完全流体完全流体 QGPQGPはは見つかったか？見つかったか？

Tetsufumi HiranoTetsufumi Hirano

平野哲文平野哲文Institute of Physics, University of TokyoInstitute of Physics, University of Tokyo

東大総文東大総文Collaborators: U.Heinz, D.Kharzeev, R.Lacey, and Y.NaraCollaborators: U.Heinz, D.Kharzeev, R.Lacey, and Y.Nara

日本物理学会 2006年秋季大会於奈良女子大学

OutlineOutline

• Discovery of Perfect Liquid QGP

• Basis of Announcement

• Three Inputs in Hydrodynamic Models

• Sensitivity of Assumptions to v2 in Hydro

– Freezeout– Initial condition

• v2 from CGC initial conditions

• Summary and Outlook

““RHIC serves the perfect liquid”RHIC serves the perfect liquid”

http://www.bnl.gov/bnlweb/pubaf/pr/PR_display.asp?prID=05-38

Basis of the AnnouncementBasis of the AnnouncementPHENIX(’03)STAR(’02)

Multiplicity dependencepT dependenceand mass ordering

Hydro results: Huovinen, Kolb, Heinz,…

Three Inputs for Hydrodynamic Three Inputs for Hydrodynamic ModelsModels

Final stage:• Decoupling prescription

Intermediate stage:• Equation of State, P(e,n)

Initial stage:• Initial energy/entropy density distribution• Initial time

0z

t

Important to check the sensitivity of the above assumptions to final results

Sensitivity of Different Assumptions Sensitivity of Different Assumptions in Early/Late Stagesin Early/Late Stages

??Gradual

freezeout(Hadronic rescattering)

?Discovery of

“Perfect Liquid”Sudden

freezeout

Color Glass Condensate

Glauber-typeInitialInitialConditionCondition

FreezeoutFreezeout

Consistency?Consistency?Elliptic flow Particle ratio

Issue: Conventional ideal hydro could not reproduce particle ratio.Solution: Introduction of chemical freezeout in hydro.

Interpretation: Accidental reproduction by ideal hydro. Necessity of dissipation in the hadron phase.

TH and M.Gyulassy(’06)

N.Arbex et al.(’01), TH and K.Tsuda(’02), D.Teaney(’02)

Hyd

ro:

P.H

uovi

nen

Dat

a: P

HE

NIX

PH

EN

IX w

hite paper

Highlights from a Hydro+Cascade Model Based on Glauber-type Initial Conditions

TH et al.(’06); in preparation.

Sensitivity of Different Assumptions Sensitivity of Different Assumptions in Early/Late Stages in Early/Late Stages

?Discovery of Perfect fluid QGP & hadronic

corona

Gradual

freezeoutHadronic rescattering

?Discovery of

“Perfect Liquid”Sudden

freezeout

Color Glass Condensate

Glauber-typeInitialInitialConditionCondition

FreezeoutFreezeout

Two Initial Conditions Which Clear Two Initial Conditions Which Clear the First Hurdle the First Hurdle

•Glauber model Npart:Ncoll = 85%:15%•CGC model Matching I.C. via e(x,y,)

Centrality dependence Rapidity dependence

vv22(N(Npartpart) from ) from

QGP Hydro + Hadronic CascadeQGP Hydro + Hadronic Cascade

Glauber: Early thermalization Mechanism? CGC: No perfect fluid? Additional viscosity

is required in QGP

Importance of better understanding of initial condition

TH et al.(’06)

Large Eccentricity from CGC Initial Large Eccentricity from CGC Initial ConditionCondition

xx

yy

Pocket formula (ideal hydro): v2 ~ 0.2 @ RHIC energies

Ollitrault(’92)

Hirano and Nara(’04), Hirano et al.(’06)Hirano and Nara(’04), Hirano et al.(’06)Kuhlman et al.(’06), Drescher et al.(’06)Kuhlman et al.(’06), Drescher et al.(’06)

Summary and OutlookSummary and Outlook

• Much more studies needed for initial states• Still further needed to investigate EOS

dependence• To be or not to be (consistent with hydro),

that is the question!

FAKE!FAKE!