ICHEP06
The Underlying Event at CDF
Rick Field
University of Florida
(for the CDF Collaboration)
Outgoing Parton
PT(hard)
Initial-State Radiation
Proton
AntiProton
Underlying Event
Underlying Event
CDF Run 2
Outgoing Parton
Final-State
Radiation
Tuning the Models & Extrapolating to the LHC
ICHEP06
July 28, 2006
Rick Field – Florida/CDF
Page 1
QCD Monte-Carlo Models:
High Transverse Momentum Jets
Hard Scattering
Hard Scattering
Initial-State Radiation
Initial-State Radiation
Outgoing Parton
PT(hard)
Outgoing Parton
PT(hard)
Proton
“Hard Scattering” Component
AntiProton
Underlying Event
Final-State Radiation
Underlying Event
Outgoing Parton
Proton
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).
ICHEP06
July 28, 2006
Rick Field – Florida/CDF
Page 2
QCD Monte-Carlo Models:
High Transverse Momentum Jets
Hard Scattering
Hard Scattering
Initial-State Radiation
“Jet”
Initial-State Radiation
Outgoing Parton
PT(hard)
Outgoing Parton
“Jet” PT(hard)
Proton
“Hard Scattering” Component
AntiProton
Underlying Event
Final-State Radiation
Underlying Event
Outgoing Parton
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).
 Of course the outgoing colored partons fragment into hadron “jet” and inevitably “underlying event”
observables receive contributions from initial and final-state radiation.
ICHEP06
July 28, 2006
Rick Field – Florida/CDF
Page 3
QCD Monte-Carlo Models:
High Transverse Momentum Jets
Hard Scattering
Hard Scattering
Initial-State Radiation
“Jet”
Proton
Initial-State Radiation
Outgoing Parton
PT(hard)
Outgoing Parton
“Jet” PT(hard)
“Hard Scattering” Component
AntiProton
Underlying Event
Underlying Event
Final-State Radiation
Outgoing Parton
Studying the “underlying event” teaches us not
only about the beam-beam remnants
Protonand
“Jet”
Final-State Radiation
Outgoing Parton multiple-parton interactions, but also about
initial and final-state radiation
“Underlying Event”
and hadronization.
Underlying Event
AntiProton
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).
 Of course the outgoing colored partons fragment into hadron “jet” and inevitably “underlying event”
observables receive contributions from initial and final-state radiation.
ICHEP06
July 28, 2006
Rick Field – Florida/CDF
Page 4
Evolution of Charged Jets
“Underlying Event”
Charged Particle  Correlations
PT > 0.5 GeV/c |h| < 1
Charged Jet #1
Direction
“Transverse” region
very sensitive to the
“underlying event”!
Look at the charged
particle density in the
“transverse” region!
2p
“Toward-Side” Jet

“Toward”
CDF Run 1 Analysis
Away Region
Charged Jet #1
Direction

Transverse
Region
“Toward”
“Transverse”

Leading
Jet
“Transverse”
Toward Region
“Transverse”
“Transverse”
Transverse
Region
“Away”
“Away”
Away Region
“Away-Side” Jet
0
-1
h
+1
 Look at charged particle correlations in the azimuthal angle  relative to the leading charged
particle jet.
 Define || < 60o as “Toward”, 60o < || < 120o as “Transverse”, and || > 120o as “Away”.
 All three regions have the same size in h- space, hx = 2x120o = 4p/3.
ICHEP06
July 28, 2006
Rick Field – Florida/CDF
Page 5
Run 1 PYTHIA Tune A
CDF Default!
PYTHIA 6.206 CTEQ5L
"Transverse" Charged Particle Density: dN/dhd
Tune B
Tune A
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(67)
1.0
4.0
New PYTHIA default
(less initial-state radiation)
ICHEP06
July 28, 2006
1.00
"Transverse" Charged Density
Parameter
CDF Preliminary
PYTHIA 6.206 (Set A)
PARP(67)=4
data uncorrected
theory corrected
0.75
Run 1 Analysis
0.50
0.25
CTEQ5L
PYTHIA 6.206 (Set B)
PARP(67)=1
1.8 TeV |h|<1.0 PT>0.5 GeV
0.00
0
5
10
15
20
25
30
35
40
45
50
PT(charged jet#1) (GeV/c)
 Plot shows the “transverse” charged particle density
versus PT(chgjet#1) compared to the QCD hard
scattering predictions of two tuned versions of
PYTHIA 6.206 (CTEQ5L, Set B (PARP(67)=1) and
Set A (PARP(67)=4)).
Old PYTHIA default
(more initial-state radiation)
Rick Field – Florida/CDF
Page 6
“Transverse”
Charged Particle Density
“Transverse” region as
defined by the leading
“charged particle jet”
"Transverse" Charged Particle Density: dN/dhd
“Toward”
“Transverse”
“Transverse”
"Transverse" Charged Density
1.25
Charged Particle Jet #1
Direction

CDF Preliminary
1.00
CDF Run 1 Published
CDF Run 2 Preliminary
PYTHIA Tune A
data uncorrected
theory corrected
0.75
0.50
0.25
|h|<1.0 PT>0.5 GeV/c
“Away”
0.00
0
10
20
30
40
50
60
70
80
90
100 110 120 130 140 150
PT(charged jet#1) (GeV/c)
Excellent agreement
between Run 1 and 2!
 Shows the data on the average “transverse” charge particle density (|h|<1, pT>0.5 GeV) as
a function of the transverse momentum of the leading charged particle jet from Run 1.
 Compares the Run 2 data (Min-Bias, JET20, JET50, JET70, JET100) with Run 1.

The errors on the (uncorrected) Run 2 data include both statistical
and Tune
correlated
PYTHIA
A was tuned to fit
the “underlying event” in Run I!
systematic uncertainties.
Shows the prediction of PYTHIA Tune A at 1.96 TeV after detector simulation (i.e. after
CDFSIM).
ICHEP06
July 28, 2006
Rick Field – Florida/CDF
Page 7
The “Transverse” Regions
as defined by the Leading Jet
Jet #1 Direction
“Transverse” region is
very sensitive to the
“underlying event”!
Charged Particle  Correlations
pT > 0.5 GeV/c |h| < 1
2p
Look at the charged
particle density in the
“transverse” region!
Away Region
“Toward-Side” Jet
Jet #1 Direction

“Toward”
“Transverse”
“Transverse”
“Away”
Transverse
Region 1

“Toward”
“Trans 1”

Leading
Jet
“Trans 2”
Toward Region
Transverse
Region 2
“Away”
Away Region
“Away-Side” Jet
0
-1
h
+1
 Look at charged particle correlations in the azimuthal angle  relative to the leading

calorimeter jet (JetClu R = 0.7, |h| < 2).
o
o
o
o
o
Define || < 60 as “Toward”, 60 < - < 120 and 60 <  < 120 as “Transverse 1” and
o
“Transverse 2”, and || > 120 as “Away”. Each of the two “transverse” regions have
o
area h = 2x60 = 4p/6. The overall “transverse” region is the sum of the two
o
transverse regions (h = 2x120 = 4p/3).
ICHEP06
July 28, 2006
Rick Field – Florida/CDF
Page 8
Charged Particle Density  Dependence
Refer to this as a
“Leading Jet” event
Jet #1 Direction
Charged Particle Density: dN/dhd

10.0
CDF Preliminary
Subset
“Transverse”
“Transverse”
“Away”
Refer to this as a
“Back-to-Back” event
Jet #1 Direction

“Toward”
“Transverse”
“Transverse”
“Away”
Charged Particle Density
“Toward”
30 < ET(jet#1) < 70 GeV
Back-to-Back
Leading Jet
Min-Bias
data uncorrected
"Transverse"
Region
1.0
Jet#1
Charged Particles
(|h|<1.0, PT>0.5 GeV/c)
0.1
0
30
60
90
120
150
180
210
240
270
300
330
360
 (degrees)
Jet #2 Direction
 Look at the “transverse” region as defined by the leading jet (JetClu R = 0.7, |h| < 2) or by the
leading two jets (JetClu R = 0.7, |h| < 2). “Back-to-Back” events are selected to have at least
two jets with Jet#1 and Jet#2 nearly “back-to-back” (12 > 150o) with almost equal
transverse energies (ET(jet#2)/ET(jet#1) > 0.8) and with ET(jet#3) < 15 GeV.
 Shows the  dependence of the charged particle density, dNchg/dhd, for charged
particles in the range pT > 0.5 GeV/c and |h| < 1 relative to jet#1 (rotated to 270o) for 30
< ET(jet#1) < 70 GeV for “Leading Jet” and “Back-to-Back” events.
ICHEP06
July 28, 2006
Rick Field – Florida/CDF
Page 9
“Transverse” PTsum Density vs ET(jet#1)
Jet #1 Direction

“Toward”
“Transverse”
“Transverse”
“Away”
“Back-to-Back”
Jet #1 Direction

“Toward”
“Transverse”
"AVE Transverse" PTsum Density: dPT/dhd
1.4
“Transverse”
"Transverse" PTsum Density (GeV/c)
“Leading Jet”
uncorrected
datadata
uncorrected
theory + CDFSIM
PY Tune A
1.0
Hard Radiation!
0.8
0.6
0.4
Back-to-Back
HW
0.2
1.96 TeV
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
0
50
“Away”
Jet #2 Direction
Leading Jet
CDF Run
2 Preliminary
Preliminary
1.2
100
150
200
250
ET(jet#1) (GeV)
Min-Bias
0.24 GeV/c per unit h-
 Shows the average charged PTsum density, dPTsum/dhd, in the “transverse” region (pT
> 0.5 GeV/c, |h| < 1) versus ET(jet#1) for “Leading Jet” and “Back-to-Back” events.
 Compares the (uncorrected) data with PYTHIA Tune A and HERWIG (without MPI)
after CDFSIM.
ICHEP06
July 28, 2006
Rick Field – Florida/CDF
Page 10
Latest CDF Run 2
“Underlying Event” Results
Jet #1 Direction

“Toward”
“Trans 1”
The “underlying event” consists of the
“beam-beam remnants” and possible
multiple parton interactions, but
inevitably received contributions from
initial and final-state radiation.
Outgoing Parton
PT(hard)
Initial-State Radiation
“Trans 2”
Proton
AntiProton
Underlying Event
Underlying Event
“Away”
“Transverse” region is
very sensitive to the
“underlying event”!
Outgoing Parton
Final-State
Radiation
Latest CDF Run 2 Results (L = 385 pb-1) :
 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.
ICHEP06
July 28, 2006
Rick Field – Florida/CDF
Page 11
“TransMAX/MIN” PTsum Density
PYTHIA Tune A vs HERWIG
Jet #1 Direction
“TransMAX”
“TransMIN”
“Away”
3.0


“Toward”
"TransMAX" Charged PTsum Density: dPT/dhd
Jet #1 Direction
"Transverse" PTsum Density (GeV/c)
“Leading Jet”
PYTHIA Tune A does a fairly
good job fitting the PTsum
density in the “transverse”
region!
“Back-to-Back”
HERWIG does a poor job!
“Toward”
“TransMAX”
“TransMIN”
“Away”
Jet #2 Direction
CDF Run 2 Preliminary
data corrected to particle level
2.5
"Leading Jet"
1.96 TeV
2.0
PY Tune A
1.5
"Back-to-Back"
1.0
MidPoint R = 0.7 |h(jet#1) < 2
0.5
HW
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
0
50
100
150
ICHEP06
July 28, 2006
300
350
400
450
"TransMIN" Charged PTsum Density: dPT/dhd
0.6
"Transverse" PTsum Density (GeV/c)

250
PT(jet#1) (GeV/c)
 Shows the charged particle PTsum
density, dPTsum/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.
200
CDF Run 2 Preliminary
MidPoint R = 0.7 |h(jet#1) < 2
data corrected to particle level
0.5
1.96 TeV
"Leading Jet"
0.4
0.3
"Back-to-Back"
0.2
0.1
PY Tune A
HW
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
0
50
Rick Field – Florida/CDF
100
150
200
250
300
350
400
450
PT(jet#1) (GeV/c)
Page 12
CDF Run 1 PT(Z)
PYTHIA 6.2 CTEQ5L
Tune used by the
CDF-EWK group!
Z-Boson Transverse Momentum
UE Parameters
ISR Parameters
Parameter
Tune A
Tune AW
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
CDF Run 1
published
0.08
1.8 TeV
Normalized to 1
0.04
0.00
0
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)!
ICHEP06
July 28, 2006
20
Rick Field – Florida/CDF
Page 13
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).
ICHEP06
July 28, 2006
Rick Field – Florida/CDF
Page 14
CDF Run 1 PT(Z)
PYTHIA 6.2 CTEQ5L
Z-Boson Transverse Momentum
UE Parameters
ISR Parameters
Parameter
Tune DW
Tune AW
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
Intrensic KT
PT Distribution 1/N dN/dPT
0.12
CDF Run 1 Data
PYTHIA Tune DW
HERWIG
CDF Run 1
published
0.08
1.8 TeV
Normalized to 1
0.04
0.00
0
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!
ICHEP06
July 28, 2006
Rick Field – Florida/CDF
Page 15
CDF Run 1 PT(Z)
PYTHIA 6.2 CTEQ5L
Z-Boson Transverse Momentum
1.0E+00
ISR Parameters
Tune DW
Tune AW
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
Parameter
UE Parameters
CDF Run 1 Data
PYTHIA Tune DW
1.0E-01
CDF Run 1
published
1.8 TeV
1.0E-02
Normalized to 1
1.0E-03
1.0E-04
Also fits the high pT tail!
1.0E-05
0
10
20
30
40
50
60
70
80
90
100
Z-Boson PT (GeV/c)
Intrensic KT
 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!
ICHEP06
July 28, 2006
Rick Field – Florida/CDF
Page 16
PYTHIA 6.2 Tunes
s(MPI) at 1.96 TeV
s(MPI) at 14 TeV
Tune A
309.7 mb
484.0 mb
PYTHIA 6.2 CTEQ5L
Parameter
Tune A
Tune DW
Tune DWT
ATLAS
MSTP(81)
1
1
1
1
Tune DW
351.7 mb
549.2 mb
MSTP(82)
4
4
4
4
Tune DWT
351.7 mb
829.1 mb
PARP(82)
2.0 GeV
1.9 GeV
1.9409 GeV
1.8 GeV
ATLAS
324.5 mb
768.0 mb
PARP(83)
0.5
0.5
0.5
0.5
PARP(84)
0.4
0.4
0.4
0.5
PARP(85)
0.9
1.0
1.0
0.33
PARP(86)
0.95
1.0
1.0
0.66
PARP(89)
1.8 TeV
1.8 TeV
1.96 TeV
1.0 TeV
PARP(90)
0.25
0.25
0.16
0.16
"Transverse" Charged Particle Density: dN/dhd
PARP(62)
1.0
1.25
1.25
1.0
PARP(64)
1.0
0.2
0.2
1.0
PARP(67)
4.0
2.5
2.5
1.0
MSTP(91)
1
1
1
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!
ICHEP06
July 28, 2006
"Transverse" Charged Density
1.0
PY Tune DW
RDF Preliminary
generator level
0.8
0.6
PY-ATLAS
PY Tune A
0.4
HERWIG
1.96 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)
 Shows the “transverse” charged particle density,
dN/dhd, versus PT(jet#1) for “leading jet”
events at 1.96 TeV for Tune A, DW, ATLAS, and
HERWIG (without MPI).
Rick Field – Florida/CDF
Page 17
PYTHIA 6.2 Tunes
s(MPI) at 1.96 TeV
s(MPI) at 14 TeV
Tune A
309.7 mb
484.0 mb
PYTHIA 6.2 CTEQ5L
Parameter
Tune A
Tune DW
Tune DWT
ATLAS
MSTP(81)
1
1
1
1
Tune DW
351.7 mb
549.2 mb
MSTP(82)
4
4
4
4
Tune DWT
351.7 mb
829.1 mb
PARP(82)
2.0 GeV
1.9 GeV
1.9409 GeV
1.8 GeV
ATLAS
324.5 mb
768.0 mb
PARP(83)
0.5
0.5
0.5
0.5
PARP(84)
0.4
0.4
0.4
0.5
PARP(85)
0.9
1.0
1.0
0.33
PARP(86)
0.95
1.0
1.0
0.66
PARP(89)
1.8 TeV
1.8 TeV
1.96 TeV
1.0 TeV
0.25
0.25
0.16
0.16
PARP(62)
1.0
1.25
1.25
1.0
PARP(64)
1.0
0.2
0.2
1.0
PARP(67)
4.0
2.5
2.5
1.0
MSTP(91)
1
1
1
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!
ICHEP06
July 28, 2006
"Transverse" PTsum Density (GeV/c)
PARP(90)
"Transverse" PTsum Density: dPT/dhd
1.6
RDF Preliminary
PY Tune DW
generator level
1.2
PY Tune A
PY-ATLAS
0.8
1.96 TeV
0.4
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
500
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 Tune A, DW, ATLAS, and
HERWIG (without MPI).
Rick Field – Florida/CDF
Page 18
PYTHIA 6.2 Tunes
s(MPI) at 1.96 TeV
s(MPI) at 14 TeV
Tune A
309.7 mb
484.0 mb
PYTHIA 6.2 CTEQ5L
Parameter
Tune A
Tune DW
Tune DWT
ATLAS
MSTP(81)
1
1
1
1
Tune DW
351.7 mb
549.2 mb
MSTP(82)
4
4
4
4
Tune DWT
351.7 mb
829.1 mb
PARP(82)
2.0 GeV
1.9 GeV
1.9409 GeV
1.8 GeV
ATLAS
324.5 mb
768.0 mb
PARP(83)
0.5
0.5
0.5
0.5
PARP(84)
0.4
0.4
0.4
0.5
PARP(85)
0.9
1.0
1.0
0.33
"Transverse" Charged Particle Average pT
PARP(86)
0.95
1.0
1.0
0.66
PARP(89)
1.8 TeV
1.8 TeV
1.96 TeV
1.0 TeV
PARP(90)
0.25
0.25
0.16
0.16
PARP(62)
1.0
1.25
1.25
1.0
PARP(64)
1.0
0.2
0.2
1.0
PARP(67)
4.0
2.5
2.5
1.0
MSTP(91)
1
1
1
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!
ICHEP06
July 28, 2006
"Transverse" Charged PT (GeV/c)
1.5
RDF Preliminary
PY Tune A
PY Tune DW
generator level
1.3
1.1
PY-ATLAS
1.96 TeV
0.9
HERWIG
Leading Jet (|h|<2.0)
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.7
0
50
100
150
200
250
300
350
400
450
500
PT(particle jet#1) (GeV/c)
 Shows the “transverse” charged average pT,
versus PT(jet#1) for “leading jet” events at 1.96
TeV for Tune A, DW, ATLAS, and HERWIG
(without MPI).
Rick Field – Florida/CDF
Page 19
PYTHIA 6.2 Tunes
s(MPI) at 1.96 TeV
s(MPI) at 14 TeV
Tune A
309.7 mb
484.0 mb
351.7 mb
549.2 mb
351.7 mb
CDF
324.5
mbRun 2 Data!
829.1 mb
PYTHIA 6.2 CTEQ5L
Parameter
Tune A
Tune DW
Tune DWT
ATLAS
MSTP(81)
1
1
1
1
Tune DW
MSTP(82)
4
4
4
4
Tune DWT
PARP(82)
2.0 GeV
1.9 GeV
1.9409 GeV
1.8 GeV
ATLAS
PARP(83)
0.5
0.5
0.5
0.5
PARP(84)
0.4
0.4
PARP(85)
0.9
0.25
PARP(62)
1.0
PARP(64)
1.0
PARP(67)
4.0
MSTP(91)
1
PARP(91)
1.0
PARP(93)
5.0
1.96 TeV
1.1
0.9
0.25
0.16
0.16
1.25
1.25
1.0
0.2
0.2
1.0
2.5
2.5
1.0
1
1
1
PY-ATLAS
0.7
15.0
50
15.0
100
Identical to DW at 1.96 TeV but uses
ATLAS extrapolation to the LHC!
PY Tune A
PY Tune DW
generator level
1.1
PY-ATLAS
1.96 TeV
0.9
HERWIG
MidPoint R = 0.7 |h(jet#1) < 2
Leading Jet (|h|<2.0)
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.7
0
2.1 1.96 TeV2.1 HERWIG 1.0
0
ICHEP06
July 28, 2006
1.0 TeV
PY Tune A, DW
1.3
RDF Preliminary
"Leading
1.3 Jet"
data corrected to particle level
1.8 TeV 1.5 1.8 TeV
PARP(90)
0.33
"Transverse" Charged PT (GeV/c)
PARP(89)
1.0
CDF
1.0 Run 2 Preliminary
1.0
0.66
0.95
"Transverse" <PT> (GeV/c)
PARP(86)
"Transverse" Charged Particle Average pT
0.4
0.5Charged Average PT
"Transverse"
1.5
1.0
1.7
768.0 mb
50
100
150
200
250
300
350
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
PT(particle jet#1) (GeV/c)
400
450
500
5.0
150
250
Shows
charged average pT,
300the “transverse”
350
400
450
PT(jet#1) (GeV/c)
versus PT(jet#1) for “leading jet” events at 1.96
TeV for Tune A, DW, ATLAS, and HERWIG
(without MPI).
200
Rick Field – Florida/CDF
Page 20
PYTHIA 6.2 Tunes
s(MPI) at 1.96 TeV
s(MPI) at 14 TeV
Tune A
309.7 mb
484.0 mb
PYTHIA 6.2 CTEQ5L
Parameter
Tune A
Tune DW
Tune DWT
ATLAS
MSTP(81)
1
1
1
1
Tune DW
351.7 mb
549.2 mb
MSTP(82)
4
4
4
4
Tune DWT
351.7 mb
829.1 mb
PARP(82)
2.0 GeV
1.9 GeV
1.9409 GeV
1.8 GeV
ATLAS
324.5 mb
768.0 mb
PARP(83)
0.5
0.5
0.5
0.5
PARP(84)
0.4
0.4
0.4
0.5
"Transverse" Charged Particle Density: dN/dhd
PARP(85)
0.9
1.0
1.0
0.33
PARP(86)
0.95
1.0
1.0
0.66
PARP(89)
1.8 TeV
1.8 TeV
1.96 TeV
1.0 TeV
PARP(90)
0.25
0.25
0.16
0.16
PARP(62)
1.0
1.25
1.25
1.0
PARP(64)
1.0
0.2
0.2
1.0
PARP(67)
4.0
2.5
2.5
1.0
MSTP(91)
1
1
1
1
PARP(91)
1.0
2.1
2.1
1.0
PARP(93)
5.0
15.0
15.0
5.0
"Transverse" Charged Density
2.5
PY Tune DWT
generator level
2.0
1.5
PY Tune DW
1.0
14 TeV
0.5
HERWIG
ICHEP06
July 28, 2006
Leading Jet (|h|<2.0)
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
0.0
0
Identical to DW at 1.96 TeV but uses
ATLAS extrapolation to the LHC!
PY-ATLAS
RDF Preliminary
250
500
750
1000
1250
1500
1750
2000
PT(particle jet#1) (GeV/c)
 Shows the “transverse” charged particle density,
dN/dhd, versus PT(jet#1) for “leading jet”
events at 14 TeV for Tune A, DW, ATLAS, and
HERWIG (without MPI).
Rick Field – Florida/CDF
Page 21
PYTHIA 6.2 Tunes
s(MPI) at 1.96 TeV
s(MPI) at 14 TeV
Tune A
309.7 mb
484.0 mb
PYTHIA 6.2 CTEQ5L
Parameter
Tune A
Tune DW
Tune DWT
ATLAS
MSTP(81)
1
1
1
1
Tune DW
351.7 mb
549.2 mb
MSTP(82)
4
4
4
4
Tune DWT
351.7 mb
829.1 mb
PARP(82)
2.0 GeV
1.9 GeV
1.9409 GeV
1.8 GeV
ATLAS
324.5 mb
768.0 mb
PARP(83)
0.5
0.5
0.5
0.5
PARP(84)
0.4
0.4
0.4
0.5
PARP(85)
0.9
1.0
1.0
0.33
0.95
1.0
1.0
0.66
PARP(89)
1.8 TeV
1.8 TeV
1.96 TeV
1.0 TeV
PARP(90)
0.25
0.25
0.16
0.16
PARP(62)
1.0
1.25
1.25
1.0
PARP(64)
1.0
0.2
0.2
1.0
PARP(67)
4.0
2.5
2.5
1.0
MSTP(91)
1
1
1
1
PARP(91)
1.0
2.1
2.1
1.0
PARP(93)
5.0
15.0
15.0
5.0
"Transverse" PTsum Density (GeV/c)
PARP(86)
"Transverse" PTsum Density: dPT/dhd
8.0
generator level
6.0
PY Tune DW
4.0
PY-ATLAS
14 TeV
2.0
ICHEP06
July 28, 2006
Leading Jet (|h|<2.0)
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
HERWIG
0.0
0
Identical to DW at 1.96 TeV but uses
ATLAS extrapolation to the LHC!
PY Tune DWT
RDF Preliminary
250
500
750
1000
1250
1500
1750
2000
PT(particle jet#1) (GeV/c)
 Shows the “transverse” charged PTsum density,
dPT/dhd, versus PT(jet#1) for “leading jet”
events at 14 TeV for Tune A, DW, ATLAS, and
HERWIG (without MPI).
Rick Field – Florida/CDF
Page 22
PYTHIA 6.2 Tunes
s(MPI) at 1.96 TeV
s(MPI) at 14 TeV
Tune A
309.7 mb
484.0 mb
PYTHIA 6.2 CTEQ5L
Parameter
Tune A
Tune DW
Tune DWT
ATLAS
MSTP(81)
1
1
1
1
Tune DW
351.7 mb
549.2 mb
MSTP(82)
4
4
4
4
Tune DWT
351.7 mb
829.1 mb
PARP(82)
2.0 GeV
1.9 GeV
1.9409 GeV
1.8 GeV
ATLAS
324.5 mb
768.0 mb
PARP(83)
0.5
0.5
0.5
0.5
PARP(84)
0.4
0.4
0.4
0.5
PARP(85)
0.9
1.0
1.0
0.33
PARP(86)
0.95
1.0
1.0
0.66
PARP(89)
1.8 TeV
1.8 TeV
1.96 TeV
1.0 TeV
PARP(90)
0.25
0.25
0.16
0.16
PARP(62)
1.0
1.25
1.25
1.0
PARP(64)
1.0
0.2
0.2
1.0
"Transverse" Charged Particle Average pT
PARP(67)
4.0
2.5
2.5
1.0
MSTP(91)
1
1
1
1
PARP(91)
1.0
2.1
2.1
1.0
PARP(93)
5.0
15.0
15.0
5.0
"Transverse" Charged PT (GeV/c)
2.5
RDF Preliminary
PY Tune DW
2.0
HERWIG
1.5
14 TeV
PY-ATLAS
ICHEP06
July 28, 2006
Leading Jet (|h|<2.0)
Charged Particles (|h|<1.0, PT>0.5 GeV/c)
1.0
0
Identical to DW at 1.96 TeV but uses
ATLAS extrapolation to the LHC!
PY Tune DWT
generator level
250
500
750
1000
1250
1500
1750
2000
PT(particle jet#1) (GeV/c)
 Shows the “transverse” charged average pT,
versus PT(jet#1) for “leading jet” events at 14
TeV for Tune A, DW, ATLAS, and HERWIG
(without MPI).
Rick Field – Florida/CDF
Page 23
Summary
Tevatron
Outgoing Parton
LHC
PT(hard)
“Minumum Bias” Collisions
Initial-State Radiation
Proton
Proton
AntiProton
AntiProton
Underlying Event
Outgoing Parton
Underlying Event
Final-State
Radiation
 The ATLAS tune is “goofy”! It produces too many “soft” particles. The charged
particle <pT> is too low and does not agree with the CDF Run 2 data. The ATLAS tune
agrees with <Nchg> but not with <PTsum> at the Tevatron.
 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 
distribution).
 PYTHIA Tune DWT is identical to Tune DW at 1.96 TeV but uses the ATLAS energy
extrapolation to the LHC (i.e. PARP(90) = 0.16).
ICHEP06
July 28, 2006
Rick Field – Florida/CDF
Page 24
Summary
Tevatron
Outgoing Parton
LHC
PT(hard)
“Minumum Bias” Collisions
Initial-State Radiation
Proton
Proton
AntiProton
AntiProton
Underlying Event
Outgoing Parton


Underlying Event
Final-State
Radiation
The ATLAS tune cannot be right
because it does not fit the Tevatron
Right now
like Tune
The ATLAS tune is “goofy”!data.
It produces
too Imany
“soft”DW.
particles. The charged
Probably
no agree
tune will
theCDF
LHCRun
data.
particle <pT> is too low and
does not
withfitthe
2 data. The ATLAS tune
Thatwith
is why
MB&UE
agrees with <Nchg> but not
<PTwe
sumplan
> at to
themeasure
Tevatron.
at CMS and retune the Monte-Carlo
models!
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 
distribution).
 PYTHIA Tune DWT is identical to Tune DW at 1.96 TeV but uses the ATLAS energy
extrapolation to the LHC (i.e. PARP(90) = 0.16).
ICHEP06
July 28, 2006
Rick Field – Florida/CDF
Page 25