CDF Joint Physics Group June 27, 2003 Rick FieldPage 1 PYTHIA Tune A versus Run 2 Data Compare PYTHIA Tune A with Run 2 data on the “underlying event”

CDF Joint Physics Group June 27, 2003

Rick Field Page 1

PYTHIA Tune A versusPYTHIA Tune A versusRun 2 DataRun 2 Data

Compare PYTHIA Tune A with Run 2 data on the “underlying event”.

Outline of Talk

Compare PYTHIA Tune A with the properties of the “calorimeter jets” as measured in Run 2.

Use PYTHIA Tune A to correct the Run 2 data from measured to “true”.

Proton AntiProton

“Hard” Scattering

PT(hard)

Outgoing Parton

Outgoing Parton

Underlying Event Underlying Event

Initial-State Radiation

Final-State Radiation

Compare PYTHIA Tune A before and after CDFSIM.

Calorimeter Jet Construct “correction factors”!

JetClu R = 0.7


Rick Field Page 2

““Underlying Event”Underlying Event”as defined by “Charged particle Jets”as defined by “Charged particle Jets”

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”

Charged Particle Correlations PT > 0.5 GeV/c || < 1

Toward-side “jet”(always)

Away-side “jet”(sometimes)

Perpendicular to the plane of the 2-to-2 hard scattering

“Transverse” region is very sensitive to the “underlying event”!

-1 +1

2

0

Leading ChgJet

Toward Region

Transverse Region

Transverse Region

Away Region

Away Region

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


Rick Field Page 3

Charged Particle Density

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

dP

T (

1/G

eV/c

)

CDF Run 1data uncorrectedtheory corrected

1.8 TeV ||<1 PT>0.5 GeV/c

CDF Min-Bias

"Transverse"PT(chgjet#1) > 5 GeV/c

"Transverse"PT(chgjet#1) > 30 GeV/c

PYTHIA 6.206 Set A

CTEQ5L

"Transverse" Charged Particle Density: dN/dd

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

"Tra

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erse

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har

ged

Den

sity

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

CDF Run 1data uncorrectedtheory corrected

PYTHIA 6.206 Set A

Tuned PYTHIA 6.206Tuned PYTHIA 6.206Run 1 Tune ARun 1 Tune A

Compares the average “transverse” charge particle density (||<1, PT>0.5 GeV) versus PT(charged jet#1) and the PT distribution of the “transverse” and “Min-Bias” densities with the QCD Monte-Carlo predictions of a tuned version of PYTHIA 6.206 (PT(hard) > 0, CTEQ5L, Set A).

Set A Min-Bias<dNchg/dd> = 0.24

Charged Particle Density: dN/dd

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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

Describes “Min-Bias” collisions! Describes the “underlying event”!

“Min-Bias”

Set A PT(charged jet#1) > 30 GeV/c“Transverse” <dNchg/dd> = 0.60

Describes the rise from “Min-Bias” to “underlying event”!


Rick Field Page 4

Charged Particle Jet #1 Direction

“Toward”


“Away”


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1.25

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PT(charged jet#1) (GeV/c)"T

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CDF Run 1 Min-Bias

CDF Run 1 JET20CDF Run 1 Data

data uncorrected

1.8 TeV ||<1.0 PT>0.5 GeV


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CDF Run 1 Min-Bias

CDF Run 1 JET20

||<1.0 PT>0.5 GeV

CDF Preliminarydata uncorrected

“ “Transverse” Transverse” Charged Particle DensityCharged Particle Density

Shows the data on the average “transverse” charge particle density (||<1, PT>0.5 GeV) as a function of the transverse momentum of the leading charged particle jet from Run 1.

Compares the Run 2 data (Min-Bias, JET20, JET50, JET70, JET100) with Run 1. The errors on the (uncorrected) Run 2 data include both statistical and correlated systematic uncertainties.


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CDF Run 2

“Transverse” region as defined by the leading “charged particle jet”


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CDF Run 2 Preliminary

||<1.0 PT>0.5 GeV/c


Excellent agreement between Run 1 and 2!


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CDF Run 1 Published


PYTHIA Tune A

||<1.0 PT>0.5 GeV/c

CDF Preliminarydata uncorrectedtheory corrected

PYTHIA Tune A was tuned to fit the “underlying event” in Run I!

Shows the prediction of PYTHIA Tune A at 1.96 TeV after detector simulation (i.e. after CDFSIM).


Rick Field Page 5

“ “Transverse” Transverse” Charged PTsum DensityCharged PTsum Density

Shows the data on the average “transverse” charged PTsum density (||<1, PT>0.5 GeV) as a function of the transverse momentum of the leading charged particle jet from Run 1.

"Transverse" Charged PTsum Density: dPTsum/dd

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ran

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PT

sum

Den

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(G

eV) CDF JET20

CDF Min-BiasCDF Run 1 Data

data uncorrected

1.8 TeV ||<1.0 PT>0.5 GeV



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PT

sum

Den

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(G

eV)

CDF JET20

CDF Min-Bias


||<1.0 PT>0.5 GeV

Charged Particle Jet #1 Direction

“Toward”


“Away”


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1.25

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150


ran

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PT

sum

Den

sity

(G

eV)

CDF Run 2

“Transverse” region as defined by the leading “charged particle jet”


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PT

sum

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(G

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CDF Run 1 Published



||<1.0 PT>0.5 GeV/c



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ran

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PT

sum

Den

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(G

eV/c

)

CDF Run 1 Published


PYTHIA Tune A


||<1.0 PT>0.5 GeV/c

Shows the prediction of PYTHIA Tune A at 1.96 TeV after detector simulation (i.e. after CDFSIM).

PYTHIA Tune A was tuned to fit the “underlying event” in Run I!


Rick Field Page 6

JetClu Jet #1 Direction


“Toward”

“Away”

“Toward-Side” Jet

“Away-Side” Jet

““Underlying Event”Underlying Event”as defined by “Calorimeter Jets”as defined by “Calorimeter Jets”

Look at charged particle correlations in the azimuthal angle relative to the leading JetClu jet.

Define || < 60o as “Toward”, 60o < || < 120o as “Transverse”, and || > 120o as “Away”. All three regions have the same size in - space, x = 2x120o = 4/3.

Charged Particle Correlations PT > 0.5 GeV/c || < 1

Away-side “jet”(sometimes)

Perpendicular to the plane of the 2-to-2 hard scattering

“Transverse” region is very sensitive to the “underlying event”!


“Toward”


“Away”

-1 +1

2

0

Leading Jet

Toward Region

Transverse Region

Transverse Region

Away Region

Away Region

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


Rick Field Page 7

““Transverse” Transverse” Charged Particle DensityCharged Particle Density

Shows the data on the average “transverse” charge particle density (||<1, PT>0.5 GeV) as a function of the transverse energy of the leading JetClu jet (R = 0.7, |(jet)| < 2) from Run 2.


“Toward”


“Away”

Compares the “transverse” region of the leading “charged particle jet”, chgjet#1, with the “transverse” region of the leading “calorimeter jet” (JetClu R = 0.7), jet#1.

JetClu Jet #1 or ChgJet#1

Direction

“Toward”


“Away”

, compared with PYTHIA Tune A after CDFSIM.


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ET(jet#1) (GeV)

"Tra

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erse

" C

har

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Den

sity


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

JetClu (R = 0.7, |(jet#1)| < 2)

“Transverse” region as defined by the leading

“calorimeter jet” "Transverse" Charged Particle Density: dN/dd

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0 25 50 75 100 125 150 175 200 225 250

ET(jet#1) (GeV)

"Tra

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" C

har

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Den

sity

PYTHIA Tune A

CDF Run 2 PreliminaryCDF Preliminary

data uncorrectedtheory corrected


JetClu (R = 0.7, |(jet#1)| < 2)


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PT(chgjet#1) or ET(jet#1) (GeV)

"Tra

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har

ged

Den

sity CDF Preliminary

data uncorrected


ChgJet#1 R = 0.7

JetClu Jet#1 (R = 0.7,|(jet)|<2)


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"Tra

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ChgJet#1 R = 0.7

JetClu Jet#1 (R = 0.7, |(jet)|<2)

PYTHIA Tune A 1.96 TeV


Rick Field Page 8

““Transverse” Transverse” Charged PTsum DensityCharged PTsum Density

Shows the data on the average “transverse” charged PTsum density (||<1, PT>0.5 GeV) as a function of the transverse energy of the leading JetClu jet (R = 0.7, |(jet)| < 2) from Run 2.


“Toward”


“Away”

Compares the “transverse” region of the leading “charged particle jet”, chgjet#1, with the “transverse” region of the leading “calorimeter jet” (JetClu R = 0.7), jet#1.

JetClu Jet #1 or ChgJet#1

Direction

“Toward”


“Away”



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0.5

1.0

1.5

0 25 50 75 100 125 150 175 200 225 250

ET(jet#1) (GeV)

"Tra

nsv

erse

" P

Tsu

m D

ensi

ty (

GeV

/c)



JetClu (R = 0.7, |(jet#1)| < 2)


“calorimeter jet” "Transverse" Charged PTsum Density: dPTsum/dd

0.0

0.5

1.0

1.5

0 25 50 75 100 125 150 175 200 225 250

ET(jet#1) (GeV)

"Tra

nsv

erse

" P

Tsu

m D

ensi

ty (

GeV

/c)

PYTHIA Tune A




JetClu (R = 0.7, |(jet#1)| < 2)


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0.5

1.0

1.5

0 25 50 75 100 125 150 175 200 225 250


"Tra

nsv

erse

" P

Tsu

m D

ensi

ty (

GeV

/c)


Charged Particles (||<1.0, PT>0.5 GeV/c) ChgJet#1 R = 0.7



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0.5

1.0

1.5

0 25 50 75 100 125 150 175 200 225 250


"Tra

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" P

Tsu

m D

ensi

ty (

GeV

/c)


Charged Particles (||<1.0, PT>0.5 GeV/c) ChgJet#1 R = 0.7




Rick Field Page 9

““Transverse” Transverse” Charged Particle DensityCharged Particle Density

Shows the data on the average “transverse” charge particle density (||<1, PT>0.5 GeV) as a function of the transverse energy of the leading JetClu jet (R = 0.7, |(jet)| < 2) from Run 2.


“Toward”


“Away”

Shows the generated prediction of PYTHIA Tune A before CDFSIM.



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JetClu (R = 0.7, |(jet#1)| < 2)


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PYTHIA Tune A

CDF Run 2 PreliminaryCDF Preliminary

data uncorrectedtheory corrected


JetClu (R = 0.7, |(jet#1)| < 2)


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PY Tune A Generated

PY Tune A Corrected




JetClu (R = 0.7, |(jet#1)| < 2)


“calorimeter jet”

CDFSIM/Generated: "Transverse" dN/dd

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 25 50 75 100 125 150 175 200 225 250

ET(jet#1) (GeV)

CD

FS

IM/G

ener

ated

JetClu (R = 0.7, |(jet#1)| < 2)



Shows the ratio CDFSIM/Generated for PYTHIA Tune A.

Small correction (about 10%) independent of ET(jet#1)!


Rick Field Page 10

The Leading The Leading “Charged Particle” Jet“Charged Particle” Jet

Shows the data on the average number of charged particles within the leading “charged particle jet” (||<1, PT>0.5 GeV, R = 0.7) as a function of the transverse momentum of the leading “charged particle jet” from Run 1.

Nchg(chgjet#1) versus PT(chgjet#1)

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Ave

rave

Nch

g

CDF Run 1 Min-Bias

CDF Run 1 JET20

CDF Run 1 Datadata uncorrected

1.8 TeV ||<1.0 PT>0.5 GeV R = 0.7


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CDF Run 1 Min-Bias

CDF Run 1 JET20


||<1.0 PT>0.5 GeV R = 0.7



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CDF Run 2


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CDF Run 1 Min-Bias

CDF Run 1 JET20

CDF Run 2


||<1.0 PT>0.5 GeV/c R = 0.7


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CDF Run 1 Min-Bias

CDF Run 1 JET20

CDF Run 2

PY Tune A

||<1.0 PT>0.5 GeV/c R = 0.7



PYTHIA produces too many charged particles in the leading

“charged particle jet”!


Rick Field Page 11

The Leading The Leading “Calorimeter” Jet“Calorimeter” Jet

Shows the Run 2 data on the average number of charged particles (||<1, PT>0.5 GeV, R = 0.7) within the leading “calorimeter jet” (JetClu R = 0.7, |(jet)|< 0.7) as a function of the transverse energy of the leading “calorimeter jet”.

Compares the number of charged particles within the leading “charged particle jet”, chgjet#1, with the number of charged particles within the leading “calorimeter jet” (JetClu R = 0.7), jet#1.

Nchg(jet#1) versus ET(jet#1)

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ET(jet#1) (GeV)

Ave

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Nch

gCharged Particles (||<1.0, PT>0.5 GeV/c) JetClu R = 0.7 |(jet)| < 0.7



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0 25 50 75 100 125 150 175 200 225 250

ET(jet#1) (GeV)

Ave

rave

Nch




PYTHIA produces too many charged particles in the

leading “calorimeter jet”!

Nchg(jet#1) and Nchg(charged jet#1)

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ET(jet#1) or PT(charged jet#1) (GeV)

Ave

rave

Nch



Nchg(jet#1)

Nchg(chgjet#1)

Nchg(jet#1) and Nchg(charged jet#1)

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Ave

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Nch




Nchg(jet#1)

Nchg(chgjet#1)


Rick Field Page 12

The Leading “Calorimeter” JetThe Leading “Calorimeter” JetCharged Particle MultiplicityCharged Particle Multiplicity

Shows the Run 2 data on the average number of charged particles (||<1, PT>0.5 GeV, R = 0.7) within the leading “calorimeter jet” (JetClu R = 0.7, |(jet)|< 0.7) as a function of ET(jet#1) compared with PYTHIA Tune A after CDFSIM.


Calorimeter Jet CDFSIM/Generated: Leading Jet Nchg

20%

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80%

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100%

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ET(jet#1) (GeV)

CD

FS

IM/G

ener

ated

PYTHIA Tune A 1.96 TeV JetClu R = 0.7 |(jet)| < 0.7



Correction becomes large for ET(jet#1) > 100 GeV and

depends on ET(jet#1)!

Shows “corrected” Run 2 data compared with PYTHIA Tune A (uncorrected).


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ET(jet#1) (GeV)A

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ve N

chg

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ET(jet#1) (GeV)A

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PY Tune A Generated

PY Tune A + CDFSIM

CDF Run 2 Uncorrected Charged Particles (||<1.0, PT>0.5 GeV/c)

JetClu R = 0.7 |(jet)| < 0.7



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ET(jet#1) (GeV)A

vera

ve N

chg


JetClu R = 0.7 |(jet)| < 0.7

CDF Preliminarydata corrected

theory uncorrected


Multiply data by the “unfolding function” (i.e. Generated/CDFSIM) determined from PYTHIA Tune A to get “corrected” data.


Rick Field Page 13

The Leading “Calorimeter” JetThe Leading “Calorimeter” JetCharged PCharged PTT Distribution Distribution

Shows the transverse momentum distribution of charged particles (||<1) within the leading “charged particle jet” compared with PYTHIA Tune A. The plot shows dNchg/dz with z = PT/PT(chgjet#1) for the range 30 < PT(chgjet#1) < 70 GeV/c.

Shows the transverse momentum distribution of charged particles (||<1) within the leading “calorimeter jet” (JetClu, R = 0.7, |(jet)| < 0.7) compared with PYTHIA Tune A. The plot shows dNchg/dz with z = PT/ET(jet#1) for the range 30 < ET(jet#1) < 70 GeV.

PYTHIA produces too many “soft” charged particles within

the leading “jet”!

The integral of F(z) is the average number of charged particles within the

leading “charged particle jet”.

Leading Charged Particle Jet

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1.0

10.0

100.0

0.0 0.2 0.4 0.6 0.8 1.0

z = PT/PT(chgjet#1)

F(z

) =

dN

/dz


R = 0.7 30 < PT(chgjet#1) < 70 GeV

||<1.0 PT>0.5 GeV/c


Leading Calorimeter Jet

1.0E-03

1.0E-02

1.0E-01

1.0E+00

1.0E+01

1.0E+02

0.0 0.2 0.4 0.6 0.8 1.0 1.2

z = PT/ET(Jet#1)

F(z

) =

dN

/dz


JetClu R = 0.7 30 < ET(jet#1) < 70 GeV



PYTHIA produces too many “soft” charged particles within

the leading “jet”!


Rick Field Page 14

The Leading “Calorimeter” JetThe Leading “Calorimeter” JetCharged PTCharged PTsumsum & PT & PTmaxmax Fraction Fraction

Shows average charged PTsum fraction, PTsum/ET(jet#1), and the average charged PTmax fraction, PTmax/ET(jet#1), within the leading “calorimeter jet” (JetClu, R = 0.7, |(jet)| < 0.7) compared with PYTHIA Tune A.

Shows distribution of the charged PTsum fraction, z = PTsum/ET(jet#1), and the distribution of charged PTmax fraction, z = PTmax/ET(jet#1), within the leading “calorimeter jet” (JetClu, R = 0.7, |(jet)| < 0.7) for the range 95 < ET(jet#1) < 130 GeV compared with PYTHIA Tune A.

Charged Fraction within the Leading Jet

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z = PTmax/ET(jet#1) or PTsum/ET(jet#1)

(1/N

) d

N/d

z


JetClu R = 0.7 95 < ET(jet#1) < 130 GeV



PTmax/ET(jet#1)

PTsum/ET(jet#1)

PYTHIA does okay on the charged PTmax fraction!PYTHIA does okay on the charged PTmax fraction!

But PYTHIA does not do well on the charged PTsum fraction!

But PYTHIA does not do as well on the charged PTsum fraction!

PTsum/ET(Jet#1) and PTmax/ET(jet#1)

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ET(jet#1) (GeV)

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ion

JetClu R = 0.7 |(jet)| < 0.7




PTsum(chg)/ET(jet#1)

PTmax(chg)/ET(jet#1)


Rick Field Page 15

The Leading “Calorimeter” JetThe Leading “Calorimeter” JetCharged PTCharged PTsumsum Fraction Fraction

Shows average charged PTsum fraction, PTsum/ET(jet#1), within the leading “calorimeter jet” (JetClu, R = 0.7, |(jet)| < 0.7) compared with PYTHIA Tune A after CDFSIM.

Calorimeter Jet


CDFSIM/Generated: Leading Jet PTsum Fraction

20%

30%

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50%

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70%

80%

90%

100%

0 25 50 75 100 125 150 175 200 225 250

ET(jet#1) (GeV)

CD

FS

IM/G

ener

ated



JetClu R = 0.7 |(jet)| < 0.7


Very large correction that depends on ET(jet#1)!

Shows “corrected” Run 2 data compared with PYTHIA Tune A (uncorrected).

Leading Jet: Charged PTsum/ET(Jet#1)

0.2

0.3

0.4

0.5

0.6

0.7

0 25 50 75 100 125 150 175 200 225 250

ET(jet#1) (GeV)C

har

ged

PT

sum

/ET

(jet

#1)

JetClu R = 0.7 |(jet)| < 0.7




Leading Jet: Charged PTsum/ET(jet#1)

0.2

0.3

0.4

0.5

0.6

0.7

0 25 50 75 100 125 150 175 200 225 250

ET(jet#1) (GeV)C

har

ged

PT

sum

/ET

(jet

#1)

PY Tune A Generated

PY Tune A + CDFSIM

CDF Run 2 Uncorrected

JetClu R = 0.7 |(jet)| < 0.7CDF Preliminarydata uncorrected


Leading Jet: Charged PTsum/ET(jet#1)

0.2

0.3

0.4

0.5

0.6

0.7

0 25 50 75 100 125 150 175 200 225 250

ET(jet#1) (GeV)C

har

ged

PT

sum

/ET

(jet

#1)

JetClu R = 0.7 |(jet)| < 0.7CDF Preliminary

data correctedtheory uncorrected



Multiply data by the “unfolding function” (i.e. Generated/CDFSIM) determined from PYTHIA Tune A to get “corrected” data.


Rick Field Page 16

Proton-AntiProtonProton-AntiProtonCollisionsCollisions

Draw an R = 0.7 cone around the leading calorimeter jet (JetClu, R = 0.7).

Proton AntiProton

Proton AntiProton

Jet Direction

R

ETjet

Proton AntiProton

Jet Direction

R

ETjet

PT

KT

Charged Particle

Look at charged particles within R = 0.7 of the leading calorimeter jet.

Momentum perpendicular to

the jet axis

Momentum perpendicular to

the beam axis


Rick Field Page 17

The Leading “Calorimeter” JetThe Leading “Calorimeter” JetCharged KCharged KTT Distribution Distribution

Shows the average momentum perpendicular to the jet axis for charged particles (PT > 0.5 GeV/c, ||<1) within the leading “calorimeter jet” (JetClu, R = 0.7) compared with PYTHIA Tune A.

Shows the distribution of momentum perpendicular to the jet axis for charged particles within the leading “calorimeter jet” compared with PYTHIA Tune A. The plot shows dNchg/dKT for the range 30 < ET(jet#1) < 70 GeV and 95 < ET(jet#1) < 130 GeV.

Jet#1 <KT> versus ET(jet#1)

0.0

0.4

0.8

1.2

1.6

0 25 50 75 100 125 150 175 200 225 250

ET(jet#1) (GeV)

Av

erav

e K

T (

Ge

V/c

)

CDF Run 2

PY Tune A

JetClu R = 0.7 0.1 < |DET| < 0.7

CDF Preliminarydata uncorrectedtheory + CDFSIM

Perpendicular to Jet Axis

1.96 TeV

KT Distribution within Jet#1

1.0E-05

1.0E-04

1.0E-03

1.0E-02

1.0E-01

1.0E+00

1.0E+01

0 2 4 6 8 10 12 14 16 18 20

KT (GeV/c)

dN

/dK

T (

1/G

eV

/c)

Perpendicular to Jet Axis


JetClu R = 0.7 0.1 < |DET| < 0.7

30 < ET(jet1) < 70 GeV

95 < ET(jet1) < 130 GeV

1.96 TeV

Increases as ET(jet#1) increases!


Rick Field Page 18

Inclusive Inclusive Jet Cross SectionJet Cross Section

Shows the uncorrected inclusive “calorimeter jet” cross-section for (JetClu, R = 0.7, energy scale factor of 1.042) compared with PYTHIA Tune A (after CDFSIM).

Inclusive Jet Cross Section

1.0E-07

1.0E-06

1.0E-05

1.0E-04

1.0E-03

1.0E-02

1.0E-01

1.0E+00

1.0E+01

1.0E+02

1.0E+03

0 25 50 75 100 125 150 175 200 225 250

ET(jet) (GeV)

ds /

dE

T (m b

/Ge

V) CDF Run2 AllJets

PY Tune A


JetClu R = 0.7 0.1 < |DET| < 0.7

1.96 TeV

Inclusive Jet Cross Section: Data/Theory

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

0 25 50 75 100 125 150 175 200 225 250

ET(jet) (GeV)

Ra

tio

: D

ata

/Th

eo

ry

JetClu R = 0.7 0.1 < |DET| < 0.7


PY Tune A + CDFSIM

1.96 TeV

Shows the ratio of the uncorrected inclusive “calorimeter jet” cross-section for (JetClu, R = 0.7, energy scale factor of 1.042) to PYTHIA Tune A (after CDFSIM).

Very similar to Frank Chlebana’s

“corrected” plots!

Data and theory are normalized to agree at this one point. This fixes the normalization for

all the other plots presented in this talk!


Rick Field Page 19

Inclusive Cross-SectionInclusive Cross-Section“Correction Factors”“Correction Factors”

Shows PYTHIA Tune A + CDFSIM inclusive “calorimeter jet” cross-section for (JetClu, R = 0.7) compared with the “true” cross-section where “true” is the PTsum of all hadrons (partons) with PT > 0 in R = 0.7 cone around JetClu.

Inclusive Cross-Section: ds/dET

1.0E-07

1.0E-06

1.0E-05

1.0E-04

1.0E-03

1.0E-02

1.0E-01

1.0E+00

1.0E+01

1.0E+02

1.0E+03

0 25 50 75 100 125 150 175 200 225 250

ET (GeV)

ds /

dE

T (m b

/Ge

V)

ET(particles in R)

ET(partons in R)

ET(jetclu)


0.1<|DET|<0.7

R = 0.7

Inclusive X-Sec Ratio: (PTsum in R=0.7)/ET(jetclu)

0.5

1.0

1.5

2.0

2.5

3.0

0 25 50 75 100 125 150 175 200 225 250

ET(jetclu) (GeV)

Cro

ss

-Se

cti

on

Ra

tio

PYTHIA Tune A 1.96 teV

0.1<|DET|<0.7

Particles

Partons

Measured

“True”

Correction factors!

ETsum(in R)/ET(jet#1) vs ET(jet#1)

0.8

0.9

1.0

1.1

1.2

1.3

0 25 50 75 100 125 150 175 200 225 250

ET(jet#1) (GeV)

ETs

um

(in

R)/

ET

(je

t)


0.1<|DET|<0.7

Particles

Partons

JetClu R = 0.7

“True”


Rick Field Page 20

Jet Cross SectionsJet Cross Sections

Shows the Run 2 uncorrected inclusive “calorimeter jet” cross-section and the leading “calorimeter jet” cross-section (JetClu, R = 0.7, energy scale factor of 1.042).

Shows the ratio of the leading jet cross section to the inclusive jet cross-section for (JetClu, R = 0.7, energy scale factor of 1.042) compared with PYTHIA Tune A (after CDFSIM).

Jet Cross Sections

1.0E-07

1.0E-06

1.0E-05

1.0E-04

1.0E-03

1.0E-02

1.0E-01

1.0E+00

1.0E+01

1.0E+02

1.0E+03

0 25 50 75 100 125 150 175 200 225 250

ET(jet) (GeV)

ds /

dE

T (m b

/Ge

V) CDF Run2 AllJets

CDF Run2 Jet1


JetClu R = 0.7 0.1 < |DET| < 0.7

1.96 TeV

Jet Cross-Section Ratio: Jet#1/AllJets

0.5

0.6

0.7

0.8

0.9

1.0

0 25 50 75 100 125 150 175 200 225 250

ET(jet) (GeV)

Jet#

1/A

llJet

s

CDF Run 2

PY Tune A

JetClu R = 0.7 0.1 < |DET| < 0.7


1.96 TeV

Measures how much cross-section comes

from >1 jet!


Rick Field Page 21

Jet Cross SectionsJet Cross Sections

Shows the uncorrected inclusive jet cross-section for (JetClu, R = 0.7, energy scale factor of 1.042) compared with PYTHIA Tune A (after CDFSIM).

Shows the ratio of the uncorrected inclusive jet cross-section for (JetClu, R = 0.7, energy scale factor of 1.042) to PYTHIA Tune A (after CDFSIM).

Jet Cross Sections

1.0E-09

1.0E-08

1.0E-07

1.0E-06

1.0E-05

1.0E-04

1.0E-03

1.0E-02

1.0E-01

1.0E+00

1.0E+01

1.0E+02

1.0E+03

0 25 50 75 100 125 150 175 200 225 250

ET(jet) (GeV)

ds /

dE

T

(mb

/Ge

V)


JetClu R = 0.7 0.1 < |DET| < 0.7

Jet#1

Jet#2Jet#3

1.96 TeV

Jet Cross-Sections: Data/Theory

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

0 25 50 75 100 125 150 175 200 225 250

ET(jet) (GeV)

Ra

tio

: D

ata

/Th

eo

ry

Jet#1

Jet#2

Jet#3

JetClu R = 0.7 0.1 < |DET| < 0.7


PY Tune A + CDFSIM

1.96 TeV

PThat/ET(jet#1) vs ET(jet#1)

0.7

0.8

0.9

1.0

1.1

1.2

1.3

0 25 50 75 100 125 150 175 200 225 250

ET(jet#1) (GeV)

PT

ha

t/E

T(j

et#

1)


0.1<|DET|<0.7

JetClu R = 0.7

Tansverse momentum of the hard 2-to-2 parton-parton collision!


Rick Field Page 22

Leading “Charged Particle Jet” Leading “Charged Particle Jet” Cross SectionCross Section

Shows the uncorrected leading “charged particle jet” cross-section for (PT > 0.5 GeV/c, ||<1) compared with PYTHIA Tune A (after CDFSIM).

Shows the ratio of the uncorrected leading “charged particle jet” cross-section for (PT > 0.5 GeV/c, ||<1) to PYTHIA Tune A (after CDFSIM).

Leading ChgJet Cross Section

1.0E-06

1.0E-05

1.0E-04

1.0E-03

1.0E-02

1.0E-01

1.0E+00

1.0E+01

1.0E+02

1.0E+03

1.0E+04

0 25 50 75 100 125 150


ds /

dP

T (m b

/Ge

V) PY Tune A

CDF Run2


1.96 TeV ||<1.0 PT>0.5 GeV R = 0.7

Leading ChgJet Cross Section: Data/Theory

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

0 25 50 75 100 125 150

PT(charged jet#1) (GeV)

Ra

tio

: D

ata

/Th

eo

ry

PT > 0.5 GeV/c || < 0.7 R = 0.7


PY Tune A + CDFSIM

1.96 TeV

Jet Cross-Sections: Data/Theory

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

0 25 50 75 100 125 150 175 200 225 250


Ra

tio

: D

ata

/Th

eo

ry

Charged Particle Jet#1

Calorimeter Jet#1


PY Tune A + CDFSIM

Compares data/theory for the leading charged particle jet and the

leading calorimeter jet!


Rick Field Page 23

Summary & ConclusionsSummary & Conclusions

PYTHIA Tune A

PYTHIA Tune A does a good job of describing the “underlying event” in the Run 2 data as defined by “charged particle jets” and as defined by “calorimeter jets”. HERWIG Run 2 comparisons will be coming soon!

PYTHIA Tune A does a fairly good job (although not perfect) describing the properties of the “calorimeter jets” in Run 2 (in the central region!).

I am hoping we can use the QCD Monte-Carlo models (PYTHIA & HERWIG) to correct the data from measured to “true” by constructing “correction factors” for every observable of interest.

Proton AntiProton

PT(hard)

Outgoing Parton

Outgoing Parton

Underlying Event Underlying Event

Initial-State Radiation

Final-State Radiation

This is a different method from the “jet energy corrections” used in Run 1!

Documents

CDF Joint Physics Group June 27, 2003 Rick FieldPage 1 PYTHIA Tune A versus Run 2 Data Compare PYTHIA Tune A with Run 2 data on the “underlying event”