QGP hydro hadronic cascade model: Status report

1
QGP hydro hadronic cascade model Status
report

• Tetsufumi Hirano
• Dept. of Physics
• The Univ. of Tokyo

TH, U.Heinz, D.Kharzeev, R.Lacey and Y.Nara,
PLB636(2006)299 in preparation TH, U.Heinz, work
in progress.
RCNP, Oct. 29-30, 2007
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Outline

• Introduction
• Momentum Space (elliptic flow)
• Mass ordering of v2(pT) revisited
• Violation of mass ordering for f mesons
• Soft EOS in CGC case?
• Configuration Space (femtoscopy)
• Source functions from hydro cascade
• 1D, 3D (rside, rout, rlong)-directions
• Summary

3
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.

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Mechanism of Mass Ordering?
STAR white paper (05)
PHENIX white paper (05)
Lines Results from Ideal hydro
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A Hybrid Approach QGP hydro hadronic cascade
TH et al.(06)
hadron gas

• Initial condition
• Transverse ? Glauber
• Longitudinal ? BGK triangle
• QGP fluid
• 3D ideal hydrodynamics
• (Hirano)
• massless free u,d,sg
• gas bag const.
• Tc 170 MeV
• Hadron gas
• Hadronic cascade, JAM1.09
• (Nara)
• Tsw 169 MeV

time
QGP fluid
collision axis
0
Au
Au
(1D) Bass, Dumitru (2D) Teaney, Lauret, Shuryak,
(3D) Nonaka, Bass, Hirano et al.
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Pseudorapidity Distribution
Tune initial parameters with Tth 100MeV to
reproduce dN/deta. Then, switch to
hadronic cascade below TTsw. Caveat Rejecting
in- coming particles at Tsw
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pT spectra for pi, K, and p
Reasonable reproduction of yields and spectra in
low pT region (pTlt1.5 GeV/c)
TH et al. (in preparation).
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v2(pT) for pi, K, and p
Fail to reproduce data due to (absence of)
fluctuation of geometry MillerSnelling (03),
BhaleraoOllitrault(06) Andrade et al
(06),DrescherNara (07) Browniowski et al(07)
OK!
TH et al. (in preparation).
9
Hydro Cascade at Work in Forward Rapidity
Regions
Adapted from S.J.Sanders (BRAHMS) _at_ QM2006
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Origin of Mass Ordering
b7.2fm
b7.2fm

• Mass ordering behavior
• results from hadronic
• rescatterings.
• 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).
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Why they shift oppositely?
protons
pions
v2(pT)
v2
ltpTgt
pT
v2 for protons can be negative even in positive
elliptic flow
must decrease with proper time
P.Huovinen et al.,PLB503,58(01) TH et al, in
preparation
TH and M.Gyulassy, NPA769,71(06)
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f MESON FLOW
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What happens to strangeness sector?
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Additive Quark Model in Transport Codes
(JAM/RQMD/UrQMD)
For cross sections without exp. data,
Expected to be very small for phi, Omega, etc.
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Distribution of Freeze-Out Time
(no decay)
b2.0fm
Early kinetic freezeout for multistrange hadrons
van Hecke, Sorge, Xu(98)
TH et al. (in preparation).
16
f-meson case
Just after hadronization
Final results
b7.2fm
b7.2fm
T Tsw 169 MeV
in pT lt 1 GeV/c
Caveat Published PHENIX data obtained in
pTgt1GeV/c for f mesons This is NOT
obtained within ideal hydrodynamics.
TH et al. (in preparation).
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What happens if f-meson follows radial flow?
Of course, mass ordering is seen in hydro
calculations
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CGC INITIAL CONDITIONS
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CGC Initial Condition
Color Glass Condensate
Glauber-BGK type

• Unintegrated gluon distribution
• a.la. Kharzeev, Levin, and Nardi
• Gluon production via kT
• factorization formula
• Count deposited energy in dV at
• (t0,x,y,hs), t0 0.6fm/c

Transverse profile Entropy density
Longitudinal Profile Brodsky-Gunion-Kuhn
triangle
ene.density
ene.density
x(fm)
x(fm)
hs
hs
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Two Hydro Initial Conditions Which Clear the
First Hurdle
Centrality dependence
Rapidity dependence
Kharzeev,Levin, and Nardi Implemented in hydro by
TH and Nara
1. CGC model Matching I.C. via e(x,y,h)
2.Glauber model (as a reference) NpartNcoll
8515
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v2(Npart) from CGC QGP Fluid Hadronic Gas
Model
TH et al.(06)

• Glauber
• Early thermalization
• Discovery of Perfect Fluid QGP
• CGC
• No perfect fluid?
• Additional viscosity
• required in QGP

Important to understand initial conditions much
better for making a conclusion
Adil, Gyulassy, Hirano(06)
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Large Eccentricity from CGC Initial Condition
y
x
Hirano and Nara(04), Hirano et al.(06) Kuhlman
et al.(06), Drescher et al.(06)
Pocket formula (ideal hydro) v2 0.2e _at_ RHIC
Ollitrault(92)
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Soft QGP EoS
Soft EoS reduces v2 as it should
Soft EOS? (equilibrium) or Viscosity? (non-eq.)
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Summary of flow part

• A QGP fluid with hadronic rescattering
• Origin of mass ordering for v2(pT)
• ?Radial flow effect, not mass effect.
• Violation of mass ordering for f 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.

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Femtoscopy from Hydro Cascade
From momentum space to configuration space
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Source Imaging
Koonin-Pratt eq.
Primed in PCMS (P 0)
Source function and normalized emission rate
Source Imaging Inverse problem from C to D with
a kernel K No more Gaussian parametrization!
(BrownDanielewicz (97-))
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Distribution of the Last Interaction Point from
Hydro Cascade
x-y
x-t

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

Blink Ideal Hydro, Kolb and Heinz (2003)
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1D Source Function from Hydro Cascade
KTPT/2
0.48 lt KT lt0.6 GeV/c
0.2 lt KT lt0.36 GeV/c

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

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Omega Decay or Not?
Switch off omega decay by hand in hadronic
cascade ? Long tail still seen. ? Soft elastic
scattering of pions?
b5.8fm
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3D Source Function from Hydro Cascade
(preliminary!)
side
out
long

• Source function in PCMS
• 1fm-slice in each direction
• 0.2ltKTlt0.4 GeV/c, h lt 0.35, p-p, p--p- pairs
• Red Without rescattering, Black With
  rescattering
• No longer Gaussian shape (Lines Gaussian)
• Broaden by hadronic rescatterings

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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?

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Outlook

• Pair-angle dependence of source function in
  non-central collisions
• Other pairs (K, p, L,)
• LL correlation to investigate LL interaction
  (with Ohnishi-san)
• Just get started. Many other things to do