Flow and Femtoscopy from QGP Hydro + Hadronic Cascade

Tetsufumi HiranoDept. of Physics

The Univ. of Tokyo

WPCF, Aug. 1-3, 2007WPCF, Aug. 1-3, 2007

Outline

Part 1Mass ordering of v2(pT) revisitedViolation of mass ordering for mesons

Part 2Source functions from hydro + cascade1D3D (rside, rout, rlong)-directions

Summary

TH, U.Heinz, D.Kharzeev, R.Lacey, and Y.Nara (in preparation)

Is Mass Ordering of v2(pT) a Direct Signal of Perfect Fluidity?

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

Lines: Results from Ideal hydro

Motivation

To understand the QGP in H.I.C., need to understand the hadronic stage since

Indispensable to disentangle theseeffects for understanding of unknowns.

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”

TH et al. (in preparation).

b=7.2fm

b=7.2fm

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.

Summary of flow part

A QGP fluid with hadronic rescatteringReproduction of v2(pT,m)

A hybrid model works well.

Origin of mass ordering of v2(pT)

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

Mass ordering itself is not a direct signal of perfect fluidity!

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

1D Source Function from Hydro + Cascade (contd.)

KT dependence Centrality dependence

Almost no KT dependence Sensitive to impact parameter

lambda=1.00.2< KT <0.36 GeV/c

b=5.8fmlambda = 1.0

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, …)Just get started. Many other things to

do…