本项目将在包含核子、Delta共振态及pion介子等强子物质的自洽RBUU输运理论及微观非平衡动力学输运模型UrQMD的基础上深入研究影响探测高密区对称能密度依赖敏感观测量的若干理论和模型依赖问题。理论方面，在同位旋不对称核系统中这些强子的平均场修正与两体碰撞(包括存在的质量劈裂与动量依赖等)是研究的重点。在模型计算过程中，反应系统的初始化稳定性、与末态碎片同位旋相关的重构等都需要更严谨地处理。在此基础上更新的UrQMD模型将用于针对性地研究包括我国兰州CSR在内的国内外几个主流国家实验室即将和正在开展的对高密区对称能密度依赖的实验观测量,如轻碎片的集体流差或比、pion-/pion+产额比。通过对实验条件的充分考虑和把多个观测量的模型计算与实验结果进行比较，为最终确定高密区对称能的密度依赖形式提供可能。

In this project, several theoretical and model-dependent issues , which affect probing the density dependence of the symmetry energy at high densities, will be intensively studied based on the self-consistent relativistic Boltzmann-Uehling-Uhlenbeck (RBUU) transport theory, which includes interactions of nucleons, Delta resonances and pion mesons, and the microscopic non-equilibrium dynamic transport model, the Ultra-relativistic Quantum Molecular Dynamics (UrQMD).On the theoretical side, the mean-field modification and the binary collision (including the mass-splitting and momentum dependent effects) of these hadrons in the isospin asymmetric nuclear system will be focused. During the process of the model calculation, the stablization of initialization of the reaction system and the isospin-dependent recognition of fragments at the late stage of reactions should be treated more carefully. Based on such an updated UrQMD model, experimental observables which are sensitive to the density dependence of the symmetry energy, measured or to be measured by several main national laboratories of the world (including our CSR at Lanzhou), will be specifically studied. With a careful consideration of experimental conditions and by the comparison of model calculations with experimental data of several observables such as the collective flow difference or ratio of light clusters, and the yield ratio of pion- and pion+ mesons, it is hoped to pin down the behavior of the symmetry energy at high densities at last.