The importance of multiparticle collisions in heavy ion reactions C. Greiner The Physics of High...
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Transcript of The importance of multiparticle collisions in heavy ion reactions C. Greiner The Physics of High...
The importance of multiparticle collisions in heavy ion reactions
C. GreinerThe Physics of High Baryon Density
IPHC Strasbourg, Sept. 2006
Johann Wolfgang Goethe-Universität Frankfurt
Institut für Theoretische Physik
• Motivation: chemical equilibration of anti-baryons
• Equilibration by potential Hagedorn states
• Thermalization at RHIC by
• Outlook
Exploring the phases of nuclear matter
Strangeness production at SpS energies
J. Geiss
Production of Antihyperons:QGP signature…?
P. Koch, B. Müller, J. Rafelski
Production of Anti-Baryons
R.Rapp and E. Shuryak, Phys.Rev.Lett.86 (2001) 2980
C.Greiner and S.Leupold, J.Phys. G27 (2001) L95
Multimesonic channels
C.Greiner, AIP Conf. Proc. 644:337 (2003)
production at RHIC
I. Shovkovy, J. Kapusta
Thermal rates within chiral SU(3) description
Chemical population ofbaryons / anti-baryons:
P. Huovinen, J. Kapusta
Insufficient by a factor of 3 to 4
Chemical Freeze-out and of QCD
Hadronic resonance gas
vs. lattice:
(P. Braun-Munzinger, J. Stachel, C. Wetterich, Phys.Lett.B596:61-69 (2004))
Chemical equilibration of baryon / anti-baryons:
Multimesonic channels:
Possible solution by Hagedorn statesC. Greiner, P. Koch, F. Liu,
I. Shovkovy, H. Stöcker J.Phys.G31 (2005)
K. Redlich et al, K. Bugaev et al
Hagedorn gas close to
• Hagedorn spectrum:
• Hagedorn like excitations in transport models:
RQMD
HSD
Estimate for baryon/antibaryon production
Microcanonical decay of HS(Fuming Liu)
Master Equations for the decay HS→nπ+BaB
J. Noronha-Hostler
dNR (i )
dt= ¡ ¡ tot
i NR (i ) +X
n
¡ toti ;¼<i ;n(T)(N¼)nB i ! n¼
+ ¡ toti ;B ¹B <<n>¼B ¹B
i ;<n> (T)(N¼)<n>N 2B ¹B
dN¼
dt=
X
i
X
n
¡ toti ;¼nB i ! n¼
¡NR (i ) ¡ <(T)(N¼)n¢
+X
i
¡ toti ;B ¹B < n >
³NR (i ) ¡ <<n>¼B ¹B
i ;<n> (T)(N¼)<n>N 2B ¹B
´
dNB ¹B
dt= ¡
X
i
¡ toti ;B ¹B
¡N 2
B ¹B N <n>¼ <i ;<n>(T) ¡ NR (i )
¢
(1)
dNR (i )
dt= ¡ ¡ tot
i NR (i ) +X
n
¡ toti ;¼<i ;n(T)(N¼)nB i ! n¼
+ ¡ toti ;B ¹B <<n>¼B ¹B
i ;<n> (T)(N¼)<n>N 2B ¹B
dN¼
dt=
X
i
X
n
¡ toti ;¼nB i ! n¼
¡NR (i ) ¡ <(T)(N¼)n¢
+X
i
¡ toti ;B ¹B < n >
³NR (i ) ¡ <<n>¼B ¹B
i ;<n> (T)(N¼)<n>N 2B ¹B
´
dNB ¹B
dt= ¡
X
i
¡ toti ;B ¹B
¡N 2
B ¹B N <n>¼ <i ;<n>(T) ¡ NR (i )
¢
(1)
12 1
2
12 a
b
f (x;y) =
(x + 1 if y = 0xy if y 6= 0
dNR(i)/dt=-iNR(i)+ni, < i,n(T) (N)nBi! n+i,BaB<i,<n>BaB (T)(N )<n> N2BaB
dN /dt=i ni,nBi! n(NR(i)-< (T) (N )n)+i i,BaB<n>(NR(i)-<i,<n>BaB(T)(N )<n>N2BaB)
dNBaB/dt=-ii,BaB(NBaB2 N
<n> < i,<n>(T)-NR(i))
Considering the decay HS→nπ
HS→nπ+BaB
Nπ (t=0)=EquilibriumNRes(t=0)=0
Nπ (t=0) =EquilibriumNRes(t=0)=Equilibrium
HS→nπ+BaB when the Hagedorn Resonances start at twice equilibrium values and the rest starts at zero.
HS→nπ+BaB when the Hagedorn Resonances start at twice equilibrium values and the rest starts at equilibrium.
The strange sector of baryons/antibaryons
Importance of baryonic HS CBM?
The order and shape of QGP phase transitionnucl-th/0605052, I. Zakout, CG and J. Schaffner-Bielich
)4(~),( ][)2( Bvmemcvm BHTm
density of states:
4
1
)( B
Thermalization at RHIC
elliptic flow --- `early signature´ of QGP
...)2cos2cos21( 211
22 vv
dydp
dN
dyddp
dN
T
h
T
h
evidence for an early buildup of pressure anda fast thermalization of the quark-gluon system
• How can one describe the fast thermalization by the partonic collisions? • How can one understand the hydrodynamical behavior by the partonic collisions?
),(),(),( pxCpxCpxfp ggggggggg
transport simulation: on-shell parton cascade
solving the Boltzmann-equations for quarks and gluons
new development(Z)MPC, VNI/BMS
Z. Xu and C. Greiner, PRC 71, 064901 (2005)
Initial production of partons
dt
dpxfxpxfxK
dydydp
d cdab
tbtadcbat
jet
),(),( 2
222
11,;,21
2
minijets
string matter
Stochastic algorithm P.Danielewicz, G.F.Bertsch, Nucl. Phys. A 533, 712(1991)A.Lang et al., J. Comp. Phys. 106, 391(1993)
for particles in 3x with momentum p1,p2,p3 ...
collision probability:
23321
3232
32323
32222
)(823
32
22
x
t
EEE
IPfor
x
tvPfor
x
tvPfor
rel
rel
)()2(2)2(2)2(2
1'2'1321
)4(42
'2'1123'2
3'2
3
'13
'13
32 pppppME
pdE
pdI
cell configuration in space
3x
LPM
DDggggg
Dgggg
mqkk
qg
mq
sgM
mq
sgM
222
22
222
242
222
242
)(
12
)(2
9
,)(2
9
parton scatterings in leading order pQCD
the central region:: [-0.5:0.5] and xt < 1.5 fm
thermalization and hydrodynamical behavior
NO thermalization and free streaming
including ggggg without ggggg
transverse energy at y=0 in Au+Au central collision
elliptic flow in noncentral Au+Au collisions at RHIC:
central
peripheral
Comparison with RHIC data
Conclusions and Outlook• Potential Hagedorn states as additional dof can explain
and also strange baryon production close to ; (re-)population and decay are governed by detailed balance
• Three main assumptions:(1):
(2):
(3): microcanonical statistical decay
• Multiparticle interactions also important for very high energies ( )
• Future: Embedding into UrQMD
CERES
Nonequilibrium dilepton productionSpectral function of the ρ-meson:
free ρ in-medium
→ quantum “off-shell”-transport description
(B. Schenke)
Non-equilibrium dilepton production rate:
Evolving spectral function and dilepton rate
Contributions to the rate at time τ at constant energy ω
B. Schenke, C. Greiner, Phys.Rev.C73:034909 (2006)
Dilepton yields from fireball (B. Schenke)
0.0 0.2 0.4 0.6 0.8 1.0
0.5
1.0
1.5
2.0
2.5
3.0
dN
/dM
[10
-3 G
eV
-1]
M [GeV]
Dynamic Markov
Dropping mass scenario integrated over momenta:
Dropping mass (linearly in time) and resonance coupling scenarios for k=0:
B. Schenke, C. Greiner, Phys.Rev.C73:034909 (2006)
B. Schenke, C. Greiner, arXiv:hep-ph/0608032 (2006)