1st Workshop on Energy Scaling
in Hadron-Hadron Collisions
Fermilab 2009
From CDF to CMS
Rick Field
University of Florida
Outline of Talk
Outgoing Parton
PT(hard)
Extrapolating “min-bias” collisions
Proton
to the LHC.
Studying <pT> versus Nchg in
Initial-State Radiation
AntiProton
Underlying Event
Outgoing Parton
Underlying Event
Final-State
Radiation
“min-bias” collisions and in Drell-Yan.
LHC predictions!
Summary.
Fermilab Energy Scaling Workshop
April 29, 2009
CDF Run 2
Rick Field – Florida/CDF/CMS
CMS at the LHC
Page 1
Charged Particle Density: dN/dη
Charged Particle Density: dN/dη
η
Charged Particle Density: dN/dη
η
5.0
2.0
PY Tune A
generator level
4.0
3.0
2.0
PY64 Tune S320
PY64 Tune P329
1.0
Min-Bias
1.96 TeV
Charged Particles (all PT)
PY64 Tune P329
RDF Preliminary
Charged Particle Density
Charged Particle Density
RDF Preliminary
generator level
1.5
PY Tune A
1.0
PY64 Tune S320
0.5
Min-Bias
1.96 TeV
Charged Particles (PT>0.5 GeV/c)
0.0
0.0
-8
-6
-4
-2
0
2
4
6
8
-8
-6
PseudoRapidity η
-4
-2
0
2
4
6
8
PseudoRapidity η
Charged particle (all pT) pseudo-rapidity Charged particle (pT>0.5 GeV/c) pseudodistribution, dNchg/dη
ηdφ
φ, at 1.96 TeV for
inelastic non-diffractive collisions from
PYTHIA Tune A, Tune S320, and Tune
P324.
Fermilab Energy Scaling Workshop
April 29, 2009
rapidity distribution, dNchg/dη
ηdφ
φ, at 1.96
TeV for inelastic non-diffractive collisions
from PYTHIA Tune A, Tune S320, and
Tune P324.
Rick Field – Florida/CDF/CMS
Page 2
Charged Particle Density: dN/dη
RDF LHC Prediction!
Charged Particle Density: dN/dη
η
η
Charged Particle Density: dN/dη
5.0
8.0
generator level
4.0
3.0
2.0
PY64 Tune S320
PY64 Tune P329
1.0
PY64 Tune P329
PY Tune A
Charged Particle Density
Charged Particle Density
RDF Preliminary
Min-Bias
1.96 TeV
Charged Particles (all PT)
0.0
RDF Preliminary
generator level
6.0
4.0
PY Tune A
PY64 Tune S320
2.0
0.0
-8
-6
-4
-2
0
2
4
6
8
-8
-6
-4
-2
PseudoRapidity η
0
2
4
6
PseudoRapidity η
“Minumum Bias” Collisions
Proton
Min-Bias
14 TeV
Charged Particles (all PT)
“Minumum Bias” Collisions
AntiProton
Tevatron
Proton
Proton
LHC
Charged particle (all pT) pseudo-rapidity distribution, dNchg/dη
ηdφ
φ, at 1.96 TeV for
inelastic non-diffractive collisions from PYTHIA Tune A, Tune S320, and Tune P324.
Extrapolations of PYTHIA Tune A, Tune S320, and Tune P329 to the LHC.
Fermilab Energy Scaling Workshop
April 29, 2009
Rick Field – Florida/CDF/CMS
Page 3
8
Charged Particle Density: dN/dη
RDF LHC Prediction!
Charged Particle Density: dN/dη
η
2.0
4.0
PY64 Tune P329
RDF Preliminary
RDF Preliminary
Charged Particle Density
Charged Particle Density
η
Charged Particle Density: dN/dη
generator level
1.5
PY Tune A
1.0
PY64 Tune S320
0.5
Min-Bias
1.96 TeV
Charged Particles (PT>0.5 GeV/c)
PY64 Tune P329
generator level
3.0
PY64 Tune S320
2.0
PY Tune A
1.0
0.0
0.0
-8
-6
-4
-2
0
2
4
6
8
-8
-6
-4
-2
0
2
4
6
8
PseudoRapidity η
PseudoRapidity η
“Minumum Bias” Collisions
Proton
Min-Bias
14 TeV
Charged Particles (PT>0.5 GeV/c)
“Minumum Bias” Collisions
AntiProton
Tevatron
Proton
Proton
LHC
Charged particle (pT > 0.5 GeV/c) pseudo-rapidity distribution, dNchg/dη
ηdφ
φ, at 1.96 TeV
for inelastic non-diffractive collisions from PYTHIA Tune A, Tune S320, and Tune
P324.
Extrapolations of PYTHIA Tune A, Tune S320, and Tune P329 to the LHC.
Fermilab Energy Scaling Workshop
April 29, 2009
Rick Field – Florida/CDF/CMS
Page 4
Charged Particle Density: dN/dη
Why is py64 Tune P329 higher
than py Tune DWT??
RDF LHC Prediction!
Charged Particle Density: dN/dη
η
2.0
PY64 Tune P329
4.0
generator level
RDF Preliminary
PY Tune A
1.0
0.5
Charged Particle Density
1.5
PY Tune DWT
generator level
3.0
PY64 Tune S320
2.0
PY64 Tune S320
Min-Bias
1.96 TeV
Charged Particles (PT>0.5 GeV/c)
0.0
-8
-6
-4
PY Tune A
PY64 Tune P329
generator level
3.0
PY64 Tune P329
PY64 Tune S320
2.0
PY Tune A
1.0
Min-Bias
14 TeV
Charged Particles (PT>0.5 GeV/c)
0.0
1.0
-2
RDF Preliminary
Charged Particle Density
RDF Preliminary
Charged Particle Density
η
Charged Particle Density: dN/dη
η
Charged Particle Density:
dN/dη
4.0
0
2
4
6
-8
8
-6
PseudoRapidity η Charged Particles (PT>0.5 GeV/c)
-4
Min-Bias
14 TeV
-2
0
2
4
6
8
PseudoRapidity η
0.0
“Minumum Bias” Collisions
Proton
-8
-6
AntiProton
Tevatron
-4
-2
0
2
4
6
PseudoRapidity η
8
“Minumum Bias” Collisions
Proton
Proton
LHC
Charged particle (pT > 0.5 GeV/c) pseudo-rapidity distribution, dNchg/dη
ηdφ
φ, at 1.96 TeV
for inelastic non-diffractive collisions from PYTHIA Tune A, Tune S320, and Tune
P324.
Extrapolations of PYTHIA Tune A, Tune S320, and Tune P329 to the LHC.
Fermilab Energy Scaling Workshop
April 29, 2009
Rick Field – Florida/CDF/CMS
Page 5
Min-Bias Correlations
< pT > [GeV/c]
1.4
Average PT versus Nchg
Average PT (GeV/c)
1.4
CDF Run 2 Preliminary
pyDW
data corrected
generator level theory
“Minumum Bias” Collisions
1.2
Min-Bias
1.96 TeV
pyA
Proton
1.0
AntiProton
CDF RunII Preliminary
1.3
1.2
1.1
ATLAS
0.8
1
Charged Particles (|η
η|<1.0, PT>0.4 GeV/c)
0.6
0
10
20
30
40
50
0.9
|η|≤ 1 and pT ≥ 0.4 GeV
Number of Charged Particles
0.8
Data RunII MB+HM
Pythia TuneA, hadron level
0.7
0
5
10
15
20
25
30
35
40
45
50
multiplicity
Data at 1.96 TeV on the average pT of charged particles versus the number of charged particles (pT >
0.4 GeV/c, |η
η| < 1) for “min-bias” collisions at CDF Run 2. The data are corrected to the particle level
and are compared with PYTHIA Tune A at the particle level (i.e. generator level).
Fermilab Energy Scaling Workshop
April 29, 2009
Rick Field – Florida/CDF/CMS
Page 6
Min-Bias: Average PT versus Nchg
Beam-beam remnants (i.e. soft hard core) produces
Average PT versus Nchg
Average PT (GeV/c)
1.4
CDF Run 2 Preliminary
Min-Bias
1.96 TeV
data corrected
generator level theory
1.2
low multiplicity and small <pT> with <pT>
independent of the multiplicity.
Hard scattering (with no MPI) produces large
pyA
multiplicity and large <pT>.
pyAnoMPI
1.0
Hard scattering (with MPI) produces large
0.8
multiplicity and medium <pT>.
ATLAS
Charged Particles (|η
η|<1.0, PT>0.4 GeV/c)
0.6
0
5
10
15
20
25
30
35
40
This observable is sensitive
to the MPI tuning!
Number of Charged Particles
“Hard” Hard Core (hard scattering)
Outgoing Parton
“Soft” Hard Core (no hard scattering)
PT(hard)
CDF “Min-Bias”
=
Proton
+
AntiProton
Proton
AntiProton
Underlying Event
Underlying Event
Initial-State
Radiation
Final-State
Radiation
Multiple-Parton Interactions
+
Proton
AntiProton
Underlying Event
Outgoing Parton
Fermilab Energy Scaling Workshop
April 29, 2009
Outgoing Parton
PT(hard)
Initial-State
Radiation
The CDF “min-bias” trigger
picks up most of the “hard
core” component!
Outgoing Parton
Underlying Event
Final-State
Radiation
Rick Field – Florida/CDF/CMS
Page 7
Average PT versus Nchg
Average PT
PT versus
versus Nchg
Nchg
Average
Average PT versus Nchg
2.5
2.5
CDF Run 2 Preliminary
data corrected
generator level theory
1.2
CDFRun
Run22Preliminary
Preliminary
CDF
Min-Bias
1.96 TeV
Average
Average PT
PT (GeV/c)
(GeV/c)
Average PT (GeV/c)
1.4
pyA
pyAnoMPI
1.0
0.8
ATLAS
data corrected
generator
level theory
generator level theory
2.0
2.0
HW
HW
pyAW
pyAW
"Drell-YanProduction"
Production"
"Drell-Yan
70<<M(pair)
M(pair)<<110
110GeV
GeV
70
1.5
1.5
JIM
JIM
1.0
1.0
ATLAS
ATLAS
Charged Particles (|η
η|<1.0, PT>0.4 GeV/c)
0.6
ChargedParticles
Particles(|η
(|η
|<1.0,PT>0.5
PT>0.5GeV/c)
GeV/c)
Charged
ηη|<1.0,
excludingthe
thelepton-pair
lepton-pair
excluding
0.5
0.5
0
5
10
15
20
25
30
35
40
00
55
10
10
Number of Charged Particles
15
15
20
20
25
25
30
30
Numberof
ofCharged
ChargedParticles
Particles
Number
Drell-Yan Production
Lepton
“Minumum Bias” Collisions
Proton
AntiProton
Proton
AntiProton
Underlying Event
Underlying Event
Anti-Lepton
Data at 1.96 TeV on the average pT of charged particles versus the number of charged particles (pT > 0.4 GeV/c, |η
η| <
1) for “min-bias” collisions at CDF Run 2. The data are corrected to the particle leveland are compared with
PYTHIA Tune A, Tune DW, and the ATLAS tune at the particle level (i.e. generator level).
Particle level predictions for the average pT of charged particles versus the number of charged particles (pT > 0.5
GeV/c, |η
η| < 1, excluding the lepton-pair) for for Drell-Yan production (70 < M(pair) < 110 GeV) at CDF Run 2.
Fermilab Energy Scaling Workshop
April 29, 2009
Rick Field – Florida/CDF/CMS
Page 8
35
35
Average PT versus Nchg
Z-boson production (with low pT(Z) and no MPI)
No MPI!
Average PT versus Nchg
produces low multiplicity and small <pT>.
2.5
Average PT (GeV/c)
CDF Run 2 Preliminary
data corrected
generator level theory
2.0
HW
High pT Z-boson production produces large
pyAW
multiplicity and high <pT>.
"Drell-Yan Production"
70 < M(pair) < 110 GeV
Z-boson production (with MPI) produces large
1.5
multiplicity and medium <pT>.
JIM
1.0
ATLAS
Charged Particles (|η
η|<1.0, PT>0.5 GeV/c)
excluding the lepton-pair
0.5
0
5
10
15
20
25
30
35
Number of Charged Particles
Drell-Yan Production (no MPI)
High PT Z-Boson Production
Lepton
Initial-State Radiation
Outgoing Parton
Final-State Radiation
Drell-Yan
=
Proton
AntiProton
Underlying Event
Underlying Event
Anti-Lepton
+
+
Drell-Yan Production (with MPI)
Proton
Proton
Lepton
AntiProton
Z-boson
AntiProton
Underlying Event
Underlying Event
Anti-Lepton
Fermilab Energy Scaling Workshop
April 29, 2009
Rick Field – Florida/CDF/CMS
Page 9
Average PT(Z) versus Nchg
No MPI!
Average PT versus Nchg
PT(Z-Boson)
PT(Z-Boson) versus
versus Nchg
Nchg
2.5
80
80
data corrected
generator level theory
2.0
CDF
CDF Run
Run 22 Preliminary
Preliminary
HW
Average PT(Z) (GeV/c)
Average PT (GeV/c)
CDF Run 2 Preliminary
pyAW
"Drell-Yan Production"
70 < M(pair) < 110 GeV
1.5
JIM
1.0
ATLAS
Charged Particles (|η
η|<1.0, PT>0.5 GeV/c)
excluding the lepton-pair
generator
level theory
data corrected
generator level theory
60
60
pyAW
pyAW
HW
HW
"Drell-Yan
"Drell-Yan Production"
Production"
70
70 << M(pair)
M(pair) << 110
110 GeV
GeV
40
40
JIM
JIM
20
20
ATLAS
ATLAS
Charged
ηη|<1.0,
Charged Particles
Particles (|η
(|η
|<1.0, PT>0.5
PT>0.5 GeV/c)
GeV/c)
excluding
excluding the
the lepton-pair
lepton-pair
00
0.5
0
5
10
15
20
25
30
35
00
55
Outgoing Parton
Lepton
Initial-State Radiation
Proton
Proton
AntiProton
AntiProton
Underlying Event
Underlying Event
15
15
20
20
25
25
30
30
35
35
40
40
Number
Number of
of Charged
Charged Particles
Particles
Number of Charged Particles
High P
Production
T Z-BosonProduction
Drell-Yan
10
10
Predictions for the average PT(Z-Boson) versus
the number of charged particles (pT > 0.5
GeV/c, |η
η| < 1, excluding the lepton-pair) for for
Drell-Yan production (70 < M(pair) < 110 GeV)
at CDF Run 2.
Anti-Lepton
Z-boson
Data on the average pT of charged particles versus the number of charged particles (pT > 0.5 GeV/c, |η
η| < 1,
excluding the lepton-pair) for for Drell-Yan production (70 < M(pair) < 110 GeV) at CDF Run 2. The data are
corrected to the particle level and are compared with various Monte-Carlo tunes at the particle level (i.e.
generator level).
Fermilab Energy Scaling Workshop
April 29, 2009
Rick Field – Florida/CDF/CMS
Page 10
Average PT versus Nchg
PT(Z) < 10 GeV/c
Average
Charged
PT
versus
Nchg
Average
Average Charged
Charged PT
PT versus
versus Nchg
Nchg
Average
PT
(GeV/c)
AveragePT
PT(GeV/c)
(GeV/c)
Average
1.4
1.4
1.4
CDF
Run
Preliminary
CDF
CDF Run
Run 22
2 Preliminary
Preliminary
data corrected
generator
level
generator
level theory
theory
generator level theory
1.2
1.2
1.2
pyAW
pyAW
pyAW
JIM
JIM
No MPI!
1.0
1.0
1.0
HW
HW
HW
0.8
0.8
0.8
"Drell-Yan
Production"
"Drell-Yan
"Drell-Yan Production"
Production"
70
M(pair)
110
GeV
70
70 <<
< M(pair)
M(pair) <<
< 110
110 GeV
GeV
PT(Z)
10
GeV/c
PT(Z)
PT(Z) <<
< 10
10 GeV/c
GeV/c
ATLAS
ATLAS
Charged
Particles
(|η
|<1.0,
PT>0.5
GeV/c)
Charged
ηη
Charged Particles
Particles (|η
(|η
|<1.0, PT>0.5
PT>0.5 GeV/c)
GeV/c)
η|<1.0,
excluding
the
lepton-pair
excluding
excluding the
the lepton-pair
lepton-pair
0.6
0.6
0.6
00
0
55
5
10
10
10
15
15
15
20
20
20
25
25
25
30
30
30
35
35
35
Number
of
Charged
Particles
Number
Number of
of Charged
Charged Particles
Particles
Drell-Yan Production
Lepton
Proton
AntiProton
Underlying Event
Underlying Event
Anti-Lepton
Predictions
for thepTaverage
pT ofparticles
chargedversus
particles
theofnumber
charged(p
particles
(pT > 0.5
η|
Data the average
of charged
theversus
number
chargedofparticles
|η
η| GeV/c,
< 1, |η
T > 0.5 GeV/c,
<
1, excluding
the lepton-pair)
forDrell-Yan
for Drell-Yan
production
< M(pair)
< GeV,
110 GeV,
PT(pair)
10 GeV/c)
excluding
the lepton-pair)
for for
production
(70 <(70
M(pair)
< 110
PT(pair)
< 10<GeV/c)
at at
CDF Run 2. The data are corrected to the particle level and are compared with various Monte-Carlo tunes at
the particle level (i.e. generator level).
Fermilab Energy Scaling Workshop
April 29, 2009
Rick Field – Florida/CDF/CMS
Page 11
Average PT versus Nchg
PT(Z) < 10 GeV/c
Average
Charged
PT
versus
Nchg
Average
Average Charged
Charged PT
PT versus
versus Nchg
Nchg
Average PT versus Nchg
1.4
CDF
Run
Preliminary
CDF
CDF Run
Run 22
2 Preliminary
Preliminary
data corrected
generator
level
generator
level theory
theory
generator level theory
1.2
1.2
1.2
pyAW
pyAW
pyAW
1.0
1.0
1.0
HW
HW
HW
0.8
0.8
0.8
"Drell-Yan
Production"
"Drell-Yan
"Drell-Yan Production"
Production"
70
M(pair)
110
GeV
70
70 <<
< M(pair)
M(pair) <<
< 110
110 GeV
GeV
PT(Z)
10
GeV/c
PT(Z)
PT(Z) <<
< 10
10 GeV/c
GeV/c
CDF Run 2 Preliminary
JIM
JIM
Average PT (GeV/c)
Average
PT
(GeV/c)
AveragePT
PT(GeV/c)
(GeV/c)
Average
1.4
1.4
1.4
ATLAS
ATLAS
Drell-Yan PT > 0.5 GeV PT(Z) < 10 GeV/c
data corrected
generator level theory
1.2
pyAW
No MPI!
1.0
Min-Bias PT > 0.4 GeV/c
0.8
Charged
Particles
(|η
|<1.0,
PT>0.5
GeV/c)
Charged
ηη
Charged Particles
Particles (|η
(|η
|<1.0, PT>0.5
PT>0.5 GeV/c)
GeV/c)
η|<1.0,
excluding
the
lepton-pair
excluding
excluding the
the lepton-pair
lepton-pair
Charged Particles (|η
η|<1.0)
pyA
0.6
0.6
0.6
0.6
00
0
55
5
10
10
10
15
15
15
20
20
20
25
25
25
30
30
30
35
35
35
0
Number
of
Charged
Particles
Number
Number of
of Charged
Charged Particles
Particles
Drell-Yan Production
10
20
30
40
Number of Charged Particles
Lepton
Proton
AntiProton
Underlying Event
Underlying Event
Remarkably similar behavior!
Perhaps indicating that MPIProton
playing an important role in
both processes.
“Minumum Bias” Collisions
AntiProton
Anti-Lepton
Predictions
for thepTaverage
pT ofparticles
chargedversus
particles
theofnumber
charged(p
particles
(pT > 0.5
η|
Data the average
of charged
theversus
number
chargedofparticles
|η
η| GeV/c,
< 1, |η
T > 0.5 GeV/c,
<
1, excluding
the lepton-pair)
forDrell-Yan
for Drell-Yan
production
< M(pair)
< GeV,
110 GeV,
PT(pair)
10 GeV/c)
excluding
the lepton-pair)
for for
production
(70 <(70
M(pair)
< 110
PT(pair)
< 10<GeV/c)
at at
CDF Run 2. The data are corrected to the particle level and are compared with various Monte-Carlo tunes at
the particle level (i.e. generator level).
Fermilab Energy Scaling Workshop
April 29, 2009
Rick Field – Florida/CDF/CMS
Page 12
LHC Predictions
“Minumum Bias” Collisions
Proton
AntiProton
Charged Particle Density: dN/dη
η
4.0
RDF Preliminary
Charged Particle Density
I believe we are now in a position to make
some predictions at the LHC!
PY64 Tune P329
generator level
3.0
PY64 Tune S320
2.0
PY Tune A
1.0
Min-Bias
14 TeV
Charged Particles (PT>0.5 GeV/c)
0.0
The amount of activity in “min-bias” collisions.
Outgoing Parton
-8
-6
∆φ
“Toward”
Underlying Event
“Transverse”
Outgoing Parton
“Transverse”
Final-State
Radiation
“Away”
The amount of activity in the “underlying event” in hard
scattering events.
Drell-Yan Production
6
8
PY Tune DWT
RDF Preliminary
generator level
1.2
0.8
PY64 Tune P329
PY Tune A
0.4
PY Tune DW
PY64 Tune S320
Min-Bias
14 TeV
Charged Particles (|η
η|<1.0, PT>0.5 GeV/c)
0
5
10
15
20
25
PTmax (GeV/c)
Z-BosonDirection
∆φ
Lepton
"Toward" Charged Particle Density: dN/dη
ηdφ
φ
1.6
Underlying Event
“Transverse”
“Transverse”
“Away”
Anti-Lepton
The amount of activity in the “underlying event” in DrellYan events.
"Toward" Charged Density
RDF Preliminary
AntiProton
Underlying Event
4
0.0
“Toward”
Proton
2
"Transverse" Charged Particle Density: dN/dη
ηdφ
φ
1.6
"Transverse" Charged Density
Underlying Event
0
PseudoRapidity η
Initial-State Radiation
AntiProton
-2
PTmax Direction
PT(hard)
Proton
-4
PY Tune DWT
PY Tune DW
generator level
1.2
0.8
PY64 Tune P329
PY64 Tune S320
70 < M(pair) < 110 GeV
0.4
Drell-Yan
14 TeV
Charged Particles (|η
η|<1.0, PT>0.5 GeV/c)
0.0
0
25
50
75
100
125
150
Lepton-Pair PT (GeV/c)
Fermilab Energy Scaling Workshop
April 29, 2009
Rick Field – Florida/CDF/CMS
Page 13
LHC Predictions
“Minumum Bias” Collisions
Proton
AntiProton
Charged Particle Density: dN/dη
η
4.0
RDF Preliminary
Charged Particle Density
I believe we are now in a position to make
some predictions at the LHC!
PY64 Tune P329
generator level
3.0
PY64 Tune S320
2.0
PY Tune A
1.0
Min-Bias
14 TeV
Charged Particles (PT>0.5 GeV/c)
0.0
The amount of activity in “min-bias” collisions.
Outgoing Parton
Underlying Event
If the LHC data are not in
the range shown here then
we learn new physics!
“Toward”
“Transverse”
Outgoing Parton
Final-State
Radiation
“Transverse”
“Away”
The amount of activity in the “underlying event” in hard
scattering events.
Drell-Yan Production
2
4
6
8
PY Tune DWT
RDF Preliminary
generator level
1.2
0.8
PY64 Tune P329
PY Tune A
0.4
PY Tune DW
PY64 Tune S320
Min-Bias
14 TeV
Charged Particles (|η
η|<1.0, PT>0.5 GeV/c)
0
5
10
15
20
25
PTmax (GeV/c)
Z-BosonDirection
∆φ
Lepton
"Toward" Charged Particle Density: dN/dη
ηdφ
φ
1.6
Underlying Event
“Transverse”
“Transverse”
“Away”
Anti-Lepton
The amount of activity in the “underlying event” in DrellYan events.
"Toward" Charged Density
RDF Preliminary
AntiProton
Underlying Event
0
0.0
“Toward”
Proton
-2
"Transverse" Charged Particle Density: dN/dη
ηdφ
φ
1.6
"Transverse" Charged Density
AntiProton
-4
PseudoRapidity η
∆φ
Initial-State Radiation
Underlying Event
-6
PTmax Direction
PT(hard)
Proton
-8
PY Tune DWT
PY Tune DW
generator level
1.2
0.8
PY64 Tune P329
PY64 Tune S320
70 < M(pair) < 110 GeV
0.4
Drell-Yan
14 TeV
Charged Particles (|η
η|<1.0, PT>0.5 GeV/c)
0.0
0
25
50
75
100
125
150
Lepton-Pair PT (GeV/c)
Fermilab Energy Scaling Workshop
April 29, 2009
Rick Field – Florida/CDF/CMS
Page 14
Summary
However, I believe that the
better fits to the LEP
fragmentation data at high z
will lead to small improvements
Outgoing Parton
of Tune A at the
Tevatron!
We are making good progress in understanding and modeling the
“underlying event”.
PT(hard)
Initial-State Radiation
Proton
The new Pythia pT ordered tunes (py64 S320 and py64 P329)
are very similar to Tune A and Tune DW. At present the new
tunes do not fit the data better than Tune A and Tune DW.
However, the new tune are theoretically preferred!
AntiProton
Underlying Event
Underlying Event
Outgoing Parton
Final-State
Radiation
Hard-Scattering Cut-Off PT0
All tunes with the default value PARP(90) = 0.16
are wrong and are overestimating the activity of
min-bias and the underlying event at the LHC!
This includes all the ATLAS tunes!
Need to measure “Min-Bias” and the “underlying
event” at the LHC as soon as possible to see if there is
new QCD physics to be learned!
Fermilab Energy Scaling Workshop
April 29, 2009
Rick Field – Florida/CDF/CMS
PYTHIA 6.206
ε = 0.25 (Set A))
4
PT0 (GeV/c)
It is clear now that the default value PARP(90) = 0.16 is
not correct and the value should be closer to the Tune A
value of 0.25.
5
3
2
ε = 0.16 (default)
1
100
1,000
10,000
100,000
CM Energy W (GeV)
UE&MB@CMS
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