The “Underlying Event” CDF-LHC Comparisons
description
Transcript of The “Underlying Event” CDF-LHC Comparisons
LHC/CMS Journal Club November 30, 2005
Rick Field - Florida/CMS/CDF Page 1
The “Underlying Event”The “Underlying Event”CDF-LHC ComparisonsCDF-LHC Comparisons
Proton AntiProton
Drell-Yan Production Lepton
Underlying Event Underlying Event
Initial-State Radiation
Anti-Lepton
Outline of Talk
PT(Z-boson): Tuning to fit the PT(Z) distribution in Run 2 at CDF.
Jet Production: The “underlying event” in high pT jet production in Run 2 at CDF.
Extrapolations to the LHC: The “underlying event” in high pT jet production and Drell-Yan at CMS.
Drell-Yan: The “underlying event” in Drell-Yan production in Run 2 at CDF.
Great process to study the “underlying event”!
Proton AntiProton
High PT Jet Production
PT(hard)
Outgoing Parton
Outgoing Parton
Underlying Event Underlying Event
Final-State Radiation
Initial-State Radiation
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Jet #1 Direction
“Transverse” “Transverse”
“Toward”
“Away”
“Toward-Side” Jet
“Away-Side” Jet
The “Transverse” RegionThe “Transverse” Regionas defined by the Leading Jetas defined by the Leading Jet
Look at the “transverse” region as defined by the leading calorimeter jet (MidPoint, R = 0.7, fmerge = 0.75, || < 2).
Define || < 60o as “Toward”, 60o < - < 120o and 60o < < 120o as “Transverse 1” and “Transverse 2”, and || > 120o as “Away”. Each of the two “transverse” regions have area = 2x60o = 4/6. The overall “transverse” region is the sum of the two transverse regions ( = 2x120o = 4/3).
Study the charged particles (pT > 0.5 GeV/c, || < 1) and form the charged particle density, dNchg/dhdf, and the charged scalar pT sum density, dPTsum/dd, by dividing by the area in - space.
Study the calorimeter towers (ET > 0.1 GeV, || < 1) and form the scalar ET sum density, dETsum/dd.
Charged Particles (pT > 0.5 GeV/c, || < 1)Calorimeter Towers (ET > 0.1 GeV, || < 1)
“Transverse” region is very sensitive to the “underlying event”!
Calorimeter Jet #1 Direction
“Toward”
“Transverse” “Transverse”
“Away”
-1 +1
2
0
Leading Jet
Toward Region
Transverse Region
Transverse Region
Away Region
Away Region
Look at the charged particle density and the
ETsum density in the “transverse” region!
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The “Transverse” RegionThe “Transverse” Regionas defined by the Leading Jetas defined by the Leading Jet
Look at the “transverse” region as defined by the leading calorimeter jet (MidPoint, R = 0.7, fmerge = 0.75, || < 2).
Define || < 60o as “Toward”, 60o < - < 120o and 60o < < 120o as “Transverse 1” and “Transverse 2”, and || > 120o as “Away”. Each of the two “transverse” regions have area = 2x60o = 4/6. The overall “transverse” region is the sum of the two transverse regions ( = 2x120o = 4/3).
Study the charged particles (pT > 0.5 GeV/c, || < 1) and form the charged particle density, dNchg/dd, and the charged scalar pT sum density, dPTsum/dd, by dividing by the area in - space.
Study the calorimeter towers (ET > 0.1 GeV, || < 1) and form the scalar ET sum density, dETsum/dd.
Charged Particles (pT > 0.5 GeV/c, || < 1)Calorimeter Towers (ET > 0.1 GeV, || < 1)
Calorimeter Jet #1 Direction
“Toward”
“Transverse” “Transverse”
“Away”
-1 +1
2
0
Leading Jet
Toward Region
Transverse Region
Transverse Region
Away Region
Away Region
Look at the charged particle density and the
ETsum density in the “transverse” region!
Jet #1 Direction
“Transverse” “Transverse”
“Toward”
“Away”
“Toward-Side” Jet
“Away-Side” Jet
Jet #3
“Transverse” region recieves contributions from initial & final-
state radiation!
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The “Underlying Event” inThe “Underlying Event” inHigh PHigh PTT Jet Production (CDF) Jet Production (CDF)
The “Underlying Event” in High PT Jet Production
“Transverse” <Densities> vs PT(jet#1)
Jet #1 Direction
“Toward”
“Transverse” “Transverse”
“Away”
"Transverse" Charged Particle Density: dN/dd
0.0
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1.0
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PT(jet#1) (GeV/c)
"Tra
ns
vers
e" C
har
ge
d D
ensi
ty
CDF Run 2 Preliminarydata corrected to particle level
MidPoint R = 0.7 |(jet#1) < 2
Charged Particles (||<1.0, PT>0.5 GeV/c) 1.96 TeV
PY Tune A
HW
"Leading Jet"
"Transverse" Charged PTsum Density: dPT/dd
0.0
0.4
0.8
1.2
1.6
2.0
0 50 100 150 200 250 300 350 400 450
PT(jet#1) (GeV/c)
"Tra
ns
vers
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Tsu
m D
ens
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(G
eV
/c) CDF Run 2 Preliminary
data corrected to particle level
MidPoint R = 0.7 |(jet#1) < 2
Charged Particles (||<1.0, PT>0.5 GeV/c)
1.96 TeV
"Leading Jet"
PY Tune A
HW
HERWIG (without MPI) lies below the data for PT(jet#1) < 200 GeV/c!
Proton AntiProton
High PT Jet Production
PT(hard)
Outgoing Parton
Outgoing Parton
Underlying Event Underlying Event
Final-State Radiation
Initial-State Radiation
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The “Central” RegionThe “Central” Regionin Drell-Yan Productionin Drell-Yan Production
Look at the “central” region after removing the lepton-pair.
Study the charged particles (pT > 0.5 GeV/c, || < 1) and form the charged particle density, dNchg/dd, and the charged scalar pT sum density, dPTsum/dd, by dividing by the area in - space.
Study the calorimeter towers (ET > 0.1 GeV, || < 1) and form the scalar ET sum density, dETsum/dd.
Proton AntiProton
Drell-Yan Production Lepton
Underlying Event Underlying Event
Initial-State Radiation
Anti-Lepton
Charged Particles (pT > 0.5 GeV/c, || < 1)Calorimeter Towers (ET > 0.1 GeV, || < 1)
After removing the lepton-pair everything else is the
“underlying event”!
Proton AntiProton
Multiple Parton Interactions
Anti-Lepton
Lepton
Underlying Event Underlying Event
-1 +1
2
0
Central Region
Look at the charged particle density and the
ETsum density in the “central” region!
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CDF Run 1 PCDF Run 1 PTT(Z)(Z)
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).
Z-Boson Transverse Momentum
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0.04
0.08
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0 2 4 6 8 10 12 14 16 18 20
Z-Boson PT (GeV/c)
PT
Dis
trib
uti
on
1/N
dN
/dP
T
CDF Run 1 Data
PYTHIA Tune A
PYTHIA Tune A25
PYTHIA Tune A50
CDF Run 1published
1.8 TeV
Normalized to 1
s = 1.0
s = 2.5
s = 5.0
Parameter Tune ATune 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
PARP(89) 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
UE Parameters
ISR Parameter
Intrensic KT
PYTHIA 6.2 CTEQ5L
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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 The Q2 = kT2 in s for space-like showers is scaled by PARP(64)!
Effective Q cut-off, below which space-like showers are not evolved.
CDF Run 1 PCDF Run 1 PTT(Z)(Z)
Shows the Run 1 Z-boson pT distribution (<pT(Z)> ≈ 11.5 GeV/c) compared with PYTHIA Tune AW (<pT(Z)> = 11.7 GeV/c).
UE Parameters
ISR Parameters
Intrensic KT
Z-Boson Transverse Momentum
0.00
0.04
0.08
0.12
0 2 4 6 8 10 12 14 16 18 20
Z-Boson PT (GeV/c)
PT
Dis
trib
uti
on
1/N
dN
/dP
T
CDF Run 1 Data
PYTHIA Tune AWCDF Run 1
published
1.8 TeV
Normalized to 1
s = 2.1
PYTHIA 6.2 CTEQ5L
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Drell-Yan ProductionDrell-Yan Productionat CDFat CDF
Shows the lepton-pair average PT versus the lepton-pair invariant mass at 1.96 TeV for PYTHIA Tune AW and PYTHIA Tune A.
Lepton-Pair Transverse Momentum
0
5
10
15
20
0 50 100 150 200 250
Lepton-Pair Invariant Mass (GeV)
Av
era
ge
Pai
r P
T
Drell-Yan1.96 TeV
RDF Preliminarygenerator level
PY Tune A
PY Tune AW
Shows the lepton-pair average PT versus the lepton-pair invariant mass at 1.96 TeV for PYTHIA Tune AW and HERWIG.
<PT(pair)> versus M(pair)Lepton-Pair Transverse Momentum
Proton AntiProton
Drell-Yan Production
PT(pair)
Lepton-Pair
Outgoing Parton
Underlying Event Underlying Event
Initial-State Radiation
Final-State Radiation
Lepton-Pair Transverse Momentum
0
5
10
15
20
0 50 100 150 200 250
Lepton-Pair Invariant Mass (GeV)
Av
era
ge
Pai
r P
T
Drell-Yan1.96 TeV
RDF Preliminarygenerator level
PY Tune AW
HERWIG
Z Z
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Drell-Yan ProductionDrell-Yan Productionat CMSat CMS
Shows the lepton-pair average PT versus the lepton-pair invariant mass at 1.96 TeV for PYTHIA Tune AW and HERWIG.
Shows the lepton-pair average PT versus the lepton-pair invariant mass at 14 TeV for PYTHIA Tune AW and HERWIG.
<PT(pair)> versus M(pair)Lepton-Pair Transverse Momentum
Proton AntiProton
Drell-Yan Production
PT(pair)
Lepton-Pair
Outgoing Parton
Underlying Event Underlying Event
Initial-State Radiation
Final-State Radiation
Lepton-Pair Transverse Momentum
0
5
10
15
20
0 50 100 150 200 250
Lepton-Pair Invariant Mass (GeV)
Av
era
ge
Pai
r P
T
Drell-Yan1.96 TeV
RDF Preliminarygenerator level
PY Tune AW
HERWIG
Lepton-Pair Transverse Momentum
0
10
20
30
40
0 50 100 150 200 250
Lepton-Pair Invariant Mass (GeV)
Av
era
ge
Pai
r P
T
Drell-Yan
RDF Preliminarygenerator level
PY Tune AW
HERWIGCDF
LHC
The lepton-pair <PT> much larger at the LHC!
Z Z
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Rick Field - Florida/CMS/CDF Page 10
The “Underlying Event” inThe “Underlying Event” inDrell-Yan Production (CDF)Drell-Yan Production (CDF)
Shows the charged particle density versus the lepton-pair invariant mass at 1.96 TeV for PYTHIA Tune AW and PYTHIA Tune A.
Shows the charged particle density versus the lepton-pair invariant mass at 1.96 TeV for PYTHIA Tune AW and HERWIG (with no MPI).
Charged particle density versus M(pair)
Charged Particle Density: dN/dd
0.0
0.2
0.4
0.6
0.8
1.0
0 50 100 150 200 250
Lepton-Pair Invariant Mass (GeV)
Ch
arg
ed
Pa
rtic
le D
en
sity
RDF Preliminarygenerator level
Drell-Yan1.96 TeV
Charged Particles (||<1.0, PT>0.5 GeV/c)
PY Tune A
PY Tune AW
The “Underlying Event”
Proton AntiProton
Drell-Yan Production Lepton
Underlying Event Underlying Event
Initial-State Radiation
Anti-Lepton
Charged Particle Density: dN/dd
0.0
0.2
0.4
0.6
0.8
1.0
0 50 100 150 200 250
Lepton-Pair Invariant Mass (GeV)
Ch
arg
ed P
arti
cle
De
nsi
ty
RDF Preliminarygenerator level
Drell-Yan1.96 TeV
PY Tune AW
HERWIG
Charged Particles (||<1.0, PT>0.5 GeV/c)(excluding lepton-pair )
HERWIG (without MPI) is much less active than
PY Tune AW (with MPI)!
Z Z
LHC/CMS Journal Club November 30, 2005
Rick Field - Florida/CMS/CDF Page 11
The “Underlying Event” inThe “Underlying Event” inDrell-Yan Production (CMS)Drell-Yan Production (CMS)
Charged particle density versus the lepton-pair invariant mass at 1.96 TeV for PYTHIA Tune AW and HERWIG (without MPI).
Charged particle density versus the lepton-pair invariant mass at 14 TeV for PYTHIA Tune AW and HERWIG (without MPI).
The “Underlying Event”
Proton AntiProton
Drell-Yan Production Lepton
Underlying Event Underlying Event
Initial-State Radiation
Anti-Lepton
Charged Particle Density: dN/dd
0.0
0.2
0.4
0.6
0.8
1.0
0 50 100 150 200 250
Lepton-Pair Invariant Mass (GeV)
Ch
arg
ed P
arti
cle
De
nsi
ty
RDF Preliminarygenerator level
Drell-Yan1.96 TeV
PY Tune AW
HERWIG
Charged Particles (||<1.0, PT>0.5 GeV/c)(excluding lepton-pair )
Charged Particle Density: dN/dd
0.0
0.5
1.0
1.5
0 50 100 150 200 250
Lepton-Pair Invariant Mass (GeV)
Ch
arg
ed P
arti
cle
De
nsi
ty
RDF Preliminarygenerator level
Drell-YanCharged Particles (||<1.0, PT>0.5 GeV/c)
(excluding lepton-pair )
PY Tune AW
HERWIG
LHC
CDF
Charged particle density versus M(pair)
“Underlying event” much more active at the LHC!
HERWIG (without MPI) is much less active than
PY Tune AW (with MPI)!
Z
LHC/CMS Journal Club November 30, 2005
Rick Field - Florida/CMS/CDF Page 12
The “Underlying Event” inThe “Underlying Event” inDrell-Yan Production (CDF)Drell-Yan Production (CDF)
Shows the charged PTsum density versus the lepton-pair invariant mass at 1.96 TeV for PYTHIA Tune AW and PYTHIA Tune A.
Shows the charged PTsum density versus the lepton-pair invariant mass at 1.96 TeV for PYTHIA Tune AW and HERWIG (without MPI).
Charged PTsum density versus M(pair)
Charged PTsum Density: dPT/dd
0.0
0.4
0.8
1.2
1.6
0 50 100 150 200 250
Lepton-Pair Invariant Mass (GeV)
Ch
arg
ed
PT
sum
De
nsi
ty (
GeV
/c) RDF Preliminary
generator level
Drell-Yan1.96 TeV Charged Particles (||<1.0, PT>0.5 GeV/c)
PY Tune A
PY Tune AW
The “Underlying Event”
Charged PTsum Density: dPT/dd
0.0
0.4
0.8
1.2
1.6
0 50 100 150 200 250
Lepton-Pair Invariant Mass (GeV)
Ch
arg
ed P
Tsu
m D
ensi
ty (
GeV
/c) RDF Preliminary
generator level
Drell-Yan1.96 TeV
PY Tune AW
HERWIGCharged Particles (||<1.0, PT>0.5 GeV/c)
(excluding lepton-pair )
Proton AntiProton
Drell-Yan Production Lepton
Underlying Event Underlying Event
Initial-State Radiation
Anti-Lepton
HERWIG (without MPI) is much less active than
PY Tune AW (with MPI)!
Z
LHC/CMS Journal Club November 30, 2005
Rick Field - Florida/CMS/CDF Page 13
The “Underlying Event” inThe “Underlying Event” inDrell-Yan Production (CMS)Drell-Yan Production (CMS)
Charged PTsum density versus the lepton-pair invariant mass at 1.96 TeV for PYTHIA Tune AW and HERWIG (without MPI).
Charged PTsum density versus the lepton-pair invariant mass at 14 TeV for PYTHIA Tune AW and HERWIG (without MPI).
The “Underlying Event”
Proton AntiProton
Drell-Yan Production Lepton
Underlying Event Underlying Event
Initial-State Radiation
Anti-Lepton
Charged PTsum Density: dPT/dd
0.0
0.4
0.8
1.2
1.6
0 50 100 150 200 250
Lepton-Pair Invariant Mass (GeV)
Ch
arg
ed P
Tsu
m D
en
sity
(G
eV/c
) RDF Preliminarygenerator level
Drell-Yan1.96 TeV
PY Tune AW
HERWIGCharged Particles (||<1.0, PT>0.5 GeV/c)
(excluding lepton-pair )
Charged PTsum Density: dPT/dd
0.0
0.5
1.0
1.5
2.0
2.5
0 50 100 150 200 250
Lepton-Pair Invariant Mass (GeV)
Ch
arg
ed P
Tsu
m D
en
sity
(G
eV/c
) RDF Preliminarygenerator level
Drell-Yan
PY Tune AW
HERWIG
LHC
CDF
Charged Particles (||<1.0, PT>0.5 GeV/c)(excluding lepton-pair )
Charged PTsum density versus M(pair)
“Underlying event” much more active at the LHC!
HERWIG (without MPI) is much less active than
PY Tune AW (with MPI)!
Z
LHC/CMS Journal Club November 30, 2005
Rick Field - Florida/CMS/CDF Page 14
The “Underlying Event” inThe “Underlying Event” inDrell-Yan Production (CMS)Drell-Yan Production (CMS)
ETsum density versus the lepton-pair invariant mass at 1.96 TeV for PYTHIA Tune AW and HERWIG (without MPI).
ETsum density versus the lepton-pair invariant mass at 14 TeV for PYTHIA Tune AW and HERWIG (without MPI).
ETsum density versus M(pair)The “Underlying Event”
Proton AntiProton
Drell-Yan Production Lepton
Underlying Event Underlying Event
Initial-State Radiation
Anti-Lepton
Transverse Energy Density: dET/dd
0.0
0.5
1.0
1.5
2.0
0 50 100 150 200 250
Lepton-Pair Invariant Mass (GeV)
ET
sum
Den
sity
(G
eV)
RDF Preliminarygenerator level
All Particles (||<1.0, all PT)(excluding lepton-pair )
Drell-Yan1.96 TeV
PY Tune AW
HERWIG
Transverse Energy Density: dET/dd
0.0
1.0
2.0
3.0
4.0
5.0
0 50 100 150 200 250
Lepton-Pair Invariant Mass (GeV)
ET
sum
Den
sity
(G
eV)
RDF Preliminarygenerator level
Drell-Yan
PY Tune AW
HERWIG
All Particles (||<1.0, all PT)(excluding lepton-pair )
LHC
CDF
ZZ
LHC/CMS Journal Club November 30, 2005
Rick Field - Florida/CMS/CDF Page 15
The “Underlying Event”The “Underlying Event”Drell-Yan vs Jets at CDFDrell-Yan vs Jets at CDF
-1 +1
2
0
Central Region
The “Underlying Event” in High PT Lepton-Pair and Jet Production
Jet #1 Direction
“Toward”
“Transverse” “Transverse”
“Away”
Charged Particle Density: dN/dd
0.0
0.2
0.4
0.6
0.8
1.0
0 50 100 150 200 250 300 350 400 450 500
PT(jet#1) or Lepton-Pair Mass
Ch
arg
ed P
arti
cle
Den
sity
RDF Preliminarygenerator level
1.96 TeV
PY Tune AW
HERWIG
Charged Particles (||<1.0, PT>0.5 GeV/c)(excluding lepton-pair )
"Leading Jet"
Drell-Yan
Charged PTsum Density: dPT/dd
0.0
0.4
0.8
1.2
1.6
0 50 100 150 200 250 300 350 400 450 500
PT(jet#1) or Lepton-Pair Mass
Ch
arg
ed P
Tsu
m D
ensi
ty (
GeV
/c)
"Leading Jet"RDF Preliminarygenerator level
1.96 TeVPY Tune AW
HERWIGCharged Particles (||<1.0, PT>0.5 GeV/c)
(excluding lepton-pair )
Drell-Yan
Lepton
Anti-Lepton
“Central Region”
-1 +1
2
0
Leading Jet
Toward Region
Transverse Region
Transverse Region
Away Region
Away Region
Drell-Yan “Leading Jet”
LHC/CMS Journal Club November 30, 2005
Rick Field - Florida/CMS/CDF Page 16
The “Underlying Event” inThe “Underlying Event” inHigh PHigh PTT Jet Production (CMS) Jet Production (CMS)
Charged particle density in the “Transverse” region versus PT(jet#1) at 1.96 TeV for PY Tune AW and HERWIG (without MPI).
Charged particle density in the “Transverse” region versus PT(jet#1) at 14 TeV for PY Tune AW and HERWIG (without MPI).
The “Underlying Event”
"Transverse" Charged Particle Density: dN/dd
0.0
0.2
0.4
0.6
0.8
1.0
0 50 100 150 200 250 300 350 400 450 500
PT(particle jet#1) (GeV/c)
"Tra
ns
vers
e" C
ha
rge
d D
en
sity
RDF Preliminarygenerator level
Charged Particles (||<1.0, PT>0.5 GeV/c) "Leading Jet"
PY Tune AW
1.96 TeV
HERWIG
"Transverse" Charged Particle Density: dN/dd
0.0
0.5
1.0
1.5
2.0
0 250 500 750 1000 1250 1500 1750 2000 2250 2500
PT(particle jet#1) (GeV/c)
"Tra
ns
vers
e" C
ha
rge
d D
en
sity
RDF Preliminarygenerator level
Charged Particles (||<1.0, PT>0.5 GeV/c) "Leading Jet"
PY Tune AW
CDF
LHC
HERWIG
Charged particle density versus PT(jet#1)
“Underlying event” much more active at the LHC!
Proton AntiProton
High PT Jet Production
PT(hard)
Outgoing Parton
Outgoing Parton
Underlying Event Underlying Event
Final-State Radiation
Initial-State Radiation
LHC/CMS Journal Club November 30, 2005
Rick Field - Florida/CMS/CDF Page 17
The “Underlying Event” inThe “Underlying Event” inHigh PHigh PTT Jet Production (CMS) Jet Production (CMS)
Charged PTsum density in the “Transverse” region versus PT(jet#1) at 1.96 TeV for PY Tune AW and HERWIG (without MPI).
Charged PTsum density in the “Transverse” region versus PT(jet#1) at 14 TeV for PY Tune AW and HERWIG (without MPI)..
The “Underlying Event”
"Transverse" PTsum Density: dPT/dd
0.0
0.5
1.0
1.5
2.0
0 50 100 150 200 250 300 350 400 450 500
PT(particle jet#1) (GeV/c)
"Tra
ns
vers
e" P
Ts
um
Den
sit
y (
Ge
V/c
)
Charged Particles (||<1.0, PT>0.5 GeV/c)
RDF Preliminarygenerator level
"Leading Jet"
PY Tune AW
HERWIG
1.96 TeV
"Transverse" PTsum Density: dPT/dd
0.0
2.0
4.0
6.0
8.0
0 250 500 750 1000 1250 1500 1750 2000 2250 2500
PT(particle jet#1) (GeV/c)
"Tra
ns
vers
e" P
Ts
um
Den
sit
y (
Ge
V/c
)
Charged Particles (||<1.0, PT>0.5 GeV/c)
RDF Preliminarygenerator level
"Leading Jet"
PY Tune AW
HERWIG
CDF
LHC
Charged PTsum density versus PT(jet#1)
“Underlying event” much more active at the LHC!
Proton AntiProton
High PT Jet Production
PT(hard)
Outgoing Parton
Outgoing Parton
Underlying Event Underlying Event
Final-State Radiation
Initial-State Radiation
LHC/CMS Journal Club November 30, 2005
Rick Field - Florida/CMS/CDF Page 18
The “Underlying Event” inThe “Underlying Event” inHigh PHigh PTT Jet Production (CMS) Jet Production (CMS)
ETsum density in the “Transverse” region versus PT(jet#1) at 1.96 TeV for PY Tune AW and HERWIG (without MPI).
ETsum density in the “Transverse” region versus PT(jet#1) at 14 TeV for PY Tune AW and HERWIG (without MPI).
The “Underlying Event”
"Transverse" ETsum Density: dET/dd
0.0
1.0
2.0
3.0
4.0
0 50 100 150 200 250 300 350 400 450 500
PT(particle jet#1) (GeV/c)
"Tra
ns
ve
rse
" E
Ts
um
De
ns
ity
(G
eV
)
All Particles (||<1.0, all PT)
RDF Preliminarygenerator level
"Leading Jet"
PY Tune AW
HERWIG
1.96 TeV
"Transverse" ETsum Density: dET/dd
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
0 250 500 750 1000 1250 1500 1750 2000 2250 2500
PT(particle jet#1) (GeV/c)
"Tra
ns
vers
e" E
Ts
um
Den
sit
y (
Ge
V)
All Particles (||<1.0, all PT)
RDF Preliminarygenerator level
"Leading Jet"
PY Tune AW
HERWIG
LHC
CDF
ETsum density versus PT(jet#1)
“Underlying event” much more active at the LHC!
Proton AntiProton
High PT Jet Production
PT(hard)
Outgoing Parton
Outgoing Parton
Underlying Event Underlying Event
Final-State Radiation
Initial-State Radiation
LHC/CMS Journal Club November 30, 2005
Rick Field - Florida/CMS/CDF Page 19
The “Underlying Event”The “Underlying Event”Drell-Yan vs Jets at CMSDrell-Yan vs Jets at CMS
-1 +1
2
0
Central Region
The “Underlying Event” in High PT Lepton-Pair and Jet Production
Jet #1 Direction
“Toward”
“Transverse” “Transverse”
“Away”
Lepton
Anti-Lepton
“Central Region”
-1 +1
2
0
Leading Jet
Toward Region
Transverse Region
Transverse Region
Away Region
Away Region
Drell-Yan “Leading Jet”
Charged Particle Density: dN/dd
0.0
0.5
1.0
1.5
2.0
0 250 500 750 1000 1250 1500 1750 2000 2250 2500
PT(jet#1) orLepton-Pair Mass
Ch
arg
ed P
arti
cle
Den
sity
"Leading Jet"
PY Tune AW
HERWIG
RDF Preliminarygenerator level
Drell-YanCharged Particles (||<1.0, PT>0.5 GeV/c)
(excluding lepton-pair )
14 TeV
Charged PTsum Density: dPT/dd
0.0
2.0
4.0
6.0
8.0
0 250 500 750 1000 1250 1500 1750 2000 2250 2500
PT(jet#1) or Lepton-Pair Mass
Ch
arg
ed P
Tsu
m D
en
sity
(G
eV/c
) RDF Preliminarygenerator level
"Leading Jet"PY Tune AW
HERWIG
Drell-Yan
14 TeV
Charged Particles (||<1.0, PT>0.5 GeV/c)(excluding lepton-pair )
LHC/CMS Journal Club November 30, 2005
Rick Field - Florida/CMS/CDF Page 20
Proton Proton
High PT Jet Production
PT(hard)
Outgoing Parton
Outgoing Parton
Underlying Event Underlying Event
Final-State Radiation
Initial-State Radiation
UE&MB@CMSUE&MB@CMS
“Underlying Event” Studies: The “transverse region” in “leading Jet” and “back-to-back” jet production. The “central region” in Drell-Yan production. (requires charged tracks and calorimeter and muons for Drell-Yan)
Drell-Yan Studies: Transverse momentum distribution of the lepton-pair versus the mass of the lepton-pair, <pT(pair)>, <pT
2(pair)>, ds/dpT(pair) (only requires muons). Event structure for large lepton-pair pT (i.e. +jets, requires muons and calorimeter).
Min-Bias Studies: Charged particle distributions and correlations. Construct “charged particle jets” and look at “mini-jet” structure and the onset of the “underlying event”. (requires only charged tracks)
Proton Proton
Drell-Yan Production Lepton
Underlying Event Underlying Event
Initial-State Radiation
Anti-Lepton
Proton Proton
“Minimum-Bias” Collisions
Proton Proton
Drell-Yan Production
PT(pair)
Lepton-Pair
Outgoing Parton
Underlying Event Underlying Event
Initial-State Radiation
Final-State Radiation
LHC/CMS Journal Club November 30, 2005
Rick Field - Florida/CMS/CDF Page 21
Proton Proton
High PT Jet Production
PT(hard)
Outgoing Parton
Outgoing Parton
Underlying Event Underlying Event
Final-State Radiation
Initial-State Radiation
UE&MB@CMSUE&MB@CMS
“Underlying Event” Studies: The “transverse region” in “leading Jet” and “back-to-back” jet production. The “central region” in Drell-Yan production. (requires charged tracks and calorimeter and muons for Drell-Yan)
Drell-Yan Studies: Transverse momentum distribution of the lepton-pair versus the mass of the lepton-pair, <pT(pair)>, <pT
2(pair)>, ds/dpT(pair) (only requires muons). Event structure for large lepton-pair pT (i.e. +jets, requires muons and calorimeter).
Min-Bias Studies: Charged particle distributions and correlations. Construct “charged particle jets” and look at “mini-jet” structure and the onset of the “underlying event”. (requires only charged tracks)
Proton Proton
Drell-Yan Production Lepton
Underlying Event Underlying Event
Initial-State Radiation
Anti-Lepton
Proton Proton
“Minimum-Bias” Collisions
Proton Proton
Drell-Yan Production
PT(pair)
Lepton-Pair
Outgoing Parton
Underlying Event Underlying Event
Initial-State Radiation
Final-State Radiation
UE&MB@CMSRick Field (Florida)
Darin Acosta (Florida)Albert De Roeck (CERN)
Paolo Bartalini (UF Postdoc at CERN)Livio Fano' (INFN/Perugia at CERN)
Filippo Ambroglini (INFN/Perugia at CERN)