Current Status of QGP ideal hydrCurrent Status of QGP ideal hydro + hadronic cascade modelo + hadronic cascade model

Tetsufumi HiranoTetsufumi HiranoThe Univ. of Tokyo & LBNLThe Univ. of Tokyo & LBNL

Collaborators: Pasi Huovinen and Yasushi NaraPrepared for invited review paper in

Progress in Particle and Nuclear Physics

WPCF2010, Kiev, Sept.14-18, 2010WPCF2010, Kiev, Sept.14-18, 2010

OutlineOutline

IntroductionIntroduction Model: QGP fluid + hadronic cascadeModel: QGP fluid + hadronic cascade Results: vResults: v22, source function, source function Prediction: vPrediction: v22 in U+U collisions in U+U collisions SummarySummary

IntroductionIntroduction Main aim: Understanding RHIC data (mainly flMain aim: Understanding RHIC data (mainly fl

ow and a little femtoscopy) based on a systemow and a little femtoscopy) based on a systematic analysis with QGP perfect fluid pictureatic analysis with QGP perfect fluid picture

Set a baseline for viscous hydro calculationsSet a baseline for viscous hydro calculations After press release of perfect fluid discovery in After press release of perfect fluid discovery in

20052005 Much progress: hadronic dissipation, eccenMuch progress: hadronic dissipation, eccen

tricity fluctuation, lattice EoS, CGC initial conditricity fluctuation, lattice EoS, CGC initial condition and so on.tion and so on.

ModelModel No single model to understand heavy ion collisNo single model to understand heavy ion collis

ion.ion. Employ “cutting edge” modules as far as possiEmploy “cutting edge” modules as far as possi

bleble 3D ideal hydro3D ideal hydro Hadronic transport model, JAMHadronic transport model, JAM Lattice EoS + resonance gas in JAMLattice EoS + resonance gas in JAM Monte Carlo Glauber/KLN for initial conditionMonte Carlo Glauber/KLN for initial condition

A Hybrid Approach: A Hybrid Approach: Initial ConditionInitial Condition

0collision axis

time

AuAu AuAu

QGP fluid

hadron gasModel*

•MC-Glauber•MC-KLN (CGC)

• part, R.P.

• Centrality cut

0-10%

10-20%20-30%

…

*H.J.Drescher and Y.Nara (2007)

Initial Condition w.r.t. Participant PlaInitial Condition w.r.t. Participant Planene

Shift: (<x>,<y>)Shift: (<x>,<y>)Rotation:Rotation:

Throw a diceThrow a diceto choose to choose bb

averageaverageover eventsover events

averageaverageover eventsover events

E.g.)E.g.)NNpartpart

minmin= 279= 279NNpartpart

maxmax= 394= 394in Au+Au collisionsin Au+Au collisionsat 0-10% centralityat 0-10% centrality

Participant planeParticipant plane

Reaction planeReaction plane

partpart and and R.P.R.P.

Au+AuAu+Au Cu+CuCu+Cu

•Eccentricity enhanced due to fluctuationEccentricity enhanced due to fluctuation•Significant in small system, e.g., Cu+Cu, perpheal Au+AuSignificant in small system, e.g., Cu+Cu, perpheal Au+Au•MC-KLN > MC-Glauber *MC-KLN > MC-Glauber *

*See, Drescher and Nara, PRC 75, 034905 (2007).*See, Drescher and Nara, PRC 75, 034905 (2007).

A Hybrid Approach: A Hybrid Approach: HydrodynamicsHydrodynamics

0collision axis

time

AuAu AuAu

QGP fluid

hadron gasIdeal Hydrodynamics#

•Initial time 0.6 fm/c•Lattice + HRG EoS*

##Hirano (2002),*Huovinen and Petreczky (2010) + JAM HRGHirano (2002),*Huovinen and Petreczky (2010) + JAM HRG

A Hybrid Approach: A Hybrid Approach: Hadronic CascadeHadronic Cascade

0collision axis

time

AuAu AuAu

QGP fluid

hadron gas Interface• Cooper-Frye formulaat switching temperatureTsw = 155 MeVHadronic afterburner• Hadronic transportmodel based on kinetictheory JAM*

*Y.Nara et al., (2000)

Comparison of Comparison of Hydro+Cascade ResultsHydro+Cascade Results

with Available Datawith Available Data

ppTT Spectra: MC-Glauber Spectra: MC-Glauber

Filled: PHENIX, PRC69, 034909 (2004), Open: Hydro+cascadeFilled: PHENIX, PRC69, 034909 (2004), Open: Hydro+cascadeFrom top to bottom, 0-5, 5-10, 10-15, …, 70-80% centralityFrom top to bottom, 0-5, 5-10, 10-15, …, 70-80% centrality

(1) Absolute value of entropy, (2) soft/hard fraction (1) Absolute value of entropy, (2) soft/hard fraction = = 0.18, and (3) switching temperature T0.18, and (3) switching temperature Tswsw = 155 MeV. = 155 MeV.

ppTT Spectra: MC-KLN Spectra: MC-KLN

(1) Absolute value of saturation scale and (2) scaling (1) Absolute value of saturation scale and (2) scaling parameters parameters =0.28 and (3) switching temperature T=0.28 and (3) switching temperature Tss

ww = 155 MeV = 155 MeV

Filled: PHENIX, PRC69, 034909 (2004), Open: Hydro+cascadeFilled: PHENIX, PRC69, 034909 (2004), Open: Hydro+cascadeFrom top to bottom, 0-5, 5-10, 10-15, …, 70-80% centralityFrom top to bottom, 0-5, 5-10, 10-15, …, 70-80% centrality

vv22(N(Npartpart))

Au+AuAu+Au Cu+CuCu+Cu

MC-GlauberMC-Glauber: : Apparent reproduction. No room for QGP viscosity?Apparent reproduction. No room for QGP viscosity?MC-KLNMC-KLN::Overshoot due to larger eccentricity. How small QGP Overshoot due to larger eccentricity. How small QGP viscosity?viscosity?

ppTT>0>0 ppTT>0>0

PHOBOS, PRC72, 051901 (2005); PRL98, 242302 (2007).PHOBOS, PRC72, 051901 (2005); PRL98, 242302 (2007).

vv22(centrality)(centrality)

Au+AuAu+Au Cu+CuCu+Cu

•ppTT cut enhances v cut enhances v22 by ~10% by ~10%•STAR data in Au+Au corrected by Ollitrault et al.*STAR data in Au+Au corrected by Ollitrault et al.*•vv22 w.r.t. participant plane w.r.t. participant plane

0.15 < p0.15 < pT T < 2 GeV/c< 2 GeV/c0.15 < p0.15 < pT T < 2 GeV/c< 2 GeV/c

*J.Y.Ollitrault, A.M.Poskanzer and S.A.Voloshin, PRC80, 014904 (200*J.Y.Ollitrault, A.M.Poskanzer and S.A.Voloshin, PRC80, 014904 (2009).9).

vv22(p(pTT) for PID Particles) for PID Particles•Results based on MC-Results based on MC-Glauber initializationGlauber initialization•Mass splitting pattern OKMass splitting pattern OK•A little bit overshoot evenA little bit overshoot evenin low pin low pTT region region Centrality dependence Centrality dependence (next slide)?(next slide)?

PHENIX, PRL91, 182301 (2003)PHENIX, PRL91, 182301 (2003)

0-80%0-80%

In what follows, vIn what follows, v22(p(pTT) with MC-KLN will come soon. ) with MC-KLN will come soon. Stay tuned!Stay tuned!

vv22(p(pTT) for PID Particles: ) for PID Particles: Centrality DependenceCentrality Dependence

0-20%0-20%

20-40%20-40%

40-60%40-60%

•Hydro+cascade withHydro+cascade withMC-Glauber at workMC-Glauber at workin 0-20% centralityin 0-20% centrality•Need QGP viscosityNeed QGP viscosity•Or, need jet or Or, need jet or recombination/coalescencerecombination/coalescencecomponents?components?

PHENIX, PRL91, 182301 (2003)PHENIX, PRL91, 182301 (2003)

vv22(p(pTT) for Charged Particles: Au+Au) for Charged Particles: Au+Au

•Hydro+cascade with MC-Glauber at work in low pHydro+cascade with MC-Glauber at work in low pTT

•ppTT region at work shrinks as moving to peripheral region at work shrinks as moving to peripheral Importance of viscosityImportance of viscosity PHENIX, PRC80, 024909 (2009).PHENIX, PRC80, 024909 (2009).

STAR, PRC72, 014904 (2005). STAR, PRC72, 014904 (2005).

vv22(p(pTT) for Charged Particles: Cu+Cu) for Charged Particles: Cu+Cu

•Tendency is the same as that in Au+Au collisionsTendency is the same as that in Au+Au collisions

PHENIX, PRL98, 162301 (2007).PHENIX, PRL98, 162301 (2007).STAR, PRC81, 044902 (2010). STAR, PRC81, 044902 (2010).

Source ImagingSource Imaging

Koonin-Pratt eq.:

Inverse problemInverse problem

Source function and emission rate:Source function and emission rate:

Primed (‘) variables in Pair Center-of-Mass SystemPrimed (‘) variables in Pair Center-of-Mass System

1D Source Function for Pions1D Source Function for Pions

With hadronicWith hadronicrescattering and decaysrescattering and decays

Without hadronicWithout hadronicrescattering and decaysrescattering and decays

Non-Gaussian tail in pion source functionNon-Gaussian tail in pion source functionfrom hybrid modelfrom hybrid model

Au+Au, 0-30%Au+Au, 0-30%0.3 < k0.3 < kTT < 0.9 GeV/c < 0.9 GeV/c

Au+Au, 0-30%Au+Au, 0-30%0.3 < k0.3 < kTT < 0.9 GeV/c < 0.9 GeV/c

PHENIX, PRL103, 142301(2009)PHENIX, PRL103, 142301(2009)

1D Source Function for Kaons1D Source Function for Kaons

With hadronicWith hadronicrescattering and decaysrescattering and decays

Without hadronicWithout hadronicrescattering and decaysrescattering and decays

Non-Gaussian tail in kaon source functionNon-Gaussian tail in kaon source functionfrom hybrid modelfrom hybrid model

Au+Au, 0-30%Au+Au, 0-30%0.3 < k0.3 < kTT < 0.9 GeV/c < 0.9 GeV/c

Au+Au, 0-30%Au+Au, 0-30%0.3 < k0.3 < kTT < 0.9 GeV/c < 0.9 GeV/c

PHENIX, PRL103, 142301(2009)PHENIX, PRL103, 142301(2009)

Emission Rate for PionsEmission Rate for Pions

0-30% Au+Au, pions, 0.3 < p0-30% Au+Au, pions, 0.3 < pxx < 0.9 GeV/c < 0.9 GeV/cWithoutWithout hadronic rescattering or decays hadronic rescattering or decays Negative x-t correlationNegative x-t correlation

Emission Rate for PionsEmission Rate for Pions

0-30% Au+Au, pions, 0.3 < p0-30% Au+Au, pions, 0.3 < pxx < 0.9 GeV/c < 0.9 GeV/cWithWith hadronic rescattering and decays hadronic rescattering and decays Positive x-t correlation(?)Positive x-t correlation(?)

Emission Rate for KaonsEmission Rate for Kaons

0-30% Au+Au, 0-30% Au+Au, kaonskaons, 0.3 < p, 0.3 < pxx < 0.9 GeV/c < 0.9 GeV/cWithoutWithout hadronic rescattering or decays hadronic rescattering or decays Negative x-t correlationNegative x-t correlation

Emission Rate for KaonsEmission Rate for Kaons

0-30% Au+Au, 0-30% Au+Au, kaonskaons, 0.3 < p, 0.3 < pxx < 0.9 GeV/c < 0.9 GeV/cWithWith hadronic rescattering and decays hadronic rescattering and decays Positive x-t correlation(?)Positive x-t correlation(?)

Predictions from Predictions from Hydro+Cascade ModelHydro+Cascade Model

Collisions of Deformed Nuclei at RHICCollisions of Deformed Nuclei at RHIC

U+U collision in run12U+U collision in run12at RHIC?at RHIC?•More multiplicityMore multiplicity•Larger eccentricityLarger eccentricity•Finite eccentricity at Finite eccentricity at zero impact parameterzero impact parameterbody-body collisionbody-body collision•Unable to controlUnable to controlconfiguration configuration Need NeedMonte-Carlo study andMonte-Carlo study andevent selectionevent selection

vv22 in U+U Collisions in U+U Collisions

•vv22 increases due to deformation of colliding nuclei. increases due to deformation of colliding nuclei.•vv22// scales with transverse density. scales with transverse density.•Maximum transverse density increases only by ~10%Maximum transverse density increases only by ~10%in central U+U collisions.in central U+U collisions.

Prediction at LHCPrediction at LHC

STAY TUNEDSTAY TUNEDNew predictionsNew predictions

come in a month.come in a month.

SummarySummary Current status of hybrid approachCurrent status of hybrid approach

Elliptic flowElliptic flow MC-Glauber initialization gives a reasonable agreement MC-Glauber initialization gives a reasonable agreement

with data in very central collisions.with data in very central collisions. Results deviate from data as moving away from central Results deviate from data as moving away from central

collisions.collisions. QGP viscosity?QGP viscosity?

Source functionSource function Non-Gaussian tail is seen through hadronic rescatteringNon-Gaussian tail is seen through hadronic rescattering

s and decayss and decays U+U collisionsU+U collisions

Follow scaling behavior, extend (1/S)dNFollow scaling behavior, extend (1/S)dNchch/d/d by ~10% by ~10%

BACKUPBACKUPSLIDESSLIDES

Event Distributions from Monte CarloEvent Distributions from Monte Carlo

Centrality cut is doneCentrality cut is doneaccording to Naccording to Npartpart

Correlation btw. NCorrelation btw. Npartpart and N and Ncollcoll

Au+AuAu+Au U+UU+U

NNpartpart NNpartpart

NNco

llco

ll

NNco

llco

ll

Eccentricity FluctuationEccentricity Fluctuation

Interaction points of participants vary event by eveInteraction points of participants vary event by event.nt. Apparent reaction plane also varies.Apparent reaction plane also varies. The effect is significant for smaller system such The effect is significant for smaller system such as Cu+Cu collisionsas Cu+Cu collisions

Adopted from D.Hofman(PHOBOS),Adopted from D.Hofman(PHOBOS),talk at QM2006talk at QM2006

A sample eventA sample eventfrom Monte Carlofrom Monte CarloGlauber modelGlauber model

i

0

Event-by-Event EccentricityEvent-by-Event Eccentricity

Comparison of Source FunctionsComparison of Source Functions

Both normalized to be unityBoth normalized to be unity

Normalization in PHENIX???Normalization in PHENIX???

(fm

-2)