Transcript Document

Energy and system size
dependence in string-hadronic
models
Elena Bratkovskaya
FIAS, J.W. Goethe Universität
Frankfurt am Main
01.04.2005, Bergen
‚Little Bangs‘ in the Laboratory
Initial State
Hadronization
time
Au Au
hadron
degrees
of freedom
Quark-Gluon-Plasma ?
quarks and gluons
hadron
degrees
of freedom
How can we proove that an equilibrium QGP has been
created in central Au+Au collisions ?!
The QGP in Lattice QCD
Lattice QCD:
Quantum Cromo Dynamics
(fundamental theory of quark-gluon
interactions ):
predicts strong increase of
the energy density  at critical
temperature TC ~170 MeV
14
12
4
10
/T
 Possible phase transition from
hadronic to partonic matter
(quarks, gluons) at critical energy
density C ~1 GeV/fm3
energy density versus temperature
8
Lattice QCD:
B=0
B=530 MeV
6
4
2
0
0.5
Tc = 170 MeV
1.0
1.5
2.0
2.5
3.0
T/Tc
Z. Fodor et al., PLB 568 (2003) 73
Critical conditions - C ~1 GeV/fm3 , TC ~170 MeV - can be reached in
heavy-ion experiments at bombarding energies > 5 GeV/A
The phase diagram of QCD
250
200
T [MeV]
• UrQMD initial energy
endpoint
(2+1 flavor lattice QCD)
[Fodor, Katz '04]
endpoint
density is higher than the
boundary from LQCD
(3 flavor lattice QCD)
[Karsch et al., QM'04]
phase boundary
150
endpoint
(2+1 flavor lattice QCD)
[Fodor, Katz '02]
somewhere between 20
and 30 A GeV
100
UrQMD:
Au+Au, 11 A GeV
Pb+Pb, 40 A GeV
Pb+Pb, 160 A GeV
Au+Au, 21300 A GeV
50
•-> we are probing a new
chemical freezout
[Cleymans et al.]
phase of matter already at
AGS!
0
0
200
400
600
B [MeV]
800
1000
•Tri-critical point reached
1200
Quark condensate in central Au+Au
__
__
Au+Au, 6 A GeV (central)
1.0
30
40
0.0 10
0.5
20
1.0
0.5
0.0 10
0.5
20
30
40
20
10
0
-10
-20
1.0
0.0 10
20
30
40
20
30
z [fm]
40
0.0 10
30
40
0.0 10
30
z [fm]
40
20
40
0.5
20
30
40
20
10
0
-10
-20
0.0 10
20
30
40
z [fm]
40
20
10
0
-10
-20
0.0 10
30
40
0.0 10
20
30
40
40
time=16 fm/c
20
30
40
0.0 10
20
time=11 fm/c
0.0 10
30
0.5
20
10
0
-10
-20
30
20
10
0
-10
-20
40
time=20 fm/c
1.0
0.5
z [fm]
20
20
10
0
-10
-20
1.0
1.0
20
10
0
-10
-20
0.0 10
time=9 fm/c
time=5 fm/c
0.5
30
20
0.5
20
10
0
-10
-20
1.0
20
0.0 10
0.5
20
10
0
-10
-20
1.0
time=20 fm/c
0.0 10
30
1.0
0.5
20
0.5
20
10
0
-10
-20
time=13 fm/c
1.0
time=3 fm/c
1.0
20
10
0
-10
-20
0.0 10
time=16 fm/c
time=11 fm/c
0.5
20
10
0
-10
-20
20
0.5
20
10
0
-10
-20
1.0
0.5
0.0 10
1.0
time=5 fm/c
0.0 10
40
20
10
0
-10
-20
time=7 fm/c
1.0
0.5
time=9 fm/c
time=3 fm/c
1.0
30
20
10
0
-10
-20
x [fm
]
20
1.0
x [fm
]
0.5
20
10
0
-10
-20
time=1 fm/c
time=13 fm/c
x [fm
]
1.0
0.5
0.0 10
time=7 fm/c
x [fm
]
1.0
Au+Au, 20 A GeV (central)
x [fm
]
time=1 fm/c
__
<qq(x,0,z;t)> / <qq>V
0.5
20
30
z [fm]
40
20
10
0
-10
-20
•Quark condensate drops to zero already at lower AGS energies!
•-> we are probing a new phase of matter already at AGS!
0.0 10
20
30
z [fm]
40
20
10
0
-10
-20
x [fm
]
__
<qq(x,0,z;t)> / <qq>V
HSD calculations:
NPA 674 (2000) 249
Signals of QGP
• Strangeness enhancement
• Charm suppression
• Collective flow (v , v )
1
2
• further signals of QGP:
(not covered in this talk)
Multi-strange particle enhancement in Au+Au
Jet quenching and angular correlations
High pT suppression of hadrons
Nonstatistical event by event correlations ...
Concepts: HSD & UrQMD
HSD – Hadron-String-Dynamics transport approach
UrQMD – Ultra-relativistic-Quantum-Molecular-Dynamics
•Solution of the transport equations with collision terms describing:
 elastic and inelastic hadronic reactions:
baryon-baryon, meson-baryon, meson-meson
 formation and decay of baryonic and mesonic resonances
 string formation and decay
Implementation of detailed balance on the level of 1<->2
and 2<->2 reactions (+ 2<->n multi-meson fusion reactions in HSD)
•
•Degrees of freedom:
baryons + mesons including excited states
strings; q, qbar, (qq), (qbar qbar) (no gluons!)
HSD & UrQMD – microscopic models for heavy-ion reactions
• very good description of particle production in pp, pA reactions
• unique description of nuclear dynamics from low (~100 MeV) to
ultrarelativistic (21.3 TeV) energies
HSD
1999
predictions
4p yield
dN/dy (y=0)
+
+
p
10
10
2
E866
E895
NA49
PHENIX
BRAHMS
STAR
HSD
UrQMD 1.3
10
1
10
p
3
E895
NA49
BRAHMS
2
HSD
UrQMD 1.3
10
1
-
-
p
Particle yields
10
10
2
E895
NA49
PHENIX
BRAHMS
STAR
10
10
10
10
10
10
p
3
•
E895
NA49
BRAHMS
2
2
1
K
0
E866
NA49
PHENIX
BRAHMS
STAR
+
10
10
10
1
10
0
K
-1
10
E866
NA49
PHENIX
BRAHMS
STAR
-
-2
10
Excitation function of
p+, K+, (L+S0) yields
10
1
K
+
E866
NA49
BRAHMS
•
Reasonable description
of strangeness by HSD
and UrQMD
HSD overestimates
pions at low AGS
0
•
2
1
0
K
-1
-
E866
NA49
BRAHMS
10
UrQMD overestimates
pions at top AGS and
above
-2
10
15
90
10
0
(deviations < 20%)
60
L +S
5
0
E877
NA49
WA97
0
10
L +S
30
E877
NA49
0
0
10
1
10
2
10
3
Elab/A [GeV]
10
4
10
0
10
1
10
2
10
3
Elab/A [GeV]
10
4
PRC 69 (2004) 015202
Excitation function of K+/p+, K-/p-, (L+S0)/p ratios
+
+
K /p
y=0
0.25
4p
0.25
0.20
0.20
0.15
0.15
+
+
<K >/<p >
0.10
0.10
E866
NA49
PHENIX
STAR
BRAHMS, 5%
BRAHMS, 10%
0.05
E866
NA49
BRAHMS, 5%
0.05
0.00
0.00
10
0
10
1
10
2
10
3
10
4
0.25
10
0
10
1
2
10
10
3
4
10
0.25
-
-
-
0.20
0.20
HSD
UrQMD 1.3
0.15
0.15
0.10
0.10
0.05
E866
NA49
PHENIX
STAR
BRAHMS, 5%
BRAHMS, 10%
0.00
10
0
10
1
10
2
10
3
-
<K >/<p >
K /p
10
0.05
E866
NA49
BRAHMS, 5%
0.00
4
0.08
HSD
UrQMD 1.3
Experimental K+/p+
ratio shows a peak at
~30 A GeV -,horn‘which is not
reproduced by the
transport approaches
HSD and UrQMD !
10
0
10
1
2
10
10
3
4
10
0.08
0
0
<L+S >/<p>
(L+S ) / p
0.06
0.06
E877
NA49
STAR
0.04
0.02
E877
NA49
0.04
0.02
0.00
0.00
10
0
10
1
10
2
10
Elab/A [GeV]
3
10
4
10
0
10
1
2
10
10
Elab/A [GeV]
3
4
10
PRC 69 (2004) 015202
Transverse mass spectra - barometer of the reaction
10
C+C, 160 A GeV, 17.5%, 3.0 < y lab < 3.23
2
HSD
UrQMD
-2
1/mT dN/dmTdy [(GeV) ]
-
10
10
10
10
10
p
1
K
0
mT=(m2+pT2)1/2 – transverse mass
T - inverse slope parameter
+
-1
-
K *0.1
-2
-3
0.0
0.2
0.4
0.6
0.8
1.0
Si+Si, 160 A GeV, 12.5%, 3.0 < y lab < 3.23
10
2
-
p
HSD
UrQMD
-2
1/mT dN/dmTdy [(GeV) ]
 
1 dN
 exp - mT
T
m T dm T
10
1
K
10
• Exp. data for light systems C+C
+
0
and Si+Si at 160 A GeV are
reasonably described by HSD and
UrQMD
-
K *0.1
10
10
HSD & UrQMD 2.0:
• Transverse mass spectra of p+,
K+ from p+p and p+A collisions
are well reproduced at all energies
-1
-2
0.0
0.2
0.4
0.6
0.8
1.0
mT-m0 [GeV]
PRL 92 (2004) 032302
mT spectra for Au+Au from AGS to RHIC
10
4
10
3
10
2
10
1
10
4
10
Au+Au, 4 A GeV, 5%, midrapidity
p
-1
10
-2
10
4
10
3
10
2
10
1
10
0
-2
1/mT dN/dmTdy [(GeV) ]
-1
10
-2
10
10
3
10
2
10
1
10
K
0
10
10
-2
10
4
10
3
10
K
+
0
10
-
K *0.1
NA49
HSD
UrQMD
-1
10
-
K *0.1
-2
10
4
10
Au+Au, 6 A GeV, 5%, midrapidity
p
Pb+Pb, 40 A GeV, 7%, midrapidity
3
10
+
p
2
HSD 2.0 & UrQMD 2.0:
-
10
K
1
10
+
0
+
-
10
K *0.1
-1
Pion slopes are
only slightly underestimated
by transport
10
-
-2
10
4
10
Au+Au, 8 A GeV, 5%, midrapidity
p
3
10
+
p
Pb+Pb, 80 A GeV, 7%, midrapidity
-
2
10
1
K
-1
-
+
K *0.1
4
p
2
1
K
10
Pb+Pb, 30 A GeV, 7%, midrapidity
3
10
HSD
UrQMD
10
0
10
E866/E917
E895
+
K
+
10
+
0
10
-
--
K *0.1
-1
K *0.1
10
-2
10
4
10
2
10
1
10
0
10
Au+Au, 11 A GeV, 5%, midrapidity
p
Pb+Pb, 160 A GeV, 5%, midrapidity
3
10
+
p
-
2
K
10
+
K
-
10
-1
10
-2
10
-3
+
1
10
-
K *0.1
0
10
K *0.1
-1
10
10
3
10
2
Pb+Pb, 20 A GeV, 7%, midrapidity
p
10
1
10
0
-
3
10
K
+
10
10
-2
10
-3
0.0
p
K
-
+
1
10
-
-1
Au+Au, s =200 GeV, 5%, midrapidity
2
K *0.1
10
1/2
4
10
Kaon slopes
are too low
above 5 A GeV!
-
0
K *0.1
10
STAR
BRAHMS
PHENIX
-1
10
-2
10
0.2
0.4
0.6
mT-m0 [GeV]
0.8
1.0
0.0
0.2
0.4
0.6
0.8
mT-m0 [GeV]
1.0
PRC 69 (2004) 015202
‚Alternative‘ scenarios (HSD)
•Hadronic medium effects
should happen: but practically don‘t enhance high mT-spectra (~10%)
•String-string interaction –> overlapping strings
small effect on mT-slope with transverse string radius Rs~0.25fm
(depends on Rs)
•Isotropic decay of meson-baryon strings
inconsistent with other observables (stopping and larger meson production)
•Nonleading parton (quark/diquark) elastic scattering with s
el(qq)
=selpN/NQuark
low effect at AGS, strong at RHIC, but hadron multiplicities
become too high
• Reduced formation time t ->0 : too large hadron multiplicities
•. . .

F
In all cases the ‚improvement‘ on the mT slope is small or inconsistent
with other observables!
PRC 69 (2004) 015202
‚Alternative‘ scenarios:
High mass baryon resonances - UrQMD 2.1
UrQMD 2.1 - model in spirit of RQMD:
•
•
•
mB strings of invariant mass 2 < M < 3 GeV are replaced by quasiparticles (= high mass resonances) that decay isotropically according to the
Br of the heaviest implemented resonance with the same quantum
numbers
 light meson (p,K) emission is suppressed by ~ 25% compared to a string
of the same invariant mass
Isotropic mB elastic scattering instead of forward peaked leading hadron
scattering
Strangeness suppression factor gS has been enhanced from gS =0.3
(UrQMD 1.3 or 2.0) to 0.5 (UrQMD 2.1)  more strangeness production !

Improves T-slope, however, is inconsistent with other
observables!
PRC 69 (2004) 015202
Cronin effect at RHIC (HSD)
Cronin effect: initial state semi-hard gluon radiation increases pT
spectra already in p+A or d+A
2
1/N event

d
N dA /dydp T
dA
R dA (p T ) 
inelas
Modelling of the Cronin effect
< N coll > /σ pp
 dσ pp /dydp T
in HSD:
<kT2>AA = <kT2>PP (1+a NPrev)
NPrev= number of previous
collisions
parameter a = 0.25 – 0.4
W. Cassing, K. Gallmeister and C. Greiner,
Nucl. Phys. A 735 (2004) 277
HSD with Cronin eff
HSD without Cronin eff
.
.
Cronin effect on p, K+ mT-spectra in A+A (HSD)
-1
-2
mT dN/(dmTdy) [(GeV) ]
HSD with Cronin effect
10
10
10
10
-
p
Au+Au, 11 A GeV, 5%, midrapidity
2
1
K
+
0
-
10
10
K *0.1
-1
-2
10
10
0.2
0.6
0.8
1.0
p
-
• Substantial
hardening of the mT
spectra at RHIC –>
large improvement !
2
+
1
-
10
10
10
K *0.1
0
-1
-2
0.0
-2
-1
• Hardening of the mT
spectra at top SPS
Pb+Pb, 160 A GeV, 5%, midrapidity
3
K
10
0.4
-1
-2
mT dN/(dmTdy) [(GeV) ]
0.0
mT dN/(dmTdy) [(GeV) ]
• Very small effect at
AGS
3
10
10
10
0.2
p
3
K
2
0.4
0.6
0.8
1.0
1/2
-
Au+Au, s =200 GeV, 5%, midrapidity
• Consistent with other
observables !
default
with Cronin effect
+
1
-
10
10
K *0.1
0
-1
0.0
0.5
1.0
1.5
mT-m0 [GeV]
2.0
2.5
PRC 69 (2004) 015202
Inverse slopes T for K+ and K+
0.35
T [GeV]
0.30
Au+Au / Pb+Pb -> K +X
HSD
HSD with Cronin eff.
UrQMD 2.0
0.30
0.25
0.25
0.20
0.20
0.15
0.10
E866
NA44
BRAHMS
10
NA49
STAR
PHENIX
p+p -> K +X
+
10
100
-
T [GeV]
0.35
0.30
Au+Au / Pb+Pb -> K +X
HSD
HSD with Cronin eff.
UrQMD 2.0
0.30
0.25
0.25
0.20
0.20
0.15
0.15
0.10
E866
NA44
BRAHMS
10
s
NA49
STAR
PHENIX
100
1/2
[GeV]
-
0.35
0.10
p+p -> K +X
-
0
• In UrQMD and HSD hadronic
rescattering has only a small
impact on the kaon slope
0
exp. data:
K;
KS
FRITIOF-7.02 in HSD
UrQMD 2.0
0.15
0.10
100
+
0.35
exp. data:
K;
KS
FRITIOF-7.02 in HSD
UrQMD 2.0
• Cronin effect - initial state
semi-hard gluon radiationleads to the substantial
hardening of the mT spectra at
RHIC, however, has a very
small effect at low energies
||
• The hadron-string picture
10
100
s
1/2
[GeV]
fails?
> New degrees of freedom
(colored partons – qC, ga) are
missing ?!
PRL 92 (2004) 032302
PRC 69 (2004) 015202
Directed flow v1 & elliptic flow v2
Y
Non central Au+Au collisions :
interaction between constituents leads to a
pressure gradient => spatial asymmetry is converted
to an asymmetry in momentum space =>
collective flow
v 1 <
px - py
2
px  py
2
2
v 2 <
- directed flow
px
>
pT
2
>
- elliptic flow
V2 > 0 indicates in-plane emission of particles
Out-of-plane
dN
dN
1
1  2v1cos( )  2v 2cos(2 )  ...

dyp Tdp Td dyp Tdp T 2π
Y
In-plane
X
V2 < 0 corresponds to a squeeze-out perpendicular
to the reaction plane (out-of-plane emission)
v2 = 7%, v1=0
v2 = 7%, v1=-7%
v2 = -7%, v1=0
Directed flow v1 & elliptic flow v2 for Pb+Pb at 40 A GeV
0.2
Pb+Pb, 40 A GeV
protons
0.2
0.1
0.0
0.0
-0.1
-0.1
central
-0.2
-2
-1
0
1
2
0.2
NA49
HSD
UrQMD
0
1
2
0.05
•Too large elliptic flow v
2
at midrapidity from HSD
and UrQMD for all
centralities !
0.00
-0.1
-0.05
semi-central
-1
0
1
2
-0.10
-2
0.10
0.1
0.05
NA49
HSD
UrQMD
-1
semi-central
0
1
2
0.0
0.00
-0.1
Experimentally:
breakdown of v2 at
midrapidity !
 Signature for a first
v2
v1
0.2
-0.2
-2
-1
0.10
0.0
-0.2
-2
central
v2
v1
0.1
-0.2
-2
1 at
midrapidity not described
by HSD and UrQMD
v2
v1
0.1
•Small wiggle in v
Pb+Pb, 40 A GeV
protons
order phase transition !
-0.05
peripheral
pT < 2 GeV/c
-1
0
y
1
2
-0.10
-2
peripheral
pT < 2 GeV/c
-1
0
y
1
2
H. Stöcker, NPA 750 (2005)
E.B. et al., JPG 31 (2005)
Directed flow v1 for Au+Au at RHIC
+
0.04
• v1 is flat at midrapidity for protons, pions and
1/2
Au+Au->h +X, s =200 GeV
semi-central
v1 ()
0.02
kaons
• HSD shows slightly larger flow than UrQMD
0.00
-0.02
STAR (10-70%)
PHOBOS (6-55%)
UrQMD 1.3 (10-70%)
HSD 2.0 (10-70%)
-0.04
-5
-4
-3
-2
-1
0
1
2
3
4
5

0.10
0.10
v1(y)
1/2
0.05
1/2
Au+Au, s =200 GeV
4 fm < b < 8 fm
0.05
0.00
-0.05
Au+Au, s =200 GeV
4 fm < b < 8 fm
0.00
UrQMD 1.3 :
p
p
0
y
p
-0.05
+
K
-0.10
-5 -4 -3 -2 -1
HSD:
p
+
1
+
K
2
3
4
5
-0.10
-5 -4 -3 -2 -1
0
y
+
1
2
3
4
5
JPG 31 (2005)
Elliptic flow v2 in Au+Au at RHIC
0.3
1/2
0.06
Au+Au, s =200 GeV
charged particles
STAR
0.05
HSD, pT>2 GeV/c
0.2
0.03
<v2>
v2
0.04
0.02
PHOBOS
HSD
0.01
huge plasma pressure?!
0.1
0.00
-6
-4
-2
0
2

4
6
0.10
1/2
Au+Au, s =200 GeV
charged particles
||<1
0.08
0.0
0
100
200
300
N part
v2
0.06
• STAR data on v2 of high pT charged
0.04
hadrons are NOT reproduced in the
hadron-string picture =>
PHOBOS
HSD
0.02
0.00
0
50
100
150
200
250
300
350
400
Apart
evidence for huge plasma pressure ?!
• PHOBOS data on v2 for charged hadrons
(all pT) are underestimated in HSD by ~30%
PRC 67 (2003) 054905
W. Cassing, K. Gallmeister and C. Greiner,
Nucl. Phys. A 735 (2004) 277
Charmonium in heavy-ion collisions
D
J/Y
Y‘
cC
Dbar
‚Charmonium production versus absorption‘
Obviously: there should be ‚normal‘ nuclear
absorption, i.e. dissociation of charmonium by
inelastic interactions with nucleons of the
target/projectile
Charmonium-N dissociation cross section can be
fixed from p+A data
NA50 Collaboration: J/Y suppression in Pb+Pb
J/Y ‚normal‘ absorption
by nucleons
(Glauber model)
||
Experimental finding:
extra suppression in A+A
collisions; increasing with
centrality
Scenarios for charmonium suppression in A+A
• QGP color screening
•Comover absorption
[Matsui and Satz ’86]
[Gavin & Vogt, Capella et al.`97]:
but (!)
Lattice QCD predicts (2004):
J/Y can exist up to ~2 TC !
+
Regeneration of J/Y in QGP at TC:
charmonium absorption by low
energy inelastic scattering with
‚comoving‘ mesons (m=p,,r,...:
[Braun-Munzinger, Thews, Ko et al. `01]
J/Y+g <-> c+cbar+g
J/Y+m <-> D+Dbar
Y‘+m <-> D+Dbar
cC+m <-> D+Dbar
Meson absorption cross section –
strongly model dependent
sabsmesons ~1-10 mb
 Existing exp. data
at SPS (by NA50 Collaboration) are
also consistent with comover absorption models !
J/Y suppression in S+U and Pb+Pb at SPS
Bs(J/Y)/s(DY)|2.9-4.5
50
Models:
Comover model in the transport
approach – HSD/UrQMD
•
S+U, 200 A GeV
40
NA38
30
•
20
HSD
co-mover model
suppression in QGP
10
0
0
Bs(J/Y)/s(DY)|2.9-4.5
50
20
40
NA50 (2000):
anal. A
anal. B
anal. C
40
60
80
100
Pb+Pb, 160 A GeV
HSD
co-mover model
suppression in QGP
SCM
30
20
Comover model in the Glauber
approach:
(1) without transition to QGP:
Charmonia suppression increases
gradually with energy density
[Capella et al.]
(2) with transition to QGP:
Charmonia suppression sets in
abruptly at threshold energy
densities, where cC is melting, J/Y
is melting [Blaizot et al.]
•
10
0
0
20
40
60
80
ET [GeV]
100
120
Statistical coalescence model
(SCM) [Kostyuk et al.]
140
PRC 69 (2004) 054903
Y‘ suppression in S+U and Pb+Pb at SPS
0.020
Matrix element for
Y‘ + mesons <-> D+Dbar
B(Y')sY'/B(J/Y)sJ/Y
S+U, 200 A GeV
0.015
HSD, set 1
HSD, set 2
Set 1:
|MJ/Y|2=|McC|2=|MY‘|2=|M0|2
0.010
Set 2:
|MJ/Y|2=|McC|2=|M0|2
0.005
co-mover model
suppression in QGP
|MY‘|2= 1.5 |M0|2
0.000
0
20
40
60
80
100
0.020
B(Y')sY'/B(J/Y)sJ/Y
Pb+Pb, 160 A GeV
0.015
co-mover model
suppression in QGP
SCM
HSD, set 1
HSD, set 2
0.010
0.005
0.000
0
PRC 69 (2004) 054903
20
40
60
80
100
ET [GeV]
120
140
160
0.20 x10
-5
1/2
Au+Au, s =200 GeV, midrapidity
PHENIX:
Au+Au;
HSD
co-mover model
suppression in QGP
SCM
0.15
0.10
pp
10
-1
Time dependence of the rate
of J/Y absorption by mesons
and recreation by D+Dbar
annihilation:
1/2
Au+Au, s =200 GeV, central
10
J/Y+m->D+Dbar
D+Dbar->J/Y+m
-2
dN/dt
B(J/Y) dN/dy (y=0) per binary collision
J/Y suppression in Au+Au at RHIC
0.05
10
-3
10
-4
0.00
0
50
100
150
200
250
300
Number of participants
350
400
NDD~16
5
10
15
time [fm/c]
At RHIC the recreation of J/Y by D+Dbar annihilation is important !
New data with higher statistics are needed to clarify the nature of J/Y
suppression!
20
Y‘ suppression in Au+Au at RHIC
 Y‘ is strongly suppressed in
0.018
1/2
Au+Au, s =200 GeV, midrapidity
B(Y')sY'/B(J/Y)sJ/Y
0.016
co-mover model
suppression in QGP
SCM
HSD, set 1
HSD, set 2
HSD, set 1, all y
0.014
0.012
0.010
0.008
0.006
0.004
0.002
0.000
0
50
100
150
200
250
300
Number of participants
350
HSD at midrapidity 
recreation by D+Dbar
annihilation doesn‘t compensate
the absorption by mesons !
• Charm chemical equilibration
is not fully achieved in transport
calculations on the basis of
hadronic interactions since the
Y‘ to J/Y ratio still depends on
the matrix element for Y‘
coupling to mesons
400
• This allows to distinguish the
different scenarios of charmonia
suppression !
PRC 69 (2004) 054903
HSD: v1 of D+Dbar and J/Y from Au+Au versus pT and y at RHIC
0.04
1/2
Au+Au, s =200 GeV
b= 7 fm
0.00
-0.02
-2
-1
0.02
0
1
2
-5
-4
-3
-2
-1
0
1
2
3
4
5

1/2
Au+Au, s =200 GeV
b=7 fm, 0<y<1
D-mesons and J/Y follow roughly
the charged particle flow around
midrapidity !
0.00
-0.02
D+Dbar
J/Y
-0.04
0.0
STAR (10-70%)
PHOBOS (6-55%)
UrQMD 1.3 (10-70%)
HSD 2.0 (10-70%)
-0.04
y
0.04
0.00
-0.02
D+Dbar
J/Y
-0.04
v1 (pT)
1/2
Au+Au->h +X, s =200 GeV
semi-central
0.02
v1 ()
v1 (y)
0.02
+
0.04
0.5
1.0
1.5
2.0
2.5
3.0
3.5
pT [GeV/c]
nucl-th/0409047; PRC (2005)
HSD: v2 of D+Dbar and J/Y from Au+Au versus pT and y at RHIC
1/2
Au+Au, s =200 GeV
b=7 fm
0.06
1/2
0.06
Au+Au, s =200 GeV
charge particles
0.05
v2()
v2 (y)
0.04
0.02
0.04
0.03
0.02
0.00
-0.02
-2
-1
0
PHOBOS
HSD
0.01
D+Dbar
J/Y
0.00
1
-6
2
y
-4
-2
0

2
4
6
Collective flow
from hadronic
interactions is
too low at
midrapidity !
1/2
Au+Au, s =200 GeV
b=7 fm, 0<y<1
0.20
v2 (pT)
0.15
• HSD: D-mesons and J/Y follow the
charged particle flow > small v2 < 3%
PHENIX
STAR
• STAR data show very large collective
flow of D-mesons v2~15%!
0.10
0.05
0.00
-0.05
-0.10
0.0
=> strong initial flow of
non-hadronic nature!
D+Dbar
J/Y
0.5
1.0
1.5
2.0
pT [GeV/c]
2.5
3.0
3.5
nucl-th/0409047; PRC (2005)
AMPT model: v2 of D+Dbar from Au+Au versus pT at RHIC
• AMPT multi-phase transport model:
(B. Zhang, L.-W. Chen and C.-M. Ko)
Minijet partons from hard proceses
(ZPC- Zang‘s parton cascade)
+ strings from soft processes (HIJING)
•Parton (q, qbar) scattering cross
sections (3-10 mb)
„To describe the large electron elliptic
flow observed in available experimental
data requires a charm quark scattering
cross section that is much larger than
given by perturbative QCD“
[nucl-th/0502056]
QGP is NOT an ideal gas
as described by pQCD!
Summary I
•Collective flow signals of QGP
v2
v1
0.1
0.0
0.0
-0.1
-0.1
central
-0.2
-2
-1
0
1
0.2
0.1
NA49
HSD
UrQMD
-0.05
semi-central
-1
0
1
2
-0.10
-2
0.2
0.10
0.1
0.05
2
NA49
HSD
UrQMD
semi-central
0
1
2
v2
-1
0.00
-0.1
-0.05
peripheral
pT < 2 GeV/c
-1
0
1
y
• RHIC: v2 of charged hadrons at high pT (STAR)
2
-0.10
-2
peripheral
pT < 2 GeV/c
-1
0.3
0
y
1
STAR
HSD, pT>2 GeV/c
0.2
<v2>
STAR data on v2 of high pT charged hadrons are
NOT reproduced in the hadron-string picture
1
0.00
-0.1
-0.2
-2
0
0.05
0.0
-0.2
-2
central
-1
0.10
0.0
=> evidence for a huge plasma pressure ?!
-0.2
-2
2
v1
 signature for a first order phase transition ?!
Pb+Pb, 40 A GeV
protons
0.2
v2
small wiggle in v1 and breakdown of v2 at
midrapidity are not described by HSD and
UrQMD
Pb+Pb, 40 A GeV
protons
0.1
v1
•SPS: proton flow (NA49)
0.2
huge plasma pressure!
0.1
0.0
0
100
200
N part
300
2
Summary II
• Strangeness signals of QGP:
+
0.35
+
0.20
‚step‘
in slope T
0.15
0.10
0.05
E866
NA49
BRAHMS, 5%
HSD
UrQMD
0.25
0.20
0.15
E866
NA44
BRAHMS
0.10
0.00
10
0
10
1
2
10
10
Elab/A [GeV]
3
10
HSD
HSD with Cronin eff.
UrQMD
0.30
T [GeV]
‚horn‘
in K+/p+
+
<K >/<p >
0.25
Au+Au / Pb+Pb -> K +X
4
1
10
s
1/2
NA49
STAR
PHENIX
100
[GeV]
Exp. data are not reproduced in terms of hadron-string
picture => evidence for nonhadronic degrees of freedom
• Charm signals of QGP:
1/2
Au+Au, s =200 GeV
b=7 fm, 0<y<1
0.20
v2 (pT)
0.15
STAR experiment at RHIC observed very strong
collective flow v2 of charm D-mesons
PHENIX
STAR
0.10
=> evidence for strong nonhadronic interactions
in the very early phase of the reaction
0.05
0.00
-0.05
D+Dbar
J/Y
-0.10
0.0
0.5
1.0
1.5
2.0
pT [GeV/c]
2.5
3.0
3.5
Outlook
The Quark-Gluon-Plasma is there!
But what are the properties of this
phase ?!
Initial idea (1970 – 2003):
QGP is a weakly interacting
gas of colored but almost massless
quarks and gluons
nonperturbative colored parton gas
1000
colored parton liquid
T [MeV]
State of the art 2005:
QGP is a strongly interacting
and almost ideal „color liquid“ !
New phase diagram of QCD
100
endpoint
[Fodor, Katz '04]
UrQMD:
Au+Au, 11 A GeV
Pb+Pb, 40 A GeV
Pb+Pb, 160 A GeV
Au+Au, 21300 A GeV
chemical freezout
[Cleymans et al.]
10
0
A. Peshier, W. Cassing, PRL (2005)
200
400
600
B [MeV]
800
1000
Thanks to my coauthors
Steffen Bass
Marcus Bleicher
Wolfgang Cassing
Andrej Kostyuk
Marco van Leeuwen
Manuel Reiter
Sven Soff
Horst Stöcker
Henning Weber
Nu Xu
HSD, UrQMD - open codes:
http://www.th.physik.uni-frankfurt.de/~brat/hsd.html
http://www.th.physik.uni-frankfurt.de/~urqmd.html