Perfect Fluidity of Perfect Fluidity of the Quark Gluon Plasma the Quark Gluon Plasma in Relativistic Heavy in Relativistic Heavy Ion Collisions Ion Collisions Tetsufumi Hirano Tetsufumi Hirano Department of Physics, the Department of Physics, the University of Tokyo University of Tokyo hirano @ phys.s.u-tokyo.ac.jp hirano @ phys.s.u-tokyo.ac.jp http://tkynt2.phys.s.u- http://tkynt2.phys.s.u- tokyo.ac.jp/~hirano/ tokyo.ac.jp/~hirano/ KEK-CPWS-HEAP2009 KEK-CPWS-HEAP2009
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Perfect Fluidity of the Quark Gluon Plasma in Relativistic Heavy Ion Collisions
Perfect Fluidity of the Quark Gluon Plasma in Relativistic Heavy Ion Collisions. Tetsufumi Hirano Department of Physics, the University of Tokyo hirano @ phys.s.u-tokyo.ac.jp http://tkynt2.phys.s.u-tokyo.ac.jp/~hirano/. KEK-CPWS-HEAP2009. Introduction - PowerPoint PPT Presentation
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Perfect Fluidity of the Quark Perfect Fluidity of the Quark Gluon Plasma in Relativistic Gluon Plasma in Relativistic
Heavy Ion CollisionsHeavy Ion Collisions
Tetsufumi HiranoTetsufumi HiranoDepartment of Physics, the University of TokyoDepartment of Physics, the University of Tokyo
Quark gluon plasma and relativistic heavy ion collisionsQuark gluon plasma and relativistic heavy ion collisions Time evolution of heavy ion collisionsTime evolution of heavy ion collisions Transverse collective flow Transverse collective flow
Radial flowRadial flow Elliptic flowElliptic flow
Current status of dynamical modeling in heavy ion Current status of dynamical modeling in heavy ion collisionscollisions
Summary and OutlookSummary and Outlook
Where was the Quark Gluon Plasma?Where was the Quark Gluon Plasma?
History of the UniverseHistory of the Universe
History of the matterHistory of the matter
NucleosynthesisNucleosynthesis
HadronizationHadronization
Quark Gluon PlasmaQuark Gluon Plasma(after micro seconds of Big Bang)(after micro seconds of Big Bang)
Recipes for Quark Gluon PlasmaRecipes for Quark Gluon Plasma
CompressCompressHeat upHeat up hadronic many body systemhadronic many body system
Local thermalization of the QGP is non-trivial in H.I.C.
SpectrumSpectrumRed-shifted
(CMB)Blue-shifted
(hadrons)
See, e.g., Yagi, Hatsuda, Miake, Quark-Gluon Plasma (Cambridge, 2005)
Freezeout
“Re-confinement”
Expansion, cooling
Thermalization
First contact (two bunches of gluons)
Dynamics of Heavy Ion CollisionsDynamics of Heavy Ion Collisions
Time scale10fm/c~10-23sec
Temperature scale 100MeV~1012K
Jargon: CentralityJargon: Centrality
““Centrality” characterizes a collisionCentrality” characterizes a collisionand categorizes events.and categorizes events.
central eventcentral event peripheral eventperipheral event
Participant-Spectator picture is validParticipant-Spectator picture is valid
How to Quantify CentralityHow to Quantify Centrality
PHENIX: Correlation btw. BBC and ZDC signalsPHENIX: Correlation btw. BBC and ZDC signals
NNpartpart: The number of participants: The number of participantsNNcollcoll: The number of binary collisions: The number of binary collisionsNNpartpart and N and Ncollcoll as a function of as a function of impact parameterimpact parameter
197197Au+Au+197197AuAu
NNpartpart and N and Ncollcoll
Estimated Energy Density at RHICEstimated Energy Density at RHIC
PHENIX(’05)PHENIX(’05)
c from lattice
Well above Well above cc from lattice from lattice simulations in simulations in central collision central collision at RHICat RHIC
QGP from the 1QGP from the 1stst Principle Principle
Equation of state from lattice QCDEquation of state from lattice QCD•A large number of d.o.f. are freed around TA large number of d.o.f. are freed around Tcc..•Pseudo-critical temperature TPseudo-critical temperature Tcc: ~150-200 MeV: ~150-200 MeV•Typical energy density scale of transition : ~1 GeV/fmTypical energy density scale of transition : ~1 GeV/fm33
•Not available for time evolutionNot available for time evolution
M.Cheng et al., PRD77,014511 (’08)M.Cheng et al., PRD77,014511 (’08)
TransverseTransverse**
CollectiveCollectiveFlowFlow
* “Transverse”: a direction perpendicularto the collision axis.
Time Evolution of vTime Evolution of v22 from a Parton from a Parton Cascade ModelCascade Model
b = 7.5fm
generated through secondary collisions saturated in the early stage sensitive to cross section (~1/m.f.p.~1/viscosity)
v2 is
Zhang et al.(’99) ideal hydro limit
t(fm/c)
v 2 : Ideal hydro
: strongly interactingsystem
Arrival at Hydrodynamic LimitArrival at Hydrodynamic Limit
Experimental data reach Experimental data reach hydrodynamic limit curve hydrodynamic limit curve for the first time at RHIC.for the first time at RHIC.
xx
yy
Current Status ofCurrent Status ofDynamical ModelingDynamical ModelingIn Relativistic Heavy In Relativistic Heavy
Ion CollisionsIon Collisions
•Phenomenology (hydrodynamics)
Complexity of QCDNon-linear interactions of gluons
Strong couplingMany body systemColor confinement
•Inputs to phenomenology (lattice QCD)
Strategy to Attack QGP ProblemStrategy to Attack QGP Problem•The first principle (QuantumChromo Dynamics)
•Experimental data @ Relativistic Heavy Ion Collider
200+ papers from 4 collaborationssince 2000
3D Ideal Hydro Simulation in 3D Ideal Hydro Simulation in Au+Au Au+Au Collisions with b=7.2fm @ 100 GeV/nCollisions with b=7.2fm @ 100 GeV/n
Higher quality animation is available at Caveat: Camera angle keeps changing.
H.J.Drescher and Y.Nara (2007), K.Werner et al.(2006)
Details of Initial ConditionsDetails of Initial ConditionsGlauber model•Conventional initialconditions•Announcement ofdiscovery was madein comparison ofresults from Glauberwith data.•Initial entropy distribution is prop. to Npart
Color Glass Condensate•Natural picture based on QCDat very high collisionenergies.
EPOS•Phenomenologicalimplication of partonladder ~ string. •Application to airshower simulation for high energy cosmic rays.
Hadronic afterburner•Hadronic transportmodel (JAM, UrQMD)•Kinetic theory of hadron gases includingall resonances•Switching temperatureT=160 MeV (169MeV)
Transverse PlaneTransverse Plane
QGP fluid surrounded QGP fluid surrounded by hadron gasby hadron gas
Initial conditionInitial condition
Perfect fluidPerfect fluidevolution of QGPevolution of QGP
Kinetic evolutionKinetic evolutionof hadron gasof hadron gas
xx
yy
ppTT Spectra for Pions and Protons Spectra for Pions and Protons
Hybrid model works well up to pT~1.5 GeV/c(1st order, dotted) and 2-3 GeV/c (lattice-based, solid)
Glauber/CGC + Ideal Hydro + JAM
Centrality Dependence of Elliptic FlowCentrality Dependence of Elliptic FlowDiscovery of “Large” v2 at RHIC• v2 data are comparable with (naive) hydro results for the first time.• Hadronic cascade models cannot reproduce data.
This is the first time for idealhydro at work in H.I.C. Strong motivation to develop hydro-based analysis tools.
Result from a hadronic cascade (JAM)(Courtesy of M.Isse)
TH et al. (’06).
Glauber + Ideal Hydro
Centrality Dependence of Elliptic Flow Centrality Dependence of Elliptic Flow
•1st order phase transition is unlikely from data since viscosity reduces v2 largely.•How perfect? Depends on initial model.
197Au+197Au 63Cu+63Cu
Glauber/CGC + Ideal Hydro + JAM
TH et al, (in prepation)
Effects of ViscosityEffects of Viscosity•A tiny kinetic viscosityleads to large reductionof elliptic flow coefficients.•Elliptic flow is sufficiently sensitive to constrain EoS,transport coefficients, andinitial conditions.
Figure taken from M.Luzumand P.Romatschke, arXiv:0804.4015
Glauber + Viscous Hydro
Pseudorapidity Dependence of Pseudorapidity Dependence of Elliptic Flow CoefficientElliptic Flow Coefficient
QGP only QGP+hadron fluids
QGP fluid+hadron gas
T.Hirano et al.,Phys.Lett.B636(2006)299.
Not boost invariantNot boost invariantSuppression in forward and backward rapiditySuppression in forward and backward rapidity
ppTT Dependence of Elliptic Flow Dependence of Elliptic FlowAu+Au 200 GeV
•Glauber+ Ideal hydro withlattice(-motivated) EoS +hadronic cascade•Viscosity would be needed forbetter description.
Results from EPOS Initial ConditionsResults from EPOS Initial Conditions
EPOS + Ideal Hydro + UrQMD
Reasonably reproduce rapidity dependence
K.Werner et al. (2009)
Summary & OutlookSummary & Outlook Elliptic flow pattern observed at RHIC is Elliptic flow pattern observed at RHIC is
described reasonably well by hydro-based described reasonably well by hydro-based models.models. Hydro model at work for the first time in H.I.C.Hydro model at work for the first time in H.I.C. Hadron-based kinetic theory cannot reproduce Hadron-based kinetic theory cannot reproduce
flow pattern.flow pattern. Systematic studies are undergoing:Systematic studies are undergoing:
Effects of viscosity Effects of viscosity Constraint of EOS and transport Constraint of EOS and transport coefficientscoefficients
Understanding of initial pre-thermalization stage Understanding of initial pre-thermalization stage
Pseudorapidity Dependence of vPseudorapidity Dependence of v22
=0 >0<0
•v2 data are comparable with hydro results again around =0•Not a QGP gas sQGP•Nevertheless, large discrepancy in forward/backward rapiditySee next slides
TH(’02); TH and K.Tsuda(’02); TH et al. (’06).
QGP onlyQGP+hadron
Hadron Gas Instead of Hadron FluidHadron Gas Instead of Hadron Fluid
QGP coreQGP core
A QGP fluid surrounded by hadronic gas
QGP: Liquid (hydro picture)Hadron: Gas (particle picture)
11 -(-( survival probabilitysurvival probability ))
How to Quantify CentralityHow to Quantify Centrality
Parton Distribution in Proton Parton Distribution in Proton at Small xat Small x
x 20!!x 20!!
•Gluons are dominant at Gluons are dominant at small x.small x.•Small x = High energySmall x = High energy•Hadron/Nucleus as a Hadron/Nucleus as a bunch of gluons at high bunch of gluons at high energyenergy
Bjorken x ~ Fraction of longitudinal momentum Bjorken x ~ Fraction of longitudinal momentum in protonin protonKinematics in ggKinematics in gg g g
Interplay btw. Emission and Interplay btw. Emission and Recombination at Small xRecombination at Small x
Linear effect (BFKL)Linear effect (BFKL)
Non-linear effectNon-linear effect
Figures adopted from Figures adopted from E.Iancu and R.Venugopalan, in Quark Gluon Plasma 3 (world scientific)E.Iancu and R.Venugopalan, in Quark Gluon Plasma 3 (world scientific)
Non-Linear Evolution and Non-Linear Evolution and Color Glass Condensate (CGC)Color Glass Condensate (CGC)
Rate eq.*Rate eq.*
Figures adopted from K.Itakura, talk at QM2005.Figures adopted from K.Itakura, talk at QM2005.**More sophisticated equation (BK or JIMWLK) based on QCD is solved.More sophisticated equation (BK or JIMWLK) based on QCD is solved.
small xsmall xhigh energyhigh energy
““Phase Diagram” of hadronsPhase Diagram” of hadrons
0
non
-pe
rtu
rba
tive
regi
on
dilute parton
CGC
geometrical s
calin
g
DGLAP
BFKL•Onset of CGC at RHICOnset of CGC at RHIC
•Some evidences exist.Some evidences exist.•Test of CGC at LHCTest of CGC at LHC
•How to describe How to describe perturbative CGC toperturbative CGC tonon-perturbative QGP?non-perturbative QGP?RHIC
RHIC
LHCLHC
Onset of CGC in d+Au Collisions Onset of CGC in d+Au Collisions at RHICat RHIC
BRAHMS Collaboration, white paperBRAHMS Collaboration, white paper