标题： 重离子碰撞中低SIS能量下的非平衡动力学 显示英文标题

标题： Non-equilibrium dynamics in heavy ion collisions at low SIS energies

摘要： 超相对论量子分子动力学（UrQMD）模型是一种微观输运模型，用于研究在INDRA和低能FOPI实验覆盖的入射能量下，金-金碰撞中的定向和椭圆集体流以及核停止效应。 显然，这些可观测量对状态方程（EoS）中的势能项（包括标量同位旋和矢量同位旋部分以及动量相关项）和碰撞项（包括泡利阻塞和介质修改的核子-核子弹性截面（NNECS））都敏感。 发现平均场势和密度依赖的NNECS的动量修正对重离子碰撞的集体性非常敏感。 在INDRA能量（$\le 150$~MeV/核子）下，使用具有动量相关的软状态方程以及动量修正的密度依赖的NNECS的动态输运模型能够很好地描述在中间快速度下由氢同位素（$Z=1$）表现出的定向流。 显示英文摘要

摘要： The Ultrarelativistic Quantum Molecular Dynamics (UrQMD) model, a microscopic transport model, is used to study the directed and elliptic collective flows and the nuclear stopping in Au+Au collisions at incident energies covered by INDRA and lower-energy FOPI experiments. It is seen clearly that these observables are sensitive to both, the potential terms (including iso-scalar and iso-vector parts as well as the momentum dependent term) in the equation of state (EoS) and the collision term (including the Pauli-blocking and the medium-modified nucleon-nucleon elastic cross section (NNECS)). The momentum modifications of both, the mean-field potentials and the density dependent NNECS, are found to be sensitive to the collectivity of heavy-ion collisions. At INDRA energies ($\le 150$~MeV/nucleon), the dynamic transport with a soft EoS with momentum dependence and with the momentum-modified density-dependent NNECS describes the directed flow exhibited by hydrogen isotopes ($Z=1$) emitted at mid-rapidity fairly well.