levan babukhadia

TeV81at CollisionsinSection CrossJet Inclusive Single

the of Dependence Rapidity

.spp TeV81at CollisionsinSection CrossJet Inclusive Single

the of Dependence Rapidity

.spp

Levan BabukhadiaLevan Babukhadia

University of ArizonaTucson, AZ

University of ArizonaTucson, AZ

DØ CollaborationBatavia, IL

DØ CollaborationBatavia, IL

1999 D WorkshopJune 27 - July 2, 19991999 D WorkshopJune 27 - July 2, 1999

University of WashingtonSeattle Washington USA

University of WashingtonSeattle Washington USA

http://www-d0.fnal.gov/~blevan/stl99/index.htm

1999 D Workshop Seattle, Washington 29 June 1999

To be published in Phys. Rev. Lett. 82, 2451 (1999)Also see hep-ex/9807018

To be published in Phys. Rev. Lett. 82, 2451 (1999)Also see hep-ex/9807018

The DØ Central Inclusive Jet Cross SectionThe DØ Central Inclusive Jet Cross Section

1

pb 92 Ldt

1

pb 92 LdtDØ Run 1BDØ Run 1B

0.0 0.5 JETRAD

statistical errors only

PDF, substructure, … ?

d2 /d

ET

d

ET

How well do we know proton structure (PDF)?

Is NLO ( ) QCD “sufficient”?

Are quarks composite?

3sα


Inclusive Jet Cross Section as aTest of the Standard Model (pQCD)

Inclusive Jet Cross Section as aTest of the Standard Model (pQCD)

1P1P

2P2P

11Px 11Px

22Px 22Px

1jet1jet

2jet2jet

s s

1/ xf Aa 1/ xf Aa

2/ xf Bb 2/ xf Bb )(ˆ

)2(

2/1/21

21

cdabxfxfdxdx

jetspp

abcdBbAa

)(ˆ

)2(

2/1/21

21

cdabxfxfdxdx

jetspp

abcdBbAa

T

T

jet

TT

T

ELdtE

N

ddE

dEdd

E vs.

1 2

T

T

jet

TT

T

ELdtE

N

ddE

dEdd

E vs.

1 2

binthe in jets of N

Luminosity inst.Lsize bin

efficiency selectionsize binEE

jet

TT

#

binthe in jets of N

Luminosity inst.Lsize bin

efficiency selectionsize binEE

jet

TT

#

Single Inclusive Jets:Single Inclusive Jets: X jetpp X jetpp


Data SampleData Sample

Run # 72250 93115December 1993 July 1995

Run # 72250 93115December 1993 July 1995

1

pb 92 Ldt

1

pb 92 LdtRun 1BRun 1B

The four single jet triggers areused for different jet ET ranges

where at least 99% efficient:

The four single jet triggers areused for different jet ET ranges

where at least 99% efficient:

Jet_30:Jet_50:Jet_85:

Jet_Max:

Jet_30:Jet_50:Jet_85:

Jet_Max:

ET ~ 60 90 GeVET ~ 90 130 GeVET ~ 130 170 GeVET ~ 170 Max GeV

ET ~ 60 90 GeVET ~ 90 130 GeVET ~ 130 170 GeVET ~ 170 Max GeV

1pb 92

~ dtL1

pb 55

~ dtL

Jet_30 Jet_50

Jet_85 Jet_Max

1pb 4.6

~ dtL1

pb 0.34

~ dtL

scm10L 30 2

Luminosity profiles ofRun 1B single jet filters:Luminosity profiles of

Run 1B single jet filters:


Jet Production and ReconstructionJet Production and Reconstruction

Tim

ep p

q

q g

K

part

on je

tpa

rtic

le je

tca

lori

met

er je

t

hadrons

CH

FH

EM

RECO v.12Fixed-cone jetsAdd up towers

Iterative processJet quantities

RECO v.12Fixed-cone jetsAdd up towers

Iterative processJet quantities

7.0iR

towerT

jetT EE

7.0iR

towerT

jetT EE

mET ,,, mET ,,,

70.R

),( 00 ),(

Corrections to RECO:Corrections to RECO:AIDA Cell Restoration

HT Re-vertexingTotal -Bias Correction (TEB)

AIDA Cell RestorationHT Re-vertexing

Total -Bias Correction (TEB)


Effects of RECOE

ffec

ts o

f D

vs.

Sn

owm

ass

defi

ni ti

ons

SNPJ SNCJ

DCJDPJ

D0recδ

totδCJalgδ

PJalgδ

SNrecδ

SNPJ - Particle Jets Reconstructed with Snowmass AccordSNCJ - Calorimeter Jets Reconstructed with Snowmass AccordDPJ - Particle Jets Reconstructed with D AlgorithmDCJ - Calorimeter Jets Reconstructed with D Algorithm

For any jet quantity (, , ET , ... ), one of the five biases from the cartoon on the left (i.e. with corresponding super- and subscripts, also represented by a vector) is defined as:

= 1 - 2 ,

where 1 is the jet quantity at the endpoint of the corresponding vector and 2 is the quantity at the origin of the vector. It is also obvious that following hold:

SNrec

CJalgtot

D0rec

PJalgtot

δ δ ~δ,δ δ ~δ

Origin of -BiasOrigin of -Bias


<

>

Herwig-Showerlib MC.

Biases due to algorithmsand reconstruction goin opposite directions,nearly canceling each

other out.

The residual or the Totalof these two is what we

measure and correct for.

Closer Look at -BiasCloser Look at -Bias


Total -Bias Correction Closure

R < 0.7 ET > 10 GeVAll energies

before the correction after the correction

TEB parameterized as afunction of in various

bins of jet energy.

(1) Snow/D -- same ET.(2) RECO bias does notcause different towers to be assigned to the jet -- no ET bias.

Jet only is corrected for TEB because:

TEB parameterization closure is excellent!

Total -Bias CorrectionTotal -Bias Correction


Highest ET dijet event at DØHighest ET dijet event at DØ

69.0GeV, 472

69.0GeV, 47522

11

T

T

E

E

Data SelectionData Selection

• EMF < 0.95 in the ICR, 0.05 < EMF < 0.95 everywhere else. • CHF < 0.60 in the ICR, CHF < 0.40 everywhere else.• HCF > 0.05 everywhere (applied on non-restored jets only).

• EMF < 0.95 in the ICR, 0.05 < EMF < 0.95 everywhere else. • CHF < 0.60 in the ICR, CHF < 0.40 everywhere else.• HCF > 0.05 everywhere (applied on non-restored jets only).

Acceptance:|Zvrt| < 50 cm ~ 90%

Acceptance:|Zvrt| < 50 cm ~ 90%

Event Quality:Event Quality:

7.0leadT

missT

E

E7.0

leadT

missT

E

E

~ 98 - 99% ~ 98 - 99%

Jet Quality Cuts (comb = EMF CHF HCF ~ 98 - 99%):Jet Quality Cuts (comb = EMF CHF HCF ~ 98 - 99%):


Luminosity Dependence Ruled OutLuminosity Dependence Ruled Out

No significant Lum. dep.of the “shape” established

For the “shape” dependence, studied ratios of ET spectra from low, high, medium, and total inst. Lum. sub-samples:

For the “normalization” dep., studied ratios from various Lum. sub-samples by Runs, recalculating integrated Lum.:


The Jet Energy Scale Correction (JES)The Jet Energy Scale Correction (JES)

Goal: Calorimeter jet Particle jet (Energy correction)

No central tracking B field at DØ Jet calibration real challenge

conejet

measjetptcl

jet S R

OEE

conejet

measjetptcl

jet S R

OEE

JES has been verified by an independent test

based on ET balance in the -jet and jet-jet sub-samples

JES has been verified by an independent test

based on ET balance in the -jet and jet-jet sub-samples

To be published in Nucl. Instr. Meth. A424, 352 (1999)To be published in Nucl. Instr. Meth. A424, 352 (1999)

ppq

q

• Offset (O): Ur noise, pileup, &

underlying event

• Showering (1/Scone): out-of-cone

shower losses

• Response (Rjet): Emeas / Etrue (from ET balance in -jet data)

CH

FH

EM

hadrons

Cafix 5.2


Jet Energy Scale Closure TestJet Energy Scale Closure Test

)ˆ(

)ˆ(

0)ˆ(

0)ˆ(

nE

nER

iT

nE

nE

iT

iT

iT

x

y

or Jet 1

Jet 2

Jet 3

n

Based on PT balance in -jet and jet-jet data.

-jet and jet-jet data in excellent agreement in the region of overlap.

Major systematics of the jet-jet method:

(a) Resolution Bias.

(b) UnClustered Energy(UCE) Correction.

R is to be studied as a function of forward jet energy in various jet regions.


Resolution Bias and UCE CorrectionResolution Bias and UCE Correction

FORjet

FORT

CENT CoshEEE )(

21

The new variable:

removes bias to within 0.5 1%.

The UCE correction (~0.5 1.5%)

derived entirely from the data and

confirmed in the MC study.


Results of the JES Closure TestResults of the JES Closure Test

Cafix 5.2 Closure good within the uncertainties of JES (2 5%) and the test itself (1 1.5%), and Cafix 5.2 does better at highest than Cafix 5.1.

We recommend this Closure test as a standard for verifying any future D JES.

Cafix 5.2

Cafix 5.2 Cafix 5.2

Cafix 5.2

Cafix 5.2 Cafix 5.2


ET: 210 240 GeV0.0 0.5

Cafix 5.2

Asymmetry

En

trie

s

“observed”“true”“smearing”

“unsmearing” or “unfolding”

E0

21

21

TT

TT

EEEE

A

Dijet Asymmetry:

AT

EE

EET

2~

In case of small Z

When Z 0 consider Same Side (SS) and Opposite Side (OS) dijet events separately!

2

2

21

EESS

A

222

OSA

SSA

T

E σσE

σT

EC in,21

CC in,241

21

422

2

222

2

CosZE

SinRE

cal

ZEOSA

cal

ZEOSA

... but need to consider effects of E & Z

separately!

... but need to consider effects of E & Z

separately!

Resolutions and SmearingResolutions and Smearing


Measuring Jet Energy ResolutionsMeasuring Jet Energy Resolutions

Select good dijet events:(1) “back-to-back” cut.(2) ET

3 cut.

Fit Asymmetry to Gaussian.

Apply Soft Radiation Correctionby extrapolating resolutions

obtained with various ET3 cuts

down to “ideal” dijet with ET3 = 0.

Subtract Particle Level Imbalance (PLI) measured from Herwig MC:even in the particle level, dijets do

not perfectly balance due tothe finite cone-size and particles

fluctuating outside algorithm cone.

1.5 2.0, Cafix 5.2, ET: 95 150 GeVDerivation of Soft Radiation Correction

ET3 < 8 GeV

ET3 < 12 GeV

ET3 < 10 GeV

ET3 < 15 GeV

ET3 < 20 GeV Extrapolation to ET

3 = 0 GeV

Asymmetry

Asymmetry Asymmetry

Asymmetry Asymmetry

ET (GeV)


Jet Energy ResolutionsJet Energy Resolutions2

2

2

2

036.0685.0652.2

TT

E

EEE

0.0 0.5 1.0 1.50.5 1.0

1.5 2.0 2.0 3.0

22

2

2

051.0726.0934.0

TT

E

EEE

22

2

2

054.0433.0515.0

TT

E

EEE2

2

2

2

001.0502.0546.1

TT

E

EEE

22

2

2

071.0197.0161.5

TT

E

EEE

Jet energy resolutionsare measured from SSdijet Asymmetry andare parameterized as a function of jet ET in

various regions.


Effects of Vertex ResolutionEffects of Vertex Resolution

0.5 1.0

0.0 0.5

1.0 1.5

1.5 2.0

2.0 3.0

Effects of non-zero Z studied in JETRAD.

Conservative estimate of Z measured from the differences in SS/OS

asymmetry resolutions is 7.5 cm.Study ratios of raw cross sectionsfrom Jetrad with and without

vertex smearing of Z = 7.5 cm.Effect on the cross section

is ~ 1 - 2% in ALL regions negligible!

Effect on the cross section is ~ 1 - 2% in

ALL regions negligible!


Unfolding of Jet Energy ResolutionsUnfolding of Jet Energy Resolutions

The Ansatz function

sE

EeEF TTT

21)(

smeared by energyresolutions is fittedto data fixing thefour free parameters.


Unfolding correctionis given by bin-by-binratio of the ”true” to smeared ansatz functions. Data isre-scaled by thesefactors in every ET

bin and region.

Unfolding Correction for all RegionsUnfolding Correction for all Regions


ET (GeV)

d2 d

ET

d

(fb

/GeV

) 0.0 0.5 0.5 1.0 1.0 1.5 1.5 2.0 2.0 3.0

DØ PreliminaryDØ Preliminary

1

pb 92 Ldt

1


Nominal cross sections & statistical errors only

Rapidity Dependence of the Inclusive Jet Cross Section

Rapidity Dependence of the Inclusive Jet Cross Section


ET (GeV)

Fra

ctio

nal E

rror

s (%

)

0.0 0.5

0.5 1.0

1.0 1.5

Sources of Systematic UncertaintiesSources of Systematic Uncertainties


1

pb 92 Ldt

1


ET (GeV)

1.5 2.0

2.0 3.0

Total Jet Energy Scale Resolutions & Unfolding Luminosity Selection efficiency

1999 D Workshop Seattle, Washington 29 June 1999ET (GeV)

Fra

ctio

nal

Err

ors

(%)

0.0 0.5

0.5 1.0

1.0 1.5



ET (GeV)

Fra

ctio

nal E

rror

s (%

)


1.5 2.0

2.0 3.0

Total Jet Energy Scale Resolutions & Unfolding Luminosity Selection efficiency


0.5 1.0

0.0 0.5

1.0 1.5

ET (GeV)



Comparisons to Theoretical (JETRAD) PredictionsComparisons to Theoretical (JETRAD) Predictions


( D

a ta

- T

he o

r y )

/ T

he o

r y

1.5 2.0

2.0 3.0



ET (GeV)

Comparisons to JETRAD with:

PDF: CTEQ3M

Rsep= 1.3

2ETmax Good agreement with theory

over seven orders.

Deviations from QCD at highest ET not significant within errors.

Good agreement with theory over seven orders.

Deviations from QCD at highest ET not significant within errors.


0.5 1.0

0.0 0.5

1.0 1.5

ET (GeV)





( D

a ta

- T

he o

r y )

/ T

he o

r y

PDF: CTEQ3M

Rsep= 1.3

2ETmax




( D

a ta

- T

he o

r y )

/ T

he o

r y

1.5 2.0

2.0 3.0



ET (GeV)

Comparisons to JETRAD with:

PDF: CTEQ3M

Rsep= 1.3

2ETmax


Summary

Reported on Rapidity Dependence of the Inclusive Jet Production Cross

Section (up to | | of 3.0).

Good agreement with NLO pQCD is observed with no statistically

significant discrepancy.

Summary

Reported on Rapidity Dependence of the Inclusive Jet Production Cross

Section (up to | | of 3.0).

Good agreement with NLO pQCD is observed with no statistically

significant discrepancy.

Outlook

Error correlation MC study underwayto facilitate quantitative Data to Theory comparisons (such as the 2 tests).

First draft of the paper ready by the end of summer.

Outlook

Error correlation MC study underwayto facilitate quantitative Data to Theory comparisons (such as the 2 tests).

First draft of the paper ready by the end of summer.

levan babukhadia

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