Gravitational open effective field theory of inflation

TL;DR

The paper addresses the challenge of embedding dissipative, open-system physics into a gravitationally consistent EFT of inflation. It shows that most open terms in the Schwinger–Keldysh framework would overconstrain the dynamics unless a careful deformation of the diffeomorphism structure is imposed. The authors construct a minimal open-extension using a trace-adjusted extrinsic-curvature term that yields a deformed identity, ensuring three propagating degrees of freedom and a Langevin-type equation with dissipation and noise. They derive the scalar EOM and compute the scalar power spectrum, including noise contributions, recovering the standard closed EFT in the appropriate limit. This work provides a systematic foundation for dissipative inflation in a gravitational setting and outlines paths to classify open operators and explore observable signatures such as non-Gaussianities in open-SK inflation.

Abstract

We construct a gravitational open extension of the effective field theory of inflation in the Schwinger-Keldysh framework. While physical symmetries allow many open operators in the Schwinger-Keldysh action, most of them overconstrain the equations of motion, yielding inconsistent dynamics. We identify the minimal open operators compatible with propagating scalar and tensor modes and build the gravitational action, recovering dissipative models of inflation.