1 st workshop on energy scaling in hadron-hadron collisions

Fermilab Energy Scaling Workshop April 27, 2009

Rick Field – Florida/CDF/CMS

11stst Workshop on Energy Scaling Workshop on Energy Scalingin Hadron-Hadron Collisionsin Hadron-Hadron Collisions

Rick FieldUniversity of Florida

Outline of Talk

Proton AntiProton

PT(hard)

Outgoing Parton

Outgoing Parton

Underlying Event Underlying Event

Initial-State Radiation

Final-State Radiation

CMS at the LHCCDF Run 2

The early days of Feynman-Field Phenomenology.

Tuning the QCD Monte-Carlo model generators.

Studying “min-bias” collisions and the “underlying event” in Run 1 at CDF.

Rick’s View of Hadron Collisions Fermilab 2009

Studying the “associated” charged particle densities in “min-bias” collisions.



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




1st hat!



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

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”



QuarkQuark--Quark BlackQuark Black--Box ModelBox Model

FF1 1977 Quark Distribution Functionsdetermined from deep-inelastic

lepton-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.”



Quark-Quark Black-Box ModelQuark-Quark Black-Box Model

FF1 1977Predictparticle ratios

Predictincrease with increasing

CM energy W

Predictoverall event topology

(FFF1 paper 1977)

“Beam-Beam Remnants”

7 GeV/c 0’s!



Feynman Talk at Coral GablesFeynman Talk at Coral Gables (December 1976)(December 1976)

“Feynman-Field Jet Model”

1st transparency Last transparency



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.”



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()d be the probability that the rank 1 meson leaves fractional momentum to the remaining cascade, leaving quark “b” with momentum P1 = 1P0.

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()), leaving quark “c” with momentum P2 = 2P1 = 21P0.

Add in flavor dependence by letting u = probabliity of producing u-ubar pair, d = 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() and i!

(bk) (ka)

Rank 1

Secondary Mesons(after decay)



Feynman-Field Jet ModelFeynman-Field Jet Model

R. 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, ....”



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.”



CDF DiJet Event: M(jj) CDF DiJet Event: M(jj) ≈ 1.4 TeV≈ 1.4 TeV

ETjet1 = 666 GeV ET

jet2 = 633 GeV Esum = 1,299 GeV M(jj) = 1,364 GeV

M(jj)/Ecm ≈ 70%!!



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)

PYTHIA(“String” Fragmentation)

yesterday

“FF” or “FW” Fragmentationmy early days

today SHERPA PYTHIA 6.4 HERWIG++



The Fermilab TevatronThe Fermilab Tevatron

I joined CDF in January 1998.

Proton AntiProton 2 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!



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




“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

“Inelastic Non-Diffractive Component”



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



Hard Scattering

PT(hard)

Outgoing Parton

Outgoing Parton



Proton AntiProton


Proton AntiProton


“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!



-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

AverageAverage 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



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”


“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”



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

nsv

erse

" C

har

ged

Den

sity

CDF Min-Bias

CDF JET20CDF Run 1data uncorrected

1.8 TeV ||<1.0 PT>0.5 GeV/c

Charged Particle Jet #1 Direction

“Toward”


“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

har

ged

Den

sity

dN

/d

d d

PT

(1/

GeV

/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



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


final-state radiation outgoing jet Beam-Beam Remnants

or

“Soft” Component

Proton AntiProton

“Hard” Collision


final-state radiation outgoing parton

outgoing parton



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-off

PT0 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


Color String

Color String


Color String

Hard-Scattering Cut-Off PT0

1

2

3

4

5

100 1,000 10,000 100,000

CM Energy W (GeV)P

T0

(G

eV

/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




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

ran

sver

se"

Ch

arg

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



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)).


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

nsv

erse

" C

har

ged

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!



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 A

CDF 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.


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)

Ch

arg

ed D

ensi

ty d

N/d

d d

PT

(1/

GeV

/c)

Pythia 6.206 Set A

CDF 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!


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




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)

Ch

arg

ed D

ensi

ty d

N/d

d d

PT

(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 10,000 100,000

CM Energy W (GeV)

% o

f E

ven

ts

PT(hard) > 5 GeV/c

PT(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!



LHC?

PYTHIA Tune APYTHIA Tune ALHC Min-Bias PredictionsLHC Min-Bias Predictions



CDF Run 1 PCDF Run 1 PTT(Z)(Z)

Shows the Run 1 Z-boson pT distribution (<pT(Z)> ≈ 11.5 GeV/c) compared with PYTHIA Tune A (<pT(Z)> = 9.7 GeV/c), and PYTHIA Tune AW (<pT(Z)> = 11.7 GeV/c).

Parameter Tune A Tune AW

MSTP(81) 1 1

MSTP(82) 4 4


PARP(83) 0.5 0.5

PARP(84) 0.4 0.4

PARP(85) 0.9 0.9

PARP(86) 0.95 0.95


PARP(90) 0.25 0.25

PARP(62) 1.0 1.25

PARP(64) 1.0 0.2

PARP(67) 4.0 4.0

MSTP(91) 1 1

PARP(91) 1.0 2.1

PARP(93) 5.0 15.0

The Q2 = kT2 in s for space-like showers is scaled by PARP(64)!

Effective Q cut-off, below which space-like showers are not evolved.

UE Parameters

ISR Parameters

Intrensic KT

PYTHIA 6.2 CTEQ5LZ-Boson Transverse Momentum

0.00

0.04

0.08

0.12

0 2 4 6 8 10 12 14 16 18 20

Z-Boson PT (GeV/c)

PT

Dis

trib

uti

on

1/N

dN

/dP

T

CDF Run 1 Data

PYTHIA Tune A

PYTHIA Tune AW

CDF Run 1published

1.8 TeV

Normalized to 1

Tune used by the CDF-EWK group!



JetJet--Jet Correlations (DJet Correlations (DØ)Ø)

Jet#1-Jet#2 Distribution Jet#1-Jet#2

MidPoint Cone Algorithm (R = 0.7, fmerge = 0.5)

L = 150 pb-1 (Phys. Rev. Lett. 94 221801 (2005))Data/NLO agreement good. Data/HERWIG agreement

good.Data/PYTHIA agreement good provided PARP(67) =

1.0→4.0 (i.e. like Tune A, best fit 2.5).



CDF Run 1 PCDF Run 1 PTT(Z)(Z)

Shows the Run 1 Z-boson pT distribution (<pT(Z)> ≈ 11.5 GeV/c) compared with PYTHIA Tune DW, and HERWIG.

Parameter Tune DW Tune AW

MSTP(81) 1 1

MSTP(82) 4 4


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(90) 0.25 0.25

PARP(62) 1.25 1.25

PARP(64) 0.2 0.2

PARP(67) 2.5 4.0

MSTP(91) 1 1

PARP(91) 2.1 2.1

PARP(93) 15.0 15.0

UE Parameters

ISR Parameters

Intrensic KT

PYTHIA 6.2 CTEQ5L Z-Boson Transverse Momentum

0.00

0.04

0.08

0.12

0 2 4 6 8 10 12 14 16 18 20

Z-Boson PT (GeV/c)

PT

Dis

trib

uti

on

1/N

dN

/dP

T

CDF Run 1 Data

PYTHIA Tune DW

HERWIG

CDF Run 1published

1.8 TeV

Normalized to 1

Tune DW has a lower value of PARP(67) and slightly more MPI!

Tune DW uses D0’s perfered value of PARP(67)!



PYTHIA 6.2 TunesPYTHIA 6.2 TunesParameter Tune AW Tune DW Tune D6

PDF CTEQ5L CTEQ5L CTEQ6L

MSTP(81) 1 1 1

MSTP(82) 4 4 4

PARP(82) 2.0 GeV 1.9 GeV 1.8 GeV

PARP(83) 0.5 0.5 0.5

PARP(84) 0.4 0.4 0.4

PARP(85) 0.9 1.0 1.0

PARP(86) 0.95 1.0 1.0

PARP(89) 1.8 TeV 1.8 TeV 1.8 TeV

PARP(90) 0.25 0.25 0.25

PARP(62) 1.25 1.25 1.25

PARP(64) 0.2 0.2 0.2

PARP(67) 4.0 2.5 2.5

MSTP(91) 1 1 1

PARP(91) 2.1 2.1 2.1

PARP(93) 15.0 15.0 15.0

Intrinsic KT

ISR Parameter

UE Parameters

Uses CTEQ6L

All use LO s with = 192 MeV!

Tune A energy dependence!



PYTHIA 6.2 TunesPYTHIA 6.2 TunesParameter Tune DWT Tune D6T ATLAS

PDF CTEQ5L CTEQ6L CTEQ5L

MSTP(81) 1 1 1

MSTP(82) 4 4 4

PARP(82) 1.9409 GeV 1.8387 GeV 1.8 GeV

PARP(83) 0.5 0.5 0.5

PARP(84) 0.4 0.4 0.5

PARP(85) 1.0 1.0 0.33

PARP(86) 1.0 1.0 0.66

PARP(89) 1.96 TeV 1.96 TeV 1.0 TeV

PARP(90) 0.16 0.16 0.16

PARP(62) 1.25 1.25 1.0

PARP(64) 0.2 0.2 1.0

PARP(67) 2.5 2.5 1.0

MSTP(91) 1 1 1

PARP(91) 2.1 2.1 1.0

PARP(93) 15.0 15.0 5.0

Intrinsic KT

ISR Parameter

UE Parameters

All use LO s with = 192 MeV!

ATLAS energy dependence!

Tune A

Tune AW Tune B Tune BW

Tune D

Tune DWTune D6

Tune D6T

These are “old” PYTHIA 6.2 tunes! There are new 6.420 tunes by

Peter Skands (Tune S320, update of S0)Peter Skands (Tune N324, N0CR)

Hendrik Hoeth (Tune P329, “Professor”)



JIMMY at CDFJIMMY at CDFThe Energy in the “Underlying

Event” in High PT Jet Production

“Transverse” <Densities> vs PT(jet#1)

Jet #1 Direction

“Toward”


“Away”

"Transverse" PTsum Density: dPT/dd

0.0

0.4

0.8

1.2

1.6

0 50 100 150 200 250 300 350 400 450 500

PT(particle jet#1) (GeV/c)

"Tra

nsv

erse

" P

Tsu

m D

ensi

ty (

GeV

/c)

PY Tune A

HW

1.96 TeV

Charged Particles (||<1.0, PT>0.5 GeV/c)

CDF Run 2 Preliminarygenerator level theory

MidPoint R = 0.7 |(jet)| < 2

"Leading Jet"

JIMMY Default

JM325

"Transverse" ETsum Density: dET/dd

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MidPoint R = 0.7 |(jet)| < 2CDF Run 2 Preliminarygenerator level theory

"Leading Jet"

JIMMY Default

JM325

JIMMY: MPIJ. M. Butterworth

J. R. ForshawM. H. Seymour

JIMMY was tuned to fit the energy density in the “transverse” region for

“leading jet” events!JIMMY

Runs with HERWIG and adds multiple parton interactions!

PT(JIM)= 2.5 GeV/c.

PT(JIM)= 3.25 GeV/c.

Proton AntiProton

PT(hard)

Outgoing Parton

Outgoing Parton




The Drell-Yan JIMMY TunePTJIM = 3.6 GeV/c,

JMRAD(73) = 1.8JMRAD(91) = 1.8



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

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Associated DensityPTmax not included

CDF Preliminarydata uncorrected


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!

Min-Bias “Associated”Min-Bias “Associated”Charged Particle DensityCharged Particle Density



Associated Particle Density: dN/dd

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CDF Preliminarydata uncorrected

PTmaxPTmax not included


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”


“Away”

PTmax > 0.5 GeV/c

PTmax > 2.0 GeV/c

Min-Bias “Associated”Min-Bias “Associated”Charged Particle DensityCharged Particle Density Rapid rise in the particle

density in the “transverse” region as PTmax increases!


Rick Field – Florida/CDF/CMS Page 35

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

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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”


“Away”

Transverse Region Transverse

Region

PY Tune A





Shows the “associated” charged particle density in the “toward”, “away” and “transverse” regions as a function of PTmax for charged particles (pT > 0.5 GeV/c, || < 1, not including PTmax) for “min-bias” events at 1.96 TeV from PYTHIA Tune A (generator level).

PTmax Direction

“Toward”


“Away”

Associated Charged Particle Density: dN/dd

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Min-Bias1.96 TeV

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"Transverse"

"Away"

Shows 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 at 1.96 TeV with PTmax > 0.5, 1.0, 2.0, 5.0, and 10.0 GeV/c from PYTHIA Tune A (generator level).


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PTmax Direction

“Toward”


“Away”

~ factor of 2!



11stst Workshop on Energy Scaling Workshop on Energy Scalingin Hadron-Hadron Collisionsin Hadron-Hadron Collisions

Rick Field Talk 2 Tomorrow at 1:30pm

From Min-Bias to the Underlying Event

CDF Run 2 Underlying Event Studies

Comparing with the 630 GeV data

Rick Field Talk 3 Wednesday at 9:00am

From CDF to CMS

Extrapolating to the LHC

Tune S320 and P329 compared with Tune A,

DW, and DWT

1 st workshop on energy scaling in hadron-hadron collisions

Documents

hadronhadron collisionsfrom

hadron collisionswhat

quarkquark elastic scattering

bias collisions

quark crosssectionunknown

feynman talk

direct hard collisions

early days of feynman