MB&UE Working Group Meeting
February 7 & 8, 2011
UE Lessons Learned & What’s Next
CMS
Rick Field
University of Florida
Outline of Talk
 LHC UE Data: ALICE-ATLAS-CMS UE data.
Comparisons with each other and with PYTHIA Tune Z1.
ATLAS
 LHC MB Data: Attempts to describe both MB and
the UE with the same tune.
 Coming Soon: Corrected UE from CMS!
Outgoing Parton
PT(hard)
Initial-State Radiation
Proton
Proton
Underlying Event
Underlying Event
UE&MB@CMS
Outgoing Parton
LPCC MB&UE Meeting
CERN February 8, 2011
Final-State
Radiation
Rick Field – Florida/CDF/CMS
Page 1
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!
LPCC MB&UE Meeting
CERN February 8, 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 2
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
LPCC MB&UE Meeting
CERN February 8, 2011
Rick Field – Florida/CDF/CMS
Page 3
Traditional Approach
CDF Run 1 Analysis Charged Particle Df Correlations
Leading Calorimeter Jet or
Charged Jet #1
Leading Charged Particle Jet or
PT > PTmin |h| < hcut
Direction
Leading Charged Particle or
2
“Transverse” region
very sensitive to the
“underlying event”!
Away RegionZ-Boson
“Toward-Side” Jet
Df
“Toward”
“Transverse”
“Transverse”
“Away”
Leading Object
Direction
Df
“Toward”
“Transverse”
“Transverse”
Transverse
Region
f
Leading
Object
Toward Region
Transverse
Region
“Away”
Away Region
0
-hcut
“Away-Side” Jet
h
+hcut
 Look at charged particle correlations in the azimuthal angle Df relative to a leading object (i.e.
CaloJet#1, ChgJet#1, PTmax, Z-boson). For CDF PTmin = 0.5 GeV/c hcut = 1.
 Define |Df| < 60o as “Toward”, 60o < |Df| < 120o as “Transverse”, and |Df| > 120o as

“Away”.
o
All three regions have the same area in h-f space, Dh×Df = 2hcut×120 = 2hcut×2/3. Construct
densities by dividing by the area in h-f space.
LPCC MB&UE Meeting
CERN February 8, 2011
Rick Field – Florida/CDF/CMS
Page 4
CMS UE Data
"Transverse" Charged Particle Density: dN/dhdf
"Transverse" Charged Particle Density: dN/dhdf
1.2
1.2
CMS Preliminary
D6T
7 TeV
data uncorrected
Theory + SIM
Charged Particle Density
Charged Particle Density
CMS Preliminary
0.8
900 GeV
DW
0.4
CMS
7 TeV
data uncorrected
pyZ1 + SIM
0.8
900 GeV
0.4
CMS
Tune Z1
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
0.0
0
5
10
15
20
25
30
35
40
45
50
0
5
 CMS preliminary data at 900 GeV and 7
TeV on the “transverse” charged particle
density, dN/dhdf, as defined by the leading
charged particle jet (chgjet#1) for charged
particles with pT > 0.5 GeV/c and |h| < 2.0.
The data are uncorrected and compared
with PYTHIA Tune DW and D6T after
detector simulation (SIM).
LPCC MB&UE Meeting
CERN February 8, 2011
15
20
25
30
35
40
45
50
PT(chgjet#1) GeV/c
PT(chgjet#1) GeV/c
Color reconnection suppression.
Color reconnection strength.
10
 CMS preliminary data at 900 GeV and 7
TeV on the “transverse” charged particle
density, dN/dhdf, as defined by the leading
charged particle jet (chgjet#1) for charged
particles with pT > 0.5 GeV/c and |h| < 2.0.
The data are uncorrected and compared
with PYTHIA Tune Z1 after detector
simulation (SIM).
Tune Z1 (CTEQ5L)
PARP(82) = 1.932
PARP(90) = 0.275
PARP(77) = 1.016
PARP(78) = 0.538
Rick Field – Florida/CDF/CMS
Tune Z1 is a PYTHIA 6.4 using
pT-ordered parton showers and
the new MPI model!
Page 5
CMS UE Data
"Transverse" Charged PTsum Density: dPT/dhdf
CMS Preliminary
D6T
data uncorrected
Theory + SIM
1.2
Charged PTsum Density (GeV/c)
Charged PTsum Density (GeV/c)
"Transverse" Charged PTsum Density: dPT/dhdf
1.6
7 TeV
0.8
DW
900 GeV
CMS
0.4
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
0
5
10
15
20
25
30
35
40
45
50
1.6
CMS Preliminary
7 TeV
data uncorrected
pyZ1 + SIM
1.2
0.8
900 GeV
CMS
0.4
Tune Z1
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
0.0
0
5
PT(chgjet#1) (GeV/c)
10
15
20
25
30
35
40
45
50
PT(chgjet#1) (GeV/c)
 CMS preliminary data at 900 GeV and 7
 CMS preliminary data at 900 GeV and 7
TeV on the “transverse” charged PTsum
TeV on the “transverse” charged PTsum
density, dPT/dhdf, as defined by the leading
density, dPT/dhdf, as defined by the leading
charged particle jet (chgjet#1) for charged
charged particle jet (chgjet#1) for charged
particles with pT > 0.5 GeV/c and |h| < 2.0.
particles with pT > 0.5 GeV/c and |h| < 2.0.
The data are uncorrected and compared
The data are uncorrected and compared
with PYTHIA Tune DW and D6T after
with PYTHIA Tune Z1 after detector
detector simulation (SIM).
simulation (SIM).
Color reconnection suppression.
Color reconnection strength.
LPCC MB&UE Meeting
CERN February 8, 2011
Tune Z1 (CTEQ5L)
PARP(82) = 1.932
PARP(90) = 0.275
PARP(77) = 1.016
PARP(78) = 0.538
Rick Field – Florida/CDF/CMS
Tune Z1 is a PYTHIA 6.4 using
pT-ordered parton showers and
the new MPI model!
Page 6
ATLAS UE Data
"Transverse" Charged PTsum Density: dPT/dhdf
"Transverse" Charged Particle Density: dN/dhdf
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
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|<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
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/dhdf, as defined by the leading
charged particle (PTmax) for charged
particles with pT > 0.5 GeV/c and |h| < 2.5.
The data are corrected and compared with
PYTHIA Tune Z1 at the generator level.
I read the points off
with a ruler!
5
 ATLAS published data at 900 GeV and 7
TeV on the “transverse” charged PTsum
density, dPT/dhdf, as defined by the leading
charged particle (PTmax) for charged
particles with pT > 0.5 GeV/c and |h| < 2.5.
The data are corrected and compared with
PYTHIA Tune Z1 at the generrator level.
ATLAS publication – arXiv:1012.0791
December 3, 2010
LPCC MB&UE Meeting
CERN February 8, 2011
Rick Field – Florida/CDF/CMS
Page 7
ALICE UE Data
"Transverse" Charged PTsum Density: dPT/dhdf
"Transverse" Charged Particle Density: dN/dhdf
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/dhdf, 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.
LPCC MB&UE Meeting
CERN February 8, 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/dhdf, 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 8
ALICE-ATLAS UE
"Transverse" Charged Particle"Transverse"
Density: dN/dhdfCharged
0.8
0.4
Tune Z1
0.0
0
5
7 TeV
RDF Preliminary
"Transverse" Charged Density
ALICE corrected data
Tune Z1 generator level
1.2
1.2
RDF Preliminary
"Transverse" Charged Density
"Transverse" Charged Density
1.2
Charged Particle Density: dN/dhdf
Particle "Transverse"
Density: dN/dhdf
|h| < 0.8
Tune Z1 generator level
0.8
900 GeV
ALICE
|h| < 2.5
0.4 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
ALICE (red)
ATLAS (blue)
0.4
Tune Z1
ATLAS
Charged Particles (|h|<2.5, PT>0.5 GeV/c)
0.0
10
15
20
7 TeV
25
0 Charged Particles
5
10 GeV/c)
(PT > 0.5
15
20
25
PTmax (GeV/c)
PTmax (GeV/c)
0.0
0
5
 ALICE preliminary data
at 900 GeV
and 710 
TeV on the “transverse” charged particle PTmax
density, dN/dhdf, 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.
LPCC MB&UE Meeting
CERN February 8, 2011
15
20
ATLAS
published
data at25 900 GeV and 7
TeV on the “transverse” charged particle
(GeV/c)
density, dN/dhdf, as defined by the leading
charged particle (PTmax) for charged
particles with pT > 0.5 GeV/c and |h| < 2.5.
The data are corrected and compared with
PYTHIA Tune Z1 at the generrator level.
Rick Field – Florida/CDF/CMS
Page 9
ALICE-ATLAS UE
"Transverse" Charged PTsum Density: dPT/dhdf
1.5
ALICE corrected data
Tune Z1 generator level
0.5
PTsum Density (GeV/c)
1.0
Tune Z1
0.0
0
5
RDF Preliminary
7 TeV
RDF Preliminary
Tune Z1 generator level
|h| < 0.8
1.0
900 GeV
ALICE
0.5
15
PTmax (GeV/c)
7 TeV
ATLAS corrected data
Tune Z1 generator level
1.0
900 GeV
0.5
ALICE (red)
ATLAS (blue)
Tune Z1
Charged Particles (|h|<0.8, PT>0.5 GeV/c)
|h| < 2.5
10
PTsum Density (GeV/c)
RDF Preliminary
PTsum Density (GeV/c)
"Transverse" Charged PTsum Density: dPT/dhdf
"Transverse" Charged PTsum
Density: dPT/dhdf
1.5
1.5
ATLAS
Charged Particles (|h|<2.5, PT>0.5 GeV/c)
0.0
20
7 TeV
25
0
5
10
15
20
25
Charged Particles (PT > 0.5PTmax
GeV/c) (GeV/c)
0.0
 ALICE preliminary data
at 9005 GeV and 10
7  ATLAS
published
data 25
at 900 GeV and 7
0
15
20
TeV on the “transverse” charged particle PTmax (GeV/c)
TeV on the “transverse” charged particle
density, dN/dhdf, as defined by the leading
density, dN/dhdf, as defined by the leading
charged particle (PTmax) for charged
charged particle (PTmax) for charged
particles with pT > 0.5 GeV/c and |h| < 0.8.
particles with pT > 0.5 GeV/c and |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 generrator level.
LPCC MB&UE Meeting
CERN February 8, 2011
Rick Field – Florida/CDF/CMS
Page 10
PYTHIA Tune Z1
"Transverse" Charged Particle Density: dN/dhdf
2.5
1.5
1.0
0.5
0.0
2
4
6
3.0
PT > 0.5 GeV/c
2.0
ATLAS
Charged Particles (|h|<2.5)
1.0
8
7 TeV
RDF Preliminary
2.0
PT > 0.1 GeV/c
generator level
Tune Z1 (solid)
Tune DW (dashed)
1.5
1.0
ATLAS
0.5
PT > 0.5 GeV/c
Tune Z1
Charged Particles (|h|<2.5)
0.0
10
12
14
16
18
Charge PTsum Density
PTmax (GeV/c)
Factor of 2 increase!
RDF Preliminary
ATLAS corrected data
Tune Z1 generator level
Charge Particle Density
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/dhdf
"Transverse" Ratio: PT > 2.5
0.1 and > 0.5 GeV/c
20
0
2
4
7 TeV
6
8
10
12
14
16
18
20
Charged Particles (|h|<2.5)
PTmax (GeV/c)
0.0
 ATLAS preliminary data
at2 7 TeV

preliminary
0
4 on 6the 8
10 ATLAS
12
14
16
18 data
20 at 7 TeV on the
“transverse” charged particle density,
“transverse” charged PTsum density,
PTmax (GeV/c)
dN/dhdf, as defined by the leading charged
dPT/dhdf, 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
LPCC MB&UE Meeting
CERN February 8, 2011
Rick Field – Florida/CDF/CMS
Page 11
ATLAS UE Data
"Transverse"Charged
ChargedParticle
Particle Density:
Density: dN/dhdf
dN/dhdf
"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/dhdf
dPT/dhdf
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)
0.0
 ATLAS published data
at 7 TeV on the
10 ATLAS
published
data
at207 TeV on the
0
2
4
6
8
12
14
16
18
“transverse” charged particle density,
“transverse” charged PTsum density,
PTmax (GeV/c)
dN/dhdf, as defined by the leading charged
dPT/dhdf, 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.
I read the points off
with a ruler!
ATLAS publication – arXiv:1012.0791
December 3, 2010
LPCC MB&UE Meeting
CERN February 8, 2011
Rick Field – Florida/CDF/CMS
Page 12
“Transverse” Multiplicity Distribution
Same hard"Transverse"
scale at Charged Particle Multiplicity
1.0E+00 centertwo different
PT(chgjet#1) > 3 GeV/c
CMS Preliminary
of-mass
energies!
data uncorrected
1.0E-01
"Transverse" Charged Particle Multiplicity
1.0E+00
PT(chgjet#1) > 3 GeV/c
CMS
1.0E-02
Probability
CMS
1.0E-02
Probability
CMS Preliminary
data uncorrected
Theory + SIM
1.0E-01
1.0E-03
7 TeV
900 GeV
1.0E-04
D6T
1.0E-05
pyZ1 + SIM
Tune Z1
1.0E-03
7 TeV
900 GeV
1.0E-04
1.0E-05
DW
Normalized to 1
Normalized to 1
1.0E-06
1.0E-06
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
1.0E-07
1.0E-07
0
5
10
15
20
25
30
35
40
Number of Charged Particles
5
10
15
20
25
30
35
40
Number of Charged Particles
Difficultdata
to produce
CMS uncorrected
at 900 GeV and
enough
events
with
7 TeV on the charged particle
“transverse”
multiplicitylarge
distribution
in the
multiplicity
at
low
“transverse” region for charged
hard
scale!|h| < 2) as
particles (pT > 0.5
GeV/c,
defined by the leading charged particle
jet with PT(chgjet#1) > 3 GeV/c
compared with PYTHIA Tune Z1 at the
detector level (i.e. Theory + SIM).
Rick Field – Florida/CDF/CMS
Page 13
 CMS uncorrected data at 900 GeV and 7 TeV on 
the charged particle multiplicity distribution in
the “transverse” region for charged particles (pT
> 0.5 GeV/c, |h| < 2) as defined by the leading
charged particle jet with PT(chgjet#1) > 3 GeV/c
compared with PYTHIA Tune DW and Tune
D6T at the detector level (i.e. Theory + SIM).
LPCC MB&UE Meeting
CERN February 8, 2011
0
“Transverse” PTsum Distribution
Same hard
scale at
"Transverse"
Charged PTsum Distribution
1.0E+00
two different
centerCMS Preliminary
PT(chgjet#1) > 3 GeV/c
data uncorrected
of-mass energies!
"Transverse" Charged PTsum Distribution
1.0E+00
CMS Preliminary
1.0E-01
data uncorrected
Theory + SIM
1.0E-02
CMS
7 TeV
D6T
1.0E-04
pyZ1+ SIM
Tune Z1
1.0E-02
1.0E-03
900 GeV
CMS
1.0E-01
Probability
Probability
PT(chgjet#1) > 3 GeV/c
7 TeV
1.0E-03
900 GeV
1.0E-04
DW
1.0E-05
1.0E-05
Normalized to 1
Normalized to 1
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
1.0E-06
1.0E-06
0
5
10
15
20
25
30
35
40
45
50
0
PTsum (GeV/c)
5
10
15
20
25
30
35
40
45
50
PTsum (GeV/c)
 CMS uncorrected data at 900 GeV and 7
 CMS uncorrected data at 900 GeV and 7
Difficultscalar
to produce
TeV on the charged scalar PTsum
TeV on the charged
PTsum
enough
events
with region for
distribution in the “transverse” region for
distribution in the “transverse”
large (p
“transverse”
charged particles (pT > 0.5 GeV/c, |h| < 2) as
charged particles
T > 0.5 GeV/c, |h| < 2) as
PTsum
low particle jet
defined by the leading charged particle jet
defined by the leading at
charged
hard
with PT(chgjet#1) > 3 GeV/c compared with
with PT(chgjet#1)
> 3 scale!
GeV/c compared with
PYTHIA Tune DW, and Tune D6T at the
PYTHIA Tune Z1, at the detector level (i.e.
detector level (i.e. Theory + SIM).
Theory + SIM).
LPCC MB&UE Meeting
CERN February 8, 2011
Rick Field – Florida/CDF/CMS
Page 14
“Transverse” Multiplicity Distribution
"Transverse" Charged Particle Multiplicity
"Transverse" Charged Particle Multiplicity
Same
center-of-mass
1.0E+00
energy at two different 7 TeV
1.0E-01
hard scales!
CMS
1.0E+00
7 TeV
CMS Preliminary
data uncorrected
Theory + SIM
1.0E-01
CMS
1.0E-02
1.0E-02
data uncorrected
pyZ1 + SIM
Tune Z1
PT(chgjet#1) > 20 GeV/c
Probability
Probability
PT(chgjet#1) > 20 GeV/c
D6T
1.0E-03
CMS Preliminary
1.0E-04
PT(chgjet#1) > 3 GeV/c
1.0E-03
1.0E-04
PT(chgjet#1) > 3 GeV/c
1.0E-05
1.0E-05
DW
Normalized to 1
Normalized to 1
1.0E-06
1.0E-06
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
1.0E-07
1.0E-07
0
5
10
15
20
25
30
Number of Charged Particles
35
40
0
5
10
15
20
25
30
35
40
Number of Charged Particles
Difficult
to at
produce
 CMS uncorrected
data
7 TeV on the
 CMS uncorrected data at 7 TeV on the
enough
events with
charged particle
multiplicity
distribution in
charged particle multiplicity distribution in
largeregion
“transverse”
for charged particles
the “transverse” region for charged particles the “transverse”
multiplicity
low by the
(pT > 0.5 GeV/c,
|h| < 2) asatdefined
(pT > 0.5 GeV/c, |h| < 2) as defined by the
hard scale!
leading charged particle
jet with
leading charged particle jet with
PT(chgjet#1) > 3 GeV/c and PT(chgjet#1) >
PT(chgjet#1) > 3 GeV/c and PT(chgjet#1) >
20 GeV/c compared with PYTHIA Tune DW 20 GeV/c compared with PYTHIA Tune Z1
at the detector level (i.e. Theory + SIM).
and Tune D6T at the detector level (i.e.
Theory
+ SIM).
LPCC
MB&UE
Meeting
Rick Field – Florida/CDF/CMS
Page 15
CERN February 8, 2011
“Transverse” PTsum Distribution
Same center-of-mass
"Transverse" Charged PTsum Distribution
energy 1.0E+00
at two different
7 TeV
CMS Preliminary
hard scales!
data uncorrected
"Transverse" Charged PTsum Distribution
1.0E+00
7 TeV
CMS Preliminary
data uncorrected
Theory + SIM
1.0E-01
CMS
1.0E-02
CMS
1.0E-02
PT(chgjet#1) > 20 GeV/c
Probability
Probability
1.0E-01
1.0E-03
PT(chgjet#1) > 3 GeV/c
1.0E-04
pyZ1 + SIM
Tune Z1
PT(chgjet#1) > 20 GeV/c
1.0E-03
PT(chgjet#1) > 3 GeV/c
1.0E-04
D6T
Normalized to 1
1.0E-05
Normalized to 1
1.0E-05
DW
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
1.0E-06
1.0E-06
0
5
10
15
20
25
30
35
40
45
50
0
PTsum (GeV/c)
5
10
15
20
25
30
35
40
45
50
PTsum (GeV/c)
 CMS uncorrected data at 7 TeV on the charged
 CMS uncorrected data at 7 TeV on the
Difficult in
to the
produce
PTsum distribution
“transverse” region
charged PTsum distribution in the
enough
events
with
for charged particles (pT > 0.5 GeV/c, |h| < 2) as
“transverse” region for charged particles (pT
large
“transverse”
defined by the
leading
charged particle jet with
> 0.5 GeV/c, |h| < 2) as defined by the leading
PTsum
at
low PT(chgjet#1) > 20
PT(chgjet#1) > 3 GeV/c and
charged particle jet with PT(chgjet#1) > 3
hard
GeV/c compared
withscale!
PYTHIA Tune Z1 at the
GeV/c and PT(chgjet#1) > 20 GeV/c
detector level (i.e. Theory + SIM).
compared with PYTHIA Tune DW and Tune
D6T at the detector level (i.e. Theory + SIM).
LPCC MB&UE Meeting
CERN February 8, 2011
Rick Field – Florida/CDF/CMS
Page 16
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
LPCC MB&UE Meeting
CERN February 8, 2011
Okay not perfect!
But not that bad!
Rick Field – Florida/CDF/CMS
Proton
Page 17
MB & UE
"Transverse" Charged Particle Multiplicity
Charged Multiplicity Distribution
1.0E+00
1.0E-01
“Min-Bias”
RDF Preliminary
PT(chgjet#1) > 3 GeV/c
data CMS NSD
pyZ1 generator level
CMS
1.0E-02
Probability
Probability
data uncorrected
pyZ1 + SIM
1.0E-01
CMS
1.0E-02
CMS Preliminary
7 TeV
Tune Z1
1.0E-03
7 TeV
900 GeV
1.0E-04
900 GeV
1.0E-03
“Underlying Event”
1.0E-05
Normalized to 1
Charged Particles
(all PT, |h|<2.0)
1.0E-04
0
20
1.0E-06
Difficult to produce
40
60
80
enough
events
with
Number of Charged Particles
large multiplicity!
1.0E-07
100
0
5
10
15
20
25
30
35
40
Number of Charged Particles
 CMS uncorrected
Difficult
data
to produce
at 900 GeV and
7 TeV on theenough
charged
events
particle
with
multiplicity distribution
large “transverse”
in the
“transverse”multiplicity
region for charged
at low
particles (pT > 0.5
hard
GeV/c,
scale!
|h| < 2) as
defined by the leading charged particle
jet with PT(chgjet#1) > 3 GeV/c
compared with PYTHIA Tune Z1 at the
detector level (i.e. Theory + SIM).
Rick Field – Florida/CDF/CMS
Page 18
 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.
LPCC MB&UE Meeting
CERN February 8, 2011
Charged Particles (|h|<2.0, PT>0.5 GeV/c)
Tune Z1
MB & UE
ChargedParticle
ParticleMultiplicity
Multiplicity
Charged
1.0E+00
1.0E+00
CMS
TeV
77 TeV
CMS Preliminary
Preliminary
CMS
Tune Z1
Z1
Tune
Min-Bias
NSD All pT
1.0E-01
1.0E-01
Probability
Probability
Min-Bias
NSD All pT
1.0E-02
1.0E-02
Underlying Event
"Transverse" Region
pT > 0.5 GeV/c
PT(chgjet#1) > 20 GeV/c
1.0E-03
1.0E-03
1.0E-04
1.0E-04
Normalizedto
to11
Normalized
Underlying Event
"Transverse" Region
pT > 0.5 GeV/c
PT(chgjet#1) > 20 GeV/c
Tune Z1
Charged Particles (|h|<2.0)
Charged Particles (|h|<2.0)
1.0E-05
1.0E-05
00
5
2010
1540
20
60
25
30 80 35
100
40
Number of
of Charged
Charged Particles
Particles
Number
 CMS uncorrected data at 7 TeV on the charged particle multiplicity distribution in the
“transverse” region for charged particles (pT > 0.5 GeV/c, |h| < 2) as defined by the leading
charged particle jet with PT(chgjet#1) > 20 GeV/c compared with PYTHIA Tune Z1 at the
detector level (i.e. Theory + SIM). Also shows the CMS corrected NSD multiplicity
distribution (all pT, |h| < 2) compared with Tune Z1 at the generator.
Amazing what we are asking the Monte-Carlo models to fit!
LPCC MB&UE Meeting
CERN February 8, 2011
Rick Field – Florida/CDF/CMS
Page 19
CMS Corrected Data
Coming soon!
"Transverse" Charged PTsum Density: dPT/dhdf
"Transverse" Charged Particle Density: dN/dhdf
2.0
1.6
RDF Preliminary
PTsum Density (GeV/c)
Charged Particle Density
RDF Preliminary
Tune Z1 generator level
1.2
0.8
CMS (red)
ATLAS (blue)
0.4
Tune Z1 generator level
1.6
1.2
CMS (red)
ATLAS (blue)
0.8
0.4
7 TeV
Charged Particles (PT > 0.5 GeV/c)
7 TeV
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
100
PTmax or PT(chgjet#1) (GeV/c)
PTmax or PT(chgjet#1) (GeV/c)
 ATLAS published data at 7 TeV on the
“transverse” charged particle density,
dN/dhdf, as defined by the leading charged
particle (PTmax) for charged particles with
pT > 0.5 GeV/c (|h| < 2.5). The data are
corrected and compared with PYTHIA Tune
Z1 at the generator level.
Coming soon! CMS corrected data at 7 TeV on the
“transverse” charged particle density as defined by the
leading charged particle jet, PT(chgjet#1), for charged
particles with pT > 0.5 GeV/c (|h| < 2).
LPCC MB&UE Meeting
CERN February 8, 2011
20
 ATLAS published data at 7 TeV on the
“transverse” charged PTsum density,
dPT/dhdf, as defined by the leading charged
particle (PTmax) for charged particles with
pT > 0.5 GeV/c (|h| < 2.5). The data are
corrected and compared with PYTHIA Tune
Z1 at the generator level.
Coming soon! CMS corrected data at 7 TeV on the
“transverse” charged PTsum density as defined by the
leading charged particle jet, PT(chgjet#1), for charged
particles with pT > 0.5 GeV/c (|h| < 2).
Rick Field – Florida/CDF/CMS
Page 20
CMS Corrected Data
Coming soon!
"Transverse" Charged PTsum Density: dPT/dhdf
"Transverse" Charged Particle Density: dN/dhdf
0.8

RDF Preliminary
RDF Preliminary
PTsum Density (GeV/c)
Charged Particle Density
0.8
Tune Z1 generator level
0.6
0.4
CMS (red)
ATLAS (blue)
0.2
Tune Z1 generator level
0.6
0.4
CMS (red)
ATLAS (blue)
0.2
900 GeV
Also new CMS UE results using
0.0
0.0
the “jet
area”
approach
0
5will
10
15
20
0
5
10
15
20
25
PT(chgjet#1) GeV/c
PTmax or PT(chgjet#1) GeV/c
be coming soon at 7 TeV
ATLAS published data at 900with
GeV on
the
 ATLAS
comparisons
to 900 published
GeV! data at 900 GeV on the
900 GeV
“transverse” charged particle density,
dN/dhdf, as defined by the leading charged
particle (PTmax) for charged particles with
pT > 0.5 GeV/c (|h| < 2.5). The data are
corrected and compared with PYTHIA Tune
Z1 at the generator level.
Coming soon! CMS corrected data at 900 GeV on the
“transverse” charged particle density as defined by the
leading charged particle jet, PT(chgjet#1), for charged
particles with pT > 0.5 GeV/c (|h| < 2).
LPCC MB&UE Meeting
CERN February 8, 2011
Charged Particles (PT > 0.5 GeV/c)
Charged Particles (PT > 0.5 GeV/c)
25
“transverse” charged PTsum density,
dPT/dhdf, as defined by the leading charged
particle (PTmax) for charged particles with
pT > 0.5 GeV/c (|h| < 2.5). The data are
corrected and compared with PYTHIA Tune
Z1 at the generator level.
Coming soon! CMS corrected data at 900 GeV on the
“transverse” charged PTsum density as defined by the
leading charged particle jet, PT(chgjet#1), for charged
particles with pT > 0.5 GeV/c (|h| < 2).
Rick Field – Florida/CDF/CMS
Page 21
UE Summary
 The “underlying event” at 7 TeV and 900
GeV is almost what we expected! The
new tunes, AMBT1, Tune Z1, and
Proton
PYTHIA8 do a fairly good job of
describing the LHC UE data. Need to Underlying Event
also fit the Tevatron UE data!
 For the UE there was more “soft” particles
than expected and more “soft” high
multiplicity events than expected. The
high multiplicity events need to be studied
in much more detail!
PT(hard)
Initial-State Radiation
Proton
Underlying Event
Outgoing Parton
 “Min-Bias” is much more complicated due to
diffraction! Also more strange particles and
baryons than expected in MB! Also more
high multiplicity events than expected. The
high multiplicity events need to be studied in
much more detail!
LPCC MB&UE Meeting
CERN February 8, 2011
Outgoing Parton
Rick Field – Florida/CDF/CMS
Final-State
Radiation
No model describes all
the features PARP(82)
of the LHC
PARP(90) MB data!
Color
Diffraction
Connections
Page 22