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Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 1
Rick FieldUniversity of Florida
Outline of Talk
Toward an Understanding ofToward an Understanding ofHadronHadron--HadronHadron CollisionsCollisions
From 7 GeV/c pions to 1 TeV jets!
Proton AntiProton
PT(hard)
Outgoing Parton
Outgoing Parton
Underlying EventUnderlying Event
Initial-State Radiation
Final-State Radiation
Mapping out the energy dependence of the UE: Tevatron to the LHC.
Early LHC UE predictions.
The early days of Feynman-Field Phenomenology.
The Berkeley Years – Rick & Jimmie.
From Feynman-Field to the LHC
Ricky & Sally.
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 2
Margaret Margaret MorlanMorlan
My mother was born on May 10, 1922, in Houston Texas. She died on Sunday November 6, 2011 in Malibu, California at age 89.
Margaret Field in “The Man From Planet X” (1951)
http://www.youtube.com/watch?v=896jnOb1fcI
Ricky Field - Scientist
Sally Field - Actress
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 3
Margaret Margaret MorlanMorlan
My mother was born on May 10, 1922, in Houston Texas. She died on Sunday November 6, 2011 in Malibu, California at age 89.
Margaret Field in “The Man From Planet X” (1951)
http://www.youtube.com/watch?v=896jnOb1fcI
Ricky Field - Scientist
Sally Field - Actress
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 4
The Berkeley YearsThe Berkeley YearsRick Field 1964 R. D. Field
University of California, Berkeley, 1962-66 (undergraduate)University of California, Berkeley, 1966-71 (graduate student)
Rick & Jimmie1968
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 5
The Berkeley YearsThe Berkeley YearsRick Field 1964 R. D. Field
University of California, Berkeley, 1962-66 (undergraduate)University of California, Berkeley, 1966-71 (graduate student)
meMy sister Sally!
Rick & Jimmie1968
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 6
The Berkeley YearsThe Berkeley YearsR. D. Field
University of California, Berkeley, 1962-66 (undergraduate)University of California, Berkeley, 1966-71 (graduate student)
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 7
The Berkeley YearsThe Berkeley YearsR. D. Field
University of California, Berkeley, 1962-66 (undergraduate)University of California, Berkeley, 1966-71 (graduate student)
My Ph.D. advisor!
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 8
The Berkeley YearsThe Berkeley YearsR. D. Field
University of California, Berkeley, 1962-66 (undergraduate)University of California, Berkeley, 1966-71 (graduate student)
My Ph.D. advisor!
J.D.JBob
Cahn
Chris Quiggme
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 9
Before FeynmanBefore Feynman--FieldField
Rick & Jimmie1968
Rick & Jimmie1970 Rick & Jimmie
1972 (pregnant!)
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 10
Before FeynmanBefore Feynman--FieldField
Rick & Jimmie1968
Rick & Jimmie1970 Rick & Jimmie
1972 (pregnant!)
Rick & Jimmie at CALTECH 1973
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 11
Toward and Understanding of Toward and Understanding of HadronHadron--HadronHadron CollisionsCollisions
From 7 GeV/c π0’s to 1 TeV 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 EventUnderlying Event
Initial-State Radiation
Final-State Radiation
1st hat!
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 12
“Feynman-Field Jet Model”
The FeynmanThe Feynman--Field Field DaysDays
FF1: “Quark Elastic Scattering as a Source of High Transverse MomentumMesons”, 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!
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 13
HadronHadron--HadronHadron CollisionsCollisions
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
“Black-Box Model”
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 14
HadronHadron--HadronHadron CollisionsCollisions
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
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”
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 15
QuarkQuark--Quark BlackQuark Black--Box ModelBox ModelFF1 1977Quark 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!
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 16
QuarkQuark--Quark BlackQuark Black--Box ModelBox ModelFF1 1977Quark 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.”
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 17
QuarkQuark--Quark BlackQuark Black--Box ModelBox ModelFF1 1977Predict
particle ratiosPredict
increase with increasing CM energy W
Predictoverall event topology
(FFF1 paper 1977)
“Beam-Beam Remnants”
7 GeV/c π0’s!
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 18
TelagramTelagram from Feynmanfrom FeynmanJuly 1976
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 19
TelagramTelagram from Feynmanfrom FeynmanJuly 1976
SAW CRONIN AM NOW CONVINCED WERE RIGHT TRACK QUICK WRITEFEYNMAN
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 20
Letter from FeynmanLetter from FeynmanJuly 1976
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 21
Letter from Feynman Page 1Letter from Feynman Page 1
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 22
Letter from Feynman Page 1Letter from Feynman Page 1
Spelling?
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 23
Letter from Feynman Page 3Letter from Feynman Page 3
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 24
Letter from Feynman Page 3Letter from Feynman Page 3It is fun!
Onward!
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 25
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
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 26
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.”
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 27
HadronHadron--HadronHadron CollisionsCollisionsProton-Proton or Proton-Antiproton Colliders:
u ud
u u
u ud
Ebeam ½Ebeam ½Ebeam
1/6Ebeam1/6Ebeam+ECM ~ ¹/3 Ebeam
Hadron Hadron ???
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 28
MonteMonte--Carlo SimulationCarlo Simulationof of HadronHadron--HadronHadron CollisionsCollisions
Color singlet proton collides with a color singlet antiproton.
Proton AntiProtonProton AntiProton
color string
color string
Beam Remnants
Beam Remnants
color string
color string
Beam Remnants
Beam Remnants
A red quark gets knocked out of the proton and a blue antiquarkgets 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.
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 29
MonteMonte--Carlo SimulationCarlo Simulationof of HadronHadron--HadronHadron CollisionsCollisions
Color singlet proton collides with a color singlet antiproton.
Proton AntiProtonProton AntiProton
A red quark gets knocked out of the proton and a blue antiquarkgets 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.
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 30
MonteMonte--Carlo SimulationCarlo Simulationof of HadronHadron--HadronHadron CollisionsCollisions
Color singlet proton collides with a color singlet antiproton.
Proton AntiProtonProton AntiProton
color string
color string
Beam Remnants
Beam Remnants
A red quark gets knocked out of the proton and a blue antiquarkgets 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.
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 31
MonteMonte--Carlo SimulationCarlo Simulationof of HadronHadron--HadronHadron CollisionsCollisions
Color singlet proton collides with a color singlet antiproton.
Proton AntiProtonProton 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 antiquarkgets 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.
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 32
Feynman Talk at Coral GablesFeynman Talk at Coral Gables(December 1976)(December 1976)
“Feynman-Field Jet Model”
1st transparency Last transparency
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 33
A Parameterization of A Parameterization of the Properties of Jetsthe Properties of Jets
Assumed that jets could be analyzed on a “recursive”principle.
Field-Feynman 1978
Original quark with flavor “a” and momentum P0
bb pair
(ba)
Let f(η)dη be the probability that the rank 1 meson leavesfractional momentum η to the remaining cascade, leaving quark “b” with momentum P1 = η1P0.
cc pair
(cb) Primary Mesons
Assume that the mesons originating from quark “b” are distributed in presisely the same way as the mesons which came from quark a (i.e. same function f(η)), leaving quark “c” with momentum P2 = η2P1 = η2η1P0.Add in flavor dependence by letting βu = probabliity of producing u-ubar pair, βd = probability of producing d-dbar pair, etc.
Let F(z)dz be the probability of finding a meson (independent of rank) with fractional mementum z of the original quark “a” within the jet.
Rank 2
continue
Calculate F(z) from f(η) and βi!
(bk) (ka)
Rank 1
Secondary Mesons(after decay)
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 34
A Parameterization of A Parameterization of the Properties of Jetsthe Properties of Jets
Assumed that jets could be analyzed on a “recursive”principle.
Field-Feynman 1978
Original quark with flavor “a” and momentum P0
bb pair
(ba)
Let f(η)dη be the probability that the rank 1 meson leavesfractional momentum η to the remaining cascade, leaving quark “b” with momentum P1 = η1P0.
cc pair
(cb) Primary Mesons
Assume that the mesons originating from quark “b” are distributed in presisely the same way as the mesons which came from quark a (i.e. same function f(η)), leaving quark “c” with momentum P2 = η2P1 = η2η1P0.Add in flavor dependence by letting βu = probabliity of producing u-ubar pair, βd = probability of producing d-dbar pair, etc.
Let F(z)dz be the probability of finding a meson (independent of rank) with fractional mementum z of the original quark “a” within the jet.
Rank 2
continue
Calculate F(z) from f(η) and βi!
(bk) (ka)
Rank 1
Secondary Mesons(after decay)
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 35
FeynmanFeynman--Field Jet ModelField Jet ModelR. P. Feynman
ISMD, Kaysersberg, France, June 12, 1977
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 36
FeynmanFeynman--Field Jet ModelField Jet ModelR. P. Feynman
ISMD, Kaysersberg, France, June 12, 1977
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, ....”
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 37
MonteMonte--Carlo SimulationCarlo Simulationof of HadronHadron--HadronHadron CollisionsCollisions
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)
PYTHIA 6.4yesterday
“FF” or “FW”Fragmentationthe past
today SHERPA PYTHIA 8 HERWIG++
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 38
The The FermilabFermilab TevatronTevatron
I joined CDF in January 1998.
Proton AntiProton2 TeV
Proton
AntiProton
1 mile CDF
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 39
The The FermilabFermilab TevatronTevatron
I joined CDF in January 1998.
Proton AntiProton2 TeV
Proton
AntiProton
1 mile CDF
CDF “SciCo” Shift December 12-19, 2008
Acquired 4728 nb-1 during 8 hour “owl” shift!
My wife Jimmie on shift with me!
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 40
High PHigh PTT JetsJets
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.”
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 41
High Energy PhysicsHigh Energy PhysicsProton-antiproton collisions at 2 TeV.
Proton AntiProton
Proton AntiProton2 TeV
Proton AntiProton3.2x10-7 J
Define EH to be the amount of energy required to light a 60 Watt light bulb for 1 second (EH = 60 Joules). 1 TeV = 1012 ev = 1.6×10-7 Joules and hence EH = 3.75×108 TeV.A proton-antiproton collisions at 2 TeVis equal to about 3.2×10-7 Joules which corresponds to about 1/200,000,000 EH! The energy is not high in every day standards but it is concentrated at a small point (i.e. large energy density).
The mass energy of a proton is about 1 GeV and the mass energy of a pion is about 140 MeV. Hence 2 TeV is equavelent to about 2,000 proton masses or about 14,000 pion masses and lots of hadrons are produced in a typical collision.
Proton AntiProton2 TeV
Lots of outgoing hadrons
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 42
High Energy PhysicsHigh Energy PhysicsProton-antiproton collisions at 2 TeV.
Proton AntiProton
Proton AntiProton2 TeV
Proton AntiProton3.2x10-7 J
Define EH to be the amount of energy required to light a 60 Watt light bulb for 1 second (EH = 60 Joules). 1 TeV = 1012 ev = 1.6×10-7 Joules and hence EH = 3.75×108 TeV.A proton-antiproton collisions at 2 TeVis equal to about 3.2×10-7 Joules which corresponds to about 1/200,000,000 EH! The energy is not high in every day standards but it is concentrated at a small point (i.e. large energy density).
The mass energy of a proton is about 1 GeV and the mass energy of a pion is about 140 MeV. Hence 2 TeV is equavelent to about 2,000 proton masses or about 14,000 pion masses and lots of hadrons are produced in a typical collision.
Proton AntiProton2 TeV
Lots of outgoing hadrons
Display of charged particles in the CDF
central tracker
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 43
Collider CoordinatesCollider Coordinates
The z-axis is defined to be the beam axis with the xy-plane being the “transverse” plane.
Proton AntiProton
z-axis
y-axis
x-axis
Beam Axis
Proton AntiProton z-axis
xz-plane x-axis Center-of-Mass Scattering Angle
θcm P
x-axis
“Transverse”xy-plane y-axis
Azimuthal Scattering Angle
φ
PT
θcm is the center-of-mass scattering angle and φ is the azimuthal angle. The “transverse” momentum of a particle is given by PT = P cos(θcm).
2o4
6o3
15o2
40o1
90o0
θcmη
Use η and φ to determine the direction of an outgoing particle, where η is the “pseudo-rapidity”defined by η = -log(tan(θcm/2)).
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 44
CDF CDF DiJetDiJet Event: Event: M(jjM(jj) ) ≈≈ 1.4 1.4 TeVTeVET
jet1 = 666 GeV ETjet2 = 633 GeV
Esum = 1,299 GeV M(jj) = 1,364 GeV
M(jj)/Ecm ≈ 70%!!
Proton-Antiproton Collisions at 1.96 TeV
CDF
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 45
QCD MonteQCD Monte--Carlo Models: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
“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.
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 46
QCD MonteQCD Monte--Carlo Models: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!
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 47
Traditional ApproachTraditional Approach
Look at charged particle correlations in the azimuthal angle Δφ relative to a leading object (i.e.CaloJet#1, ChgJet#1, PTmax, Z-boson). For CDF PTmin = 0.5 GeV/c ηcut = 1.
Charged Particle Δφ Correlations PT > PTmin |η| < ηcut
Leading ObjectDirection
Δφ
“Toward”
“Transverse” “Transverse”
“Away”
Define |Δφ| < 60o as “Toward”, 60o < |Δφ| < 120o as “Transverse”, and |Δφ| > 120o as “Away”.
Leading Calorimeter Jet or Leading Charged Particle Jet or
Leading Charged Particle orZ-Boson
-ηcut +ηcut
φ
2π
0 η
Leading Object
Toward Region
Transverse Region
Transverse Region
Away Region
Away Region
All three regions have the same area in η-φ space, Δη×Δφ = 2ηcut×120o = 2ηcut×2π/3. Construct densities by dividing by the area in η-φ space.
Charged Jet #1Direction
Δφ
“Transverse” “Transverse”
“Toward”
“Away”
“Toward-Side” Jet
“Away-Side” Jet
“Transverse” region very sensitive to the “underlying event”!
CDF Run 1 Analysis
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 48
Old PYTHIA default(more initial-state radiation)New PYTHIA default
(less initial-state radiation)
0.50.5PARP(83)
0.40.4PARP(84)
0.250.25PARP(90)
0.951.0PARP(86)
1.8 TeV1.8 TeVPARP(89)
4.0
0.9
2.0 GeV
4
1
Tune A
1.0PARP(67)
1.0PARP(85)
1.9 GeVPARP(82)
4MSTP(82)
1MSTP(81)
Tune BParameter
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) andSet A (PARP(67)=4)).
"Transverse" Charged Particle Density: dN/dηdφ
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 |η|<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 Feburary 25, 2000!
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 49
The New ForefrontThe New Forefront
The forefront of science is moving from the US to CERN (Geneva, Switzerland).
The LHC is designed to collide protons with protons at a center-of-mass energy of 14 TeV (seven times greater energy than Fermilab)!
ProtonProton14 TeV
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 50
The LHC at CERNThe LHC at CERN
Proton Proton14 TeV
6 miles
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 51
The LHC at CERNThe LHC at CERN
Me at CMS!
DarinProton Proton
14 TeV
6 miles
CMS at the LHC
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 52
The LHCThe LHC7 TeV on 7 TeV proton-proton collider, 27km ring• 7 times higher energy than the Tevatron at Fermilab
• Aim for 5 TeV for 2008• 100 times higher design luminosity than Tevatron (L=1034cm-2s-1)
1232 superconducting 8.4T dipole magnets @ T=1.9ºK• Largest cryogenic structure, 40 ktons of mass to cool
4 experiments
Start Date:September 10, 2008
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 53
Incident of September 19Incident of September 19thth 20082008Very impressive startVery impressive start--up with beam on September 10, 2008up with beam on September 10, 2008!
While making the last step of the dipole circuit in sector 34, tWhile making the last step of the dipole circuit in sector 34, to 9.3kA. At 8.7kA, o 9.3kA. At 8.7kA, development of resistive zone in the dipole bus bar splicedevelopment of resistive zone in the dipole bus bar splice between Q24 R3 and the between Q24 R3 and the neighboring dipoleneighboring dipole. . Electrical arc developed which punctured the helium Electrical arc developed which punctured the helium enclosure.enclosure.
14 months of repair!
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 54
MinMin--Bias Bias ““AssociatedAssociated””Charged Particle DensityCharged Particle Density
Shows the “associated” charged particle density in the “transverse” region as a function of PTmax for charged particles (pT > 0.5 GeV/c, |η| < 1, not including PTmax) for “min-bias” events at 0.2 TeV, 0.9 TeV, 1.96 TeV, 7 TeV, 10 TeV, 14 TeV predicted by PYTHIA Tune DW at the particle level (i.e. generator level).
PTmax Direction
Δφ
“Toward”
“Transverse” “Transverse”
“Away”
PTmax Direction
Δφ
“Toward”
“Transverse” “Transverse”
“Away”
RHIC Tevatron
0.2 TeV → 1.96 TeV(UE increase ~2.7 times)
PTmax Direction
Δφ
“Toward”
“Transverse” “Transverse”
“Away”
LHC
1.96 TeV → 14 TeV(UE increase ~1.9 times)
Linear scale!
"Transverse" Charged Particle Density: dN/dηdφ
0.0
0.4
0.8
1.2
0 5 10 15 20 25
PTmax (GeV/c)
"Tra
nsve
rse"
Cha
rged
Den
sity
Charged Particles (|η|<1.0, PT>0.5 GeV/c)
RDF Preliminarypy Tune DW generator level
Min-Bias 14 TeV
1.96 TeV
0.2 TeV
7 TeV
0.9 TeV
10 TeV
"Transverse" Charged Particle Density: dN/dηdφ
0.0
0.4
0.8
1.2
0 2 4 6 8 10 12 14
Center-of-Mass Energy (TeV)
"Tra
nsve
rse"
Cha
rged
Den
sity RDF Preliminary
py Tune DW generator level
Charged Particles (|η|<1.0, PT>0.5 GeV/c)
PTmax = 5.25 GeV/cRHIC
Tevatron900 GeV
LHC7
LHC14
LHC10
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 55
MinMin--Bias Bias ““AssociatedAssociated””Charged Particle DensityCharged Particle Density
Shows the “associated” charged particle density in the “transverse” region as a function of PTmax for charged particles (pT > 0.5 GeV/c, |η| < 1, not including PTmax) for “min-bias” events at 0.2 TeV, 0.9 TeV, 1.96 TeV, 7 TeV, 10 TeV, 14 TeV predicted by PYTHIA Tune DW at the particle level (i.e. generator level). Log scale!
"Transverse" Charged Particle Density: dN/dηdφ
0.0
0.4
0.8
1.2
0 5 10 15 20 25
PTmax (GeV/c)
"Tra
nsve
rse"
Cha
rged
Den
sity
Charged Particles (|η|<1.0, PT>0.5 GeV/c)
RDF Preliminarypy Tune DW generator level
Min-Bias 14 TeV
1.96 TeV
0.2 TeV
7 TeV
0.9 TeV
10 TeV
"Transverse" Charged Particle Density: dN/dηdφ
0.0
0.4
0.8
1.2
0.1 1.0 10.0 100.0
Center-of-Mass Energy (TeV)
"Tra
nsve
rse"
Cha
rged
Den
sity RDF Preliminary
py Tune DW generator level
Charged Particles (|η|<1.0, PT>0.5 GeV/c)
PTmax = 5.25 GeV/c
RHIC
Tevatron
900 GeV
LHC7
LHC14LHC10
PTmax Direction
Δφ
“Toward”
“Transverse” “Transverse”
“Away”
PTmax Direction
Δφ
“Toward”
“Transverse” “Transverse”
“Away”
LHC7 LHC14
7 TeV → 14 TeV(UE increase ~20%)
Linear on a log plot!
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 56
Conclusions November 2009Conclusions November 2009We are making good progress in understanding and modeling the “underlying event”. RHIC data at 200 GeV are very important!
It is clear now that the default value PARP(90) = 0.16 is not correct and the value should be closer to the Tune A value of 0.25.
The new Pythia pT ordered tunes (py64 S320 and py64 P329) are very similar to Tune A, Tune AW, and Tune DW. At present the new tunes do not fit the data better than Tune AW and Tune DW. However, the new tune are theoretically preferred!
Proton AntiProton
PT(hard)
Outgoing Parton
Outgoing Parton
Underlying EventUnderlying Event
Initial-State Radiation
Final-State Radiation
Need to measure “Min-Bias” and the “underlying event” at the LHC as soon as possible to see if there is new QCD physics to be learned!
All tunes with the default value PARP(90) = 0.16 are wrong and are overestimating the activity of min-bias and the underlying event at the LHC! This includes all my “T” tunes and the (old) ATLAS tunes! UE&MB@CMSUE&MB@CMS
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
ε = 0.16 (default)
ε = 0.25 (Set A))
The new and old PYTHIA tunes are beginning to converge and I believe we are finally in a position to make some legitimate predictions at the LHC!
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 57
LHC 2009 SummaryLHC 2009 SummaryNovember 20th 2009
• First beams around again
November 29th 2009• Both beams accelerated to 1.18 TeV simultaneously
December 8th 2009• 2x2 accelerated to 1.18 TeV• First collisions at Ecm = 2.36 TeV!
December 14th 2009• Stable 2x2 at 1.18 TeV• Collisions in all four experiments
LHC - highest energy collider
ProtonProton2.36 TeV900 GeV
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 58
““TransverseTransverse”” Charged Particle DensityCharged Particle Density
Fake data (from MC) at 900 GeV on the “transverse” charged particle density, dN/dηdφ, as defined by the leading charged particle (PTmax) and the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and |η| < 2. The fake data (from PYTHIA Tune DW) are generated at the particle level (i.e.generator level) assuming 0.5 M min-bias events at 900 GeV (361,595 events in the plot).
PT(chgjet#1) Direction
Δφ
“Toward”
“Transverse” “Transverse”
“Away”
"Transverse" Charged Particle Density: dN/dηdφ
0.0
0.2
0.4
0.6
0.8
0 2 4 6 8 10 12 14 16 18
PTmax or PT(chgjet#1) (GeV/c)
"Tra
nsve
rse"
Cha
rged
Den
sity
900 GeVCharged Particles (|η|<2.0, PT>0.5 GeV/c)
RDF PreliminaryFake Data
pyDW generator level ChgJet#1
PTmax
Rick FieldMB&UE@CMS WorkshopCERN, November 6, 2009
PTmax Direction
Δφ
“Toward”
“Transverse” “Transverse”
“Away”
Leading Charged Particle Jet, chgjet#1.
Leading Charged Particle, PTmax.
Prediction!
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 59
““TransverseTransverse”” Charge DensityCharge Density
PTmax Direction
Δφ
“Toward”
“Transverse” “Transverse”
“Away”
PTmax Direction
Δφ
“Toward”
“Transverse” “Transverse”
“Away”
LHC 900 GeV
LHC7 TeV
900 GeV → 7 TeV(UE increase ~ factor of 2)
"Transverse" Charged Particle Density: dN/dηdφ
0.0
0.4
0.8
1.2
0 2 4 6 8 10 12 14 16 18 20
PTmax (GeV/c)
"Tra
nsve
rse"
Cha
rged
Den
sity
Charged Particles (|η|<2.0, PT>0.5 GeV/c)
RDF Preliminarypy Tune DW generator level
900 GeV
7 TeV
Shows the charged particle density in the “transverse” region for charged particles (pT > 0.5 GeV/c, |η| < 2) at 900 GeV and 7 TeV as defined by PTmax from PYTHIA Tune DW and at the particle level (i.e. generator level).
factor of 2!
~0.4 → ~0.8
Rick FieldMB&UE@CMS WorkshopCERN, November 6, 2009
Prediction!
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 60
““TransverseTransverse”” Charged Particle DensityCharged Particle Density
Fake data (from MC) at 900 GeV on the “transverse” charged particle density, dN/dηdφ, as defined by the leading charged particle (PTmax) and the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and |η| < 2. The fake data (from PYTHIA Tune DW) are generated at the particle level (i.e.generator level) assuming 0.5 M min-bias events at 900 GeV (361,595 events in the plot).
"Transverse" Charged Particle Density: dN/dηdφ
0.0
0.2
0.4
0.6
0.8
0 2 4 6 8 10 12 14 16 18
PTmax or PT(chgjet#1) (GeV/c)
"Tra
nsve
rse"
Cha
rged
Den
sity
900 GeVCharged Particles (|η|<2.0, PT>0.5 GeV/c)
RDF PreliminaryFake Data
pyDW generator level ChgJet#1
PTmax
Monte-Carlo!
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 61
““TransverseTransverse”” Charged Particle DensityCharged Particle Density
Fake data (from MC) at 900 GeV on the “transverse” charged particle density, dN/dηdφ, as defined by the leading charged particle (PTmax) and the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and |η| < 2. The fake data (from PYTHIA Tune DW) are generated at the particle level (i.e.generator level) assuming 0.5 M min-bias events at 900 GeV (361,595 events in the plot).
"Transverse" Charged Particle Density: dN/dηdφ
0.0
0.2
0.4
0.6
0.8
0 2 4 6 8 10 12 14 16 18
PTmax or PT(chgjet#1) (GeV/c)
"Tra
nsve
rse"
Cha
rged
Den
sity
900 GeVCharged Particles (|η|<2.0, PT>0.5 GeV/c)
RDF PreliminaryFake Data
pyDW generator level ChgJet#1
PTmax
CMS preliminary data at 900 GeV on the “transverse” charged particle density, dN/dηdφ, as defined by the leading charged particle (PTmax) and the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and |η| < 2. The data are uncorrected and compared with PYTHIA Tune DW after detector simulation (216,215 events in the plot).
"Transverse" Charged Particle Density: dN/dηdφ
0.0
0.2
0.4
0.6
0.8
0 2 4 6 8 10 12 14 16 18
PTmax or PT(chgjet#1) (GeV/c)
"Tra
nsve
rse"
Cha
rged
Den
sity CMS Preliminary
data uncorrectedpyDW + SIM
900 GeV
ChgJet#1
PTmax
Charged Particles (|η|<2.0, PT>0.5 GeV/c) Real Data!Monte-Carlo!
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 62
LHC: March 30, 2010LHC: March 30, 2010First collisions with beam energies of 3.5 TeV (Ecm = 7 TeV)! Factor of 4.5 higher energy than the Tevatron.
Stable Beams at Ecm = 7 TeV!
ProtonProton7 TeV
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 63
LHC: March 30, 2010LHC: March 30, 2010First collisions with beam energies of 3.5 TeV (Ecm = 7 TeV)! Factor of 4.5 higher energy than the Tevatron.
Stable Beams at Ecm = 7 TeV!
ProtonProton7 TeV
UF Group at CERN Bld 40
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 64
LHC: March 30, 2010LHC: March 30, 2010First collisions with beam energies of 3.5 TeV (Ecm = 7 TeV)! Factor of 4.5 higher energy than the Tevatron.
Stable Beams at Ecm = 7 TeV!
ProtonProton7 TeV
UF Group at CERN Bld 40
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 65
LHC: March 30, 2010LHC: March 30, 2010First collisions with beam energies of 3.5 TeV (Ecm = 7 TeV)! Factor of 4.5 higher energy than the Tevatron.
Stable Beams at Ecm = 7 TeV!
ProtonProton7 TeV
UF Group at CERN Bld 40
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 66
CMS: March 30, 2010CMS: March 30, 2010
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 67
CMS: March 30, 2010CMS: March 30, 2010
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 68
PYTHIA Tune DWPYTHIA Tune DW
PTmax Direction
Δφ
“Toward”
“Transverse” “Transverse”
“Away”
"Transverse" Charged Particle Density: dN/dηdφ
0.0
0.4
0.8
1.2
0 2 4 6 8 10 12 14 16 18 20
PTmax (GeV/c)
"Tra
nsve
rse"
Cha
rged
Den
sity RDF Preliminary
ATLAS corrected dataTune DW generator level
900 GeV
7 TeV
Charged Particles (|η|<2.5, PT>0.5 GeV/c)
ATLAS preliminary data at 900 GeV and 7 TeV on the “transverse” charged particle density, dN/dηdφ, as defined by the leading charged particle (PTmax) for charged particles with pT > 0.5 GeV/c and |η| < 2.5. The data are corrected and compared with PYTHIA Tune DW at the generator level.
CMS preliminary data at 900 GeV and 7 TeVon the “transverse” charged particle density, dN/dηdφ, as defined by the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and |η| < 2. The data are uncorrected and compared with PYTHIA Tune DW after detector simulation.
"Transverse" Charged Particle Density: dN/dηdφ
0.0
0.4
0.8
1.2
0 5 10 15 20 25 30 35 40 45 50
PT(chgjet#1) GeV/c
Cha
rged
Par
ticle
Den
sity
900 GeV
CMS Preliminarydata uncorrected
pyDW + SIM
Charged Particles (|η|<2.0, PT>0.5 GeV/c)
7 TeV
CMS ATLAS
PT(chgjet#1) Direction
Δφ
“Toward”
“Transverse” “Transverse”
“Away”
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 69
PYTHIA Tune DWPYTHIA Tune DW
Ratio of CMS preliminary data at 900 GeVand 7 TeV on the “transverse” charged particle density, dN/dηdφ, as defined by the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and |η| < 2. The data are uncorrected and compared with PYTHIA Tune DW after detector simulation.
"Transverse" Charged Particle Density: dN/dηdφ
0.0
1.0
2.0
3.0
0 2 4 6 8 10 12 14 16 18
PT(chgjet#1) (GeV/c)
Rat
io: 7
TeV
/900
GeV
CMS Preliminarydata uncorrected
pyDW + SIM
Charged Particles (|η|<2.0, PT>0.5 GeV/c) 7 TeV / 900 GeV
CMS
CMS preliminary data at 900 GeV and 7 TeVon the “transverse” charged particle density, dN/dηdφ, as defined by the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and |η| < 2. The data are uncorrected and compared with PYTHIA Tune DW after detector simulation.
"Transverse" Charged Particle Density: dN/dηdφ
0.0
0.4
0.8
1.2
0 5 10 15 20 25 30 35 40 45 50
PT(chgjet#1) GeV/c
Cha
rged
Par
ticle
Den
sity
900 GeV
CMS Preliminarydata uncorrected
pyDW + SIM
Charged Particles (|η|<2.0, PT>0.5 GeV/c)
7 TeV
CMS
PT(chgjet#1) Direction
Δφ
“Toward”
“Transverse” “Transverse”
“Away”
Ratio
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 70
PYTHIA Tune DWPYTHIA Tune DW
Ratio of CMS preliminary data at 900 GeVand 7 TeV on the “transverse” charged particle density, dN/dηdφ, as defined by the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and |η| < 2. The data are uncorrected and compared with PYTHIA Tune DW after detector simulation.
Ratio of the ATLAS preliminary data at 900 GeV and 7 TeV on the “transverse” charged particle density, dN/dηdφ, as defined by the leading charged particle (PTmax) for charged particles with pT > 0.5 GeV/c and |η| < 2.5. The data are corrected and compared with PYTHIA Tune DW at the generator level.
"Transverse" Charged Particle Density: dN/dηdφ
0.0
1.0
2.0
3.0
0 2 4 6 8 10 12 14 16 18
PT(chgjet#1) (GeV/c)
Rat
io: 7
TeV
/900
GeV
CMS Preliminarydata uncorrected
pyDW + SIM
Charged Particles (|η|<2.0, PT>0.5 GeV/c) 7 TeV / 900 GeV
"Transverse" Charged Particle Density: dN/dηdφ
0.0
1.0
2.0
3.0
0 1 2 3 4 5 6 7 8 9 10 11 12
PTmax (GeV/c)
Rat
io: 7
TeV
/900
GeV
Charged Particles (|η|<2.5, PT>0.5 GeV/c)
RDF PreliminaryATLAS corrected datapyDW generator level
7 TeV / 900 GeV
CMS ATLAS
PTmax Direction
Δφ
“Toward”
“Transverse” “Transverse”
“Away”
PT(chgjet#1) Direction
Δφ
“Toward”
“Transverse” “Transverse”
“Away”
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 71
PYTHIA Tune DWPYTHIA Tune DW
I am surprised that the Tunes did not do a better job of predicting the behavior of the “underlying event” at 900 GeV and 7 TeV!
How well did we do at predicting the “underlying event” at 900 GeV and 7 TeV?
"Transverse" Charged Particle Density: dN/dηdφ
0.0
0.4
0.8
1.2
0 5 10 15 20 25 30 35 40 45 50
PT(chgjet#1) GeV/c
Cha
rged
Par
ticle
Den
sity
900 GeV
CMS Preliminarydata uncorrected
pyDW + SIM
Charged Particles (|η|<2.0, PT>0.5 GeV/c)
7 TeV
"Transverse" Charged Particle Density: dN/dηdφ
0.0
0.2
0.4
0.6
0.8
0 2 4 6 8 10 12 14 16 18
PTmax or PT(chgjet#1) (GeV/c)
"Tra
nsve
rse"
Cha
rged
Den
sity CMS Preliminary
data uncorrectedpyDW + SIM
900 GeV
ChgJet#1
PTmax
Charged Particles (|η|<2.0, PT>0.5 GeV/c)
"Transverse" Charged Particle Density: dN/dηdφ
0.0
1.0
2.0
3.0
0 2 4 6 8 10 12 14 16 18
PT(chgjet#1) (GeV/c)
Rat
io: 7
TeV
/900
GeV
CMS Preliminarydata uncorrected
pyDW + SIM
Charged Particles (|η|<2.0, PT>0.5 GeV/c) 7 TeV / 900 GeV
Tune DW Tune DW
Tune DW
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 72
PYTHIA Tune DWPYTHIA Tune DW
I am surprised that the Tunes did as well as they did at predicting the behavior of the “underlying event” at 900 GeV and 7 TeV!
How well did we do at predicting the “underlying event” at 900 GeV and 7 TeV?
"Transverse" Charged Particle Density: dN/dηdφ
0.0
0.4
0.8
1.2
0 5 10 15 20 25 30 35 40 45 50
PT(chgjet#1) GeV/c
Cha
rged
Par
ticle
Den
sity
900 GeV
CMS Preliminarydata uncorrected
pyDW + SIM
Charged Particles (|η|<2.0, PT>0.5 GeV/c)
7 TeV
"Transverse" Charged Particle Density: dN/dηdφ
0.0
0.2
0.4
0.6
0.8
0 2 4 6 8 10 12 14 16 18
PTmax or PT(chgjet#1) (GeV/c)
"Tra
nsve
rse"
Cha
rged
Den
sity CMS Preliminary
data uncorrectedpyDW + SIM
900 GeV
ChgJet#1
PTmax
Charged Particles (|η|<2.0, PT>0.5 GeV/c)
"Transverse" Charged Particle Density: dN/dηdφ
0.0
1.0
2.0
3.0
0 2 4 6 8 10 12 14 16 18
PT(chgjet#1) (GeV/c)
Rat
io: 7
TeV
/900
GeV
CMS Preliminarydata uncorrected
pyDW + SIM
Charged Particles (|η|<2.0, PT>0.5 GeV/c) 7 TeV / 900 GeV
Tune DW Tune DW
Tune DW
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 73
CMS CMS DiJetDiJet Event: Event: M(jjM(jj) ) ≈≈ 2 2 TeVTeVET
jet1 = 1.099 TeV ETjet2 = 935 GeV
M(jj) = 2.05 TeV
Proton-Proton Collisions at 7 TeV
M(jj)/Ecm ≈ 29%But M(jj) > 2 TeV!
CMS
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 74
7 7 GeVGeV ππ00’’s s →→ 1 1 TeVTeV JetsJets
7 GeV/c π0’s!
FF1
CMS
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 75
7 7 GeVGeV ππ00’’s s →→ 1 1 TeVTeV JetsJets
7 GeV/c π0’s!
FF1
CMS
Rick & Jimmie CALTECH 1973
Rick & Jimmie ISMD - Chicago 2013
Physoc Guest Lecture Glasgow October 17, 2013
Rick Field – Florida/CDF/CMS Page 76
7 7 GeVGeV ππ00’’s s →→ 1 1 TeVTeV JetsJets
7 GeV/c π0’s!
FF1
CMS
Rick & Jimmie CALTECH 1973
Rick & Jimmie ISMD - Chicago 2013
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