Collective Flow and HBT Radii from a Full 3D Relativistic Hydrodynamic Model

1
Nov.5-6, 2002
CNS/RIKEN Joint International Workshop Physics of
QCD Many Body Systems --Future perspective based
upon RHIC --
A dynamical approach to jet quenching in
relativistic heavy ion collisions Tetsufumi
Hirano Physics Department, University of Tokyo

• Outline
• Introduction Motivation
• 3D Hydro Results
• The hydrojet model
• Results_at_130A GeV
• Results_at_200A GeV
• Summary

Collaborator Yasushi Nara (Univ. of Arizona)
References T.Hirano and Y.Nara, Phys. Rev. C
66, 041901(R) (2002).
2
Introduction Motivation

• Hard components can fill in
• the difference between the data
• and the hydro result.

• A recent result from hydro
• with early chemical freeze-out
• ?pT slope is insensitive to Tth.
• T.Hirano and K.Tsuda,
  nucl-th/0205043
• (PRC, in press).

• The HydroJet Model
• (as a dynamical tool to analyze jet quenching)
• Soft Full 3D hydrodynamics
• (with early chemical f.o.)
• Hard pQCD with parton energy
• loss

pT spectra, RAA(pT) and C2(Df) in moderate high
pT (2-10 GeV/c) _at_RHIC
AuAu 130A GeV (central)
3
3D Hydro
4
Brief Summary of Our Hydro Results

• Full 3D hydro!
• No Bjorken scaling ansatz
• No cylindrical symmetry
• (t, hs, x, y) coordinate

130AGeV
T.Hirano, Phys.Rev.C65(2002)011901.

• Suppression of radial, elliptic
• flow and HBT radii in comparison
• with the conventional hydro results.

130AGeV
T.Hirano and K.Tsuda, nucl-th/0205043 (Phys.Rev.C,
in press).
5
Brief Summary of Our Hydro Results (contd.)
suppression
PHENIX 130A GeV data

• Suppression of radial flow
• as a result of chemical
• non-equilibrium properties

• pT slopes become
• insensitive to Tth.
• ?Need hard components

Tch
6
Why jets at RHIC and LHC?
Our definition of a jet A parton with pTgt2 GeV/c
just after a collision (often called mini-jet)
SPS
LHC
RHIC
PbPb_at_20A GeV sin 32 mb sjet 0.1 mb Ncoll
923 (b2 fm) ? 3 jets/event
AuAu_at_200A GeV sin 40 mb sjet 20 mb Ncoll
1067 (b2 fm) ?500 jets/event
PbPb_at_5500A GeV sin 90 mb sjet 90 mb Ncoll
2600 (b2 fm) ?2600 jets/event
Copious jets at RHIC and LHC! ? Need contribution
from jets
ppPYTHIA with CTEQ5LK factor(K2), AAstandard
Woods-Saxon nuclear density
7
Hydro Jet
8
The HydroJet Model
3D Hydro
PYTHIA
hadrons
PYTHIA
3
UA1 ppbar 200 GeV
Fragmentation Independent Fragmentation Model
x1fa
x2fb
4
PDF Collinear CTEQ5LO kT Gaussian
ltkT2gt1GeV2/c2
hadrons
PHENIX pp 200GeV
Parton energy lossdE/dx (I will discuss later)
Initial and final state radiation are included.
9
Time Evolution in the HydroJet Model
Particle spectra through Cooper- Frye formula
Hydro evolution
Full 3D hydro
t
t0
tf
0.6fm/c
10fm/c
0
Free streaming
Fragmentation
Energy loss
Jets

• Formation time0 fm
• For jets with pTgt2GeV/c,
• 1/pTlt0.1fm/cltlt1fm/c
• Momentum dist. from
• PYTHIA ver. 6.2

• Thermalization time
• Initial time of fluids
• Initial parameters in hydro have been already
  tuned.

• After hydro simulation, all survival jets
  fragment into hadrons.
• We neglect interaction of fragmented hadrons.

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Jets and Hydro Evolution in the Transverse Plane
AuAu 200AGeV, b8 fm transverse plane_at_midrapidity
r (fm-3)
Gradation ? Themalized parton density Plot (open
circles) ? Jets (pTgt2GeV/c)
y (fm)

• Initial configuration of jets
• Prop. to of binary collisions
• Assuming jets move along
• straight paths
• (eikonal approximation)

x(fm)
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Phenomenological Parton Energy Loss

• Incoherent Model

e energy deposit per scattering l mean free
path s parton-parton cross section r
thermalized parton density
From hydro simulation
Neglecting energy loss in the hadron phase.
partonic medium
e
e
e
e
Jet
l
12
Results _at_130AGeV 200AGeV
13
p0 Spectra in sNN1/2130 GeV Central Collisions

• ltdE/dxgt0.85 GeV/fm
• _at_t00.6 fm/c
• Onset of hard component
• pT1.5 GeV/c

HIJING dE/dx 0.25 (GeV/fm)
the best fit value
X.-N. Wang, NPA698(2002)296c
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Models for Parton Energy Loss

• Incoherent model

• Coherent (LPM) model

A model motivated by a) GLV 1st order, or b)
BDMPS for EgtEcr
, a free (adjustable) parameter
Transport coefficient q
LRAu m0.5 GeV/c
M.Gyulassy et al., Nucl.Phys.B571(2000)197
R.Baier et al., Nucl.Phys.B483(1997)291.
15
Suppression Factor (PHENIX)
0-10 Central
(Ncoll97594)
RAA(2 GeV/c) 0.45
RAA(8 GeV/c) 0.16
From D. dEnterria, talk at QM2002.
16
Suppression Factor in sNN1/2200 GeV Central
Collisions

• Suppression factor RAA
• Incoherent model increase
• Coherent model almost flat

• Experimental data (PHENIX)
• ? gradually decrease

RAA(pT) depends on the models of parton energy
loss.
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Back-to-Back Correlations of High pT Hadrons
pp
AA
STAR
6
Associated particles
Triggered particles
pT (GeV/c)
4
2
0.7
-0.7
0
h
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Back-to-Back Correlation (STAR)
4ltpt(trig)lt6 GeV/c data
Central 0-5
Peripheral 60-80
From D.Hardtke, talk at QM2002.
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RAA and C2 in sNN1/2200 GeV Central Collisions

• Near-side jets
• Almost independent
• Away-side jets
• Depend on magnitude of
• energy loss

We fail simultaneous reproduction of RAA and
C2. ?Need another mechanism
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Surface Emission Dominance ?
Initial positions of jets which survive at final
time
DE0
DE0.25qLeff2
DE1.0qLeff2
Completely
Partially
An interesting signature may be events in which
the hard collision occurs near the edge of the
overlap region, with one jet escaping without
absorption and the other fully absorbed.
--J.D.Bjorken, FERMILAB-Pub-82/59-THY (1982).
21
Summary

• We construct the HydroJet model as a
• dynamical approach to the physics of jet
• quenching.
• AuAu 130AGeV
• The onset of hard contribution
• ?pT1.5 GeV/c for pions
• ltdE/dxgt0.2 GeV/fm
• ( HIJING0.25 GeV/fm)
• ltdE/dxgt0.85 GeV/fm _at_t00.6 fm/c for
• incoherent model

22
Summary (contd.)

• AuAu 200AGeV
• RAA(pT) is sensitive to the model dE/dx.
• No parameter which reproduces RAA(pT)
• and the disappearance of b-to-b correlation
• simultaneously.
• ? Need other mechanisms (deflection of
• jets?)
• (Partial?) surface emission of jets may
• happen in central collisions.

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Thank you very muchfor your kind attention
24
Spare Slides
25
Suppression Factor in sNN1/2130 GeV Central
Collisions
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Jet Quenching Ratein 130A GeV Collisions
N(t)/N(t0)_at_5GeV/c

• r prop. to 1/t

• One should check LPM case

27
Comparison with Results by E.Wang and X.N.Wang

• Our result (b3.35 fm)
• dE/dx0.06r GeV/fm
• ltr(t0.6 fm/c)gt14 fm-3 ?0.85 GeV/fm
• r(t0.6 fm/c)max30 fm-3 ?1.7 GeV/fm

• Wang and Wang (R6 fm)
• dE/dx0.34(2R/t0)lnE/ln5
• For 10 GeV parton,
• dE/dx7.3 GeV/fm_at_t00.2fm/c
• For 4 GeV parton,
• dE/dx2.1 GeV/fm_at_t00.6fm/c

The differnece comes from initial time,
density profile energy dependence, and
impact parameter. Our result is consistent
with Wang and Wang result.
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Hydro_at_200GeV

• E040000MeV/fm3
• Flat region hflat4.0
• Width hGauss0.8
• Binary collision scaling
• in transverse plane

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Relative PseudorapidityDependence of Jets

• Dhlt0.5
• Clear peak at Df0
• 0.5ltDhlt1.4
• No peak at Df0

30
Intrinsic kT of Partons in Nuclei?
collinear
intrinsic kT

• Gaussian primordial kT distribution
• of partons

• Back-to-back correlation of jets
• Energy loss (0.25qLeff2)
• intrinsic kT

Intrinsic kT is not the origin of disappearance
of back-to-back correlation!
Triggered 4ltpTlt6 GeV/c, Associated 2ltpTltpT,trig
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Discussions

• Many observables to be analyzed
• v2 in high pT region
• pT spectra for (anti-)protons
• RAA(pT) in non-central collisions
• (RAA really scales with Npart ?)
• Jet quenching in off midrapidity region
• and so on
• Many effects to be included
• Deflection of jets in medium
• Interaction between fragmented
• hadrons and thermalized hadrons
• (?hydrojethadronic cascade model ?)