We study two key issues militating against the use of the anisotropic three-point correlation function (3PCF) for cosmological parameter inference: difficulties with its computational estimation and high-dimensionality. We show how high-dimensionality may be reduced significantly by multipole decompositions of all angular dependence. This allows deriving the full expression for the multipole moments of the anisotropic 3PCF and its covariance matrix in a basis where the dimensionality reduces from nine to two at each multipole in the plane-parallel limit. We use 2D FFTLog formalism to show how the multipole moments with double momentum integrals over the product of bispectrum and two highly oscillating spherical Bessel functions and its covariance with double momentum integrals over the product of three galaxy power spectra and a combination of four highly oscillating spherical Bessel functions may be computed optimally.

我们研究了阻碍使用各向异性三点相关函数 (3PCF) 进行宇宙学参数推断的两个关键问题：计算估计的困难和高维。我们展示了如何通过所有角度相关的多极分解来显着降低高维。这允许推导出各向异性 3PCF 的多极矩及其协方差矩阵的完整表达式，其中维数在平面平行极限中的每个多极点处从九减少到二。