重离子碰撞中阈能附近超子产生机制  

Hyperon Dynamics and Production in Heavy-ion Collisions Near Threshold Energy

作　　者：张定昌 冯兆庆 ZHANG Dingchang;FENG Zhaoqing(School of Physics and Optoelectronic Technology,South China University of Technology,Guangzhou 510641,China)

机构地区：[1]华南理工大学物理与光电学院,广州510641

出　　处：《原子核物理评论》2022年第1期1-15,共15页Nuclear Physics Review

基　　金：国家自然科学基金资助项目(12175072,11722546);华南理工大学双一流建设经费(20210115)。

摘　　要：在量子分子动力学输运模型LQMD(Lanzhou quantum molecular dynamics transport model)框架下,研究了不同重离子反应系统中同位旋和核介质效应对超子产生以及动能谱的影响。基于手征有效场理论,引入了动量和密度相关的排斥超子-核子光学势,并且考虑了该势对超子产生截面阈能的修正。结果表明,Σ超子的产生在中心快度区域和动能谱中被抑制,其集体出射的行为也受到影响,超子在反应平面内将更倾向于沿束流方向运动,在出平面内倾向于沿垂直反应平面方向运动。最后,分析了高能区域Σ^(-)/Σ^(+)比值对高密核物质对称能软硬的依赖,发现排斥的超子-核子光学势增大了对称能较硬情况下Σ^(-)/Σ^(+)比值,同时发现核物质不可压缩系数会明显影响超子的产生。Within the framework of Lanzhou quantum molecular dynamics(LQMD)transport model,the isospin and in-medium effects on the hyperon production and kinetic energy spectra in the reaction of different heavy-ion reaction are investigated thoroughly.A repulsive hyperon-nucleon potential which is related to the hyperon momentum and baryon density from the chiral effective field theory is implemented into the model.The correction on threshold energy of the elementary hyperon cross section is taken into account.It is found that theΣyields are suppressed in the domain of midrapidity and domain of kinetic energy spectra with the potential.The emission behavior of the hyperons is also affected by the repulsive hyperon-nucleon potential.The hyperons tend to move along the direction of the beam and along the direction perpendicular to the reaction plane.Finally,we found thatΣ^(-)/Σ^(+)yield ratio depends on the stiffness of nuclear symmetry energy in the high-energy region.TheΣ^(-)/Σ^(+)yield ratio with a hard symmetry energy is increased by the repulsive hyperon-nucleon potential.And it is found that the compressibility of nuclear matter will affect the hyperon production obviously.

关 键 词：LQMD模型 超子产生 介质效应 集体流 对称能 

分 类 号：O571.53[理学—粒子物理与原子核物理]