Flow and Femtoscopy from QGP Hydro + Hadronic Cascade Tetsufumi Hirano Dept. of Physics The Univ. of Tokyo WPCF, Aug. 1-3, 2007 WPCF, Aug. 1-3, 2007
Dec 21, 2015
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).
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
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!
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?