Schwinger-Keldysh effective actions for Goldstone bosons

Expectation values in quantum field theory are calculated using the Schwinger-Keldysh (or in-in) formalism. In recent years, significant progress has been made towards recasting this formalism in a modern effective field theory language. In this talk, I will introduce a systematic procedure to formulate in-in effective actions for systems in which some symmetries are spontaneously broken. The results I will discuss have broad applicability, and are relevant for a variety of areas ranging from condensed matter to cosmology.