重离子碰撞量子输运的半经典描述

Semiclassical descriptions for quantum transport of heavy-ion collisions

本文介绍了用于模拟中能重离子碰撞的输运模型,包括玻尔兹曼输运模型和量子分子动力学输运模型.前者数值求解单体相空间分布函数基于玻尔兹曼输运方程的演化,后者模拟多体哈密顿量作用下高斯波包描述的核子演化,两类模型对输运模拟的初始化、平均场、核子-核子散射均有不同处理.将输运模拟结果与中能重离子碰撞实验数据相比较,是获取核力及核物质状态方程的重要手段之一.为了减小由于模型依赖性所造成的理论误差,国际输运领域专家进行了不懈的努力,十多年来比较评估了约二十个输运模型对重离子碰撞体系和周期性边界的箱体体系中的模拟计算结果,包括核子之间的碰撞率与泡利阻塞、核子的集体流以及介子的产生等,取得了阶段性的成果.

This article gives a brief review on transport models for the simulations of intermediate-energy heavy-ion collisions,including the Boltzmann transport models and the quantum molecular dynamics transport models.The former solve numerically the evolution of the one-body phase-space distribution function based on the Boltzmann equation,while the latter simulate the evolution of nucleons described by Gaussian wave-packets under the many-body Hamiltonian.Different treatments for the initialization,the mean-field potential,as well as the nucleon-nucleon scatterings are applied in the two type transport models.Comparing transport simulation results with the experimental data of intermediateenergy heavy-ion collisions is one of the main means to extract the information of the nuclear force and the nuclear equation of state.In order to reduce the theoretical uncertainties of transport simulations,continuous efforts have been made by experts of transport models all over the world.In the past decade,simulation results from about twenty transport models are compared and evaluated in systems of heavy-ion collisions and the box with the periodic boundary condition,mainly concentrating on nucleon-nucleon collisions and the Pauli blocking,the nucleon collective flow,and the meson production,etc.