不损失流交叉的大尺度结构摄动理论
Large-scale structure perturbation theory without losing stream crossing
摘要：
我们提出了一种方法来微扰计算宇宙中的大规模集群，包括从一开始的流交叉（多个速度的质量元素在一个单一的位置），这是在传统的计算中丢失。从位移上的泛函积分开始，微扰级数展开与（截断的）泽尔多维奇演化有偏差，即使对于跨流位移也可以精确计算。我们评估的位移和密度功率谱数值在1D的单回路公式，发现显着的改善与N体模拟相比，泽尔多维奇功率谱（这是准确的在1D流交叉）。除了1D之外，我们的方法可以代表对以前的扩展的改进，即使除了包含流交叉，但我们还没有在数值上对此进行研究。在这个过程中，我们展示了如何实现有效的理论般的小尺度波动的监管没有自由参数。
英文摘要：
We suggest an approach to perturbative calculations of large-scale clustering in the Universe that includes from the start the stream crossing (multiple velocities for mass elements at a single position) that is lost in traditional calculations. Starting from a functional integral over displacement, the perturbative series expansion is in deviations from (truncated) Zel'dovich evolution, with terms that can be computed exactly even for stream-crossed displacements. We evaluate the one-loop formulas for displacement and density power spectra numerically in 1D, finding dramatic improvement in agreement with N-body simulations compared to the Zel'dovich power spectrum (which is exact in 1D up to stream crossing). Beyond 1D, our approach could represent an improvement over previous expansions even aside from the inclusion of stream crossing, but we have not investigated this numerically. In the process we show how to achieve effective-theory-like regulation of small-scale fluctuations without free parameters.
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