Emergent structures in open EFTs

Abstract: Open effective field theories (EFTs) provide a systematic framework for describing systems coupled to an environment, where dissipation, noise, and modified conservation laws naturally arise. Working within the Schwinger-Keldysh formalism, we examine open extensions of well-studied theories describing a spontaneous symmetry breaking phase in the higher-form sense: the superfluid, Maxwell theory, and Einstein's gravity. We demonstrate that to leading order breaking advanced symmetries while preserving the physical ones leads to (i) deformed conservation laws that hold at the level of expectation values for global symmetries and (ii) deformed noise constraints in gauge or gravitational theories.