Within the transport model evaluation project (TMEP) of simulations for heavy-ion collisions, the mean-field response is examined here. Specifically, zero-sound propagation is considered for neutron-proton symmetric matter enclosed in a periodic box, at zero temperature and around normal density. The results of several transport codes belonging to two families (BUU-like and QMD-like) are compared among each other and to exact calculations. For BUU-like codes, employing the test particle method, the results depend on the combination of the number of test particles and the spread of the profile functions that weight integration over space. These parameters can be properly adapted to give a good reproduction of the analytical zero-sound features. QMD-like codes, using molecular dynamics methods, are characterized by large damping effects, attributable to the fluctuations inherent in their phase-space representation. Moreover, for a given nuclear effective interaction, they generally lead to slower density oscillations, as compared to BUU-like codes. The latter problem is mitigated in the more recent lattice formulation of some of the QMD codes. The significance of these results for the description of real heavy-ion collisions is discussed.

中文翻译：

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重离子传输模拟的比较：盒子中的平均场动力学

在模拟重离子碰撞的输运模型评估项目 (TMEP) 中，这里检查了平均场响应。具体来说，零声传播被认为是封闭在周期盒子中的中子 - 质子对称物质，在零温度和正常密度附近。属于两个家族（BUU 类和 QMD 类）的几个传输代码的结果相互比较并进行精确计算。对于类似BUU的代码，采用测试粒子方法，结果取决于测试粒子的数量和对空间加权积分的轮廓函数的分布的组合。可以适当地调整这些参数以很好地再现分析零声特征。类似 QMD 的代码，使用分子动力学方法，其特点是阻尼效应大，归因于其相空间表示中固有的波动。此外，对于给定的核有效相互作用，与类似 BUU 的代码相比，它们通常会导致较慢的密度振荡。后一个问题在一些 QMD 代码的更新点阵公式中得到缓解。讨论了这些结果对于描述真实重离子碰撞的意义。