Post on 26-Mar-2015
Constraining nuclear symmetry energy from high-energy heavy-ion
collisions
Zhao-Qing Feng (冯兆庆 )
Institute of Modern Physics, Lanzhou, Chinese Academy of Sciences (CAS)
Outline
Introduction
Lanzhou Quantum Molecular Dynamics
(LQMD) model
Particle production in LQMD model
Probing equation of state (EOS) and
symmetry energy by heavy-ion collisions in
the region of 1 A GeV
Summary
2
Promising probes of the Esym(ρ) in Nuclear Reactions B.A. Li, L.W. Chen, C.M. Ko, Phys. Rep. 464(2008) 113-281
Introduction
3
L.W. Chen, C.M. Ko, and B.A. Li PRC72,064309 (2005); PRC76, 054316 (2007)
4
Z.H. Li et al., PRC74, 047304(2006) Dieperink et al., PRC68, 064307(2003)
IBUU04
Different symmetry energies used in transport models
5
LQMD
Lanzhou-Quantum-Molecular- Dynamics (LQMD) project
Dynamics of low-energy heavy-ion collisions (dynamical interaction potential, barrier distribution, neck dynamics, fusion/caption excitation functions etc)
Isospin physics at intermediate energies (constraining symmetry energy at sub or supra saturation densities in HICs)
Medium effects in heavy-ion collisions and proton induced reactions (probing the in-medium NN elastic and inelastic cross sections, properties of resonances (1232), N*(1440), N*(1535)) and mesons such as , kaons , )
Dilepton production (e+e-) at near threshold energies in heavy-ion collisions and proton induced reactions.
6
Lanzhou Quantum Molecular Dynamics (LQMD)
7
Refs: NPA750(2005)232, NPA802(2008)91, PRC80(2009)037601, PLB683(2010)140, PRC82(2010)044615, 82(2010)057901
momshloccoul UUUUU int
rr dloc
U Vloc
23/5
0
3/8
2
0
2
00
1
0
2
)(
)]([2212
potsym
pn
isosursur
Eg
gglocV
Evolution of baryons (nucleons and resonances )
Symmetry energy per nucleon in the LQMD model is derived from the Skyrme energy-density functional
with Cpot=38 MeV, a=37.7 MeV, b=-18.7 MeV which gives the Esym=31.5 MeV at =0=0.165
8
More clearly compared with other transport models, e.g., IBUU04, RBUU, SMF etc
2
00
3/22
2
2
3
23
1)(
ba
mEsym
Channels of kaon production near threshold
Energies:
B(N, ), K(K0, K+), Kb(Kb0,K-), Y(, -, 0, +)
BBBYK, BBBBKKb, BYK, BNKKb,
YNKb, NKbY, YNKbNN
Reaction channels for pion production: (1232), N*(1440), N*(1535)
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NN elastic and inelastic cross sections (Z.-Q. Feng and G.-M. Jin, Chin.Phys.Lett. 26 (2009) 062501)
10
11
Evolution of nucleons, resonances and pions calculated by LQMD197Au+197Au, 1A GeV
-20 -10 0 10 20-10
-5
0
5
10
-15 -10 -5 0 5 10 15-15
-10
-5
0
5
10
15t=0 fm/c t=20 fm/c
-20 -10 0 10 20-10
-5
0
5
10t=10 fm/c
t=15 fm/c
-15 -10 -5 0 5 10 15-15
-10
-5
0
5
10
15t=25 fm/c
-20 -10 0 10 20-10
-5
0
5
10 neutron proton delta pion
-15 -10 -5 0 5 10 15-15
-10
-5
0
5
10
15t=30 fm/c
Time evolutions of pion, kaon and sigma in the reaction 197Au+197Au at 1.5A GeV by LQMD
Phys. Rev. C 82 (2010) 057901
12
Phenomenological anzatz for pion optical potential: PRC 35 (1987) 2107
Evolution of mesons (pions and kaons )is given by
0 2 4 6 80.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
0 2 4 6 8-6
-5
-4
-3
-2
-1
0
1.50
3.00
(m
)p (mc)
Re V
opt (
m)
p (mc)
13
14
J. Xu, C. M. Ko and Y. Oh, PRC 81 (2010) 024910
Influence of pion optical potential on the -/+ yields in the 197Au+197Au reaction
15
Probing symmetry energy by heavy-ion collisions in the
region of 1 A GeV
16
17
-/+ as a probe of the symmetry energy at supra-saturation densities(Z.-Q. Feng, G.-M. Jin, Phys. Lett. B 683 (2010) 140)
18
19
LQMD: Phys. Lett. B 683 (2010) 140
IBUU04: PRL102(2009)062502
RBUU: PRL97 (2006) 202301; NPA832 (2010) 88
20
Model of Di Toro group (RBUU) PRL97(2006)202301
stifferEsym(20)
IBUU04: PRL102(2009)062502
21
132Sn+124Sn
22
Comparison of calculated direct flow and the FOPI dataarXiv:1006.2459, Phys. Rev. C 82, 044615 (2010)
23
24
Anistropies of - production in 197Au+197Au at Elab=1.5 A GeV
25
Summary
Dynamics of meson productions (pions, kaons) in
the 1A GeV region is described in LQMD model. Pion
flows and in-medium effects are discussed.
Nuclear symmetry energy at supra-saturation
densities is investigated by LQMD model.
Preliminary results support a hard symmetry energy
at high densities close to experimental data.
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