Constraining nuclear symmetry energy from highenergy heavyion collisions

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 l Introduction l Lanzhou Quantum Molecular Dynamics (LQMD) model l Particle production in LQMD model l Probing equation of state (EOS) and symmetry energy by heavy-ion collisions in the region of 1 A Ge. V l Summary 2

Introduction Promising probes of the Esym(ρ) in Nuclear Reactions B. A. Li, L. W. Chen, C. M. Ko, Phys. Rep. 464(2008) 113 -281 3

L. W. Chen, C. M. Ko, and B. A. Li PRC 72, 064309 (2005); PRC 76, 054316 (2007) Z. H. Li et al. , PRC 74, 047304(2006) Dieperink et al. , PRC 68, 064307(2003) 4

Different symmetry energies used in transport models IBUU 04 LQMD 5

Lanzhou-Quantum-Molecular- Dynamics (LQMD) project ü Dynamics of low-energy heavy-ion collisions (dynamical interaction potential, barrier distribution, neck dynamics, fusion/caption excitation functions etc) ü Isospin physics at intermediate energies (constraining symmetry energy at sub or supra saturation densities in HICs) Ø 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 , ) Ø Dilepton production (e+e-) at near threshold energies in heavy-ion collisions and proton induced reactions. 6

Lanzhou Quantum Molecular Dynamics (LQMD) Refs: NPA 750(2005)232, NPA 802(2008)91, PRC 80(2009)037601, PLB 683(2010)140, PRC 82(2010)044615, 82(2010)057901 Evolution of baryons (nucleons and resonances ) 7

Symmetry energy per nucleon in the LQMD model is derived from the Skyrme energy-density functional More clearly compared with other transport models, e. g. , IBUU 04, RBUU, SMF etc with Cpot=38 Me. V, a=37. 7 Me. V, b=-18. 7 Me. V which gives the Esym=31. 5 Me. V at = 0=0. 165 8

Reaction channels for pion production: (1232), N*(1440), N*(1535) Channels of kaon production near threshold Energies: B(N, ), K(K 0, K+), Kb(Kb 0, K-), Y( , -, 0, +) BB BYK, BB BBKKb, B YK, B NKKb, Y NKb, NKb Y , YN Kb. NN 9

NN elastic and inelastic cross sections (Z. -Q. Feng and G. -M. Jin, Chin. Phys. Lett. 26 (2009) 062501) 10

Evolution of nucleons, resonances and pions calculated by LQMD 197 Au+197 Au, 1 A Ge. V 11

Time evolutions of pion, kaon and sigma in the reaction 197 Au+197 Au at 1. 5 A Ge. V by LQMD Phys. Rev. C 82 (2010) 057901 12

Evolution of mesons (pions and kaons )is given by Phenomenological anzatz for pion optical potential: PRC 35 (1987) 2107 13

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Influence of pion optical potential on the -/ + yields in the 197 Au+197 Au reaction J. Xu, C. M. Ko and Y. Oh, PRC 81 (2010) 024910 15

Probing symmetry energy by heavy-ion collisions in the region of 1 A Ge. V 16

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-/ + as a probe of the symmetry energy at supra-saturation densities (Z. -Q. Feng, G. -M. Jin, Phys. Lett. B 683 (2010) 140) 18

LQMD: Phys. Lett. B 683 (2010) 140 IBUU 04: PRL 102(2009)062502 19

RBUU: PRL 97 (2006) 202301; NPA 832 (2010) 88 20

Model of Di Toro group (RBUU) PRL 97(2006)202301 IBUU 04: PRL 102(2009)062502 stiffer Esym(2 0) 21

132 Sn+124 Sn 22

Comparison of calculated direct flow and the FOPI data ar. Xiv: 1006. 2459, Phys. Rev. C 82, 044615 (2010) 23

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Anistropies of - production in 197 Au+197 Au at Elab=1. 5 A Ge. V 25

Summary ü Dynamics of meson productions (pions, kaons) in the 1 A Ge. V region is described in LQMD model. Pion flows and in-medium effects are discussed. ü 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. 26