phenix studies of the scaling properties of elliptic flow at rhic energies
DESCRIPTION
PHENIX Studies of the Scaling Properties of Elliptic Flow at RHIC energies. Arkadij Taranenko. Nuclear Chemistry Group SUNY Stony Brook, USA. for the PHENIX Collaboration. Winter Workshop on Nuclear Dynamics Big Sky , MT February 12-17,2007. Why Elliptic Flow ?. Z. - PowerPoint PPT PresentationTRANSCRIPT
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R. Lacey, SUNY Stony Brook
Arkadij Taranenko
Winter Workshop on Nuclear Dynamics Big Sky , MT February 12-17,2007
Nuclear Chemistry Group SUNY Stony Brook, USA
PHENIX Studies of the Scaling Properties of Elliptic Flow at RHIC
energies
for the PHENIX Collaboration
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R. Lacey, SUNY Stony Brook
Why Elliptic Flow ?
• The probe for early time– The dense nuclear overlap is
ellipsoid at the beginning of heavy ion collisions
– Pressure gradient is largest in the shortest direction of the ellipsoid
– The initial spatial anisotropy evolves (via interactions
and density gradients ) Momentum-space anisotropy
– Signal is self-quenching with time
...])φ[2(2φcos211212
23
3
RRT
vvdydpNd
pdNdE
Reacti
on pl
ane
X
Z
Y
Px
Py Pz
])φ[2cos(2 Rv
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R. Lacey, SUNY Stony Brook
Resent PHENIX Elliptic Flow Data
Detailed differential measurements now available for π, K, p, φ, d, D
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R. Lacey, SUNY Stony Brook
Substantial elliptic flowSubstantial elliptic flow signals are observed for a variety of particle signals are observed for a variety of particle species at RHIC. Indication of species at RHIC. Indication of rapid thermalizationrapid thermalization? ?
RHIC Elliptic Flow Data
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R. Lacey, SUNY Stony Brook
Elliptic flow at RHIC and perfect fluid hydrodynamics Elliptic flow at RHIC and perfect fluid hydrodynamics
The v2 measurements at RHIC are in a good agreement with the predictions of ideal relativistic hydrodynamics ( rapid thermalization t< 1fm/c and an extremely small ratio of shear viscosity to entropy density η/s ).
Looking for scaling properties of elliptic flow in the data – compatible with this picture
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R. Lacey, SUNY Stony Brook
Elliptic flow: eccentricity scaling
• Ideal hydro is a scale invariant:
v2(pt,b,A)/v2(b,A)~v2(pt)• v2(b,A)/ε(b,A)~const “Integrated v2 reflects momentum
anisotropy of bulk matter and saturates within the first 3-4 fm/c just after collision” (Gyulassy,Hirano Nucl.Phys.A769:71-94,2006)
PHENIX article submitted to PRL: nucl-ex/0608033
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R. Lacey, SUNY Stony Brook
Estimation of the speed of sound Estimation of the speed of sound
<cs > ~ 0.35 ± 0.05(< cs
2 > ~ 0.12), soft EOS
v2/ε for <pT> ~ 0.45 GeV/cSee nucl-ex/0604011 for details
22v
3500 MeV/fmp
Eccentricity scaled v2 has a relatively strong dependence on sound speed
Bhalerao, Blaizot, Borghini, Ollitrault : Phys.Lett.B627:49-54,2005
<cs > - average value over the time period ~R/cs
(the time over the flow develops )
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R. Lacey, SUNY Stony Brook
Scaling breaks
Elliptic flow scales with KET up to KET ~1 GeV Indicates hydrodynamic behavior Possible hint of quark degrees of freedom become apparent at higher KET
Baryons scale together
Mesons scale together
PHENIX preliminary
= mT – m
Transverse kinetic energy scalingTransverse kinetic energy scaling
( WHY ? )( WHY ? ) 212Therm colKE KE KE m u
P
PHENIX article submitted to PRL: nucl-ex/0608033
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R. Lacey, SUNY Stony Brook
Apparent Quark number scaling Hadron mass scaling at low KET (KET < 1 GeV) is preserved.
Quark number ScalingQuark number Scaling PHENIX article submitted to PRL: nucl-ex/0608033
Consistent with quark degrees of freedom in the initial flowing matter
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R. Lacey, SUNY Stony Brook
NCQ (pNCQ (pTT/n) scaling compared to KE/n) scaling compared to KETT /n /n
KET/n scaling works for the full measured range with deviation less than 10% from the universal scaling curve NCQ- scaling works only at 20% level for pt>2 GeV/c and breakes below with clear systematic dependence on the mass
PHENIX Preliminary
NCQ- Scaling
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R. Lacey, SUNY Stony Brook
KEKETT/n scaling across collision centralities/n scaling across collision centralities
KET/n scaling observed across centralities
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R. Lacey, SUNY Stony Brook
KEKETT/n scaling and system size (AuAu/CuCu)/n scaling and system size (AuAu/CuCu)
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R. Lacey, SUNY Stony Brook
Universal Scaling of Elliptic Flow at RHIC
ε(b,A) – integral elliptic flow of charged hadrons At midrapidity v2 (pt,M,b,A)/n~ F(KET/n)*ε(b,A)?
KET - transverse kinetic energy n – number of quarks
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R. Lacey, SUNY Stony Brook
Elliptic flow of φ meson and partonic collectivity at RHIC.
φ meson has a very small σ for interactions with non-strange particles φ meson has a relatively long lifetime (~41 fm/c) -> decays outside the fireball φ is a meson but as heavy as baryons (p, Λ ) : m(φ)~1.019 GeV/c2 ; (m(p)~0.938 GeV/c2: m(Λ)~1.116 GeV/c2) -> very important test for v2 at intermediate pt ( mass or meson/baryon effect?)
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R. Lacey, SUNY Stony Brook
v2 of φ meson and partonic collectivity at RHIC
v2 vs KET – is a good way to see if v2 for the φ follows that for mesons or baryons
v2 /n vs KET/n scaling clearly works for φ mesons as well
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R. Lacey, SUNY Stony Brook
Elliptic flow of multistrange hadrons (φ, Ξ and ) with their large masses and small hadronic behave like other particles → consistent with the creation of elliptic flow on partonic level before hadron
formation
Multi-strange baryon elliptic flow at RHIC (STAR)
STAR preliminary
200 GeV Au+Au
From M. Oldenburg SQM2006 talk (STAR)
J. Phys G 32, S563 (2006)Scaling test
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R. Lacey, SUNY Stony Brook
Elliptic flow of D meson
All non-photonic electron v2 (pT < 2.0 GeV/c) were assumed to come from D decay D-> e, Pt spectrum constrained by the data Different assumptions for the shape of D meson v2(pt): pion,kaon and proton v2(pt) shapes
Measurements and simulations: Shingo Sakai (PHENIX)(See J. Phys G 32, S 551 and his SQM06,HQ06,QM06 talks for details )
Robust measurements of elliptic flow of non-photonic electrons (PHENIX)
Simulations for D meson v2(pt):
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R. Lacey, SUNY Stony Brook
Elliptic flow of D meson: Scaling test
The D meson not only flows, it scales over the measured rangeThe D meson not only flows, it scales over the measured range
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R. Lacey, SUNY Stony Brook
Shear viscosity to entropy density ratio estimateFrom R. A. Lacey et al. accepted by PRL (nucl-ex/0609025 )
(η/s) ~ (1.1-2.5)/4π
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R. Lacey, SUNY Stony Brook
Constraining /s with PHENIX datafor RAA & v2 of non-photonic electrons
• Rapp and van Hees Phys.Rev.C71:034907,2005 – Simultaneously describe PHENIX
RAA(E) and v2(e) with diffusion coefficient in range DHQ (2T) ~4-6
• Moore and Teaney Phys.Rev.C71:064904,2005 – Find DHQ/(/(+p)) ~ 6 for Nf=3
• Combining– Recall +p = T s at B=0– This then gives /s ~(1.5-3)/4– That is, within factor of 2-3 of
conjectured lower bound
PHENIX article submitted to PRL nucl-ex/0611018
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R. Lacey, SUNY Stony Brook
Au+Au
KET (GeV)
0 1 2 3 4
v 2
0.00
0.05
0.10
0.15
0.20
0.25
Moore
K K p pD
200 NNs GeV
PHENIX PRELIMINARYDATA
3~ ~ 0.52
D fmT
D-meson essentially thermal ? D-meson essentially thermal ? Re1 ~ 4laxD
M D fmT
Transport Coefficients estimate
Moore and Teaney Phys.Rev.C71:064904,2005
R. Lacey (nuc-ex/0610029)
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R. Lacey, SUNY Stony Brook
Shear viscosity to entropy density estimates from RHIC data
(η/s) ~ (1.0-3.8)/4π
S Gavin and M. Abdel-Aziz , Phys. Rev. Lett 97, 162302 (2006)
“Measuring Shear Viscosity using transverse momentum correlations”.
(η/s) ~ (1.1-2.5)/4π
R. Lacey et. al., nucl-ex/0609025 (accepted by PRL)
“Has the QCD Critical Point been Signaled by Observations at RHIC?”.
(η/s) ~ (1.5-3.0)/4π
A. Adare et. al., (PHENIX), nucl-ex/0609025 (submitted to PRL)
“Energy Loss and Flow of Heavy Quarks in Au+Au collisions at 200 GeV
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R. Lacey, SUNY Stony Brook
Summary
• Universal scaling of the flow of both mesons and baryons (over a broad transverse kinetic energy range) via quark number scaling observed.
• Development of elliptic flow in the pre-hadronization phase demonstrated
• Scaling of D meson v2 compatible with full thermalization of the charm quark observed.
• Scaled flow values allow constraints for several transport coefficients.
• Outlook: we need to find the range where scaling holds and where it breakes.
– .
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R. Lacey, SUNY Stony Brook
Elliptic Flow at SPS (Pb+Pb at 158 GeV, NA49)
The statistical errors are too large to make any statement about the scaling of elliptic flow at SPS energies
V2 of K0 (preliminary) - G. Stefanek for NA49 collaboration (nucl-ex/0611003)
v2 of p, π, Λ - C. Alt et al (NA49 collaboration) nucl-ex/0606026
C. Blume (NA49) QM2006 talk
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R. Lacey, SUNY Stony Brook
Comparison with models; RAA & v2
for non-photonic electrons (PHENIX)
Two models describes strong suppression and large v2
Rapp and Van Hees Elastic scattering -> small heavy quark relaxation time τ DHQ × 2πT ~ 4 - 6
Moore and Teaney DHQ × 2πT = 3~12
These calculations suggest that small τ and/or DHQ are required to reproduce the data.
Nucl-ex/0611018
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R. Lacey, SUNY Stony Brook
Constraining /s with PHENIX data
• Rapp and van Hees Phys.Rev.C71:034907,2005 – Simultaneously describe PHENIX
RAA(E) and v2(e) with diffusion coefficient in range DHQ (2T) ~4-6
• Moore and Teaney Phys.Rev.C71:064904,2005 – Find DHQ/(/(+p)) ~ 6 for Nf=3– Calculate perturbatively,
argue result also plausible non-perturbatively
• Combining– Recall +p = T s at B=0– This then gives /s ~(1.5-3)/4– That is, within factor of 2 of
conjectured bound
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R. Lacey, SUNY Stony Brook
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R. Lacey, SUNY Stony Brook
Eccentricity CalculationParticipant Eccentricity
PHOBOS CollaborationPRL: nucl-ex/0610037
Au+Au 200 GeVCu+Cu
200 GeV
Statistical errors only
PHOBOS CollaborationPRL: nucl-ex/0610037
Cu+Cu200 GeV
Au+Au 200 GeV