Theoretical Overview Tetsufumi Hirano Department of Physics The University of Tokyo Homepage of Heavy Ion Caf é http://tkynt2.phys.s.u-tokyo.ac.jp/~hirano/hic/index.html rrent status of “perfect liquid
Jan 05, 2016
Theoretical Overview
Tetsufumi HiranoDepartment of PhysicsThe University of Tokyo
Homepage of Heavy Ion Caféhttp://tkynt2.phys.s.u-tokyo.ac.jp/~hirano/hic/index.html
--Current status of “perfect liquid”--
Outline
My personal view of “Perfect Liquid announcement” and QM2006
What’s Next?Systematic study based on the hybrid appro
ach (base line argument) Initial condition & mechanism of thermalizati
on Improvement of current hydro modelsUtilizing outputs from hydro simulations
Elliptic Flow for Charged Particles
T.H.(’01)
P.Huovinen(’03)Roughly speaking,ideal hydro gives a good description
Roughly speaking,ideal hydro gives a good description
P.Kolb et al.(’01)
TH, plenary talk @ QM2004
I did not make a conclusive statement @ QM2005
TH, plenary talk @ QM2004
An announcement was made on April 18, 2005
Behind the Press Release Room…
Today, I won’t discuss this particular topic any more.See, TH and M.Gyulassy, NPA769,71(2006).
TH, talk @ APS meeting, FL, 2005
Nothing about “press release” nor “perfect liquid”
Mystery at QM2005, Budapest (Just 4 Months after Press Release)
8 plenary talks from RHICBRAHMS(1 talk), PHENIX(3 talks),PHOBOS(1 talk), STAR(3 talks).
What happened to the press release on “perfect fluidity”?
The press release was just a dream?Two Logos (perfect liquid, sQGP) are enough?
TH, talk @ BNL, 11/04/2005
QM2006 @ Shanghai
24 plenary theory speakers+52 parallel theory speakers
(Impossible to cover all of them…)Who cares about “perfect fluid”
in this conference?
What’s Next ?
1. Systematic studies based on1. Systematic studies based onthe hybrid approachthe hybrid approach
(Glauber I.C. + perfect fluid QGP + dissipative hadron gas). HBT, source functions
System size, collision energy
2. Initial condition & mechanism2. Initial condition & mechanism of early thermalizationof early thermalization
CGC, ”Glasma” Isotropization
Instability Non-equilibrium field theory
3. Improvement of current 3. Improvement of current hydro modelshydro models
Fluctuations Constraint of EOS (Causal) Viscosity
Chemical non-equilibriumMach cone
4. Utilizing outputs from 4. Utilizing outputs from hydrodynamic simulationshydrodynamic simulations
Jet quenching (q, Q, and g) J/ transport
E&M radiation Recombination
TH, a slide prepared for YKIS06
•3D Langrangean hydro + UrQMD + Jet Quenching +…C.Nonaka(plenary), S.Bass(parallel),…•3D Eulerian Hydro + JAM + Jet Quenching +…TH(parallel), (Y.Nara),M.Isse(poster),…
1. Systematic studies based on1. Systematic studies based onthe hybrid approachthe hybrid approach
(Glauber I.C. + perfect fluid QGP + dissipative hadron gas). HBT, source functions
System size, collision energy
Current Status of Hydro+Cascade
0z
t
QGP fluid
hadronic gas
Perfect fluid QGP coreDissipative hadronic coronaTH and M.Gyulassy (2006)
Inputs of the Model
SolverFull 3D Eulerian ideal hydro + JAMInitial ConditionInitial time 0: 0.6fm/cTransverse profile: 0.85part+0.15coll
Longitudinal profile: BGK triangle (Brodsky-Gunion-Kuhn)EoSNf=3 massless ideal QGP gas+Resonance gas (up to (1232))in partial chemical equilibriumCritical temperature Tc: 170MeVChemical f.o. temperature Tch: 170MeVSwitching temperature Tsw: 169MeV
pT Spectra from QGP Fluid
+ Hadron Gas Model
A hybrid model works well up to pT~1.5GeV/c.Other components (reco/frag) would appear above.
Elliptic Flow from QGP Fluid + Hadron Gas Model
Good agreement for bulk (pT<~1.5GeV/c)
PID v2(pT) at midrapidity
O.K. in semicentral collisions
Presumably due to fluctuationMiller&Snellings(’03)
Hydro + cascade at work in forward
Adapted from S.J.Sanders (BRAHMS) @ QM2006
A Probable Scenario TH and Gyulassy (’06)
!•Absolute value of viscosity •Its ratio to entropy density
Rapid increase of entropy density canmake hydro work at RHIC.
Deconfinement Signal?!
: shear viscosity, s : entropy density
Kovtun,Son,Starinets(’05)Kovtun,Son,Starinets(’05)
Other systems?Kapusta, talk @ QM2006Csernai,Kapusta, McLerran(’06)
Something happens at TcNot driven by entropy jump…
2. Initial condition & mechanism2. Initial condition & mechanism of early thermalizationof early thermalization
CGC, ”Glasma” Isotropization
Instability Non-equilibrium field theory
Plenary•F.Gelis, QCD at small x•M.Strickland, Thermalization via instabilitiesParallel•R.Venugopalan, Multiple production to NLO in AA collisions•M.Asakawa, Anomalous viscosity of an expanding quark-gluon plasma•R.Fries, Early time evolution of high energy heavy ion collisions•Z.Xu, Parton Thermalization and Energy Loss in U.R.H.I.C within a P.C.•X.-M.Xu, Thermalization of Quark-Gluon Matter
How Do Partons Get Longitudinal Momentum to Thermalize?
Free Streaming eta=y
dN/dy
y=
dN/dy
y≈Sum of delta function Width “Thermal” fluctuation
Sheet:eta=const
22 Collisions Do Not Help!
Xu and Greiner, hep-ph/0406278
Only 22 collisions,partons are still in atransverse sheeteta~y~const.23 may help.
Time Scale of Equilibration
0
2
2
02
2
2
2
2
2
exp)()(tt
E
pt
E
p
E
pt
E
peq
ZZeq
ZZ
(t) gives the timescale of kinetic equilibration.
Adapted from Z.Xu,Talk @ QM2006
Do we really need<pz
2>~<px2>?
Caveat on Kinetic Equilibration
Static medium ≠Expanding medium
(1+1)D Bjorken case:
Do we need complete isotropy?Shear viscosity allows small deviation fromisotropic distribution
Interplay btw. Expansion and Instability
Adapted from M.Strickland,Talk @ QM2006
Instability Adapted from M.Strickland,Talk @ QM2006
3. Improvement of current 3. Improvement of current hydro modelshydro models
Fluctuations Constraint of EOS (Causal) Viscosity
Chemical non-equilibriumMach cone
Plenary•D.T.Son, AdS/CFT and QGP•D.Teaney, Experimental evidence of perfect fluididty at RHIC•J.Kapusta, The strongly interacting low viscosity matter•J.Casalderrey-Solana, Mach Cone in QGP•P.Levai, Viscosity in the strongly interacting quark matter around Tc•C.M.Ko, Parton transport description of heavy ion collisionsParallel•T.Renk, Mach cone and dijets•G.L.Ma, Two- and Three-particle Correlations in a P.C.•S.Gavin, Measuring Shear Viscosity Using pT Correlations•S.Mrowczynski, Chromo-hydrodynamics of the unstable QGP•R.S.Bhalerao, Eccentricity fluctuations and elliptic flow at RHIC•D.Molnar, Why even a small viscosity matters at RHIC•T.Kodama, New Formulation of Dissipative Relativistic Hydrodynamics
Importance of Relaxation Time
•Non-rela. (Cattaneo (’48))
0: Fourier law
: relaxation time
Heat Eq. (Parabolic Eq.) Finite relaxation time
Telegraph Eq.(Hyperbolic Eq.)
Balance Eq.
Constitutive Eq.
Violation ofcausality
cf.)杉山勝、数理科学 (2002年8月号)
Solution of Viscous Fluids
Adapted from D.Teaney,Talk @ QM2006
Be Cautious about Corrections
Adapted from D.Teaney,Talk @ QM2006
Summary by Teaney
Adapted from D.Teaney,Talk @ QM2006
Comarison btw. Hydro and Cascade
Adapted from D.Molnar, Talk @ QM2006Many caveats in this kind of comparisons!
Boltzmann at work?
~ 15 * pert !
Caveat 1: Where is the “dilute” approximation in Boltzmannsimulation? Is ~0.1fm o.k. for the Boltzmann description?Caveat 2: Differential v2 is tricky. dv2/dpT~v2/<pT>.Difference of v2 is amplified by the difference of <pT>.Caveat 3: Hadronization/Freezeout are different.
25-30%reduction
Molnar&Gyulassy(’00) Molnar&Huovinen(’04)
gluonicgluonicfluidfluid
Schematic Picture of Shear Viscosity
See, e.g. Danielewicz&Gyulassy(’85)
Assuming relativistic particles,
Perfect fluid: 0
shear viscosity 0
Gradient of flowSmearing of flow
Next time step
A New Channel to Measure Viscosity
Adapted from S.Gavin,Talk @ QM2006
Remember shear viscosity causes diffusion of flow
Correlation is broadened
Correlation fn. of pT
Adapted from S.Gavin, Talk @ QM2006
Turbulent Leads Perfect Fluid?
Adapted from M.Asakawa, Talk @ QM2006
Anomalously “Small” Viscosity
Adapted from M.Asakawa, Talk @ QM2006
“Mach Angle”
Adapted from J. Casalderrey-Solana, Talk @ QM2006
Mach “Emission” Angle Sound Velocity
Adapted from H.Stöcker, Talk @ Xi’an workshop
Dissipation Destroys Mach Cone?
Following figures taken from a talk by StöckerViscous hydro simulations by Brazil groupSee also, T.Kodama, talk @QM2006
Mach “Emission” Angle~80 Deg.?
Adapted from H.Stöcker, Talk @ Xi’an workshop
Current Data Consistent with Soft EoS (on average)!?
Adapted from H.Stöcker, Talk @ Xi’an workshop
3-Particle Correlation
Adapted from G.-L. Ma, Talk @ QM2006
Mach Cone in AMPT?
Adapted from G.-L. Ma, Talk @ QM2006
Hadronic Rescattering is not enough?
Adapted from G.-L. Ma, Talk @ QM2006Caveat: AMPT does not reproduce RAA
4. Utilizing outputs from 4. Utilizing outputs from hydrodynamic simulationshydrodynamic simulations
Jet quenching (q, Q, and g) J/ transport
E&M radiation Recombination
Plenary•P.F.Zhuang, J/ suppression and regenerationParallel•J.-e Alam, Thermal Radiation at RHIC•S.Turbide, High Momentum Dilepton Production From Jets in a QGP•J.Long, Photons and Evolution of chemically equilibrating and expanding QGP at finite baryon densityPoster•M.Isse, Jet-fluid string formation and decay in high energy H.I.C.
J/ transport in QGP fluids
Adapted from P.F.Zhuang,Talk @ QM2006
2+1D Boltzmann+suppression +regeneration
J/ transport in QGP fluids (contd.)
Adapted from P.F.Zhuang,Talk @ QM2006
RAA for J/
Adapted from P.F.Zhuang,Talk @ QM2006
Hydro Data Available
http://tkynt2.phys.s.u-tokyo.ac.jp/~hirano/parevo/parevo.html
Summary
Agreement btw. “hydro+cascade” and data indicates “Perfect Liquid”.
It is worth following up the analysis.Important to understand initial conditions.Viscous hydro as an applicable conditionConsistency among models Utilize th
e hydro data.
What’s Next ?
1. Systematic studies based on1. Systematic studies based onthe hybrid approachthe hybrid approach
(Glauber I.C. + perfect fluid QGP + dissipative hadron gas). HBT, source functions
System size, collision energy
2. Initial condition & mechanism2. Initial condition & mechanism of early thermalizationof early thermalization
CGC, ”Glasma” Isotropization
Instability Non-equilibrium field theory
3. Improvement of current 3. Improvement of current hydro modelshydro models
Fluctuations Constraint of EOS (Causal) Viscosity
Chemical non-equilibriumMach cone
4. Utilizing outputs from 4. Utilizing outputs from hydrodynamic simulationshydrodynamic simulations
Jet quenching (q, Q, and g) J/ transport
E&M radiation Recombination
BGK triangle
Adapted from A.Adil,Talk @ QM2006
Two-Particle Correlation Function
hydro, blast-wave,hydro, blast-wave,cascade, …cascade, …
relative distance dist.pair wave fn.(FSI? Coulomb?)
normalized source fn.
C2
fitting?
Source Function from 3D Hydro + Cascade
Blink: Ideal Hydro, Kolb and Heinz (2003)Caveat: No resonance decays in ideal hydro
How much the source function differs from ideal hydro in Configuration space?
Non-Gaussian Source?
x
y
px=0.5GeV/c