KN势对重离子碰撞中K介子产生的影响

The influence of KN potential on the production of kaon mesons in heavy-ion collisions at intermediate energies

重离子碰撞中产生的K介子是核反应中形成的高密核物质的一个有效探针,结合输运模型模拟可以提取出高密核物质状态方程的信息.在最近更新的极端相对论量子分子动力学(UrQMD)模型基础上,引入了K介子与核子相互作用势(KN势),以中能区(入射能量为0.6–2.0GeV/nucleon)Au+Au碰撞为例,研究了KN势对K介子产额和直接流、椭圆流的影响.当考虑KN势后,能够更好地再现K介子集体流的实验数据.还发现K^0/K^+产额比依赖于对称能的"软硬".发现"软"的对称能给出的K^0/K^+产额比高于"硬"的对称能给出的结果;入射能量越低,K^0/K^+产额比对对称能的敏感性就越强.入射能量为0.8GeV/nucleon时K^0/K^+产额比对对称能的敏感性要高于π-/π+产额比.

The kaon meson produced in heavy ion collisions can be taken as a useful probe for investigating the properties of dense nuclear matter. With the help of transport model simulations, it can be used to extract the information of the equation of state of nuclear matter. Within the newly updated version of the ultrarelativistic quantum molecular dynamics （UrQMD） model, the kaon-nucleon （KN） potential is further taken into account and its influence on both the yield and the directed and elliptic flows of kaon mesons produced in Au＋Au collisions at intermediate energies （Elab=0.6-2.0 GeV/nucleon） is investigated. It is found that the experimental data of flows can be better described with the consideration of the KN potential, and it is further found that the K0/K＋ yield ratio is affected by the density dependence of the nuclear symmetry energy. The K0/K＋ ratio calculated with a soft symmetry energy is larger than that with a stiff one, and the sensitivity to the density dependence of the nuclear symmetry energy at lower beam energy becomes larger. At the low energy such as 0.8 GeV/nucleon, the K0/K＋ ratio is more sensitive to the stiffness of nuclear symmetry energy than the π-/π＋ ratio is.