关键词: 
兰州量子分子动力学模型 /
K- 核子相互作用势 /
对称能 /
K0/K+

摘要: 基于兰州量子分子动力学(LQMD) 模型研究了阈能附近K介子(K0 和K+) 产生动力学机制。LQMD模型能够较好地描述中能重离子碰撞中K介子产额分布。通过拟合K介子动能谱分布，计算中采用了排斥的K-核子相互作用势。该光学势增强了高动量K介子产生，而降低了K介子总产额。结合实验数据比较，在高密区域给出了较软的对称核物质状态方程。对称能的软硬对K0/K+ 比值起着重要作用，特别是在阈下区域。而K介子光学势对K0/K+ 比值激发函数影响不明显。Dynamics of kaons (K0 and K+) produced in nuclear reactions near threshold energies has been investigated within the Lanzhou quantum molecular dynamics (LQMD) transport model.The production yields are consistent with the available experimental data. A repulsive kaon-nucleon potential is implemented in the model through fitting the kinetic energy spectra of inclusive cross sections in heavy-ion collisions, which enhances the energetic kaon emission squeezed out in the reaction zone and reduces the total kaon yields. The comparison to the available data supports a soft equation of state in the density region of 2 ~3ρ₀ for isospin symmetric nuclear matter. It is found that the stiffness of nuclear symmetry energy plays a significant role on the isospin ratio with decreasing the incident energy, in particularly in the domain of subthreshold energies.