Title: Effect of lensing non-Gaussianity on the CMB power spectra Show Chinese title

Title: 透镜效应非高斯性对CMB功率谱的影响

Abstract: Observed CMB anisotropies are lensed, and the lensed power spectra can be calculated accurately assuming the lensing deflections are Gaussian. However, the lensing deflections are actually slightly non-Gaussian due to both non-linear large-scale structure growth and post-Born corrections. We calculate the leading correction to the lensed CMB power spectra from the non-Gaussianity, which is determined by the lensing bispectrum. The lowest-order result gives $\sim 0.3\%$ corrections to the BB and EE polarization spectra on small-scales, however we show that the effect on EE is reduced by about a factor of two by higher-order Gaussian lensing smoothing, rendering the total effect safely negligible for the foreseeable future. We give a simple analytic model for the signal expected from skewness of the large-scale lensing field; the effect is similar to a net demagnification and hence a small change in acoustic scale (and therefore out of phase with the dominant lensing smoothing that predominantly affects the peaks and troughs of the power spectrum). Show Chinese abstract

Abstract: 观测到的CMB各向异性是透镜效应造成的，假设透镜偏移量是高斯分布的，可以准确计算透镜后的功率谱。 然而，由于大尺度结构的非线性增长和后-Born修正，透镜偏移量实际上是略微非高斯的。 我们计算了由非高斯性引起的透镜CMB功率谱的主要修正，该修正由透镜三阶矩决定。 最低阶结果给出了在小尺度上对BB和EE极化谱的$\sim 0.3\%$修正，然而我们表明，通过更高阶的高斯透镜平滑，EE上的影响大约减少了一半，因此对于可预见的未来，总的影响可以安全地忽略。 我们给出了一个简单的解析模型，用于预测大尺度透镜场偏度带来的信号；该效应类似于净去放大，因此导致声学尺度的小幅变化（因此与主要的透镜平滑效应相位相反，该效应主要影响功率谱的峰值和谷值）。