Upload
moris-carroll
View
217
Download
0
Embed Size (px)
DESCRIPTION
MCnet07 - Durham - Part 1 April 18-20, 2007 Rick Field – Florida/CDF/CMSPage 3 “Feynman-Field Jet Model” The Feynman-Field Days FF1: “Quark Elastic Scattering as a Source of High Transverse Momentum Mesons”, R. D. Field and R. P. Feynman, Phys. Rev. D15, (1977). FFF1: “Correlations Among Particles and Jets Produced with Large Transverse Momenta”, R. P. Feynman, R. D. Field and G. C. Fox, Nucl. Phys. B128, 1-65 (1977). FF2: “A Parameterization of the properties of Quark Jets”, R. D. Field and R. P. Feynman, Nucl. Phys. B136, 1-76 (1978). F1: “Can Existing High Transverse Momentum Hadron Experiments be Interpreted by Contemporary Quantum Chromodynamics Ideas?”, R. D. Field, Phys. Rev. Letters 40, (1978). FFF2: “A Quantum Chromodynamic Approach for the Large Transverse Momentum Production of Particles and Jets”, R. P. Feynman, R. D. Field and G. C. Fox, Phys. Rev. D18, (1978) FW1: “A QCD Model for e + e - Annihilation”, R. D. Field and S. Wolfram, Nucl. Phys. B213, (1983). My 1 st graduate student!
Citation preview
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 1
Physics and Techniques Physics and Techniques of Event Generatorsof Event Generators
Rick FieldUniversity of Florida
(for the CDF & CMS Collaborations)
CDF Run 2
Min-Bias and the Underlying Eventat the TEVATRON and the LHC
CMS at the LHC
UE&MB@CMSUE&MB@CMS1st Lecture
IPPP Durham, April 18-20, 2007
The early days of event generators.
Proton AntiProton
PT(hard)
Outgoing Parton
Outgoing Parton
Underlying Event Underlying Event
Initial-State Radiation
Final-State Radiation
“Min-Bias” at the Tevatron.
Studying the “underlying event” in Run 1 at CDF.
and extrapolations to the LHC.
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 2
Toward and Understanding of Toward and Understanding of Hadron-Hadron CollisionsHadron-Hadron Collisions
From 7 GeV/c 0’s to 600 GeV/c Jets. The early days of trying to understand and simulate hadron-hadron collisions.
Feynman-Field Phenomenology
Feynman and Field
Proton AntiProton
PT(hard)
Outgoing Parton
Outgoing Parton
Underlying Event Underlying Event
Initial-State Radiation
Final-State Radiation
1st hat!
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 3
“Feynman-Field Jet Model”
The FeynmanThe Feynman-Field -Field DaysDays
FF1: “Quark Elastic Scattering as a Source of High Transverse Momentum Mesons”, R. D. Field and R. P. Feynman, Phys. Rev. D15, 2590-2616 (1977).
FFF1: “Correlations Among Particles and Jets Produced with Large Transverse Momenta”, R. P. Feynman, R. D. Field and G. C. Fox, Nucl. Phys. B128, 1-65 (1977).
FF2: “A Parameterization of the properties of Quark Jets”, R. D. Field and R. P. Feynman, Nucl. Phys. B136, 1-76 (1978).
F1: “Can Existing High Transverse Momentum Hadron Experiments be Interpreted by Contemporary Quantum Chromodynamics Ideas?”, R. D. Field, Phys. Rev. Letters 40, 997-1000 (1978).
FFF2: “A Quantum Chromodynamic Approach for the Large Transverse Momentum Production of Particles and Jets”, R. P. Feynman, R. D. Field and G. C. Fox, Phys. Rev. D18, 3320-3343 (1978).
1973-1983
FW1: “A QCD Model for e+e- Annihilation”, R. D. Field and S. Wolfram, Nucl. Phys. B213, 65-84 (1983).
My 1st graduate student!
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 4
Hadron-Hadron CollisionsHadron-Hadron Collisions
What happens when two hadrons collide at high energy?
Most of the time the hadrons ooze through each other and fall apart (i.e. no hard scattering). The outgoing particles continue in roughly the same direction as initial proton and antiproton.
Occasionally there will be a large transverse momentum meson. Question: Where did it come from?
We assumed it came from quark-quark elastic scattering, but we did not know how to calculate it!
Hadron Hadron ???
Hadron Hadron
“Soft” Collision (no large transverse momentum)
Hadron Hadron
high PT meson
Parton-Parton Scattering Outgoing Parton
Outgoing Parton
FF1 1977 (preQCD)
Feynman quote from FF1“The model we shall choose is not a popular one,
so that we will not duplicate too much of thework of others who are similarly analyzing various models (e.g. constituent interchange
model, multiperipheral models, etc.). We shall assume that the high PT particles arise from direct hard collisions between constituent quarks in the incoming particles, which
fragment or cascade down into several hadrons.”
“Black-Box Model”
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 5
QuarkQuark--Quark BlackQuark Black--Box ModelBox ModelFF1 1977 (preQCD)Quark Distribution Functions
determined from deep-inelasticlepton-hadron collisions
Quark Fragmentation Functionsdetermined from e+e- annihilationsQuark-Quark Cross-Section
Unknown! Deteremined fromhadron-hadron collisions.
No gluons!
Feynman quote from FF1“Because of the incomplete knowledge of
our functions some things can be predicted with more certainty than others. Those experimental results that are not well
predicted can be “used up” to determine these functions in greater detail to permit better predictions of further experiments. Our papers will be a bit long because we wish to discuss this interplay in detail.”
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 6
Quark-Quark Black-Box ModelQuark-Quark Black-Box Model
FF1 1977 (preQCD)Predictparticle ratios
Predictincrease with increasing
CM energy W
Predictoverall event topology
(FFF1 paper 1977)
“Beam-Beam Remnants”
7 GeV/c 0’s!
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 7
QCD Approach: Quarks & GluonsQCD Approach: Quarks & Gluons
FFF2 1978
Parton Distribution FunctionsQ2 dependence predicted from
QCD
Quark & Gluon Fragmentation Functions
Q2 dependence predicted from QCD
Quark & Gluon Cross-SectionsCalculated from QCD
Feynman quote from FFF2“We investigate whether the present
experimental behavior of mesons with large transverse momentum in hadron-hadron
collisions is consistent with the theory of quantum-chromodynamics (QCD) with
asymptotic freedom, at least as the theory is now partially understood.”
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 8
High PHigh PTT Jets Jets
30 GeV/c!
Predictlarge “jet”
cross-section
Feynman, Field, & Fox (1978) CDF (2006)
600 GeV/c Jets!Feynman quote from FFF
“At the time of this writing, there is still no sharp quantitative test of QCD.
An important test will come in connection with the phenomena of high PT discussed here.”
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 9
Proton-AntiProton CollisionsProton-AntiProton Collisionsat the Tevatronat the Tevatron
Elastic Scattering Single Diffraction
M
tot = ELSD DD HC
Double Diffraction
M1 M2
Proton AntiProton
“Soft” Hard Core (no hard scattering)
Proton AntiProton
PT(hard)
Outgoing Parton
Outgoing Parton
Underlying Event Underlying Event Initial-State Radiation
Final-State Radiation
“Hard” Hard Core (hard scattering)
Hard Core
1.8 TeV: 78mb = 18mb + 9mb + (4-7)mb + (47-44)mb
The CDF “Min-Bias” trigger picks up most of the “hard
core” cross-section plus a small amount of single & double
diffraction.
The “hard core” component contains both “hard” and
“soft” collisions.
Beam-Beam Counters
3.2 < || < 5.9
CDF “Min-Bias” trigger1 charged particle in forward BBC
AND1 charged particle in backward BBC
tot = ELIN
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 10
No-Bias vs Min-BiasNo-Bias vs Min-BiasCharged Particle Density: dN/d
0
1
2
3
4
5
-8 -6 -4 -2 0 2 4 6 8
PseudoRapidity
Cha
rged
Par
ticle
Den
sity
pyDWT HC NoTrigpyDWT DD NoTtrigpyDWT SD NoTrig
No Trigger900 GeV Generated
Charged Particles (all PT)
Charged Particle Density: dN/d
0
1
2
3
4
5
-8 -6 -4 -2 0 2 4 6 8
PseudoRapidity
Cha
rged
Par
ticle
Den
sity
pyDW HC MbtrigpyDW DD MBtrigpyDW SD MBtrig
CDF Min-Bias Trigger900 GeV Generated
Charged Particles (all PT)
Charged Particle Density: dN/d
0
1
2
3
4
5
-8 -6 -4 -2 0 2 4 6 8
PseudoRapidity
Cha
rged
Par
ticle
Den
sity
pyDWT Sum NoTrigpyDWT HC NoTrigpyDWT DD NoTtrigpyDWT SD NoTrig
No Trigger900 GeV Weighted
Charged Particles (all PT)
Charged Particle Density: dN/d
0
1
2
3
4
5
-8 -6 -4 -2 0 2 4 6 8
PseudoRapidity
Cha
rged
Par
ticle
Den
sity
pyDWT Sum MBtrigpyDWT HC MBtrigpyDWT DD MBtrigpyDWT SD MBtrig
CDF Min-Bias Trigger900 GeV Weighted
Charged Particles (all PT)
What you see for “Min-Bias”depends on your triggger!
By comparing different“Min-Bias” triggers one canlearn about the components!
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 11
No-Bias vs Min-BiasNo-Bias vs Min-BiasCharged Particle Density: dN/d
0
1
2
3
4
-10 -8 -6 -4 -2 0 2 4 6 8 10
PseudoRapidity
Cha
rged
Par
ticle
Den
sity
PYTHIA Tune DWCharged Particles
No-Bias 1.96 TeV(HC+SD+DD+EL)
All PT
Charged Particle Density: dN/d
0
1
2
3
4
-10 -8 -6 -4 -2 0 2 4 6 8 10
PseudoRapidity
Cha
rged
Par
ticle
Den
sity
PYTHIA Tune DWCharged Particles
No-Bias 1.96 TeV(HC+SD+DD+EL)
All PTPT > 0.5 GeV/c
Charged Particle Density: dN/d
0.0
0.5
1.0
1.5
2.0
-10 -8 -6 -4 -2 0 2 4 6 8 10
PseudoRapidity
Cha
rged
Par
ticle
Den
sity
PYTHIA Tune DWCharged Particles (PT > 0.5 GeV/c) Min-Bias 1.96 TeV
(HC+SD+DD+EL)
CDF Min-Bias Trigger
No Trigger
Charged particle (all pT) pseudo-rapidity distribution, dNchg/dd, at 1.96 TeV with no trigger (i.e. no-bias) from PYTHIA Tune DW.
About 2.5 charged particles per unit at = 0.
About 0.9 charged particles (pT > 0.5 GeV/c) per unit at = 0.
Charged particle (pT > 0.5 GeV/c) pseudo-rapidity distribution, dNchg/dd, at 1.96 TeV with the CDF Min-Bias trigger from PYTHIA Tune DW.
About 1.5 charged particles (pT > 0.5 GeV/c) per unit at = 0 with CDF min-bias trigger.
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 12
60 cm
Charged Particle Density: dN/d
0
2
4
6
-8 -6 -4 -2 0 2 4 6 8
PseudoRapidity
Cha
rged
Par
ticle
Den
sity
pyDWT HC+SD+DD NoTrigpyDWT HC+SD+DD NoTrig 10mmCharged Particles (all PT)
Min-Bias 14 TeVPY Tune DWT
Min-Bias Particle TypesMin-Bias Particle Types
Using c = 10 mm reduces the charged particle density by almost 10%! Mostly from Ks→+- (68.6%) and →p-
(64.2%).
With c = 10mm With Stable Particles
charged particle density: 10mm vs Stable
This is a bigger effect than I expected! No-Bias at 14 TeV
Proton AntiProton
Primary
CDF Run 2
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 13
-1 +1
2
0
1 charged particle
dNchg/dd = 1/4 = 0.08
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.
Charged Particles pT > 0.5 GeV/c || < 1
= 4 = 12.6
1 GeV/c PTsum
dPTsum/dd = 1/4 GeV/c = 0.08 GeV/c
dNchg/dd = 3/4 = 0.24
3 charged particles
dPTsum/dd = 3/4 GeV/c = 0.24 GeV/c
3 GeV/c PTsum
CDF Run 2 “Min-Bias”Observable Average Average Density
per unit -
NchgNumber of Charged Particles
(pT > 0.5 GeV/c, || < 1) 3.17 +/- 0.31 0.252 +/- 0.025
PTsum (GeV/c)
Scalar pT sum of Charged Particles(pT > 0.5 GeV/c, || < 1) 2.97 +/- 0.23 0.236 +/- 0.018
Divide by 4
CDF Run 2 “Min-Bias”
Particle DensitiesParticle Densities
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 14
Shows CDF “Min-Bias” data on the number of charged particles per unit pseudo-rapidity at 630 and 1,800 GeV. There are about 4.2 charged particles per unit in “Min-Bias” collisions at 1.8 TeV (|| < 1, all pT).
Charged Particle Pseudo-Rapidity Distribution: dN/d
0
1
2
3
4
5
6
7
-4 -3 -2 -1 0 1 2 3 4
Pseudo-Rapidity
dN/d
CDF Min-Bias 1.8 TeVCDF Min-Bias 630 GeV all PT
CDF Published
<dNchg/d> = 4.2
Charged Particle Density: dN/dd
0.0
0.2
0.4
0.6
0.8
1.0
-4 -3 -2 -1 0 1 2 3 4
Pseudo-Rapidity
dN/d
d
CDF Min-Bias 630 GeVCDF Min-Bias 1.8 TeV all PT
CDF Published
<dNchg/dd> = 0.67
Convert to charged particle density, dNchg/dd by dividing by 2. There are about 0.67 charged particles per unit - in “Min-Bias” collisions at 1.8 TeV (|| < 1, all pT).
= 1
= 1
x = 1
0.67
There are about 0.25 charged particles per unit - in “Min-Bias” collisions at 1.96 TeV (|| < 1, pT > 0.5 GeV/c).
0.25
CDF Run 1 “Min-Bias” DataCDF Run 1 “Min-Bias” DataCharged Particle DensityCharged Particle Density
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 15
Charged Particle Density: dN/dd
0.0
0.2
0.4
0.6
0.8
1.0
-4 -3 -2 -1 0 1 2 3 4
Pseudo-Rapidity
dN/d
d
CDF Min-Bias 630 GeVCDF Min-Bias 1.8 TeV all PT
CDF Published
Shows the center-of-mass energy dependence of the charged particle density, dNchg/dd for “Min-Bias” collisions at = 0. Also show a log fit (Fit 1) and a (log)2 fit (Fit 2) to the CDF plus UA5 data.
Charged Particle Density: dN/dd
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
10 100 1,000 10,000 100,000CM Energy W (GeV)
Cha
rged
den
sity
dN
/d
d
CDF DataUA5 DataFit 2Fit 1
= 0
<dNchg/dd> = 0.51 = 0 630 GeV
What should we expect for the LHC?
<dNchg/dd> = 0.63 = 0 1.8 TeV
LHC?
24% increase
CDF Run 1 “MinCDF Run 1 “Min--Bias” DataBias” DataEnergy DependenceEnergy Dependence
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 16
Charged Particle Density: dN/dd
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
-6 -4 -2 0 2 4 6
Pseudo-Rapidity
dN/d
d
630 GeV1.8 TeV
Herwig "Soft" Min-Bias 14 TeV
all PT
Shows the center-of-mass energy dependence of the charged particle density, dNchg/dd for “Min-Bias” collisions compared with the HERWIG “Soft” Min-Bias Monte-Carlo model. Note: there is no “hard” scattering in HERWIG “Soft” Min-Bias.
HERWIG “Soft” Min-Bias contains no hard parton-parton interactions and describes fairly well the charged particle density, dNchg/dd, in “Min-Bias” collisions.
Charged Particle Density: dN/dd
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
10 100 1,000 10,000 100,000
CM Energy W (GeV)
Cha
rged
den
sity
dN
/d d
CDF DataUA5 DataFit 2Fit 1HW Min-Bias
= 0
HERWIG “Soft” Min-Bias predicts a 45% rise in dNchg/dd at = 0 in going from the Tevatron (1.8 TeV) to the LHC (14 TeV). 4 charged particles per unit becomes 6.
Can we believe HERWIG “soft” Min-Bias?
Can we believe HERWIG “soft” Min-Bias? No!
LHC?
Herwig “Soft” Min-BiasHerwig “Soft” Min-Bias
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 17
Charged Particle Density
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
1.0E+01
0 2 4 6 8 10 12 14
PT (GeV/c)C
harg
ed D
ensi
ty d
N/d
d
dPT
(1/G
eV/c
)
||<1CDF Preliminary
CDF Min-Bias Data at 1.8 TeV
HW "Soft" Min-Biasat 630 GeV, 1.8 TeV, and 14 TeV
Charged Particle Density: dN/dd
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
-6 -4 -2 0 2 4 6
Pseudo-Rapidity
dN/d
d
630 GeV1.8 TeV
Herwig "Soft" Min-Bias 14 TeV
all PT
Shows the pT dependence of the charged particle density, dNchg/dddPT, for “Min-Bias” collisions at 1.8 TeV collisions compared with HERWIG “Soft” Min-Bias.
HERWIG “Soft” Min-Bias does not describe the “Min-Bias” data! The “Min-Bias” data contains a lot of “hard” parton-parton collisions which results in many more particles at large PT than are produces by any “soft” model.
Shows the energy dependence of the charged particle density, dNchg/dd for “Min-Bias” collisions compared with HERWIG “Soft” Min-Bias.
Lots of “hard” scattering in “Min-Bias”!
HERWIG “Soft” Min-Bias
CDF Run 1 “Min-Bias” DataCDF Run 1 “Min-Bias” DatappTT Distribution Distribution
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 18
Charged Particle Density: dN/dd
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
-4 -3 -2 -1 0 1 2 3 4
Pseudo-Rapidity
dN/d
d
CDF Min-Bias Data Herwig Jet3 Herwig Min-Bias
1.8 TeV all PTHW "Soft" Min-Bias
HW PT(hard) > 3 GeV/c
Charged Particle Density
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
1.0E+01
0 2 4 6 8 10 12 14
PT (GeV/c)C
harg
ed D
ensi
ty d
N/d
d
dPT
(1/G
eV/c
)
Herwig Jet3Herwig Min-BiasCDF Min-Bias Data
1.8 TeV ||<1
CDF Preliminary
HW PT(hard) > 3 GeV/c
HW "Soft" Min-Bias
HERWIG “hard” QCD with PT(hard) > 3 GeV/c describes well the high pT tail but produces too many charged particles overall. Not all of the “Min-Bias” collisions have a hard scattering with PT(hard) > 3 GeV/c!
One cannot run the HERWIG “hard” QCD Monte-Carlo with PT(hard) < 3 GeV/c because the perturbative 2-to-2 cross-sections diverge like 1/PT(hard)4?
HERWIG “soft” Min-Bias does not fit the “Min-Bias” data!
Hard-Scattering Cross-Section
0.01
0.10
1.00
10.00
100.00
0 2 4 6 8 10 12 14 16 18 20Hard-Scattering Cut-Off PTmin
Cro
ss-S
ectio
n (m
illib
arns
)
PYTHIAHERWIG
CTEQ5L1.8 TeV
HC
PYTHIA cuts off the divergence.
Can run PT(hard)>0!
CDF Run 1 “Min-Bias” DataCDF Run 1 “Min-Bias” DataCombining “Soft” + “Hard”Combining “Soft” + “Hard” HERWIG diverges!
No easy way to“mix” HERWIG “hard” with HERWIG “soft”.
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 19
PYTHIA Tune A Min-BiasPYTHIA Tune A Min-Bias“Soft” + ”Hard”“Soft” + ”Hard”
Charged Particle Density: dN/dd
0.0
0.2
0.4
0.6
0.8
1.0
-4 -3 -2 -1 0 1 2 3 4
Pseudo-Rapidity
dN/d
d
Pythia 6.206 Set ACDF Min-Bias 1.8 TeV 1.8 TeV all PT
CDF Published
PYTHIA regulates the perturbative 2-to-2 parton-parton cross sections with cut-off parameters which allows one to run with PT(hard) > 0. One can simulate both “hard” and “soft” collisions in one program.
The relative amount of “hard” versus “soft” depends on the cut-off and can be tuned.
Charged Particle Density
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
0 2 4 6 8 10 12 14
PT(charged) (GeV/c)C
harg
ed D
ensi
ty d
N/d
d
dPT
(1/G
eV/c
)
Pythia 6.206 Set ACDF Min-Bias Data
CDF Preliminary
1.8 TeV ||<1
PT(hard) > 0 GeV/c
Tuned to fit the CDF Run 1 “underlying event”!
12% of “Min-Bias” events have PT(hard) > 5 GeV/c!
1% of “Min-Bias” events have PT(hard) > 10 GeV/c!
This PYTHIA fit predicts that 12% of all “Min-Bias” events are a result of a hard 2-to-2 parton-parton scattering with PT(hard) > 5 GeV/c (1% with PT(hard) > 10 GeV/c)!
Lots of “hard” scattering in “Min-Bias” at the Tevatron!
PYTHIA Tune ACDF Run 2 Default
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 20
Use the maximum pT charged particle in the event, PTmax, to define a direction and look at the the “associated” density, dNchg/dd, in “min-bias” collisions (pT > 0.5 GeV/c, || < 1).
PTmax Direction
Correlations in
Charged Particle Density: dN/dd
0.0
0.1
0.2
0.3
0.4
0.5
0 30 60 90 120 150 180 210 240 270 300 330 360 (degrees)
Cha
rged
Par
ticle
Den
sity
PTmax
Associated DensityPTmax not included
CDF Preliminarydata uncorrected
Charged Particles (||<1.0, PT>0.5 GeV/c)
Charge Density
Min-Bias
“Associated” densities do not include PTmax!
Highest pT charged particle!
PTmax Direction
Correlations in
Shows the data on the dependence of the “associated” charged particle density, dNchg/dd, for charged particles (pT > 0.5 GeV/c, || < 1, not including PTmax) relative to PTmax (rotated to 180o) for “min-bias” events. Also shown is the average charged particle density, dNchg/dd, for “min-bias” events.
It is more probable to find a particle accompanying PTmax than it is to
find a particle in the central region!
CDF Run 2 Min-Bias “Associated”CDF Run 2 Min-Bias “Associated”Charged Particle DensityCharged Particle Density
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 21
Associated Particle Density: dN/dd
0.0
0.2
0.4
0.6
0.8
1.0
0 30 60 90 120 150 180 210 240 270 300 330 360 (degrees)
Ass
ocia
ted
Part
icle
Den
sity
PTmax > 2.0 GeV/cPTmax > 1.0 GeV/cPTmax > 0.5 GeV/c
CDF Preliminarydata uncorrected
PTmaxPTmax not included
Charged Particles (||<1.0, PT>0.5 GeV/c)
Min-Bias
PTmax Direction
Correlations in
Shows the data on the dependence of the “associated” charged particle density, dNchg/dd, for charged particles (pT > 0.5 GeV/c, || < 1, not including PTmax) relative to PTmax (rotated to 180o) for “min-bias” events with PTmax > 0.5, 1.0, and 2.0 GeV/c.
Transverse Region
Transverse Region
Jet #1
Shows “jet structure” in “min-bias” collisions (i.e. the “birth” of the leading two jets!).
Jet #2
Ave Min-Bias0.25 per unit -
PTmax Direction
“Toward”
“Transverse” “Transverse”
“Away”
PTmax > 0.5 GeV/c
PTmax > 2.0 GeV/c
CDF Run 2 Min-Bias “Associated”CDF Run 2 Min-Bias “Associated”Charged Particle DensityCharged Particle Density Rapid rise in the particle
density in the “transverse” region as PTmax increases!
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 22
Shows the data on the dependence of the “associated” charged particle density, dNchg/dd, for charged particles (pT > 0.5 GeV/c, || < 1, not including PTmax) relative to PTmax (rotated to 180o) for “min-bias” events with PTmax > 0.5 GeV/c and PTmax > 2.0 GeV/c compared with PYTHIA Tune A (after CDFSIM).
PTmax Direction
Correlations in
Associated Particle Density: dN/dd
0.0
0.2
0.4
0.6
0.8
1.0
0 30 60 90 120 150 180 210 240 270 300 330 360 (degrees)
Ass
ocia
ted
Part
icle
Den
sity
PTmax > 2.0 GeV/cPY Tune APTmax > 0.5 GeV/cPY Tune A
CDF Preliminarydata uncorrectedtheory + CDFSIM
PTmaxPTmax not included (||<1.0, PT>0.5 GeV/c)
PY Tune A 1.96 TeV
PYTHIA Tune A predicts a larger correlation than is seen in the “min-bias” data (i.e. Tune A “min-bias” is a bit too “jetty”).
PTmax > 2.0 GeV/c
PTmax > 0.5 GeV/c
PTmax Direction
“Toward”
“Transverse” “Transverse”
“Away”
Transverse Region Transverse
Region
PY Tune A
CDF Run 2 Min-Bias “Associated”CDF Run 2 Min-Bias “Associated”Charged Particle DensityCharged Particle Density
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 23
Charged Particle Density: dN/dd
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
-6 -4 -2 0 2 4 6
Pseudo-Rapidity
dN/d
d
all PT
CDF Data Pythia 6.206 Set A
630 GeV
1.8 TeV
14 TeV
PYTHIA was tuned to fit the “underlying event” in hard-scattering processes at 1.8 TeV and 630 GeV.
Charged Particle Density: dN/dd
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
10 100 1,000 10,000 100,000CM Energy W (GeV)
Cha
rged
den
sity
dN
/d
d
Pythia 6.206 Set ACDF DataUA5 DataFit 2Fit 1
= 0
Shows the center-of-mass energy dependence of the charged particle density, dNchg/dd for “Min-Bias” collisions compared with PYTHIA Tune A with PT(hard) > 0.
PYTHIA Tune A predicts a 42% rise in dNchg/dd at = 0 in going from the Tevatron (1.8 TeV) to the LHC (14 TeV). Similar to HERWIG “soft” min-bias, 4 charged particles per unit becomes 6.
LHC?
PYTHIA Tune APYTHIA Tune ALHC Min-Bias PredictionsLHC Min-Bias Predictions
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 24
Charged Particle Density
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
0 2 4 6 8 10 12 14
PT(charged) (GeV/c)
Cha
rged
Den
sity
dN
/d
ddP
T (1
/GeV
/c)
CDF Data
||<1
630 GeV
Pythia 6.206 Set A
1.8 TeV
14 TeV
Hard-Scattering in Min-Bias Events
0%
10%
20%
30%
40%
50%
100 1,000 10,000 100,000CM Energy W (GeV)
% o
f Eve
nts
PT(hard) > 5 GeV/cPT(hard) > 10 GeV/c
Pythia 6.206 Set A
Shows the center-of-mass energy dependence of the charged particle density, dNchg/dddPT, for “Min-Bias” collisions compared with PYTHIA Tune A with PT(hard) > 0.
PYTHIA Tune A predicts that 1% of all “Min-Bias” events at 1.8 TeV are a result of a hard 2-to-2 parton-parton scattering with PT(hard) > 10 GeV/c which increases to 12% at 14 TeV!
1% of “Min-Bias” events have PT(hard) > 10 GeV/c!
12% of “Min-Bias” events have PT(hard) > 10 GeV/c!
LHC?
PYTHIA Tune APYTHIA Tune ALHC Min-Bias PredictionsLHC Min-Bias Predictions
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 25
PYTHIA Tune A and Tune DW predict about 6 charged particles per unit at = 0, while the ATLAS tune predicts around 9.
Shows the predictions of PYTHIA Tune A, Tune DW, Tune DWT, and the ATLAS tune for the charged particle density dN/d and dN/dY at 14 TeV (all pT).
PYTHIA Tune DWT is identical to Tune DW at 1.96 TeV, but extrapolates to the LHC using the ATLAS energy dependence.
Charged Particle Density: dN/d
0
2
4
6
8
10
-10 -8 -6 -4 -2 0 2 4 6 8 10
PseudoRapidity
Cha
rged
Par
ticle
Den
sity
pyA pyDW pyDWT ATLAS
Charged Particles (all pT)
Generator Level14 TeV
Charged Particle Density: dN/dY
0
2
4
6
8
10
12
-10 -8 -6 -4 -2 0 2 4 6 8 10
Rapidity Y
Cha
rged
Par
ticle
Den
sity
pyA pyDW pyDWT ATLAS
Generator Level14 TeV
Charged Particles (all pT)
PYTHIA 6.2 TunesPYTHIA 6.2 TunesLHC Min-Bias PredictionsLHC Min-Bias Predictions
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 26
The ATLAS tune has many more “soft” particles than does any of the CDF Tunes. The ATLAS tune has <pT> = 548 MeV/c while Tune A has <pT> = 641 MeV/c (100 MeV/c more per particle)!
Shows the predictions of PYTHIA Tune A, Tune DW, Tune DWT, and the ATLAS tune for the charged particle pT distribution at 14 TeV (|| < 1) and the average number of charged particles with pT > pT
min (|| < 1).
Charged PT Distribution
0.1
1.0
10.0
100.0
0.0 0.5 1.0 1.5 2.0 2.5 3.0
Charged Particle PT (GeV/c)
1/N
ev d
N/d
PT (1
/GeV
/c)
pyA <PT> = 641 MeV/c
pyDW <PT> = 665 MeV/c
pyDWT <PT> = 693 MeV/c
ATLAS <PT> = 548 MeV/c
Charged Particles (||<1.0)
Generator LevelMin-Bias 14 TeV
Average Number of Charged Particles vs PTmin
0
5
10
15
20
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
Minimum PT (GeV/c)
<Nch
g>
pyA pyDW pyDWTATLAS
Charged Particles (||<1.0, PT>PTmin)
Generator LevelMin-Bias 14 TeV
PYTHIA 6.2 TunesPYTHIA 6.2 TunesLHC Min-Bias PredictionsLHC Min-Bias Predictions
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 27
Shows the average transverse momentum of charged particles (||<1, pT>0.5 GeV) versus the number of charged particles, Nchg, for the CDF Run 2 Min-Bias events.
The charged <PT> rises with Nchg!
Average PT versus Nchg
0.6
0.8
1.0
1.2
1.4
1.6
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28
Number of Charged Particles
Ave
rage
PT
(GeV
/c)
CDF Preliminarydata uncorrectedtheory + CDFSIM
PYTHIA Tune A 1.96 TeV
Charged Particles (||<1.0, PT>0.5 GeV/c)
Min-Bias
Charged <PCharged <PTT> versus N> versus Nchgchg
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 28
Using Pile-Up to Study Min-BiasUsing Pile-Up to Study Min-Bias
The primary vertex is the highest PTsum of charged particles pointing towards it.
Proton AntiProton
60 cm
Primary
Normally one only includes those charged particles which point back to the primary vertex.
Pile-Up
However, the primary vertex is presumably the collision that satisfied the trigger and is hence biased.
Perhaps the pile-up is not biases and can serve as a new type of “Min-Bias” trigger.
This assumes that the pile-up is not affected by the trigger (i.e. it is the same for all primary processes).
High PT Jet
Primary
MB
CDF Run 2
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 29
Using Pile-Up to Study Min-BiasUsing Pile-Up to Study Min-BiasCharged Particle Density: dN/d
0
1
2
3
4
-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0
PseudoRapidity
Cha
rged
Par
ticle
Den
sity
Charged Particles (PT > 0.5 GeV/c)
CDF Pre-PreliminaryMin-Bias at 1.96 TeVPrimary
Charged Particle Density: dN/d
0
1
2
3
4
-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0
PseudoRapidity
Cha
rged
Par
ticle
Den
sity
Charged Particles (PT > 0.5 GeV/c)
CDF Pre-PreliminaryMin-Bias at 1.96 TeV
Pile-Up
Primary
Shows the the charged particle density, dNchg/dfor charged particles (pT > 0.5 GeV/c) pointing to theprimary vertex for “Min-Bias” collisions at 1.96 TeV.
About 2.6 charged particles per unit at = 0.
About 1.6 charged particles per unit at = 0 per pile-up
interaction.
Shows the the charged particle density, dNchg/d(per interaction) for charged particles (pT > 0.5 GeV/c) pointing to thepile-up vertices for “Min-Bias” collisions at 1.96 TeV.
Clearly the pile-up “min-bias” is biased because there must to be some particles in the central region to form a vertex (e.g. elestic scattering does not contribute), but it is less biased than CDF “min-bias”.
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 30
Is the Pile-Up Biased?Is the Pile-Up Biased?Pile-Up: Charged Particle Multiplicity
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
0 5 10 15 20 25 30
Number of Charged Particles
Frac
tion
of E
vent
s
Min-Bias Events<Nchg> = 3.2
CDF Pre-Preliminary1.96 TeV
Charged Particles (PT > 0.5 GeV/c, || < 1)
Pile-Up: Charged Particle Multiplicity
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
0 5 10 15 20 25 30
Number of Charged Particles
Frac
tion
of E
vent
s
Min-Bias Events<Nchg> = 3.2
CDF Pre-Preliminary1.96 TeV
PT(jet#1) > 150 GeV/c<Nchg> = 4.2
Charged Particles (PT > 0.5 GeV/c, || < 1)
Shows the the charged particle multiplicity distribution(per interaction)for charged particles (pT > 0.5 GeV/c, || <1) pointing to thepile-up vertices for “Min-Bias” collisions at 1.96 TeV.
Shows the the charged particle multiplicity distribution (per interaction) for charged particles (pT > 0.5 GeV/c, || <1) pointing to thepile-up vertices for high p jet production (PT(jet#1) > 150 GeV/c) at 1.96 TeV.
The pile-up is different for Min-bias collisions and high pT jet production! Amasing!
Warning! This data is verypreliminary and
not “blessed” by CDF.So do not believe it yet!
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 31
Is the Pile-Up Biased?Is the Pile-Up Biased? Jet#1 Direction
Correlations in
Charged Particle Density: dN/dd
0.1
1.0
10.0
100.0
0 30 60 90 120 150 180 210 240 270 300 330 360 (degrees)
Cha
rged
Par
ticle
Den
sity
Charged Particles (PT > 0.5 GeV/c, || <1)
PrimaryCDF Preliminary1.96 TeV
150 < PT(jet#1) < 250 GeV/c
Shows the data on the dependence of the charged particle density, dNchg/dd, for charged particles (pT > 0.5 GeV/c, || < 1) pointing to theprimary vertex relative to the leading calorimeter jet (rotated to 270o) for 150 < PT(jet#1) < 250 GeV/c |(jet#1)| < 2.
Shows the data on the dependence of the charged particle density, dNchg/dd, for charged particles (pT > 0.5 GeV/c, || < 1) (per interaction) pointing to thepile-up vertices relative to the leading calorimeter jet (rotated to 270o) for 150 < PT(jet#1) < 250 GeV/c |(jet#1)| < 2.
Transverse Region
Charged Particle Density: dN/dd
0.1
1.0
10.0
100.0
0 30 60 90 120 150 180 210 240 270 300 330 360 (degrees)
Cha
rged
Par
ticle
Den
sity
Charged Particles (PT > 0.5 GeV/c, || <1)
Primary
Pile-Up/Interaction
CDF Preliminary1.96 TeV
150 < PT(jet#1) < 250 GeV/c
Charged PTsum Density: dPT/dd
0.1
1.0
10.0
100.0
1000.0
0 30 60 90 120 150 180 210 240 270 300 330 360 (degrees)
Cha
rged
PTs
um D
ensi
ty (G
eV/c
) CDF Preliminary1.96 TeV
150 < PT(jet#1) < 250 GeV/cPrimary
Pile-Up/Interaction
The pile-up knows the direction of the leading high pT jet! Amasing!
The pile-up conspires to help give you what you ask for
(i.e. satisfy your “trigger” or your event selection)!
Warning! This data is verypreliminary and
not “blessed” by CDF.So do not believe it yet!
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 32
Min-Bias SummaryMin-Bias Summary “Min-Bias” is not well defined. What you
see depends on what you trigger on! Every trigger produces some biases. We learn about “min-bias” by comparing different “low bias” triggers.
Proton AntiProton
“Minumum Bias” Collisions
Preliminary results seem to show that pile-up is biased! and that it conspires to help give you what you ask for (i.e. satisfy your “trigger” or your event selection)!
If true this means the pile-up is not the same for all processes. It is process (i.e. trigger) dependent! This would have big implications for the LHC!
Pile-Up Charged PTsum Density: dPT/dd
0.1
1.0
10.0
0 30 60 90 120 150 180 210 240 270 300 330 360 (degrees)
Cha
rged
PTs
um D
ensi
ty (G
eV/c
) Min-Bias35 < PT(jet#1) < 80 GeV/c150 < PT(jet#1) < 250 GeV/c
Charged Particles (PT > 0.5 GeV/c, || <1)
CDF Preliminary1.96 TeV
I must double check my analysis and get it “blessed”!
Leading Jet
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 33
QCD Monte-Carlo Models:QCD Monte-Carlo Models:High Transverse Momentum JetsHigh Transverse Momentum Jets
Start with the perturbative 2-to-2 (or sometimes 2-to-3) parton-parton scattering and add initial and final-state gluon radiation (in the leading log approximation or modified leading log approximation).
Hard Scattering
PT(hard)
Outgoing Parton
Outgoing Parton
Initial-State Radiation
Final-State Radiation
Hard Scattering
PT(hard)
Outgoing Parton
Outgoing Parton
Initial-State Radiation
Final-State Radiation
Proton AntiProton
Underlying Event Underlying Event
Proton AntiProton
Underlying Event Underlying Event
“Hard Scattering” Component
“Jet”
“Jet”
“Underlying Event”
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.
“Jet”
The “underlying event” is an unavoidable background to most collider observables and having good understand of it leads to
more precise collider measurements!
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 34
Charged Jet #1Direction
“Transverse” “Transverse”
“Toward”
“Away”
“Toward-Side” Jet
“Away-Side” Jet
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 - space, x = 2x120o = 4/3.
Charged Jet #1Direction
“Toward”
“Transverse” “Transverse”
“Away”
-1 +1
2
0
Leading Jet
Toward Region
Transverse Region
Transverse Region
Away Region
Away Region
Charged Particle Correlations PT > 0.5 GeV/c || < 1
Look at the charged particle density in the “transverse” region!“Transverse” region
very sensitive to the “underlying event”!
CDF Run 1 Analysis
CDF Run 1: Evolution of Charged JetsCDF Run 1: Evolution of Charged Jets“Underlying Event”“Underlying Event”
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 35
Compares the average “transverse” charge particle density with the average “Min-Bias” charge particle density (||<1, pT>0.5 GeV). Shows how the “transverse” charge particle density and the Min-Bias charge particle density is distributed in pT.
CDF Run 1 Min-Bias data<dNchg/dd> = 0.25
PT(charged jet#1) > 30 GeV/c“Transverse” <dNchg/dd> = 0.56
Factor of 2!
“Min-Bias”
"Transverse" Charged Particle Density: dN/dd
0.00
0.25
0.50
0.75
1.00
0 5 10 15 20 25 30 35 40 45 50
PT(charged jet#1) (GeV/c)
"Tra
nsve
rse"
Cha
rged
Den
sity
CDF Min-BiasCDF JET20
CDF Run 1data uncorrected
1.8 TeV ||<1.0 PT>0.5 GeV/c
Charged Particle Jet #1 Direction
“Toward”
“Transverse” “Transverse”
“Away”
Charged Particle Density
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
0 2 4 6 8 10 12 14
PT(charged) (GeV/c)C
harg
ed D
ensi
ty d
N/d
d
dPT
(1/G
eV/c
)
CDF Run 1data uncorrected
1.8 TeV ||<1 PT>0.5 GeV/c
Min-Bias
"Transverse"PT(chgjet#1) > 5 GeV/c
"Transverse"PT(chgjet#1) > 30 GeV/c
Run 1 Charged Particle DensityRun 1 Charged Particle Density “Transverse” p“Transverse” pTT Distribution Distribution
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 36
Plot shows average “transverse” charge particle density (||<1, pT>0.5 GeV) versus PT(charged jet#1) compared to the QCD hard scattering predictions of ISAJET 7.32 (default parameters with PT(hard)>3 GeV/c) .
The predictions of ISAJET are divided into two categories: charged particles that arise from the break-up of the beam and target (beam-beam remnants); and charged particles that arise from the outgoing jet plus initial and final-state radiation (hard scattering component).
Beam-BeamRemnants
ISAJETCharged Jet #1Direction
“Toward”
“Transverse” “Transverse”
“Away”
“Hard”Component
"Transverse" Charged Particle Density: dN/dd
0.00
0.25
0.50
0.75
1.00
0 5 10 15 20 25 30 35 40 45 50
PT(charged jet#1) (GeV/c)
"Tra
nsve
rse"
Cha
rged
Den
sity
CDF Run 1Datadata uncorrectedtheory corrected
1.8 TeV ||<1.0 PT>0.5 GeV
Isajet
"Remnants"
"Hard"
ISAJET 7.32ISAJET 7.32“Transverse” Density“Transverse” Density
ISAJET uses a naïve leading-log parton shower-model which does
not agree with the data!
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 37
Plot shows average “transverse” charge particle density (||<1, pT>0.5 GeV) versus PT(charged jet#1) compared to the QCD hard scattering predictions of HERWIG 5.9 (default parameters with PT(hard)>3 GeV/c).
The predictions of HERWIG are divided into two categories: charged particles that arise from the break-up of the beam and target (beam-beam remnants); and charged particles that arise from the outgoing jet plus initial and final-state radiation (hard scattering component).
Beam-BeamRemnants
HERWIG
Charged Jet #1Direction
“Toward”
“Transverse” “Transverse”
“Away”
"Transverse" Charged Particle Density: dN/dd
0.00
0.25
0.50
0.75
1.00
0 5 10 15 20 25 30 35 40 45 50
PT(charged jet#1) (GeV/c)
"Tra
nsve
rse"
Cha
rged
Den
sity
CDF Run 1Datadata uncorrectedtheory corrected
1.8 TeV ||<1.0 PT>0.5 GeV
Herwig 6.4 CTEQ5LPT(hard) > 3 GeV/c
Total "Hard"
"Remnants"
“Hard”Component
"Transverse" Charged Particle Density: dN/dd
0.00
0.25
0.50
0.75
1.00
0 5 10 15 20 25 30 35 40 45 50
PT(charged jet#1) (GeV/c)
"Tra
nsve
rse"
Cha
rged
Den
sity
CDF Run 1Datadata uncorrectedtheory corrected
1.8 TeV ||<1.0 PT>0.5 GeV
Isajet
"Remnants"
"Hard"
HERWIG uses a modified leading-log parton shower-model which
does agrees better with the data!
HERWIG 6.4HERWIG 6.4“Transverse” Density“Transverse” Density
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 38
"Transverse" Charged Particle Density
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
0 2 4 6 8 10 12 14
PT(charged) (GeV/c)C
harg
ed D
ensi
ty d
N/d
d
dPT
(1/G
eV/c
)
CDF Datadata uncorrectedtheory corrected
1.8 TeV ||<1 PT>0.5 GeV/c
PT(chgjet#1) > 5 GeV/c
PT(chgjet#1) > 30 GeV/c
Herwig 6.4 CTEQ5L
Herwig PT(chgjet#1) > 5 GeV/c<dNchg/dd> = 0.40
Herwig PT(chgjet#1) > 30 GeV/c“Transverse” <dNchg/dd> = 0.51
"Transverse" Charged Particle Density: dN/dd
0.00
0.25
0.50
0.75
1.00
0 5 10 15 20 25 30 35 40 45 50
PT(charged jet#1) (GeV/c)
"Tra
nsve
rse"
Cha
rged
Den
sity
CDF Datadata uncorrectedtheory corrected
1.8 TeV ||<1.0 PT>0.5 GeV
Herwig 6.4 CTEQ5LPT(hard) > 3 GeV/c
Total "Hard"
"Remnants"
Compares the average “transverse” charge particle density (||<1, pT>0.5 GeV) versus PT(charged jet#1) and the pT distribution of the “transverse” density, dNchg/dddPT with the QCD hard scattering predictions of HERWIG 6.4 (default parameters with PT(hard)>3 GeV/c. Shows how the “transverse” charge particle density is distributed in pT.
HERWIG has the too steep of a pT dependence of the “beam-beam remnant”
component of the “underlying event”! Charged Jet #1Direction
“Toward”
“Transverse” “Transverse”
“Away”
HERWIG 6.4HERWIG 6.4“Transverse” P“Transverse” PTT Distribution Distribution
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 39
MPI: Multiple PartonMPI: Multiple PartonInteractionsInteractions
PYTHIA models the “soft” component of the underlying event with color string fragmentation, but in addition includes a contribution arising from multiple parton interactions (MPI) in which one interaction is hard and the other is “semi-hard”.
Proton AntiProton
Multiple Parton Interaction
initial-state radiation
final-state radiation outgoing parton
outgoing parton
color string
color string
The probability that a hard scattering events also contains a semi-hard multiple parton interaction can be varied but adjusting the cut-off for the MPI.
One can also adjust whether the probability of a MPI depends on the PT of the hard scattering, PT(hard) (constant cross section or varying with impact parameter).
One can adjust the color connections and flavor of the MPI (singlet or nearest neighbor, q-qbar or glue-glue).
Also, one can adjust how the probability of a MPI depends on PT(hard) (single or double Gaussian matter distribution).
+
“Semi-Hard” MPI “Hard” Component
initial-state radiation
final-state radiation outgoing jet Beam-Beam Remnants
or
“Soft” Component
Proton AntiProton
“Hard” Collision
initial-state radiation
final-state radiation outgoing parton
outgoing parton
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 40
Parameter Default
Description
PARP(83) 0.5 Double-Gaussian: Fraction of total hadronic matter within PARP(84)
PARP(84) 0.2 Double-Gaussian: Fraction of the overall hadron radius containing the fraction PARP(83) of the total hadronic matter.
PARP(85) 0.33 Probability that the MPI produces two gluons with color connections to the “nearest neighbors.
PARP(86) 0.66 Probability that the MPI produces two gluons either as described by PARP(85) or as a closed gluon loop. The remaining fraction consists of quark-antiquark pairs.
PARP(89) 1 TeV Determines the reference energy E0.
PARP(90) 0.16 Determines the energy dependence of the cut-offPT0 as follows PT0(Ecm) = PT0(Ecm/E0) with = PARP(90)
PARP(67) 1.0 A scale factor that determines the maximum parton virtuality for space-like showers. The larger the value of PARP(67) the more initial-state radiation.
Hard Core
Multiple Parton Interaction
Color String
Color String
Multiple Parton Interaction
Color String
Hard-Scattering Cut-Off PT0
1
2
3
4
5
100 1,000 10,000 100,000CM Energy W (GeV)
PT0
(GeV
/c)
PYTHIA 6.206
= 0.16 (default)
= 0.25 (Set A))
Take E0 = 1.8 TeV
Reference pointat 1.8 TeV
Determine by comparingwith 630 GeV data!
Affects the amount ofinitial-state radiation!
Tuning PYTHIA:Tuning PYTHIA:Multiple Parton Interaction ParametersMultiple Parton Interaction Parameters
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 41
"Transverse" Charged Particle Density: dN/dd
0.00
0.25
0.50
0.75
1.00
0 5 10 15 20 25 30 35 40 45 50
PT(charged jet#1) (GeV/c)"T
rans
vers
e" C
harg
ed D
ensi
ty
CTEQ3L CTEQ4L CTEQ5L CDF Min-Bias CDF JET20
1.8 TeV ||<1.0 PT>0.5 GeV
Pythia 6.206 (default)MSTP(82)=1
PARP(81) = 1.9 GeV/c
CDF Datadata uncorrectedtheory corrected
Default parameters give very poor description of the “underlying event”!
Note ChangePARP(67) = 4.0 (< 6.138)PARP(67) = 1.0 (> 6.138)
Parameter 6.115 6.125 6.158 6.206
MSTP(81) 1 1 1 1
MSTP(82) 1 1 1 1
PARP(81) 1.4 1.9 1.9 1.9
PARP(82) 1.55 2.1 2.1 1.9
PARP(89) 1,000 1,000 1,000
PARP(90) 0.16 0.16 0.16
PARP(67) 4.0 4.0 1.0 1.0
Plot shows the “Transverse” charged particle density versus PT(chgjet#1) compared to the QCD hard scattering predictions of PYTHIA 6.206 (PT(hard) > 0) using the default parameters for multiple parton interactions and CTEQ3L, CTEQ4L, and CTEQ5L.
PYTHIA default parameters
PYTHIA 6.206 DefaultsPYTHIA 6.206 DefaultsMPI constant
probabilityscattering
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 42
Old PYTHIA default(more initial-state radiation)New PYTHIA default
(less initial-state radiation)
Parameter 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
Old PYTHIA default(more initial-state radiation)New PYTHIA default
(less initial-state radiation)
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)).
"Transverse" Charged Particle Density: dN/dd
0.00
0.25
0.50
0.75
1.00
0 5 10 15 20 25 30 35 40 45 50
PT(charged jet#1) (GeV/c)
"Tra
nsve
rse"
Cha
rged
Den
sity
1.8 TeV ||<1.0 PT>0.5 GeV
CDF Preliminarydata uncorrectedtheory corrected
CTEQ5L
PYTHIA 6.206 (Set A)PARP(67)=4
PYTHIA 6.206 (Set B)PARP(67)=1
Run 1 Analysis
Run 1 PYTHIA Tune ARun 1 PYTHIA Tune APYTHIA 6.206 CTEQ5L
CDF Default!
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 43
Charged Particle Jet #1 Direction
“Toward”
“Transverse” “Transverse”
“Away”
"Transverse" Charged Particle Density: dN/dd
0.00
0.25
0.50
0.75
1.00
1.25
0 5 10 15 20 25 30 35 40 45 50
PT(charged jet#1) (GeV/c)"T
rans
vers
e" C
harg
ed D
ensi
ty
CDF Run 1 Min-BiasCDF Run 1 JET20
CDF Run 1 Datadata uncorrected
1.8 TeV ||<1.0 PT>0.5 GeV
"Transverse" Charged Particle Density: dN/dd
0.00
0.25
0.50
0.75
1.00
1.25
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
PT(charged jet#1) (GeV/c)"T
rans
vers
e" C
harg
ed D
ensi
ty
CDF Run 1 Min-BiasCDF Run 1 JET20
||<1.0 PT>0.5 GeV
CDF Preliminarydata uncorrected
Shows the data on the average “transverse” charge particle density (||<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 correlated systematic uncertainties.
"Transverse" Charged Particle Density: dN/dd
0.00
0.25
0.50
0.75
1.00
1.25
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
PT(charged jet#1) (GeV/c)
"Tra
nsve
rse"
Cha
rged
Den
sity
CDF Run 2
"Transverse" Charged Particle Density: dN/dd
0.00
0.25
0.50
0.75
1.00
1.25
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
PT(charged jet#1) (GeV/c)
"Tra
nsve
rse"
Cha
rged
Den
sity CDF Run 1 Published
CDF Run 2 Preliminary
||<1.0 PT>0.5 GeV/c
CDF Preliminarydata uncorrected
Excellent agreement between Run 1 and 2!
"Transverse" Charged Particle Density: dN/dd
0.00
0.25
0.50
0.75
1.00
1.25
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
PT(charged jet#1) (GeV/c)
"Tra
nsve
rse"
Cha
rged
Den
sity
CDF Run 1 PublishedCDF Run 2 PreliminaryPYTHIA Tune A
||<1.0 PT>0.5 GeV/c
CDF Preliminarydata uncorrectedtheory corrected
PYTHIA Tune A was tuned to fit the “underlying event” in Run I!
Shows the prediction of PYTHIA Tune A at 1.96 TeV after detector simulation (i.e. after CDFSIM).
Run 1 vs Run 2: “Transverse” Run 1 vs Run 2: “Transverse” Charged Particle DensityCharged Particle Density“Transverse” region as defined by the leading “charged particle jet”
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 44
Shows the data on the average “transverse” charged PTsum density (||<1, pT>0.5 GeV) as a function of the transverse momentum of the leading charged particle jet from Run 1.
"Transverse" Charged PTsum Density: dPTsum/dd
0.00
0.25
0.50
0.75
1.00
1.25
0 5 10 15 20 25 30 35 40 45 50
PT(charged jet#1) (GeV/c)"T
rans
vers
e" P
Tsum
Den
sity
(GeV
) CDF JET20CDF Min-Bias
CDF Run 1 Datadata uncorrected
1.8 TeV ||<1.0 PT>0.5 GeV
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 correlated systematic uncertainties.
"Transverse" Charged PTsum Density: dPTsum/dd
0.00
0.25
0.50
0.75
1.00
1.25
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
PT(charged jet#1) (GeV/c)"T
rans
vers
e" P
Tsum
Den
sity
(GeV
)
CDF JET20CDF Min-Bias
CDF Preliminarydata uncorrected
||<1.0 PT>0.5 GeV
Charged Particle Jet #1 Direction
“Toward”
“Transverse” “Transverse”
“Away”
"Transverse" Charged PTsum Density: dPTsum/dd
0.00
0.25
0.50
0.75
1.00
1.25
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
PT(charged jet#1) (GeV/c)"T
rans
vers
e" P
Tsum
Den
sity
(GeV
)
CDF Run 2
"Transverse" Charged PTsum Density: dPTsum/dd
0.00
0.25
0.50
0.75
1.00
1.25
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
PT(charged jet#1) (GeV/c)"T
rans
vers
e" P
Tsum
Den
sity
(GeV
/c)
CDF Run 1 PublishedCDF Run 2 Preliminary
CDF Preliminarydata uncorrected
||<1.0 PT>0.5 GeV/c
Excellent agreement between Run 1 and 2!
"Transverse" Charged PTsum Density: dPTsum/dd
0.00
0.25
0.50
0.75
1.00
1.25
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
PT(charged jet#1) (GeV/c)"T
rans
vers
e" P
Tsum
Den
sity
(GeV
/c)
CDF Run 1 PublishedCDF Run 2 PreliminaryPYTHIA Tune A
CDF Preliminarydata uncorrectedtheory corrected
||<1.0 PT>0.5 GeV/c
Shows the prediction of PYTHIA Tune A at 1.96 TeV after detector simulation (i.e. after CDFSIM).
PYTHIA Tune A was tuned to fit the “underlying event” in Run I!
Run 1 vs Run 2: “Transverse” Run 1 vs Run 2: “Transverse” Charged PTsum DensityCharged PTsum Density
“Transverse” region as defined by the leading “charged particle jet”
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 45
Compares the average “transverse” charge particle density (||<1, pT>0.5 GeV) versus PT(charged jet#1) with the pT distribution of the “transverse” density, dNchg/dddPT. Shows how the “transverse” charge particle density is distributed in pT.
Compares the Run 2 data (Min-Bias, JET20, JET50, JET70, JET100) with Run 1.
Charged Particle Density
1.0E-07
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
0 2 4 6 8 10 12 14 16 18 20
PT(charged) (GeV/c)
Cha
rged
Den
sity
dN
/d
ddP
T (1
/GeV
/c)
CDF Run 1data uncorrected
Charged Particles || < 1.0
Min-Bias
"Transverse"PT(chgjet#1) > 30 GeV/c
"Transverse" Charged Particle Density: dN/dd
0.00
0.25
0.50
0.75
1.00
1.25
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
PT(charged jet#1) (GeV/c)
"Tra
nsve
rse"
Cha
rged
Den
sity
CDF Run 1 Min-BiasCDF Run 1 JET20
||<1.0 PT>0.5 GeV
CDF Preliminarydata uncorrected
"Transverse" Charged Particle Density: dN/dd
0.00
0.25
0.50
0.75
1.00
1.25
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
PT(charged jet#1) (GeV/c)
"Tra
nsve
rse"
Cha
rged
Den
sity
CDF Run 2
Charged Particle Density
1.0E-07
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
0 2 4 6 8 10 12 14 16 18 20
PT(charged) (GeV/c)
Cha
rged
Den
sity
dN
/d
ddP
T (1
/GeV
/c)
CDF Preliminarydata uncorrected
Charged Particles || < 1.0
"Transverse" Charged Particle Density: dN/dd
0.00
0.25
0.50
0.75
1.00
1.25
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
PT(charged jet#1) (GeV/c)
"Tra
nsve
rse"
Cha
rged
Den
sity CDF Run 1 Published
CDF Run 2 Preliminary
||<1.0 PT>0.5 GeV/c
CDF Preliminarydata uncorrected
Charged Particle Density
1.0E-07
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
0 2 4 6 8 10 12 14 16 18 20
PT(charged) (GeV/c)
Cha
rged
Den
sity
dN
/d
ddP
T (1
/GeV
/c) Run 2 Min-Bias Preliminary
Run 1 Min-Bias PreliminaryRun 2 PreliminaryRun 1 Published
CDF Preliminarydata uncorrected
Charged Particles || < 1.0
Min-Bias
"Transverse"PT(chgjet#1) > 30 GeV/c
Excellent agreement between Run 1 and 2!
Charged Particle DensityCharged Particle Density “Transverse” p “Transverse” pTT Distribution Distribution
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 46
JetClu Jet #1 Direction
“Transverse” “Transverse”
“Toward”
“Away”
“Toward-Side” Jet
“Away-Side” Jet
Look at charged particle correlations in the azimuthal angle relative to the leading JetClu jet.
Define || < 60o as “Toward”, 60o < || < 120o as “Transverse”, and || > 120o as “Away”. All three regions have the same size in - space, x = 2x120o = 4/3.
Charged Particle Correlations pT > 0.5 GeV/c || < 1
Away-side “jet”(sometimes)
Perpendicular to the plane of the 2-to-2 hard scattering
“Transverse” region is very sensitive to the “underlying event”!
JetClu 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 in the “transverse” region!
““Underlying Event”Underlying Event”as defined by “Calorimeter Jets”as defined by “Calorimeter Jets”
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 47
Shows the data on the average “transverse” charge particle density (||<1, PT>0.5 GeV) as a function of the transverse energy of the leading JetClu jet (R = 0.7, |(jet)| < 2) from Run 2.
JetClu Jet #1 Direction
“Toward”
“Transverse” “Transverse”
“Away”
Compares the “transverse” region of the leading “charged particle jet”, chgjet#1, with the “transverse” region of the leading “calorimeter jet” (JetClu R = 0.7), jet#1.
JetClu Jet #1 or ChgJet#1
Direction
“Toward”
“Transverse” “Transverse”
“Away”
, compared with PYTHIA Tune A after CDFSIM.
"Transverse" Charged Particle Density: dN/dd
0.00
0.25
0.50
0.75
1.00
0 25 50 75 100 125 150 175 200 225 250
ET(jet#1) (GeV)
"Tra
nsve
rse"
Cha
rged
Den
sity
CDF Preliminarydata uncorrected
Charged Particles (||<1.0, PT>0.5 GeV/c)
JetClu (R = 0.7, |(jet#1)| < 2)
“Transverse” region as defined by the leading
“calorimeter jet” "Transverse" Charged Particle Density: dN/dd
0.00
0.25
0.50
0.75
1.00
0 25 50 75 100 125 150 175 200 225 250
ET(jet#1) (GeV)
"Tra
nsve
rse"
Cha
rged
Den
sity
PYTHIA Tune ACDF Run 2 Preliminary
CDF Preliminarydata uncorrectedtheory corrected
Charged Particles (||<1.0, PT>0.5 GeV/c)
JetClu (R = 0.7, |(jet#1)| < 2)
"Transverse" Charged Particle Density: dN/dd
0.00
0.25
0.50
0.75
1.00
0 25 50 75 100 125 150 175 200 225 250
PT(chgjet#1) or ET(jet#1) (GeV)
"Tra
nsve
rse"
Cha
rged
Den
sity CDF Preliminary
data uncorrected
Charged Particles (||<1.0, PT>0.5 GeV/c)
ChgJet#1 R = 0.7
JetClu Jet#1 (R = 0.7,|(jet)|<2)
"Transverse" Charged Particle Density: dN/dd
0.00
0.25
0.50
0.75
1.00
0 25 50 75 100 125 150 175 200 225 250
PT(chgjet#1) or ET(jet#1) (GeV)
"Tra
nsve
rse"
Cha
rged
Den
sity
CDF Preliminarydata uncorrectedtheory corrected
Charged Particles (||<1.0, PT>0.5 GeV/c)
ChgJet#1 R = 0.7
JetClu Jet#1 (R = 0.7, |(jet)|<2)
PYTHIA Tune A 1.96 TeV
““Transverse” Transverse” Charged Particle DensityCharged Particle Density
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 48
Shows the data on the average “transverse” charged PTsum density (||<1, PT>0.5 GeV) as a function of the transverse energy of the leading JetClu jet (R = 0.7, |(jet)| < 2) from Run 2.
JetClu Jet #1 Direction
“Toward”
“Transverse” “Transverse”
“Away”
Compares the “transverse” region of the leading “charged particle jet”, chgjet#1, with the “transverse” region of the leading “calorimeter jet” (JetClu R = 0.7), jet#1.
JetClu Jet #1 or ChgJet#1
Direction
“Toward”
“Transverse” “Transverse”
“Away”
, compared with PYTHIA Tune A after CDFSIM.
"Transverse" Charged PTsum Density: dPTsum/dd
0.0
0.5
1.0
1.5
0 25 50 75 100 125 150 175 200 225 250
ET(jet#1) (GeV)
"Tra
nsve
rse"
PTs
um D
ensi
ty (G
eV/c
)
CDF Preliminarydata uncorrected
Charged Particles (||<1.0, PT>0.5 GeV/c)
JetClu (R = 0.7, |(jet#1)| < 2)
“Transverse” region as defined by the leading
“calorimeter jet” "Transverse" Charged PTsum Density: dPTsum/dd
0.0
0.5
1.0
1.5
0 25 50 75 100 125 150 175 200 225 250
ET(jet#1) (GeV)
"Tra
nsve
rse"
PTs
um D
ensi
ty (G
eV/c
)
PYTHIA Tune ACDF Run 2 Preliminary
CDF Preliminarydata uncorrectedtheory corrected
Charged Particles (||<1.0, PT>0.5 GeV/c)
JetClu (R = 0.7, |(jet#1)| < 2)
"Transverse" Charged PTsum Density: dPTsum/dd
0.0
0.5
1.0
1.5
0 25 50 75 100 125 150 175 200 225 250
PT(chgjet#1) or ET(jet#1) (GeV)
"Tra
nsve
rse"
PTs
um D
ensi
ty (G
eV/c
)
CDF Preliminarydata uncorrected
Charged Particles (||<1.0, PT>0.5 GeV/c) ChgJet#1 R = 0.7
JetClu Jet#1 (R = 0.7,|(jet)|<2)
"Transverse" Charged PTsum Density: dPTsum/dd
0.0
0.5
1.0
1.5
0 25 50 75 100 125 150 175 200 225 250
PT(chgjet#1) or ET(jet#1) (GeV)
"Tra
nsve
rse"
PTs
um D
ensi
ty (G
eV/c
) CDF Preliminarydata uncorrectedtheory corrected
Charged Particles (||<1.0, PT>0.5 GeV/c) ChgJet#1 R = 0.7
JetClu Jet#1 (R = 0.7,|(jet)|<2)
PYTHIA Tune A 1.96 TeV
““Transverse” Transverse” Charged PTsum DensityCharged PTsum Density
MCnet07 - Durham - Part 1 April 18-20, 2007
Rick Field – Florida/CDF/CMS Page 49
Shows the ratio of PT(chgjet#1) to the “matched” JetClu jet ET versus PT(chgjet#1).
Shows the “matched” JetClu jet ET versus the transverse momentum of the leading “charged particle jet” (closest jet within R = 0.7 of the leading chgjet).
ET(matched jet) vs PT(charged jet#1)
0
20
40
60
80
100
120
140
160
180
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
PT(charged jet#1) (GeV/c)
Mat
ched
Jet
ET
(GeV
)
PYTHIA Tune ACDF Run 2 Preliminary
CDF Preliminarydata uncorrectedtheory corrected
Charged Particles (||<1.0, PT>0.5 GeV/c)
JetClu (R = 0.7, |(jet#1)| < 2)
PT(chgjet#1)/ET(matched jet) vs PT(chgjet#1)
0.2
0.4
0.6
0.8
1.0
1.2
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
PT(charged jet#1) (GeV/c)
PT(c
hgje
t#1)
/ET(
mat
ched
jet)
PYTHIA Tune ACDF Run 2 Preliminary
CDF Preliminarydata uncorrectedtheory corrected Charged Particles (||<1.0, PT>0.5 GeV/c)
JetClu (R = 0.7, |(jet#1)| < 2)
The leading chgjet comes from a JetClu jet that is, on the average,
about 90% charged!
In lecture 2 I will show youA more detailed study of the
“underlying event” inRun 2 at CDF!
Relationship BetweenRelationship Between“Calorimeter” and “Charged Particle” Jets“Calorimeter” and “Charged Particle” Jets