What do we learn from

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What do we learn from Correlation measurements at
RHIC
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Motivation
Which observables phenomena connect to the
de-confined stage?
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Flow correlations provide an important probe
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Prologue
Low Energy Squeeze-out
High Energy In-plane
Do we understand Flow correlations ?
Pressure Gradients Drive Transverse and Elliptic
flow
The expected transition Is observed
Phys.Rev.Lett.831295,1999
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What information do Flow correlations provide?

• Provides reliable estimates of pressure
  pressure gradients
• Can address questions related to thermalization
• Gives insights on the transverse dynamics of the
• medium
• Provides access to the properties of the medium
• - EOS, sound speed (cs ), viscosity, etc

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There are two sources of azimuthal correlations
at RHIC !
Azimuthal Correlations Provide Two Direct routes
to the Properties of the High Energy Density
Matter Created at RHIC
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Reminder High Energy density matter is created at
RHIC!
The Energy Density is Well Above the Predicted
Value for the Phase Transition /crossover !
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Reminder Particle production system size
Un-scaled dN/d?
PHOBOS Data
Particle production is essentially geometry
dominated
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Reminder Statistical Model Comparisons of
Particle Ratios
Hadro-chemistry indicates a single Hadronization
Temperature 175 MeV
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Is Thermalization Rapid ?
Self quenching
Substantial elliptic flow signals should be
present for a variety of particle species
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Is Thermalization Rapid ?
Large Pressure Gradients are Generated Very Early
!
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v2 sheet for mesons Baryons
Exquisite Features Due to Radial flow ?
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Is Thermalization Rapid ?
Heavy quark Thermalization ?
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Is the matter unique ?
CERES
Results are strikingly similar for
V2 decreases by 50 from RHIC to SPS
Significantly larger pressure (gradients) at RHIC
than at SPS
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Excitation function for differential v2
Apparent saturation of v2 for
Possible indication for a soft EOS !
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Does the Flow follow ideal hydrodynamics ?
Non-trivial issue for EOS, viscosity, etc
Investigate Hydrodynamic Scaling Relations for
the fine structure of v2
Fit Data
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Fine Structure Scaling
Note Universal Scaling prediction
M. Csanad C. Csörgo et al.
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Scaling Tests
Eccentricity scaling
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Scaling of azimuthal anisotropy - Mesons
PHENIX Preliminary
PHENIX Preliminary

• Scaling works over a broad range for charged
  hadrons
• and identified particles

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Scaling of azimuthal anisotropy - Hydro
Hydro eccentricity scaling
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Scaling of azimuthal anisotropy - system size
PHENIX Preliminary
Scaling of CuCu and AuAu collisions indicate
system size indipendece
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Scaling PHENIX Data
PHENIX Preliminary
5ltCentralitylt30

• Unequivocal scaling at low values
• scaling breaks 1.8

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Scaling of azimuthal anisotropy - hadrons
Integral flow scaling observed across
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Scaling of RHIC data

• Demonstration of higher harmonic scaling

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Scaling of RHIC data

• Demonstration of Comprehensive scaling at RHIC

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Quark number scaling -- Partonic Flow ?
baryons
?? OO ?
mesons
200 GeV AuAu
Hadronic re-scattering does not support observed
Phi flow !
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Extended Fine Structure scaling
PHENIX Preliminary
5ltCentralitylt30
All Flow Data Now Understood
Universal scaling prediction!
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Scaling of azimuthal anisotropy - Hydro
Estimate cs !
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Initial Foray

• Fits to the data can provide estimates of the
  properties of the produced matter

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Epilogue
Correlation measurements give compelling
evidence for the production of strongly
interacting high energy density partonic matter
in RHIC collisions.
sQGP