Playing LEGOs with Feynman diagrams on FLRW spacetimes

Computing correlators is hard. Computing correlators on a curved background is harder. Going to higher point function gets even harder as the number of integrals increase. However, using recursion relations one can play LEGOs with the Feynman diagrams. The higher point diagrams can be written as gluing of lower point ones. In this talk, I will introduce how to play this game for diagrams on an FLRW background. In particular, I will focus on examples of different types of interactions, like conformal scalar on general FLRW, EFT of inflation, and massive scalar, and compute some table diagrams and loop integrands. At last, I will present a way to "massify" any internal line with a trick and write its correlator in terms of an infinite series. This would allow one to extend these tricks to different topologies of diagrams at higher points even with massive exchange.