What do we Learn From Azimuthal Correlation Measurements in PHENIX Roy. A. Lacey Nuclear Chemistry,...

What do we Learn From Azimuthal Correlation Measurements in PHENIX

Roy. A. LaceyNuclear Chemistry, SUNY, Stony Brook

R. Lacey, SUNY Stony Brook

A Cue from Lattice QCD:A Cue from Lattice QCD:

A Cue from Lattice QCD:A Cue from Lattice QCD:

Phase Transition

12 °

3

170 MeV 10 K

1 GeV/fm

T

Probes that indicate equilibrated nuclear matter Probes that indicate equilibrated nuclear matter with with εε > 1 GeV/fm > 1 GeV/fm3 3 are of particular Interestare of particular Interest

Motivation Motivation Motivation Motivation


In-plane Out-of-plane

Correlation Function

HarmonicHarmonic

Jet Function

Azimuthal Correlations Provide Direct Access to the Azimuthal Correlations Provide Direct Access to the Properties of the High Energy Density Matter Created at Properties of the High Energy Density Matter Created at

RHICRHIC

Why is the Correlation Probe Why is the Correlation Probe Compelling ? Compelling ?

Why is the Correlation Probe Why is the Correlation Probe Compelling ? Compelling ?

0

HarmoC Jet Functiorrelation Function onic n

C a H J

Azimuthal Correlationsare derived from Harmonic and di-jet contributions


What Information do Correlation MeasurementsProvide ?

A Direct Route for the Study of Jets• Characterization of Jet Topologies in pp, dA & AA• Quantification of Medium Induced Modifications to Topologies

Crucial for study of the properties of the medium

• Tomographic Imaging of Hot and Dense Partonic Matter

Reliable Pressure Estimates: • Thermalization • Opacity of the Medium

EOSEOS

Simultaneous Study of Harmonic and Jet Correlations is CrucialSimultaneous Study of Harmonic and Jet Correlations is Crucial


The Energy Density is Well Above the Predicted Value for The Energy Density is Well Above the Predicted Value for the Phase Transition !the Phase Transition !

Substantial EnergySubstantial EnergyEnergy Density Created Energy Density Created

at RHIC !at RHIC !

Substantial EnergySubstantial EnergyEnergy Density Created Energy Density Created

at RHIC !at RHIC ! PRL87, 052301 (2001)

Central collisionsperipheral collisions

time to thermalize the system (0 ~ 0.2 - 1 fm/c)Bjorken~ 5 - 15

GeV/fm3

~ 35 – 100 ε0

dy

dE

RT

Bj0

2

11

Extrapolation From EExtrapolation From ETT

DistributionsDistributions


time to thermalize the system (0 ~ 0.2 - 1 fm/c)

Bjorken~ 5 - 15 GeV/fm3

dy

dE

RT

Bj0

2

11

Extrapolation From EExtrapolation From ETT

DistributionsDistributionsIs the Energy Is the Energy Thermalized ?Thermalized ?

Is the Energy Is the Energy Thermalized ?Thermalized ?

s/

P ²

A Reliable Pressure Measurement gives Insight: Elliptic Flow


Correlation FunctionsCorrelation Functions

Substantial Signals Attributable to Flow and Jets are observed ?Substantial Signals Attributable to Flow and Jets are observed ?

PHENIX P

RELIMIN

ARY

PHENIX P

RELIMIN

ARY


VV22 data data

Substantial Signals Atributable to Flow are Substantial Signals Atributable to Flow are observed ?observed ?

Indicative of Early ThemalizationIndicative of Early Themalization

-- Large Pressures, Jets correlate with RP Large Pressures, Jets correlate with RP

phenix preliminarynucl-ex/0305013


v2 apparently Saturatesv2 apparently Saturates Are we in the v2 plateau ?

Energy DependenceEnergy Dependence


Comparison with results from SPSComparison with results from SPS


Very Large Pressure Gradients Non Trivial !!

Scaling not Incompatible with Recombination

Scaling TestsScaling TestsHow Large is the How Large is the

Pressure ?Pressure ?

How Large is the How Large is the Pressure ?Pressure ?

2

2 22

2

1

T TT T

T TT T

v p up u T

T

v p up u T

T

Hydro Limit


Scaled v2 should give similar values !!

Is the Opacity Is the Opacity Large ?Large ?


2

22

2 2

1

TT T

T

TT T

T

v up u T

p T

v up u T

p T

Hydro Limit

pT (GeV/c)

0 1 2 3 4

v 2(p

T,b

)/v

2(b

)

0

1

2

3 b ~ 5.3b ~ 6.2b ~ 7.1b ~ 10.9

Molnar et al.


Scaled v2 compatible with large Opacities



PHENIX Preliminary


Jet CorrelationsJet Correlations

p+p d+A

A+A

Remarkable Probes for High-density Matter Auto-Generated on the right time-scale

Operational Strategy

2 2vac IS nucl

2AA

2FS nuclk kk k

2 2vac IS nucl

2AA

2FS nuclk kk k Observable


nearfar

near-side away-side

c

chbbaa

abcdba

T

hpp

z

Dcdab

td

dQxfQxfdxdxK

pdyd

d

0

/222

)(ˆ

),(),(

hadron

hadron

ΔφTk

Tj

parton

parton

2 2Fa

TTy Near r

pk

z 2 2

FaT

Ty Near r

pk

z

sin Nearyj p

JetJet Correlations Correlations JetJet Correlations Correlations

coneRFragmentation:

hadron

parton

pz

p

Azimuthal Correlations Carry Invaluable Information Azimuthal Correlations Carry Invaluable Information about the di-jetabout the di-jet.


coneRFragmentation:

hadron

parton

pz

p

The Predicted Influence of the The Predicted Influence of the Medium is SpecificMedium is Specific.

far

Jets in Au+Au CollisionsJets in Au+Au Collisions Jets in Au+Au CollisionsJets in Au+Au Collisions

Induced Gluon Radiation

~ collinear gluons in cone

““Softened” fragmentationSoftened” fragmentation I. Vitev, nucl-th/0308028I. Vitev, nucl-th/0308028

2 ( )

( )

T g

g

k x dx

E x x dx

far

in je

i j t

t

n e

: increases

z : decreases

chn

Gyulassy et al., nucl-th/0302077


Jet CorrelationsJet Correlations

p+p d+A

A+A

Operational Strategy

2 2vac IS nucl

2AA

2FS nuclk kk k

2 2vac IS nucl

2AA

2FS nuclk kk k Observable


pp and dAu correlation functions 3.0<pT<6.0

p+p h+-

d+Au

Away side peak

d+Au h

1.0<pT<1.5

1.5<pT<2.0

Fit = const + Gauss(0)+Gauss()

Jet function assumed to be Gaussian

Fixed correlationsFixed correlations:

5.0<pTtrigg <16.0 GeV/c

Assorted correlationsAssorted correlations:

Distinct Di-jet peaksDistinct Di-jet peaks


N ,A |jTy|, |kTy| in p+p

2pp

2vack k

2pp

2vack k

PHENIX preliminary

|jTy| = 35911 MeV/c

|kTy| = 96449 MeV/c

PHENIX preliminary

|jTy| = 35911 MeV/c

|kTy| = 96449 MeV/c

|jTy| and |kTy| ingood agreement with prior measurements: PLB97 (1980)163 PRD 59 (1999) 074007

A

PHENIX preliminary


d+Au

|jTy| similar to that for pp – No Surprise !!

pp


d+Au

No significant kT-broadening seen in dAu data

I.Vitev

I.Vitev nucl-th/0306039

vac IS nucdAu l22 2k k k vac IS nucdAu l

22 2k k k


Area under curve

Total Area

fraction of pairsthat are correl. jet pairs

pairstotal

pairsjet

n

n

dassocdtrig

dpairstotal

nn

n

dassocdtrig

pairscorrel

nn

n

dassocdtrig

pairscorrel

nn

n

correffassocn trig

pairscorrel

n

n

correlated jet-pairs over combinatoric background

conditional yields are corrected for -acceptance & efficiency, and are reported in the PHENIX -acceptance ( | | < 0.35 ).

Conditional-YieldsConditional-Yields Conditional-YieldsConditional-Yields


Calibrated SignalCalibrated Signal Calibrated SignalCalibrated Signal

trig

pairscorrel

n

n

pairstotal

pairsjet

n

n

Expected Yield Dependence


coneRFragmentation:

hadron

parton

pz

p

Is the Away-side Jet Broadened in Is the Away-side Jet Broadened in Au+ Au Collisions ?Au+ Au Collisions ?

Is the Away-side Jet Broadened in Is the Away-side Jet Broadened in Au+ Au Collisions ?Au+ Au Collisions ?

2 ( )

( )

T g

g

k x dx

E x x dx

Associated charged hadrons Associated charged hadrons and mesons show centrality and mesons show centrality

dependent broadening of dependent broadening of away-side jet away-side jet Modification Modification

d+Au


Centrality Dependence of conditional Jet yieldsCentrality Dependence of conditional Jet yields

• Charged hadron yields Charged hadron yields show apparent away-side show apparent away-side suppression ?suppression ?

Escaping Jet“Near Side”

Suppressed Jet

“Away Side”

q

q


Several Trigger Requirements have been exploitedSeveral Trigger Requirements have been exploited

Flavor Composition of Jets in Flavor Composition of Jets in Au + AuAu + Au


AssociatedAssociatedMesonsMesons

2.5 4.0 GeV/c

1.0 2.5 GeV/c

Trigg

Assoc

pT

pT

AssociatedAssociatedBaryonsBaryons

Trigger HadronTrigger HadronTrigger BaryonTrigger Baryon Trigger MesonTrigger Meson

AssociatedAssociatedHadronsHadrons


0.8

0.9

1.0

1.1

0 40 80 120 160

C

0.8

0.9

1.0

1.1

0 40 80 120 160 0 40 80 120 160 0 40 80 120 160 0 40 80 120 160

Cent: 0-5% 05-10% 10-20% 20-40% 40-60%

deg.)

AssociatedAssociatedMesonsMesons

/

2.5 4.0 GeV/c

1.0 2.5 GeV/cM B

LH

A

pT

pT

PHENIX Preliminary

AssociatedAssociatedBaryonsBaryons

Correlation Functions for associated Baryons are Dominated by Correlation Functions for associated Baryons are Dominated by Harmonic ContributionsHarmonic Contributions




Centrality Dependence of conditional Jet yieldsCentrality Dependence of conditional Jet yields

• Charged hadron yields Charged hadron yields show apparent away-side show apparent away-side suppressionsuppression

• Hadron yields dominated Hadron yields dominated by Mesonsby Mesons

• Similar near- and away-Similar near- and away-side for associated baryons.side for associated baryons.

Escaping Jet“Near Side”

Suppressed Jet

“Away Side”

q

q


The Observed baryon to meson ratio is The Observed baryon to meson ratio is higher for away-side jetshigher for away-side jets

Baryon to Meson Ratio for Away-side JetBaryon to Meson Ratio for Away-side Jet


Story is different !!Story is different !!


High energy-density matter is created at RHIC.High energy-density matter is created at RHIC. Correlation measurements Suggests a State of Matter Correlation measurements Suggests a State of Matter

not heretofore seennot heretofore seen

Pressure Gradients Pressure Gradients Develop in Partonic Develop in Partonic matter -> elliptic flow -matter -> elliptic flow -> v2> v2

Au+Au Collisions at RHICAu+Au Collisions at RHIC

High Density High Density Thermalized Thermalized partonic material partonic material formed Earlyformed Early

Hard Scattered PartonsHard Scattered PartonsTraverse partonic materialTraverse partonic material Jet-quenching (early) & Jet-quenching (early) & v2v2

q

q

leadingleadingparticleparticle

d + Au leadingleadingparticleparticle

Expansion followedby

Hadronization


In-plane

Out-planeX.N. Wang

Angular Dependent Angular Dependent Jet Modification Jet Modification

should be an should be an Important Important

ObservableObservable

Di-Jet Tomography: The Next FrontierDi-Jet Tomography: The Next Frontier

2dEl

dx


High Density High Density partonic material partonic material formed formed

q

q

leadingleadingparticleparticle

d + Au leadingleadingparticleparticle

Jet Quenching and Flow have a common denominatorJet Quenching and Flow have a common denominator(eccentricity)

Expectations:

Evidence for High Energy-Density Evidence for Quenching High & low pT particles correlated v2 essentially independent of pTRef

v2 Factorization ~ Eccentricity Scaling of v2 for high pT Away-side Jet suppression in central collisions Suppression Dependence on Orientation Modification of Jet Properties

What do we Learn From Azimuthal Correlation Measurements in PHENIX Roy. A. Lacey Nuclear Chemistry,...

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