Gravitational EFT for dissipative open systems

by Mr Kanji Nishii (Kobe University)

Thursday 27 Feb 2025, 16:00 → 17:30 Asia/Seoul

Title: Gravitational EFT for dissipative open systems

Speaker: Kanji Nishii (Kobe U.)

Abstract: We elaborate on the effective field theory (EFT) construction for dissipative open systems coupled to dynamical gravity, in light of recent developments on the EFT of dissipative hydrodynamics (HydroEFT). Our construction is based on the Schwinger-Keldysh formalism and its symmetries, as well as microscopic unitarity. A key aspect of dynamical gravity is that it couples universally to all degrees of freedom, meaning that the EFT must account for the energy-momentum tensor of the environment to which energy escapes from the dissipative system of interest. We incorporate this effect by modeling the environment using HydroEFT, assuming the validity of the derivative expansion in the environment sector.
For illustration, we apply our EFT framework to a dissipative scalar field coupled to dynamical gravity, which can be used, for example, in the context of dissipative inflation. In particular, we quantify the impact of fluctuations in the environment sector on the scalar field dynamics. We also apply the same framework to dissipative gravity, discussing dissipative gravitational waves and the generalized second law of black hole thermodynamics.