Fermilab Energy Scaling Workshop April 29, 2009 Rick Field – Florida/CDF/CMSPage 1 1 st Workshop...

Fermilab Energy Scaling Workshop April 29, 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

Extrapolating “min-bias” collisions to the LHC.

LHC predictions!

Studying <pT> versus Nchg in “min-bias” collisions and in Drell-Yan.

From CDF to CMSFermilab 2009

Summary.



Charged Particle Density: dN/dCharged Particle Density: dN/dCharged Particle Density: dN/d

0.0

1.0

2.0

3.0

4.0

5.0

-8 -6 -4 -2 0 2 4 6 8

PseudoRapidity

Ch

arg

ed

Par

ticl

e D

en

sit

y

Min-Bias1.96 TeV

PY Tune A

PY64 Tune P329

RDF Preliminarygenerator level

PY64 Tune S320

Charged Particles (all PT)

Charged Particle Density: dN/d

0.0

0.5

1.0

1.5

2.0

-8 -6 -4 -2 0 2 4 6 8

PseudoRapidity

Ch

arg

ed

Par

ticl

e D

en

sit

y


Charged Particles (PT>0.5 GeV/c)

Min-Bias1.96 TeV

PY64 Tune P329

PY Tune A

PY64 Tune S320

Charged particle (all pT) pseudo-rapidity distribution, dNchg/dd, at 1.96 TeV for inelastic non-diffractive collisions from PYTHIA Tune A, Tune S320, and Tune P324.

Charged particle (pT>0.5 GeV/c) pseudo-rapidity distribution, dNchg/dd, at 1.96 TeV for inelastic non-diffractive collisions from PYTHIA Tune A, Tune S320, and Tune P324.



Charged Particle Density: dN/dCharged Particle Density: dN/d

Proton AntiProton

“Minumum Bias” Collisions

Tevatron LHC

Extrapolations of PYTHIA Tune A, Tune S320, and Tune P329 to the LHC.


0.0

1.0

2.0

3.0

4.0

5.0

-8 -6 -4 -2 0 2 4 6 8

PseudoRapidity

Ch

arg

ed

Part

icle

De

ns

ity

Min-Bias1.96 TeV

PY Tune A

PY64 Tune P329


PY64 Tune S320

Charged Particles (all PT)


0.0

2.0

4.0

6.0

8.0

-8 -6 -4 -2 0 2 4 6 8

PseudoRapidity

Ch

arg

ed

Pa

rtic

le D

en

sit

y


Charged Particles (all PT) Min-Bias14 TeV

PY Tune A

PY64 Tune P329

PY64 Tune S320

Charged particle (all pT) pseudo-rapidity distribution, dNchg/dd, at 1.96 TeV for inelastic non-diffractive collisions from PYTHIA Tune A, Tune S320, and Tune P324.

Proton Proton


RDF LHC Prediction!



Charged Particle Density: dN/dCharged Particle Density: dN/d

Proton AntiProton


Tevatron LHC

Extrapolations of PYTHIA Tune A, Tune S320, and Tune P329 to the LHC.

Charged particle (pT > 0.5 GeV/c) pseudo-rapidity distribution, dNchg/dd, at 1.96 TeV for inelastic non-diffractive collisions from PYTHIA Tune A, Tune S320, and Tune P324.

Proton Proton



0.0

0.5

1.0

1.5

2.0

-8 -6 -4 -2 0 2 4 6 8

PseudoRapidity

Ch

arg

ed

Part

icle

De

ns

ity


Charged Particles (PT>0.5 GeV/c)

Min-Bias1.96 TeV

PY64 Tune P329

PY Tune A

PY64 Tune S320


0.0

1.0

2.0

3.0

4.0

-8 -6 -4 -2 0 2 4 6 8

PseudoRapidity

Ch

arg

ed

Pa

rtic

le D

en

sit

y


Charged Particles (PT>0.5 GeV/c) Min-Bias14 TeV

PY64 Tune P329

PY Tune A

PY64 Tune S320

RDF LHC Prediction!


0.0

1.0

2.0

3.0

4.0

-8 -6 -4 -2 0 2 4 6 8

PseudoRapidity

Ch

arg

ed

Pa

rtic

le D

en

sity



PY64 Tune P329

PY Tune A

PY64 Tune S320

PY Tune DWT

Why is py64 Tune P329 higher than py Tune DWT??



Min-Bias CorrelationsMin-Bias Correlations

Data at 1.96 TeV on the average pT of charged particles versus the number of charged particles (pT > 0.4 GeV/c, || < 1) for “min-bias” collisions at CDF Run 2. The data are corrected to the particle level and are compared with PYTHIA Tune A at the particle level (i.e. generator level).

Proton AntiProton


Average PT versus Nchg

0.6

0.8

1.0

1.2

1.4

0 10 20 30 40 50

Number of Charged Particles

Ave

rag

e P

T (

GeV

/c)

CDF Run 2 Preliminarydata corrected

generator level theory

Charged Particles (||<1.0, PT>0.4 GeV/c)

Min-Bias1.96 TeV

ATLAS

pyA

pyDW



Min-Bias: Average PT versus NchgMin-Bias: Average PT versus Nchg

Proton AntiProton

“Soft” Hard Core (no hard scattering)

Proton AntiProton

PT(hard)

Outgoing Parton

Outgoing Parton




“Hard” Hard Core (hard scattering)

CDF “Min-Bias”

= +


0.6

0.8

1.0

1.2

1.4

0 5 10 15 20 25 30 35 40


Ave

rag

e P

T (

GeV

/c)




Min-Bias1.96 TeV

pyAnoMPI

ATLAS

pyA

Proton AntiProton

Multiple-Parton Interactions

PT(hard)

Outgoing Parton

Outgoing Parton




+

Beam-beam remnants (i.e. soft hard core) produces low multiplicity and small <pT> with <pT> independent of the multiplicity.

Hard scattering (with no MPI) produces large multiplicity and large <pT>.

Hard scattering (with MPI) produces large multiplicity and medium <pT>.

The CDF “min-bias” trigger picks up most of the “hard

core” component!

This observable is sensitive to the MPI tuning!



Average PT versus NchgAverage PT versus Nchg

Proton AntiProton


Proton AntiProton

Drell-Yan Production

Anti-Lepton

Lepton


Data at 1.96 TeV on the average pT of charged particles versus the number of charged particles (pT > 0.4 GeV/c, || < 1) for “min-bias” collisions at CDF Run 2. The data are corrected to the particle leveland are compared with PYTHIA Tune A, Tune DW, and the ATLAS tune at the particle level (i.e. generator level).

Particle level predictions for the average pT of charged particles versus the number of charged particles (pT > 0.5 GeV/c, || < 1, excluding the lepton-pair) for for Drell-Yan production (70 < M(pair) < 110 GeV) at CDF Run 2.


0.5

1.0

1.5

2.0

2.5

0 5 10 15 20 25 30 35


Ave

rag

e P

T (

GeV

/c)

CDF Run 2 Preliminarygenerator level theory

"Drell-Yan Production"70 < M(pair) < 110 GeV

Charged Particles (||<1.0, PT>0.5 GeV/c)excluding the lepton-pair

HW

JIM

pyAW

ATLAS


0.5

1.0

1.5

2.0

2.5

0 5 10 15 20 25 30 35


Ave

rag

e P

T (

GeV

/c)





HW

JIM

pyAW

ATLAS


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0.8

1.0

1.2

1.4

0 5 10 15 20 25 30 35 40


Ave

rag

e P

T (

GeV

/c)




Min-Bias1.96 TeV

pyAnoMPI

ATLAS

pyA




Proton AntiProton

Drell-Yan Production (no MPI)

Anti-Lepton

Lepton



0.5

1.0

1.5

2.0

2.5

0 5 10 15 20 25 30 35


Ave

rag

e P

T (

GeV

/c)





HW

JIM

pyAW

ATLAS

Proton AntiProton

Drell-Yan Production (with MPI)

Anti-Lepton

Lepton


Drell-Yan

Proton AntiProton

High PT Z-Boson Production

Z-boson

Outgoing Parton

Initial-State Radiation Final-State Radiation

= +

Z-boson production (with low pT(Z) and no MPI) produces low multiplicity and small <pT>.

+

High pT Z-boson production produces large multiplicity and high <pT>.

Z-boson production (with MPI) produces large multiplicity and medium <pT>.

No MPI!



Average PT(Z) versus NchgAverage PT(Z) versus Nchg

Proton AntiProton


Anti-Lepton

Lepton


Data on the average pT of charged particles versus the number of charged particles (pT > 0.5 GeV/c, || < 1, excluding the lepton-pair) for for Drell-Yan production (70 < M(pair) < 110 GeV) at CDF Run 2. The data are corrected to the particle level and are compared with various Monte-Carlo tunes at the particle level ( i.e. generator level).


0.5

1.0

1.5

2.0

2.5

0 5 10 15 20 25 30 35


Ave

rag

e P

T (

GeV

/c)





HW

JIM

pyAW

ATLAS

PT(Z-Boson) versus Nchg

0

20

40

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80

0 5 10 15 20 25 30 35 40


Ave

rag

e P

T(Z

) (G

eV

/c)




pyAW

HW

JIM

ATLAS

No MPI!

Predictions for the average PT(Z-Boson) versus the number of charged particles (pT > 0.5 GeV/c, || < 1, excluding the lepton-pair) for for Drell-Yan production (70 < M(pair) < 110 GeV) at CDF Run 2.

PT(Z-Boson) versus Nchg

0

20

40

60

80

0 5 10 15 20 25 30 35 40


Ave

rag

e P

T(Z

) (G

eV/c

)





pyAW

HW

JIM

ATLAS

Proton AntiProton

High PT Z-Boson Production

Z-boson

Outgoing Parton





Proton AntiProton


Anti-Lepton

Lepton


Predictions for the average pT of charged particles versus the number of charged particles (pT > 0.5 GeV/c, || < 1, excluding the lepton-pair) for for Drell-Yan production (70 < M(pair) < 110 GeV, PT(pair) < 10 GeV/c) at CDF Run 2.

Average Charged PT versus Nchg

0.6

0.8

1.0

1.2

1.4

0 5 10 15 20 25 30 35


Ave

rag

e P

T (

GeV

/c)



PT(Z) < 10 GeV/c


HW

pyAW


0.6

0.8

1.0

1.2

1.4

0 5 10 15 20 25 30 35


Ave

rag

e P

T (

GeV

/c)



PT(Z) < 10 GeV/c


HW

JIM

ATLAS

pyAW


0.6

0.8

1.0

1.2

1.4

0 5 10 15 20 25 30 35


Ave

rag

e P

T (

GeV

/c)




PT(Z) < 10 GeV/c


HW

JIM

ATLAS

pyAW

Data the average pT of charged particles versus the number of charged particles (pT > 0.5 GeV/c, || < 1, excluding the lepton-pair) for for Drell-Yan production (70 < M(pair) < 110 GeV, PT(pair) < 10 GeV/c) at CDF Run 2. The data are corrected to the particle level and are compared with various Monte-Carlo tunes at the particle level (i.e. generator level).

PT(Z) < 10 GeV/c

No MPI!


0.6

0.8

1.0

1.2

1.4

0 10 20 30 40


Ave

rag

e P

T (

Ge

V/c

)



Charged Particles (||<1.0)pyA

Min-Bias PT > 0.4 GeV/c

Drell-Yan PT > 0.5 GeV PT(Z) < 10 GeV/c

pyAW

Proton AntiProton

“Minumum Bias” Collisions Remarkably similar behavior! Perhaps indicating that MPI playing an important role in

both processes.



LHC PredictionsLHC Predictions

Proton AntiProton


Proton AntiProton

PT(hard)

Outgoing Parton

Outgoing Parton




Proton AntiProton


Anti-Lepton

Lepton



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1.0

2.0

3.0

4.0

-8 -6 -4 -2 0 2 4 6 8

PseudoRapidity

Ch

arg

ed P

arti

cle

Den

sity



PY64 Tune P329

PY Tune A

PY64 Tune S320

"Transverse" Charged Particle Density: dN/dd

0.0

0.4

0.8

1.2

1.6

0 5 10 15 20 25

PTmax (GeV/c)

"Tra

ns

ve

rse

" C

ha

rge

d D

en

sit

y

PY Tune A

Min-Bias14 TeV Charged Particles (||<1.0, PT>0.5 GeV/c)


PY64 Tune P329

PY64 Tune S320 PY Tune DW

PY Tune DWT

"Toward" Charged Particle Density: dN/dd

0.0

0.4

0.8

1.2

1.6

0 25 50 75 100 125 150

Lepton-Pair PT (GeV/c)

"To

war

d"

Ch

arg

ed D

ensi

tyDrell-Yan

14 TeV

70 < M(pair) < 110 GeV



PY Tune DWT PY Tune DW

PY64 Tune P329 PY64 Tune S320

The amount of activity in “min-bias” collisions.

I believe we are now in a position to make some predictions at the LHC!

PTmax Direction

“Toward”

“Transverse” “Transverse”

“Away”

Z-BosonDirection

“Toward”

“Transverse” “Transverse”

“Away”

The amount of activity in the “underlying event” in hard scattering events.

The amount of activity in the “underlying event” in Drell-Yan events.

If the LHC data are not in the range shown here then

we learn new physics!



SummarySummary We are making good progress in understanding and modeling the

“underlying event”.

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 and Tune DW. At present the new tunes do not fit the data better than Tune A and Tune DW. However, the new tune are theoretically preferred!

Proton AntiProton

PT(hard)

Outgoing Parton

Outgoing Parton




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 the ATLAS tunes!

UE&MB@CMSUE&MB@CMS

Hard-Scattering Cut-Off PT0

1

2

3

4

5

100 1,000 10,000 100,000

CM Energy W (GeV)

PT

0

(Ge

V/c

)

PYTHIA 6.206

= 0.16 (default)

= 0.25 (Set A))

However, I believe that the better fits to the LEP

fragmentation data at high z will lead to small improvements

of Tune A at the Tevatron!

Fermilab Energy Scaling Workshop April 29, 2009 Rick Field – Florida/CDF/CMSPage 1 1 st Workshop...

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Transcript of Fermilab Energy Scaling Workshop April 29, 2009 Rick Field – Florida/CDF/CMSPage 1 1 st Workshop...