Min-Bias and the Underlying Event in Run 2

QCD "Blessing" February 6, 2004

Rick Field - Florida/CDF Page 1

Min-Bias and theMin-Bias and theUnderlying Event in Run 2Underlying Event in Run 2

Min-Bias and the “Underlying Event” in Run II at CDF: The Run 2 analysis gives a more detailed look at the “underlying event” in hard scattering processes and compares the (uncorrected) data with PYTHIA Tune A and HERWIG after CDFSIM.

My graduate student, Alberto Cruz, will take over this analysis and bring it to “publication level” (within the next year!).

Proton AntiProton

PT(hard)

Outgoing Parton

Outgoing Parton

Underlying Event Underlying Event

Initial-State Radiation

Final-State Radiation

CERN MC4LHC WorkshopJuly 2003

During the workshop the theorists, ATLAS/CMS experimenters, and I constructed a “wish list” of data

from CDF relating to “min-bias” and the “underlying event” and I promised to do the analysis

and have the data available by the time of the Santa Barbara workshop in February 2004.

The “underlying event” consists of hard initial & final-state radiation

plus the “beam-beam remnants” and possible multiple parton interactions.

CDF NotesCDF/ANAL/CDF/CDFR/6403CDF/ANAL/CDF/CDFR/6759CDF/ANAL/CDF/CDFR/6819



Jet #1 Direction

“Transverse” “Transverse”

“Toward”

“Away”

“Toward-Side” Jet

“Away-Side” Jet

““Transverse” RegionTransverse” Regionas defined by the Leading Jetas defined by the Leading Jet

Look at charged particle correlations in the azimuthal angle relative to the leading calorimeter jet (JetClu R = 0.7, || < 2).

Define || < 60o as “Toward”, 60o < || < 120o as “Transverse”, and || > 120o as “Away”. The “transverse region” is very sensitive to the “underlying event”.

All three regions have the same size in - space, x = 2x120o = 4/3.

Charged Particle Correlations pT > 0.5 GeV/c || < 1“Transverse” region is

very sensitive to the “underlying event”!

-1 +1

2

0

Leading Jet

Toward Region

Transverse Region

Transverse Region

Away Region

Away Region

Look at the charged particle density in the “transverse” region!

Jet #1 Direction

“Toward”


“Away”



-1 +1

2

0

1 charged particle

dNchg/dd = 1/4 = 0.08

Particle DensitiesParticle Densities

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

-1 +1

2

0

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

3 charged particles

dNchg/dd = 3/4 = 0.24

CDF Run 2 “Min-Bias” = 4 = 12.6

Divide by 4



-1 +1

2

0

Leading Jet

Toward Region

Transverse Region

Transverse Region

Away Region

Away Region

““Transverse”Transverse”Particle DensitiesParticle Densities

Study the charged particles (pT > 0.5 GeV/c, || < 1) in the “transverse” region 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

1 charged particle in the “transverse” region

dNchg/dd = 1/(4 = 0.24

Jet #1 Direction

“Toward”


“Away”

Area = 2(4)/6 = 4/3



Charged Particle DensityCharged Particle Density Dependence Dependence

Shows the dependence of the charged particle density, dNchg/dd, for charged particles in the range pT > 0.5 GeV/c and || < 1 relative to jet#1 (rotated to 270o) for “leading jet” events 30 < ET(jet#1) < 70 GeV.

Also shows charged particle density, dNchg/dd, for charged particles in the range pT > 0.5 GeV/c and || < 1 for “min-bias” collisions.

Leading Jet

Charged Particle Density: dN/dd

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CDF Preliminarydata uncorrected

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

30 < ET(jet#1) < 70 GeV

"Transverse" Region

Jet#1

Jet #1 Direction


“Toward”

“Away”


“Away-Side” Jet

Jet #1 Direction


“Toward”

“Away”


“Away-Side” Jet

Jet #3

Min-Bias0.25 per unit -

Log Scale!




Look at the “transverse” region as defined by the leading jet (JetClu R = 0.7, || < 2) or by the leading two jets (JetClu R = 0.7, || < 2). “Back-to-Back” events are selected to have at least two jets with Jet#1 and Jet#2 nearly “back-to-back” (12 > 150o) with almost equal transverse energies (ET(jet#2)/ET(jet#1) > 0.8).


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30 < ET(jet#1) < 70 GeV

"Transverse" Region

Jet#1

Jet #1 Direction

“Toward”


“Away”

Jet #1 Direction

“Toward”


“Away”

Jet #2 Direction

Shows the dependence of the charged particle density, dNchg/dd, for charged particles in the range pT > 0.5 GeV/c and || < 1 relative to jet#1 (rotated to 270o) for 30 < ET(jet#1) < 70 GeV for “Leading Jet” and “Back-to-Back” events.


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Back-to-Back

Leading Jet

Min-Bias



30 < ET(jet#1) < 70 GeV

"Transverse" Region

Jet#1

Refer to this as a “Leading Jet” event

Refer to this as a “Back-to-Back” event

Su

bset




Jet #1 Direction

“Toward”


“Away”

Jet #1 Direction

“Toward”


“Away”

Jet #2 Direction

Shows the dependence of the charged particle density, dNchg/dd, for charged particles in the range pT > 0.5 GeV/c and || < 1 relative to jet#1 (rotated to 270o) for 30 < ET(jet#1) < 70 GeV for “Leading Jet” and “Back-to-Back” events.

“Leading Jet”

“Back-to-Back”

Charged Particle Density: dN/dd272

276 280 284288

292296

300304

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360

4

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6064

6872

76808488

9296100104

108112

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248252

256260 264 268


30 < ET(jet#1) < 70 GeV


"Transverse" Region

"Transverse" Region

Jet#1

Back-to-BackLeading Jet

0.5

1.0

1.5

2.0

Polar Plot



““Transverse” Charge DensityTransverse” Charge Densityversus Eversus ETT(jet#1) (jet#1)

Jet #1 Direction

“Toward”


“Away”

Jet #1 Direction

“Toward”


“Away”

Jet #2 Direction

Shows the average charged particle density, dNchg/dd, in the “transverse” region (pT > 0.5 GeV/c, || < 1) versus ET(jet#1) for “Leading Jet” and “Back-to-Back” events.

“Leading Jet”

“Back-to-Back”

"AVE Transverse" Charge Density: dN/dd

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ET(jet#1) (GeV)

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CDF Run 2 Preliminarydata uncorrected

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

Leading Jet

Back-to-Back

Min-Bias0.25 per unit -



““Transverse” Charge DensityTransverse” Charge Densityversus Eversus ETT(jet#1) (jet#1)

Jet #1 Direction

“Toward”


“Away”

Jet #1 Direction

“Toward”


“Away”

Jet #2 Direction


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30 < ET(jet#1) < 70 GeV

Min-Bias



Leading Jet

"Transverse" Region

Jet#1


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30 < ET(jet#1) < 70 GeV

Min-Bias



Back-to-Back

"Transverse" Region

Jet#1


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ET(jet#1) (GeV)

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Leading Jet

Back-to-Back 30-70 GeV 95-130

GeV

Very little dependence on ET(jet#1) in the “transverse”

region for “back-to-back” events!



““Transverse” PTsum DensityTransverse” PTsum Densityversus Eversus ETT(jet#1) (jet#1)

Jet #1 Direction

“Toward”


“Away”

Jet #1 Direction

“Toward”


“Away”

Jet #2 Direction

Shows the average charged PTsum density, dPTsum/dd, in the “transverse” region (pT > 0.5 GeV/c, || < 1) versus ET(jet#1) for “Leading Jet” and “Back-to-Back” events.

“Leading Jet”

“Back-to-Back”

"AVE Transverse" PTsum Density: dPT/dd

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Back-to-Back

Leading Jet

1.96 TeV

Min-Bias0.24 GeV/c per unit -



““Transverse” PTsum DensityTransverse” PTsum Densityversus Eversus ETT(jet#1) (jet#1)

Jet #1 Direction

“Toward”


“Away”

Jet #1 Direction

“Toward”


“Away”

Jet #2 Direction

30-70 GeV 95-130 GeV


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Back-to-Back

Leading Jet

1.96 TeV

Charged PTsum Density: dPT/dd

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30 < ET(jet#1) < 70 GeV

Min-Bias

Leading Jet



Jet#1

"Transverse" Region


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30 < ET(jet#1) < 70 GeV

Min-Bias

Back-to-Back



Jet#1

"Transverse" Region

Very little dependence on ET(jet#1) in the “transverse”

region for “back-to-back” events!



““Transverse” Charge DensityTransverse” Charge Density PYTHIA Tune A vs HERWIG PYTHIA Tune A vs HERWIG

Jet #1 Direction

“Toward”


“Away”

Jet #1 Direction

“Toward”


“Away”

Jet #2 Direction

Shows the average charged particle density, dNchg/dd, in the “transverse” region (pT > 0.5 GeV/c, || < 1) versus ET(jet#1) for “Leading Jet” and “Back-to-Back” events.

“Leading Jet”

“Back-to-Back”


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ET(jet#1) (GeV)

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CDF Preliminarydata uncorrectedtheory + CDFSIM


Leading Jet

Back-to-Back

PY Tune A

HW

Now look in detail at “back-to-back” events in the region 30 < ET(jet#1) < 70 GeV!


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ET(jet#1) (GeV)

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Leading Jet

Back-to-Back

Compares the (uncorrected) data with PYTHIA Tune A and HERWIG after CDFSIM.



Charged Particle DensityCharged Particle DensityPYTHIA Tune A vs HERWIG PYTHIA Tune A vs HERWIG


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Back-to-Back

PY Tune A


30 < ET(jet#1) < 70 GeVCharged Particles (||<1.0, PT>0.5 GeV/c)

"Transverse" Region

Jet#1

Data - Theory: Charged Particle Density dN/dd

-1.0

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0.0

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Da

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Back-to-Back30 < ET(jet#1) < 70 GeV

PYTHIA Tune A

Jet#1

"Transverse" Region


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HERWIG



"Transverse" Region

Jet#1


-1.0

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HERWIG

Jet#1

"Transverse" Region

HERWIG (without multiple parton interactions) produces too few charged

particles in the “transverse” region for 30 < ET(jet#1) < 70 GeV!





-1.0

-0.5

0.0

0.5

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0 30 60 90 120 150 180 210 240 270 300 330 360

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PYTHIA Tune A

Jet#1

"Transverse" Region


-1.0

-0.5

0.0

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HERWIG

Jet#1

"Transverse" Region


-1.0

-0.5

0.0

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HERWIG + 0.1

Jet#1

"Transverse" Region

dN/dd + 0.1

Add 0.1 charged particles per unit - to HERWIG density, dNchg/dd.

This corresponds to 0.1 x 4 = 1.3 particles in the entire range pT > 0.5 GeV/c, || < 1.



““Transverse” PTsum DensityTransverse” PTsum Density PYTHIA Tune A vs HERWIG PYTHIA Tune A vs HERWIG

Jet #1 Direction

“Toward”


“Away”

Jet #1 Direction

“Toward”


“Away”

Jet #2 Direction

Shows the average charged PTsum density, dPTsum/dd, in the “transverse” region (pT > 0.5 GeV/c, || < 1) versus ET(jet#1) for “Leading Jet” and “Back-to-Back” events.

“Leading Jet”

“Back-to-Back”


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Back-to-Back

Leading Jet

PY Tune A

HW

1.96 TeV


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Back-to-Back

Leading Jet

1.96 TeV

Compares the (uncorrected) data with PYTHIA Tune A and HERWIG after CDFSIM.




Charged PTsum DensityCharged PTsum DensityPYTHIA Tune A vs HERWIG PYTHIA Tune A vs HERWIG


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PY Tune A30 < ET(jet#1) < 70 GeVCharged Particles

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


Jet#1"Transverse" Region


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HERWIG30 < ET(jet#1) < 70 GeVCharged Particles

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


Jet#1

"Transverse" Region

Data - Theory: Charged PTsum Density dPT/dd

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PYTHIA Tune A

Jet#1

"Transverse" Region


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30 < ET(jet#1) < 70 GeVBack-to-Back

HERWIG

Jet#1

"Transverse" Region

HERWIG (without multiple parton interactions) does not produces

enough PTsum in the “transverse” region for 30 < ET(jet#1) < 70 GeV!





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PYTHIA Tune A

Jet#1

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HERWIG

Jet#1

"Transverse" Region


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HERWIG + 0.2 GeV/c

Jet#1

"Transverse" Region

Add 0.2 GeV/c per unit - to HERWIG scalar PTsum density, dPTsum/dd.

This corresponds to 0.2 x 4 = 2.5 GeV/c in the entire range pT > 0.5 GeV/c, || < 1.

dPT/dd + 0.2 GeV/c308 MeV in R = 0.7 cone!




““Transverse” Charge DensityTransverse” Charge Density PYTHIA Tune A vs HERWIG PYTHIA Tune A vs HERWIG

Jet #1 Direction

“Toward”


“Away”

Jet #1 Direction

“Toward”


“Away”

Jet #2 Direction

Shows the average charged particle density, dNchg/dd, in the “transverse” region (pT > 0.5 GeV/c, || < 1) versus ET(jet#1) for “Leading Jet” and “Back-to-Back” events compared with PYTHIA Tune A and HERWIG after CDFSIM.

“Leading Jet”

“Back-to-Back”


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ET(jet#1) (GeV)

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Leading Jet

Back-to-Back

PY Tune A

HW





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PY Tune A


95 < ET(jet#1) < 130 GeVCharged Particles

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

"Transverse" Region

Jet#1


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HERWIG


95 < ET(jet#1) < 130 GeV


"Transverse" Region

Jet#1


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CDF Preliminarydata uncorrectedtheory + CDFSIM Charged Particles

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


PYTHIA Tune A

Jet#1

"Transverse" Region


-1.6

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CDF Preliminarydata uncorrectedtheory + CDFSIM Charged Particles

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


HERWIG

Jet#1

"Transverse" Region

HERWIG (without multiple parton interactions) agrees much better in the “transverse” region

for 95 < ET(jet#1) < 130 GeV!




““Transverse” PTsum DensityTransverse” PTsum Density PYTHIA Tune A vs HERWIG PYTHIA Tune A vs HERWIG

Jet #1 Direction

“Toward”


“Away”

Jet #1 Direction

“Toward”


“Away”

Jet #2 Direction

Shows the average charged PTsum density, dPTsum/dd, in the “transverse” region (pT > 0.5 GeV/c, || < 1) versus ET(jet#1) for “Leading Jet” and “Back-to-Back” events compared with PYTHIA Tune A and HERWIG after CDFSIM.

“Leading Jet”

“Back-to-Back”


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Back-to-Back

Leading Jet

PY Tune A

HW

1.96 TeV





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PY Tune A95 < ET(jet#1) < 130 GeV





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PYTHIA Tune A

Jet#1

"Transverse" Region


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HERWIG

Jet#1

"Transverse" Region

HERWIG (without multiple parton interactions) agrees much better in the “transverse” region

for 95 < ET(jet#1) < 130 GeV!



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

Use the maximum pT charged particle in the event, PTmax, to define a direction and look at the the “associated” density, dNchg/dd.

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.

PTmax Direction

Correlations in


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Charge Density

Min-Bias

“Associated” densities do not include PTmax!

Highest pT charged particle!




Associated Particle Density: dN/dd

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PTmax > 1.0 GeV/c

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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”

Rapid rise in the particle density in the “transverse” region as PTmax increases!




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


PTsum Density

Associated DensityPTmax not included

Min-Bias

Min-BiasMin-Bias “Associated” “Associated”Charged PTsum DensityCharged PTsum Density

Use the maximum pT charged particle in the event, PTmax, to define a direction and look at the the “associated” PTsum density, dPTsum/dd.

Shows the data on the dependence of the “associated” charged PTsum density, dPTsum/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, dPTsum/dd, for “min-bias” events.

PTmax Direction

Correlations in

“Associated” densities do not include PTmax!

Highest pT charged particle!




PTmax Direction

Correlations in

Shows the data on the dependence of the “associated” charged PTsum density, dPTsum/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

PTmax Direction

“Toward”


“Away”

Associated PTsum Density: dPT/dd

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PTmax



PTmax not included Min-Bias

Ave Min-Bias0.24 GeV/c per unit -

Rapid rise in the PTsum density in the “transverse” region as PTmax increases!




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


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PY Tune A

PTmax > 0.5 GeV/c

PY Tune A


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




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PY Tune A

PTmax > 0.5 GeV/c

PY Tune A

PTmax


(||<1.0, PT>0.5 GeV/c) PTmax not included

PY Tune A 1.96 TeV


Shows the data on the dependence of the “associated” charged PTsum density, dPTsum/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

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



Back-to-BackBack-to-Back “Associated” “Associated”Charged Particle DensitiesCharged Particle Densities

Use the leading jet in “back-to-back” events to define the “transverse” region and look at the maximum pT charged particle in the “transverse” region, PTmaxT.

“Associated” densities do not include PTmaxT!

Jet #1 Direction

“Toward”

“TransMIN” “TransMAX”

PTmaxT

Jet #2 Direction

“Away”

Jet#1 Region

PTmaxT Direction

Jet#2 Region

PTmaxT Direction

Jet#1 Region

Jet#2 Region

Look at the dependence of the “associated” charged particle and PTsum densities, dNchg/dd and dPTsum/dd for charged particles (pT > 0.5 GeV/c, || < 1, not including PTmaxT) relative to PTmaxT.

Rotate so that PTmaxT is at the center of the plot (i.e. 180o).

Maximum pT particle in the “transverse” region!



Back-to-BackBack-to-Back “Associated” “Associated”Charged Particle DensityCharged Particle Density

PTmaxT Direction

Jet#1 Region

Jet#2 Region

Look at the dependence of the “associated” charged particle density, dNchg/dd for charged particles (pT > 0.5 GeV/c, || < 1, not including PTmaxT) relative to PTmaxT (rotated to 180o) for PTmaxT > 0.5 GeV/c, PTmaxT > 1.0 GeV/c and PTmaxT > 2.0 GeV/c, for “back-to-back” events with 30 < ET(jet#1) < 70 GeV .

Shows “jet structure” in the “transverse” region (i.e. the “birth” of the 3rd & 4th jet).


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PTmaxT > 1.0 GeV/c

PTmaxT > 0.5 GeV/c


PTmaxT



PTmaxT not included

"Jet#1" Region

Jet#2 Region

Jet #1

Jet #2

Jet #4


Jet #3

Log Scale!

??



Back-to-BackBack-to-Back “Associated” “Associated”Charged PTsum DensityCharged PTsum Density

PTmaxT Direction

Jet#1 Region

Jet#2 Region

Look at the dependence of the “associated” charged particle density, dPTsum/dd for charged particles (pT > 0.5 GeV/c, || < 1, not including PTmaxT) relative to PTmaxT (rotated to 180o) for PTmaxT > 0.5 GeV/c, PTmaxT > 1.0 GeV/c and PTmaxT > 2.0 GeV/c, for “back-to-back” events with 30 < ET(jet#1) < 70 GeV .

Shows “jet structure” in the “transverse” region (i.e. the “birth” of the 3rd & 4th jet).

Jet#2 Region

Jet #1

Jet #2

Jet #4

Jet #3


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PTmaxT > 1.0 GeV/c

PTmaxT > 0.5 GeV/c




"Jet#1" Region

PTmaxT

PTmaxT not included


Log Scale!

??




Jet#1 Region

PTmaxT Direction

Jet#2 Region


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Den

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Back-to-Back

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"Transverse" Region

PTmaxT Jet#1

Associated DensityPTmaxT not included

Shows the dependence of the “associated” charged particle density, dNchg/dd for charged particles (pT > 0.5 GeV/c, || < 1, not including PTmaxT) relative to PTmaxT (rotated to 180o) for PTmaxT > 0.5 GeV/c, PTmaxT > 1.0 GeV/c and PTmaxT > 2.0 GeV/c, for “back-to-back” events with 30 < ET(jet#1) < 70 GeV.

Shows dependence of the charged particle density, dNchg/dd for charged particles (pT > 0.5 GeV/c, || < 1) relative to jet#1 (rotated to 270o) for “back-to-back events” with 30 < ET(jet#1) < 70 GeV.

Jet #1 Direction

“Toward”


“Away”

Jet #2 Direction

It is more probable to find a particle accompying PTmaxT than it is to find a particle in

the “transverse” region!

“Back-to-Back”“associated” density

“Back-to-Back”charge density




Jet#1 Region

PTmaxT Direction

Jet#2 Region

Shows the dependence of the “associated” charged particle density, dNchg/dd, pT > 0.5 GeV/c, || < 1 (not including PTmaxT) relative to PTmaxT (rotated to 180o) and the charged particle density, dNchg/dd, pT > 0.5 GeV/c, || < 1 relative to jet#1 (rotated to 270o) for “back-to-back events” with 30 < ET(jet#1) < 70 GeV.

Jet #1 Direction

“Toward”


“Away”

Jet #2 Direction


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"Transverse" Region "Transverse"

Region

Jet#1

Associated DensityPTmaxT not included

PTmaxT

Polar Plot

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Jet#1 Region

PTmaxT Direction

Jet#2 Region

Shows the dependence of the “associated” charged particle density, dNchg/dd, pT > 0.5 GeV/c, || < 1, PTmaxT > 2.0 GeV/c (not including PTmaxT) relative to PTmaxT (rotated to 180o) and the charged particle density, dNchg/dd, pT > 0.5 GeV/c, || < 1, relative to jet#1 (rotated to 270o) for “back-to-back events” with 30 < ET(jet#1) < 70 GeV.

Jet #1 Direction

“Toward”


“Away”

Jet #2 Direction


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Region

Jet#1

Associated DensityPTmaxT > 2 GeV/c

(not included)

PTmaxT

Polar Plot



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2.0



Jet TopologiesJet Topologies

Jet#1 Region

PTmaxT Direction

Jet#2 Region

Shows the dependence of the “associated” charged particle density, dNchg/dd, pT > 0.5 GeV/c, || < 1, PTmaxT > 2.0 GeV/c (not including PTmaxT) relative to PTmaxT (rotated to 180o) and the charged particle density, dNchg/dd, pT > 0.5 GeV/c, || < 1, relative to jet#1 (rotated to 270o) for “back-to-back events” with 30 < ET(jet#1) < 70 GeV.


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Region

Jet#1

Associated DensityPTmaxT > 2 GeV/c

(not included)

PTmaxT

Polar Plot

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Jet #3

Jet #3

Jet #1

Jet #1

Jet #2

Jet #2

Jet #4

Jet #4

QCD Three Jet TopologyQCD Four Jet Topology

Proton AntiProton

QCD 2-to-4 Scattering

PT(hard)

Outgoing Parton

Outgoing Parton


Initial-State Radiation



Proton AntiProton

Multiple Parton Interactions

PT(hard)

Outgoing Parton

Outgoing Parton


Outgoing Parton

Outgoing Parton





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PTmaxT

PTmaxT > 2.0 GeV/c (not included)

"Jet#1" Region

Back-to-Back

PTmaxT Direction

Jet#1 Region

Jet#2 Region

Look at the dependence of the “associated” charged particle density, dNchg/dd, pT > 0.5 GeV/c, || < 1 (not including PTmaxT) relative to PTmaxT (rotated to 180o) for PTmaxT > 2.0 GeV/c for “back-to-back” events with 30 < ET(jet#1) < 70 GeV and 95 < ET(jet#1) < 130 GeV.

Jet#2 Region

Very little dependence on ET(jet#1) in the “transverse” region for “back-to-back” events!

Log Scale!




PTmaxT Direction

Jet#1 Region

Jet#2 Region

Look at the dependence of the “associated” charged PTsum density, dPTsum/dd, pT > 0.5 GeV/c, || < 1 (not including PTmaxT) relative to PTmaxT (rotated to 180o) for PTmaxT > 2.0 GeV/c for “back-to-back” events with 30 < ET(jet#1) < 70 GeV and 95 < ET(jet#1) < 130 GeV.

Jet#2 Region

Very little dependence on ET(jet#1) in the “transverse” region for “back-to-back” events!


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30 < ET(jet#1) < 70 GeV


Back-to-BackCharged Particles (||<1.0, PT>0.5 GeV/c)

"Jet#1" Region

PTmaxT


Log Scale!



““Back-to-Back” vs “MinBias”Back-to-Back” vs “MinBias”“Associated” Charge Density“Associated” Charge Density

“Back-to-Back”“Associated” Density

“Min-Bias”“Associated” Density


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PTmaxTPTmax

PTmaxT, PTmax not included


Min-Bias

PTmax Direction

Correlations in

PTmaxT Direction

Jet#1 Region

Jet#2 Region

Shows the dependence of the “associated” charged particle density, dNchg/dd for pT > 0.5 GeV/c, || < 1 (not including PTmaxT) relative to PTmaxT (rotated to 180o) for PTmaxT > 2.0 GeV/c, for “back-to-back” events with 30 < ET(jet#1) < 70 GeV.

Shows the data on the dependence of the “associated” charged particle density, dNchg/dd, pT > 0.5 GeV/c, || < 1 (not including PTmax) relative to PTmax (rotated to 180o) for “min-bias” events with PTmax > 2.0 GeV/c.


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PTmaxTPTmax


30 < ET(jet#1) < 70 GeV

Min-Bias x 1.65

“Birth” of jet#1 in “min-bias” collisions!

“Birth” of jet#3 in the “transverse” region!

Log Scale!



““Back-to-Back” vs “MinBias”Back-to-Back” vs “MinBias”“Associated” PTsum Density“Associated” PTsum Density

“Back-to-Back”“Associated” Density

“Min-Bias”“Associated” Density

PTmax Direction

Correlations in

PTmaxT Direction

Jet#1 Region

Jet#2 Region

Shows the dependence of the “associated” charged particle density, dNchg/dd for pT > 0.5 GeV/c, || < 1 (not including PTmaxT) relative to PTmaxT (rotated to 180o) for PTmaxT > 2.0 GeV/c, for “back-to-back” events with 30 < ET(jet#1) < 70 GeV.

Shows the data on the dependence of the “associated” charged particle density, dNchg/dd, pT > 0.5 GeV/c, || < 1 (not including PTmax) relative to PTmax (rotated to 180o) for “min-bias” events with PTmax > 2.0 GeV/c.


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PTmax > 2.0 GeV/c CDF Preliminarydata uncorrected

PTmaxPTmaxT



30 < ET(jet#1) < 70 GeV

Min-Bias


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PTmax > 2.0 GeV/c CDF Preliminarydata uncorrected

PTmaxPTmaxT



30 < ET(jet#1) < 70 GeV

Min-Bias x 1.65

“Birth” of jet#3 in the “transverse” region!

“Birth” of jet#1 in “min-bias” collisions!

Log Scale!



““Associated” Charge DensityAssociated” Charge DensityPYTHIA Tune A vs HERWIGPYTHIA Tune A vs HERWIG


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Data - Theory: Associated Particle Density dN/dd

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PTmaxT "Jet#1" Region

PTmaxT not included


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PTmaxT not included

HERWIG (without multiple parton interactions) too few “associated”

particles in the direction of PTmaxT!

And HERWIG (without multiple parton interactions) too few particles in the direction opposite of PTmaxT!



““Associated” PTsum DensityAssociated” PTsum DensityPYTHIA Tune A vs HERWIGPYTHIA Tune A vs HERWIG


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PTmaxT not included

Data - Theory: Associated PTsum Density dPT/dd

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HERWIG PTmaxT

PTmaxT not included

"Jet#1" Region

HERWIG (without multiple parton interactions) does not produce

enough “associated” PTsum in the direction of PTmaxT!

And HERWIG (without multiple parton interactions) does not

produce enough PTsum in the direction opposite of PTmaxT!



““Associated” Charge DensityAssociated” Charge DensityPYTHIA Tune A vs HERWIGPYTHIA Tune A vs HERWIG


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HERWIG



For PTmaxT > 2.0 GeV both PYTHIA and HERWIG produce

slightly too many “associated” particles in the direction of PTmaxT!

But HERWIG (without multiple parton interactions) produces

too few particles in the direction opposite of PTmaxT!



““Associated” PTsum DensityAssociated” PTsum DensityPYTHIA Tune A vs HERWIGPYTHIA Tune A vs HERWIG


0.1

1.0

10.0

0 30 60 90 120 150 180 210 240 270 300 330 360

(degrees)

As

so

cia

ted

PT

su

m D

en

sit

y (

Ge

V/c

)

PTmaxT > 2.0 GeV/c

PY Tune ABack-to-Back

30 < ET(jet#1) < 70 GeV




PTmaxT not included


0.1

1.0

10.0

0 30 60 90 120 150 180 210 240 270 300 330 360

(degrees)

As

so

cia

ted

PT

su

m D

en

sit

y (

Ge

V/c

)

PTmaxT > 2.0 GeV/c

HERWIGBack-to-Back

30 < ET(jet#1) < 70 GeV




PTmaxT not included


-2.0

-1.0

0.0

1.0

2.0

0 30 60 90 120 150 180 210 240 270 300 330 360

(degrees)

Da

ta -

Th

eo

ry




PYTHIA Tune A




-2

-1

0

1

2

0 30 60 90 120 150 180 210 240 270 300 330 360

(degrees)

Da

ta -

Th

eo

ry



Back-to-Back30 < ET(jet#1) < 70 GeVHERWIG



For PTmaxT > 2.0 GeV both PYTHIA and HERWIG produce

slightly too much “associated” PTsum in the direction of PTmaxT!

But HERWIG (without multiple parton interactions) produces

too few particles in the direction opposite of PTmaxT!

Documents

Min-Bias and the Underlying Event in Run 2