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
1999 D Workshop Seattle, Washington 29 June 1999
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
1999 D Workshop Seattle, Washington 29 June 1999
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:
1999 D Workshop Seattle, Washington 29 June 1999
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)
1999 D Workshop Seattle, Washington 29 June 1999
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
1999 D Workshop Seattle, Washington 29 June 1999
<
>
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
1999 D Workshop Seattle, Washington 29 June 1999
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
1999 D Workshop Seattle, Washington 29 June 1999
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%):
1999 D Workshop Seattle, Washington 29 June 1999
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.:
1999 D Workshop Seattle, Washington 29 June 1999
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
1999 D Workshop Seattle, Washington 29 June 1999
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.
1999 D Workshop Seattle, Washington 29 June 1999
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.
1999 D Workshop Seattle, Washington 29 June 1999
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
1999 D Workshop Seattle, Washington 29 June 1999
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
1999 D Workshop Seattle, Washington 29 June 1999
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)
1999 D Workshop Seattle, Washington 29 June 1999
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.
1999 D Workshop Seattle, Washington 29 June 1999
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!
1999 D Workshop Seattle, Washington 29 June 1999
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.
1999 D Workshop Seattle, Washington 29 June 1999
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
1999 D Workshop Seattle, Washington 29 June 1999
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
pb 92 LdtRun 1BRun 1B
Nominal cross sections & statistical errors only
Rapidity Dependence of the Inclusive Jet Cross Section
Rapidity Dependence of the Inclusive Jet Cross Section
1999 D Workshop Seattle, Washington 29 June 1999
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
DØ PreliminaryDØ Preliminary
1
pb 92 Ldt
1
pb 92 LdtRun 1BRun 1B
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
Sources of Systematic UncertaintiesSources of Systematic Uncertainties
1999 D Workshop Seattle, Washington 29 June 1999
ET (GeV)
Fra
ctio
nal E
rror
s (%
)
Sources of Systematic UncertaintiesSources of Systematic Uncertainties
1.5 2.0
2.0 3.0
Total Jet Energy Scale Resolutions & Unfolding Luminosity Selection efficiency
1999 D Workshop Seattle, Washington 29 June 1999
0.5 1.0
0.0 0.5
1.0 1.5
ET (GeV)
DØ PreliminaryDØ Preliminary
DØ PreliminaryDØ Preliminary
Comparisons to Theoretical (JETRAD) PredictionsComparisons to Theoretical (JETRAD) Predictions
DØ PreliminaryDØ Preliminary
( D
a ta
- T
he o
r y )
/ T
he o
r y
1.5 2.0
2.0 3.0
DØ PreliminaryDØ Preliminary
DØ PreliminaryDØ Preliminary
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.
1999 D Workshop Seattle, Washington 29 June 1999
0.5 1.0
0.0 0.5
1.0 1.5
ET (GeV)
DØ PreliminaryDØ Preliminary
DØ PreliminaryDØ Preliminary
Comparisons to Theoretical (JETRAD) PredictionsComparisons to Theoretical (JETRAD) Predictions
DØ PreliminaryDØ Preliminary
( D
a ta
- T
he o
r y )
/ T
he o
r y
PDF: CTEQ3M
Rsep= 1.3
2ETmax
DØ PreliminaryDØ Preliminary
1999 D Workshop Seattle, Washington 29 June 1999
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
DØ PreliminaryDØ Preliminary
DØ PreliminaryDØ Preliminary
ET (GeV)
Comparisons to JETRAD with:
PDF: CTEQ3M
Rsep= 1.3
2ETmax
1999 D Workshop Seattle, Washington 29 June 1999
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.
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