High Energy QCD after the start of the LHC
Physics of the Underlying Event
Rick Field
University of Florida
CMS
Outline
 How well did we do at predicting the behavior of the “underlying
event” at the LHC (900 GeV and 7 TeV)?
 How universal are the QCD Monte-Carlo model tunes?
 Examine the connection between the “underlying event” in a hard
ATLAS
scattering process (UE) and “min-bias” collisions (MB).
 How well can we predict “min-bias” collisions at the LHC?
 Strange particle and baryon production at the LHC.
+
K
u s
p
Kshort
d s +d s
K-
u s
GGI Florence, Italy
September 14, 2011
Outgoing Parton
“Minimum Bias” Collisions
PT(hard)
Initial-State Radiation
uud

ud s
Proton
Proton
Underlying Event
Underlying Event
 
dss
Outgoing Parton
Final-State
Radiation
Rick Field – Florida/CDF/CMS
UE&MB@CMS
Page 1
QCD Monte-Carlo Models:
High Transverse Momentum Jets
Hard Scattering
Initial-State Radiation
Hard Scattering “Jet”
Initial-State Radiation
“Jet”
Outgoing Parton
PT(hard)
Outgoing Parton
PT(hard)
Proton
“Hard Scattering” Component
AntiProton
Final-State Radiation
Outgoing Parton
Underlying Event
Underlying Event
Proton
“Jet”
Final-State Radiation
AntiProton
Underlying Event
Outgoing Parton
Underlying Event
“Underlying Event”
 Start with the perturbative 2-to-2 (or sometimes 2-to-3) parton-parton scattering and add initial and finalstate gluon radiation (in the leading log approximation or modified leading log approximation).
 The “underlying event” consists of the “beam-beam remnants” and from particles arising from soft or
semi-soft multiple parton interactions (MPI).
The “underlying
event” is“jet”
an unavoidable
 Of course the outgoing colored partons fragment
into hadron
and inevitably “underlying event”
background to most collider observables
observables receive contributions from initial
and final-state radiation.
and having good understand of it leads to
more precise collider measurements!
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 2
QCD Monte-Carlo Models:
Lepton-Pair Production
Lepton-Pair
Production
High
PT Z-Boson
Production
Anti-Lepton
Outgoing Parton
Initial-State
Initial-State Radiation
Radiation
High P
T Z-Boson Production
Lepton-Pair
Production
Initial-State
Initial-StateRadiation
Radiation
“Jet”
Proton
Proton
Final-State Radiation
Outgoing
Parton
Anti-Lepton
Final-State Radiation
“Hard Scattering” Component
AntiProton
AntiProton
Underlying Event
Lepton
Z-boson
Underlying Event
Proton
Lepton
Z-boson
AntiProton
Underlying Event
Underlying Event
“Underlying Event”

Start with the perturbative Drell-Yan muon pair production and add initial-state gluon radiation (in the
leading log approximation or modified leading log approximation).
 The “underlying event” consists of the “beam-beam remnants” and from particles arising from soft or
semi-soft multiple parton interactions (MPI).
 Of course the outgoing colored partons fragment into hadron “jet” and inevitably “underlying event”
observables receive contributions from initial-state radiation.
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 3
“Towards”, “Away”, “Transverse”
“Leading Jet”
Jet #1 Direction

“Toward”
“Transverse”
“Transverse”
“Away”
Charged
PTsum
Density
(GeV/c)
Average
Charged
Density
Charged PTsum
ParticleDensity:
Density:dPT/dhd
dN/dhd
Charged
5
100.0
CDFCDF
RunRun
2 Preliminary
2 Preliminary
4
data corrected
data corrected
pyA generator level
pyA generator level
10.0
3
"Toward"
"Away"
"Toward"
"Away"
Factor of ~16
"Transverse" "Leading Jet"
Factor of MidPoint
~4.5 R=0.7 |h(jet#1)|<2
2
1.0
"Transverse"
1
"Leading Jet"
MidPoint R=0.7 |h(jet#1)|<2
ChargedParticles
Particles(|h|<1.0,
(|h|<1.0,PT>0.5
PT>0.5GeV/c)
GeV/c)
Charged
0 0.1
0 0
50 50
100100
150
150
200
200
250
250
300
300
350
350
400
400
PT(jet#1)
PT(jet#1)(GeV/c)
(GeV/c)

charged
particles,
dN/dhd,
pT > 0.5with
GeV/c
< 1 for
 CDF
CDF data
data at
at 1.96
1.96 TeV
TeV on
on the
the density
chargedofparticle
scalar
pT sum
density,with
dPT/dhd,
pT >and
0.5|h|
GeV/c
and
“leading
eventsjet”
as aevents
function
the leading
jetleading
pT for the
“away”, and
“transverse”
|h| < 1 forjet”
“leading
as aoffunction
of the
jet “toward”,
pT for the “toward”,
“away”,
and
regions.
The
data
are
corrected
to
the
particle
level
(with
errors
that
include
both
the
statistical
“transverse” regions. The data are corrected to the particle level (with errors that include both error
the and
the
systematic
and areuncertainty)
compared with
Tune with
A at PYTHIA
the particle
level
generator
statistical
erroruncertainty)
and the systematic
and PYTHIA
are compared
Tune
A (i.e.
at the
particle
level).
level (i.e. generator level).
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 4
Charged Particle Density
Charged
Particle
Density:
dN/dhd
"Transverse"
Charged
Density:
dN/dhdCharged Particle Density:
Charged
ParticleParticle
Density:
dN/dhd
"Away"
Charged
Particle
Density:
dN/dhd
"Transverse"
dN/dhd
2
0.6
"Z-Boson"
1
0.3
0
0.0
00
20
20
40
40
60
60
Average
ChargedDensity
Density
"Away" Charged
RDF Preliminary
data
corrected
data
corrected
generator
levellevel
theory
pyA
generator
0.9
3
34
1.2
CDFRun
Run2 2Preliminary
Preliminary
CDF
Charged Particle Density
"Transverse"
ChargedDensity
Density
Average Charged
1.2
4
data corrected
"Leading
Jet"
"Away"
pyDW generator level
0.8
"Toward"
"Leading Jet"
MidPoint R=0.7 |h(jet#1)|<2
0.4
"Transverse"
80
80
CDF Run 2 Preliminary
CDF 1.96
TeV
data
data corrected
corrected
Leading
Jet
generator
level theory
pyAW generator
level
3
2
0.0
"Drell-Yan Production"
70 < M(pair) < 110 GeV
2
1
1
"Transverse"
"Z-Boson"
100
100
00
120
120
140
140
0
50
PT(jet#1)
(GeV/c) (GeV/c)
PT(jet#1)
or PT(Z-Boson)
160
160
100
180
180
200
200
150
00
200
20
250
PT(jet#1) GeV/c
Z-Boson Direction


Outgoing Parton
40
20
300
60
Underlying Event
“Away”
120
60
140
High PT Z-Boson Production
160
80
180
200
100
Outgoing Parton
“Toward”
Proton
AntiProton
Underlying Event
100
Initial-State Radiation
Initial-State Radiation
Proton
80
40
Charged
Particles
(|h|<1.0,
PT>0.5
GeV/c)
Charged
Particles
(|h|<1.0,
PT>0.5
GeV/c)
excluding the lepton-pair
350
400
PT(jet#1)
or PT(Z-Boson)
(GeV/c)
PT(Z-Boson)
(GeV/c)
PT(hard)
“Toward”
“Transverse”
"Away"
Charged Particles (PT>0.5 GeV/c, |h| <"Toward"
1.0)
Charged
Charged Particles
Particles(|h|<1.0,
(|h|<1.0,PT>0.5
PT>0.5GeV/c)
GeV/c)
Jet #1 Direction
“Transverse”
"Leading Jet"
“Transverse”
AntiProton
“Transverse”
“Away”
Outgoing Parton
Final-State
Radiation
Z-boson
 CDF data at 1.96 TeV on the density of charged particles, dN/dhd, with pT > 0.5 GeV/c and |h| < 1 for “Z-
Boson” and “Leading Jet” events as a function of the leading jet pT or PT(Z) for the “toward”, “away”, and
“transverse” regions. The data are corrected to the particle level and are compared with PYTHIA Tune AW
and Tune A, respectively, at the particle level (i.e. generator level).
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 5
Charged PTsum Density
2.0
100.0
20
10.0
corrected
datadata
corrected
pyA generator
level
generator
level theory
1.5
10.0
1.0
0.5
"Z-Boson"
2020
4040
6060
RDF Preliminary
data
corrected
"Leading
Jet"
pyDW generator level
"Toward"1.2
1.0
0.00.1
0 0
Charged
Density(GeV/c)
(GeV/c)
"Away" PTsum
PTsum Density
1.6
CDF
Run
2 Preliminary
CDF
Run
2 Preliminary
PTsum Density (GeV/c)
Charged PTsum
Density
"Transverse"
PTsum
Density(GeV/c)
(GeV/c)
Charged
PTsum
Density:
dPT/dhd
"Away"
Charged
PTsum
Density:
dPT/dhd
"Transverse"
Charged
Density:
dPT/dhd
Charged
PTsum PTsum
Density:
dPT/dhd
"Transverse"
Charged PTsum Density:
dPT/dhd
8080
"Away"
0.8"Transverse"
"Leading Jet"
MidPoint R=0.7 |h(jet#1)|<2
CDF
Run
Preliminary
CDF
Run
22
Preliminary
"Away"
"Leading Jet"
data
corrected
data
corrected
pyAW generator
level
generator
level theory
15
"Transverse"
"Z-Boson"
10
1.0
CDF 1.96 TeV
Leading Jet
"Toward"
5
"Drell-Yan Production"
0.4
70 < M(pair) < 110 GeV
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
Charged Particles (|h|<1.0, PT>0.5 GeV/c) Charged Particles (PT>0.5 GeV/c, |h| < 1.0)
0.0
100
100
120
120
140
140
160
160
0
50
(GeV/c)
PT(jet#1)PT(jet#1)
or PT(Z-Boson)
(GeV/c)
180
180
100
0
0.1
00
200
200
150
200
20
40
20
250
300
60
Charged
ChargedParticles
Particles(|h|<1.0,
(|h|<1.0,PT>0.5
PT>0.5GeV/c)
GeV/c)
excluding the lepton-pair
80
40
100
120
60
140
160
80
180
200
100
350
PT(jet#1)
or400
PT(Z-Boson)
(GeV/c)
PT(Z-Boson)
(GeV/c)
PT(jet#1) GeV/c
Jet #1 Direction
Outgoing Parton

Z-Boson Direction

High PT Z-Boson Production
PT(hard)
“Toward”
“Transverse”
Initial-State Radiation
Initial-State Radiation
Proton
“Transverse”
“Toward”
AntiProton
Underlying Event
Underlying Event
“Away”
Outgoing Parton
Proton
“Transverse”
AntiProton
“Transverse”
“Away”
Outgoing Parton
Final-State
Radiation
Z-boson
 CDF data at 1.96 TeV on the charged scalar PTsum density, dPT/dhd, with pT > 0.5 GeV/c and |h| < 1 for “ZBoson” and “Leading Jet” events as a function of the leading jet pT or PT(Z) for the “toward”, “away”, and
“transverse” regions. The data are corrected to the particle level and are compared with PYTHIA Tune AW
and Tune A, respectively, at the particle level (i.e. generator level).
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 6
Z-Boson: “Towards”, Transverse”,
& “TransMIN” Charge Density
Charged
Particle
Density:
dN/dhd
Charged
Particle
Density:
dN/dhd
"TransMIN"
Charged
Particle
Density:
dN/dhd
"Toward"
Charged
Particle
Density:
dN/dhd
"TransMIN" Charged Particle Density:
dN/dhd
High
PT Z-Boson
Production
Outgoing Parton
datagenerator
correctedlevel
pyAW
generator level theory
"Toward"
0.3
0.3
"Drell-Yan Production"
Production"
"Drell-Yan
70 << M(pair)
M(pair) <
70
< 110
110 GeV
GeV
HW
20
20
0.6
pyDW
data corrected
generator level theory
0.4
0.2
pyAW
Charged
Charged Particles
Particles (|h|<1.0,
(|h|<1.0, PT>0.5
PT>0.5 GeV/c)
GeV/c)
"Z-Boson"
excluding
excluding the
the lepton-pair
lepton-pair
0.0
0.0
00
CDF Run 2 Preliminary
"Transverse
ATLAS
JIM
0.6
0.6
0.0
60
60 0
40
40
PT(Z-Boson)
PT(Z-Boson) (GeV/c)
(GeV/c)
Initial-State Radiation
0.9
0.6
0.8
Charged
Density
"TransMIN"
Charged
Density
CDF Run 2 Preliminary
CDF Run
2 Preliminary
data corrected
"TransMIN" Charged Density
Charged
Density
"Toward"
Charged
Density
0.9
0.9
Initial-State Radiation
CDF Run 2 Preliminary
data corrected
Proton
generator
level theory
pyAW
generator
level
0.6
0.4
"Leading Jet"
"Drell-Yan Production"
"Drell-Yan Production"
70 < M(pair) < 110 GeV
70 < M(pair) < 110 GeV
AntiProtonpyDW
ATLAS
JIM
"Toward"
0.3
0.2
Z-boson
Z-boson
"transMIN"
Charged
Charged Particles
Particles (|h|<1.0,
(|h|<1.0, PT>0.5
PT>0.5 GeV/c)
GeV/c)
pyAW
HW
excluding
excluding the
the lepton-pair
lepton-pair
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
80 40
20 80
100 80
60 100
1000
120
20
140
PT(jet#1) or PT(Z-Boson) (GeV/c)
160
40
180
60
200
100
PT(Z-Boson) (GeV/c)
Z-Boson Direction
Z-BosonDirection


“Toward”
“Toward”
“Transverse”
80
“TransMAX”
“Transverse”
“TransMIN”
“Away”
“Away”
 Data at 1.96 TeV on the density of charged particles, dN/dhd, with pT > 0.5 GeV/c and |h| < 1 for
“Z-Boson” events as a function of PT(Z) for the “toward” and “transverse” regions. The data are
corrected to the particle level (with errors that include both the statistical error and the systematic
uncertainty) and are compared with PYTHIA Tune AW and HERWIG (without MPI) at the particle
level (i.e. generator level).
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 7
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

“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
“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).
GGI Florence, Italy
September 14, 2011
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)

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 9
Z-Boson: “Towards” Region
RDF LHC
Prediction!
"Toward" Charged Particle Density:
dN/dhd
"Toward" Charged Particle Density: dN/dhd
RDF Preliminary
PY Tune AW
PY Tune DW
generator level
RDF Preliminary
Drell-Yan
1.96 TeV
"Toward" Charged Density
"Toward" Charged Density
PY ATLAS
1.6
0.8
0.6
PY Tune DWT
generator level
1.2
Rick Field
MB&UE@CMS Workshop
0.8
CERN, November 6, 2009
0.4
PY64 Tune P329
PY64 Tune S320
0.2
70 < M(pair) < 110 GeV
PY Tune DW
PY64 Tune P329
PY64 Tune S320
0.4
70 < M(pair) < 110 GeV
Drell-Yan
14 TeV
If the LHC data are not in
the range shown here then
we learn new (QCD) physics!
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
0.0
0
25
50
75
100
125
150
0
25

“Transverse”
100
125
Z-BosonDirection

“Toward”
“Toward”
“Transverse”
75
Lepton-Pair PT (GeV/c)
Lepton-Pair PT (GeV/c)
Z-BosonDirection
50
Tevatron
LHC
“Transverse”
“Transverse”
“Away”
“Away”
 Data at 1.96 TeV on the density of charged particles, dN/dhd, with pT > 0.5 GeV/c and |h| < 1 for “Z-
Boson” events as a function of PT(Z) for the “toward” region from PYTHIA Tune AW, Tune DW, Tune
S320, and Tune P329 at the particle level (i.e. generator level).
 Extrapolations of PYTHIA Tune AW, Tune DW, Tune DWT, Tune S320, and Tune P329, and pyATLAS to
the LHC.
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 10
150
“Transverse” Charged Particle Density
PT(chgjet#1) Direction
"Transverse" Charged Particle Density: dN/dhd
"Transverse" Charged Density
0.8

RDF Preliminary
Fake Data
pyDW generator level
ChgJet#1
“Toward”
0.6
PTmax
“Transverse”
“Transverse”
0.4
Leading Charged
Particle Jet, chgjet#1.
“Away”
0.2
900 GeV
Prediction!
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
PTmax Direction
0.0
0
2
4
6
8
10
12
14
16
PTmax or PT(chgjet#1) (GeV/c)
“Toward”
 Fake data (from MC) at 900 GeV on the
“transverse” charged particle density,
dN/dhd, 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).
GGI Florence, Italy
September 14, 2011

18
Rick Field – Florida/CDF/CMS
“Transverse”
“Transverse”
Leading Charged
Particle, PTmax.
“Away”
Rick Field
MB&UE@CMS Workshop
CERN, November 6, 2009
Page 11
“Transverse” Charged Particle Density
"Transverse" Charged Particle Density: dN/dhd
"Transverse" Charged Particle Density: dN/dhd
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
Monte-Carlo!
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
Real Data!
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/dhd, 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).
GGI Florence, Italy
September 14, 2011
4
 CMS preliminary data at 900 GeV on the
“transverse” charged particle density,
dN/dhd, 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 12
“Transverse” Charged PTsum Density
"Transverse" Charged PTsum Density: dPT/dhd
"Transverse" Charged PTsum Density: dPT/dhd
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
Monte-Carlo!
CMS Preliminary
data uncorrected
pyDW + SIM
0.6
ChgJet#1
PTmax
0.4
0.2
900 GeV
Real Data!
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
18
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/dhd, as defined by the leading charged
dPT/dhd, 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
data (from PYTHIA Tune DW) are
are uncorrected and compared with
generated at the particle level (i.e. generator
PYTHIA Tune DW after detector simulation
level) assuming 0.5 M min-bias events at 900
(216,215 events in the plot).
GeV (361,595 events in the plot).
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 13
“Transverse” Charge Density
"Transverse" Charged Particle Density: dN/dhd
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
Prediction!
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
4
10
0.0
0
2
6
8
12
14
16
18
20
PTmax (GeV/c)
PTmax Direction

LHC
900 GeV
“Toward”
“Transverse”
PTmax Direction
900 GeV → 7 TeV
(UE increase ~ factor of 2)
“Transverse”
“Away”
~0.4 → ~0.8

“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).
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 14
PYTHIA Tune DW
"Transverse" Charged Particle Density: dN/dhd
"Transverse" Charged Particle Density: dN/dhd
3.0
1.2
CMS Preliminary
7 TeV
data uncorrected
pyDW + SIM
Ratio: 7 TeV/900 GeV
Charged Particle Density
CMS Preliminary
0.8
Ratio
CMS
900 GeV
0.4
data uncorrected
pyDW + SIM
2.0
CMS
1.0
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
5
10
15
20
25
30
35
40
45
50
0
2
4
6
8
10
12
14
16
18
PT(chgjet#1) (GeV/c)
PT(chgjet#1) GeV/c
 CMS preliminary data at 900 GeV and 7 TeV  Ratio of CMS preliminary data at 900 GeV
and 7 TeV on the “transverse” charged
on the “transverse” charged particle density,
particle density, dN/dhd, as defined by the
dN/dhd, as defined by the leading charged
leading charged particle jet (chgjet#1) for
particle jet (chgjet#1) for charged particles
charged particles with pT > 0.5 GeV/c and
with pT > 0.5 GeV/c and |h| < 2. The data are
|h| < 2. The data are uncorrected and
uncorrected and compared with PYTHIA
compared with PYTHIA Tune DW after
Tune DW after detector simulation.
PT(chgjet#1) Direction
PT(chgjet#1) Direction
detector simulation.


“Toward”
“Transverse”
“Toward”
“Transverse”
“Transverse”
“Away”
GGI Florence, Italy
September 14, 2011
“Transverse”
“Away”
Rick Field – Florida/CDF/CMS
Page 15
PYTHIA Tune DW
"Transverse" Charged Particle Density: dN/dhd
"Transverse" Charged Particle Density: dN/dhd
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
 Ratio of CMS preliminary data at 900 GeV
and 7 TeV on the “transverse” charged
particle density, dN/dhd, 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
PT(chgjet#1) Direction
detector simulation.

4
5
6
7
8
9
10
11
 Ratio of the ATLAS preliminary data at
900 GeV and 7 TeV on the “transverse”
charged particle density, dN/dhd, 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
PTmax Direction
Tune DW at the generator
level.

“Toward”
“Toward”
“Transverse”
“Transverse”
“Away”
GGI Florence, Italy
September 14, 2011
3
PTmax (GeV/c)
PT(chgjet#1) (GeV/c)
“Transverse”
2
“Transverse”
“Away”
Rick Field – Florida/CDF/CMS
Page 16
12
PYTHIA Tune DW
"Transverse" Charged PTsum Density: dPT/dhd
"Transverse" Charged PTsum Density: dPT/dhd
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
 Ratio of the CMS preliminary data at 900
GeV and 7 TeV on the “transverse” charged
PTsum density, dPT/dhd, 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
PT(chgjet#1) Direction
detector simulation.

4
5
6
7
8
9
10
11
12
 Ratio of the ATLAS preliminary data at 900
GeV and 7 TeV on the “transverse” charged
PTsum density, dPT/dhd, 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. PTmax Direction
“Toward”

“Toward”
“Transverse”
“Transverse”
“Away”
GGI Florence, Italy
September 14, 2011
3
PTmax (GeV/c)
PT(chgjet#1) (GeV/c)
“Transverse”
2
“Transverse”
“Away”
Rick Field – Florida/CDF/CMS
Page 17
PYTHIA Tune DW
"Transverse" Charged Particle Density: dN/dhd
"Transverse" Charged Particle Density: dN/dhd
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
 CMS preliminary data at 900 GeV and 7 TeV 
on the “transverse” charged particle density,
dN/dhd, 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.
16
18
20
ATLAS preliminary data at 900 GeV and 7
TeV on the “transverse” charged particle
density, dN/dhd, 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.
PT(chgjet#1) Direction
PTmax Direction


“Toward”
“Toward”
“Transverse”
“Transverse”
“Away”
GGI Florence, Italy
September 14, 2011
14
PTmax (GeV/c)
PT(chgjet#1) GeV/c
“Transverse”
12
“Transverse”
“Away”
Rick Field – Florida/CDF/CMS
Page 18
PYTHIA Tune DW
"Transverse" Charged PTsum Density: dPT/dhd
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/dhd
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
 CMS preliminary data at 900 GeV and 7
TeV on the “transverse” charged PTsum
density, dPT/dhd, 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
PT(chgjet#1) Direction
simulation.

8
10
12
14
16
18
 ATLAS preliminary data at 900 GeV and
7 TeV on the “transverse” charged PTsum
density, dPT/dhd, 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. PTmax Direction
“Toward”
“Toward”
“Transverse”
“Transverse”
“Away”
GGI Florence, Italy
September 14, 2011
6
PTmax (GeV/c)
PT(chgjet#1) (GeV/c)
“Transverse”
4
“Transverse”
“Away”
Rick Field – Florida/CDF/CMS
Page 19
20
Charged Particle Density
1.96 TeV
data corrected
pyDW generator level
Charged Particle Density
Average Charged Density
3
Drell-Yan Production
70 < M(pair) < 110 GeV
2
1
Average Charged Density
Large increase in the UE
in going from 1.96 TeV
Charged Particle Density: dN/dhd
Charged Particle Density: dN/dhd
"Toward" Charged Particle Density: dN/dhd
to 7 TeV as predicted by
3
Tune DW! 1.2 RDF Preliminary
CDF RunPYTHIA
2
CMS Preliminary
data corrected
"Away"
pyDW generator level
0.8
Drell-Yan
Production
Charged Particles
(|h|<1.0, PT>0.5
GeV/c)
excluding the lepton-pair
0
10
20
30
40
50
60
0
70
PT(lepton-pair) GeV/c
80
20
90
Initial-State Radiation
“Transverse”
“Transverse”
“Away”
"Toward"
Charged Particles (PT>0.5 GeV/c)
0 60
PT(lepton-pair) GeV/c
Outgoing Parton
T
"Transverse"
1
100
40
High P Z-Boson Production
CDF:Proton-Antiproton
Collisions at 1.96 GeV
Lepton Cuts: pT > 20 GeV |h| < 1.0
“Toward”
Proton
Mass Cut:
70 < M(lepton-pair) < 110
GeV
AntiProton
Charged Particles: pT > 0.5 GeV/c |h| < 1.0
Z-Boson Direction
"Away"
Drell-Yan Production
60 < M(pair) < 120 GeV
2
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
excluding the lepton-pair
0
0.0
0
CMS
CDF 1.96 TeV
0.4
"Transverse"
"Toward"
7 TeV
data corrected
CMS pyDW
7 TeV
generator level
2080
40
100
60
80
100
PT(lepton-pair) GeV/c
High P Z-Boson Production
CMS: Proton-Proton
Collisions at 7 GeV

Lepton Cuts: pT > 20 GeV |h| < 2.4
“Toward”
Mass Cut:Proton
60 < M(lepton-pair) < 120 Proton
GeV
Charged Particles: pT > 0.5 GeV/c |h| < 2.0
Z-Boson Direction
Outgoing Parton
T
Initial-State Radiation
“Transverse”
“Transverse”
“Away”
Z-boson
Z-boson
 CDF data at 1.96 TeV on the density of charged particles, dN/dhd, with pT > 0.5 GeV/c and |h| < 1 for
Drell-Yan production as a function of PT(Z) for the “toward”, “away”, and “transverse” regions compared
with PYTHIA Tune DW.
 CMS data at 7 TeV on the density of charged particles, dN/dhd, with pT > 0.5 GeV/c and |h| < 2 for DrellYan production as a function of PT(Z) for the “toward”, “away”, and “transverse” regions compared with
PYTHIA Tune DW.
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 20
Charged PTsum Density
data corrected
pyDW generator level
data corrected
pyDW generator level
"Toward"
Drell-Yan Production
70 < M(pair) < 110 GeV
1.0
CDF 1.96 TeV
0.5
Charged Particles
(|h|<1.0,
PT>0.5 GeV/c)
Drell-Yan
Production
excluding the lepton-pair
0.1
20
40
60
0
80
20
PT(lepton-pair) GeV/c
Z-Boson Direction

"Transverse"
1.0
"Toward"
CMS
Drell-Yan Production
Charged Particles (PT>0.5 GeV/c)
60 < M(pair) < 120 GeV
High PT Z-Boson Production
0
60
100
40
20
80
40
100
Z-Boson Direction
Outgoing Parton

60
80
100
PT(lepton-pair) GeV/c
PT(lepton-pair) GeV/c
High PT Z-Boson Production
Initial-State Radiation
Outgoing Parton
Initial-State Radiation
“Toward”
“Toward”
Proton
“Transverse”
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
excluding the lepton-pair
0.1
0.0
0
data corrected
pyDW generator level
CMS 7 TeV
"Transverse"
1.0
Charged PTsum Density (GeV/c)
Charged PTsum Density (GeV/c)
10.0
Charged PTsum Density (GeV/c)
Large increase in the UE
inCharged
going from
1.96Density:
TeV dPT/dhd
Charged PTsum Density: dPT/dhd
PTsum
"Toward" Charged PTsum Density: dPT/dhd
to 7 TeV as predicted by
10.0
1.5
CMS Preliminary
CDF Run
2
1.96
TeV DW! "Away"
7 TeV
RDF Preliminary
PYTHIA
Tune
"Away"
Proton
AntiProton
“Transverse”
“Transverse”
“Away”
Proton
“Transverse”
“Away”
Z-boson
Z-boson
 CDF data at 1.96 TeV on the charged PTsum density, dPT/dhd, with pT > 0.5 GeV/c and |h| < 1 for Drell-
Yan production as a function of PT(Z) for the “toward”, “away”, and “transverse” regions compared with
PYTHIA Tune DW.
 CMS data at 7 TeV on the charged PTsum density, dPT/dhd, with pT > 0.5 GeV/c and |h| < 1 for Drell-Yan
production as a function of PT(Z) for the “toward”, “away”, and “transverse” regions compared with
PYTHIA Tune DW.
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 21
PYTHIA Tune DW
Charged Particle Density: dN/dhd
"Toward" Charged Particle Density: dN/dhd
3
1.2
CMS
7 TeV
data corrected
pyDW generator level
"Away"
Drell-Yan Production
60 < M(pair) < 120 GeV
2
Charged Particle Density
Average Charged Density
CMS Preliminary
data corrected
pyDW generator level
CMS 7 TeV
0.8
CDF 1.96 TeV
Overall PYTHIA0.4Tune DW
"Toward"
is in amazingly good agreement
with the
Charged Particles (PT>0.5 GeV/c)
Drell-Yan Production
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
excluding
the
lepton-pair
Tevatron Jet production 0.0
and Drell-Yan data
20
40
60 did a very
80
100 job in
0 predicting
20
60
80
and
good
the40
PT(lepton-pair) GeV/c
PT(lepton-pair) GeV/c
LHC Jet production and Drell-Yan data!
"Transverse" Charged Particle Density: dN/dhd
"Transverse" Charged Particle Density: dN/dhd
(although not perfect)
"Transverse"
1
0
0
100
1.5
1.5
RDF Preliminary
data corrected
pyDW generator level
Charged Particle Density
RDF Preliminary
Charged Particle Density
RDF Preliminary
CMS 7 TeV
1.0
CDF 1.96 TeV
0.5
CMS 900 GeV
CMS 7 TeV
data corrected
pyDW generator level
1.0
CDF 1.96 TeV
0.5
CMS 900 GeV
Charged Particles (PT>0.5 GeV/c)
Charged Particles (PT>0.5 GeV/c)
0.0
0.0
0
20
40
60
80
100
0
100
150
200
250
PT(chgjet#1 or jet#1) GeV/c
PT(chgjet#1 or jet#1) GeV/c
GGI Florence, Italy
September 14, 2011
50
Rick Field – Florida/CDF/CMS
Page 22
300
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 AMBT1 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!
GGI Florence, Italy
September 14, 2011
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 23
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
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 24
CMS UE Data
"Transverse" Charged PTsum Density: dPT/dhd
"Transverse" Charged Particle Density: dN/dhd
2.0
CMS Preliminary
CMS Preliminary
data corrected
Tune Z1 generator level
7 TeV
PTsum Density (GeV/c)
Charged Particle Density
1.6
1.2
0.8
900 GeV
CMS
0.4
Tune Z1
data corrected
Tune Z1 generator level
1.6
7 TeV
1.2
CMS
0.8
900 GeV
Tune Z1
0.4
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
10
20
30
40
50
60
70
80
90
100
0
10
PT(chgjet#1) GeV/c
GGI Florence, Italy
September 14, 2011
30
40
50
60
70
80
90
100
PT(chgjet#1) GeV/c
 CMS preliminary data at 900 GeV and 7
TeV on the “transverse” charged particle
density, dN/dhd, 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 corrected and compared with
PYTHIA Tune Z1 at the generator level.
CMS corrected
data!
20
 CMS preliminary data at 900 GeV and 7
TeV on the “transverse” charged PTsum
density, dPT/dhd, 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 corrected and compared with
PYTHIA Tune Z1 at the generator level.
Very nice agreement!
Rick Field – Florida/CDF/CMS
CMS corrected
data!
Page 25
ATLAS UE Data
"Transverse" Charged PTsum Density: dPT/dhd
"Transverse" Charged Particle Density: dN/dhd
1.5
RDF Preliminary
RDF Preliminary
7 TeV
ATLAS corrected data
Tune Z1 generator level
PTsum Density (GeV/c)
"Transverse" Charged Density
1.2
0.8
ATLAS
900 GeV
0.4
Tune Z1
7 TeV
ATLAS corrected data
Tune Z1 generator level
1.0
ATLAS
900 GeV
0.5
Tune Z1
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
5
10
15
20
25
0
5
10
15
20
25
PTmax (GeV/c)
PTmax (GeV/c)
 ATLAS published data at 900 GeV and 7
TeV on the “transverse” charged particle
density, dN/dhd, 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.
 ATLAS published data at 900 GeV and 7
TeV on the “transverse” charged PTsum
density, dPT/dhd, 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.
ATLAS publication – arXiv:1012.0791
December 3, 2010
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 26
CMS-ATLAS UE Data
"Transverse" Charged Particle Density: dN/dhd
"Transverse" Charged Particle Density: dN/dhd
1.6
RDF Preliminary
RDF Preliminary
CMS: Chgjet#1
data corrected
Tune Z1 generator level
Charged Particle Density
Charged Particle Density
1.6
1.2
0.8
CMS (red)
ATLAS (blue)
ATLAS: PTmax
0.4
Tune Z1
data corrected
Tune Z1 generator level
1.2
0.8
CMS (red)
ATLAS (blue)
Tune Z1
0.4
Charged Particles (PT > 0.5 GeV/c)
7 TeV
Charged Particles (PT > 0.5 GeV/c)
7 TeV
0.0
0.0
0
5
10
15
20
25
30
0
10
20
30
40
50
60
70
80
90
100
PTmax or PT(chgjet#1) (GeV/c)
PTmax or PT(chgjet#1) (GeV/c)
 CMS preliminary data at 7 TeV on the “transverse” charged particle density, dN/dhd, as
defined by the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c
and |h| < 2.0 together with the ATLAS published data at 7 TeV on the “transverse” charged
particle density, dN/dhd, 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.
Amazing agreement!
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 27
Jet Radius Dependence
The UE activity is higher
for large jet radius!
"Transverse" Charged Particle Density: dN/dhd
Charged Particle Density
1.5
d = 1.0
RDF Preliminary
pyZ1 generator level
1.0
d = 0.5
7 TeV
d = 0.2
0.5
Chgjet#1 (|h|<1.5)
Tune Z1
Charged Particles (|h|<2.5, PT>0.5 GeV/c)
0.0
0
10
20
30
40
50
60
70
80
90
100
PT(chgjet#1) GeV/c
 The charged particle density in the “transverse” region as defined by the leading charged
particle jet from PYTHIA Tune Z1. The charged particles are in the region pT > 0.5 GeV/c and
|h| < 2.5. Charged particle jets are constructed using the Anti-KT algorithm with d = 0.2, 0.5,
and 1.0 from charged particles in the region pT > 0.5 GeV/c and |h| < 2.5, however, the leading
charged particle jet is required to have |h(chgjet#1)| < 1.5.
It appears that large jet radius
“biases” the UE to be more active!
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 28
PYTHIA Tune Z1
"Transverse" Charged Particle Density: dN/dhd
2.5
1.5
1.0
0.5
3.0
2.0
0.0
2
4
6
Factor of 2 increase!
8
RDF Preliminary
ATLAS corrected data
Tune Z1 generator level
ATLAS
Charged Particles (|h|<2.5)
7 TeV
RDF Preliminary
2.0
PT > 0.1 GeV/c
generator level
Tune Z1 (solid)
Tune DW (dashed)
Charge Particle1.5
Density
PT > 0.5 GeV/c
Tune Z1
0
"Transverse" PTsum Density
7 TeV
ATLAS corrected data
Tune Z1 generator level
2.0
PT > 0.1 GeV/c
4.0
RDF Preliminary
"Transverse" Ratio 0.1/0.5
"Transverse" Charged Density
"Transverse" Charged PTsum Density: dPT/dhd
"Transverse" Ratio: PT >2.50.1 and > 0.5 GeV/c
1.0
ATLAS
0.5
PT > 0.5 GeV/c
Tune Z1
Charged Particles (|h|<2.5)
0.0
1.0
10
12
PTmax (GeV/c)
14
16
18
Charge PTsum Density
20
0
2
4
76 TeV 8
10
12
14
16
18
20
Charged Particles
(|h|<2.5)
PTmax
(GeV/c)
0.0
 ATLAS preliminary data
at 27 TeV4 on the
 10ATLAS
preliminary
data20at 7 TeV on the
0
6
8
12
14
16
18
“transverse” charged particle density,
“transverse” charged PTsum density,
PTmax (GeV/c)
dN/dhd, as defined by the leading charged
dPT/dhd, as defined by the leading charged
particle (PTmax) for charged particles with
particle (PTmax) for charged particles with
pT > 0.5 GeV/c and |h| < 2.5. The data are
pT > 0.5 GeV/c and |h| < 2.5. The data are
corrected and compared with PYTHIA Tune
corrected and compared with PYTHIA Tune
Z1 at the generator level. Also shows the
Z1 at the generator level. Also shows the
prediction of Tune Z1 for the “transverse”
prediction of Tune Z1 for the “transverse”
charged particle density with pT > 0.1 GeV/c
Rick Fieldcharged particle density with pT > 0.1 GeV/c
and |h| < 2.5.
and |h| < 2.5.
MPI@LHC 2010 Glasgow, Scotland
December 2, 2010
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 29
PYTHIA Tune Z1
"Transverse"Charged
ChargedParticle
Particle Density:
Density: dN/dhd
dN/dhd
"Transverse"
"Transverse"
1.5
1.5
1.0
1.0
Tune Z1
7 TeV
0.0
0.0
00
22
44
2.5
PT > 0.1 GeV/c
7 TeV
ATLAS corrected data
ATLAS corrected data
Tune Z1 generator level
Tune Z1 generator level
0.5
0.5
"Transverse" Charged PTsum Density:
Density: dPT/dhd
dPT/dhd
Ratio: PT > 0.1 "Transverse"
and
> 0.5 GeV/c
66
RDF Preliminary
RDF
Preliminary
ATLAS
ATLAScorrected
correcteddata
data
RDF
Tune
TuneZ1
Z1generator
generatorlevel
level
2.0
PTPT
> 0.1
GeV/c
> 0.5
GeV/c
2.0
ATLAS
Charged
Particles
(|h|<2.5)
Charged
Particles
(|h|<2.5)
7 TeV
Preliminary
ATLAS corrected data
Tune Z1 generator level
Tune Z1
Charge Particle Density
3.0
PT > 0.5 GeV/c
88
PTsum Density
(GeV/c)
"Transverse"
PTsum
Density
2.0
2.0
4.0
RDFPreliminary
Preliminary
RDF
"Transverse" Ratio 0.1/0.5
"Transverse"
Density
"Transverse" Charged
Charged Density
2.5
2.5
1.5
PT > 0.1 GeV/c
PT > 0.1 GeV/c
1.0
ATLAS
PT > 0.5 GeV/c
PT > 0.5 GeV/c
0.5
Charged Particles (|h|<2.5)
Charged Particles (|h|<2.5)
7 TeV
0.0
1.0
10
10
12
12
PTmax (GeV/c)
(GeV/c)
PTmax
14
14
16
16
18
18
20
20
Charge PTsum Density
0
2
4
76 TeV 8
10
12
14
16
18
20
(GeV/c)
(GeV/c)
Charged ParticlesPTmax
(|h|<2.5)
 ATLAS preliminary0.0data at 7 TeV on the
10 ATLAS
preliminary
data20at 7 TeV on the
0
2
4
6
8
12
14
16
18
“transverse” charged particle density,
“transverse” charged PTsum density,
PTmax (GeV/c)
dN/dhd, as defined by the leading charged
dPT/dhd, as defined by the leading charged
particle (PTmax) for charged particles with
particle (PTmax) for charged particles with
pT > 0.5 GeV/c and pT > 0.1 GeV/c (|h| < 2.5).
pT > 0.5 GeV/c and pT > 0.1 GeV/c (|h| < 2.5).
The data are corrected and compared with
The data are corrected and compared with
PYTHIA Tune Z1 at the generator level.
PYTHIA Tune Z1 at the generator level.
ATLAS publication – arXiv:1012.0791
December 3, 2010
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 30
ALICE UE Data
"Transverse" Charged PTsum Density: dPT/dhd
"Transverse" Charged Particle Density: dN/dhd
1.5
RDF Preliminary
RDF Preliminary
7 TeV
ALICE corrected data
Tune Z1 generator level
PTsum Density (GeV/c)
"Transverse" Charged Density
1.2
0.8
900 GeV
0.4
ALICE
Tune Z1
7 TeV
ALICE corrected data
Tune Z1 generator level
1.0
900 GeV
0.5
ALICE
Tune Z1
Charged Particles (|h|<0.8, PT>0.5 GeV/c)
Charged Particles (|h|<0.8, PT>0.5 GeV/c)
0.0
0.0
0
5
10
15
20
25
0
5
 ALICE preliminary data at 900 GeV and 7
TeV on the “transverse” charged particle
density, dN/dhd, as defined by the leading
charged particle (PTmax) for charged
particles with pT > 0.5 GeV/c and |h| < 0.8.
The data are corrected and compared with
PYTHIA Tune Z1 at the generator level.
GGI Florence, Italy
September 14, 2011
15
20
25
PTmax (GeV/c)
PTmax (GeV/c)
I read the points off
with a ruler!
10
 ALICE preliminary data at 900 GeV and 7
TeV on the “transverse” charged PTsum
density, dPT/dhd, as defined by the leading
charged particle (PTmax) for charged
particles with pT > 0.5 GeV/c and |h| < 0.8.
The data are corrected and compared with
PYTHIA Tune Z1 at the generrator level.
ALICE UE Data: Talk by S. Vallero
MPI@LHC 2010 Glasgow, Scotland
November 30, 2010
Rick Field – Florida/CDF/CMS
Page 31
ATLAS UE Data
"Transverse" Charged Particle Density: dN/dhd
1.5
RDF Preliminary
7 TeV
RDF Preliminary
ATLAS corrected data
Tune Z1 generator level
PTsum Density (GeV/c)
"Transverse" Charged Density
1.2
"Transverse" Charged PTsum Density: dPT/dhd
0.8
900 GeV
0.4
ATLAS
Tune Z1
7 TeV
ATLAS corrected data
Tune Z1 generator level
1.0
900 GeV
0.5
ATLAS
Tune Z1
Charged Particles (|h|<0.8, PT>0.5 GeV/c)
0.0
Charged Particles (|h| < 0.8, PT > 0.5 GeV/c)
0.0
0
5
10
15
20
25
0
5
PTmax (GeV/c)
10
15
20
25
PTmax (GeV/c)
 ATLAS preliminary data at 900 GeV and 7
TeV on the “transverse” charged particle
density, dN/dhd, as defined by the leading
charged particle (PTmax) for charged
particles with pT > 0.5 GeV/c and |h| < 0.8.
The data are corrected and compared with
PYTHIA Tune Z1 at the generator level.
 ATLAS preliminary data at 900 GeV and 7
TeV on the “transverse” charged PTsum
density, dPT/dhd, as defined by the leading
charged particle (PTmax) for charged
particles with pT > 0.5 GeV/c and |h| < 0.8.
The data are corrected and compared with
PYTHIA Tune Z1 at the generrator level.
ATLAS-CONF-2011-009
February 21, 2011
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 32
MB&UE Working Group
MB & UE Common Plots
CMS
ATLAS
 The LPCC MB&UE Working Group has suggested
several MB&UE “Common Plots” the all the LHC
groups can produce and compare with each other.
Outgoing Parton
“Minimum Bias” Collisions
PT(hard)
Initial-State Radiation
Proton
Proton
Underlying Event
Outgoing Parton
GGI Florence, Italy
September 14, 2011
Proton
Proton
Underlying Event
Final-State
Radiation
Rick Field – Florida/CDF/CMS
Page 33
ALICE-ATLAS UE
"Transverse" Charged Particle Density: dN/dhd
"Transverse" Charged Particle Density: dN/dhd
1.2
RDF Preliminary
"Transverse" Charged Density
"Transverse" Charged Density
1.2
7 TeV
ALICE corrected data
Tune Z1 generator level
0.8
900 GeV
0.4
ALICE
Tune Z1
Charged Particles (|h|<0.8, PT>0.5 GeV/c)
RDF Preliminary
7 TeV
ATLAS corrected data
Tune Z1 generator level
0.8
900 GeV
0.4
ATLAS
Tune Z1
Charged Particles (|h|<0.8, PT>0.5 GeV/c)
0.0
0.0
0
5
10
15
20
25
0
10
15
20
25
PTmax (GeV/c)
PTmax (GeV/c)
 ALICE preliminary data at 900 GeV and 7
TeV on the “transverse” charged particle
density, dN/dhd, as defined by the leading
charged particle (PTmax) for charged
particles with pT > 0.5 GeV/c and |h| < 0.8.
The data are corrected and compared with
PYTHIA Tune Z1 at the generator level.
GGI Florence, Italy
September 14, 2011
5
 ATLAS preliminary data at 900 GeV and 7
TeV on the “transverse” charged particle
density, dN/dhd, as defined by the leading
charged particle (PTmax) for charged
particles with pT > 0.5 GeV/c and |h| < 0.8.
The data are corrected and compared with
PYTHIA Tune Z1 at the generrator level.
Rick Field – Florida/CDF/CMS
Page 34
ALICE-ATLAS UE
"Transverse" Charged PTsum Density: dPT/dhd
"Transverse" Charged PTsum Density: dPT/dhd
1.5
1.5
RDF Preliminary
7 TeV
ALICE corrected data
Tune Z1 generator level
PTsum Density (GeV/c)
PTsum Density (GeV/c)
RDF Preliminary
1.0
900 GeV
0.5
ALICE
Tune Z1
1.0
900 GeV
0.5
ATLAS
Tune Z1
Charged Particles (|h|<0.8, PT>0.5 GeV/c)
0.0
7 TeV
ATLAS corrected data
Tune Z1 generator level
Charged Particles (|h| < 0.8, PT > 0.5 GeV/c)
0.0
0
5
10
15
20
25
0
PTmax (GeV/c)
10
15
20
25
PTmax (GeV/c)
 ALICE preliminary data at 900 GeV and 7
TeV on the “transverse” charged particle
density, dN/dhd, as defined by the leading
charged particle (PTmax) for charged
particles with pT > 0.5 GeV/c and |h| < 0.8.
The data are corrected and compared with
PYTHIA Tune Z1 at the generator level.
GGI Florence, Italy
September 14, 2011
5
 ATLAS preliminary data at 900 GeV and 7
TeV on the “transverse” charged particle
density, dN/dhd, as defined by the leading
charged particle (PTmax) for charged
particles with pT > 0.5 GeV/c and |h| < 0.8.
The data are corrected and compared with
PYTHIA Tune Z1 at the generrator level.
Rick Field – Florida/CDF/CMS
Page 35
Tevatron Energy Scan
Proton
CDF
1 mile
AntiProton
Proton
900GeV
GeV
300
1.96
TeV
AntiProton
 Over the past few days CDF has collected
more than 10M “min-bias” events at
several center-of-mass energies!
300 GeV 12M MB Events
900 GeV 17M MB Events
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 36
PYTHIA Tune Z1
"Transverse"Charged
ChargedParticle
ParticleDensity:
Density:dN/dhd
dN/dhd
"Transverse"
1.2
"Transverse" Charged Particle Density: dN/dhd
1.5
CMSPreliminary
Preliminary
RDF
RDF Preliminary
data
corrected
data
corrected
Tune generator
Z1 generator
level
pyZ1
level
CMS 7 TeV7 TeV
Charged Particle Density
Charged
Charged Particle
Particle Density
Density
1.6
1.5
1.0
CDF 1.96 TeV
0.8
900 GeV
0.5
0.4
CMS 900 GeV
Tune Z1
data corrected
pyZ1 generator level
CMS 7 TeV
1.0
CDF 1.96 TeV
0.5
CMS 900 GeV
Tune Z1
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
Charged Particles (PT>0.5 GeV/c)
0.0
0.0
Charged Particles (PT>0.5 GeV/c)
0.0
00
10
20
20
30
40
40
50
60
60
70
80
80
90
100
100
0
50
PT(chgjet#1)
GeV/c
PT(chgjet#1
or jet#1)
GeV/c
100
150
200
250
300
PT(chgjet#1 or jet#1) GeV/c
 CMS data at 900 GeV on the “transverse”
 CDF data at 1.96 TeV on the “transverse”
charged particle density, dN/dhd, as
charged particle density, dN/dhd, as
defined by the leading charged particle jet
defined by the leading calorimeter jet (jet#1)
(chgjet#1) for charged particles with pT >
for charged particles with pT > 0.5 GeV/c
0.5 GeV/c and |h| < 2.0. The data are
and |h| < 1.0. The data are corrected and
corrected and compared with PYTHIA Tune
compared with PYTHIA Tune Z1 at the
Z1 at the generator level.
generator level.
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 37
PYTHIA Tune Z1
"Transverse" Charged PTsum Density: dPT/dhd
"Transverse" Charged PTsum Density: dPT/dhd
2.0
2.0
RDF Preliminary
datacorrected
corrected
data
Tune
generator
level
pyZ1 Z1
generator
level
1.6
7 TeV
CMS
7 TeV
1.2
PTsum Density (GeV/c)
PTsum Density (GeV/c)
CMSPreliminary
Preliminary
RDF
CDF 1.96 TeV
0.8
900 GeV
CMS 900 GeV
Tune Z1
0.4
CMS 7 TeV
data corrected
pyZ1 generator level
1.6
CDF 1.96 TeV
1.2
0.8
Tune Z1
CMS 900 GeV
0.4
Charged Particles (PT>0.5 GeV/c)
Charged Particles (PT>0.5 GeV/c)
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
0.0
0
10
20
30
40
50
60
70
80
90
100
0
100
150
200
250
300
PT(chgjet#1 or jet#1) GeV/c
PT(chgjet#1
or jet#1)
GeV/c
PT(chgjet#1)
GeV/c
 CMS data at 900 GeV and 7 TeV on the
“transverse” charged PTsum density,
dPT/dhd, 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 corrected and compared with PYTHIA
Tune Z1 at the generator level.
GGI Florence, Italy
September 14, 2011
50
 CDF data at 1.96 TeV on the “transverse”
charged PTsum density, dPT/dhd, 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 Z1 at the
generator level.
Rick Field – Florida/CDF/CMS
Page 38
PYTHIA Tune Z1
Tune Z1 describes the
energy dependence
Charged Particle Density: dN/dhd
Charged Particle Density: dN/dhd
"Toward" Charged Particle Density: dN/dhd
fairly well!
3
1.2
Drell-Yan Production
70 < M(pair) < 110 GeV
2
1
CMS Preliminary
RDF Preliminary
1.96 TeV
data corrected
pyZ1 generator level
Charged Particle Density
Average Charged Density
CDF Run 2
Average Charged Density
3
data corrected
"Away"
pyZ1 generator level
0.8
Charged Particles
(|h|<1.0, Production
PT>0.5 GeV/c)
Drell-Yan
excluding the lepton-pair
0
10
20
30
40
50
60
0
70
80
20
PT(lepton-pair) GeV/c
Z-Boson Direction

High PT Z-Boson Production
90
"Transverse"
1
"Toward"
0
100
40
0 60
2080
40
100
Z-Boson Direction

High PT Z-Boson Production
Initial-State Radiation
80
100
Outgoing Parton
Initial-State Radiation
“Toward”
“Toward”
Proton
“Transverse”
60
PT(lepton-pair) GeV/c
PT(lepton-pair) GeV/c
Outgoing Parton
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
excluding the lepton-pair
Charged Particles (PT>0.5 GeV/c)
0.0
0
"Away"
Drell-Yan Production
60 < M(pair) < 120 GeV
2
CDF 1.96 TeV
0.4
"Transverse"
"Toward"
CMS
7 TeV
data corrected
pyZ1
generator level
CMS 7
TeV
Proton
AntiProton
“Transverse”
“Transverse”
“Away”
Proton
“Transverse”
“Away”
Z-boson
Z-boson
 CDF data at 1.96 TeV on the density of charged particles, dN/dhd, with pT > 0.5 GeV/c and |h| < 1 for
Drell-Yan production as a function of PT(Z) for the “toward”, “away”, and “transverse” regions compared
with PYTHIA Tune Z1.
 CMS data at 7 TeV on the density of charged particles, dN/dhd, with pT > 0.5 GeV/c and |h| < 2 for DrellYan production as a function of PT(Z) for the “toward”, “away”, and “transverse” regions compared with
PYTHIA Tune Z1.
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 39
PYTHIA Tune Z1
Charged PTsum Density: dPT/dhd
Charged PTsum Density: dPT/dhd
"Toward" Charged PTsum Density: dPT/dhd
10.0
1.5
1.96 TeV
data corrected
pyZ1 generator level
"Away"
RDF
Preliminary
data corrected
pyZ1 generator level
"Toward"
Drell-Yan Production
70 < M(pair) < 110 GeV
1.0
CDF 1.96 TeV
0.5
Charged Particles
(|h|<1.0,
PT>0.5 GeV/c)
Drell-Yan
Production
excluding the lepton-pair
0.1
20
40
60
0
80
20
PT(lepton-pair) GeV/c
Z-Boson Direction

7 TeV
"Transverse"
1.0
"Toward"
Drell-Yan Production
Charged Particles (PT>0.5 GeV/c)
60 < M(pair) < 120 GeV
High PT Z-Boson Production
100
40
0
60
20
80
CMS
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
excluding the lepton-pair
40
100
Z-Boson Direction
Outgoing Parton

60
80
100
PT(lepton-pair) GeV/c
PT(lepton-pair) GeV/c
High PT Z-Boson Production
Initial-State Radiation
Outgoing Parton
Initial-State Radiation
“Toward”
“Toward”
Proton
“Transverse”
"Away"
data corrected
pyZ1 generator level
0.1
0.0
0
CMS Preliminary
CMS 7 TeV
"Transverse"
1.0
Charged PTsum Density (GeV/c)
CDF Run 2
Charged PTsum Density (GeV/c)
Charged PTsum Density (GeV/c)
10.0
Proton
AntiProton
“Transverse”
“Transverse”
“Away”
Proton
“Transverse”
“Away”
Z-boson
Z-boson
 CDF data at 1.96 TeV on the charged PTsum density, dPT/dhd, with pT > 0.5 GeV/c and |h| < 1 for Drell-
Yan production as a function of PT(Z) for the “toward”, “away”, and “transverse” regions compared with
PYTHIA Tune Z1.
 CMS data at 7 TeV on the charged PTsum density, dPT/dhd, with pT > 0.5 GeV/c and |h| < 2 for Drell-Yan
production as a function of PT(Z) for the “toward”, “away”, and “transverse” regions compared with
PYTHIA Tune Z1.
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 40
PYTHIA Tune Z1
"Transverse" Charged Particle Density: dN/dhd
"Transverse" Charged Particle Density: dN/dhd
1.2
1.5
RDF Preliminary
data corrected
pyZ1 generator level
Charged Particle Density
Charged Particle Density
RDF Preliminary
CMS 7 TeV
1.0
CDF 1.96 TeV
0.5
CMS 900 GeV
Tune Z1
0.8
CDF 1.96 TeV
0.4
Tune Z1
0.0
0
20
40
60
80
100
0
20
PT(chgjet#1 or jet#1) GeV/c
3.0
7 TeV
1.2
0.8
Drell-Yan Production
0.4
80
100
RDF Preliminary
Chgjet Production
Charged Particle Density
data corrected
pyZ1 generator level
60
"Away" Charged Particle Density: dN/dhd
1.6
CMS Preliminary
40
PT(lepton-pair) GeV/c
"Transverse" Charged Particle Density: dN/dhd
Charged Particle Density
Charged Particles (PT>0.5 GeV/c)
Drell-Yan Production
Charged Particles (PT>0.5 GeV/c)
0.0
CMS 7 TeV
data corrected
pyZ1 generator level
Tune Z1
data corrected
pyZ1 generator level
CDF 1.96 TeV
2.0
CMS 7 TeV
1.0
Tune Z1
Drell-Yan Production
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
Charged Particles (PT>0.5 GeV/c)
0.0
0.0
0
10
20
30
40
50
60
70
80
90
100
0
40
60
80
100
PT(lepton-pair) GeV/c
PT(chgjet#1) or PT(lepton-pair) GeV/c
GGI Florence, Italy
September 14, 2011
20
Rick Field – Florida/CDF/CMS
Page 41
PYTHIA Tune Z1
"Transverse" Charged PTsum Density: dPT/dhd
"Transverse" Charged PTsum Density: dPT/dhd
2.0
Charged PTsum Density (GeV/c)
2.0
PTsum Density (GeV/c)
RDF Preliminary
data corrected
pyZ1 generator level
1.6
CMS 7 TeV
1.2
CDF 1.96 TeV
0.8
CMS 900 GeV
0.4
Tune Z1
Charged PTsum Density (GeV/c)
2.0
1.5
CMS 7 TeV
1.0
CDF 1.96 TeV
0.5
Charged Particles (PT>0.5 GeV/c)
90
100
10.0
CMS Preliminary
7 TeV
data corrected
pyZ1 generator level
RDF Preliminary
What about Min-Bias?
Chgjet Production
Charged PTsum Density (GeV/c)
0
Tune Z1
data corrected
pyZ1 generator level
Drell-Yan Production
Overall amazingly good agreement
0.0
with
0
10
20
30
40
50
60
70
80
10
20
30
40
50
60
70
80the90LHC
100 and Tevatron
PT(chgjet#1 or jet#1) GeV/c
Jet production and Drell-Yan! PT(lepton-pair) GeV/c
not perfect yet)
"Away" Charged PTsum Density: dPT/dhd
"Transverse" Charged PTsum Density:(although
dPT/dhd
Charged Particles (PT>0.5 GeV/c)
0.0
RDF Preliminary
1.5
1.0
Tune Z1
0.5
Drell-Yan Production
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
data corrected
pyZ1 generator level
8.0
CDF 1.96 TeV
Drell-Yan Production
6.0
CMS 7 TeV
4.0
Tune Z1
2.0
Charged Particles (PT>0.5 GeV/c)
0.0
0.0
0
10
20
30
40
50
60
70
80
90
100
0
10
30
40
50
60
70
80
90
PT(lepton-pair) GeV/c
PT(chgjet#1) or PT(lepton-pair) GeV/c
GGI Florence, Italy
September 14, 2011
20
Rick Field – Florida/CDF/CMS
Page 42
100
The Inelastic Non-Diffractive
Cross-Section
Occasionally one of
the parton-parton
collisions is hard
(pT > ≈2 GeV/c)
Proton
Proton
Majority of “minbias” events!
Proton
“Semi-hard” partonparton collision
(pT < ≈2 GeV/c)
Proton
+
Proton
+
Proton
Proton
Proton
+
Proton
Proton
+…
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Multiple-parton
interactions (MPI)!
Page 43
The “Underlying Event”
Select inelastic non-diffractive events
that contain a hard scattering
Proton
Hard parton-parton
collisions is hard
(pT > ≈2 GeV/c)
Proton
1/(pT)4→ 1/(pT2+pT02)2
The “underlying-event” (UE)!
Proton
Given that you have one hard
scattering it is more probable to
have MPI! Hence, the UE has
more activity than “min-bias”.
GGI Florence, Italy
September 14, 2011
Proton
+
+
Proton
Proton
Rick Field – Florida/CDF/CMS
“Semi-hard” partonparton collision
(pT < ≈2 GeV/c)
Proton
Proton
+…
Multiple-parton
interactions (MPI)!
Page 44
Allow leading hard
scattering to go to
zero pT with same
cut-off as the MPI!
Model of sND
Proton
Proton
Proton
Proton
Proton
+
Proton
“Semi-hard” partonparton collision
(pT < ≈2 GeV/c)
1/(pT)4→ 1/(pT2+pT02)2
Model of the inelastic nondiffractive cross section!
+
Proton
Proton
Proton
+
Proton
Proton
+…
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Multiple-parton
interactions (MPI)!
Page 45
UE Tunes
Allow primary hard-scattering to
go to pT = 0 with same cut-off!
“Underlying Event”
Fit the “underlying
event” in a hard
scattering process.
Proton
Proton
1/(pT)4→ 1/(pT2+pT02)2
“Min-Bias”
“Min-Bias” (add
(ND)single & double diffraction)
Proton
Predict MB (ND)!
Proton
+
+
Proton
Proton
Proton
Single Diffraction
Predict MB (IN)!
GGI Florence, Italy
September 14, 2011
+…
Proton
+
Proton
Proton
Double Diffraction
M2
M
Rick Field – Florida/CDF/CMS
M1
Page 46
LHC MB Predictions: 900 GeV
Charged Particle Density: dN/dh
Charged Particle Density: dN/dh
5
5
RDF Preliminary
Charged Particle Density
Charged Particle Density
RDF Preliminary
4
3
2
ALICE INEL
Off by 11%!
UA5 INEL
INEL = HC+DD+SD
900 GeV
1
5
-1.5
-1.0
-0.5
0.0
4
Charged Particle Density
-2.0
2
UA5
ALICE
1
pyDW_10mm (3.04)
pyS320_10mm (3.09)
pyS320 INEL (2.70)
0
-2.5
3
NSD = HC+DD
Charged Particle Density: dN/dh
900 GeV
pyDW INEL (2.67)
Charged Particles (all pT)
-3.0
4
RDF Preliminary
0.5
1.0
1.5
0
2.0
2.5
3.0
-3.0
-2.5
-2.0 times
-1.5 1.11
-1.0
3
0.5
1.0
1.5
2.0
2.5
“Minimum Bias” Collisions
“Minimum Bias” Collisions
2
Proton
1
0.0
PseudoRapidity h
PseudoRapidity h
Proton
-0.5
INEL = HC+DD+SD
900 GeV
Charged Particles (all pT)
Proton
ALICE INEL
UA5 INEL
pyDW times 1.11 (2.97)
pyS320 times 1.11 (3.00)
Proton
0
-3.0 -2.5
-2.0 -1.5 data
-1.0 -0.5
0.0 PYTHIA
0.5
1.0
1.5 Tune
2.0
2.5
3.0 and Tune S320
 Compares the 900 GeV
ALICE
with
DW
PseudoRapidity
h
Perugia 0. Tune DW uses the old Q2-ordered parton shower and the old MPI
model. Tune S320 uses the new pT-ordered parton shower and the new MPI
model. The numbers in parentheses are the average value of dN/dh for the region
|h| < 0.6.
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 47
3.0
PYTHIA Tune DW
If one increases the pT
the agreement
improves!
Charged Particle Density: dN/dh
5
Charged Particle Density
RDF Preliminary
4
At Least 1 Charged Particle |h| < 0.8
900 GeV
ALICE INEL data
pyDW generator level
pT > 0.15 GeV/c
Tune DW
3
pT > 0.5 GeV/c
2
pT > 1.0 GeV/c
1
0
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
PseudoRapidity h
 ALICE inelastic data at 900 GeV on the dN/dh distribution for charged particles (pT >
PTmin) for events with at least one charged particle with pT > PTmin and |h| < 0.8 for
PTmin = 0.15 GeV/c, 0.5 GeV/c, and 1.0 GeV/c compared with PYTHIA Tune DW at the
generator level.
“Minimum Bias” Collisions
ProtonThe
same thing occurs at 7 TeV!
Proton
ALICE, ATLAS, and CMS data coming soon.
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 48
PYTHIA Tune DW
Diffraction
contributes less at
harder scales!
Charged Particle Density: dN/dh
5
Charged Particle Density
RDF Preliminary
4
At Least 1 Charged Particle |h| < 0.8
900 GeV
ALICE INEL data
pyDW generator level
pT > 0.15 GeV/c
3
Tune DW
pT > 0.5 GeV/c
2
pT > 1.0 GeV/c
1
dashed = ND solid = INEL
0
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
PseudoRapidity h
 ALICE inelastic data at 900 GeV on the dN/dh distribution for charged particles (pT >
PTmin) for events with at least one charged particle with pT > PTmin and |h| < 0.8 for
PTmin = 0.15 GeV/c, 0.5 GeV/c, and 1.0 GeV/c compared with PYTHIA Tune Z1 at the
generator level (dashed = ND, solid = INEL).
“Minimum Bias” Collisions
Proton
Cannot
trust PYTHIA 6.2 modeling of diffraction!
Proton
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 49
CMS dN/dh
Charged Particle Density: dN/dh
8
CMS
Charged Particle Density
7 TeV
6
4
RDF Preliminary
2
Tune DW
CMS NSD data
pyDW generator level
All pT
dashed = ND solid = NSD
0
-3.0
-2.5
-2.0
-1.5
-1.0
Soft particles!
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
PseudoRapidity h
 Generator level dN/dh (all pT). Shows the NSD = HC + DD and the HC = ND
contributions for Tune DW. Also shows the CMS NSD data.
“Minimum Bias” Collisions
Proton
GGI Florence, Italy
September 14, 2011
Off by 30%!
Rick Field – Florida/CDF/CMS
Proton
Page 50
Min-Bias Collisions
Charged Particle Density: dN/dh
Charged Particle Density: dN/dh
6
CMS Data
ALICE Data
PYTHIA Tune Z1
PYTHIA Tune Z1
Charged Particle Density
Charged Particle Density
8
6
NSD = ND + DD
4
Tune Z1
CMS
2
pyZ1 ND = dashed
pyZ1 NSD = solid
7 TeV
NSD (all pT)
4
2
Tune Z1
INEL (all pT)
0
ALICE
INEL = NSD + SD
pyZ1 NSD = dashed
pyZ1 INEL = solid
900 GeV
0
-4
-3
-2
-1
0
1
2
3
4
-4
-3
Pseudo-Rapidity h
-2
-1
0
1
2
3
Pseudo-Rapidity h
 CMS NSD data on the charged particle
rapidity distribution at 7 TeV compared
with PYTHIA Tune Z1. The plot shows
the average number of particles per NSD
collision per unit h, (1/NNSD) dN/dh.
 ALICE NSD data on the charged particle
rapidity distribution at 900 GeV compared
with PYTHIA Tune Z1. The plot shows
the average number of particles per INEL
collision per unit h, (1/NINEL) dN/dh.
“Minimum Bias” Collisions
Okay not perfect, but remember
Proton
we know that SD and DD are not modeled well!
Proton
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 51
4
PYTHIA Tune Z1
Charged Particle Density: dN/dh
5
Charged Particle Density
RDF Preliminary
4
ALICE INEL data
pyZ1 generator level
At Least 1 Charged Particle |h| < 0.8
900 GeV
pT > 0.15 GeV/c
3
pT > 0.5 GeV/c
2
pT > 1.0 GeV/c
1
0
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
PseudoRapidity h
 ALICE inelastic data at 900 GeV on the dN/dh distribution for charged particles (pT >
PTmin) for events with at least one charged particle with pT > PTmin and |h| < 0.8 for
PTmin = 0.15 GeV/c, 0.5 GeV/c, and 1.0 GeV/c compared with PYTHIA Tune Z1 at the
generator level.
“Minumum Bias” Collisions
Okay
not perfect, but remember
Proton
Proton
we do not know if the SD & DD are correct!
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 52
MB versus UE
Divide be 2p
Charged Particle Density: dN/dhd
Charged Particle Density: dN/dh
2.5
CMS Data
CMS Data
PYTHIA Tune Z1
PYTHIA Tune Z1
Charged Particle Density
Charged Particle Density
8
6
NSD = ND + DD
4
Tune Z1
CMS
2
pyZ1 ND = dashed
pyZ1 NSD = solid
7 TeV
NSD (all pT)
2.0
1.5
1.0
0.5
pyZ1 ND = dashed
7 TeV
NSD (all pT)
pyZ1 NSD = solid
0.0
0
-4
-3
-2
-1
0
1
2
3
4
-4
-3
-2
-1
0
1
2
3
4
Pseudo-Rapidity h
Pseudo-Rapidity h
 CMS NSD data on the charged particle
 CMS NSD data on the charged particle rapidity
rapidity distribution at 7 TeV compared
distribution at 7 TeV compared with PYTHIA
with PYTHIA Tune Z1. The plot shows
Tune Z1. The plot shows the average number of
the average number of charged particles
charged particles per NSD collision per unit h,
per NSD collision per unit h, (1/NNSD)
(1/NNSD) dN/dhd.
dN/dh.
“Minimum Bias” Collisions
Proton
GGI Florence, Italy
September 14, 2011
Proton
Rick Field – Florida/CDF/CMS
Page 53
MB versus UE
Charged Particle Density: dN/dhd
Transverse Charged Particle Density: dN/dhd
2.5
RDF Preliminary
CMS Data
PYTHIA Tune Z1
PYTHIA Tune Z1
Charged Particle Density
Charged Particle Density
2.5
2.0
Factor of 2!
1.5
1.0
Charged Particles (|h| < 2, all pT)
0.5
Tune Z1
CMS
2.0
Tune Z1
NSD = ND + DD
1.5
1.0
0.5
7 TeV ND
pyZ1 ND = dashed
7 TeV
NSD (all pT)
pyZ1 NSD = solid
0.0
0.0
0
5
10
15
20
25
-4
-3
-2
-1
0
1
2
3
Pseudo-Rapidity h
PT max (GeV/c)
 Shows the density of charged particles in
the “transverse” region as a function of
PTmax for charged particles (All pT, |h| <
2) at 7 TeV from PYTHIA Tune Z1.
Outgoing Parton
 CMS NSD data on the charged particle rapidity
distribution at 7 TeV compared with PYTHIA
Tune Z1. The plot shows the average number of
charged particles per NSD collision per unit h,
(1/NNSD) dN/dhd.
“Minimum Bias” Collisions
PT(hard)
Initial-State Radiation
Proton
Proton
Underlying Event
Outgoing Parton
GGI Florence, Italy
September 14, 2011
4
Proton
Underlying Event
Proton
Final-State
Radiation
Rick Field – Florida/CDF/CMS
Page 54
MB versus UE
Charged Particle Density: dN/dhd
"Transverse" Charged Particle Density: dN/dhd
2.5
CMS Data
ATLAS
2.0
Charged Particle Density
"Transverse" Charged Density
2.5
Factor of 2!
1.5
RDF Preliminary
1.0
ATLAS corrected data
Tune Z1 generator level
0.5
7 TeV
Charged Particles (pT > 0.1 GeV/c, |h|<2.5)
CMS
PYTHIA Tune Z1
2.0
Tune Z1
1.0
0.5
pyZ1 ND = dashed
7 TeV
NSD (all pT)
0.0
NSD = ND + DD
1.5
pyZ1 NSD = solid
0.0
0
2
4
6
8
10
12
14
16
18
20
-4
-3
PTmax (GeV/c)
-2
-1
0
1
2
3
Pseudo-Rapidity h
 ATLAS data on the density of charged
particles in the “transverse” region as a
function of PTmax for charged particles
(pT > 0.1 GeV/c, |h| < 2.5) at 7 TeV
compared with PYTHIA Tune Z1.
Outgoing Parton
 CMS NSD data on the charged particle rapidity
distribution at 7 TeV compared with PYTHIA
Tune Z1. The plot shows the average number of
charged particles per NSD collision per unit h,
(1/NNSD) dN/dhd.
“Minimum Bias” Collisions
PT(hard)
Initial-State Radiation
Proton
Proton
Underlying Event
Outgoing Parton
GGI Florence, Italy
September 14, 2011
4
Proton
Underlying Event
Proton
Final-State
Radiation
Rick Field – Florida/CDF/CMS
Page 55
NSD Multiplicity Distribution
Charged Multiplicity Distribution
1.0E-01
RDF Preliminary
data CMS NSD
pyZ1 generator level
Difficult to produce
enough events with
large multiplicity!
CMS
Probability
1.0E-02
7 TeV
900 GeV
1.0E-03
Charged Particles
(all PT, |h|<2.0)
Tune Z1
1.0E-04
0
20
40
60
80
100
Number of Charged Particles
 Generator level charged multiplicity distribution (all pT, |h| < 2) at 900 GeV and 7
TeV. Shows the NSD = HC + DD prediction for Tune Z1. Also shows the CMS
NSD data.
“Minumum Bias” Collisions
Proton
GGI Florence, Italy
September 14, 2011
Okay not perfect!
But not that bad!
Rick Field – Florida/CDF/CMS
Proton
Page 56
MB & UE
"Transverse" Charged Particle Multiplicity
Charged Multiplicity Distribution
1.0E+00
1.0E-01
“Min-Bias”
RDF Preliminary
“Underlying Event”
data CMS NSD
pyZ1 generator level
Data Corrected
Tune Z1 generator level
1.0E-01
CMS
PT(chgjet#1) > 3 GeV/c
Probability
Probability
1.0E-02
7 TeV
900 GeV
1.0E-03
1.0E-02
900 GeV
1.0E-04
0
20
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
1.0E-05
100
 Generator level charged multiplicity
distribution (all pT, |h| < 2) at 900 GeV
and 7 TeV. Shows the NSD = HC + DD
prediction for Tune Z1. Also shows the
CMS NSD data.
GGI Florence, Italy
September 14, 2011
CMS
Tune Z1
Tune Z1
Difficult to produce
40
60
80
enough
events
with
Number of Charged Particles
large multiplicity!
7 TeV
1.0E-03
1.0E-04
Charged Particles
(all PT, |h|<2.0)
CMS Preliminary
0
5
10
15
20
25
30
35
Number of Charged Particles
Difficult to produce
 CMS corrected data at 900 GeV and 7 TeV
enough events with
on the charged particle multiplicity
large “transverse”
distribution in the “transverse” region for
multiplicity at low
charged particles (pT > 0.5 GeV/c, |h| < 2)
hard scale!
as defined by the leading charged particle
jet with PT(chgjet#1) > 3 GeV/c compared
with PYTHIA Tune Z1 at the generator
level.
Rick Field – Florida/CDF/CMS
Page 57
How Universal are the Tunes?
 Do we need a separate tune for each center-of-mass energy?
Outgoing Parton
PT(hard)
900 GeV, 1.96 TeV, 7 TeV, etc.
Initial-State Radiation
Proton
PYTHIA Tune DW did a nice (although not perfect)
job predicting the LHC Jet Production and Drell-Yan
UE data. I am still hoping for a single tune that will
describe all energies!
Proton
Underlying Event
Underlying Event
Outgoing Parton
Final-State
Radiation
Outgoing Parton
PT(hard)
Initial-State Radiation
Proton
 Do we need a separate tune for each hard QCD
Proton
Underlying Event
Underlying Event
subprocess? Jet Production, Drell-Yan Production, etc.
Outgoing Parton
The same tune can describe both Jet Production and Drell-Yan!
 Do we need separate tunes for “Min-Bias” (MB) and the
Proton
Final-State
Radiation
Color
“Minimum Bias” Collisions
Proton
Connections
“underlying event” (UE) in a hard scattering process?
PHTHIA Tune Z1 does fairly well at both the UE and MB,
but you cannot expect such a naïve approach to be perfect!
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Diffraction
Page 58
Kaon Production
Kshort Rapidity Distribution: dN/dY
Kshort Rapidity Distribution: dN/dY
0.5
0.4
CMS
CMS Data
PYTHIA Tune Z1
0.4
CMS & ALICE Data
INEL = NSD + SD
PYTHIA Tune Z1
7 TeV
0.3
dN/dY
dN/dY
CMS NSD
0.3
0.2
900 GeV
900 GeV
0.2
0.1
0.1
ALICE INEL
Tune Z1
NSD (all pT)
0.0
pyZ1 NSD = solid
Tune Z1
pyZ1 INEL = dashed
0.0
-4
-3
-2
-1
0
1
2
3
4
-4
-3
Rapidity Y
-2
-1
0
1
2
3
Rapidity Y

 CMS NSD data on the Kshort rapidity
distribution at 7 TeV and 900 GeV compared
with PYTHIA Tune Z1. The plot shows the
average number of Kshort per NSD collision per
unit Y, (1/NNSD) dN/dY.
CMS NSD data on the Kshort rapidity
distribution at 900 GeV and the ALICE point at
Y = 0 (INEL) compared with PYTHIA Tune Z1.
The ALICE point is the average number of Kshort
per INEL collision per unit Y at Y = 0, (1/NINEL)
dN/dY.
“Minimum Bias” Collisions
Kshort
Kshort
d s +d s
GGI Florence, Italy
September 14, 2011
4
Proton shortage of Kaons in PYTHIA
Proton Tune Z1!
No overall
Rick Field – Florida/CDF/CMS
d s +d s
Page 59
Kaon Production
Charged Kaons Rapidity: dN/dY
Rapidity Distribution Ratio: Kaons/Pions
Rapidity Distribution Ratio: Kshort/Kaons
0.3
0.8
0.6
ALICE Data
ALICE Data
ALICE
dN/dY
0.4
0.2
PYTHIA Tune Z1
ALICE Data
-
Kshort/(K++K-)
(K +K )
0.6
0.4
0.2
0.2
0.1
pyZ1 NSD = dashed
GeV
TuneINEL
Z1(all pT)
pyZ1 INEL900
= solid
900 GeV
INEL (all pT)
0.0
INEL (all pT)
-3
-2
-1
0
Tune Z1
900 GeV
0.0
0.0
-4
(K++K-)/(p++p-)
ALICE
PYTHIA Tune Z1
dN/dY Particle Ratio
dN/dY Particle Ratio
PYTHIA Tune Z1
+
-4 1
-3 2
-2 3
-1 4
Rapidity Y
0
-4
1
-3 2
Rapidity Y
 ALICE INEL data on the charged kaon
rapidity distribution at 900 GeV compared
with PYTHIA Tune Z1. The plot shows
the average number of charged kaons per
INEL collision per unit Y at Y = 0,
(1/NINEL) dN/dY.
-2 3
-1 4
0
1
2
3
Rapidity Y
 ALICE INEL data on the charged kaon to
charged pion rapidity ratio at 900 GeV
compared with PYTHIA Tune Z1.
“Minimum Bias” Collisions
+
K
u s
K-
Protonshortage of Kaons in PYTHIA
ProtonTune Z1!
No overall
u s
GGI Florence, Italy
September 14, 2011
4
Rick Field – Florida/CDF/CMS
Page 60
Particle Ratios versus PT
PT Particle Ratio: Kaons/Pions
Rapidity Distribution Ratio: Kaons/Pions
0.60
0.3
ALICE Data
+
+
-
ALICE Data
(K +K )/(p +p )
PYTHIA Tune Z1 & Z1C
(K++K-)/(p++p-)
PYTHIA Tune Z1 & Z1C
0.40
dN/dY Particle Ratio
PT Particle Ratio
-
Z1C
Z1
0.20
Tune Z1C
qq/q: 0.1 -> 0.12
us/s: 0.4 -> 0.8
900 GeV
INEL (|Y| < 0.75)
0.2
Z1C
0.1
900 GeV
INEL (all pT)
0.00
Z1
Tune Z1C
qq/q: 0.1 -> 0.12
us/s: 0.4 -> 0.8
0.0
0
1
2
PT (GeV/c)
3
4
-3
-2
-1
Tails of the pT distribution.
Way off due to the wrong pT!
 ALICE INEL data on the charged kaons to
charged pions ratio versus pT at 900 GeV (|Y|
< 0.75) compared with PYTHIA Tune Z1 &
Z1C.
0
1
2
3
K-
 ALICE INEL data on the charged kaon to
charged pion rapidity ratio at 900 GeV
compared with PYTHIA Tune Z1.
PYTHIA pT dependence off onProton
Kaons!
Proton
u s
GGI Florence, Italy
September 14, 2011
4
Rapidity Y
“Minimum Bias” Collisions
K+
u s
-4
Rick Field – Florida/CDF/CMS
Page 61
PYTHIA 6.4.25
Tune Z1
Tune Z2
Tune S350
Tune S356
GGI Florence, Italy
September 14, 2011
--------------------------------------------------------------------4th generation: tunes incorporating 7-TeV data
PYTUNE
--------------------------------------------------------------------340 AMBT1
: 1st ATLAS tune incl 7 TeV, w. LO* PDFs
(2010)
341 Z1
: Retune of AMBT1 by Field w CTEQ5L PDFs
(2010)
342 Z1-LEP : Retune of Z1 by Skands w CTEQ5L PDFs
(2010)
343 Z2
: Retune of Z1 by Field w CTEQ6L1 PDFs
(2010)
344 Z2-LEP : Retune of Z1 by Skands w CTEQ6L1 PDFs
(2010)
350 Perugia 2011 : Retune of Perugia 2010 incl 7-TeV data (Mar 2011)
351 P2011 radHi : Variation with alphaS(pT/2)
352 P2011 radLo : Variation with alphaS(2pT)
353 P2011 mpiHi : Variation with more semi-hard MPI
354 P2011 noCR : Variation without color reconnections
355 P2011 LO** : Perugia 2011 using MSTW LO** PDFs
(Mar 2011)
356 P2011 C6 : Perugia 2011 using CTEQ6L1 PDFs
(Mar 2011)
357 P2011 T16 : Variation with PARP(90)=0.16 away from 7 TeV
358 P2011 T32 : Variation with PARP(90)=0.32 awat from 7 TeV
359 P2011 TeV : Perugia 2011 optimized for Tevatron (Mar 2011)
360 S Global : Schulz-Skands Global fit
(Mar 2011)
361 S 7000
: Schulz-Skands at 7000 GeV
(Mar 2011)
362 S 1960 : Schulz-Skands at 1960 GeV
(Mar 2011)
363 S 1800
: Schulz-Skands at 1800 GeV
(Mar 2011)
364 S 900
: Schulz-Skands at 900 GeV
(Mar 2011)
365 S 630
: Schulz-Skands at 630 GeV
(Mar 2011)
=========================================================
Rick Field – Florida/CDF/CMS
CTEQ5L
CTEQ6L
CTEQ5L
CTEQ6L
Page 62
LEP: Kshort Spectrum
S350 Perugia 2011
Rapidity Distribution Ratio: Kaons/Pions
0.3
dN/dY Particle Ratio
ALICE Data
+
-
+
-
(K +K )/(p +p )
PYTHIA Tune Z1 & S350
0.2
Theory/Data
0.1
pyZ1 = solid
pyS350 = dashed
900 GeV
INEL (all pT)
0.0
-4
-3
-2
-1
0
1
2
3
4
Rapidity Y
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 63
Lambda Production
(Lam+LamBar) Rapidity Distribution: dN/dY
0.25
Rapidity Distribution Ratio: (Lam+LamBar)/(2Kshort)
0.5
_
CMS Data
(+)
7 TeV
PYTHIA Tune Z1
dN/dY Particle Ratio
dN/dY
0.20
0.15
0.10
900 GeV
0.05
CMS
NSD (all pT)
0.00
-4
-3
-2
-1
1
_
CMS
0.4
(+)/(2Kshort)
7 TeV
0.3
0.2
Factor of 1.5!
0.1
Tune Z1
NSD (all pT)
Tune Z1
0
CMS Data
PYTHIA Tune Z1
0.0
2
3
4
-4
-3
Rapidity Y
-2
-1
0
1
2
3
4
Rapidity Y
 CMS NSD data on the Lambda+AntiLambda  CMS NSD data on the Lambda+AntiLambda
rapidity distribution at 7 TeV and 900 GeV
to 2Kshort rapidity ratio at 7 TeV compared
compared with PYTHIA Tune Z1. The plot
with PYTHIA Tune Z1.
shows the average number of particles per
NSD collision per unit Y, (1/NNSD) dN/dY.

ud s
GGI Florence, Italy
September 14, 2011
“Minimum Bias” Collisions
Proton Tune Z1!
Oops!Proton
Not enough Lambda’s in PYTHIA
Rick Field – Florida/CDF/CMS
Page 64
LEP:  Spectrum
S350 Perugia 2011
Theory/Data
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 65
Cascade Production
Rapidity Distribution Ratio: (Cas+CasBar)/(2Kshort)
(Cas+CasBar) Rapidity Distribution: dN/dY
0.03
CMS Data

dN/dY Particle Ratio
7 TeV
dN/dY
0.02
CMS
900 GeV
0.01
PYTHIA Tune Z1
0.04
7 TeV
0.03
Factor of 2!
0.02
0.01
Tune Z1
NSD (all pT)
( + )/(2Kshort)
CMS
CMS Data

( + )
PYTHIA Tune Z1
_
0.05
_
Tune Z1
NSD (all pT)
0.00
0.00
-4
-3
-2
-1
0
1
2
3
4
-4
-3
-2
-1
0
1
2
3
4
Rapidity Y
Rapidity Y
 CMS NSD data on the Cascade CMS data on the Cascade-+AntiCascade- to
+AntiCascade- rapidity distribution at 7 TeV
2Kshort rapidity ratio at 7 TeV compared with
and 900 GeV compared with PYTHIA Tune
PYTHIA Tune Z1.
Z1. The plot shows the average number of
particles per NSD collision per unit Y,
(1/NNSD) dN/dY.
“Minimum Bias” Collisions
 
Proton Tune Z1!
Yikes! Proton
Way too few Cascade’s in PYTHIA
dss
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 66
LEP:  Spectrum
S350 Perugia 2011
0.05
Rapidity Distribution Ratio: (Cas+CasBar)/(2Kshort)
_
( + )/(2Kshort)
CMS Data
dN/dY Particle Ratio
PYTHIA Tune Z1 & S350
0.04
7 TeV
0.03
0.02
Theory/Data
0.01
pyZ1 = solid
pyS350 = dashed
NSD (all pT)
0.00
-4
-3
-2
-1
0
1
2
3
4
Rapidity Y
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 67
Transverse Momentum
Distributions
Cas+CasBar PT Distribution: dN/dPT
PT Distribution: Cas+CasBar
1.0E+00
1.0E-01
CMS Data
PYTHIA Tune Z1 & Z1C


( + )
Z1C
Z1
1.0E-03
NSD (|Y| < 2))
_


( + )
1.0E-02
7 TeV
PYTHIA Tune Z1 & Z1C
_
Probability
dN/dPT (1/GeV/c)
CMS Data
7 TeV
Z1C
1.0E-01
Z1
1.0E-02
Tune Z1C
qq/q: 0.1 -> 0.12
us/s: 0.4 -> 0.8
NSD (|Y| < 2))
Tune Z1C
qq/q: 0.1 -> 0.12
us/s: 0.4 -> 0.8
Normalized to 1
1.0E-03
1.0E-04
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
PT (GeV/c)
PT (GeV/c)
 CMS NSD data on the Cascade CMS NSD data on the Cascade+AntiCascade- transverse momentum
+AntiCascade- transverse momentum
distribution at 7 TeV compared with
distribution at 7 TeV (normalized to 1)
PYTHIA Tune Z1 & Z1C. The plot shows
compared with PYTHIA Tune Z1 & Z1C.
the average number of particles per NSD
collision per unit pT, (1/NNSD) dN/dpT for |Y| <
“Minimum Bias” Collisions
2.
Proton
PYTHIA Tune
Z1 & Z1C are a bit off on theProton
pT dependence!
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 68
7
Particle Ratios versus PT
Too many overall protons!
PT Particle Ratio: (P+Pbar)/Pions
Rapidity Distribution Ratio: (P+Pbar)/Pions
0.4
_
(p+p)/(p++p-)
ALICE Data
PYTHIA Tune Z1 & Z1C
_
(p+p)/(p++p-)
ALICE Data
PYTHIA Tune Z1 & Z1C
dN/dY Particle Ratio
PT Particle Ratio
0.12
0.3
Z1C
0.2
Z1
Tune Z1C
qq/q: 0.1 -> 0.12
us/s: 0.4 -> 0.8
0.1
900 GeV
INEL (|Y| < 0.75)
Z1C
0.09
0.06
Z1
0.03
900 GeV
INEL (all pT)
0.0
Tune Z1C
qq/q: 0.1 -> 0.12
us/s: 0.4 -> 0.8
0.00
0
1
2
PT (GeV/c)
3
4
-4
-3
Tails of the pT distribution.
Way off due to the wrong pT!
-2
-1
0
1
2
3
4
Rapidity Y
 ALICE INEL data on the Proton+AntiProton
 ALICE INEL data on the
to charged pions ratio versus pT at 900 GeV
Proton+AntiProton to charged pion rapidity
(|Y| < 0.75) compared with PYTHIA Tune Z1 &
ratio at 900 GeV compared with PYTHIA
Z1C.
Tune Z1 & Z1C.
“Minimum Bias” Collisions
p
uud
GGI Florence, Italy
September 14, 2011
Proton way off on the p dependence
Protonof Protons!
PYTHIA
T
Rick Field – Florida/CDF/CMS
Page 69
LEP: Proton Spectrum
S350 Perugia 2011
Rapidity Distribution Ratio: (P+Pbar)/Pions
0.12
_
(p+p)/(p++p-)
ALICE Data
dN/dY Particle Ratio
PYTHIA Tune Z1 & S350
0.09
0.06
Theory/Data
0.03
pyZ1 = solid
pyS350 = dashed
900 GeV
INEL (all pT)
0.00
-4
-3
-2
-1
0
1
2
3
4
Rapidity Y
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 70
MB versus UE
Charged Particle Density: dN/dhd
Transverse Charged Particle Density: dN/dhd
2.5
RDF Preliminary
CMS Data
PYTHIA Tune Z1
PYTHIA Tune Z1
Charged Particle Density
Charged Particle Density
2.5
2.0
Factor of 2!
1.5
1.0
Charged Particles (|h| < 2, all pT)
0.5
Tune Z1
CMS
2.0
Tune Z1
NSD = ND + DD
1.5
1.0
0.5
7 TeV ND
pyZ1 ND = dashed
7 TeV
NSD (all pT)
pyZ1 NSD = solid
0.0
0.0
0
5
10
15
20
25
-4
-3
-2
-1
0
1
2
3
Pseudo-Rapidity h
PT max (GeV/c)
 Shows the density of charged particles in
the “transverse” region as a function of
PTmax for charged particles (All pT, |h| <
2) at 7 TeV from PYTHIA Tune Z1.
Outgoing Parton
 CMS NSD data on the charged particle rapidity
distribution at 7 TeV compared with PYTHIA
Tune Z1. The plot shows the average number of
charged particles per NSD collision per unit h,
(1/NNSD) dN/dhd.
“Minimum Bias” Collisions
PT(hard)
Initial-State Radiation
Proton
Proton
Underlying Event
Outgoing Parton
GGI Florence, Italy
September 14, 2011
4
Proton
Underlying Event
Proton
Final-State
Radiation
Rick Field – Florida/CDF/CMS
Page 71
UE Particle Type
Log Scale!
Transverse Charged Particle Density: dN/dhd
Transverse Particle Density: dN/dhd
2.5
10.000
RDF Preliminary
PYTHIA Tune Z1
PYTHIA Tune Z1
2.0
Particle Density
Charged Particle Density
RDF Preliminary
1.5
1.0
Charged Particles (|h| < 2, all pT)
7 TeV ND
charged particles
(p++p-)
1.000
(K++K-)
_
(p+p
)
_
0.100
(+)
_
0.010
( + )
0.5
Tune Z1
7 TeV ND
(|h| < 2, all pT)
0.001
0.0
0
5
10
15
20
25
0
5
10
 Shows the density of charged particles in
the “transverse” region as a function of
PTmax for charged particles (All pT, |h| <
2) at 7 TeV from PYTHIA Tune Z1.
Outgoing Parton
PT(hard)
PT(hard)
Initial-State Radiation
Initial-State Radiation
Proton
Outgoing Parton
GGI Florence, Italy
September 14, 2011
25
 Shows the density of particles in the
“transverse” region as a function of
PTmax for charged particles (All pT, |h| <
2) at 7 TeV from PYTHIA Tune Z1.
Outgoing Parton
Underlying Event
20
PTmax (GeV/c)
PT max (GeV/c)
Proton
15
Underlying Event
Proton
Proton
Underlying Event
Final-State
Radiation
Outgoing Parton
Rick Field – Florida/CDF/CMS
Underlying Event
Final-State
Radiation
Page 72
MB versus UE
"Transverse" Particle Density: dN/dhd
Charged Particle Density: dN/dhd
0.15
0.15
RDF Preliminary
Charged Particle Density
Particle Density
RDF Preliminary
Kshort
PYTHIA Tune Z1
0.10
Factor of ~2!
0.05
Kshort (|h| < 2, all pT)
Tune Z1
Kshort
PYTHIA Tune Z1
0.10
0.05
Kshort (all pT)
Tune Z1
7 TeV ND
7 TeV ND
0.00
0.00
0
5
10
15
20
25
-4
-3
-2
-1
0
1
2
3
Pseudo-Rapidity h
PT max (GeV/c)
 Shows the density of Kshort particles in the
“transverse” region as a function of
PTmax for charged particles (All pT, |h| <
2) at 7 TeV from PYTHIA Tune Z1.
 Shows the Kshort pseudo-rapidity distribution (all
pT) at 7 TeV from PYTHIA Tune Z1. The plot
shows the average number of particles per ND
collision per unit h, (1/NND) dN/dhd.
Outgoing Parton
“Minimum Bias” Collisions
PT(hard)
Initial-State Radiation
Proton
Proton
Underlying Event
Outgoing Parton
GGI Florence, Italy
September 14, 2011
4
Proton
Underlying Event
Proton
Final-State
Radiation
Rick Field – Florida/CDF/CMS
Page 73
MB versus UE
Charged Particle Density: dN/dhd
"Transverse" Particle Density: dN/dhd
0.12
0.12
_
(p+p)
RDF Preliminary
RDF Preliminary
Charged Particle Density
Particle Density
PYTHIA Tune Z1
0.08
Factor of ~2!
0.04
Tune Z1
_
PYTHIA Tune Z1
(p+p)
0.08
0.04
7 TeV ND (all pT)
Tune Z1
7 TeV ND (|h| < 2,all pT)
0.00
0.00
0
5
10
15
20
25
-4
-3
-2
-1
0
1
2
3
Pseudo-Rapidity h
PT max (GeV/c)
 Shows the density of P+antiP particles in
the “transverse” region as a function of
PTmax for charged particles (All pT, |h| <
2) at 7 TeV from PYTHIA Tune Z1.
 Shows the P+antiP pseudo-rapidity distribution
(all pT) at 7 TeV from PYTHIA Tune Z1. The
plot shows the average number of particles per
ND collision per unit h, (1/NND) dN/dhd.
Outgoing Parton
“Minimum Bias” Collisions
PT(hard)
Initial-State Radiation
Proton
Proton
Underlying Event
Outgoing Parton
GGI Florence, Italy
September 14, 2011
4
Proton
Underlying Event
Proton
Final-State
Radiation
Rick Field – Florida/CDF/CMS
Page 74
MB versus UE
"Transverse" Particle Density: dN/dhd
_
0.04
RDF Preliminary
RDF Preliminary
Charged Particle Density
Particle Density
0.03
Factor of ~2!
0.02
Tune Z1
0.00
0
5
0.04
(+)
PYTHIA Tune Z1
0.01
Charged Particle Density: dN/dhd
PYTHIA Tune Z1
0.03
0.02
0.01
Coming soon! Measurements
from
CMS,
Tune Z1
7 TeV ND (|h| < 2,all pT)
ATLAS, and ALICE
on the strange
0.00
-4
-1
0
1
10
15
20
25
particles
and
baryons
in-3 the-2
Pseudo-Rapidity h
PT max (GeV/c)
“underlying event”.
 Shows the density of +anti particles in
the “transverse” region as a function of
PTmax for charged particles (All pT, |h| <
2) at 7 TeV from PYTHIA Tune Z1.
_
(+)
7 TeV ND (all pT)
2
3
 Shows the +anti pseudo-rapidity distribution
(all pT) at 7 TeV from PYTHIA Tune Z1. The
plot shows the average number of particles per
ND collision per unit h, (1/NND) dN/dhd.
Outgoing Parton
“Minimum Bias” Collisions
PT(hard)
Initial-State Radiation
Proton
Proton
Underlying Event
Outgoing Parton
GGI Florence, Italy
September 14, 2011
4
Proton
Underlying Event
Proton
Final-State
Radiation
Rick Field – Florida/CDF/CMS
Page 75
Fragmentation Summary
Beam-meam remnants!
Beam-meam remnants!
Charged Particle
dN/dhd
 StrangeCharged
Particle
Baryon
Particle &
Density:
dN/dhd Yields: PYTHIA is off

K+ Density:
Kshort
0.04
0.12
on RDF
thePreliminary
overall yield of Lambda’s and Cascades
RDF Preliminary u s
d s + d s(+ ud s
(p+p
(MC below the data) and too high on the0.03proton
p
0.08
 
K
yield. Difficult to fix this without destroying
0.02
uud
u s
dss
agreement
with
LEP!
0.04
0.01
7 TeV does
ND (all pT)not describe correctly the p
 PT Distributions: PYTHIA
7 TeV ND (all pT)
T distributions
0.00
0.00
of-10heavy
particles
(MC
softer
than
the
data).
None
of-4 the
fragmentation
-8
-6
-4
-2
0
2
4
6
8
10
-10
-8
-6
-2
0
2
4
6
8
10
parameters I have
looked
at changes the pT distributions.
Hence,
if one
Pseudo-Rapidity
h
Pseudo-Rapidity
h
looks at particle ratios at large pT you can see big discrepancies between
data and MC (out in the tails of the distributions)!
 Factorization: Are we seeing a breakdown in
“Minimum Bias” Collisions
+
factorization between e e annihilations and
Proton
Proton
hadron-hadron collisions! Is something
happening in hadron-hadron collisions that
does not happen in e+e- annihilations?
 Herwig++ & Sherpa: Before making any conclusions about fragmentation
one must check the predictions of Herwig++ and Sherpa carefully!
PYTHIA Tune Z1
GGI Florence, Italy
September 14, 2011
)
Charged Particle Density
Charged Particle Density
_
_
PYTHIA Tune Z1
Rick Field – Florida/CDF/CMS
)
Page 76
Sherpa versus PYTHIA
Strange particle production in pp at 200 GeV
(STAR_2006_S6860818)
<pT> versus Mass
 Before making any conclusion about e+eversus pp collisions one must check the
predictions of Herwig++ and Sherpa!
Sherpa does better
than PYTHIA 8!
Hendrik Hoeth
http://users.hepforge.org/~hoeth/STAR_2006_S6860818/
GGI Florence, Italy
September 14, 2011
Rick Field – Florida/CDF/CMS
Page 77