Multifield theories invariant under transverse diffeomorphisms: The mixed regime case
Abstract
We study theories breaking diffeomorphism (Diff) invariance down to the subgroup of transverse diffeomorphisms (TDiff), consisting of multiple scalar fields in a cosmological background. In particular, we focus on models involving a field dominated by its kinetic term and a field dominated by its potential, coupled to gravity through power-law functions of the metric determinant. The Diff symmetry breaking results in the individual energy-momentum tensors not being conserved, although the total conservation-law is satisfied. Consequently, an energy exchange takes place between the fields, acting as an effective interaction between them. With this in mind, we consider the covariantized approach to describe the theory in a Diff invariant way but with an additional field, and discuss the phenomenological consequences of these models when it comes to the study of the dark sector.
Cite
@article{arxiv.2507.16616,
title = {Multifield theories invariant under transverse diffeomorphisms: The mixed regime case},
author = {Antonio L. Maroto and Prado Martín-Moruno and Diego Tessainer},
journal= {arXiv preprint arXiv:2507.16616},
year = {2026}
}
Comments
14 pages, 7 figures V2: Brief comment regarding the degrees of freedom in the covariantized approach added in the beginning of section III. V2: Brief comment regarding the Equivalence principle introduced before section III-A. V2: End of the introduction slightly clarified. V3: Title updated to match the published journal version