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Multi-Particle Azimuthal Correlations at RHIC !!. What do they tell us about Possible Quenching?. Roy A. Lacey USB - Chem (SUNY Stony Brook ). Outline. Motivation General Specific Correlation Technique Assorted-pT method Fixed-pT method Advantages of the Methods - PowerPoint PPT Presentation
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Multi-Particle Azimuthal Multi-Particle Azimuthal Correlations at RHIC !!Correlations at RHIC !!
Roy A. LaceyRoy A. LaceyUSB - ChemUSB - Chem
(SUNY Stony Brook(SUNY Stony Brook))
What do they tell us about Possible Quenching?What do they tell us about Possible Quenching?
Roy A. Lacey HIC03
Outline Outline
Motivation•General• Specific
Correlation Technique • Assorted-pT method• Fixed-pT method• Advantages of the Methods
Correlation Results - Compatible with Jets, Flow, etc. ?- What have we learned ?
See W. Holzman’s Poster
Roy A. Lacey HIC03
The Big Picture
Today’s Cold Universe
Motivation - Motivation - GeneralGeneral
What can we learn from experiments about this past history?What can we learn from experiments about this past history?
Roy A. Lacey HIC03
CGC: Provides
insights on Saturation Physics
Correlation Studies can provide information on the particle Correlation Studies can provide information on the particle production mechanism,the EOS, Initial State effects, production mechanism,the EOS, Initial State effects,
QGPQGP formation formation…. (Very Important Signal)…. (Very Important Signal)
Flow: Primarily from
pressure build-up
Reflect conditions in collision zone (EOS)
Motivation - Why Study CorrelationsMotivation - Why Study Correlations
Jets: Primarily from
gluons at RHIC Sensitive to the
QCD medium (dE/dx)
hadrons
q
q
hadrons leadingparticle
leading particle
schematic view of jet production
Roy A. Lacey HIC03
Striking difference between d+Au and Au+Au results.• Cronin effect dominate in d+Au• High-pT Jet Suppression dominate in Au+Au.
Au + Au Experiment d + Au Control Experiment
Preliminary DataFinal Data
Reminder - Single Particle Distributions Reminder - Single Particle Distributions
Roy A. Lacey HIC03
What Insights do Correlation MeasurementsWhat Insights do Correlation MeasurementsProvide ??Provide ??
y
x
Energy loss can result in an anisotropy which can
serve as a probe of the medium
Roy A. Lacey HIC03
y
xSTAR @ 200 GeV
Extreme Quenching not Sufficient to Account forExtreme Quenching not Sufficient to Account forObserved NObserved Npart part Dependence of VDependence of V22
B. Muller nucl-th/0208038
The Problem The Problem
V2 from calculations which assume quenching
Roy A. Lacey HIC03
Measuring Azimuthal CorrelationsMeasuring Azimuthal Correlations
Study Correlation Study Correlation Functions:Functions:•Uncertainties Uncertainties associated with associated with Acceptance, efficiency, Acceptance, efficiency, etc Reducedetc Reduced
Wang et al., Wang et al., PRC 44, 1091 (1991)PRC 44, 1091 (1991)Lacey et al. Lacey et al. PRL 70, 1224 (1993)PRL 70, 1224 (1993)
Au+Au ???
Measure Distributions
(STAR)
PHENIX uses an Azimuthally Asymmetric Detector
Roy A. Lacey HIC03
First Application of the Azimuthal Correlation Technique at RHICFirst Application of the Azimuthal Correlation Technique at RHIC
Constructing Correlation FunctionsConstructing Correlation Functions
_
( )( )
( )real
mixed events
NC
N
_
( )( )
( )real
mixed events
NC
N
Wang et al., Wang et al., PRC 44, 1091 (1991)PRC 44, 1091 (1991)
Lacey et al. Lacey et al. PRL 70, 1224 (1993)PRL 70, 1224 (1993)
Roy A. Lacey HIC03
Azimuthal Distributions and Correlation FunctionsAzimuthal Distributions and Correlation Functionsare Characterized by an Anisotropy and an Asymmetry.are Characterized by an Anisotropy and an Asymmetry.
deg.)
0 20 40 60 80 100 120 140 160 180
C(
0.8
0.9
1.0
1.1
1.2
Anisotropy ( ) 2v
Approach - 1
2
2
2
11 2 cos(2 ) exp
( ) 2
dNa v
d
Asymmetry ( )
Definition
Roy A. Lacey HIC03
Information in Correlation Functions
Jets lead to strong Jets lead to strong anisotropy and an anisotropy and an asymmetryasymmetry
HIJINGHIJING
Flow leads to strong Flow leads to strong anisotropy – no asymmetryanisotropy – no asymmetry
• The anisotropy of the correlation function can reflectThe anisotropy of the correlation function can reflectboth flow and Jet contribution both flow and Jet contribution
• The Asymmetry provides crucial Jet InformationThe Asymmetry provides crucial Jet Information
deg.)
0 20 40 60 80 100 120 140 160 180
C(
0.8
0.9
1.0
1.1
1.2
Hydro or TransportHydro or TransportWith large OpacityWith large Opacity
Saturation ModelSaturation Model
Mini-Jets, lead to Mini-Jets, lead to strong anisotropy strong anisotropy and an asymmetryand an asymmetry
Roy A. Lacey HIC03
22 2( ) ( ' ( ))tv fix v p
22 2( ) ( ' ( ))tv fix v p
pT
2 ( )v fix2 ( )v fix
'2 ( )tv p
'2 ( )tv p
v2 characterize the Anisotropy
2
2
2
11 2 cos(2 ) exp
( ) 2
dNa v
d
pT_ref 0.4 - 0.8
Cent 6 - 11
0.85 < pT < 1.05
0 50 100 150
Delta Phi
0.95
0.96
0.97
0.98
0.99
1
1.01
1.02
1.03
C
0.95
0.96
0.97
0.98
0.99
1
1.01
1.02
1.03
Extracting v2 via Fixed Correlations
Roy A. Lacey HIC03
Extracting v2 via Assorted Correlations
pT
22 Ref
2
( )pTP
vv
22 Ref
2
( )pTP
vv
Ref2v
Ref2v
2
2
11 2 cos(2 ) exp
( ) 2
dNa P
d
pT_ref 0.4 - 0.8
Cent 6 - 11
0.85 < pT < 1.05
0 50 100 150
Delta Phi
0.95
0.96
0.97
0.98
0.99
1
1.01
1.02
1.03
C
0.95
0.96
0.97
0.98
0.99
1
1.01
1.02
1.03
pT_ref 0.4 - 0.8
Cent 6 - 11
0.85 < pT < 1.05
0 50 100 150
Delta Phi
0.95
0.96
0.97
0.98
0.99
1
1.01
1.02
1.03
C
0.95
0.96
0.97
0.98
0.99
1
1.01
1.02
1.03
2
2Ref2
11 2 cos(2 ) exp
( ) 2
dNa v
d
pT2P2P
Reference
Roy A. Lacey HIC03
200 NNs GeV
PHENIX Preliminary
d+Au Assorted-pT Correlation Functions
Di-jet structure develops with increasing pT
Roy A. Lacey HIC03
`d+Aud+Au
Min BiasMin BiasAu+AuAu+Au60-90%60-90%
Peripheral Au+Au is essentially identical d+Au Peripheral Au+Au is essentially identical d+Au
Comparison of d+Au and Au+Au
200 NNs GeV
Roy A. Lacey HIC03
C(
)
0.9
1.0
1.1
1.2
1.3 0.5 < pT < 1.0 (GeV/c)
C(
)
0.99
1.00
1.01
1.02
1.030.5 < pT < 1.0 (GeV/c)
deg.0 30 60 90 120 150 180
C(
)
0.99
1.00
1.01
1.02
1.032.0 < pT < 3.0 (GeV/c)
deg.0 30 60 90 120 150 180
C(
)
0.9
1.0
1.1
1.2
1.3 2.0 < pT < 3.0 (GeV/c)
d+Au Au+Au (0-5%)
Comparison of d+Au and Au+Au
200 NNs GeV
Escaping Jet“Near Side”
Suppressed Jet
“Away Side”
d+Aud+AuMin BiasMin Bias
Au+AuAu+Au0-5%0-5%
Apparent “away-side suppression
Roy A. Lacey HIC03
C(
)
0.9
1.0
1.1
1.2
1.3 0.5 < pT < 1.0 (GeV/c)
C(
)
0.95
1.00
1.05
1.100.5 < pT < 1.0 (GeV/c)
deg.0 30 60 90 120 150 180
C(
)
0.95
1.00
1.05
1.102.0 < pT < 3.0 (GeV/c)
deg.0 30 60 90 120 150 180
C(
)
0.9
1.0
1.1
1.2
1.3 2.0 < pT < 3.0 (GeV/c)
d+Au Au+Au (20-40%)
d+Aud+AuMin BiasMin Bias
Au+AuAu+Au20- 40%20- 40%
200 NNs GeV
Mid-Central events indicate sizeable harmonic contributionsMid-Central events indicate sizeable harmonic contributions
Comparison of d+Au and Au+Au
Roy A. Lacey HIC03
Comparison of 130 and 200 GeV Results
Anisotropy (v2) essentially identical
PHENIX Preliminary
Roy A. Lacey HIC03
Model performance depend on pT rangeModel performance depend on pT range All models Require Humongous Energy DensitiesAll models Require Humongous Energy Densities
Differential v2 200 NNs GeV
Minimum Bias
2 2 2Rx Tpc Cumv v v
Roy A. Lacey HIC03
It is important to test for these different scaling It is important to test for these different scaling behavior !behavior !
Centrality Dependence of v2
2 2
2 2
<y > - <x >=
<y > + <x >
Different Models predict different scaling Different Models predict different scaling behavior for the centrality dependence of v2behavior for the centrality dependence of v2
•Hydro/Molnar --- eccentricity scalingHydro/Molnar --- eccentricity scaling•Minijet – Overlap Area scalingMinijet – Overlap Area scaling
1~
partN
y
x
eccentricity
Roy A. Lacey HIC03
NPart
0 100 200 300 400
v2
0.0
0.1
0.2
0.3
0.4
2.5 < pT < 4.0 (GeV/c)
PHENIX PRELIMINARY
Cent
0.0 0.1 0.2 0.3 0.4
v2
0.0
0.1
0.2
0.3
0.4
2.5 < pT < 4.0 (GeV/c)
PHENIX PRELIMINARY
Cent
Centrality DependenceCompatible with:
Npart scaling
scaling
1PartN
200 NNs GeV
Scaling compatible with quenching and Flow Scaling compatible with quenching and Flow
Roy A. Lacey HIC03
“v2 pT Scaling”
“High” and “low” pT charged hadrons show similar scaling Common denominator ?
Roy A. Lacey HIC03
V2 Scaling observed in modelsV2 Scaling observed in models
v2 Scaling
pT (GeV/c)
0 1 2 3 4
v 2(p
T,b
)/v2
(b)
0
1
2
3 b ~ 5.3b ~ 6.2b ~ 7.1b ~ 10.9
Molnar et al.
“v2 Centrality Scaling”
Roy A. Lacey HIC03
pT (GeV/c)
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
v 2(p
T,C
entr
alit
y)/v
2(C
entr
alit
y)
0
1
2
3
4
5
6
05-10 10 -20 20 - 40 40 - 60 60 - 90
Centrality (%)
Two Different scaling patterns are obtained --- Respective dominance of Jets and flow-like contributions
Preliminary00-05
“v2 centrality Scaling”
Roy A. Lacey HIC03
vv22 does not show significant dependence on pT does not show significant dependence on pTRefRef
Very Important --- vVery Important --- v22(rxpln) ~ v(rxpln) ~ v22(corr)(corr)
Reference Range Dependence
pT
2 ( )P assor
R2
pT (GeV/c)
1 2 3 4 5
v2
0.0
0.1
0.2
0.31.0 < pTRef < 2.
0.5 < pTRef < 1.0
20 < Cent < 40
PHENIX PRELIMINARY
200 NNs GeV
Roy A. Lacey HIC03
Assorted Correlation Functions for p+p & Au+Au
• Asymmetry of Correlation
function sensitive to:• pTRef
• Charge Selection
Consistent with presence of
Jets
C
0.96
0.98
1.00
1.02
1.04
C
0.96
0.98
1.00
1.02
1.04
0 40 80 120 160
C
0.5
1.0
1.5
2.0
2.5
0 40 80 120 160
C
0.5
1.0
1.5
2.0
2.5
PP
Au-Au
Re1.0 3.0
fTp Re
0.3 1.0fTp
pT
2( )P assor
R2
Jets correlated with Reaction planeJets correlated with Reaction plane
Roy A. Lacey HIC03
Jet-quenching earlyJets “remember” geometry (-> v2)
… then thermalized matter expands From pressure build up -> elliptic flow-> v2
Summary/PictureSummary/Picture
Consistent picture for quenching, v2, jets
Observables:
high & low pT particles are correlated v2 independent of pT reference range scaling of v2 away-side jet suppressed in central collisions
proven
provenprovenproven
Jets are correlated with the Reaction Plane due to Quenching
