The “Underlying Event”
CDF-LHC Comparisons
High PT Jet Production
Outline of Talk
Outgoing Parton
PT(hard)
Initial-State
Radiation
Proton
AntiProton
Underlying Event
Outgoing Parton
Underlying Event
¨ Jet Production: The “underlying event” in high
pT jet production in Run 2 at CDF.
Final-State
Radiation
Drell-Yan Production
¨ PT(Z-boson): Tuning to fit the PT(Z)
distribution in Run 2 at CDF.
Lepton
Proton
AntiProton
Underlying Event
Underlying Event
Initial-State
Radiation
Anti-Lepton
Great process to study the
“underlying event”!
¨ Drell-Yan: The “underlying event” in
Drell-Yan production in Run 2 at CDF.
¨ Extrapolations to the LHC: The “underlying
event” in high pT jet production and DrellYan at CMS.
LHC/CMS Journal Club
November 30, 2005
Rick Field - Florida/CMS/CDF
Page 1
The “Transverse” Region
“Transverse” region is
very sensitive to the
“underlying event”!
as defined by the Leading Jet
Jet #1 Direction
Charged Particles (pT > 0.5 GeV/c, |η| < 1)
Calorimeter Towers (ET > 0.1 GeV, |η| < 1)
“Toward-Side” Jet
∆φ
Look at the charged
particle density and the
ETsum density in the
“transverse” region!
2π
Away Region
Calorimeter Jet #1
Direction
∆φ
Transverse
Region
“Toward”
“Toward”
“Transverse”
φ
Leading
Jet
“Transverse”
“Transverse”
Toward Region
“Transverse”
Transverse
Region
“Away”
“Away”
Away Region
“Away-Side” Jet
0
-1
η
+1
¨ Look at the “transverse” region as defined by the leading calorimeter jet (MidPoint, R = 0.7, fmerge = 0.75,
¨
¨
¨
|η| < 2).
o
o
o
o
o
Define |∆φ| < 60 as “Toward”, 60 < -∆φ < 120 and 60 < ∆φ < 120 as “Transverse 1” and “Transverse 2”,
o
o
and |∆φ| > 120 as “Away”. Each of the two “transverse” regions have area ∆η∆φ = 2x60 = 4π/6. The
o
overall “transverse” region is the sum of the two transverse regions (∆η∆φ = 2x120 = 4π/3).
Study the charged particles (pT > 0.5 GeV/c, |η| < 1) and form the charged particle density, dNchg/dhdf,
and the charged scalar pT sum density, dPTsum/dηdφ, by dividing by the area in η-φ space.
Study the calorimeter towers (ET > 0.1 GeV, |η| < 1) and form the scalar ET sum density, dETsum/dηdφ.
LHC/CMS Journal Club
November 30, 2005
Rick Field - Florida/CMS/CDF
Page 2
The “Transverse” Region
“Transverse” region
recieves contributions
from initial & finalstate radiation!
as defined by the Leading Jet
Jet #1 Direction
Charged Particles (pT > 0.5 GeV/c, |η| < 1)
Calorimeter Towers (ET > 0.1 GeV, |η| < 1)
“Toward-Side” Jet
∆φ
Look at the charged
particle density and the
ETsum density in the
“transverse” region!
2π
Away Region
Calorimeter Jet #1
Direction
∆φ
Transverse
Region
“Toward”
“Toward”
“Transverse”
“Transverse”
Jet #3
“Transverse”
φ
Leading
Jet
Toward Region
“Transverse”
Transverse
Region
“Away”
“Away”
Away Region
“Away-Side” Jet
0
-1
η
+1
¨ Look at the “transverse” region as defined by the leading calorimeter jet (MidPoint, R = 0.7, fmerge = 0.75,
¨
¨
¨
|η| < 2).
o
o
o
o
o
Define |∆φ| < 60 as “Toward”, 60 < -∆φ < 120 and 60 < ∆φ < 120 as “Transverse 1” and “Transverse 2”,
o
o
and |∆φ| > 120 as “Away”. Each of the two “transverse” regions have area ∆η∆φ = 2x60 = 4π/6. The
o
overall “transverse” region is the sum of the two transverse regions (∆η∆φ = 2x120 = 4π/3).
Study the charged particles (pT > 0.5 GeV/c, |η| < 1) and form the charged particle density, dNchg/dηdφ,
and the charged scalar pT sum density, dPTsum/dηdφ, by dividing by the area in η-φ space.
Study the calorimeter towers (ET > 0.1 GeV, |η| < 1) and form the scalar ET sum density, dETsum/dηdφ.
LHC/CMS Journal Club
November 30, 2005
Rick Field - Florida/CMS/CDF
Page 3
The “Underlying Event” in
High PT Jet Production (CDF)
Jet #1 Direction
∆φ
“Toward”
“Transverse”
HERWIG (without MPI)
lies below the data for
PT(jet#1) < 200 GeV/c!
“Away”
High PT Jet Production
Proton
Outgoing Parton
PY Tune A
HW
0.4
MidPoint R = 0.7 |η(jet#1) < 2
0.2
1.96 TeV
Charged Particles (|η|<1.0, PT>0.5 GeV/c)
0.0
0
50
100
150
200
250
300
350
400
450
PT(jet#1) (GeV/c)
"Transverse" Charged PTsum Density: dPT/dηdφ
Underlying Event
Final-State
Radiation
“Transverse” <Densities> vs PT(jet#1)
LHC/CMS Journal Club
November 30, 2005
0.6
2.0
AntiProton
Underlying Event
"Leading Jet"
data corrected to particle level
Outgoing Parton
PT(hard)
Initial-State
Radiation
CDF Run 2 Preliminary
0.8
"Transverse" PTsum Density (GeV/c)
“Transverse”
"Transverse" Charged Particle Density: dN/dηdφ
1.0
"Transverse" Charged Density
The “Underlying Event” in High
PT Jet Production
CDF Run 2 Preliminary
data corrected to particle level
1.6
"Leading Jet"
1.96 TeV
1.2
PY Tune A
0.8
MidPoint R = 0.7 |η(jet#1) < 2
HW
0.4
Charged Particles (|η|<1.0, PT>0.5 GeV/c)
0.0
0
50
100
Rick Field - Florida/CMS/CDF
150
200
250
300
350
400
450
PT(jet#1) (GeV/c)
Page 4
The “Central” Region
in Drell-Yan Production
Drell-Yan Production
Lepton
Look at the charged
particle density and the
ETsum density in the
“central” region!
Charged Particles (pT > 0.5 GeV/c, |η| < 1)
Calorimeter Towers (ET > 0.1 GeV, |η| < 1)
2π
Proton
AntiProton
Underlying Event
Underlying Event
Initial-State
Radiation
φ
Central Region
Anti-Lepton
Multiple Parton Interactions
Proton
Lepton
AntiProton
Underlying Event
0
Underlying Event
Anti-Lepton
-1
η
+1
After removing the leptonpair everything else is the
“underlying event”!
¨ Look at the “central” region after removing the lepton-pair.
¨ Study the charged particles (pT > 0.5 GeV/c, |η| < 1) and form the charged particle density,
¨
dNchg/dηdφ, and the charged scalar pT sum density, dPTsum/dηdφ, by dividing by the area in η-φ
space.
Study the calorimeter towers (ET > 0.1 GeV, |η| < 1) and form the scalar ET sum density,
dETsum/dηdφ.
LHC/CMS Journal Club
November 30, 2005
Rick Field - Florida/CMS/CDF
Page 5
CDF Run 1 PT(Z)
PYTHIA 6.2 CTEQ5L
ISR Parameter
Parameter
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
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
Z-Boson Transverse Momentum
σ = 1.0
0.12
PT Distribution 1/N dN/dPT
UE Parameters
CDF Run 1 Data
PYTHIA Tune A
σ = 2.5
PYTHIA Tune A25
PYTHIA Tune A50
0.08
CDF Run 1
published
1.8 TeV
σ = 5.0
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),
Tune A25 (<pT(Z)> = 10.1 GeV/c), and
Tune A50 (<pT(Z)> = 11.2 GeV/c).
Intrensic KT
LHC/CMS Journal Club
November 30, 2005
Rick Field - Florida/CMS/CDF
Page 6
20
CDF Run 1 PT(Z)
PYTHIA 6.2 CTEQ5L
Parameter
Tune AW
Z-Boson Transverse Momentum
0.12
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
¨ 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).
MSTP(91)
1
1
Effective Q cut-off, below which space-like showers are not evolved.
PARP(91)
1.0
2.1
PARP(93)
5.0
15.0
PT Distribution 1/N dN/dPT
UE Parameters
Tune A
CDF Run 1 Data
PYTHIA Tune AW
0.08
CDF Run 1
published
σ = 2.1
1.8 TeV
Normalized to 1
0.04
0.00
ISR Parameters
Intrensic KT
LHC/CMS Journal Club
November 30, 2005
0
2
4
6
8
10
12
14
16
18
20
Z-Boson PT (GeV/c)
The Q2 = kT2 in αs for space-like showers is scaled by PARP(64)!
Rick Field - Florida/CMS/CDF
Page 7
Drell-Yan Production
at CDF
Drell-Yan Production
Lepton-Pair
Lepton-Pair Transverse
Momentum
Proton
<PT(pair)> versus M(pair)
PT(pair)
AntiProton
Underlying Event
Underlying Event
Initial-State
Radiation
Final-State
Radiation
Outgoing Parton
Lepton-Pair Transverse Momentum
Lepton-Pair Transverse Momentum
20
20
RDF Preliminary
RDF Preliminary
PY Tune AW
Average Pair PT
Average Pair PT
15
10
PY Tune A
5
Drell-Yan
1.96 TeV
Z
HERWIG
generator level
generator level
15
10
PY Tune AW
5
Drell-Yan
1.96 TeV
Z
0
0
0
50
100
150
200
250
0
50
Lepton-Pair Invariant Mass (GeV)
100
150
200
250
Lepton-Pair Invariant Mass (GeV)
¨ Shows the lepton-pair average PT versus the ¨ Shows the lepton-pair average PT versus the
lepton-pair invariant mass at 1.96 TeV for
lepton-pair invariant mass at 1.96 TeV for
PYTHIA Tune AW and HERWIG.
PYTHIA Tune AW and PYTHIA Tune A.
LHC/CMS Journal Club
November 30, 2005
Rick Field - Florida/CMS/CDF
Page 8
Drell-Yan Production
at CMS
Drell-Yan Production
Lepton-Pair
Lepton-Pair Transverse
Momentum
Proton
<PT(pair)> versus M(pair)
PT(pair)
AntiProton
Underlying Event
The lepton-pair <PT>
much larger at the LHC!
Underlying Event
Initial-State
Radiation
Final-State
Radiation
Outgoing Parton
Lepton-Pair Transverse Momentum
Lepton-Pair Transverse Momentum
40
20
RDF Preliminary
HERWIG
RDF Preliminary
15
10
Average Pair PT
Average Pair PT
LHC
generator level
generator level
PY Tune AW
5
30
HERWIG
10
Drell-Yan
1.96 TeV
Z
CDF
20
Z
PY Tune AW
Drell-Yan
0
0
0
50
100
150
200
250
0
50
100
150
200
250
Lepton-Pair Invariant Mass (GeV)
Lepton-Pair Invariant Mass (GeV)
¨ Shows the lepton-pair average PT versus the ¨ Shows the lepton-pair average PT versus the
lepton-pair invariant mass at 14 TeV for
lepton-pair invariant mass at 1.96 TeV for
PYTHIA Tune AW and HERWIG.
PYTHIA Tune AW and HERWIG.
LHC/CMS Journal Club
November 30, 2005
Rick Field - Florida/CMS/CDF
Page 9
The “Underlying Event” in
Drell-Yan Production (CDF)
Drell-Yan Production
Lepton
The “Underlying Event”
Proton
Underlying Event
Charged particle density
versus M(pair)
AntiProton
Underlying Event
HERWIG (without MPI)
is much less active than
PY Tune AW (with MPI)!
Initial-State
Radiation
Anti-Lepton
Charged Particle Density: dN/dηdφ
Charged Particle Density: dN/dηdφ
1.0
RDF Preliminary
generator level
0.8
Charged Particle Density
Charged Particle Density
1.0
PY Tune AW
0.6
0.4
PY Tune A
Drell-Yan
1.96 TeV
0.2
0.0
0
50
Z
100
Charged Particles (|η|<1.0, PT>0.5 GeV/c)
150
200
250
RDF Preliminary
generator level
0.8
PY Tune AW
0.6
0.4
HERWIG
0.2
Drell-Yan
1.96 TeV
Z
Charged Particles (|η|<1.0, PT>0.5 GeV/c)
(excluding lepton-pair )
0.0
0
50
Lepton-Pair Invariant Mass (GeV)
100
150
200
250
Lepton-Pair Invariant Mass (GeV)
¨ Shows the charged particle density versus the ¨ Shows the charged particle density versus the
lepton-pair invariant mass at 1.96 TeV for
lepton-pair invariant mass at 1.96 TeV for
PYTHIA Tune AW and PYTHIA Tune A.
PYTHIA Tune AW and HERWIG (with no MPI).
LHC/CMS Journal Club
November 30, 2005
Rick Field - Florida/CMS/CDF
Page 10
The “Underlying Event” in
Drell-Yan Production (CMS)
Drell-Yan Production
Lepton
The “Underlying Event”
HERWIG (without MPI)
is much less active than
PY Tune AW (with MPI)!
Proton
Underlying Event
Charged particle density
versus M(pair)
AntiProton
Underlying Event
“Underlying event” much
more active at the LHC!
Initial-State
Radiation
Anti-Lepton
Charged Particle Density: dN/dηdφ
Charged Particle Density: dN/dηdφ
1.5
RDF Preliminary
RDF Preliminary
generator level
0.8
PY Tune AW
0.6
0.4
HERWIG
0.2
Drell-Yan
1.96 TeV
Z
Charged Particles (|η|<1.0, PT>0.5 GeV/c)
(excluding lepton-pair )
Charged Particle Density
Charged Particle Density
1.0
LHC
generator level
1.0
PY Tune AW
CDF
0.5
Drell-Yan
Charged Particles (|η|<1.0, PT>0.5 GeV/c)
(excluding lepton-pair )
HERWIG
0.0
0.0
0
50
100
150
200
250
0
50
100
150
200
250
Lepton-Pair Invariant Mass (GeV)
Lepton-Pair Invariant Mass (GeV)
¨ Charged particle density versus the lepton- ¨ Charged particle density versus the lepton-pair
pair invariant mass at 1.96 TeV for PYTHIA invariant mass at 14 TeV for PYTHIA Tune AW
and HERWIG (without MPI).
Tune AW and HERWIG (without MPI).
LHC/CMS Journal Club
November 30, 2005
Rick Field - Florida/CMS/CDF
Page 11
The “Underlying Event” in
Drell-Yan Production (CDF)
Drell-Yan Production
Lepton
The “Underlying Event”
Proton
Underlying Event
Charged PTsum density
versus M(pair)
AntiProton
Underlying Event
HERWIG (without MPI)
is much less active than
PY Tune AW (with MPI)!
Initial-State
Radiation
Anti-Lepton
Charged PTsum Density: dPT/dηdφ
Charged PTsum Density: dPT/dηdφ
1.6
RDF Preliminary
Charged PTsum Density (GeV/c)
Charged PTsum Density (GeV/c)
1.6
generator level
1.2
PY Tune AW
0.8
PY Tune A
0.4
Drell-Yan
1.96 TeV
0.0
Z
Charged Particles (|η|<1.0, PT>0.5 GeV/c)
RDF Preliminary
generator level
1.2
PY Tune AW
Drell-Yan
1.96 TeV
0.8
0.4
Charged Particles (|η|<1.0, PT>0.5 GeV/c)
(excluding lepton-pair )
HERWIG
0.0
0
50
100
150
200
250
0
Lepton-Pair Invariant Mass (GeV)
50
100
150
200
250
Lepton-Pair Invariant Mass (GeV)
¨ Shows the charged PTsum density versus the ¨ Shows the charged PTsum density versus the
lepton-pair invariant mass at 1.96 TeV for
lepton-pair invariant mass at 1.96 TeV for
PYTHIA Tune AW and PYTHIA Tune A.
PYTHIA Tune AW and HERWIG (without MPI).
LHC/CMS Journal Club
November 30, 2005
Rick Field - Florida/CMS/CDF
Page 12
The “Underlying Event” in
Drell-Yan Production (CMS)
Drell-Yan Production
Lepton
The “Underlying Event”
HERWIG (without MPI)
is much less active than
PY Tune AW (with MPI)!
Proton
Underlying Event
Charged PTsum density
versus M(pair)
AntiProton
Underlying Event
“Underlying event” much
more active at the LHC!
Initial-State
Radiation
Anti-Lepton
Charged PTsum Density: dPT/dηdφ
Charged PTsum Density: dPT/dηdφ
2.5
RDF Preliminary
generator level
1.2
PY Tune AW
Drell-Yan
1.96 TeV
0.8
0.4
Charged Particles (|η|<1.0, PT>0.5 GeV/c)
(excluding lepton-pair )
HERWIG
0.0
Charged PTsum Density (GeV/c)
Charged PTsum Density (GeV/c)
1.6
RDF Preliminary
generator level
2.0
Drell-Yan
1.5
HERWIG
1.0
CDF
0.5
Z
0.0
0
50
100
150
200
250
LHC
PY Tune AW
0
Lepton-Pair Invariant Mass (GeV)
50
100
Charged Particles (|η|<1.0, PT>0.5 GeV/c)
(excluding lepton-pair )
150
200
250
Lepton-Pair Invariant Mass (GeV)
¨ Charged PTsum density versus the lepton-pair ¨ Charged PTsum density versus the leptonpair invariant mass at 14 TeV for PYTHIA
invariant mass at 1.96 TeV for PYTHIA Tune
Tune AW and HERWIG (without MPI).
AW and HERWIG (without MPI).
LHC/CMS Journal Club
November 30, 2005
Rick Field - Florida/CMS/CDF
Page 13
The “Underlying Event” in
Drell-Yan Production (CMS)
Drell-Yan Production
Lepton
The “Underlying Event”
Proton
ETsum density versus M(pair)
AntiProton
Underlying Event
Underlying Event
Initial-State
Radiation
Anti-Lepton
Transverse Energy Density: dET/dηdφ
Transverse Energy Density: dET/dηdφ
2.0
5.0
RDF Preliminary
RDF Preliminary
ETsum Density (GeV)
ETsum Density (GeV)
generator level
1.5
PY Tune AW
1.0
HERWIG
0.5
Drell-Yan
1.96 TeV
Z
0.0
0
50
100
All Particles (|η|<1.0, all PT)
(excluding lepton-pair )
150
200
generator level
4.0
3.0
HERWIG
2.0
CDF
1.0
Drell-Yan
0.0
250
LHC
PY Tune AW
0
50
All Particles (|η|<1.0, all PT)
(excluding lepton-pair )
Z
100
150
200
250
Lepton-Pair Invariant Mass (GeV)
Lepton-Pair Invariant Mass (GeV)
¨ ETsum density versus the lepton-pair
¨ ETsum density versus the lepton-pair invariant
invariant mass at 1.96 TeV for PYTHIA Tune
mass at 14 TeV for PYTHIA Tune AW and
AW and HERWIG (without MPI).
HERWIG (without MPI).
LHC/CMS Journal Club
November 30, 2005
Rick Field - Florida/CMS/CDF
Page 14
The “Underlying Event”
Drell-Yan vs Jets at CDF
The “Underlying Event” in High PT Lepton-Pair and Jet Production
Charged Particle Density: dN/dηdφ
Charged PTsum Density: dPT/dηdφ
1.0
PY Tune AW
Charged Particle Density
RDF Preliminary
"Leading Jet"
generator level
0.8
Charged PTsum Density (GeV/c)
1.6
0.6
Drell-Yan
0.4
HERWIG
0.2
Charged Particles (|η|<1.0, PT>0.5 GeV/c)
(excluding lepton-pair )
1.96 TeV
0.0
RDF Preliminary
"Leading Jet"
generator level
1.2
1.96 TeV
PY Tune AW
0.8
Drell-Yan
0.4
Charged Particles (|η|<1.0, PT>0.5 GeV/c)
(excluding lepton-pair )
HERWIG
0.0
0
50
100
150
200
250
300
350
400
450
500
0
50
100
PT(jet#1) or Lepton-Pair Mass
150
200
250
350
400
450
500
PT(jet#1) or Lepton-Pair Mass
2π
2π
Lepton
300
Away Region
Jet #1 Direction
∆φ
Transverse
Region
“Toward”
“Central Region”
φ
φ
Central Region
“Transverse”
Leading
Jet
“Transverse”
Toward Region
Transverse
Region
“Away”
Anti-Lepton
Drell-Yan
LHC/CMS Journal Club
November 30, 2005
0
-1
η
+1
“Leading Jet”
Rick Field - Florida/CMS/CDF
Away Region
0
-1
η
+1
Page 15
The “Underlying Event” in
High PT Jet Production (CMS)
The “Underlying Event”
High PT Jet Production
Charged particle density
versus PT(jet#1)
AntiProton
Outgoing Parton
PT(hard)
Initial-State
Radiation
Proton
Underlying Event
Underlying Event
Final-State
Radiation
Outgoing Parton
"Transverse" Charged Particle Density: dN/dηdφ
"Transverse" Charged Particle Density: dN/dηdφ
2.0
RDF Preliminary
generator level
0.8
0.6
PY Tune AW
HERWIG
0.4
1.96 TeV
0.2
"Leading Jet"
Charged Particles (|η|<1.0, PT>0.5 GeV/c)
0.0
"Transverse" Charged Density
"Transverse" Charged Density
1.0
“Underlying event” much
more active at the LHC!
LHC
RDF Preliminary
generator level
1.5
PY Tune AW
HERWIG
1.0
CDF
0.5
"Leading Jet"
Charged Particles (|η|<1.0, PT>0.5 GeV/c)
0.0
0
50
100
150
200
250
300
350
400
450
500
0
250
500
PT(particle jet#1) (GeV/c)
750
1000
1250
1500
1750
2000
2250
2500
PT(particle jet#1) (GeV/c)
¨ Charged particle density in the “Transverse” ¨ Charged particle density in the “Transverse”
region versus PT(jet#1) at 1.96 TeV for PY
region versus PT(jet#1) at 14 TeV for PY Tune
Tune AW and HERWIG (without MPI).
AW and HERWIG (without MPI).
LHC/CMS Journal Club
November 30, 2005
Rick Field - Florida/CMS/CDF
Page 16
The “Underlying Event” in
High PT Jet Production (CMS)
The “Underlying Event”
High PT Jet Production
PT(hard)
Initial-State
Radiation
Proton
Underlying Event
Underlying Event
“Underlying event” much
more active at the LHC!
Final-State
Radiation
Outgoing Parton
"Transverse" PTsum Density: dPT/dηdφ
"Transverse" PTsum Density: dPT/dηdφ
RDF Preliminary
generator level
1.5
PY Tune AW
"Leading Jet"
1.0
HERWIG
0.5
1.96 TeV
Charged Particles (|η|<1.0, PT>0.5 GeV/c)
"Transverse" PTsum Density (GeV/c)
8.0
2.0
"Transverse" PTsum Density (GeV/c)
Charged PTsum density versus
PT(jet#1)
AntiProton
Outgoing Parton
RDF Preliminary
LHC
PY Tune AW
generator level
6.0
"Leading Jet"
HERWIG
4.0
2.0
CDF
Charged Particles (|η|<1.0, PT>0.5 GeV/c)
0.0
0.0
0
50
100
150
200
250
300
350
400
450
500
0
250
500
750
1000
1250
1500
1750
2000
2250
2500
PT(particle jet#1) (GeV/c)
PT(particle jet#1) (GeV/c)
¨ Charged PTsum density in the “Transverse” ¨ Charged PTsum density in the “Transverse”
region versus PT(jet#1) at 1.96 TeV for PY
region versus PT(jet#1) at 14 TeV for PY Tune
Tune AW and HERWIG (without MPI).
AW and HERWIG (without MPI)..
LHC/CMS Journal Club
November 30, 2005
Rick Field - Florida/CMS/CDF
Page 17
The “Underlying Event” in
High PT Jet Production (CMS)
The “Underlying Event”
High PT Jet Production
Outgoing Parton
PT(hard)
Initial-State
Radiation
Proton
AntiProton
Underlying Event
Underlying Event
Outgoing Parton
“Underlying event” much
more active at the LHC!
Final-State
Radiation
"Transverse" ETsum Density: dET/dηdφ
"Transverse" ETsum Density: dET/dηdφ
4.0
14.0
RDF Preliminary
generator level
"Transverse" ETsum Density (GeV)
"Transverse" ETsum Density (GeV)
ETsum density versus PT(jet#1)
PY Tune AW
3.0
"Leading Jet"
2.0
HERWIG
1.0
1.96 TeV
All Particles (|η|<1.0, all PT)
0.0
RDF Preliminary
12.0
LHC
PY Tune AW
generator level
10.0
"Leading Jet"
8.0
HERWIG
6.0
4.0
2.0
CDF
All Particles (|η|<1.0, all PT)
0.0
0
50
100
150
200
250
300
350
400
450
500
0
250
PT(particle jet#1) (GeV/c)
500
750
1000
1250
1500
1750
2000
2250
2500
PT(particle jet#1) (GeV/c)
¨ ETsum density in the “Transverse” region
¨ ETsum density in the “Transverse” region
versus PT(jet#1) at 1.96 TeV for PY Tune AW versus PT(jet#1) at 14 TeV for PY Tune AW
and HERWIG (without MPI).
and HERWIG (without MPI).
LHC/CMS Journal Club
November 30, 2005
Rick Field - Florida/CMS/CDF
Page 18
The “Underlying Event”
Drell-Yan vs Jets at CMS
The “Underlying Event” in High PT Lepton-Pair and Jet Production
Charged PTsum Density: dPT/dηdφ
Charged Particle Density: dN/dηdφ
"Leading Jet"
Charged Particle Density
RDF Preliminary
generator level
1.5
PY Tune AW
HERWIG
1.0
14 TeV
0.5
Drell-Yan
Charged Particles (|η|<1.0, PT>0.5 GeV/c)
(excluding lepton-pair )
0.0
Charged PTsum Density (GeV/c)
8.0
2.0
RDF Preliminary
"Leading Jet"
PY Tune AW
generator level
6.0
HERWIG
4.0
14 TeV
2.0
Charged Particles (|η|<1.0, PT>0.5 GeV/c)
(excluding lepton-pair )
Drell-Yan
0.0
0
250
500
750
1000
1250
1500
1750
2000
2250
2500
0
250
500
750
PT(jet#1) orLepton-Pair Mass
1000
1250
1750
2000
2250
2500
PT(jet#1) or Lepton-Pair Mass
2π
2π
Lepton
1500
Away Region
Jet #1 Direction
∆φ
Transverse
Region
“Toward”
“Central Region”
φ
φ
Central Region
“Transverse”
Leading
Jet
“Transverse”
Toward Region
Transverse
Region
“Away”
Anti-Lepton
Drell-Yan
LHC/CMS Journal Club
November 30, 2005
0
-1
η
+1
“Leading Jet”
Rick Field - Florida/CMS/CDF
Away Region
0
-1
η
+1
Page 19
UE&MB@CMS
“Minimum-Bias” Collisions
Proton
Proton
High PT Jet Production
Outgoing Parton
PT(hard)
Initial-State
Radiation
Proton
¨ 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
Underlying Event
Outgoing Parton
Underlying Event
Final-State
Radiation
Drell-Yan Production
Lepton
Proton
¨ “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)
Proton
Underlying Event
Underlying Event
Initial-State
Radiation
Anti-Lepton
Drell-Yan Production
Lepton-Pair
PT(pair)
Proton
Proton
Underlying Event
Underlying Event
¨ Drell-Yan Studies: Transverse momentum distribution of
the lepton-pair versus the mass of the lepton-pair,
<pT(pair)>, <pT2(pair)>, dσ/dpT(pair) (only requires
muons). Event structure for large lepton-pair pT (i.e. µµ
+jets, requires muons and calorimeter).
Initial-State
Radiation
Final-State
Radiation
Outgoing Parton
LHC/CMS Journal Club
November 30, 2005
Rick Field - Florida/CMS/CDF
Page 20
UE&MB@CMS
“Minimum-Bias” Collisions
Proton
Proton
High PT Jet Production
Outgoing Parton
PT(hard)
Initial-State
Radiation
Proton
Proton
Underlying Event
Outgoing Parton
Underlying Event
Final-State
Radiation
Drell-Yan Production
Lepton
Proton
Proton
Underlying Event
Underlying Event
Initial-State
Radiation
Anti-Lepton
Drell-Yan Production
Lepton-Pair
PT(pair)
Proton
Proton
Underlying Event
Underlying Event
¨ 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)
UE&MB@CMS
¨ “Underlying
Event” Studies: The “transverse region” in
Rick
Field
“leading
Jet”
and(Florida)
“back-to-back” jet production. The
Darin
Acosta
(Florida)
“central region” in Drell-Yan production. (requires charged
Albert De Roeck (CERN)
tracks and calorimeter and muons for Drell-Yan)
Paolo Bartalini (UF Postdoc at CERN)
Livio Fano' (INFN/Perugia at CERN)
Filippo Ambroglini (INFN/Perugia at CERN)
¨ Drell-Yan Studies: Transverse momentum distribution of
the lepton-pair versus the mass of the lepton-pair,
<pT(pair)>, <pT2(pair)>, dσ/dpT(pair) (only requires
muons). Event structure for large lepton-pair pT (i.e. µµ
+jets, requires muons and calorimeter).
Initial-State
Radiation
Final-State
Radiation
Outgoing Parton
LHC/CMS Journal Club
November 30, 2005
Rick Field - Florida/CMS/CDF
Page 21