中高能重离子碰撞中奇异粒子产生和超核形成机制  

Strange particle production and hypernucleus formation in medium and high energy heavy-ion collisions

作　　者：冯兆庆[1] Zhaoqing Feng(Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, Chin)

机构地区：[1]中国科学院近代物理研究所,兰州730000

出　　处：《科学通报》2018年第8期735-744,共10页Chinese Science Bulletin

基　　金：国家自然科学基金(11722546;11675226);中国科学院前沿科学重点项目(QYZDJ-SSW-SLH041)资助

摘　　要：中高能重离子碰撞可以形成大于饱和密度的核物质状态.高密核物质中奇异粒子成分影响核物质状态方程.重离子碰撞是产生丰中子超核的唯一途径.本文评述了中高能重离子碰撞中奇异粒子研究最新进展,讨论了在我国强流重离子加速器(HIAF)上开展核物质状态方程和丰中子超核研究的可行性.基于兰州量子分子动力学模型,以反应系统^(58)Ni+^(58)Ni和^(197)Au+^(197)Au为例,分析了阈能附近奇异粒子产生动力学和高密核物质状态方程;系统研究了Λ超核形成动力学机制并给出了超核的质量、电荷、动能分布和动能谱;讨论了核物质状态方程和碰撞中心度对奇异粒子产生和超核形成的影响.研究结果表明,K介子在高动能部分产额可以提取高重子密度下核物质状态方程;Λ超子与核子相互作用势会影响超核的形成,如吸引的相互作用势有利于超核的形成;重离子碰撞有利于形成轻质量区超核并且碰撞中心度对超核的形成有重要影响.The nuclear matter at supra-saturation densities might be created in medium and high energy heavy-ion collisions. The strangeness ingredient in dense nuclear matter impacts the equation of state and maybe exists in the neutron stars. On the other hand, heavy-ion collisions provide a unique way for producing the neutron-rich hypernuclides. In this article, the new progress on strangeness physics in heavy-ion collisions is reviewed. Possible experiments at the high-intensity heavy-ion accelerator facility （HIAF） are to be discussed, in particular on the topics of the high-density nuclear equation of state and hypernuclide in the neutron-rich domain. Within the framework of the Lanzhou quantum molecular dynamics （LQMD） model, the strangeness production and high-density nuclear equation of state in heavy-ion collisions near threshold energies has been investigated, i.e., for the reactions of 58Ni＋58Ni and 197Au＋197Au. The formation mechanism of A-hyperfragments in heavy-ion collisions is to be investigated. A coalescence approach is developed for constructing the primary fragments in phase space. The secondary decay process of the fragments is described by the well-known statistical code. The impacts of nuclear equation of state on the hyperfragment formation are discussed. The mass, charge and kinetic energy spectra of hypernuclides produced in heavy-ion collisions are thoroughly analyzed. It is found that the kaon yields in the high kinetic energy domain are useful for extracting the high-density nuclear equation of state. The K~ yields are strongly suppressed with a hard equation of state. However, the hyperon production is weakly influenced by the incompressibility of nuclear matter. The A-nucleon potential impacts the hypernuclide formation, i.e., the attractive potential enhancing the hypernuclide yields. The heavy-ion collisions are available to produce the light mass neutron-rich hypernuclides and the mid-central collisions are favorable for the medium mass hypernuclide formation. Free hyperons ar

关 键 词：重离子碰撞 奇异粒子产生 状态方程 超核形成 兰州量子分子动力学模型 

分 类 号：O571.6[理学—粒子物理与原子核物理]