR Parameters
Z-Boson Transverse Momentum
0.12
PT Distribution 1/N dN/dPT
PYTHIA 6.2 CTEQ5L
Tune used by the
CDF-EWK group!
CDF Run 1 Data
PYTHIA Tune A
PYTHIA Tune AW
CDF Run 1
published
0.08
1.8 TeV
Normalized to 1
0.04
0.00
0
2
4
6
8
10
12
14
16
18
Z-Boson PT (GeV/c)
 Shows the Run 1 Z-boson pT distribution (<pT(Z)>
≈ 11.5 GeV/c) compared with PYTHIA Tune A
(<pT(Z)> = 9.7 GeV/c), and PYTHIA Tune AW
(<pT(Z)> = 11.7 GeV/c).
Effective Q cut-off, below which space-like showers are not evolved.
Intrensic KT
The Q2 = kT2 in as for space-like showers is scaled by PARP(64)!
University of California, Berkeley
January 13, 2009
20
Rick Field – Florida/CDF/CMS
Page 24
Jet-Jet Correlations (DØ)
Jet#1-Jet#2 D Distribution
D Jet#1-Jet#2
 MidPoint Cone Algorithm (R = 0.7, fmerge = 0.5)
 L = 150 pb-1 (Phys. Rev. Lett. 94 221801 (2005))
 Data/NLO agreement good. Data/HERWIG agreement
good.
 Data/PYTHIA agreement good provided PARP(67) =
1.0→4.0 (i.e. like Tune A, best fit 2.5).
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 25
CDF Run 1 PT(Z)
PYTHIA 6.2 CTEQ5L
Tune DW
Tune AW
UE Parameters MSTP(81)
1
1
MSTP(82)
4
4
PARP(82)
1.9 GeV
2.0 GeV
PARP(83)
0.5
0.5
PARP(84)
0.4
0.4
PARP(85)
1.0
0.9
PARP(86)
1.0
0.95
PARP(89)
1.8 TeV
1.8 TeV
PARP(90)
0.25
0.25
PARP(62)
1.25
1.25
PARP(64)
0.2
0.2
PARP(67)
2.5
4.0
MSTP(91)
1
1
PARP(91)
2.1
2.1
PARP(93)
15.0
15.0
ISR Parameters
PT Distribution 1/N dN/dPT
Parameter
Z-Boson Transverse Momentum
0.12
CDF Run 1 Data
PYTHIA Tune DW
HERWIG
CDF Run 1
published
0.08
1.8 TeV
Normalized to 1
0.04
0.00
0
2
4
6
8
10
12
14
16
18
20
Z-Boson PT (GeV/c)
 Shows the Run 1 Z-boson pT distribution (<pT(Z)>
≈ 11.5 GeV/c) compared with PYTHIA Tune DW,
and HERWIG.
Tune DW uses D0’s perfered value of PARP(67)!
Intrensic KT
Tune DW has a lower value of PARP(67) and slightly more MPI!
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 26
All use LO as
with L = 192 MeV!
PYTHIA 6.2 Tunes
UE Parameters
ISR Parameter
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
PARP(85)
0.9
1.0
1.0
PARP(86)
0.95
1.0
1.0
PARP(89)
1.8 TeV
1.8 TeV
1.8 TeV
PARP(90)
0.25
0.25
0.25
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
Uses CTEQ6L
Tune A energy dependence!
Intrinsic KT
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 27
All use LO as
with L = 192 MeV!
PYTHIA 6.2 Tunes
UE Parameters
Tune A
ISR Parameter
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
energy dependence!
PARP(84)
0.4
0.4
Tune
B
These
PYTHIA
6.20.5tunes!ATLASTune
Tune
AWare “old”
BW
PARP(85)
1.0
1.0
0.33
There are new 6.4 tunes by
PARP(86)
1.0
1.0
0.66
Arthur
Moraes
(ATLAS)
PARP(89)
1.96 TeV
1.96 TeV
1.0 TeV
Hendrik
Hoeth
(MCnet)
PARP(90)
0.16
0.16
0.16
Peter
Skands
(Tune
S0)
PARP(62)
1.25
1.25
1.0
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
University of California, Berkeley
January 13, 2009
1.0
Tune D6
Rick Field – Florida/CDF/CMS
Page 28
All use LO as
with L = 192 MeV!
PYTHIA 6.2 Tunes
UE Parameters
ISR Parameter
Parameter
Tune H(6.418)
Tune DWT
Tune D6T
ATLAS
PDF
CTEQ5L
CTEQ5L
CTEQ6L
CTEQ5L
MSTP(81)
1
1
1
1
MSTP(82)
4
4
4
4
PARP(82)
2.1 GeV
1.9409 GeV
1.8387 GeV
1.8 GeV
PARP(83)
0.84
0.5
0.5
0.5
PARP(84)
0.5
0.4
0.4
0.5
PARP(85)
0.82
1.0
1.0
0.33
PARP(86)
0.91
1.0
1.0
0.66
PARP(89)
1.0
1.96 TeV
1.96 TeV
1.0 TeV
PARP(90)
0.17
0.16
0.16
0.16
PARP(62)
2.97
1.25
1.25
1.0
PARP(64)
0.12
0.2
0.2
1.0
PARP(67)
2.74
2.5
2.5
1.0
MSTP(91)
1
1
1
1
PARP(91)
2.0
2.1
2.1
1.0
PARP(93)
5.0
15.0
15.0
5.0
Q2 ordered showers, old MPI!
Intrinsic KT
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 29
JIMMY at CDF
JIMMY
Runs with HERWIG and adds
multiple parton interactions!
PT(JIM)= 2.5 GeV/c.
Jet #1 Direction
JIMMY: MPI
J. M. Butterworth
J. R. Forshaw
M. H. Seymour
D
“Toward”
“Transverse”
PT(JIM)= 3.25 GeV/c.
“Transverse”
"Transverse" ETsum Density: dET/dhd
4.0
"Transverse" ETsum Density (GeV)
The Energy in the “Underlying
Event” in High PT Jet Production
JIMMY was tuned to fit
the energy density in the
“transverse” region for
“leading jet” events!
JIMMY Default
1.96 TeV
HW
3.0
2.0
PY Tune A
JM325
"Leading Jet"
1.0
CDF Run 2 Preliminary
MidPoint R = 0.7 |h(jet)| < 2
The Drell-Yan JIMMY Tune
PTJIM = 3.6 GeV/c,
PT(particle jet#1) (GeV/c)
JMRAD(73) = 1.8
"Transverse" PTsum Density: dPT/dhd
JMRAD(91) = 1.8
generator level theory
All Particles (|h|<1.0)
0.0
0
“Away”
Outgoing Parton
Initial-State Radiation
AntiProton
Underlying Event
Outgoing Parton
Underlying Event
Final-State
Radiation
"Transverse" PTsum Density (GeV/c)
1.6
PT(hard)
Proton
100
200
300
400
500
JIMMY Default
1.96 TeV
1.2
JM325
PY Tune A
0.8
"Leading Jet"
HW
0.4
MidPoint R = 0.7 |h(jet)| < 2
CDF Run 2 Preliminary
generator level theory
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
“Transverse” <Densities> vs PT(jet#1)
University of California, Berkeley
January 13, 2009
0
50
Rick Field – Florida/CDF/CMS
100
150
200
250
300
350
400
450
500
PT(particle jet#1) (GeV/c)
Page 30
Overall Totals (|h| < 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
D
PTsum (GeV/c)
Average
100
“Overall”
Nchg
"Leading Jet"
MidPoint R=0.7 |h(jet#1)|<2
10
PTsum = 190 GeV/c
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
Stable Particles (|h|<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, |h| < 1) and the overall
scalar pT sum of charged particles (pT > 0.5 GeV/c, |h| < 1) and the overall scalar ET sum of all
particles (|h| < 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)..
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 31
“Towards”, “Away”, “Transverse”
“Leading Jet”
Jet #1 Direction
D
“Toward”
“Transverse”
“Transverse”
“Away”
ETsum
Density
(GeV)
Charged
PTsum
Density
(GeV/c)
Average
Charged
Density
Charged
Particle
Density:
dN/dhd
Charged
PTsum
Density:
dPT/dhd
ETsum
Density:
dET/dhd
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 |h(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 |h(jet#1)|<2
MidPoint R=0.7 |h(jet#1)|<2
ChargedStable
Particles
(|h|<1.0,
PT>0.5
GeV/c)
Charged
Particles
(|h|<1.0,
PT>0.5
GeV/c)
Particles
(|h|<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
Data at
at 1.96
1.96 TeV
TeV on
on the
the charged
density ofparticle
charged
particles,
dN/dhd,
p > 0.5 GeV/c
and |h| < 1 for

pT sum
density, with
dPT/dhd,
and“leading
|h|
T > 0.5 GeV/c

Data at
1.96 TeV
on the
particle scalar
ETscalar
sum density,
dET/dhd,
forT|h| < with
1 for p“leading
jet” events
as<a1
jet” events as a function of the leading jet p for the “toward”, “away”, and “transverse” regions. The
for “leading
jet”
eventsjet
as pa function
of the Tleading
jet pand
the “toward”,
“away”,The
anddata
“transverse”
T for“transverse”
function
of the
leading
“toward”,
“away”,
regions.
are corrected
T for the
data
are
corrected
to
the
particle
level
(with
errors
that
include
both
the
statistical
error
and
the systematic
regions.
The
data
are
corrected
to
the
particle
level
(with
errors
that
include
both
the
statistical
errorand
andare
to the particle level (with errors that include both the statistical error and the systematic uncertainty)
uncertainty)
and
are
compared
with
PYTHIA
Tune
A
at
the
particle
level
(i.e.
generator
level).
the systematic
and A
are
with
PYTHIA
Tune Alevel).
at the particle level (i.e. generator
compared
withuncertainty)
PYTHIA Tune
at compared
the particle
level
(i.e. generator
level).
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 32
Charged Particle Density
HERWIG + JIMMY
Tune
(PTJIM
= 3.6)
Charged
ParticleParticle
Density:Density:
dN/dhd
"Transverse"
Charged
dN/dhdCharged Particle Density:"Away"
Charged
Particle
Density:
dN/dhd
"Away"
dN/dhd
Charged
Particle
Density:
dN/dhd
H. Hoeth, MPI@LHC08
3
CDF Run 2 Preliminary
data corrected
data corrected
generator level theory
pyAW generator level
0.9
2
"Drell-Yan Production"
70 < M(pair) < 110 GeV
0.6
1
"Toward"
0
0.0
00
20
20
40
60
"Leading
Jet"
"Away" data corrected
generator level theory
2
"Drell-Yan Production"
70 < M(pair) < 110 GeV
40
80
Charged Particles
Particles (|h|<1.0,
(|h|<1.0, PT>0.5
PT>0.5
GeV/c)
HW
Charged
GeV/c)
excluding the lepton-pair
100
0
60
120
0
80
160
20
140
180
PT(Z-Boson)
(GeV/c)(GeV/c)
PT(jet#1)
or PT(Z-Boson)
Z-Boson Direction
D
High PT Z-Boson Production
CDF
CDFRun
Run22Preliminary
Preliminary
100
200
40
"Leading Jet"
data
datacorrected
corrected
pyA generator
generator
levellevel
theory
pyAW
1
"Transverse"
"Z-Boson"
0.3
44
Average
Density
"Away" Charged
Charged Density
CDFRun
Run22Preliminary
Preliminary
CDF
"Away" Charged Density
"Transverse"
ChargedDensity
Density
Average Charged
3
1.2
33
"Away"
"Toward"
22
JIM
11
"Leading Jet"
MidPoint R=0.7 |h(jet#1)|<2
"Z-Boson""Transverse"
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
excluding the lepton-pair
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
00
00
60
20
20
40
40
60
60
80
80
80
100
100
100
120
120
140
140
Jet #1 Direction
“Transverse”
PT(hard)
“Toward”
AntiProton
“Transverse”
“Transverse”
200
200
Outgoing Parton
D
Initial-State Radiation
“Toward”
Proton
180
180
PT(jet#1)
or PT(Z-Boson)
PT(jet#1)
(GeV/c) (GeV/c)
PT(Z-Boson) (GeV/c)
Outgoing Parton
160
160
“Transverse”
Initial-State Radiation
Proton
AntiProton
Underlying Event
Underlying Event
“Away”
“Away”
Outgoing Parton
Z-boson
Final-State
Radiation
 Data at 1.96 TeV on the density of charged particles, dN/dhd, with pT > 0.5 GeV/c and |h| < 1 for “Z-Boson”
and “Leading Jet” events as a function of the leading jet pT or PT(Z) 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 AW and Tune A, respectively, at the
particle level (i.e. generator level).
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 33
Charged PTsum Density
12
CDFRun
Run2 2Preliminary
Preliminary
CDF
"Away"
data
corrected
data
corrected
pyAW generator level
generator level theory
1.5
CDF Run 2 Preliminary
data corrected
"Leading Jet"
generator level theory
8
"Transverse"
1.0
1.0
0.5
"Drell-Yan Production"
70 < M(pair) < 110 GeV
"Z-Boson"
0.1
0.0
00
"Drell-Yan Production"
70 < M(pair) < 110 GeV
4 "Toward"
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
excluding the lepton-pair
0
20
40
20
40
80
60
100
60
0
120
80
20
160
140
180
PT(Z-Boson)
(GeV/c)
PT(jet#1)
or PT(Z-Boson)
(GeV/c)
Z-Boson Direction
D
High PT Z-Boson Production
100
40
200
Charged
Density(GeV/c)
(GeV/c)
"Away" PTsum
PTsum Density
10.0
2.0
"Away" PTsum Density (GeV/c)
"Transverse"
PTsumDensity
Density(GeV/c)
(GeV/c)
Charged PTsum
Charged
PTsumPTsum
Density:
dPT/dhd
Charged
PTsum
Density:
dPT/dhd
Charged
PTsum
Density:
dPT/dhd
"Transverse"
Charged
Density:
dPT/dhd
"Away" Charged PTsum Density:"Away"
dPT/dhd
HW
20
100.0
CDF
2 Preliminary
CDF
RunRun
2 Preliminary
15 pyAW
corrected
data data
corrected
pyA generator
level
generator
level theory
"Leading Jet"
"Toward"
10.0
"Away"
"Z-Boson"
10
"Transverse"
JIM
1.0
5
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
excluding the lepton-pair
00.1
0 060 20 20
404080 6060
"Leading Jet"
MidPoint R=0.7 |h(jet#1)|<2
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
8080100100
100
120
120
140
140
Jet #1 Direction
“Transverse”
PT(hard)
“Toward”
AntiProton
“Transverse”
“Transverse”
200
Outgoing Parton
D
Initial-State Radiation
“Toward”
Proton
180
180
PT(jet#1) PT(jet#1)
or PT(Z-Boson)
(GeV/c)(GeV/c)
PT(Z-Boson) (GeV/c)
Outgoing Parton
160
160
“Transverse”
Initial-State Radiation
Proton
AntiProton
Underlying Event
Underlying Event
“Away”
“Away”
Outgoing Parton
Z-boson
Final-State
Radiation
 Data at 1.96 TeV on the charged scalar PTsum density, dPT/dhd, with pT > 0.5 GeV/c and |h| < 1 for “Z-Boson”
and “Leading Jet” events as a function of the leading jet pT or PT(Z) 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 AW and Tune A, respectively, at the
particle level (i.e. generator level).
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 34
The “TransMAX/MIN” Regions
"TransDIF"
Charged
Particle
Density:
dN/dhd
"TransDIF" Charged
Particle
Density:
dN/dhd
Charged
Particle
Density:
dN/dhd
"TransMAX/MIN"
Charged
Particle
Density:
dN/dhd Charged Particle"TransMAX/MIN"
"TransMAX/MIN"
Charged
Particle
Density:
dN/dhd
"TransDIF"
Density:
dN/dhd
"Drell-Yan
Production"
"Drell-Yan
Production"
"Drell-Yan
Production"
70
M(pair)
110
GeV
70
M(pair)
110
GeV
70
<<<
M(pair)
<<<
110
GeV
"transMAX"
"transMAX"
0.6
0.8
0.8
ATLAS
0.9
0.6
pyDW
JIM
HW
"transMIN"
"transMIN"
0.3
0.4
0.4
ATLAS
HW
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
excluding the lepton-pair
0.0
0.0
00
20
20
"Z-Boson"
0.3
0.0
60
60 0
40
40
80 40
20 80
PT(Z-Boson)
PT(Z-Boson) (GeV/c)
(GeV/c)
Z-Boson Direction
D
High PT Z-Boson Production
TransMAX
- TransMIN
"Transverse"
Charged Density
Density
Charged Particles
Particles (|h|<1.0,
(|h|<1.0,
PT>0.5
GeV/c)
Charged
PT>0.5
GeV/c)
CDF Run
2 Preliminary
excluding the
the lepton-pair
lepton-pair
excluding
data
corrected
pyAW
pyDW
pyAW
JIM
generator level theory
datacorrected
corrected
data
corrected
data
generatorlevel
leveltheory
theory
generator
level
theory
generator
0.9
1.2
1.2
1.6
1.2
1.2
CDFRun
Run222Preliminary
Preliminary
CDF
Run
Preliminary
CDF
"TransDIF" Charged Density
TransMAX - TransMIN
"Transverse"
Charged
"Transverse"
Charged Density
Density
1.2
1.6
1.6
100 80
60100
CDF Run
Run 22 Preliminary
Preliminary
CDF
"Leading
Jet"
data corrected
1.2
0.9
HW
HW
"transMIN"
0.4
0.3
"Leading Jet"
MidPoint R=0.7 |h(jet#1)|<2
Charged Particles (|h|<1.0, PT>0.5 GeV/c) Charged Particles (|h|<1.0, PT>0.5 GeV/c)
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
0.0
0
100
0
120 50
160
50 140 100
100
150
180
150
200
200
200
250
250
Jet #1 Direction
Initial-State Radiation
300
300
350
350
400
400
PT(jet#1)
PT(jet#1) (GeV/c)
(GeV/c)
Outgoing Parton
D
PT(hard)
Initial-State Radiation
“Toward”
Proton
“TransMAX”
"Leading Jet"
MidPoint R=0.7 |h(jet#1)|<2
PY Tune A
PY Tune A
0.8
0.6
PT(jet#1) or PT(Z-Boson) (GeV/c)
Outgoing Parton
"transMAX"
data corrected
generatorlevel
leveltheory
theory
generator
AntiProton
“Toward”
Proton
AntiProton
Underlying Event
“TransMIN”
“TransMAX”
“Away”
“TransMIN”
“Away”
Outgoing Parton
Z-boson
Underlying Event
Final-State
Radiation

particle
density,
dN/dhd,
withwith
pT > p0.5
GeV/c and |h| < 1 for “Z-Boson” and
Data
Dataat
at1.96
1.96TeV
TeVon
onthe
thecharged
density of
charged
particles,
dN/dhd,
T > 0.5 GeV/c and |h| < 1 for “leading
“Leading
Jet”
as aof
function
of PTjet
(Z)por
the leading jet pT for the
“transMIN” regions.
jet” events
as aevents
function
the leading
as“transMAX”,
a function of Pand
T and for Z-Boson events
T(Z) for “TransDIF” =
The
data are corrected
to the particle
level (with
errors
includeto
both
statistical
the that
systematic
“transMAX”
minus “transMIN”
regions.
The data
arethat
corrected
thethe
particle
levelerror
(withand
errors
include
uncertainty)
and
are
compared
with
PYTHIA
Tune
AW
and
Tune
A,
respectively,
at
the
particle
level
(i.e.
both the statistical error and the systematic uncertainty) and are compared with PYTHIA Tune A and HERWIG
generator
level).at the particle level (i.e. generator level).
(without MPI)
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 35
The “TransMAX/MIN” Regions
3.0
3.0
3.0
CDFRun
Run22Preliminary
Preliminary
CDF
datacorrected
corrected
data
generatorlevel
leveltheory
theory
generator
Charged Particles
(|h|<1.0,
GeV/c)
CDF
RunPT>0.5
2 Preliminary
excluding the lepton-pair
data corrected
generator level theory
pyAW
2.0
2.0
"Drell-Yan Production"
"transMAX"
70 <"Drell-Yan
M(pair) < Production"
110 GeV
70 < M(pair) < 110 GeV
1.0
1.0
HW
20
20
1.0 HW
0.0
60
60 0
40
40
D
High PT Z-Boson Production
data
corrected
data
corrected
"Leading
Jet"
generator
level
theory
generator
level
theory
80 40
20 80
10080
60 100
PY Tune A
PY Tune A
"Leading Jet"
"Leading Jet"
MidPoint R=0.7 |h(jet#1)|<2
MidPoint R=0.7 |h(jet#1)|<2
HW
"transMIN"
HW
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
0.0
1000 0 120 5050140
100
160
100
PT(jet#1) or PT(Z-Boson) (GeV/c)
Outgoing Parton
150
180
150
200
200
200
250
250
Jet #1 Direction
Initial-State Radiation
300
300
350
350
400
400
PT(jet#1)(GeV/c)
(GeV/c)
PT(jet#1)
Outgoing Parton
D
PT(hard)
Initial-State Radiation
“Toward”
Proton
“TransMAX”
"transMAX"
1.0
1.0
PT(Z-Boson)
PT(Z-Boson) (GeV/c)
(GeV/c)
Z-Boson Direction
CDF
CDFRun
Run2 2Preliminary
Preliminary
2.0
2.0
"Z-Boson"
"transMIN"
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
excluding the lepton-pair
0.0
0.0
00
2.0
pyAW
"Transverse" PTsum Density (GeV/c)
TransMAX - TransMIN Density (GeV/c)
3.0
3.0
"TransDIF" PTsum Density (GeV/c)
"Transverse"
PTsum Density
TransMAX
- TransMIN
Density (GeV/c)
(GeV/c)
"TransMAX/MIN"
PTsum Density
"TransMAX/MIN"
Charged
"TransDIF"
Charged
PTsum PTsum
Density:Density
dPT/dhd
"TransDIF"
ChargedCharged
PTsum Density:
dPT/dhd
"TransDIF" Charged PTsum Density:
dPT/dhd
AntiProton
“Toward”
Proton
AntiProton
Underlying Event
“TransMIN”
“TransMAX”
“Away”
“TransMIN”
“Away”
Outgoing Parton
Z-boson
Underlying Event
Final-State
Radiation

 Data
Data at
at 1.96
1.96 TeV
TeV on
on the
the charged
charged scalar
scalar PTsum
PTsum density,
density, dPT/dhd,
dPT/dhd, with
with ppTT >> 0.5
0.5 GeV/c
GeV/c and
and |h|
|h| << 11 for
for “Z-Boson”
“leading
and
eventsofasthe
a function
of PpT(Z)
or the leading jet pT for
“transMAX”,
jet” “Leading
events as aJet”
function
leading jet
as athe
function
of PT(Z)and
for “transMIN”
“TransDIF” =
T and for Z-Boson events
regions.
The
data
are
corrected
to
the
particle
level
(with
errors
that
include
both
the
statistical
error
and
the
“transMAX” minus “transMIN” regions. The data are corrected to the particle level (with errors that
include
systematic
uncertainty)
PYTHIAand
Tune
and Tune
A, respectively,
at A
the
particle
level
both the statistical
errorand
andare
thecompared
systematicwith
uncertainty)
areAW
compared
with
PYTHIA Tune
and
HERWIG
(i.e.
generator
(without
MPI)level).
at the particle level (i.e. generator level).
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 36
Charged Particle <pT>
H. Hoeth, MPI@LHC08
"Toward" Average PT Charged
"Transverse" Average PT
1.6
CDF Run 2 Preliminary
CDF Run 2 Preliminary
data corrected
generator level theory
"Toward" <PT> (GeV/c)
"Transverse" Average PT (GeV/c)
2.0
PY Tune A
1.5
1.0
"Leading Jet"
MidPoint R=0.7 |h(jet#1)|<2
HW
data corrected
generator level theory
"Drell-Yan Production"
70 < M(pair) < 110 GeV
pyDW
pyAW
1.2
0.8
ATLAS
JIM
HW
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
excluding the lepton-pair
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.4
0.5
0
50
100
150
200
250
300
350
400
0
20
40
60
PT(jet#1) (GeV/c)
Jet #1 Direction
100
Z-BosonDirection
D
D
“Toward”
“Transverse”
80
PT(Z-Boson) (GeV/c)
“Toward”
“Transverse”
“Transverse”
“Away”
“Transverse”
“Away”
 Data at 1.96 TeV on the charged particle average pT, with pT > 0.5 GeV/c and |h| < 1 for the “toward”
region for “Z-Boson” and the “transverse” region for “Leading Jet” events as a function of the
leading jet pT or PT(Z). 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 AW and Tune A,
respectively, at the particle level (i.e. generator level). The Z-Boson data are also compared with
PYTHIA Tune DW, the ATLAS tune, and HERWIG (without MPI)
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 37
Z-Boson: “Towards”, Transverse”,
& “TransMIN” Charge Density
H. Hoeth, MPI@LHC08
Charged
Particle
Density:
dN/dhd
Charged
Particle
Density:
dN/dhd
"TransMIN"
Charged
Particle
Density:
dN/dhd
"Toward"
Charged
Particle
Density:
dN/dhd
"TransMIN" Charged Particle Density:
dN/dhd
High
PT Z-Boson
Production
Outgoing Parton
datagenerator
correctedlevel
pyAW
generator level theory
"Toward"
0.3
0.3
"Drell-Yan Production"
Production"
"Drell-Yan
70 << M(pair)
M(pair) <
70
< 110
110 GeV
GeV
HW
20
20
0.6
pyDW
data corrected
generator level theory
0.4
0.2
pyAW
Charged
Charged Particles
Particles (|h|<1.0,
(|h|<1.0, PT>0.5
PT>0.5 GeV/c)
GeV/c)
"Z-Boson"
excluding
excluding the
the lepton-pair
lepton-pair
0.0
0.0
00
CDF Run 2 Preliminary
"Transverse
ATLAS
JIM
0.6
0.6
0.0
60
60 0
40
40
PT(Z-Boson)
PT(Z-Boson) (GeV/c)
(GeV/c)
Initial-State Radiation
0.9
0.6
0.8
Charged
Density
"TransMIN"
Charged
Density
CDF Run 2 Preliminary
CDF Run
2 Preliminary
data corrected
"TransMIN" Charged Density
Charged
Density
"Toward"
Charged
Density
0.9
0.9
Initial-State Radiation
CDF Run 2 Preliminary
data corrected
Proton
generator
level theory
pyAW
generator
level
0.6
0.4
"Leading Jet"
"Drell-Yan Production"
"Drell-Yan Production"
70 < M(pair) < 110 GeV
70 < M(pair) < 110 GeV
AntiProtonpyDW
ATLAS
JIM
"Toward"
0.3
0.2
Z-boson
Z-boson
"transMIN"
Charged
Charged Particles
Particles (|h|<1.0,
(|h|<1.0, PT>0.5
PT>0.5 GeV/c)
GeV/c)
pyAW
HW
excluding
excluding the
the lepton-pair
lepton-pair
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
80 40
20 80
100 80
60 100
1000
120
20
140
PT(jet#1) or PT(Z-Boson) (GeV/c)
160
40
180
60
200
100
PT(Z-Boson) (GeV/c)
Z-BosonDirection
Z-Boson Direction
D
D
“Toward”
“Toward”
“Transverse”
80
“TransMAX”
“Transverse”
“TransMIN”
“Away”
“Away”
 Data at 1.96 TeV on the density of charged particles, dN/dhd, with pT > 0.5 GeV/c and |h| < 1 for “ZBoson” events as a function of PT(Z) for the “toward” 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 AW and HERWIG (without MPI) at the particle
level (i.e. generator level).
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 38
Z-Boson: “Towards”, Transverse”,
& “TransMIN” Charge Density
H. Hoeth, MPI@LHC08
1.8
1.2
data
datacorrected
corrected
pyAW
generator
level
generator
level theory
pyDW
1.2
0.8
"Transverse
0.6
0.4
"Toward"
pyAW
HW
20
20
dataATLAS
corrected
generator level theory
0.4
JIM
0.2
Charged
ChargedParticles
Particles(|h|<1.0,
(|h|<1.0,PT>0.5
PT>0.5GeV/c)
GeV/c)
excluding
excludingthe
thelepton-pair
lepton-pair"Z-Boson"
0.0
0.0
00
0.6
Run 2 Preliminary
0.0
60
60 0
40
40
PT(Z-Boson)
PT(Z-Boson) (GeV/c)
(GeV/c)
"TransMIN" PTsum Density (GeV/c)
"Drell-Yan
CDF
"Drell-YanProduction"
Production"
70
70<<M(pair)
M(pair)<<110
110GeV
GeV
Charged PTsum Density (GeV/c)
0.8
CDF
CDF Run
Run 22 Preliminary
Preliminary
"TransMIN" PTsum Density (GeV/c)
Charged PTsum
"Toward"
PTsumDensity
Density(GeV/c)
(GeV/c)
Charged
PTsum
Density:
dPT/dhd
Charged
PTsum
Density:
dPT/dhd
"Toward"
Charged
PTsum
Density:
dPT/dhd
"TransMIN" Charged PTsum Density:
dPT/dhd
"TransMIN"
Charged
PTsum
Density:
dPT/dhd
High
PT Z-Boson
Production
Outgoing Parton
1.2
0.8
Initial-State Radiation
Initial-State Radiation
"Drell-Yan Production"
CDF
CDF Run
Run 22 Preliminary
Preliminary
"Drell-Yan Production"
70 < M(pair) < 110 GeV
70 < M(pair) < 110 GeV
AntiProtonpyDW
data
datacorrected
corrected
0.6
0.8
Proton
"Leading
Jet"
pyAW
generator
level
generator
level theory
JIM
ATLAS "Toward"
0.4
0.4
Z-boson
Z-boson
0.2
"transMIN"
Charged Particles
pyAW (|h|<1.0,
HWPT>0.5 GeV/c)
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
excluding the lepton-pair
excluding the lepton-pair
0.0
0.0
80 40
20 80
100 80
60 100
10000
120
20
20 160
140
PT(jet#1) or PT(Z-Boson) (GeV/c)
40
40
180
60
60
200
100
100
PT(Z-Boson)
PT(Z-Boson) (GeV/c)
(GeV/c)
Z-BosonDirection
Z-Boson Direction
D
D
“Toward”
“Toward”
“Transverse”
80
80
“TransMAX”
“Transverse”
“TransMIN”
“Away”
“Away”
 Data at 1.96 TeV on the charged scalar PTsum density, dPT/dhd, with pT > 0.5 GeV/c and |h| < 1 for
“Z-Boson” events as a function of PT(Z) for the “toward” 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 AW and HERWIG (without MPI) at the particle
level (i.e. generator level).
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 39
Z-Boson: “Towards” Region
"Toward" Charged Particle Density: dN/dhd
"Toward" Charged Particle Density: dN/dhd
CDF Run 2 Preliminary
CDF Run 2 Preliminary
generator level theory
data corrected
generator level theory
1.5
0.6
1.0
2.0
0.9
"Drell-Yan Production"
pyDWT LHC14
70 < M(pair) pyDW
< 110 GeV
ATLAS
JIM
HW Tevatron
pyDWT Tevatron
HW LHC14
DWT
0.3
pyAW
0.5
"Drell-Yan Production"
70 < M(pair) < 110 GeV
HW
Charged
ChargedParticles
Particles(|h|<1.0,
(|h|<1.0,PT>0.5
PT>0.5GeV/c)
GeV/c)
excluding
excludingthe
thelepton-pair
lepton-pair
0.0
0.0
00
2520
50
40
75
60
100
80125
"Toward"Charged
ChargedDensity
Density
"Toward"
"Toward" Charged Density
0.9
2.0
CDF Run 2 Preliminary
CDF Run
2 Preliminary
data corrected
pyDWT
datagenerator
correctedlevel
HW generator level
1.5
"Drell-Yan Production"
LHC14
"Drell-Yan
Production"
70 < M(pair)
< 110 GeV
70 < M(pair) < 110 GeV
LHC14
0.6
1.0
Tevatron
LHC10
0.3
0.5
LHC10
Tevatron
Charged
Charged Particles
Particles (|h|<1.0,
(|h|<1.0, PT>0.5
PT>0.5 GeV/c)
GeV/c)
excluding
excluding the
the lepton-pair
lepton-pair
0.0
0.0
100
150
00
25 20
50
75
40
60 100
PT(Z-Boson)
PT(Z-Boson) (GeV/c)
(GeV/c)
PT(Z-Boson)
PT(Z-Boson) (GeV/c)
(GeV/c)
Z-BosonDirection
Z-BosonDirection
D
D
“Toward”
“Transverse”
80125
HW without MPI
“Toward”
“Transverse”
“Transverse”
“Transverse”
“Away”
“Away”
 Data at 1.96 TeV on the density of charged particles, dN/dhd, with pT > 0.5 GeV/c and |h| < 1 for “ZBoson” events as a function of PT(Z) for the “toward” region. 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 AW and HERWIG (without MPI) at the particle level (i.e. generator
level).
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 40
150
100
Z-Boson: “Towards” Region
"Toward" Average PT Charged
"Toward" Average PT Charged
1.6
1.6
data corrected
generator level theory
CDF Run 2 Preliminary
"Drell-Yan Production"
70 < M(pair) < 110 GeV
pyDW
"Toward" <PT> (GeV/c)
"Toward" <PT> (GeV/c)
CDF Run 2 Preliminary
pyAW
1.2
0.8
ATLAS
JIM
HW
"Drell-Yan Production"
70 < M(pair) < 110 GeV
1.2
DWT
0.8
HW LHC14
HW Tevatron
pyDWT Tevatron
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
excluding the lepton-pair
0.4
pyDWT LHC14
data corrected
generator level theory
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
excluding the lepton-pair
0.4
0
20
40
60
80
100
0
20
PT(Z-Boson) (GeV/c)
40
60
Z-BosonDirection
D
D
“Transverse”
“Transverse”
100
PT(Z-Boson) (GeV/c)
Z-BosonDirection
“Toward”
80
HW (without MPI)
almost no change!
“Toward”
“Transverse”
“Transverse”
“Away”
“Away”
 Data at 1.96 TeV on the average pT of charged particles with pT > 0.5 GeV/c and |h| < 1 for “Z-Boson”
events as a function of PT(Z) for the “toward” region. 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 AW and HERWIG (without MPI) at the particle level (i.e. generator level).
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 41
The “Transverse” Region
“Leading Jet”
Jet #1 Direction
D
“Toward”
“Transverse”
“Transverse”
“Away”
Data - Theory
(GeV) (GeV)
"Transverse"
ETsum Density
5.0
1.6
0.4Density:
density corresponds
"Transverse" ETsum
dET/dhdto
1.67 GeV in the
CDF CDF
Run Run
2 Preliminary
2 Preliminary “transverse”
"Leading
Jet"
region!
data corrected
data corrected
generator
level theory
generator
level theory
4.0
1.2
MidPoint R=0.7 |h(jet#1)|<2
Stable Particles (|h|<1.0, all PT)
HW
3.0
0.8
PY Tune A
2.0
0.4
PY Tune A
1.0
0.0
"Leading Jet"
MidPoint R=0.7 |h(jet#1)|<2
HW
Stable Particles (|h|<1.0, all PT)
0.0
-0.4
00
50
50
100
100
150
150
200
250
300
350
400
PT(jet#1) (GeV/c)

1.96
TeV- on
the scalar
ETscalar
sum density,
with |h| <with
1 for
jet” events
a function
 Data
Showsatthe
Data
Theory
for the
ET sum dET/dhd,
density, dET/dhd,
|h|“leading
< 1 for “leading
jet”asevents
as a
of
the leading
pT forjet
thep“transverse”
region. The data are corrected to the particle level (with errors that
function
of thejet
leading
T for the “transverse” region for PYTHIA Tune A and HERWIG (without MPI).
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).
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 42
The “TransMAX/MIN” Regions
“Leading Jet”
Jet #1 Direction
D
“Toward”
“TransMAX”
“TransMIN”
“Away”
"TransMAX"
Density
(GeV)
"Transverse"
Density
(GeV)
TransMAX ETsum
-ETsum
TransMIN
(GeV)
"TransveMIN"
ETsum
Density
(GeV)
"TransMAX"
"TransMIN"
ETsum
Density:
dET/dhd
"TransMAX/MIN"
ETsum
Density:
dET/dhd
"TransDIF" ETsum
Density:
dET/dhd
6.0
3.0
6.0
5.0
CDF
"Leading Jet"
CDF Run
Run 22 Preliminary
Preliminary
CDF
Run
4.0
4.0
2.0
4.0
3.0
PY Tune A
2.0
2.0
1.0
2.0
HW
data corrected
generator level theory
HW
PY
PYTune
TuneAA
"Leading Jet"
MidPoint R=0.7 |h(jet#1)|<2
"Leading Jet"
"transMIN"
Jet"
MidPoint "Leading
R=0.7 |h(jet#1)|<2
MidPoint
R=0.7 |h(jet#1)|<2
PY Tune
A
Stable Particles (|h|<1.0, all PT)
Stable
Particles
(|h|<1.0,
all PT)
Stable
Particles
(|h|<1.0,
all PT)
HW
1.0
HW
0.0
0.0
0.0
0.0
CDF Run 2 Preliminary
data
MidPoint R=0.7 |h(jet#1)|<2
datacorrected
corrected
data
corrected
"transMAX"
generator
theory
generatorlevel
level
theory
generator
level
theory
Stable
Particles (|h|<1.0, all PT)
000
50
50
50
100
100
100
150
150
150
200
200
200
250
250
250
250
300
300
300
300
350
350
350
350
400
400
400
400
PT(jet#1)
PT(jet#1) (GeV/c)
(GeV/c)
PT(jet#1)
(GeV/c)

 Data
Data at
at 1.96
1.96 TeV
TeV on
on the
the scalar
scalar E
ETTT sum
sum density,
density, dET/dhd,
dET/dhd, with
with |h|
|h| <
< 11 for
for “leading
“leading jet”
jet” events
events as
as aa function
function of
of
of
leading
“transMAX”
region.
corrected
to the
particle
(with
errors
the
leading
jet
ppT pfor
thethe
“transMIN”
region.
TheThe
datadata
are are
corrected
to the
particle
levellevel
(with
errors
thatthat
T for
thethe
leading
jetjet
T for “transDIF” = “transMAX”-”transMIN. The data are corrected to the particle level (with
include
both
the statistical
and the
systematic
and are compared
PYTHIA
A and
errors that
include
both theerror
statistical
error
and the uncertainty)
systematic uncertainty)
and are with
compared
withTune
PYTHIA
HERWIG
MPI)
at the MPI)
particle
levelparticle
(i.e. generator
Tune A and(without
HERWIG
(without
at the
level (i.e.level).
generator level).
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 43
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
D
CDF
CDFRun
Run22Preliminary
Preliminary
60
"Leading Jet"
MidPoint R=0.7 |h(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 |h(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)

atthe
1.96
TeV- on
the leading
invariant
mass for mass
“leading
jet” events
asevents
a function
of the leading
pT
 Data
Shows
Data
Theory
for thejet
leading
jet invariant
for “leading
jet”
as a function
of thejet
leading
for
“transverse” region. The data are corrected to the particle level (with errors that include both the
jet pthe
T for the “transverse” region for PYTHIA Tune A and HERWIG (without MPI).
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).
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 44
Min-Bias at the LHC
 We have learned a lot about “Min-Bias” at the
Tevatron, but we do not know what to expect at
the LHC. This will depend on the Min-Bias Trigger!
 We are making good progress in understanding
and modeling the “underlying event”. However,
we do not yet have a perfect fit to all the features
of the CDF “underlying event” data!
“Minumum Bias” Collisions
Proton
AntiProton
Charged Particle Density: dN/dh
10
Charged Particle Density
 “Min-Bias” is not well defined. What you
see depends on what you trigger on! Every
trigger produces some biases.
pyA
pyDW
pyDWT
ATLAS
Generator Level
14 TeV
8
6
4
2
Charged Particles (all pT)
0
-10
-8
-6
-4
-2
0
2
4
6
8
10
PseudoRapidity h
Outgoing Parton
PT(hard)
 Need to measure “Min-Bias” and the “underlying
event” at the LHC as soon as possible and tune the
Monte-Carlo modles and compare with CDF!
Initial-State Radiation
Proton
AntiProton
Underlying Event
Outgoing Parton
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Underlying Event
Final-State
Radiation
Page 45
The “Underlying Event” in
High PT Jet Production (LHC)
High PT Jet Production
Outgoing Parton
PT(hard)
Initial-State
Radiation
The “Underlying Event” Proton
Underlying Event
Underlying Event
“Underlying event” much
more active at the LHC!
Final-State
Radiation
Outgoing Parton
"Transverse" Charged Particle Density: dN/dhd
"Transverse" Charged Particle Density: dN/dhd
1.0
2.0
RDF Preliminary
LHC
RDF Preliminary
generator level
0.8
0.6
PY Tune AW
HERWIG
0.4
1.96 TeV
0.2
"Leading Jet"
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
"Transverse" Charged Density
"Transverse" Charged Density
Charged particle density
versus PT(jet#1)
AntiProton
generator level
1.5
PY Tune AW
HERWIG
1.0
CDF
0.5
"Leading Jet"
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
0
50
100
150
200
250
300
350
400
450
500
0
250
500
PT(particle jet#1) (GeV/c)
750
1000
1250
1500
1750
2000
2250
2500
PT(particle jet#1) (GeV/c)
 Charged particle density in the “Transverse”  Charged particle density in the “Transverse”
region versus PT(jet#1) at 1.96 TeV for PY
region versus PT(jet#1) at 14 TeV for PY Tune
Tune AW and HERWIG (without MPI).
AW and HERWIG (without MPI).
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 46
Drell-Yan Production (Run 2 vs LHC)
Drell-Yan Production
Proton
<pT(m+m-)> is much
larger at the LHC!
Lepton-Pair Transverse
Momentum
Lepton
AntiProton
Underlying Event
Underlying Event
Shapes of the pT(m+m-)
distribution at the Z-boson mass.
Initial-State
Radiation
Anti-Lepton
Lepton-Pair Transverse Momentum
Drell-Yan PT(m+m-) Distribution
80
0.10
Drell-Yan
Drell-Yan
LHC
60
1/N dN/dPT (1/GeV)
Average Pair PT
generator level
40
Tevatron Run 2
20
0
0.08
PY Tune DW (solid)
HERWIG (dashed)
0.06
70 < M(m-pair) < 110 GeV
|h(m-pair)| < 6
0.04
0.02
PY Tune DW (solid)
HERWIG (dashed)
Z
generator level
Tevatron Run2
LHC
Normalized to 1
0.00
0
100
200
300
400
500
600
700
800
900
1000
0
5
Lepton-Pair Invariant Mass (GeV)
10
15
20
25
30
35
40
PT(m+m-) (GeV/c)
 Average Lepton-Pair transverse momentum  Shape of the Lepton-Pair pT distribution at the
Z-boson mass at the Tevatron and the LHC for
at the Tevatron and the LHC for PYTHIA
PYTHIA Tune DW and HERWIG (without MPI).
Tune DW and HERWIG (without MPI).
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 47
The “Underlying Event” in
Drell-Yan Production
Drell-Yan Production
The “Underlying Event”
Lepton
Proton
HERWIG (without MPI)
is much less active than
PY Tune AW (with MPI)!
Underlying Event
Charged particle density
versus M(pair)
AntiProton
Underlying Event
“Underlying event” much
more active at the LHC!
Initial-State
Radiation
Anti-Lepton
Charged Particle Density: dN/dhd
Charged Particle Density: dN/dhd
1.5
1.0
RDF Preliminary
generator level
PY Tune AW
0.8
0.6
0.4
HERWIG
0.2
Drell-Yan
1.96 TeV
Z
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
(excluding lepton-pair )
Charged Particle Density
Charged Particle Density
RDF Preliminary
generator level
Z
LHC
1.0
PY Tune AW
CDF
0.5
Drell-Yan
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
(excluding lepton-pair )
HERWIG
0.0
0.0
0
50
100
150
200
250
0
50
100
150
200
250
Lepton-Pair Invariant Mass (GeV)
Lepton-Pair Invariant Mass (GeV)
 Charged particle density versus the lepton-  Charged particle density versus the lepton-pair
invariant mass at 14 TeV for PYTHIA Tune AW
pair invariant mass at 1.96 TeV for PYTHIA
and HERWIG (without MPI).
Tune AW and HERWIG (without MPI).
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 48
UE&MB@CMS
UE&MB@CMS
“Minimum-Bias” Collisions
Proton
Proton
High PT Jet Production
Outgoing Parton
PT(hard)
Initial-State
Radiation
Proton
Proton
Underlying Event
Outgoing Parton
 Min-Bias Studies: Charged particle distributions and
correlations. Construct “charged particle jets” and look
at “mini-jet” structure and the onset of the “underlying
event”. (requires only charged tracks)
Underlying Event
Final-State
Radiation
Drell-Yan Production
Lepton
Proton
Proton
Underlying Event
Underlying Event
Study charged
particles
 “Underlying
Event”
Studies: The “transverse region” in
and“leading
muons using
the
CMS
detector charged particle jet
Jet” and “back-to-back”
atproduction
the LHC (as
soon
possible)!
and
theas“central
region” in Drell-Yan
production. (requires charged tracks and muons for DrellYan)
Initial-State
Radiation
Anti-Lepton
Drell-Yan Production
Lepton-Pair
PT(pair)
Proton
Proton
Underlying Event
Underlying Event
Initial-State
Radiation
Final-State
Radiation
 Drell-Yan Studies: Transverse momentum distribution of
the lepton-pair versus the mass of the lepton-pair,
<pT(pair)>, <pT2(pair)>, ds/dpT(pair) (only requires
muons). Event structure for large lepton-pair pT (i.e. mm
+jets, requires muons).
Outgoing Parton
University of California, Berkeley
January 13, 2009
Rick Field – Florida/CDF/CMS
Page 49
Summary
 It is important to produce a lot of plots (corrected to the particle level) so that the theorists
can tune and improve the QCD Monte-Carlo models. If they improve the “transverse”
region they might miss-up the “toward” region etc.. We need to show the whole story!
 We are making good progress in understanding and
modeling the “underlying event”. However, we do not
Proton
yet have a perfect fit to all the features of the CDF
In my RPM talk on Thursday
CDF Run 2 publication.
“underlying
event” data!
Should be out soon!
I will show new results on
<pand
 There are over 128 plots to get “blessed”
then Nchg
T> versus
forlooked
min-bias
and Z-boson production!
published. So far we have only
at average
quantities. We plan to also produce distributions and
flow plots
Outgoing Parton
PT(hard)
Initial-State Radiation
AntiProton
Underlying Event
Outgoing Parton
 I will construct a “CDF-QCD Data for Theory”
WEBsite with the “blessed” plots together with
tables of the data points and errors so that people
can have access to the results .
Final-State
Radiation
CDF-QCD Data for Theory
 Need to measure “Min-Bias” and the “underlying
event” at the LHC as soon as possible and tune the
Monte-Carlo modles and compare with CDF!
University of California, Berkeley
January 13, 2009
Underlying Event
Rick Field – Florida/CDF/CMS
UE&MB@CMS
Page 50