Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 1
Toward an Understanding ofToward an Understanding ofthe Overall Event Structurethe Overall Event Structure
of Hard Collisionsof Hard Collisions
The Past: Feynman-Field Fenomenology (1973-1980).
The Present: Studying the “Underlying Event” at CDF.
Outline of Talk
7 GeV 0’sto
400 GeV “jets”
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 2
CDF ColliderCDF ColliderPhenomenologyPhenomenology
I am a theorist working in the CDF experimental collaboration.
Proton
AntiProton
1 mile CDF
Proton AntiProton 2 TeV
I work on collider phenomenology related to CDF.
Only by working in the experimental collaboration am I able to have access to data and do the kind of phenomenology I enjoy (i.e. the kind of phenomenology I did with Feynman many years ago).
Theorist!
In addition to being an exceptional theoretical physicist (and very good at math!), Feynman was
a great phenomenologist and he enjoyed very much talking with experimenters.
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 3
“Feynman-Field Jet Model”
Feynman-FieldFeynman-FieldFenomenologyFenomenology
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).
1973-1980
FW1: “A QCD Model for e+e- Annihilation”, R. D. Field and S. Wolfram, Nucl. Phys. B213, 65-84 (1983).
My 1st graduate student!
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 4
“Feynman-Field Jet Model”
Feynman-FieldFeynman-FieldFenomenologyFenomenology
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).
1973-1980
FW1: “A QCD Model for e+e- Annihilation”, R. D. Field and S. Wolfram, Nucl. Phys. B213, 65-84 (1983).
My 1st graduate student!
Many people have contributed to our understanding
of hadron-hadron collisions!I will say a few words about
Feynman’s influence on the field.
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 5
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
high PT meson
Parton-Parton Scattering
Outgoing Parton
Outgoing Parton
FF1 1977 (preQCD)
“Black-Box Model”
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 6
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”
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 7
Quark-QuarkQuark-QuarkBlack-Box ModelBlack-Box 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 Festival August 23, 2002
Rick Field - Florida/CDF Page 8
Quark-QuarkQuark-QuarkBlack-Box ModelBlack-Box 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.”
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 9
Quark-QuarkQuark-QuarkBlack-Box ModelBlack-Box Model
FF1 1977 (preQCD)Predict
particle ratios
Predictincrease with increasing
CM energy W
Predictoverall event topology
(FFF1 paper 1977)
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 10
Telagram from FeynmanTelagram from Feynman
July 1976
SAW CRONIN AM NOW CONVINCED WERE RIGHT TRACK QUICK WRITEFEYNMAN
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 11
Letter from FeynmanLetter from FeynmanJuly 1976
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 12
Letter from Feynman:Letter from Feynman:page 1page 1
Spelling?
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 13
Letter from Feynman:Letter from Feynman:page 3page 3
It is fun!
Onward!
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 14
Napkin from FeynmanNapkin from Feynman
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 15
QCD ApproachQCD ApproachQuarks & GluonsQuarks & 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 Festival August 23, 2002
Rick Field - Florida/CDF Page 16
QCD ApproachQCD ApproachQuarks & GluonsQuarks & 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.”
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 17
QCD ApproachQCD ApproachQuarks & GluonsQuarks & Gluons
FFF2 1978
30 GeV!
Predictlarge “jet”
cross-section
Feynman quote from FFF2:“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.”
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 18
CDF Run II DiJet EventCDF Run II DiJet EventJuly 2002July 2002
ETjet1 = 403 GeV
ETjet2 = 322 GeV
Raw ET values!!
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 19
Monte-Carlo SimulationMonte-Carlo Simulationof Hadron-Hadron Collisionsof Hadron-Hadron Collisions
Color singlet proton collides with a color singlet antiproton.
Proton AntiProton
Proton AntiProton
color string
color string
Beam Remnants
Beam Remnants
color string
color string
Beam Remnants
Beam Remnants
quark-antiquark pairs
quark-antiquark pairs
Beam Remnants
Beam Remnants
Beam Remnants
Beam Remnants
Jet
Jet
A red quark gets knocked out of the proton and a blue antiquark gets knocked out of the antiproton.
At short times (small distances) the color forces are weak and the outgoing partons move away from the beam-beam remnants.
At long times (large distances) the color forces become strong and quark-antiquark pairs are pulled out of the vacuum and hadrons are formed.
The resulting event consists of hadrons and leptons in the form of two large transverse momentum outgoing jets plus the beam-beam remnants.
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 20
Monte-Carlo SimulationMonte-Carlo Simulationof Hadron-Hadron Collisionsof Hadron-Hadron Collisions
FF1-FFF1 (1977) “Black-Box” Model
F1-FFF2 (1978) QCD Approach
FF2 (1978) Monte-Carlo
simulation of “jets”
FFFW “FieldJet” (1980) QCD “leading-log order” simulation
of hadron-hadron collisions
ISAJET(“FF” Fragmentation)
HERWIG(“FW” Fragmentation)
PYTHIAtoday
“FF” or “FW” Fragmentation
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 21
Monte-Carlo SimulationMonte-Carlo Simulationof Hadron-Hadron Collisionsof Hadron-Hadron Collisions
FF1-FFF1 (1977) “Black-Box” Model
F1-FFF2 (1978) QCD Approach
FF2 (1978) Monte-Carlo
simulation of “jets”
FFFW “FieldJet” (1980) QCD “leading-log order” simulation
of hadron-hadron collisions
ISAJET(“FF” Fragmentation)
HERWIG(“FW” Fragmentation)
PYTHIAtoday
“FF” or “FW” Fragmentation
Feynman quote from FF2:“The predictions of the model are reasonable
enough physically that we expect it may be close enough to reality to be useful in
designing future experiments and to serve as a reasonable approximation to compare
to data. We do not think of the model as a sound physical theory, ....”
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 22
The “Underlying Event” inThe “Underlying Event” inHard Scattering ProcessesHard Scattering Processes
What happens when a proton and an antiproton collide with a center-of-mass energy of 2 TeV?
Proton AntiProton
“Soft” Collision (no hard scattering)
Proton AntiProton
“Hard” Scattering
PT(hard)
Outgoing Parton
Outgoing Parton
Underlying Event Underlying Event
Initial-State Radiation
Final-State Radiation
Proton AntiProton 2 TeV
Most of the time the proton and antiproton 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 “hard” parton-parton collision resulting in large transverse momentum outgoing partons.
Proton AntiProton
“Underlying Event”
Beam-Beam Remnants Beam-Beam Remnants
Initial-State Radiation
The “underlying event” is everything except the two outgoing hard scattered “jets”. It is an unavoidable background to many collider observables.
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 23
Min-Bias?
Beam-Beam RemnantsBeam-Beam Remnants
The underlying event in a hard scattering process has a “hard” component (particles that arise from initial & final-state radiation and from the outgoing hard scattered partons) and a “soft” component (beam-beam remnants).
However the “soft” component is color connected to the “hard” component so this separation is (at best) an approximation.
Proton AntiProton
“Hard” Collision
initial-state radiation
final-state radiation outgoing parton
outgoing parton
color string
color string
+
“Soft” Component “Hard” Component
initial-state radiation
final-state radiation outgoing jet
Beam-Beam Remnants
For ISAJET (no color flow) the “soft” and “hard” components are completely independent and the model for the beam-beam remnant component is the same as for min-bias (“cut pomeron”) but with a larger <PT>.
HERWIG breaks the color connection with a soft q-qbar pair and then models the beam-beam remnant component the same as HERWIG min-bias (cluster decay).
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 24
Studying the “Underlying Event”Studying the “Underlying Event”
at CDFat CDF
The underlying event in a hard scattering process is a complicated and not very well understood object. It is an interesting region since it probes the interface between perturbative and non-perturbative physics.
There are two CDF analyses which quantitatively study the underlying event and compare with the QCD Monte-Carlo models.
It is important to model this region well since it is an unavoidable background to all collider observables. Also, we need a good model of min-bias (zero-bias) collisions.
The Underlying Event:beam-beam remnantsinitial-state radiation
multiple-parton interactions
Proton AntiProton
PT(hard)
Outgoing Parton
Outgoing Parton
Underlying Event Underlying Event
Initial-State Radiation
Final-State Radiation
CDFCone AnalysisValeria TanoEve KovacsJoey Huston
Anwar Bhatti
CDFEvolution of Charged Jets
Rick FieldDavid Stuart
Rich Haas
Ph.D. Thesis PRD65:092002, 2002
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 25
Evolution of Charged JetsEvolution of Charged Jets“Underlying Event”“Underlying Event”
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
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 26
Charged Multiplicity Charged Multiplicity versus Pversus PTT(chgjet#1)(chgjet#1)
Data on the average number of “toward” (||<60o), “transverse” (60<||<120o), and “away” (||>120o) charged particles (PT > 0.5 GeV, || < 1, including jet#1) as a function of the transverse momentum of the leading charged particle jet. Each point corresponds to the <Nchg> in a 1 GeV bin. The solid (open) points are the Min-Bias (JET20) data. The errors on the (uncorrected) data include both statistical and correlated systematic uncertainties.
Charged Jet #1Direction
“Toward”
“Transverse” “Transverse”
“Away”
Underlying Event“plateau”
Nchg versus PT(charged jet#1)
0
2
4
6
8
10
12
0 5 10 15 20 25 30 35 40 45 50
PT(charged jet#1) (GeV/c)
<N
ch
g>
in
1 G
eV
/c b
in
1.8 TeV ||<1.0 PT>0.5 GeV
"Toward"
"Away"
"Transverse"
CDF Preliminarydata uncorrected
Factor of 2 more active than an average Min-Bias event!
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 27
ISAJET: ISAJET: “Transverse” Nchg “Transverse” Nchg versus Pversus PTT(chgjet#1)(chgjet#1)
Plot shows the “transverse” <Nchg> vs PT(chgjet#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 #1
Direction
“Toward”
“Transverse” “Transverse”
“Away”
"Transverse" Nchg versus PT(charged jet#1)
0
1
2
3
4
0 5 10 15 20 25 30 35 40 45 50
PT(charged jet#1) (GeV/c)
"Tra
ns
ve
rse
" <
Nc
hg
> i
n 1
Ge
V/c
bin
1.8 TeV ||<1.0 PT>0.5 GeV
CDF Preliminarydata uncorrectedtheory corrected
Beam-Beam Remnants
Isajet Total
Hard Component
Outgoing Jetsplus
Initial & Final-StateRadiation
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 28
HERWIG: “Transverse” Nchg HERWIG: “Transverse” Nchg versus Pversus PTT(chgjet#1)(chgjet#1)
Plot shows the “transverse” <Nchg> vs PT(chgjet#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
Outgoing Jetsplus
Initial & Final-StateRadiation
HERWIG
Charged Jet #1Direction
“Toward”
“Transverse” “Transverse”
“Away”
"Transverse" Nchg versus PT(charged jet#1)
0
1
2
3
4
0 5 10 15 20 25 30 35 40 45 50
PT (charged jet#1) (GeV/c)
"Tra
ns
ve
rse
" <
Nc
hg
> i
n 1
Ge
V/c
bin
1.8 TeV ||<1.0 PT>0.5 GeV Beam-Beam Remnants
Hard Component
CDF Preliminarydata uncorrectedtheory corrected
Herwig Total
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 29
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
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 30
PYTHIA: Multiple PartonPYTHIA: Multiple PartonInteractionsInteractions
Pythia uses multiple partoninteractions to enhacethe underlying event.
Proton AntiProton
Multiple Parton Interactions
PT(hard)
Outgoing Parton
Outgoing Parton
Underlying EventUnderlying Event
Parameter Value
Description
MSTP(81) 0 Multiple-Parton Scattering off
1 Multiple-Parton Scattering on
MSTP(82) 1 Multiple interactions assuming the same probability, with an abrupt cut-off PTmin=PARP(81)
3 Multiple interactions assuming a varying impact parameter and a hadronic matter overlap consistent with a single Gaussian matter distribution, with a smooth turn-off PT0=PARP(82)
4 Multiple interactions assuming a varying impact parameter and a hadronic matter overlap consistent with a double Gaussian matter distribution (governed by PARP(83) and PARP(84)), with a smooth turn-off PT0=PARP(82)
Hard Core
Multiple parton interaction more likely in a hard
(central) collision!
and now HERWIG
!
Herwig MPIJ. M. Butterworth
J. R. ForshawM. H. Seymour
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 31
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
PYTHIA 6.206 DefaultsPYTHIA 6.206 Defaults
PYTHIA default parameters
ConstantProbabilityScattering
"Transverse" Nchg versus PT(charged jet#1)
0
1
2
3
4
5
0 5 10 15 20 25 30 35 40 45 50
PT(charged jet#1) (GeV/c)"T
ran
sver
se"
<N
chg
>
CTEQ3L CTEQ4L CTEQ5L CDF Min-Bias CDF JET20
CDFdata uncorrectedtheory corrected
1.8 TeV ||<1.0 PT>0.5 GeV/c
Pythia 6.206 (default)MSTP(82)=1
PARP(81) = 1.9 GeV/c
Default parameters give very poor description of the “underlying event”!
Plot shows “Transverse” <Nchg> 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.
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 32
Parameter Tune 1 Tune 2
MSTP(81) 1 1
MSTP(82) 3 3
PARP(82) 1.6 GeV 1.7 GeV
PARP(85) 1.0 1.0
PARP(86) 1.0 1.0
PARP(89) 1.8 TeV 1.8 TeV
PARP(90) 0.16 0.16
PARP(67) 1.0 4.0
Old PYTHIA default(less initial-state radiation)
New PYTHIA default(less initial-state radiation)
Tuned PYTHIA 6.206Tuned PYTHIA 6.206
"Transverse" Nchg versus PT(charged jet#1)
0
1
2
3
4
0 5 10 15 20 25 30 35 40 45 50
PT(charged jet#1) (GeV/c)
"Tra
nsv
erse
" <
Nch
g>
in
1 G
eV/c
bin CDF
data uncorrectedtheory corrected
1.8 TeV ||<1.0 PT>0.5 GeV CTEQ5L
Tuned PYTHIA 6.206PARP(67)=1
Tuned PYTHIA 6.206PARP(67)=4
Can we distinguish between PARP(67)=1 and PARP(67)=4?
Plot shows “Transverse” <Nchg> versus PT(chgjet#1) compared to the QCD hard scattering predictions of two tuned versions of PYTHIA 6.206 (CTEQ5L, PARP(67)=1 and PARP(67)=4).
PYTHIA 6.206 CTEQ5L
Old PYTHIA default(less initial-state radiation)
New PYTHIA default(less initial-state radiation)
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 33
Collider PhenomenologyCollider PhenomenologyFrom 7 GeV/c From 7 GeV/c oo’s to 400 GeV “Jets”’s to 400 GeV “Jets”
FF1 (1977) 7 GeV/c 0’s
NLO QCD (2002)400 GeV “jets”
Feynman Festival August 23, 2002
Rick Field - Florida/CDF Page 34
Collider PhenomenologyCollider PhenomenologyFrom 7 GeV/c From 7 GeV/c oo’s to 400 GeV “Jets”’s to 400 GeV “Jets”
FF1 (1977) 7 GeV/c 0’s
NLO QCD (2002)400 GeV “jets”
Rick Field (Feynman Festival):“At the time of this writing,
there is still no sharp quantitative test of QCD.
We believe it is the correcttheory of strong interactions
because it qualitatively describes an enormous variety and amount of data over many decades of Q2.”
Feynman played an enormous role in our understanding of hadron-hadron collisions
and his influence is still being felt!
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