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Workshop on Quark-Gluon-Plasma Thermalization August 10-12, TU Wien, Vienna, Austria. What can we learn from hydrodynamic analysis at RHIC?. Tetsufumi Hirano Dept. of Physics, Columbia Univ. T.H. and M.Gyulassy, nucl-th/0506049 T.H., Y.Nara et al ., in preparation. Outline. - PowerPoint PPT Presentation
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What can we learn from What can we learn from hydrodynamic analysishydrodynamic analysis
at RHIC? at RHIC?
Tetsufumi HiranoTetsufumi Hirano
Dept. of Physics, Columbia Dept. of Physics, Columbia Univ. Univ.
Workshop on Quark-Gluon-Plasma Thermalization Workshop on Quark-Gluon-Plasma Thermalization August 10-12, TU Wien, Vienna, AustriaAugust 10-12, TU Wien, Vienna, Austria
T.H. and M.Gyulassy, nucl-th/0506049T.H. and M.Gyulassy, nucl-th/0506049T.H., Y.Nara T.H., Y.Nara et alet al., in preparation.., in preparation.
OutlineOutline
1.1. Perfect fluidity of sQGP core and Perfect fluidity of sQGP core and highly dissipative hadronic coronahighly dissipative hadronic corona
2.2. CGC + full 3D hydro + cascadeCGC + full 3D hydro + cascade
3.3. Hydrodynamic analysis suggests Hydrodynamic analysis suggests even a signal ofeven a signal of
DECONFINEMENT?!DECONFINEMENT?!
Basis of the Basis of the AnnouncementAnnouncement
Integrated elliptic flow
NA49(’03)
PHENIX white paper
Differential elliptic flowCommon initial time in hydro ~ 0.6-1.0 fm/c
A big surprise!
Our claims:Our claims:1.1. Ideal hydrodynamics Ideal hydrodynamics
accidentally accidentally reproduces these reproduces these
data!data!2.2. Nevertheless, Nevertheless, “perfect fluidity of “perfect fluidity of
the sQGP” statement the sQGP” statement still holds. still holds.
WHY!!!???WHY!!!???
Classification of Hydro Classification of Hydro ModelsModels
Tc
QG
P p
has
eH
ad
r on
ph a
s e
Partial
Chemical
Equilibrium
EOS
Model PCE:Hirano, Teaney;
Kolb…
Model HC:Teaney, Shuryak,
Bass, Dumitru,Nonaka…
Tch
Tth
Hadronic
Cascade
Chemical
Equilibrium
EOS
Tth
Model CE:Kolb, HuovinenHeinz, Hirano…
Perfect Fluid of QGP
T
~1 fm/c
~3 fm/c
~10-15 fm/c
ideal hydrodynamics
PH
EN
IX w
hite
pa
per, N
PA
757
,184
(200
5)
Are hydro results consistent?If not, what does it mean?
elliptic flow
pT spectra
p
PartialCEPartialCE
Chem.Eq.Chem.Eq.
HadronicCascadeHadronicCascade
Differential Elliptic Flow Differential Elliptic Flow DevelopsDevelops
in the Hadron Phase?in the Hadron Phase?
T.H
. and K.T
suda (’02)
Ko
lb a
nd
Hei
nz(
’04)
Is v2(pT) really sensitiveto the late dynamics?
0.4 0.6 0.80.20 0.4 0.6 0.80.20 1.0
140MeV
100MeV
transverse momentum (GeV/c)
Mean pT is the Key
Slope of v2(pT) ~ v2/<pT> Response to decreasing Tth
(or increasing )v2
PCE
CE
v2/<pT><pT>
Generic Generic feature!feature!
Accidental Reproduction Accidental Reproduction of vof v22(p(pTT) )
pT
v2(p
T)
<pT>
v2
pT
v2(p
T)
v2
<pT>
pT
v2(p
T)
v2
<pT>
Chemical Eq.
Chemical F.O.
At hadronization
CE: increase
CFO: decrease
freezeout
1.Why mean pT behaves so differently?2. Why CE result ~ HC result?
PartialCEPartialCE
Chem.Eq.Chem.Eq.
HadronicCascadeHadronicCascade
PH
EN
IX w
hite
pa
per,
NP
A75
7,1
84
(20
05
)
Intuitive PictureIntuitive Picture
ChemicalFreezeoutChemicalFreezeout
Chemical EquilibriumChemical
Equilibrium
Mean ET decreasesdue to pdV work
For a more rigorous discussion, see T.H. and M.Gyulassy, nucl-th/0506049
MASS energy
KINETICenergy
ET per particle increases in chemical equilibrium.
This effect delays cooling of the system like a viscous fluid.
Chemical equilibrium imitates viscosity
at the cost of particle yield!!!
Chem. Eq. Imitates Viscosity!
Model PCE
Model CE
Contour(T=const.)
T() at origin
T.H
. an
d K
.Tsu
da(
’02)
<vr>(Tth)
Summary of Hydro Summary of Hydro ResultsResults
Models for
Hadron
Phasev2(pT,m)
pT
spectra
Yield
or ratio
Viscous
effectCaveat
Chemical
Equilibrium Yes Yes* No No
* P (Pbar) yields
<< exp. data
Partial
Chemical
EquilibriumNo Yes* Yes No
*Only low pT for pions
Hadronic Cascade Yes Yes Yes Yes*
*Kinetic approach•Boundary
(QGPhadron)
“No-Go theorem”Ruled out!
WINNER for hydro race at RHIC !Hybrid model (Ideal QGP fluid + dissipative hadron gas)by Teaney, Lauret, and Shuryak
The End of 50-Year-OldThe End of 50-Year-Old Ideal, Chem. Eq. Hadronic Ideal, Chem. Eq. Hadronic
FluidFluidAfter the famous Landau’s paper (1953), ideal and chemical equilibrium hadronic hydrodynamics has been exploited for along time. However, the model may notbe used when chemical freezeout happens earlier than thermal freezeoutsince it accidentally reproduces pT spectra and v2(pT)at the cost of particle yields in a way thatit imitates viscosity.
A Long Long Time Ago…A Long Long Time Ago…
…we obtain the value R (Reynolds number)=1~10…Thus we may infer that the assumption of theperfect fluid is not so good as supposed by Landau.
Digression
Summary 1Summary 1Critical data harvested at RHICCritical data harvested at RHIC1.1.Particle ratio (Particle yield)Particle ratio (Particle yield)2.2.ppT T spectraspectra3.3.vv22 AND v AND v22(p(pTT))
Nearly perfect fluidity of the sQGP coreNearly perfect fluidity of the sQGP coreANDAND
Highly dissipative hadronic coronaHighly dissipative hadronic corona
Hydrodynamic analysesHydrodynamic analyses
Results from CGC + full 3DResults from CGC + full 3Dhydro + hadronic cascadehydro + hadronic cascade
Part 2Part 2Part 2Part 2
Toward a Unified Model Toward a Unified Model in H.I.C.in H.I.C.
Pro
per
time
Transverse momentum
CGCCGC(a la KLN)(a la KLN)
Color QuantumColor QuantumFluidFluid(Q(QSS
22<k<kTT22<Q<QSS
44//22))((xx-evolution eq.)-evolution eq.)
Shattering CGCShattering CGC(k(kTT factorization) factorization)
HydrodynamicsHydrodynamics(full 3D hydro)(full 3D hydro)
Parton energy lossParton energy loss(a la Gyulassy-Levai-Vitev)(a la Gyulassy-Levai-Vitev)
HadronicHadroniccascadecascade(JAM)(JAM)
Low pLow pTT High pHigh pTT
RecombinationRecombination
Collinear factorizedCollinear factorizedParton distributionParton distribution(CTEQ)(CTEQ)
LOpQCDLOpQCD(PYTHIA)(PYTHIA)
Nuc
lear
wav
efu
nctio
nP
arto
n di
strib
utio
n
Par
ton
prod
uctio
n(d
issi
pativ
epr
oces
s?)
QG
PH
adro
nga
s
FragmentationFragmentation
(MV model(MV modelon 2D lattice)on 2D lattice)
(classical Yang-Mills(classical Yang-Millson 2D lattice)on 2D lattice)
Jet quenchingJet quenching
Intermediate pIntermediate pTT
important in forward region?Not
cov
ered
in thi
s ta
lk
Not
cov
ered
in thi
s ta
lk
T.H. and Y.Nara, PRC66(’02)041901, 68(’03)064902, 69(’04)034908, PRL91(’03)082301, NPA743(’04)305
CGC + Full 3D Hydro + CGC + Full 3D Hydro + CascadeCascade
0z
t
ColorGlassCondensate
sQGP core(Full 3DHydro)
HadronicCorona(Cascade, JAM)
c.f. Recent similar approach by Nonaka and Bass (DNP04,QM05)
vv22(() from CGC + Full 3D ) from CGC + Full 3D Hydro Hydro
+ Hadronic Cascade+ Hadronic CascadePHOBOS data:“Triangle shape”prop. to dN/dTth=100MeV:“Trapezoidal shape”Typical hydro resultTth=169MeV:Triangle shape!Just after hadronization
CGC+hydro+cascade:Good agreement!
Perfect fluid sQGP core +dissipative hadronic corona
picture works in forward region!
CGC+Hydro+Cascade CGC+Hydro+Cascade in Cu+Cu Collisionsin Cu+Cu Collisions
The effect of rescatteringis seen especiallynear midrapidity.
Predictions for LHCPredictions for LHCfrom CGC+Hydro+Cascadefrom CGC+Hydro+Cascade
•No jet components•Need to estimate systematic error from Cooper-Frye formula•Monotonic increase is consistent with previous work by Teaney et al.
Early Thermalization in Early Thermalization in Peripheral Collisions at Peripheral Collisions at
RHIC?RHIC?•CGC + hydro + cascade agreement only up to 15~20% centrality(impact parameter ~5fm)•Centrality dependenceof thermalization time?Common 0=0.6fm/c
Semi-central to peripheral collisions:Not interpreted only by hadronic dissipationImportant to understand pre-thermalization stageImcomplete thermalization? (Talk by Borghini)
Does the hydrodynamic Does the hydrodynamic agreement with experimentalagreement with experimentaldata suggest evendata suggest even DECONFINEMENT?!DECONFINEMENT?!
hydro+cascadePart 3Part 3Part 3Part 3
Viscosity and EntropyViscosity and Entropy
•1+1D Bjorken flow(Ideal)
(Viscous)
•Reynolds number
: shear viscosity (MeV/fm2)s : entropy density (1/fm3)
where
/s is a good dimensionless measureto see viscous effects.
R>>1 Perfect fluid
Iso, Mori, Namiki (1959)
What Have We Learned?What Have We Learned?T
.H. a
nd
M.G
yula
ssy
(’05
)
!•Absolute value of viscosity •Its ratio to entropy density
What makes this sudden behavior?
: shear viscosity, s : entropy density
Summary
• The sQGP core + the dissipative hadronic corona picture can be established through careful comparison of current hydro results with high precision RHIC data.• This picture is confirmed in forward rapidity region by using a “cutting edge” hybrid model (CGC + full 3D hydro + hadronic cascade).• This picture is manifestation of the sudden change of entropy density at Tc, namely deconfinement!
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