Effective field theory of coupled dark energy and dark matter
Issued Date
2026-01-01
Resource Type
ISSN
24700010
eISSN
24700029
Scopus ID
2-s2.0-105038121755
Journal Title
Physical Review D
Volume
113
Issue
4
Rights Holder(s)
SCOPUS
Bibliographic Citation
Physical Review D Vol.113 No.4 (2026)
Suggested Citation
Aoki K., Jiménez J.B., Pookkillath M.C., Tsujikawa S. Effective field theory of coupled dark energy and dark matter. Physical Review D Vol.113 No.4 (2026). doi:10.1103/5WSB-1VK6 Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/116770
Title
Effective field theory of coupled dark energy and dark matter
Author(s)
Corresponding Author(s)
Other Contributor(s)
Abstract
We formulate an effective field theory (EFT) of coupled dark energy (DE) and dark matter (DM) interacting through energy and momentum transfers. In the DE sector, we exploit the EFT of vector-tensor theories with the presence of a preferred time direction on the cosmological background. This prescription allows one to accommodate shift-symmetric and nonshift-symmetric scalar-tensor theories by taking a particular weak coupling limit, with and without consistency conditions respectively. We deal with the DM sector as a nonrelativistic perfect fluid, which can be described by a system of three scalar fields. By choosing a unitary gauge in which the perturbations in the DE and DM sectors are eaten by the metric, we incorporate the leading-order operators that characterize the energy and momentum transfers besides those present in the conventional EFT of vector-tensor and scalar-tensor theories and the nonrelativistic perfect fluid. We express the second-order action of scalar perturbations in real space in terms of time- and scale-dependent dimensionless EFT parameters and derive the linear perturbation equations of motion by taking into account additional matter (baryons, radiation). In the small-scale limit, we obtain conditions for the absence of both ghosts and Laplacian instabilities and discuss how they are affected by the DE-DM interactions. We also compute the effective DM gravitational coupling G<inf>eff</inf> by using a quasistatic approximation for perturbations deep inside the DE sound horizon and show that the existence of momentum and energy transfers allow a possibility to realize G<inf>eff</inf> smaller than in the uncoupled case at low redshift.