EFT of interacting dark energy and dark matter

by Masroor Pookkillath (Sogang U.)

Thursday 13 Nov 2025, 14:00 → 16:00 Asia/Seoul

B447-1 (IBS CTPU-CGA)

I present an effective field theory (EFT) framework for coupled dark energy (DE) and dark matter (DM) with explicit energy and momentum exchange. The DE sector is formulated within the EFT of vector–tensor theories, where the cosmological background selects a preferred time direction. This setting unifies both shift-symmetric and non-shift-symmetric scalar–tensor theories through appropriate weak-coupling limits, with or without additional consistency conditions. The DM sector is modeled as a non-relativistic perfect fluid, described by three scalar fields. Working in unitary gauge, where DE and DM perturbations are absorbed into the metric, we systematically construct the leading-order operators that govern energy and momentum transfers. These operators extend the standard EFT ingredients of vector–tensor and scalar–tensor theories as well as non-relativistic fluids, providing a general and flexible formalism to capture dark-sector interactions. The presentation is based on our recent development in arXiv:2504.17293 (under review).