Title: Principal Shapes and Squeezed Limits in the Effective Field Theory of Large Scale Structure Show Chinese title

Title: 主形状和大尺度结构有效场论中的压缩极限

Abstract: We apply an orthogonalization procedure on the effective field theory of large scale structure (EFT of LSS) shapes, relevant for the angle-averaged bispectrum and non-Gaussian covariance of the matter power spectrum at one loop. Assuming natural-sized EFT parameters, this identifies a linear combination of EFT shapes - referred to as the principal shape - that gives the dominant contribution for the whole kinematic plane, with subdominant combinations suppressed by a few orders of magnitude. For the covariance, our orthogonal transformation is in excellent agreement with a principal component analysis applied to available data. Additionally we find that, for both observables, the coefficients of the principal shapes are well approximated by the EFT coefficients appearing in the squeezed limit, and are thus measurable from power spectrum response functions. Employing data from N-body simulations for the growth-only response, we measure the single EFT coefficient describing the angle-averaged bispectrum with $\mathcal{O}(10\%)$ precision. These methods of shape orthogonalization and measurement of coefficients from response functions are valuable tools for developing the EFT of LSS framework, and can be applied to more general observables. Show Chinese abstract

Abstract: 我们在大尺度结构的有效场理论（EFT of LSS）形状上应用了一个正交化过程，这些形状与角度平均的三阶谱和物质功率谱的一环非高斯协方差相关。 假设EFT参数为自然大小，这确定了一个EFT形状的线性组合——称为主形状——它在整个运动学平面上给出主要贡献，而次级组合被抑制了几倍的数量级。 对于协方差，我们的正交变换与对现有数据应用的主成分分析非常一致。 此外，我们发现对于这两个观测量，主形状的系数可以很好地由挤压极限中出现的EFT系数近似，并因此可以从功率谱响应函数中测量。 利用仅增长的响应数据来自N体模拟，我们以$\mathcal{O}(10\%)$的精度测量了描述角度平均三阶谱的单一EFT系数。 这些形状正交化和从响应函数中测量系数的方法是发展EFT of LSS框架的有用工具，并可以应用于更一般的观测量。