Institute for Advanced Study/Princeton University Early Universe/Cosmology Lunch Discussion

Weak lensing is a powerful tool to extract information from large-scale structures to study the nature of dark matter and dark energy. Two-point correlation function (2PCF) of weak lensing is one of the simplest summary statistics but can extract all the information only if the density fluctuation is Gaussian as in the early universe. The field in the late-time universe is however non-Gaussian due to the nonlinear evolution and additional/independent information is expected to be obtained by analyzing the weak-lensing higher-order statistics. In this talk, I present our recent work on the weak lensing three-point correlation function (3PCF). Compared to the case of 2PCF, the numerical cost is the most challenging part of every step of the 3PCF analysis, which prevented the 3PCF analysis in the past/ongoing surveys. We developed a new method to solve this numerical difficulty based on the multipole expansion of 3PCF, which can calculate the 3PCF 2 orders of magnitude faster.