The LHC Physics Environment
Talk 1: What We Have
Learned at the Tevatron
University of Wisconsin, Madison
June 24th – July 2nd, 2009
Rick Field
University of Florida
Outline of Talk
 The old days of “Feynman-Field Phenomenology”.
 Review what we learned about “minbias”, the “underlying event”, and
“event topologies” in Run 1 at CDF.
Outgoing Parton
 Review the CDF Run 2 “underlying
event” studies in high transverse
momentum jet production and in
“Drell-Yan” production.
PT(hard)
Initial-State Radiation
CDF Run 2
Proton
AntiProton
Underlying Event
 Describe the QCD Monte-Carlo models
Outgoing Parton
Underlying Event
Final-State
Radiation
that are used to simulate hadronhadron collisions.
 Examine some extrapolations from
the Tevatron to the LHC.
2009 CTEQ Summer School
June 30, 2009
CMS at the LHC
Rick Field – Florida/CDF/CMS
UE&MB@CMS
Page 1
Toward and Understanding of
Hadron-Hadron Collisions
Feynman-Field Phenomenology1
Feynman
From 7 GeV/c
and
hat!
Field
Outgoing Parton
p0’s
to 600 GeV/c
Jets. The early days of trying to
understand and simulate hadronhadron collisions.
PT(hard)
Initial-State Radiation
Proton
AntiProton
Underlying Event
Caltech 1973
2009 CTEQ Summer School
June 30, 2009
st
Outgoing Parton
Rick Field – Florida/CDF/CMS
Underlying Event
Final-State
Radiation
Page 2
Hadron-Hadron Collisions
FF1 1977
 What happens when two hadrons
collide at high energy?
Hadron
Hadron
Feynman quote from FF1
???
“The model we shall choose is not a popular one,
 Most of the time the hadrons
ooze
so that we will not duplicate too much of the
through each other andwork
fall apart
(i.e.who are similarly analyzing
of others
no hard scattering). The
outgoing
various
models (e.g. constituent interchange
particles continue in roughly
the same
model, multiperipheral
models, etc.). We shall
Parton-Parton Scattering Outgoing Parton
assume
direction as initial proton
andthat the high PT particles arise from
“Soft” constituent
Collision (no large transverse momentum)
direct hard collisions between
antiproton.
quarks in the incoming particles, which
Hadron
Hadron
 Occasionally there will
be a large
fragment
or cascade down
into several hadrons.”
transverse momentum meson.
Question: Where did it come from?
 We assumed it came from quark-quark
elastic scattering, but we did not know
how to calculate it!
Outgoing Parton
high PT meson
“Black-Box Model”
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 3
Quark-Quark Black-Box Model
No gluons!
Quark Distribution Functions
determined from deep-inelastic
lepton-hadron collisions
FF1 1977
Feynman quote from FF1
“Because of the incomplete knowledge of
our functions some things can be predicted
with more certainty than others. Those
experimental results that are not well
predicted can be “used up” to determine
these functions in greater detail to permit
better predictions of further experiments.
Our papers will be a bit long because we
wish to discuss this interplay in detail.”
Quark-Quark Cross-Section
Unknown! Deteremined from
hadron-hadron collisions.
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Quark Fragmentation Functions
determined from e+e- annihilations
Page 4
Quark-Quark Black-Box Model
Predict
particle ratios
FF1 1977
Predict
increase with increasing
CM energy W
When Jim Cronin’s group at the University
of Chicago measured these rations and we
knew we were on the right track!
The “underlying event”
(Beam-Beam Remnants)!
Predict
overall event topology
(FFF1 paper 1977)
7 GeV/c p0’s!
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 5
QCD Approach: Quarks & Gluons
Quark & Gluon Fragmentation
Functions
Q2 dependence predicted from QCD
Parton Distribution Functions
Q2 dependence predicted from
QCD
FFF2 1978
Feynman quote from FFF2
“We investigate whether the present
experimental behavior of mesons with
large transverse momentum in hadron-hadron
collisions is consistent with the theory of
quantum-chromodynamics (QCD) with
asymptotic freedom, at least as the theory
is now partially understood.”
Quark & Gluon Cross-Sections
Calculated from QCD
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 6
High PT Jets
CDF (2006)
Feynman, Field, & Fox (1978)
Predict
large “jet”
cross-section
30 GeV/c!
Feynman quote from FFF
600writing,
GeV/c Jets!
“At the time of this
there is
still no sharp quantitative test of QCD.
An important test will come in connection
with the phenomena of high PT discussed here.”
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 7
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!
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 8
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.
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 9
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
The “hard core” component
contains both “hard” and
“soft” collisions.
+ 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
“Inelastic Non-Diffractive Component”
“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
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 10
Particle Densities
DhD = 4p = 12.6
2p

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 = 1/4p
3/4p = 0.08
0.24
13 GeV/c PTsum
0
-1
h
+1
Divide by 4p
dPTsum/dhd = 1/4p
3/4p 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.
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 11
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 2p.
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).
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 12
CDF Run 1 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.
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 13
CDF Run 1 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!).
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 14
Min-Bias “Associated”
Charged Particle Density
PTmax Direction
Associated Charged
Charged
Particle
Density:
dN/dhd
Associated
"Transverse"
ChargedParticle
ParticleDensity:
Density:dN/dhd
dN/dhd
D
Associated Charged Particle Density: dN/dhd
10.0
Charged Particle Density
py Tune A generator level
“Toward” Region
PTmax > 2.0 GeV/c
PTmax > 5.0 GeV/c
1.0
PTmax > 10.0 GeV/c
“Transverse”
“Transverse”
0.1
Min-Bias
1.96 TeV
PTmax > 0.5 GeV/c
PTmax > 1.0 GeV/c
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
Density
"Transverse"
Charged
Density
Charged Particle
1.6
2.5
1.2
RDF Preliminary
RDF Preliminary
RDF Preliminary
py Tune A generator level
py Tune A generator level
1.0
2.0
1.2
0.8
1.5
Min-Bias
Min-Bias
Min-Bias
14 TeV
1.96 TeV
“Toward”
14 TeV
"Toward"
"Away"
"Toward"
“Transverse”
~ factor of "Away"
2!
“Transverse”
0.8
0.6
1.0
0.4
0.4
0.5
0.2
1.96 TeV
"Transverse"
"Transverse"
“Away”
Charged
ChargedParticles
Particles(|h|<1.0,
(|h|<1.0,PT>0.5
PT>0.5 GeV/c)
GeV/c)
Charged
Particles
(|h|<1.0,
PT>0.5
GeV/c)
0.0
0.0
0
30
60
90
120
150
180
210
240
270
300
330
360
00
2
D (degrees)
54
6
8
10
10
12
15
14
16
20
18
PTmax (GeV/c)
(GeV/c)
PTmax
 Shows 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 at 1.96 TeV with PTmax > 0.5, 1.0, 2.0, 5.0, and 10.0 GeV/c from PYTHIA
Tune A (generator level).
PTmax Direction
D
“Toward”
“Transverse”
“Transverse”
“Away”
 Shows the “associated” charged particle density in the “toward”, “away” and
“transverse” regions as a function of PTmax for charged particles (pT > 0.5
GeV/c, |h| < 1, not including PTmax) for “min-bias” events at 1.96 TeV from
PYTHIA Tune A (generator level).
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 15
25
20
25
“Transverse” Charged Density
PTmax Direction
D
"Transverse" Charged Particle Density: dN/dhd
0.8
“Transverse”
“Transverse”
“Away”
ChgJet#1 Direction
D
“Toward”
“Transverse”
“Transverse”
“Away”
"Transverse" Charged Density
“Toward”
RDF Preliminary
1.96 TeV
py Tune A generator level
0.6
0.6
0.4
Jet#1
ChgJet#1
0.2
PTmax
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
Jet#1 Direction
D
0
5
10
15
20
25
30
PT(jet#1) or PT(chgjet#1) or PTmax (GeV/c)
“Toward”
“Transverse”
“Transverse”
“Away”
 Shows the charged particle density in the “transverse” region for charged particles (pT > 0.5
GeV/c, |h| < 1) at 1.96 TeV as defined by PTmax, PT(chgjet#1), and PT(jet#1) from PYTHIA
Tune A at the particle level (i.e. generator level).
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 16
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!
2p
“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 = 4p/3.
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 17
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.
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 18
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).
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 19
HERWIG 6.4
“Transverse” Density
D
“Toward”
“Transverse”
“Transverse”
“Away”
1.00
CDF Run 1Data
"Transverse" Charged Density
Charged Jet #1
Direction
HERWIG uses a modified leadinglog parton shower-model which
does agrees better with the data!
"Transverse" Charged Particle Density: dN/dhd
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).
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 20
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.
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 21
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).
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 22
MPI, Pile-Up, and Overlap
MPI: Multiple Parton Interactions
Outgoing Parton
PT(hard)
Initial-State Radiation
Proton
AntiProton
Underlying Event
 MPI: Additional 2-to-2 parton-parton
scatterings within a single protonantiproton collision.
Underlying Event
Outgoing Parton
Final-State
Radiation
Proton
Pile-Up
Pile-Up
AntiProton Proton
AntiProton
Primary
Interaction Region Dz
 Pile-Up: More than one proton-antiproton collision in the
beam crossing.
Overlap
 Overlap: An experimental timing issue where a proton-antiproton
collision from the next beam crossing gets included in the protonantiproton collision from the current beam crossing because the next
crossing happened before the event could be read out.
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 23
Tuning PYTHIA:
Multiple Parton Interaction Parameters
Parameter
Default
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.
Determines the energy
Probability
that of
thethe
MPI
produces two gluons
dependence
MPI!
with color connections to the “nearest neighbors.
0.33
PARP(86)
0.66
PARP(89)
PARP(82)
PARP(90)
PARP(67)
1 TeV
1.9
GeV/c
0.16
1.0
Multiple Parton Interaction
Color String
Color String
I will talk more about the
energy dependence of MPI
tomorrow morning!
Determines the reference energy E .
Probability thatAffects
the MPI
theproduces
amount two
of gluons
either as described
by PARP(85)
or as a closed
initial-state
radiation!
gluon loop. The remaining fraction consists of
quark-antiquark pairs.
0
The cut-off PT0 that regulates the 2-to-2
scattering divergence 1/PT4→1/(PT2+PT02)2
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.
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Multiple PartonDetermine
Interactionby comparing
with 630 GeV data!
Color String
Hard-Scattering Cut-Off PT0
5
PYTHIA 6.206
e = 0.25 (Set A))
4
PT0 (GeV/c)
PARP(85)
Description
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
Page 24
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)
2009 CTEQ Summer School
June 30, 2009
Default parameters give
very poor description of
the “underlying event”!
Rick Field – Florida/CDF/CMS
Page 25
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
Not the default!
New PYTHIA default
(less initial-state radiation)
2009 CTEQ Summer School
June 30, 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 26
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)!
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 27
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!
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 28
“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
2p
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 = 4p/3.
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 29
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.
2009 CTEQ Summer School
June 30, 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 30
“transMAX” & “transMIN”
Jet #1 Direction
Z-Boson
Direction
Jet #1 Direction
D
Area = 4p/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 4p/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.
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 31
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”
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 32
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)!
2009 CTEQ Summer School
June 30, 2009
20
Rick Field – Florida/CDF/CMS
Page 33
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).
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 34
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!
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 35
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
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!
(not the default)
Intrinsic KT
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 36
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
0.4
0.4
0.5
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
1.0
Tune D6
5.0
Tune D6T
Intrinsic KT
2009 CTEQ Summer School
June 30, 2009
ATLAS energy dependence!
(PYTHIA default)
Tune B
Tune AW
PARP(85)
1.0
0.33 tunes!
These are 1.0
“old” PYTHIA
6.2
PARP(86)
1.0
0.66
There 1.0
are new 6.420
tunes
by
Tune BW
PARP(89)
1.96 TeV
1.96 TeV
1.0 TeV
Peter Skands (Tune S320, update of S0)
PARP(90)
0.16
0.16
0.16
Peter
Skands
(Tune
N324,
N0CR)
PARP(62)
1.25
1.25
1.0
Hendrik
Hoeth
(Tune0.2P329, “Professor”)
PARP(64)
0.2
1.0
PARP(84)
Rick Field – Florida/CDF/CMS
Page 37
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
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“Transverse”
PT(JIM)= 3.25 GeV/c.
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4.0
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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
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JM325
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1.0
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MidPoint R = 0.7 |h(jet)| < 2
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PTJIM = 3.6 GeV/c,
PT(particle jet#1) (GeV/c)
JMRAD(73) = 1.8
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generator level theory
All Particles (|h|<1.0)
0.0
0
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Radiation
"Transverse" PTsum Density (GeV/c)
1.6
PT(hard)
Proton
100
200
300
400
500
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1.96 TeV
1.2
JM325
PY Tune A
0.8
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HW
0.4
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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)
2009 CTEQ Summer School
June 30, 2009
0
50
Rick Field – Florida/CDF/CMS
100
150
200
250
300
350
400
450
500
PT(particle jet#1) (GeV/c)
Page 38
“Towards”, “Away”, “Transverse”
“Leading Jet”
Jet #1 Direction
D
“Toward”
“Transverse”
“Transverse”
“Away”
ETsum
Density
(GeV)
Charged
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Density
(GeV/c)
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Density
Charged
Particle
Density:
dN/dhd
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PTsum
Density:
dPT/dhd
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Density:
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50 50
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150
150
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200
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200
250
250
250
300
300
300
350
350
350
400
400
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at compared
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level).
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 39
Charged Particle Density
HERWIG + JIMMY
Tune
(PTJIM
= 3.6)
Charged
ParticleParticle
Density:Density:
dN/dhd
"Transverse"
Charged
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Particle
Density:
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"Away"
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Particle
Density:
dN/dhd
H. Hoeth, MPI@LHC08
3
CDF Run 2 Preliminary
data corrected
data corrected
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0.9
2
"Drell-Yan Production"
70 < M(pair) < 110 GeV
0.6
1
20
20
40
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generator level theory
2
40
80
100
0
60
120
0
"Drell-Yan Production"
70 < M(pair) < 110 GeV
80
160
20
140
180
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20
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40
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60
60
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and “Leading Jet” events as a function of the leading jet pT or PT(Z) for the “toward”, “away”, and
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error and the systematic uncertainty) and are compared with PYTHIA Tune AW and Tune A, respectively, at the
particle level (i.e. generator level).
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 40
Charged PTsum Density
12
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Run2 2Preliminary
Preliminary
CDF
"Away"
data
corrected
data
corrected
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generator level theory
1.5
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8
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excluding the lepton-pair
0
20
40
20
40
80
60
100
60
0
120
80
20
160
140
180
PT(Z-Boson)
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100
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Density(GeV/c)
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“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).
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 41
The “TransMAX/MIN” Regions
"TransDIF"
Charged
Particle
Density:
dN/dhd
"TransDIF" Charged
Particle
Density:
dN/dhd
Charged
Particle
Density:
dN/dhd
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Charged
Particle
Density:
dN/dhd Charged Particle"TransMAX/MIN"
"TransMAX/MIN"
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Density:
dN/dhd
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Density:
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Production"
"Drell-Yan
Production"
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M(pair)
110
GeV
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<<<
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GeV
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both the statistical error and the systematic uncertainty) and are compared with PYTHIA Tune A and HERWIG
generator
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(without MPI)
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 42
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)
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70 < M(pair) < 110 GeV
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excluding the lepton-pair
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0.4
0.5
0
50
100
150
200
250
300
350
400
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60
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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)
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 44
Z-Boson: “Towards”, Transverse”,
& “TransMIN” Charge Density
H. Hoeth, MPI@LHC08
Charged
Particle
Density:
dN/dhd
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Particle
Density:
dN/dhd
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Charged
Particle
Density:
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Particle
Density:
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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).
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 45
Z-Boson: “Towards” Region
"Toward" Charged Particle Density: dN/dhd
"Toward" Charged Particle Density: dN/dhd
"Toward" Charged Particle Density: dN/dhd
data corrected
generator level theory
0.3
"Drell-Yan Production"
70 < M(pair) < 110 GeV
HW
0.0
20
40
pyDW LHC
pyDW
ATLAS
0.6
0
"Toward" Charged Density
"Toward" Charged Density
generator level theory
CDF Run 2 Preliminary
JIM
1.2
0.8
pyDW Tevatron
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
excluding the lepton-pair
60
0.0
PT(Z-Boson) (GeV/c)
0
80
25
Z-BosonDirection
1.6
"Drell-Yan Production"
100
50
data corrected
generator level theory
1.2
LHC
“Transverse”
"Drell-Yan Production"
70 < M(pair) < 110 GeV
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
excluding the lepton-pair
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
excluding the lepton-pair
0
75
25
100
50
75
100
LHC
125
150
Z-BosonDirection
D
“Transverse”
“Transverse”
HERWIG (without MPI)
small change!
“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, Tune DW, PYTHIA ATLAS Tune, HERWIG (without MPI), and
HERWIG (with JIMMY MPI) at the particle level (i.e. generator level).
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
150
PT(lepton-pair) (GeV/c)
125
“Toward”
Tevatron
Tevatron
0.4
“Toward”
“Transverse”
≈2.6
≈2.1
pyHW
Tune
DW
LHC
PT(lepton-pair) (GeV/c)
D
py Tune DWT
CDF Run 70
2 Preliminary
< M(pair) < 110 GeV
HW Tevatron 0.8
pyAW
0.4
pyDWT LHC
"Toward" Charged Density
1.6
0.9
Page 47
Z-Boson: “Towards” Region
"Toward" Average PT Charged
"Toward" Average PT Charged
1.6
1.6
data corrected
generator level theory
"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
CDF Run 2 Preliminary
"Drell-Yan Production"
70 < M(pair) < 110 GeV
1.2
0.8
HW LHC
HW Tevatron
pyDW Tevatron
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
excluding the lepton-pair
0.4
pyDWT LHC
data corrected
pyDW LHC
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
Z-BosonDirection
D
D
“Transverse”
100
“Toward”
“Toward”
“Transverse”
80
PT(lepton-pair) (GeV/c)
Tevatron
LHC
“Transverse”
“Transverse”
“Away”
“Away”
 Data at 1.96 TeV on the 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, Tune DW, PYTHIA ATLAS Tune, HERWIG (without MPI), and
HERWIG (with JIMMY MPI) at the particle level (i.e. generator level).
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 48
Drell-Yan Production
Tevatron 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).
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 49
Leading Jet: “Transverse” Region
"Transverse" Charged Particle Density: dN/dhd
"Transverse" Charged Particle Density: dN/dhd
2.0
1.2
"Transverse" Charged Density
"Transverse" Charged Density
data corrected
generator level theory
0.9
0.6
PY Tune A
"Leading Jet"
MidPoint R=0.7 |h(jet#1)|<2
HW
0.3
py Tune DWT
CDF Run 2 Preliminary
CDF Run 2 Preliminary
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
data corrected
generator level theory
1.6
LHC
1.2
py Tune DW
≈2.2
≈1.8
0.8
0.4
"Leading Jet"
MidPoint R=0.7 |h(jet#1)|<2
Tevatron
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
0
50
100
150
200
250
300
350
400
0
50
100
150
PT(jet#1) (GeV/c)
200
350
400
Jet#1 Direction
D
D
“Toward”
“Transverse”
300
PT(jet#1) (GeV/c)
Jet#1 Direction
“Transverse”
250
“Toward”
Tevatron
LHC
“Away”
“Transverse”
“Transverse”
“Away”
 Data at 1.96 TeV on the density of charged particles, dN/dhd, with pT > 0.5 GeV/c and |h| < 1 for “Leading Jet”
events as a function of PT(jet#1) for the “transverse” 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
A, and HERWIG (without MPI) at the particle level (i.e. generator level).
2009 CTEQ Summer School
June 30, 2009
Rick Field – Florida/CDF/CMS
Page 51
The LHC Physics Environment
Talk 2: Extrapolations from the
Tevatron to RHIC and the LHC
University of Wisconsin, Madison
June 24th – July 2nd, 2009
Rick Field
University of Florida
Outline of Talk
 The Pythia MPI energy scaling parameter

PARP(90).
The “underlying event” at STAR.
Extrapolations to RHIC.
Outgoing Parton
 LHC predictions for the “underlying
event” (hard scattering QCD &
Drell-Yan).
PT(hard)
Initial-State Radiation
Proton
CDF Run 2
 “Min-bias” and “pile-up” at the LHC.
 Correlations: charged particle <pT>
Outgoing Parton
versus the charged multiplicity in “minbias” and Drell-Yan.
 Summary & Conclusions.
 Early LHC Thesis Projects.
2009 CTEQ Summer School
June 30, 2009
AntiProton
Underlying Event
CMS at the LHC
Rick Field – Florida/CDF/CMS
Underlying Event
Final-State
Radiation
UE&MB@CMS
Page 52