Multiple Parton Interactions
and the Underlying Event
Session I: Experiment
Rick Field
University of Florida
(for the CDF & CMS Collaborations)
Some Topics
 What do we know about the soft
Outgoing Parton
underlying event?
 What do we know about hard
multiple interactions?
DESY, May 18-19 2007
PT(hard)
Initial-State Radiation
Proton
AntiProton
Underlying Event
 What about correlations?
 What is needed for LHC predictions?
 Monte-Carlo underlying event tunes.
 What are the measurements needed to better
Outgoing Parton
Underlying Event
Final-State
Radiation
Contributors
 L. Marti
 S. Osman
 L. Joennson
 J. Turnau
 L. Goerlich
understand MPI?
 Can HERA Contribute?
 What other Tevatron measurements do we need?
MPI & UE - DESY
May 18-19, 2007
Rick Field – Florida/CDF/CMS
Page 1
MIT Search Scheme: Vista/Sleuth
Exclusive 3 Jet Final State Challenge
At least 1 Jet (“trigger” jet)
(PT > 40 GeV/c, |h| < 1.0)
CDF Data
Normalized to 1
PYTHIA
Tune A
Exactly 3 jets
(PT > 20 GeV/c, |h| < 2.5)
R(j2,j3)
Order Jets by PT
Jet1 highest PT, etc.
Bruce Knuteson
Khaldoun
Makhoul
MPI & UE - DESY
May 18-19, 2007
Georgios
Choudalakis
Markus
Klute
Conor
Henderson
Rick Field – Florida/CDF/CMS
Ray
Culbertson
Gene
Flanagan
Page 2
Exc3J: R(j2,j3) Normalized
The data have more
3 jet events with
small R(j2,j3)!?
 Let Ntrig40 equal the number of events
Exclusive 3-Jet Production: R(j2,j3)
with at least one jet with PT > 40 geV and
|h| < 1.0 (this is the “offline” trigger).
0.16
 Let N3Jexc20 equal the number of events
0.12
with exactly three jets with PT > 20 GeV/c
and |h| < 2.5 which also have at least one
jet with PT > 40 GeV/c and |h| < 1.0.
 Let N3JexcFr = N3Jexc20/Ntrig40. The is
the fraction of the “offline” trigger events
that are exclusive 3-jet events.
Initial-State Radiation
0.08
Normalized to
N3JexcFr
0.04
0.00
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
Underlying Event
 PARP(67) affects the initial-state radiation which
contributes primarily to the region R(j2,j3) > 1.0.
“Jet 3”
Outgoing Parton
Initial-State Radiation
“Jet 2”
R > 1.0
MPI & UE - DESY
May 18-19, 2007
5.0
R(j2,j3)
with PYTHIA Tune AW (PARP(67)=4), Tune DW
(PARP(67)=2.5), Tune BW (PARP(67)=1).
AntiProton
Underlying Event
Data R(j2,j3)
pyAW
pyDW
pyBW
data uncorrected
generator level theory
 The CDF data on dN/dR(j2,j3) at 1.96 TeV compared
Outgoing Parton
“Jet 1”
Proton
dN/dR(j2,j3)
CDF Run 2 Preliminary
Rick Field – Florida/CDF/CMS
Page 3
3Jexc R(j2,j3) Normalized
 Let Ntrig40 equal the number of events
Exclusive
Exclusive 3-Jet
3-Jet Production:
Production: R(j2,j3)
R(j2,j3)
0.16
0.80
0.16
with at least one jet with PT > 40 geV and
|h| < 1.0 (this is the “offline” trigger).
0.12
0.60
0.12
dN/dR(j2,j3)
dN/dR(j2,j3)
dN/dR(j2,j3)
 Let N3Jexc20 equal the number of events
CDF Run
Run 22 Preliminary
Preliminary
CDF
with exactly three jets with PT > 20 GeV/c
0.08
0.40
0.08
I do not understand
the
and |h| < 2.5 which also have at least one
excess number
of events
0.04
jet with PT > 40 GeV/c and |h| < 1.0.
0.20
0.04
data
uncorrected
datauncorrected
uncorrected
data
generator
level
theory
generatorlevel
leveltheory
theory
generator
CDF Data
Data
Data R(j2,j3)
R(j2,j3)
hw05
pyDW
pyDW
pyDW
pyDWnoFSR
hw05
pyBW
Normalized to
N3JexcFr
with R(j2,j3) < 1.0.
Normalized to 1
 Let N3JexcFr = N3Jexc20/Ntrig40.
The is this0.00
Perhaps
is
related
to the
0.00
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
the fraction of the “offline” trigger“soft
eventsenergy”
0.0 problem??
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
R(j2,j3)
R(j2,j3)
that are exclusive 3-jet events.
For now the best tune is
 The Tune
CDF data
PYTHIA
DW.on dN/dR(j2,j3) at 1.96 TeV compared
Final-State Radiation
Outgoing Parton
“Jet 1”
with PYTHIA Tune DW (PARP(67)=2.5) and
HERWIG (without MPI).
Proton
AntiProton
Underlying Event
Underlying Event
Outgoing Parton
Final-State Radiation
“Jet “Jet
2” 3”
R < 1.0
MPI & UE - DESY
May 18-19, 2007
 Final-State radiation contributes to the region R(j2,j3)
< 1.0.
 If you ignore the normalization and normalize all the
distributions to one then the data prefer Tune BW, but
I believe this is misleading.
Rick Field – Florida/CDF/CMS
Page 4
Latest CDF Run 2
“Underlying Event” Results
Jet #1 Direction

“Toward”
“Trans 1”
The “underlying event” consists of
hard initial & final-state radiation
plus the “beam-beam remnants” and
possible multiple parton interactions.
Outgoing Parton
“Trans 2”
PT(hard)
Initial-State Radiation
“Away”
Proton
AntiProton
Underlying Event
Craig Group and I are redoing
This analysis with 1 fb-1.
Outgoing Parton
Hope to publish it by the
-1) :summer!
end pb
of the
New CDF Run 2 results (L = 385
“Transverse” region is
very sensitive to the
“underlying event”!
Underlying Event
Final-State
Radiation
 Two Classes of Events: “Leading Jet” and “Back-to-Back”.
 Two “Transverse” regions: “transMAX”, “transMIN”, “transDIF”.
 Data Corrected to the Particle Level: unlike our previous CDF Run 2 “underlying event”
analysis which used JetClu to define “jets” and compared uncorrected data with the QCD
Monte-Carlo models after detector simulation, this analysis uses the MidPoint jet algorithm and
corrects the observables to the particle level. The corrected observables are then compared
with the QCD Monde-Carlo models at the particle level.
 For the 1st time we study the energy density in the “transverse” region.
MPI & UE - DESY
May 18-19, 2007
Rick Field – Florida/CDF/CMS
Page 5
“Transverse” Observables
Particle and Detector Level
“Leading Jet”
Jet #1 Direction
Observable
Particle Level
Detector Level
dNchg/dhd
Number of charged particles
per unit h-
(pT > 0.5 GeV/c, |h| < 1)
Number of “good” charged tracks
per unit h-
(pT > 0.5 GeV/c, |h| < 1)
dPTsum/dhd
Scalar pT sum of charged
particles per unit h-
(pT > 0.5 GeV/c, |h| < 1)
Scalar pT sum of “good” charged tracks
per unit h-
(pT > 0.5 GeV/c, |h| < 1)
<pT>
Average pT of charged particles
(pT > 0.5 GeV/c, |h| < 1)
Average pT of “good” charged tracks
(pT > 0.5 GeV/c, |h| < 1)
PTmax
Maximum pT charged particle
(pT > 0.5 GeV/c, |h| < 1)
PTmax = 0 for no charged
particle
Maximum pT “good” charged tracks
(pT > 0.5 GeV/c, |h| < 1)
PTmax = 0 for no “good” charged track
dETsum/dhd
Scalar ET sum of all particles
per unit h-
(all pT, |h| < 1)
Scalar ET sum of all calorimeter towers
per unit h-
(ET > 0.1 GeV, |h| < 1)
PTsum/ETsum
Scalar pT sum of charged
particles
(pT > 0.5 GeV/c, |h| < 1)
divided by the scalar ET sum of
all particles (all pT, |h| < 1)
Scalar pT sum of “good” charged tracks
(pT > 0.5 GeV/c, |h| < 1)
divided by the scalar ET sum of
calorimeter towers (ET > 0.1 GeV, |h| < 1)
Rick Field – Florida/CDF/CMS
Page 6

“Toward”
“Transverse”
“Transverse”
“Away”
Jet #1 Direction

“Toward”
“Transverse”
“Transverse”
“Away”
Jet #2 Direction
“Back-to-Back”
MPI & UE - DESY
May 18-19, 2007
“TransMAX/MIN” Nchg Density
PYTHIA Tune A vs HERWIG
“Leading Jet”
“Back-to-Back”
Jet #1 Direction
Jet #1 Direction
“TransMIN”
“Away”
CDF Run 2 Preliminary
“Toward”
“TransMAX”
“TransMIN”
“Away”
"Transverse" Charged Density
“TransMAX”
1.4


“Toward”
"TransMAX" Charged Particle Density: dN/dhd
"Leading Jet"
data corrected to particle level
1.2
1.0
"Back-to-Back"
0.8
0.6
HW
PY Tune A
MidPoint R = 0.7 |h(jet#1) < 2
0.4
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
1.96 TeV
Jet #2 Direction
0.2
 Shows the charged particle density,
50
100
150
200
250
300
350
400
450
PT(jet#1) (GeV/c)
"TransMIN" Charged Particle Density: dN/dhd
0.6
CDF Run 2 Preliminary
"Transverse" Charged Density
dNchg/dhd, in the “transMAX” and
“transMIN” region (pT > 0.5 GeV/c,
|h| < 1) versus PT(jet#1) for “Leading
Jet” and “Back-to-Back” events.
 Compares the (corrected) data with
PYTHIA Tune A (with MPI) and
HERWIG (without MPI) at the
particle level.
0
MidPoint R = 0.7 |h(jet#1) < 2
data corrected to particle level
0.5
1.96 TeV
HW
0.4
"Leading Jet"
0.3
0.2
"Back-to-Back"
0.1
PY Tune A
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
0
50
100
150
200
250
300
350
400
450
PT(jet#1) (GeV/c)
MPI & UE - DESY
May 18-19, 2007
Rick Field – Florida/CDF/CMS
Page 7
CDF Run 1 PT(Z)
PYTHIA 6.2 CTEQ5L
UE Parameters
Tune A
Tune A25
Tune A50
MSTP(81)
1
1
1
MSTP(82)
4
4
4
PARP(82)
2.0 GeV
2.0 GeV
2.0 GeV
PARP(83)
0.5
0.5
0.5
PARP(84)
0.4
0.4
0.4
PARP(85)
0.9
0.9
0.9
PARP(86)
0.95
0.95
0.95
1.8 TeV
1.8 TeV
1.8 TeV
PARP(90)
0.25
0.25
0.25
PARP(67)
4.0
4.0
4.0
MSTP(91)
1
1
1
PARP(91)
1.0
2.5
5.0
PARP(93)
5.0
15.0
25.0
s = 1.0
CDF Run 1 Data
PYTHIA Tune A
PYTHIA Tune A25
PYTHIA Tune A50
s = 2.5
0.08
CDF Run 1
published
1.8 TeV
s = 5.0
Normalized to 1
0.04
0.00
0
ISR Parameter PARP(89)
Z-Boson Transverse Momentum
0.12
PT Distribution 1/N dN/dPT
Parameter
2
4
6
8
10
12
14
16
18
Z-Boson PT (GeV/c)
 Shows the Run 1 Z-boson pT distribution
(<pT(Z)> ≈ 11.5 GeV/c) compared with PYTHIA
Tune A (<pT(Z)> = 9.7 GeV/c), Tune A25
(<pT(Z)> = 10.1 GeV/c), and
Tune A50
(<pT(Z)> = 11.2 GeV/c).
Vary the intrensic KT!
Intrensic KT
MPI & UE - DESY
May 18-19, 2007
20
Rick Field – Florida/CDF/CMS
Page 8
CDF Run 1 PT(Z)
PYTHIA 6.2 CTEQ5L
Tune used by the
CDF-EWK group!
Z-Boson Transverse Momentum
Parameter
Tune A
Tune AW
UE Parameters MSTP(81)
1
1
MSTP(82)
4
4
PARP(82)
2.0 GeV
2.0 GeV
PARP(83)
0.5
0.5
PARP(84)
0.4
0.4
PARP(85)
0.9
0.9
PARP(86)
0.95
0.95
PARP(89)
1.8 TeV
1.8 TeV
PARP(90)
0.25
0.25
PARP(62)
1.0
1.25
PARP(64)
1.0
0.2
PARP(67)
4.0
4.0
MSTP(91)
1
1
PARP(91)
1.0
2.1
PARP(93)
5.0
15.0
PT Distribution 1/N dN/dPT
0.12
CDF Run 1 Data
PYTHIA Tune A
PYTHIA Tune AW
published
0.08
1.8 TeV
Normalized to 1
0.04
0.00
0
ISR Parameters
CDF Run 1
2
4
6
8
10
12
14
16
18
Z-Boson PT (GeV/c)
 Shows the Run 1 Z-boson pT distribution (<pT(Z)>
≈ 11.5 GeV/c) compared with PYTHIA Tune A
(<pT(Z)> = 9.7 GeV/c), and PYTHIA Tune AW
(<pT(Z)> = 11.7 GeV/c).
Effective Q cut-off, below which space-like showers are not evolved.
Intrensic KT
The Q2 = kT2 in as for space-like showers is scaled by PARP(64)!
MPI & UE - DESY
May 18-19, 2007
20
Rick Field – Florida/CDF/CMS
Page 9
Jet-Jet Correlations (DØ)
Jet#1-Jet#2  Distribution
 Jet#1-Jet#2
 MidPoint Cone Algorithm (R = 0.7, fmerge = 0.5)
 L = 150 pb-1 (Phys. Rev. Lett. 94 221801 (2005))
 Data/NLO agreement good. Data/HERWIG agreement
good.
 Data/PYTHIA agreement good provided PARP(67) =
1.0→4.0 (i.e. like Tune A, best fit 2.5).
MPI & UE - DESY
May 18-19, 2007
Rick Field – Florida/CDF/CMS
Page 10
CDF Run 1 PT(Z)
PYTHIA 6.2 CTEQ5L
Z-Boson Transverse Momentum
Parameter
Tune DW
Tune AW
UE Parameters MSTP(81)
1
1
MSTP(82)
4
4
PARP(82)
1.9 GeV
2.0 GeV
PARP(83)
0.5
0.5
PARP(84)
0.4
0.4
PARP(85)
1.0
0.9
PARP(86)
1.0
0.95
PARP(89)
1.8 TeV
1.8 TeV
PARP(90)
0.25
0.25
PARP(62)
1.25
1.25
PARP(64)
0.2
0.2
PARP(67)
2.5
4.0
MSTP(91)
1
1
PARP(91)
2.1
2.1
PARP(93)
15.0
15.0
PT Distribution 1/N dN/dPT
0.12
CDF Run 1 Data
PYTHIA Tune DW
HERWIG
Intrensic KT
published
0.08
1.8 TeV
Normalized to 1
0.04
0.00
0
ISR Parameters
CDF Run 1
2
4
6
8
10
12
14
16
18
20
Z-Boson PT (GeV/c)
 Shows the Run 1 Z-boson pT distribution (<pT(Z)>
≈ 11.5 GeV/c) compared with PYTHIA Tune DW,
and HERWIG.
Tune DW uses D0’s perfered value of PARP(67)!
Tune DW has a lower value of PARP(67) and slightly more MPI!
MPI & UE - DESY
May 18-19, 2007
Rick Field – Florida/CDF/CMS
Page 11
“Transverse” Nchg Density
ISR Parameter
Intrensic KT
Parameter
Tune AW
Tune DW
Tune BW
MSTP(81)
1
1
1
MSTP(82)
4
4
4
PARP(82)
2.0 GeV
1.9 GeV
1.8 GeV
PARP(83)
0.5
0.5
0.5
PARP(84)
0.4
0.4
0.4
PARP(85)
0.9
1.0
1.0
PARP(86)
0.95
1.0
1.0
PARP(89)
1.8 TeV
1.8 TeV
1.8 TeV
PARP(90)
0.25
0.25
0.25
PARP(62)
1.25
1.25
1.25
PARP(64)
0.2
0.2
0.2
PARP(67)
4.0
2.5
1.0
MSTP(91)
1
1
1
PARP(91)
2.5
2.5
2/5
PARP(93)
15.0
15.0
15.0
Three different amounts of ISR!
MPI & UE - DESY
May 18-19, 2007
"Transverse" Charged
Charged Particle
Particle Density:
Density: dN/dhd
dN/dhd
"Transverse"
1.0
1.0
"Transverse"
"Transverse"Charged
ChargedDensity
Density
UE Parameters
Three different amounts of MPI!
PYTHIA 6.2 CTEQ5L
RDF Preliminary
Preliminary
RDF
PY Tune BW
generator level
level
generator
0.8
0.8
PYPY
Tune
DW
Tune
DW
PY-ATLAS
PY Tune A
0.6
0.6
0.4
0.4
PY Tune AW
HERWIG
HERWIG
1.96 TeV
TeV
1.96
0.2
0.2
Leading Jet
Jet (|h|<2.0)
(|h|<2.0)
Leading
Charged Particles
Particles (|h|<1.0,
(|h|<1.0, PT>0.5
PT>0.5 GeV/c)
GeV/c)
Charged
0.0
0.0
00
50
50
100
100
150
150
200
200
250
250
300
300
350
350
400
400
450
450
500
500
PT(particle jet#1)
jet#1) (GeV/c)
(GeV/c)
PT(particle
 Shows the “transverse” charged particle
density, dN/dhd, versus PT(jet#1) for “leading
jet” events at 1.96 TeV for PYTHIA Tune A,
Tune AW, Tune DW, Tune BW, and HERWIG
(without MPI).
 Shows the “transverse” charged particle
density, dN/dhd, versus PT(jet#1) for “leading
jet” events at 1.96 TeV for Tune DW, ATLAS,
and HERWIG (without MPI).
Rick Field – Florida/CDF/CMS
Page 12
“Transverse” PTsum Density
Three different amounts of MPI!
PYTHIA 6.2 CTEQ5L
UE Parameters
ISR Parameter
Intrensic KT
Tune AW
Tune DW
Tune BW
MSTP(81)
1
1
1
MSTP(82)
4
4
4
PARP(82)
2.0 GeV
1.9 GeV
1.8 GeV
PARP(83)
0.5
0.5
0.5
PARP(84)
0.4
0.4
0.4
PARP(85)
0.9
1.0
1.0
PARP(86)
0.95
1.0
1.0
PARP(89)
1.8 TeV
1.8 TeV
1.8 TeV
PARP(90)
0.25
0.25
0.25
PARP(62)
1.25
1.25
1.25
PARP(64)
0.2
0.2
0.2
PARP(67)
4.0
2.5
1.0
MSTP(91)
1
1
1
PARP(91)
2.5
2.5
2/5
PARP(93)
15.0
15.0
15.0
Three different amounts of ISR!
MPI & UE - DESY
May 18-19, 2007
"Transverse" PTsum Density: dPT/dhd
"Transverse" PTsum
PTsum Density
Density (GeV/c)
(GeV/c)
"Transverse"
Parameter
1.6
RDF Preliminary
generator level
1.2
PY Tune BW
PY Tune A
PY-ATLAS
0.8
PY Tune AW
PY Tune DW
1.96 TeV
0.4
HERWIG
Leading Jet (|h|<2.0)
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
HERWIG
0.0
0
50
100
150
200
250
300
350
400
450
PT(particle jet#1) (GeV/c)
 Shows the “transverse” charged PTsum
density, dPT/dhd, versus PT(jet#1) for
“leading jet” events at 1.96 TeV for PYTHIA
Tune A, Tune AW, Tune DW, Tune BW, and
HERWIG (without MPI).
 Shows the “transverse” charged PTsum
density, dPT/dhd, versus PT(jet#1) for
“leading jet” events at 1.96 TeV for Tune DW,
ATLAS, and HERWIG (without MPI).
Rick Field – Florida/CDF/CMS
Page 13
500
PYTHIA 6.2 Tunes
s(MPI) at 1.96 TeV
s(MPI) at 14 TeV
Tune A
309.7 mb
484.0 mb
Tune DW
351.7 mb
549.2 mb
Tune DWT
351.7 mb
829.1 mb
324.5 mb
CDF Run 2 Data!
768.0 mb
PYTHIA 6.2 CTEQ5L
Parameter
Tune A
Tune DW
Tune DWT
ATLAS
MSTP(81)
1
1
1
1
MSTP(82)
4
PARP(82)
2.0 GeV
4
1.7GeV
1.9
PARP(83)
0.5
"Leading Jet"
"Transverse"
Charged
Particle
Average
pT
"Transverse"
Charged
Particle
Density:
dN/dhd
"Transverse"
PTsum
Density:
dPT/dhd
0.5 data corrected
0.5 to particle level
0.5
1.5
0.4
0.5
PY Tune0.4
A, DW
PARP(85)
0.9
PARP(86)
0.95
PARP(89)
1.8 TeV
PARP(90)
0.25
PARP(62)
1.0
PARP(64)
1.0
0.2
PARP(67)
4.0
MSTP(91)
1
0.72.5
0
1
1.0
1.3
1.0
1.8
1.1 TeV
0.25
1.0
0.33
1.0
0.66
1.96 TeV
1.0 TeV
0.16
0.16
1.25
1.0
1.25
0.9
1.96 TeV
0.2
2.5
50
1
100
HERWIG
1.0
1.0
150
1
PARP(91)
1.0
2.1
2.1
1.0
PARP(93)
5.0
15.0
15.0
5.0
Identical to DW at 1.96 TeV but uses
ATLAS extrapolation to the LHC!
MPI & UE - DESY
May 18-19, 2007
ATLAS
1.8 GeV
"Transverse"
Charged
PTDensity
(GeV/c)
"Transverse"
Charged
"Transverse"
PTsum
Density
(GeV/c)
0.4
1.9409 GeV
Charged Average PT
CDF Run 2 Preliminary
"Transverse" <PT> (GeV/c)
PARP(84)
4"Transverse"
4
1.6
1.0
1.5
RDF
RDFPreliminary
Preliminary
RDF
Preliminary
generator
generatorlevel
level
generator
level
0.8
1.2
1.3
PY Tune DW
PY Tune DW
0.6
PY Tune DW
PY Tune A
PY Tune A
PY-ATLAS
PY-ATLAS
0.8
1.1
PY-ATLAS
0.4
PY Tune A
MidPoint R = 0.7 |h(jet#1) <PY-ATLAS
2
1.96TeV
TeV
1.96
1.96 TeV
HERWIG
0.4
0.9
HERWIGPT>0.5 GeV/c)
Charged
Particles (|h|<1.0,
0.2
Leading
JetJet
(|h|<2.0)
Leading
(|h|<2.0)
Leading
Jet (|h|<2.0)
Charged
Particles
(|h|<1.0,
PT>0.5
GeV/c)
Charged
Particles
(|h|<1.0,
PT>0.5
GeV/c)
Charged
Particles
(|h|<1.0,
PT>0.5
GeV/c)
HERWIG
0.0
0.0
200 0.7 250
00
0
50
50
50
300
100
100
100
PT(jet#1) (GeV/c)
350
150
150
150
400
200
200
200
250
250
250
450
300
300
300
350
350
350
400
400
400
450
450
450
500
500
500
PT(particle
jet#1)
PT(particle jet#1)
jet#1) (GeV/c)
(GeV/c)
PT(particle
(GeV/c)
Shows
Showsthe
the“transverse”
“transverse”charged
chargedPTsum
particledensity,

Shows
the
“transverse”
charged
average
pdensity,

T,
dN/dhd,
versus
PPTT(jet#1)
“leading
versus
PT(jet#1)
“leading
jet”
eventsjet”
at 1.96
dPT/dhd,
versusfor
(jet#1) for
for
“leading
jet”
events
1.96A,
TeV
forATLAS,
TuneA,
A,and
DW,HERWIG
ATLAS,and
and
TeV
foratatTune
DW,
events
1.96
TeV
for
Tune
DW,
ATLAS,
HERWIG
(withoutMPI).
MPI).
(without
MPI).
HERWIG
(without
Rick Field – Florida/CDF/CMS
Page 14
Use LO as
with L = 192 MeV!
UE Parameters
ISR Parameter
New PYTHIA 6.2 Tunes
Parameter
Tune DW
Tune D6
Tune QW
Tune QK
PDF
CTEQ5L
CTEQ6L
CTEQ6.1
CTEQ6.1
MSTP(2)
1
1
1
1
MSTP(33)
0
0
0
1
PARP(31)
1.0
1.0
1.0
1.8
MSTP(81)
1
1
1
1
MSTP(82)
4
4
4
4
PARP(82)
1.9 GeV
1.8 GeV
1.1 GeV
1.9 GeV
PARP(83)
0.5
0.5
0.5
0.5
PARP(84)
0.4
0.4
0.4
0.4
PARP(85)
1.0
1.0
1.0
1.0
PARP(86)
1.0
1.0
1.0
1.0
PARP(89)
1.8 TeV
1.8 TeV
1.8 TeV
1.8 TeV
PARP(90)
0.25
0.25
0.25
0.25
PARP(62)
1.25
1.25
1.25
1.25
PARP(64)
0.2
0.2
0.2
0.2
PARP(67)
2.5
2.5
2.5
2.5
MSTP(91)
1
1
1
1
PARP(91)
2.1
2.1
2.1
2.1
PARP(93)
15.0
15.0
15.0
15.0
NLO Structure Function!
K-factor
(T. Sjostrand)
Tune A energy dependence!
Intrinsic KT
MPI & UE - DESY
May 18-19, 2007
Rick Field – Florida/CDF/CMS
Page 15
Use LO as
with L = 192 MeV!
UE Parameters
ISR Parameter
New PYTHIA 6.2 Tunes
Parameter
Tune DWT
ATLAS
Tune D6T
Tune QWT
Tune QKT
PDF
CTEQ5L
CTEQ5L
CTEQ6L
CTEQ6.1
CTEQ6.1
MSTP(2)
1
1
1
1
1
MSTP(33)
0
0
1
1
1
PARP(31)
1.0
1.0
1.0
1.0
1.8
MSTP(81)
1
1
1
1
1
MSTP(82)
4
4
4
4
4
PARP(82)
1.9409 GeV
1.8 GeV
1.8387 GeV
1.1237 GeV
1.9409 GeV
PARP(83)
0.5
0.5
0.5
0.5
0.5
PARP(84)
0.4
0.5
0.4
0.4
0.4
PARP(85)
1.0
0.33
1.0
1.0
1.0
PARP(86)
1.0
0.66
1.0
1.0
1.0
PARP(89)
1.96 TeV
1.0 TeV
1.96 TeV
1.96 TeV
1.96 TeV
PARP(90)
0.16
0.16
0.16
0.16
0.16
PARP(62)
1.25
1.0
1.25
1.25
1.25
PARP(64)
0.2
1.0
0.2
0.2
0.2
PARP(67)
2.5
1.0
2.5
2.5
2.5
MSTP(91)
1
1
1
1
1
PARP(91)
2.1
1.0
2.1
2.1
2.1
PARP(93)
15.0
5.0
15.0
15.0
15.0
NLO Structure Function!
K-factor
(T. Sjostrand)
ATLAS energy dependence!
Intrinsic KT
MPI & UE - DESY
May 18-19, 2007
Rick Field – Florida/CDF/CMS
Page 16
New PYTHIA 6.2 Tunes
1.96 TeV
"Transverse" Charged Particle Density: dN/dhd
1.0
"Transverse" Charged Density
PT0(MPI)
GeV
s(MPI)
mb
PT0(MPI)
GeV
s(MPI)
mb
Tune DW
1.9409
351.7
3.1730
549.2
Tune DWT
1.9409
351.7
2.6091
829.1
ATLAS
2.0046
324.5
2.7457
768.0
Tune D6
1.8387
306.3
3.0059
546.1
Tune D6T
1.8387
306.3
2.5184
786.5
Tune QK
1.9409
259.5
3.1730
422.0
Tune QKT
1.9409
259.5
2.6091
588.0
PY Tune DW
RDF Preliminary
generator level
0.8
0.6
PY Tune D6
0.4
PY Tune QK
1.96 TeV
14 TeV
0.2
Leading Jet (|h|<2.0)
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
0
50
100
150
200
250
300
350
400
450
500
PT(particle jet#1) (GeV/c)
"Transverse" PTsum Density (GeV/c)
"Transverse" PTsum Density: dPT/dhd
1.6
RDF Preliminary
PY Tune QK
 Average charged particle density and
PTsum density in the “transverse”
region (pT > 0.5 GeV/c, |h| < 1) versus
PT(jet#1) at 1.96 TeV for PY Tune DW,
Tune D6, and Tune QK.
generator level
1.2
PY Tune DW
PY Tune D6
0.8
1.96 TeV
0.4
Leading Jet (|h|<2.0)
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
0
50
100
150
200
250
300
350
400
450
500
PT(particle jet#1) (GeV/c)
MPI & UE - DESY
May 18-19, 2007
Rick Field – Florida/CDF/CMS
Page 17
New PYTHIA 6.2 Tunes
1.96 TeV
"Transverse" Charged Particle Density: dN/dhd
"Transverse" Charged Density
2.5
PT0(MPI)
GeV
s(MPI)
mb
PT0(MPI)
GeV
s(MPI)
mb
Tune DW
1.9409
351.7
3.1730
549.2
Tune DWT
1.9409
351.7
2.6091
829.1
ATLAS
2.0046
324.5
2.7457
768.0
14 TeV
Tune D6
1.8387
306.3
3.0059
546.1
Leading Jet (|h|<2.0)
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
Tune D6T
1.8387
306.3
2.5184
786.5
Tune QK
1.9409
259.5
3.1730
422.0
Tune QKT
1.9409
259.5
2.6091
588.0
PY Tune DWT
RDF Preliminary
generator level
2.0
1.5
PY Tune QKT
PY Tune D6T
1.0
0.5
0.0
0
250
500
750
14 TeV
1000
1250
1500
1750
2000
PT(particle jet#1) (GeV/c)
"Transverse" PTsum Density (GeV/c)
"Transverse" PTsum Density: dPT/dhd
8.0
 Average charged particle density and
PTsum density in the “transverse”
region (pT > 0.5 GeV/c, |h| < 1) versus
PT(jet#1) at 14 TeV for PY Tune DWT,
Tune D6T, and Tune QKT.
PY Tune DWT
RDF Preliminary
generator level
6.0
PY Tune QKT
4.0
14 TeV
2.0
Leading Jet (|h|<2.0)
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
PY Tune D6T
0.0
0
250
500
750
1000
1250
1500
1750
2000
PT(particle jet#1) (GeV/c)
MPI & UE - DESY
May 18-19, 2007
Rick Field – Florida/CDF/CMS
Page 18
New PYTHIA 6.2 Tunes
14 TeV (pT > 0.5 GeV/c, |h| < 1)
Charged Particle Density: dN/dh
Charged Particle Density
4
<Nchg>
<PTsum>
(GeV/c)
<PT>
(GeV/c)
Tune DWT
6.268
7.091
1.131
Tune D6T
5.743
6.467
1.126
Tune QKT
5.361
6.115
0.982
pyDWT LHC
pyD6T LHC
pyQKT LHC
Min-Bias
(Hard Core)
3
No Trigger
MSTJ(22)=1
14 TeV
2
1
Charged Particles (PT > 0.5 GeV/c)
Numbers for pT > 0.5 GeV/c, |h| < 1.
0
-10
-8
-6
-4
-2
0
2
4
6
8
10
PseudoRapidity h
 PseudoRapidity distribution, dN/dh, for charged
particles with pT > 0.5 GeV/c at 14 TeV for PY
Tune DWT, Tune D6T, and Tune QKT. Note this is
“hard core” (i.e. MSEL=1, PT(hard) = 0) with no
trigger and with only stable particles (i.e.
MSTJ(22)=1). Tune D6T uses CTEQ6L (i.e.
LHAPDF = 10042) and Tune QKT uses
CTEQ6.1M (i.e. LHAPDF = 10100 or 10150 which
are the same).
MPI & UE - DESY
May 18-19, 2007
We have CTEQ6L Tune D6T
and
NLO PDF Tune QKT!
Rick Field – Florida/CDF/CMS
Page 19
Summary
Outgoing Parton
“Minumum Bias” Collisions
Tevatron
LHC
PT(hard)
Initial-State Radiation
Proton
AntiProton
Proton
AntiProton
Underlying Event
Outgoing Parton
Underlying Event
Final-State
Radiation
 PYTHIA Tune DW is very similar to Tune A except that it fits the CDF PT(Z) distribution
and it uses the DØ prefered value of PARP(67) = 2.5 (determined from the dijet 
We need to decide whether to
distribution).
use NLO PDF’s (i.e. Tune QWT) or
whether
to stick
with
 PYTHIA Tune DWT is identical
to Tune
DW at
1.96LO
TeVPDF’s
but uses the ATLAS energy
extrapolation to the LHC (i.e.
PARP(90)
= 0.16).
(i.e.
Tune DWT
or Tune D6T)!
wesimilar
need to
develop
a procedure
 PYTHIA Tune D6 andAnd
D6T are
to Tune
DW and
DWT, respectively, but use
to validate the Tunes!
CTEQ6L (i.e. LHAPDF = 10042).
 PYTHIA Tune QK and QKT uses the NLO PDF CTEQ6.1M (i.e. LHAPDF = 10100 or
10150 which are the same) and use the “K-factor” to get the right amount of MPI.
I prefer QK and QKT over QW and QWT!
MPI & UE - DESY
May 18-19, 2007
Rick Field – Florida/CDF/CMS
Page 20