What We Have Learned About the
Underlying Event From LHC Data
Findings and Surprises!
Rick Field
University of Florida
University of Toronto Physics
August 23, 2010
Outline of Talk
Outgoing Parton
 How well did we do at predicting
the “underlying event” at 900 GeV
and 7 TeV? PYTHIA 6.2 Tune DW.
PT(hard)
Initial-State Radiation
Proton
Proton
Underlying Event
Underlying Event
 New LHC PYTHIA 6.4 Tunes:
ATLAS Tune AMBT1 (ATLASCONF-2010-031) and CMS
Tune Z1!
Hadron Collider Physics Symposium
Toronto August 23, 2010
Outgoing Parton
Rick Field – Florida/CDF/CMS
Final-State
Radiation
UE&MB@CMS
Page 1
CMS UE Analyses
 Uncorrected data on the “transverse”
region as defined by the leading track,
PTmax, and the leading charged particle
jet, PT(chgjet#1) at 900 GeV (pT > 0.5
GeV/c, |h| < 2.0) compared with several
QCD Monte-Carlo models after detector
simulation.
 Uncorrected data on the “transverse”
region as defined by the leading charged
particle jet, PT(chgjet#1) at 7 TeV and 900
GeV (pT > 0.5 GeV/c, |h| < 2.0) compared
with several QCD Monte-Carlo models
after detector simulation.
UE&MB@CMS
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 2
CMS UE Analyses
Traditional Approach
 Uncorrected data on the “transverse”
region as defined by the leading track,
PTmax, and the leading charged particle
jet, PT(chgjet#1) at 900 GeV (pT > 0.5
GeV/c, |h| < 2.0) compared with several
QCD Monte-Carlo models after detector
simulation.
 Uncorrected data on the “transverse”
region as defined by the leading charged
particle jet, PT(chgjet#1) at 7 TeV and 900
GeV (pT > 0.5 GeV/c, |h| < 2.0) compared
with several QCD Monte-Carlo models
after detector simulation.
UE&MB@CMS
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 3
CMS UE Analyses
New Approach
 Uncorrected data on the “transverse”
region as defined by the leading track,
PTmax, and the leading charged particle
jet, PT(chgjet#1) at 900 GeV (pT > 0.5
GeV/c, |h| < 2.0) compared with several
QCD Monte-Carlo models after detector
simulation.
 Uncorrected data on the “transverse”
region as defined by the leading charged
particle jet, PT(chgjet#1) at 7 TeV and 900
GeV (pT > 0.5 GeV/c, |h| < 2.0) compared
with several QCD Monte-Carlo models
after detector simulation.
UE&MB@CMS
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 4
CMS UE Analyses
New Approach
I assure you that we have not lost site of the
ultimate goal of producing corrected data
that the theorists can use to tune and improve
the QCD Monte-Carlo models. Now that these
papers have been released, we are working
full speed on the corrected data!
 Uncorrected data on the “transverse”
region as defined by the leading track,
PTmax, and the leading charged particle
jet, PT(chgjet#1) at 900 GeV (pT > 0.5
GeV/c, |h| < 2.0) compared with several
QCD Monte-Carlo models after detector
simulation.
 Uncorrected data on the “transverse”
region as defined by the leading charged
particle jet, PT(chgjet#1) at 7 TeV and 900
GeV (pT > 0.5 GeV/c, |h| < 2.0) compared
with several QCD Monte-Carlo models
after detector simulation.
UE&MB@CMS
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 5
ATLAS UE Analysis
 Corrected data on the “towards”, “away”,
and “transverse” regions as defined by the
leading track, PTmax, at 7 TeV and 900 GeV
(pT > 0.5 GeV/c, |h| < 2.5) compared with
several QCD Monte-Carlo models at the
generator level.
Traditional Approach
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 6
ATLAS UE Analysis
Please note that I have read the
ATLAS and CMS data points
off these papers with a ruler
so that I can plot the data
and make comparisons!
Please refer to these papers
 Corrected
the “towards”,
(notdata
myonplots)
for the “away”,
and “transverse” regions as defined by the
true data points!
leading track, PTmax, at 7 TeV and 900 GeV
(pT > 0.5 GeV/c, |h| < 2.5) compared with
several QCD Monte-Carlo models at the
generator level.
None of my plots are
Traditional Approach
the original figures
from the papers!
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 7
“Transverse” Charged Particle Density
PT(chgjet#1) Direction
"Transverse" Charged Particle Density: dN/dhdf
"Transverse" Charged Density
0.8
f
RDF Preliminary
Fake Data
pyDW generator level
ChgJet#1
“Toward”
0.6
PTmax
“Transverse”
0.4
“Transverse”
“Away”
0.2
900 GeV
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
PTmax Direction
0
2
4
6
8
10
12
14
16
18
f
PTmax or PT(chgjet#1) (GeV/c)
 Fake data (from MC) at 900 GeV on the
“transverse” charged particle density,
dN/dhdf, as defined by the leading charged
particle (PTmax) and the leading charged
particle jet (chgjet#1) for charged particles
with pT > 0.5 GeV/c and |h| < 2. The fake
data (from PYTHIA Tune DW) are
generated at the particle level (i.e. generator
level) assuming 0.5 M min-bias events at
900 GeV (361,595 events in the plot).
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
“Toward”
“Transverse”
“Transverse”
“Away”
Rick Field
MB&UE@CMS Workshop
CERN, November 6, 2009
Page 8
“Transverse” Charged Particle Density
"Transverse" Charged Particle Density: dN/dhdf
"Transverse" Charged Particle Density: dN/dhdf
RDF Preliminary
Fake Data
pyDW generator level
"Transverse" Charged Density
"Transverse" Charged Density
0.8
ChgJet#1
0.6
PTmax
0.4
0.2
900 GeV
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.8
CMS Preliminary
ChgJet#1
data uncorrected
pyDW + SIM
0.6
PTmax
0.4
0.2
900 GeV
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
0.0
0
2
4
6
8
10
12
14
16
18
0
2
6
8
10
12
14
16
18
PTmax or PT(chgjet#1) (GeV/c)
PTmax or PT(chgjet#1) (GeV/c)
 Fake data (from MC) at 900 GeV on the
“transverse” charged particle density,
dN/dhdf, as defined by the leading charged
particle (PTmax) and the leading charged
particle jet (chgjet#1) for charged particles
with pT > 0.5 GeV/c and |h| < 2. The fake
data (from PYTHIA Tune DW) are
generated at the particle level (i.e. generator
level) assuming 0.5 M min-bias events at
900 GeV (361,595 events in the plot).
Hadron Collider Physics Symposium
Toronto August 23, 2010
4
 CMS preliminary data at 900 GeV on the
“transverse” charged particle density,
dN/dhdf, as defined by the leading charged
particle (PTmax) and the leading charged
particle jet (chgjet#1) for charged particles
with pT > 0.5 GeV/c and |h| < 2. The data are
uncorrected and compared with PYTHIA
Tune DW after detector simulation (216,215
events in the plot).
Rick Field – Florida/CDF/CMS
Page 9
“Transverse” Charged PTsum Density
"Transverse" Charged PTsum Density: dPT/dhdf
"Transverse" Charged PTsum Density: dPT/dhdf
0.8
0.8
ChgJet#1
Fake Data
pyDW generator level
0.6
PTsum Density (GeV/c)
PTsum Density (GeV/c)
RDF Preliminary
PTmax
0.4
0.2
900 GeV
CMS Preliminary
data uncorrected
pyDW + SIM
0.6
ChgJet#1
PTmax
0.4
0.2
900 GeV
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
0.0
0
2
4
6
8
10
12
14
16
18
0
2
4
6
8
10
12
14
16
PTmax or PT(chgjet#1) (GeV/c)
PTmax or PT(chgjet#1) (GeV/c)
 Fake data (from MC) at 900 GeV on the
 CMS preliminary data at 900 GeV on the
“transverse” charged PTsum density,
“transverse” charged PTsum density,
dPT/dhdf, as defined by the leading charged
dPT/dhdf, as defined by the leading charged
particle (PTmax) and the leading charged
particle (PTmax) and the leading charged
particle jet (chgjet#1) for charged particles
particle jet (chgjet#1) for charged particles
with pT > 0.5 GeV/c and |h| < 2. The fake
with pT > 0.5 GeV/c and |h| < 2. The data are
data (from PYTHIA Tune DW) are generated
uncorrected and compared with PYTHIA
at the particle level (i.e. generator level)
Tune DW after detector simulation (216,215
assuming 0.5 M min-bias events at 900 GeV
events in the plot).
(361,595 events in the plot).
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 10
18
PYTHIA Tune CW
"Transverse" Charged PTsum Density: dPT/dhdf
0.8
0.8
CMS Preliminary
CMS Preliminary
ChgJet#1
data uncorrected
pyCW + SIM
0.6
PTsum Density (GeV/c)
"Transverse" Charged Density
"Transverse" Charged Particle Density: dN/dhdf
PTmax
0.4
0.2
900 GeV
data uncorrected
pyCW + SIM
0.6
ChgJet#1
PTmax
0.4
0.2
900 GeV
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
0.0
0
2
4
6
8
10
12
14
0
2
4
6
8
10
12
PTmax or PT(chgjet#1) (GeV/c)
 CMS preliminary data at 900 GeV on the
“transverse” charged particle density,
dN/dhdf, as defined by the leading charged
particle (PTmax) and the leading charged
particle jet (chgjet#1) for charged particles
with pT > 0.5 GeV/c and |h| < 2. The data are
uncorrected and compared with PYTHIA
Tune CW after detector simulation.
 CMS preliminary data at 900 GeV on the
“transverse” charged PTsum density,
dPT/dhdf, as defined by the leading charged
particle (PTmax) and the leading charged
particle jet (chgjet#1) for charged particles
with pT > 0.5 GeV/c and |h| < 2. The data are
uncorrected and compared with PYTHIA
Tune CW after detector simulation.
Tune DW → Tune CW
PARP(82) = 1.9 → 1.8
PARP(90) = 0.25 → 0.30
PARP(85) = 1.0 → 0.9
PARP(86) = 1.0 → 0.95
Hadron Collider Physics Symposium
Toronto August 23, 2010
14
PTmax or PT(chgjet#1) (GeV/c)
Rick Field – Florida/CDF/CMS
Page 11
PYTHIA Tune DW
"Transverse" Charged Particle Density: dN/dhdf
1.2
PT(chgjet#1) Direction
Charged Particle Density
CMS Preliminary
f
7 TeV
data uncorrected
pyDW + SIM
0.8
“Toward”
“Transverse”
900 GeV
“Transverse”
0.4
“Away”
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
0
5
10
15
20
25
30
35
40
45
50
PT(chgjet#1) GeV/c
 CMS preliminary data at 900 GeV and 7 TeV
on the “transverse” charged particle density,
dN/dhdf, as defined by the leading charged
particle jet (chgjet#1) for charged particles with
pT > 0.5 GeV/c and |h| < 2. The data are
uncorrected and compared with PYTHIA Tune
DW after detector simulation.
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 12
PYTHIA Tune DW
PTmax Direction
f
“Toward”
“Transverse”
“Transverse”
“Away”
"Transverse" Charged Density
"Transverse" Charged Particle Density: dN/dhdf
1.2
RDF Preliminary
7 TeV
ATLAS corrected data
Tune DW generator level
0.8
900 GeV
0.4
Charged Particles (|h|<2.5, PT>0.5 GeV/c)
0.0
0
2
4
6
8
10
12
14
16
18
20
PTmax (GeV/c)
 ATLAS preliminary data at 900 GeV and 7 TeV
on the “transverse” charged particle density,
dN/dhdf, as defined by the leading charged
particle (PTmax) for charged particles with pT >
0.5 GeV/c and |h| < 2.5. The data are corrected
and compared with PYTHIA Tune DW at the
generator level.
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 13
PYTHIA Tune DW
"Transverse" Charged Particle Density: dN/dhdf
"Transverse" Charged Particle Density: dN/dhdf
Charged Particle Density
CMS Preliminary
"Transverse" Charged Density
1.2
7 TeV
data uncorrected
pyDW + SIM
0.8
CMS
900 GeV
0.4
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
1.2
RDF Preliminary
7 TeV
ATLAS corrected data
Tune DW generator level
0.8
ATLAS
900 GeV
0.4
Charged Particles (|h|<2.5, PT>0.5 GeV/c)
0.0
0.0
0
5
10
15
20
25
30
35
40
45
50
0
2
4
6
8
10
12
14
16
18
20
PTmax (GeV/c)
PT(chgjet#1) GeV/c
 CMS preliminary data at 900 GeV and 7 TeV  ATLAS preliminary data at 900 GeV and 7 TeV
on the “transverse” charged particle density,
on the “transverse” charged particle density,
dN/dhdf, as defined by the leading charged
dN/dhdf, as defined by the leading charged
particle jet (chgjet#1) for charged particles with particle (PTmax) for charged particles with pT >
pT > 0.5 GeV/c and |h| < 2. The data are
0.5 GeV/c and |h| < 2.5. The data are corrected
uncorrected and compared with PYTHIA Tune and compared with PYTHIA Tune DW at the
DW after detector simulation.
generator level.
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 14
PYTHIA Tune DW
"Transverse" Charged PTsum Density: dPT/dhdf
1.5
CMS Preliminary
RDF Preliminary
7 TeV
data uncorrected
pyDW + SIM
1.2
PTsum Density (GeV/c)
Charged PTsum Density (GeV/c)
"Transverse" Charged PTsum Density: dPT/dhdf
1.6
CMS
0.8
900 GeV
0.4
7 TeV
ATLAS corrected data
Tune DW generator level
1.0
ATLAS
900 GeV
0.5
Charged Particles (|h|<2.5, PT>0.5 GeV/c)
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
0.0
0
5
10
15
20
25
30
35
40
45
50
0
2
4
6
8
10
12
14
16
18
PTmax (GeV/c)
PT(chgjet#1) (GeV/c)
 CMS preliminary data at 900 GeV and 7 TeV  ATLAS preliminary data at 900 GeV and 7
on the “transverse” charged PTsum density,
TeV on the “transverse” charged PTsum
dPT/dhdf, as defined by the leading charged
density, dPT/dhdf, as defined by the
particle jet (chgjet#1) for charged particles
leading charged particle (PTmax) for
with pT > 0.5 GeV/c and |h| < 2. The data are
charged particles with pT > 0.5 GeV/c and
uncorrected and compared with PYTHIA
|h| < 2.5. The data are corrected and
Tune DW after detector simulation.
compared with PYTHIA Tune DW at the
generator level.
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 15
20
PYTHIA Tune DW
"Transverse" Charged Particle Density: dN/dhdf
1.2
PT(jet#1) Direction
“Toward”
“Transverse”
“Transverse”
“Away”
CDF Published
Charged Particle Density
f
1.96 TeV
data corrected
pyDW generator level
0.8
0.4
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
0
50
100
150
200
250
300
350
PT(jet#1) GeV/c
 CDF published data at 1.96 TeV on the
“transverse” charged particle density,
dN/dhdf, as defined by the leading
calorimeter jet (jet#1) for charged particles
with pT > 0.5 GeV/c and |h| < 1.0. The data
are corrected and compared with PYTHIA
Tune DW at the generator level.
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 16
400
PYTHIA Tune DW
"Transverse" Charged Particle Density: dN/dhdf
"Transverse" Charged Particle Density: dN/dhdf
1.2
1.2
CDF Published
7 TeV
data uncorrected
pyDW + SIM
Charged Particle Density
Charged Particle Density
CMS Preliminary
0.8
CMS
900 GeV
0.4
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
1.96 TeV
data corrected
pyDW generator level
0.8
CDF
0.4
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
0.0
0
5
10
15
20
25
30
35
40
45
50
0
50
100
150
200
250
300
350
PT(jet#1) GeV/c
PT(chgjet#1) GeV/c
 CMS preliminary data at 900 GeV and 7 TeV  CDF published data at 1.96 TeV on the
on the “transverse” charged particle density,
“transverse” charged particle density,
dN/dhdf, as defined by the leading charged
dN/dhdf, as defined by the leading
particle jet (chgjet#1) for charged particles
calorimeter jet (jet#1) for charged particles
with pT > 0.5 GeV/c and |h| < 2. The data are
with pT > 0.5 GeV/c and |h| < 1.0. The data
uncorrected and compared with PYTHIA
are corrected and compared with PYTHIA
Tune DW after detector simulation.
Tune DW at the generator level.
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 17
400
PYTHIA Tune DW
"Transverse" Charged Particle Density: dN/dhdf
"Transverse" Charged Particle Density: dN/dhdf
1.2
1.2
RDF Preliminary
7 TeV
data uncorrected
pyDW + SIM
Charged Particle Density
Charged Particle Density
CMS Preliminary
0.8
CMS
900 GeV
0.4
CMS 7 TeV
Tune DW
CDF 1.96 TeV
0.8
CMS 900 GeV
0.4
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
Charged Particles (PT>0.5 GeV/c)
0.0
0.0
0
5
10
15
20
25
30
35
40
45
50
0
10
20
30
40
50
60
70
80
90
100
PT(chgjet#1 or jet#1) GeV/c
PT(chgjet#1) GeV/c
 CMS preliminary data at 900 GeV and 7 TeV  CDF published data at 1.96 TeV on the
on the “transverse” charged particle density,
“transverse” charged particle density,
dN/dhdf, as defined by the leading charged
dN/dhdf, as defined by the leading
particle jet (chgjet#1) for charged particles
calorimeter jet (jet#1) for charged particles
with pT > 0.5 GeV/c and |h| < 2. The data are
with pT > 0.5 GeV/c and |h| < 1.0. The data
uncorrected and compared with PYTHIA
are corrected and compared with PYTHIA
Tune DW after detector simulation.
Tune DW at the generator level.
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 18
“Transverse” Charge Density
"Transverse" Charged Particle Density: dN/dhdf
Rick Field
MB&UE@CMS Workshop
CERN, November 6, 2009
"Transverse" Charged Density
1.2
RDF Preliminary
py Tune DW generator level
7 TeV
0.8
factor of 2!
900 GeV
0.4
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
0
2
4
6
8
10
12
14
16
18
20
PTmax (GeV/c)
PTmax Direction
f
LHC
900 GeV
“Toward”
“Transverse”
PTmax Direction
900 GeV → 7 TeV
(UE increase ~ factor of 2)
“Transverse”
“Away”
~0.4 → ~0.8
f
“Toward”
LHC
7 TeV
“Transverse”
“Transverse”
“Away”
 Shows the charged particle density in the “transverse” region for charged particles (pT > 0.5
GeV/c, |h| < 2) at 900 GeV and 7 TeV as defined by PTmax from PYTHIA Tune DW and at the
particle level (i.e. generator level).
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 19
PYTHIA Tune DW
"Transverse" Charged Particle Density: dN/dhdf
"Transverse" Charged Particle Density: dN/dhdf
3.0
3.0
RDF Preliminary
data uncorrected
pyDW + SIM
Ratio: 7 TeV/900 GeV
Ratio: 7 TeV/900 GeV
CMS Preliminary
2.0
CMS
1.0
7 TeV / 900 GeV
ATLAS corrected data
pyDW generator level
2.0
ATLAS
1.0
7 TeV / 900 GeV
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
Charged Particles (|h|<2.5, PT>0.5 GeV/c)
0.0
0.0
0
2
4
6
8
10
12
14
16
18
0
1
2
3
4
5
6
7
8
9
10
11
PTmax (GeV/c)
PT(chgjet#1) (GeV/c)
 CMS preliminary data at 900 GeV and 7 TeV  ATLAS preliminary data at 900 GeV and 7
on the “transverse” charged particle density,
TeV on the “transverse” charged particle
dN/dhdf, as defined by the leading charged
density, dN/dhdf, as defined by the leading
particle jet (chgjet#1) for charged particles
charged particle (PTmax) for charged
with pT > 0.5 GeV/c and |h| < 2. The data are
particles with pT > 0.5 GeV/c and |h| < 2.5.
uncorrected and compared with PYTHIA
The data are corrected and compared with
Tune DW after detector simulation.
PYTHIA Tune DW at the generator level.
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 20
12
PYTHIA Tune DW
"Transverse" Charged PTsum Density: dPT/dhdf
"Transverse" Charged PTsum Density: dPT/dhdf
4.0
3.0
CMS Preliminary
RDF Preliminary
data uncorrected
pyDW + SIM
ATLAS corrected data
pyDW generator level
Ratio: 7 TeV/900 GeV
Ratio: 7 TeV/900 GeV
4.0
2.0
CMS
1.0
3.0
2.0
ATLAS
1.0
7 TeV / 900 GeV
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
7 TeV / 900 GeV
Charged Particles (|h|<2.5, PT>0.5 GeV/c)
0.0
0.0
0
2
4
6
8
10
12
14
16
18
0
1
2
3
4
5
6
7
8
9
10
11
PTmax (GeV/c)
PT(chgjet#1) (GeV/c)
 CMS preliminary data at 900 GeV and 7 TeV  ATLAS preliminary data at 900 GeV and 7
on the “transverse” charged PTsum density,
TeV on the “transverse” charged PTsum
dPT/dhdf, as defined by the leading charged
density, dPT/dhdf, as defined by the
particle jet (chgjet#1) for charged particles
leading charged particle (PTmax) for
with pT > 0.5 GeV/c and |h| < 2. The data are
charged particles with pT > 0.5 GeV/c and
uncorrected and compared with PYTHIA
|h| < 2.5. The data are corrected and
Tune DW after detector simulation.
compared with PYTHIA Tune DW at the
generator level.
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 21
12
“Transverse” Energy Dependence
"Transverse" Charged Particle Density: dN/dhdf
"Transverse" Charged Particle Density: dN/dhdf
3.0
3.0
ATLAS corrected data
generator level theory
D6T
data uncorrected
theory + SIM
Ratio: 7 TeV/900 GeV
Ratio: 7 TeV/900 GeV
RDF Preliminary
DW
CMS Preliminary
2.0
1.0
CW
7 TeV / 900 GeV
CMS
2.0
Tune DW
1.0
ATLAS MC08
Tune CW
ATLAS
7 TeV / 900 GeV
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
Charged Particles (|h|<2.5, PT>0.5 GeV/c)
0.0
0.0
0
2
4
6
8
10
12
14
16
18
0
1
PT(chgjet#1) (GeV/c)
2
3
4
5
6
7
8
9
10
11
PTmax (GeV/c)
 CMS preliminary data at 900 GeV and 7 TeV  ATLAS preliminary data at 900 GeV and 7
on the “transverse” charged particle density,
TeV on the “transverse” charged particle
dN/dhdf, as defined by the leading charged
density, dN/dhdf, as defined by the leading
particle jet (chgjet#1) for charged particles
charged particle (PTmax) for charged
with pT > 0.5 GeV/c and |h| < 2. The data are
particles with pT > 0.5 GeV/c and |h| < 2.5.
uncorrected and compared with PYTHIA
The data are corrected and compared with
Tune DW, Tune CW, and Tune D6T after
PYTHIA Tune DW, Tune CW, and ATLAS
detector simulation.
MC08 at the generator level.
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 22
12
“Transverse” Energy Dependence
PARP(90) = 0.16
"Transverse" Charged Particle Density: dN/dhdf
"Transverse" Charged Particle Density: dN/dhdf
3.0
3.0
D6T
data uncorrected
theory + SIM
Ratio: 7 TeV/900 GeV
Ratio: 7 TeV/900 GeV
RDF Preliminary
DW
CMS Preliminary
2.0
1.0
CW
7 TeV / 900 GeV
CMS
ATLAS corrected data
generator level theory
PARP(90) = 0.25
2.0
Tune DW
1.0
ATLAS MC08
Tune CW
PARP(90) = 0.30
ATLAS
7 TeV / 900 GeV
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
Charged Particles (|h|<2.5, PT>0.5 GeV/c)
0.0
0.0
0
2
4
6
8
10
12
14
16
18
0
1
PT(chgjet#1) (GeV/c)
2
3
4
5
6
7
8
9
10
11
PTmax (GeV/c)
 CMS preliminary data at 900 GeV and 7 TeV  ATLAS preliminary data at 900 GeV and 7
on the “transverse” charged particle density,
TeV on the “transverse” charged particle
dN/dhdf, as defined by the leading charged
density, dN/dhdf, as defined by the leading
particle jet (chgjet#1) for charged particles
charged particle (PTmax) for charged
with pT > 0.5 GeV/c and |h| < 2. The data are
particles with pT > 0.5 GeV/c and |h| < 2.5.
uncorrected and compared with PYTHIA
The data are corrected and compared with
Tune DW, Tune CW, and Tune D6T after
PYTHIA Tune DW, Tune CW, and ATLAS
detector simulation.
MC08 at the generator level.
PT0(E)=PT0(E/E0)e e = PARP(90) PT0 = PARP(82)
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 23
12
“Transverse” Multiplicity Distribution
"Transverse" Charged Particle Multiplicity
Same hard scale at
two different centerof-mass energies!
1.0E+00
PT(chgjet#1) > 3 GeV/c
1.0E-01
CMS Preliminary
data uncorrected
pyDW + SIM
Probability
1.0E-02
CMS
1.0E-03
7 TeV
900 GeV
1.0E-04
1.0E-05
Normalized to 1
1.0E-06
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
1.0E-07
0
5
10
15
20
25
30
35
40
Number of Charged Particles
 CMS uncorrected data at 900 GeV and 7 TeV on the charged particle multiplicity distribution
in the “transverse” region for charged particles (pT > 0.5 GeV/c, |h| < 2) as defined by the
leading charged particle jet, chgjet#1, with PT(chgjet#1) > 3 GeV/c compared with PYTHIA
Tune DW at the detector level (i.e. Theory + SIM).
Shows the growth of the
“underlying event” as the center-of-mass energy increases.
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 24
“Transverse” Multiplicity Distribution
"Transverse" Charged Particle Multiplicity
"Transverse" Charged Particle Multiplicity
1.0E+00
1.0E+00
PT(chgjet#1) > 3 GeV/c
1.0E-01
1.0E-01
data uncorrected
pyD6T + SIM
1.0E-02
1.0E-03
7 TeV
900 GeV
1.0E-04
CMS Preliminary
data uncorrected
pyCW + SIM
1.0E-02
Tune D6T
Probability
Probability
PT(chgjet#1) > 3 GeV/c
CMS Preliminary
Tune CW
1.0E-03
7 TeV
900 GeV
1.0E-04
1.0E-05
1.0E-05
Normalized to 1
Normalized to 1
1.0E-06
1.0E-06
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
1.0E-07
1.0E-07
0
5
10
15
20
25
30
35
0
40
5
10
15
20
25
30
35
Number of Charged Particles
Number of Charged Particles
"Transverse" Charged Particle Multiplicity
1.0E+00
PT(chgjet#1) > 3 GeV/c
1.0E-01
CMS Preliminary
data uncorrected
pyDW + SIM
1.0E-02
Probability
 CMS uncorrected data at 900 GeV and 7 TeV
on the charged particle multiplicity
distribution in the “transverse” region for
charged particles (pT > 0.5 GeV/c, |h| < 2) as
defined by the leading charged particle jet,
chgjet#1, with PT(chgjet#1) > 3 GeV/c
compared with PYTHIA Tune D6T, Tune
DW, and Tune CW at the detector level (i.e.
Theory + SIM).
Tune DW
1.0E-03
7 TeV
900 GeV
1.0E-04
1.0E-05
Normalized to 1
1.0E-06
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
1.0E-07
0
5
10
15
20
25
30
35
Number of Charged Particles
Hadron Collider Physics Symposium
Toronto August 23, 2010
40
Rick Field – Florida/CDF/CMS
Page 25
40
“Transverse” PTsum Distribution
"Transverse" Charged PTsum Distribution
"Transverse" Charged PTsum Distribution
1.0E+00
CMS Preliminary
data uncorrected
pyD6T+ SIM
1.0E-01
7 TeV
1.0E-03
Probability
PT(chgjet#1) > 3 GeV/c
1.0E-02
Tune D6T
900 GeV
1.0E-04
1.0E-05
CMS Preliminary
data uncorrected
pyCW + SIM
1.0E-01
PT(chgjet#1) > 3 GeV/c
1.0E-02
7 TeV
1.0E-03
1.0E-04
1.0E-05
Normalized to 1
Tune CW
900 GeV
Normalized to 1
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
1.0E-06
1.0E-06
0
5
10
15
20
25
30
35
40
45
0
50
5
10
15
 CMS uncorrected data at 900 GeV and
7 TeV on the charged scalar PTsum
distribution in the “transverse” region
for charged particles (pT > 0.5 GeV/c,
|h| < 2) as defined by the leading
charged particle jet, chgjet#1, with
PT(chgjet#1) > 3 GeV/c compared with
PYTHIA Tune D6T, Tune DW, and
Tune CW at the detector level (i.e.
Theory + SIM).
Hadron Collider Physics Symposium
Toronto August 23, 2010
20
25
30
35
40
45
50
PTsum (GeV/c)
PTsum (GeV/c)
"Transverse" Charged PTsum Distribution
1.0E+00
CMS Preliminary
data uncorrected
pyDW + SIM
1.0E-01
Probability
Probability
1.0E+00
PT(chgjet#1) > 3 GeV/c
1.0E-02
7 TeV
1.0E-03
Tune DW
900 GeV
1.0E-04
1.0E-05
Normalized to 1
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
1.0E-06
0
Rick Field – Florida/CDF/CMS
5
10
15
20
25
30
35
40
45
PTsum (GeV/c)
Page 26
50
“Transverse” PT Distribution
"Transverse" Charged PT Distribution
"Transverse" Charged PT Distribution
1.0E+01
1.0E+01
CMS Preliminary
1.0E-01
PT(chgjet#1) > 3 GeV/c
1.0E-02
Tune D6T
900 GeV
1.0E-03
7 TeV
1.0E-04
Normalized to <Nchg>
1.0E-05
CMS Preliminary
1.0E+00
data uncorrected
pyD6T + SIM
dNchg/dPT (1/GeV/c)
dNchg/dPT (1/GeV/c)
1.0E+00
data uncorrected
pyCW + SIM
1.0E-01
PT(chgjet#1) > 3 GeV/c
1.0E-02
Tune CW
900 GeV
1.0E-03
7 TeV
1.0E-04
Normalized to <Nchg>
1.0E-05
Charged Particles (|h|<2.0)
Charged Particles (|h|<2.0)
1.0E-06
1.0E-06
0
2
4
6
8
10
12
14
0
2
4
PT (GeV/c)
6
8
10
12
PT (GeV/c)
"Transverse" Charged PT Distribution
1.0E+01
CMS Preliminary
1.0E+00
dNchg/dPT (1/GeV/c)
 CMS uncorrected data at 900 GeV and 7
TeV on the charged particle PT distribution
in the “transverse” region for charged
particles (|h| < 2) as defined by the leading
charged particle jet, chgjet#1, with
PT(chgjet#1) > 3 GeV/c compared with
PYTHIA Tune D6T, Tune DW, and Tune CW
at the detector level (i.e. Theory + SIM).
data uncorrected
pyDW + SIM
1.0E-01
PT(chgjet#1) > 3 GeV/c
1.0E-02
Tune DW
900 GeV
1.0E-03
7 TeV
1.0E-04
Normalized to <Nchg>
1.0E-05
Charged Particles (|h|<2.0)
1.0E-06
0
2
4
6
8
10
12
PT (GeV/c)
Hadron Collider Physics Symposium
Toronto August 23, 2010
14
Rick Field – Florida/CDF/CMS
Page 27
14
“Transverse” Multiplicity Distribution
Same center-of-mass
energy at two different
hard scales!
"Transverse" Charged Particle Multiplicity
1.0E+00
7 TeV
CMS Preliminary
1.0E-01
data uncorrected
pyDW + SIM
Probability
1.0E-02
PT(chgjet#1) > 20 GeV/c
1.0E-03
1.0E-04
PT(chgjet#1) > 3 GeV/c
1.0E-05
CMS
Normalized to 1
1.0E-06
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
1.0E-07
0
5
10
15
20
25
30
35
40
Number of Charged Particles
 CMS uncorrected data at 7 TeV on the charged particle multiplicity distribution in the
“transverse” region for charged particles (pT > 0.5 GeV/c, |h| < 2) as defined by the leading
charged particle jet, chgjet#1, with PT(chgjet#1) > 3 GeV/c and PT(chgjet#1) > 20 GeV/c
compared with PYTHIA Tune DW at the detector level (i.e. Theory + SIM).
Shows the growth of the
“underlying event” as the hard scale increases.
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 28
“Transverse” Multiplicity Distribution
"Transverse" Charged Particle Multiplicity
"Transverse" Charged Particle Multiplicity
1.0E+00
1.0E+00
7 TeV
1.0E-01
Probability
Tune D6T
1.0E-04
data uncorrected
py8 + SIM
1.0E-02
PT(chgjet#1) > 20 GeV/c
1.0E-03
PT(chgjet#1) > 3 GeV/c
1.0E-05
PT(chgjet#1) > 20 GeV/c
1.0E-03
Tune P8
1.0E-04
PT(chgjet#1) > 3 GeV/c
1.0E-05
Normalized to 1
Normalized to 1
1.0E-06
1.0E-06
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
1.0E-07
1.0E-07
0
5
10
15
20
25
30
35
40
0
5
10
Number of Charged Particles
15
20
25
30
35
40
Number of Charged Particles
"Transverse" Charged Particle Multiplicity
"Transverse" Charged Particle Multiplicity
1.0E+00
1.0E+00
7 TeV
7 TeV
CMS Preliminary
1.0E-01
data uncorrected
pyDW + SIM
1.0E-02
Probability
PT(chgjet#1) > 20 GeV/c
1.0E-03
CMS Preliminary
1.0E-01
data uncorrected
pyCW + SIM
1.0E-02
Probability
CMS Preliminary
1.0E-01
data uncorrected
pyD6T + SIM
1.0E-02
Probability
7 TeV
CMS Preliminary
Tune CW
1.0E-04
PT(chgjet#1) > 3 GeV/c
PT(chgjet#1) > 20 GeV/c
1.0E-03
Tune DW
1.0E-04
PT(chgjet#1) > 3 GeV/c
1.0E-05
1.0E-05
Normalized to 1
Normalized to 1
1.0E-06
1.0E-06
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
1.0E-07
1.0E-07
0
5
10
15
20
25
30
35
40
0
10
15
20
25
30
35
Number of Charged Particles
Number of Charged Particles
Hadron Collider Physics Symposium
Toronto August 23, 2010
5
Rick Field – Florida/CDF/CMS
Page 29
40
“Transverse” PTsum Distribution
"Transverse" Charged PTsum Distribution
"Transverse" Charged PTsum Distribution
1.0E+00
1.0E+00
CMS Preliminary
7 TeV
1.0E-01
data uncorrected
pyD6T + SIM
1.0E-01
1.0E-02
PT(chgjet#1) > 20 GeV/c
1.0E-02
Probability
Probability
7 TeV
Tune D6T
1.0E-03
PT(chgjet#1) > 3 GeV/c
1.0E-04
data uncorrected
py8 + SIM
PT(chgjet#1) > 20 GeV/c
Tune P8
1.0E-03
PT(chgjet#1) > 3 GeV/c
1.0E-04
Normalized to 1
Normalized to 1
1.0E-05
1.0E-05
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
1.0E-06
1.0E-06
0
5
10
15
20
25
30
35
40
45
50
0
5
10
15
PTsum (GeV/c)
20
25
30
35
40
45
50
PTsum (GeV/c)
"Transverse" Charged PTsum Distribution
"Transverse" Charged PTsum Distribution
1.0E+00
1.0E+00
CMS Preliminary
7 TeV
1.0E-02
data uncorrected
pyDW + SIM
1.0E-01
Probability
PT(chgjet#1) > 20 GeV/c
Tune CW
1.0E-03
CMS Preliminary
7 TeV
data uncorrected
pyCW + SIM
1.0E-01
Probability
CMS Preliminary
PT(chgjet#1) > 3 GeV/c
1.0E-04
1.0E-02
PT(chgjet#1) > 20 GeV/c
Tune DW
1.0E-03
PT(chgjet#1) > 3 GeV/c
1.0E-04
Normalized to 1
Normalized to 1
1.0E-05
1.0E-05
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
1.0E-06
1.0E-06
0
5
10
15
20
25
30
35
40
45
50
0
PTsum (GeV/c)
Hadron Collider Physics Symposium
Toronto August 23, 2010
5
10
15
20
25
30
35
40
45
PTsum (GeV/c)
Rick Field – Florida/CDF/CMS
Page 30
50
“Transverse” PT Distribution
"Transverse" Charged PT Distribution
1.0E+01
data uncorrected
pyD6T + SIM
1.0E-01
PT(chgjet#1) > 20 GeV/c
1.0E-02
Tune D6T
1.0E-03
PT(chgjet#1) > 3 GeV/c
1.0E-04
Normalized to <Nchg>
1.0E-05
data uncorrected
py8 + SIM
1.0E-01
PT(chgjet#1) > 20 GeV/c
1.0E-02
Tune P8
1.0E-03
PT(chgjet#1) > 3 GeV/c
1.0E-04
Normalized to <Nchg>
1.0E-05
Charged Particles (|h|<2.0)
Charged Particles (|h|<2.0)
1.0E-06
1.0E-06
0
2
4
6
8
10
12
14
0
2
4
6
PT (GeV/c)
8
10
12
14
PT (GeV/c)
"Transverse" Charged PT Distribution
"Transverse" Charged PT Distribution
1.0E+01
1.0E+01
CMS Preliminary
7 TeV
1.0E+00
1.0E-01
PT(chgjet#1) > 20 GeV/c
1.0E-02
Tune CW
1.0E-03
PT(chgjet#1) > 3 GeV/c
1.0E-04
Normalized to <Nchg>
1.0E-05
CMS Preliminary
7 TeV
1.0E+00
data uncorrected
pyCW + SIM
dNchg/dPT (1/GeV/c)
dNchg/dPT (1/GeV/c)
CMS Preliminary
7 TeV
1.0E+00
dNchg/dPT (1/GeV/c)
dNchg/dPT (1/GeV/c)
1.0E+01
CMS Preliminary
7 TeV
1.0E+00
"Transverse" Charged PT Distribution
data uncorrected
pyDW + SIM
1.0E-01
PT(chgjet#1) > 20 GeV/c
1.0E-02
Tune DW
1.0E-03
PT(chgjet#1) > 3 GeV/c
1.0E-04
Normalized to <Nchg>
1.0E-05
Charged Particles (|h|<2.0)
Charged Particles (|h|<2.0)
1.0E-06
1.0E-06
0
2
4
6
8
10
12
14
0
PT (GeV/c)
Hadron Collider Physics Symposium
Toronto August 23, 2010
2
4
6
8
10
12
PT (GeV/c)
Rick Field – Florida/CDF/CMS
Page 31
14
PYTHIA Tune DW
How well did we do at predicting the “underlying event” at 900 GeV and 7 TeV?
"Transverse" Charged Particle Density: dN/dhdf
1.2
CMS Preliminary
CMS Preliminary
ChgJet#1
data uncorrected
pyDW + SIM
0.6
Charged Particle Density
"Transverse" Charged Density
"Transverse" Charged Particle Density: dN/dhdf
0.8
PTmax
0.4
0.2
900 GeV
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
7 TeV
data uncorrected
pyDW + SIM
0.8
900 GeV
0.4
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
0
2
4
6
8
10
12
14
16
18
0
5
10
15
20
PTmax or PT(chgjet#1) (GeV/c)
25
30
35
40
45
50
PT(chgjet#1) GeV/c
"Transverse" Charged Particle Density: dN/dhdf
3.0
CMS Preliminary
Ratio: 7 TeV/900 GeV
I am surprised that the
Tunes did not do a better job
of predicting the behavior of
the “underlying event” at
900 GeV and 7 TeV!
data uncorrected
pyDW + SIM
2.0
1.0
7 TeV / 900 GeV
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
0
2
4
6
8
10
12
14
16
18
PT(chgjet#1) (GeV/c)
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 32
PYTHIA Tune DW
How well did we do at predicting the “underlying event” at 900 GeV and 7 TeV?
"Transverse" Charged Particle Density: dN/dhdf
1.2
CMS Preliminary
CMS Preliminary
ChgJet#1
data uncorrected
pyDW + SIM
0.6
Charged Particle Density
"Transverse" Charged Density
"Transverse" Charged Particle Density: dN/dhdf
0.8
PTmax
0.4
0.2
900 GeV
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
7 TeV
data uncorrected
pyDW + SIM
0.8
900 GeV
0.4
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
0
2
4
6
8
10
12
14
16
18
0
5
10
15
20
PTmax or PT(chgjet#1) (GeV/c)
25
30
35
40
45
50
PT(chgjet#1) GeV/c
"Transverse" Charged Particle Density: dN/dhdf
3.0
CMS Preliminary
Ratio: 7 TeV/900 GeV
I am surprised that the
Tunes did as well as they did
at predicting the behavior of
the “underlying event” at
900 GeV and 7 TeV!
data uncorrected
pyDW + SIM
2.0
1.0
7 TeV / 900 GeV
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
0
2
4
6
8
10
12
14
16
18
PT(chgjet#1) (GeV/c)
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 33
PYTHIA Tune DW
"Transverse" Charged Particle "Transverse"
Density: dN/dhdf
1.2
CMS Preliminary
PTmax
0.4
0.2
0.0
0
2
4
CMS Preliminary
ChgJet#1
CMS
Preliminary
data uncorrected
pyDW + SIM
0.6
"Transverse"
Charged Particle Density: dN/dhdf
Charged Particle1.2Density:
dN/dhdf
6
Charged Particle Density
0.8
Charged Particle Density
"Transverse" Charged Density
How well did we do at predicting the “underlying event” at 900 GeV and 7 TeV?
data uncorrected
theory + SIM
0.8
900 GeV
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
P0
0.4
8
10
12
14
16
7 TeV
data uncorrected
py8
pyDW + SIM
0.8
900 GeV
0.4
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
18
0
5
10
15
20
PTmax or PT(chgjet#1) (GeV/c)
25
30
35
40
45
50
PT(chgjet#1) GeV/c
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
0
5
10
15
20
25
30
I am surprised
that
the
PT(chgjet#1) GeV/c
Tunes did as well as they did
at predicting the behavior of
the “underlying event” at
900 GeV and 7 TeV!
"Transverse" Charged Particle Density: dN/dhdf
35
3.0
40
45
50
Ratio: 7 TeV/900 GeV
CMS Preliminary
data uncorrected
pyDW + SIM
2.0
1.0
7 TeV / 900 GeV
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
0
2
4
6
8
10
12
14
16
18
PT(chgjet#1) (GeV/c)
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 34
PYTHIA Tune DW
"Transverse" Charged Particle "Transverse"
Density: dN/dhdf
1.2
CMS Preliminary
PTmax
0.4
0.2
0.0
0
2
4
CMS Preliminary
ChgJet#1
CMS
Preliminary
data uncorrected
pyDW + SIM
0.6
"Transverse"
Charged Particle Density: dN/dhdf
Charged Particle1.2Density:
dN/dhdf
6
Charged Particle Density
0.8
Charged Particle Density
"Transverse" Charged Density
How well did we do at predicting the “underlying event” at 900 GeV and 7 TeV?
data uncorrected
theory + SIM
0.8
900 GeV
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
P0
0.4
8
10
12
14
16
18
7 TeV
data uncorrected
py8
pyDW + SIM
0.8
900 GeV
0.4
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
No UE “plateau”!
0
5
10
0.0
15
20
PTmax or PT(chgjet#1) (GeV/c)
25
30
35
40
45
50
PT(chgjet#1) GeV/c
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
0
5
10
15
20
25
30
I am surprised
that
the
PT(chgjet#1) GeV/c
Tunes did as well as they did
at predicting the behavior of
the “underlying event” at
900 GeV and 7 TeV!
"Transverse" Charged Particle Density: dN/dhdf
35
3.0
40
45
50
Ratio: 7 TeV/900 GeV
CMS Preliminary
data uncorrected
pyDW + SIM
2.0
1.0
7 TeV / 900 GeV
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
0
2
4
6
8
10
12
14
16
18
PT(chgjet#1) (GeV/c)
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 35
PYTHIA Tune Z1
 All my previous tunes (A, DW, DWT, D6,
D6T, CW, X1, and X2) were PYTHIA 6.4
tunes using the old Q2-ordered parton
showers and the old MPI model (really 6.2
tunes)!
 I believe that it is time to move to PYTHIA
6.4 (pT-ordered parton showers and new
MPI model)!
 Tune Z1: I started with the parameters of
ATLAS Tune AMBT1, but I changed LO* to
CTEQ5L and I varied PARP(82) and PARP(90)
to get a very good fit of the CMS UE data at 900
GeV and 7 TeV.
 The ATLAS Tune ABT1 was designed to fit the
inelastic data for Nchg ≥ 6 and to fit the PTmax
UE data with PTmax > 10 GeV/c. Tune
AMBT1 is primarily a min-bias tune, while
Tune Z1 is a UE tune!
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
PARP(90)
PARP(82)
Color
Connections
Diffraction
Outgoing Parton
PT(hard)
Initial-State Radiation
Proton
Proton
Underlying Event
Outgoing Parton
Underlying Event
Final-State
Radiation
UE&MB@CMS
Page 36
PYTHIA Tune Z1
Tune Z1
(R. Field CMS)
Tune AMBT1
(ATLAS)
CTEQ5L
LO*
PARP(82) – MPI Cut-off
1.932
2.292
PARP(89) – Reference energy, E0
1800.0
1800.0
PARP(90) – MPI Energy Extrapolation
0.275
0.25
PARP(77) – CR Suppression
1.016
1.016
PARP(78) – CR Strength
0.538
0.538
0.1
0.1
PARP(83) – Matter fraction in core
0.356
0.356
PARP(84) – Core of matter overlap
0.651
0.651
PARP(62) – ISR Cut-off
1.025
1.025
PARP(93) – primordial kT-max
10.0
10.0
MSTP(81) – MPI, ISR, FSR, BBR model
21
21
MSTP(82) – Double gaussion matter distribution
4
4
MSTP(91) – Gaussian primordial kT
1
1
MSTP(95) – strategy for color reconnection
6
6
Parameter
Parton Distribution Function
Parameters not
shown are the
PYTHIA 6.4 defaults!
PARP(80) – Probability colored parton from BBR
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 37
PYTHIA Tune Z1
Tune Z2 with CTEQ6L
is coming soon!
Tune Z1
(R. Field CMS)
Tune AMBT1
(ATLAS)
CTEQ5L
LO*
PARP(82) – MPI Cut-off
1.932
2.292
PARP(89) – Reference energy, E0
1800.0
1800.0
PARP(90) – MPI Energy Extrapolation
0.275
0.25
PARP(77) – CR Suppression
1.016
1.016
PARP(78) – CR Strength
0.538
0.538
0.1
0.1
PARP(83) – Matter fraction in core
0.356
0.356
PARP(84) – Core of matter overlap
0.651
0.651
PARP(62) – ISR Cut-off
1.025
1.025
PARP(93) – primordial kT-max
10.0
10.0
MSTP(81) – MPI, ISR, FSR, BBR model
21
21
MSTP(82) – Double gaussion matter distribution
4
4
MSTP(91) – Gaussian primordial kT
1
1
MSTP(95) – strategy for color reconnection
6
6
Parameter
Parton Distribution Function
Parameters not
shown are the
PYTHIA 6.4 defaults!
PARP(80) – Probability colored parton from BBR
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 38
PYTHIA Tune Z1
"Transverse" Charged Particle Density: dN/dhdf
"Transverse" Charged Particle Density: dN/dhdf
1.2
1.2
CMS Preliminary
D6T
7 TeV
data uncorrected
Theory + SIM
Charged Particle Density
Charged Particle Density
CMS Preliminary
0.8
900 GeV
DW
0.4
CMS
7 TeV
data uncorrected
pyZ1 + SIM
0.8
900 GeV
0.4
CMS
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
0.0
0
5
10
15
20
25
30
35
40
45
50
0
5
10
15
20
25
30
35
40
45
50
PT(chgjet#1) GeV/c
PT(chgjet#1) GeV/c
 CMS preliminary data at 900 GeV and 7 TeV  CMS preliminary data at 900 GeV and 7 TeV
on the “transverse” charged particle density,
on the “transverse” charged particle density,
dN/dhdf, as defined by the leading charged
dN/dhdf, as defined by the leading charged
particle jet (chgjet#1) for charged particles
particle jet (chgjet#1) for charged particles
with pT > 0.5 GeV/c and |h| < 2.0. The data
with pT > 0.5 GeV/c and |h| < 2.0. The data
are uncorrected and compared with PYTHIA
are uncorrected and compared with PYTHIA
Tune DW and D6T after detector simulation
Tune Z1 after detector simulation (SIM).
(SIM).
Color reconnection suppression.
Color reconnection strength.
Hadron Collider Physics Symposium
Toronto August 23, 2010
Tune Z1 (CTEQ5L)
PARP(82) = 1.932
PARP(90) = 0.275
PARP(77) = 1.016
PARP(78) = 0.538
Rick Field – Florida/CDF/CMS
Tune Z1 is a PYTHIA 6.4 using
pT-ordered parton showers and
the new MPI model!
Page 39
PYTHIA Tune Z1
"Transverse" Charged PTsum Density: dPT/dhdf
CMS Preliminary
D6T
data uncorrected
Theory + SIM
1.2
Charged PTsum Density (GeV/c)
Charged PTsum Density (GeV/c)
"Transverse" Charged PTsum Density: dPT/dhdf
1.6
7 TeV
0.8
DW
900 GeV
CMS
0.4
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
0
5
10
15
20
25
30
35
40
45
50
1.6
CMS Preliminary
7 TeV
data uncorrected
pyZ1 + SIM
1.2
0.8
900 GeV
CMS
0.4
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
0
5
PT(chgjet#1) (GeV/c)
10
15
20
25
30
35
40
45
50
PT(chgjet#1) (GeV/c)
 CMS preliminary data at 900 GeV and 7 TeV  CMS preliminary data at 900 GeV and 7 TeV
on the “transverse” charged PTsum density,
on the “transverse” charged PTsum density,
dPT/dhdf, as defined by the leading charged
dPT/dhdf, as defined by the leading charged
particle jet (chgjet#1) for charged particles
particle jet (chgjet#1) for charged particles
with pT > 0.5 GeV/c and |h| < 2.0. The data
with pT > 0.5 GeV/c and |h| < 2.0. The data
are uncorrected and compared with PYTHIA
are uncorrected and compared with PYTHIA
Tune DW and D6T after detector simulation
Tune Z1 after detector simulation (SIM).
(SIM).
Color reconnection suppression.
Color reconnection strength.
Hadron Collider Physics Symposium
Toronto August 23, 2010
Tune Z1 (CTEQ5L)
PARP(82) = 1.932
PARP(90) = 0.275
PARP(77) = 1.016
PARP(78) = 0.538
Rick Field – Florida/CDF/CMS
Tune Z1 is a PYTHIA 6.4 using
pT-ordered parton showers and
the new MPI model!
Page 40
PYTHIA Tune Z1
"Transverse" Charged PTsum Density: dPT/dhdf
1.2
1.5
RDF Preliminary
RDF Preliminary
7 TeV
ATLAS corrected data
Tune Z1 generator level
PTsum Density (GeV/c)
"Transverse" Charged Density
"Transverse" Charged Particle Density: dN/dhdf
0.8
900 GeV
0.4
ATLAS
7 TeV
ATLAS corrected data
Tune Z1 generator level
1.0
900 GeV
0.5
ATLAS
Charged Particles (|h|<2.5, PT>0.5 GeV/c)
Charged Particles (|h|<2.5, PT>0.5 GeV/c)
0.0
0.0
0
2
4
6
8
10
12
14
16
18
20
0
2
PTmax (GeV/c)
Hadron Collider Physics Symposium
Toronto August 23, 2010
6
8
10
12
14
16
18
PTmax (GeV/c)
 ATLAS preliminary data at 900 GeV and 7
TeV on the “transverse” charged particle
density, dN/dhdf, as defined by the leading
charged particle (PTmax) for charged
particles with pT > 0.5 GeV/c and |h| < 2.5.
The data are corrected and compared with
PYTHIA Tune Z1 at the generator level.
Color reconnection suppression.
Color reconnection strength.
4
 ATLAS preliminary data at 900 GeV and 7
TeV on the “transverse” charged PTsum
density, dPT/dhdf, as defined by the leading
charged particle (PTmax) for charged
particles with pT > 0.5 GeV/c and |h| < 2.5.
The data are corrected and compared with
PYTHIA Tune Z1 at the generrator level.
Tune Z1 (CTEQ5L)
PARP(82) = 1.932
PARP(90) = 0.275
PARP(77) = 1.016
PARP(78) = 0.538
Rick Field – Florida/CDF/CMS
Tune Z1 is a PYTHIA 6.4 using
pT-ordered parton showers and
the new MPI model!
Page 41
20
PYTHIA Tune Z1
"Transverse" Charged Particle Density: dN/dhdf
"Transverse" Charged Particle Density: dN/dhdf
3.0
3.0
CMS Preliminary
DW
D6T
data uncorrected
theory + SIM
Ratio: 7 TeV/900 GeV
Ratio: 7 TeV/900 GeV
CMS Preliminary
2.0
P0
1.0
CW
CMS
7 TeV / 900 GeV
data uncorrected
pyZ1 + SIM
2.0
1.0
CMS
7 TeV / 900 GeV
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
0.0
0
2
4
6
8
10
12
14
16
18
0
2
PT(chgjet#1) (GeV/c)
6
8
10
12
14
16
18
PT(chgjet#1) (GeV/c)
 Ratio of CMS preliminary data at 900 GeV
and 7 TeV (7 TeV divided by 900 GeV) on the
“transverse” charged particle density as
defined by the leading charged particle jet
(chgjet#1) for charged particles with pT > 0.5
GeV/c and |h| < 2.0. The data are
uncorrected and compared with PYTHIA
Tune DW, D6T, CW, and P0 after detector
simulation (SIM).
Hadron Collider Physics Symposium
Toronto August 23, 2010
4
 Ratio of CMS preliminary data at 900 GeV
and 7 TeV (7 TeV divided by 900 GeV) on the
“transverse” charged particle density as
defined by the leading charged particle jet
(chgjet#1) for charged particles with pT > 0.5
GeV/c and |h| < 2.0. The data are
uncorrected and compared with PYTHIA
Tune Z1 after detector simulation (SIM).
Rick Field – Florida/CDF/CMS
Page 42
PYTHIA Tune Z1
"Transverse" Charged PTsum Density: dPT/dhdf
3.0
D6T
CMS Preliminary
CMS Preliminary
DW
data uncorrected
theory + SIM
Ratio: 7 TeV/900 GeV
Ratio: 7 TeV/900 GeV
"Transverse" Charged PTsum Density: dPT/dhdf
3.0
2.0
P0
CW
1.0
CMS
7 TeV / 900 GeV
data uncorrected
pyZ1 + SIM
2.0
1.0
CMS
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
7 TeV / 900 GeV
0.0
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
0
2
4
6
8
10
12
14
16
18
0
2
PT(chgjet#1) (GeV/c)
6
8
10
12
14
16
18
PT(chgjet#1) (GeV/c)
 Ratio of CMS preliminary data at 900 GeV
and 7 TeV (7 TeV divided by 900 GeV) on the
“transverse” charged PTsum density as
defined by the leading charged particle jet
(chgjet#1) for charged particles with pT > 0.5
GeV/c and |h| < 2.0. The data are
uncorrected and compared with PYTHIA
Tune DW, D6T, CW, and P0 after detector
simulation (SIM).
Hadron Collider Physics Symposium
Toronto August 23, 2010
4
 Ratio of CMS preliminary data at 900 GeV
and 7 TeV (7 TeV divided by 900 GeV) on the
“transverse” charged PTsum density as
defined by the leading charged particle jet
(chgjet#1) for charged particles with pT > 0.5
GeV/c and |h| < 2.0. The data are
uncorrected and compared with PYTHIA
Tune Z1 after detector simulation (SIM).
Rick Field – Florida/CDF/CMS
Page 43
PYTHIA Tune Z1
"Transverse" Charged Particle Density: dN/dhdf
"Transverse" Charged PTsum Density: dPT/dhdf
4.0
3.0
RDF Preliminary
RDF Preliminary
ATLAS corrected data
Tune Z1 generator level
ATLAS corrected data
Tune Z1 generator level
Ratio: 7 TeV/900 GeV
Ratio: 7 TeV/900 GeV
4.0
2.0
ATLAS
1.0
7 TeV / 900 GeV
3.0
2.0
1.0
ATLAS
7 TeV / 900 GeV
Charged Particles (|h|<2.5, PT>0.5 GeV/c)
0.0
Charged Particles (|h|<2.5, PT>0.5 GeV/c)
0.0
0
1
2
3
4
5
6
7
8
9
10
11
12
0
1
PTmax (GeV/c)
3
4
5
6
7
8
9
10
11
12
PTmax (GeV/c)
 Ratio of the ATLAS preliminary data on the
charged particle density in the “transverse”
region for charged particles (pT > 0.5 GeV/c,
|h| < 2.5) at 900 GeV and 7 TeV as defined by
PTmax compared with PYTHIA Tune Z1 at
the generator level.
Hadron Collider Physics Symposium
Toronto August 23, 2010
2
 Ratio of the ATLAS preliminary data on the
charged PTsum density in the “transverse”
region for charged particles (pT > 0.5 GeV/c,
|h| < 2.5) at 900 GeV and 7 TeV as defined by
PTmax compared with PYTHIA Tune Z1 at
the generator level.
Rick Field – Florida/CDF/CMS
Page 44
PYTHIA Tune Z1
"Transverse" Charged Particle Density: dN/dhdf
"Transverse" Charged Particle Density: dN/dhdf
1.2
Charged Particle Density
"Transverse" Charged Density
1.2
CMS Preliminary
7 TeV
data uncorrected
pyZ1 + SIM
0.8
900 GeV
0.4
CMS
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
CDF Run 2
1.96 TeV
data corrected
pyZ1 generator level
0.8
0.4
"Leading Jet"
MidPoint R=0.7 |h(jet#1)|<2
CDF
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
0
5
10
15
20
25
30
35
40
45
50
0
50
PT(chgjet#1) GeV/c
100
150
200
250
300
350
400
PT(jet#1) (GeV/c)
 CMS preliminary data at 900 GeV and 7 TeV  CDF published data at 1.96 TeV on the
on the “transverse” charged particle density,
“transverse” charged particle density,
dN/dhdf, as defined by the leading charged
dN/dhdf, as defined by the leading
particle jet (chgjet#1) for charged particles
calorimeter jet (jet#1) for charged particles
with pT > 0.5 GeV/c and |h| < 2. The data are
with pT > 0.5 GeV/c and |h| < 1.0. The data
uncorrected and compared with PYTHIA
are corrected and compared with PYTHIA
Tune Z1 after detector simulation.
Tune Z1 at the generator level.
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 45
PYTHIA Tune Z1
Oops Tune Z1 is
"Transverse"
slightly high
at CDF!Charged Particle Density: dN/dhdf
"Transverse" Charged Particle Density: dN/dhdf
1.2
Charged Particle Density
"Transverse" Charged Density
1.2
CMS Preliminary
7 TeV
data uncorrected
pyZ1 + SIM
0.8
900 GeV
0.4
CMS
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
CDF Run 2
1.96 TeV
data corrected
pyZ1 generator level
0.8
0.4
"Leading Jet"
MidPoint R=0.7 |h(jet#1)|<2
CDF
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
0
5
10
15
20
25
30
35
40
45
50
0
50
PT(chgjet#1) GeV/c
100
150
200
250
300
350
400
PT(jet#1) (GeV/c)
 CMS preliminary data at 900 GeV and 7 TeV  CDF published data at 1.96 TeV on the
on the “transverse” charged particle density,
“transverse” charged particle density,
dN/dhdf, as defined by the leading charged
dN/dhdf, as defined by the leading
particle jet (chgjet#1) for charged particles
calorimeter jet (jet#1) for charged particles
with pT > 0.5 GeV/c and |h| < 2. The data are
with pT > 0.5 GeV/c and |h| < 1.0. The data
uncorrected and compared with PYTHIA
are corrected and compared with PYTHIA
Tune Z1 after detector simulation.
Tune Z1 at the generator level.
Hadron Collider Physics Symposium
Toronto August 23, 2010
Rick Field – Florida/CDF/CMS
Page 46
Summary & Conclusions
I am surprised that the Tunes did as well as
they did at predicting the behavior of the
“underlying event” at 900 GeV and 7 TeV!
Remember this is “soft” QCD!
I still dream of a
“universal” tune that
fits the UE at all
energies! Need to
simultaneously tune
LHC plus CDF
(“professor” tune)!
Tune Z1 does nice fob of fitting the
CMS and ATLAS UE data at 900 GeV
and 7 TeV! But Tune Z1 is a little high
PYTHIA 6.4 pT-ordered parton showers and new MPI model!
at CDF (1.96 TeV)!
Outgoing Parton
I am surprised that PYTHIA 8 does so
well (right out of the box, Tune 1)!
Slight problem with the UE “plateau”
which is fixed in version 8.142.
Next Step: More PYTHIA 6.4 and
PYTHIA 8 tunes. Time to look more
closely at Sherpa and HERWIG++!
Hadron Collider Physics Symposium
Toronto August 23, 2010
PT(hard)
Initial-State Radiation
Proton
Proton
Underlying Event
Outgoing Parton
Underlying Event
Final-State
Radiation
And CMS must correct the data
so it can be used outside CMS!
Rick Field – Florida/CDF/CMS
Page 47