激光与脉冲星等离子体中一阶QED过程的蒙特卡罗采样
Monte Carlo sampling of first-order QED processes in laser and pulsar plasmas
- University of Helsinki（赫尔辛基大学）
机构由 AI 辅助整理，请以论文原文为准。
中文总结 AI 辅助
本文提出用Padé近似替代查表与数值求逆，对同步辐射和非线性Breit-Wheeler过程进行蒙特卡罗采样，以闭合形式给出量子参数，精度在1%内，可直接用于辐射粒子云胞内代码。
中文摘要 AI 辅助
强场量子电动力学过程的蒙特卡罗采样支撑着高强度激光实验和天体物理致密天体磁层的模拟。对一个事件进行采样需要该过程的总速率以及决定产生粒子之间能量如何分配的累积概率。模拟通常预先将两者制成表格，并通过数值方法对制表概率进行求逆。在此，我们用同步辐射和非线性Breit-Wheeler过程的基本函数近似替代这一流程。对于每个过程，我们使用选定的Padé近似来近似设定总速率的辅助函数以及累积概率，使得求逆过程简化为四次方程。这以闭合形式给出采样的量子参数——电子χ_e或光子χ_γ。这些近似以及从中采样的粒子谱与精确结果在1%以内一致。该流程无需查找表、无需插值、无需数值求根，可直接插入辐射粒子云胞内代码中。
英文摘要
Monte Carlo sampling of strong-field quantum electrodynamics processes underpins simulations of high-intensity laser experiments and of astrophysical compact-object magnetospheres. Sampling an event requires the total rate of the process together with the cumulative probability that determines how energy is partitioned between the produced particles. Simulations typically tabulate both in advance and invert the tabulated probability numerically. Here we replace this procedure with elementary-function approximations for synchrotron radiation and the nonlinear Breit--Wheeler process. For each process, we approximate the auxiliary function that sets the total rate, as well as the cumulative probability, with Padé approximants chosen so that the inversion reduces to a quartic equation. This yields the sampled quantum parameter---electron $χ_e$ or photon $χ_γ$---in closed form. The approximations and the particle spectra sampled from them agree with the exact results to within $1\%$. The procedure requires no lookup tables, no interpolation, and no numerical root finding, and can be inserted directly into radiative particle-in-cell codes.
