QGP hydro + hadronic cascade model: Status report Tetsufumi Hirano Dept. of Physics The Univ. of Tokyo RCNP, Oct. 29-30, 2007 TH, U.Heinz, D.Kharzeev,

QGP hydro + hadronic cascade model: Status report

Tetsufumi HiranoDept. of Physics

The Univ. of Tokyo

RCNP, Oct. 29-30, 2007RCNP, Oct. 29-30, 2007

TH, U.Heinz, D.Kharzeev, R.Lacey and Y.Nara, PLB636(2006)299; in preparationTH, U.Heinz, work in progress.

Outline

Introduction Momentum Space (elliptic flow)

Mass ordering of v2(pT) revisited Violation of mass ordering for mesons Soft EOS in CGC case?

Configuration Space (femtoscopy) Source functions from hydro + cascade 1D, 3D (rside, rout, rlong)-directions

Summary

Motivation

• To understand the QGP in H.I.C., one needs to develop a dynamical framework. • One example of agreement btw. data and theory is not sufficient. (Concerning accidental reproduction)• One needs to improve his/her model continuously toward establishment of the “observational QGP physics”.

Mechanism of Mass Ordering?

STAR white paper (’05) PHENIX white paper (’05)

Lines: Results from Ideal hydro

A Hybrid Approach: QGP hydro + hadronic cascade

0collision axis

time

Au Au

QGP fluid

Initial condition:•Transverse Glauber•Longitudinal “BGK triangle”QGP fluid:•3D ideal hydrodynamics (Hirano)•massless free u,d,s+ggas + bag const. •Tc = 170 MeV

Hadron gas:•Hadronic cascade, JAM1.09 (Nara)•Tsw = 169 MeV

hadron gasTH et al.(’06)

(1D) Bass, Dumitru (2D) Teaney, Lauret, Shuryak, (3D) Nonaka, Bass, Hirano et al.

Pseudorapidity Distribution

Tune initial parameterswith Tth = 100MeVto reproduce dN/deta.Then, switch to hadroniccascade below T=Tsw.Caveat: Rejecting in-coming particles at Tsw

pT spectra for pi, K, and p

Reasonable reproduction of yields and spectrain low pT region (pT<~1.5 GeV/c)

TH et al. (in preparation).

v2(pT) for pi, K, and p

OK!

Fail to reproduce data due to(absence of) fluctuation of geometryMiller&Snelling (’03), Bhalerao&Ollitrault(’06)Andrade et al (’06),Drescher&Nara (’07)Browniowski et al(’07)

TH et al. (in preparation).

Hydro + Cascade at Work in Forward Rapidity Regions

Adapted from S.J.Sanders (BRAHMS) @ QM2006

Origin of Mass Ordering

Mass ordering behaviorresults from hadronicrescatterings.Not a direct signal of “perfect fluid QGP”Interplay btw. ideal QGP fluid and dissipative hadron gas

TH and M.Gyulassy; TH et al. (in preparation).

b=7.2fm

b=7.2fm

Why they shift oppositely?

protonspions

pT

v 2(p

T)

v 2

<pT>

must decrease with proper timev2 for protons can be negativeeven in positive elliptic flow

TH and M.Gyulassy, NPA769,71(06) P.Huovinen et al.,PLB503,58(01);TH et al, in preparation

MESON FLOW

What happens to strangeness sector?

Additive Quark Model in Transport Codes (JAM/RQMD/UrQMD)

For cross sections without exp. data,

Expected to be very small for phi, Omega, etc.

Distribution of Freeze-Out Time

b=2.0fm

(no decay)

TH et al. (in preparation).

Early kinetic freezeout for multistrange hadrons: van Hecke, Sorge, Xu(’98)

-meson case

in pT < 1 GeV/c

Just after hadronization Final results

T = Tsw = 169 MeV

b=7.2fm b=7.2fm

TH et al. (in preparation).

Caveat: Published PHENIX data obtained in pT>~1GeV/c for mesons This is NOT obtained within ideal hydrodynamics.

What happens if -meson follows radial flow?

Of course, mass ordering is seen in hydro calculations

CGC INITIAL CONDITIONS

CGC Initial Condition

•Unintegrated gluon distributiona.la. Kharzeev, Levin, and Nardi•Gluon production via kT factorization formula •Count deposited energy in dV at (0,x,y,s), 0 = 0.6fm/c

Transverse profile: Entropy density

Longitudinal Profile:Brodsky-Gunion-Kuhn triangle

Color Glass CondensateGlauber-BGK type

sx(fm) s

x(fm)

ene.

dens

ity

ene.

dens

ity

Two Hydro Initial Conditions Which Clear the “First Hurdle”

1. CGC model Matching I.C. via e(x,y,) 2.Glauber model (as a reference) Npart:Ncoll = 85%:15%

Centrality dependence Rapidity dependence

Kharzeev,Levin, and NardiImplemented in hydro by TH and Nara

v2(Npart) from CGC + QGP Fluid + Hadronic Gas Model

Glauber: Early thermalization Discovery of Perfect Fluid QGPCGC: No perfect fluid? Additional viscosity

required in QGP

Important to understand initial conditions much better for making a conclusion

TH et al.(’06)

Adil, Gyulassy, Hirano(’06)

Large Eccentricity from CGC Initial Condition

xx

yy

Pocket formula (ideal hydro): v2 ~ 0.2 @ RHICOllitrault(’92)

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

Soft QGP EoS

Soft EOS?(equilibrium)orViscosity?(non-eq.)

Soft EoS reduces v2

as it should

Summary of flow part

A QGP fluid with hadronic rescatteringOrigin of mass ordering for v2(pT)

Radial flow effect, not “mass effect”.Violation of mass ordering for mesons

Mass ordering itself is not a direct signal of perfect fluidity! Interplay btw. QGP fluids and hadron gases.

CGC I.C. is “eccentric”. Soft EOS is needed within ideal hydrodynamics.

Femtoscopy fromHydro + CascadeFrom momentum space

to configuration space

Source Imaging

Primed in PCMS(P = 0)

Source Imaging:Inverse problem from C to D with a kernel K

No more Gaussian parametrization!

Source Imaging:Inverse problem from C to D with a kernel K

No more Gaussian parametrization!

Koonin-Pratt eq.:

Source function and normalized emission rate

(Brown&Danielewicz (’97-))

Distribution of the Last Interaction Point from Hydro + Cascade

Blink: Ideal Hydro, Kolb and Heinz (2003)

x-t x-y

px ~ 0.5 GeV/c for pions•Long tail ( decay? elastic scattering?)•Positive x-t correlation

1D Source Function from Hydro + Cascade

0.48 < KT <0.6 GeV/c0.2 < KT <0.36 GeV/c

•Angle averaged source function•Broader than PHENIX data•Almost no KT dependence PHENIX data•Significant effects of hadronic rescatterings

KT=PT/2

Omega Decay or Not?

Switch off omega decay by hand in hadronic cascade Long tail still seen. Soft elastic scattering of pions?

b=5.8fm

3D Source Function from Hydro + Cascade (preliminary!)

side out long

•Source function in PCMS•1fm-slice in each direction •0.2<KT<0.4 GeV/c, || < 0.35, +-+, --- pairs•Red: Without rescattering, Black: With rescattering•No longer Gaussian shape (Lines: Gaussian)•Broaden by hadronic rescatterings

Summary of Femtoscopy

1D- and 3D-source functions from a dynamical model (QGP hydro + hadronic cascade)Significant rescattering effects are seen.Source function is no longer Gaussian.Long tail in 1D source function is described

within hadronic rescatterings.KT dependence?

Outlook

Pair-angle dependence of source function in non-central collisions

Other pairs (K, p, ,…) correlation to investigate interaction

(with Ohnishi-san)Just get started. Many other things to

do…