The study of scalar field theory in de Sitter spacetime is of great importance in many facets of inflationary cosmology; however current perturbative techniques in QFT contain IR divergences that seriously limit its computational power. Instead, we turn to effective theories. One such theory is the stochastic approach, where one utilises the inflationary expansion to write the scalar field equations in a stochastic framework. In this talk, I will introduce a second-order stochastic effective theory of spectator scalar fields in de Sitter in the light field limit, extending the stochastic approach beyond the massless limit and demonstrating how it can be used to compute long-distance correlation functions non-perturbatively.
Zoom link: https://uu-se.zoom.us/j/69088161836?pwd=Z01mK1RJdTlZUTJFeFVqbE83WXBQUT09