Speaker
Description
Effective field theories (EFTs) provide a powerful framework to parametrise unknown aspects of possible ultraviolet (UV) physics. However, compared to traditional EFTs for scattering amplitudes in flat space, there are at least three distinct sources of subtlety in EFTs for cosmological correlators in de Sitter space, which include (1) the expansion of the spacetime background itself, (2) the breakdown of unitarity and the necessary inclusion of dissipation effect and stochastic noise, and (3) the enhanced role of infrared (IR) divergences and the need to resum secular growth. In this talk, I will explain how to construct the appropriate (open) EFTs for general cosmological correlators. In particular, I will consider equal-time correlation functions of massless inflaton with exchanges of massive spectator fields via both IR-finite and IR-divergent couplings. With the knowledge of analytic computations in the UV theories, we can determine the (dominant) EFT operators in the IR theories and the corresponding Wilson coefficients by the standard matching process.
