Gravitational open effective field theory of inflation

A bstract 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 a minimal open operator compatible with propagating scalar and tensor modes and build a local gravitational action, recovering known dissipative models of inflation.