theoretical overview tetsufumi hirano department of physics the university of tokyo homepage of...

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),…




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…




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




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


Summary by Teaney


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.?


Current Data Consistent with Soft EoS (on average)!?


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




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.)


RAA for J/


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 ?













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

theoretical overview tetsufumi hirano department of physics the university of tokyo homepage of...

Documents

perfect fluidin

perfect fluidity

perfect liquid8 plenary

logos perfect liquid

hydro simulationselliptic

rhicbrahms1 talk

phobos1 talk

press release roomtoday