Cosmological stasis and the coupled dark sector of the Dark Dimension
Abstract
We study cosmological stasis in coupled dark matter and dark energy models in which a scalar field drives the dark energy and sets the dark matter mass, with the Dark Dimension as the motivating realization. Treating dark matter, dark energy, baryons, and radiation as an autonomous dynamical system, we show that exact stasis requires exponential slopes along the trajectory, and that running slopes give exact stasis or a drifting quasi-stasis depending on whether the running is integrable. The constant abundance solutions are the stationary solutions of coupled quintessence, which we read as stasis epochs with computable lifetimes and exits. Anchoring the cosmology to the measured abundances at matter-radiation equality and today, we show that the stasis region for this model cannot accelerate for any initial conditions, and that the total equation of state is never phantom although the effective dark energy of a ΛCDM fit can appear so. For the Dark Dimension, capture into stasis in the future is excluded for geometric sources of the potential once dark fifth-force bounds are imposed, and dark matter production from the Standard Model brane supports a further stasis which the standard scenario does not reach. The stasis solutions provide analytic exclusions of the parameter space which do not depend on initial conditions.
Related
- Cosmological axion-photon interactions with a nonminimal dark gauge sector
- Cosmological tests of chameleon dark energy with dark sector coupling
- Four-Sector Cosmology (FSC): A Complex Dark Energy Field, Spontaneous Symmetry Breaking, and the Origin of the Cosmological Constant from Observed Matter Asymmetry δ = 0.2%
- Studies on the dark sector interaction from joint analysis of cosmological probes
- The alternative scalar field dark sector of the Universe: Cosmological inflation, quintessence and ekpyrotic model in the framework of scalar-tensor cosmology
BibTeX
@misc{stewart2026cosmological,
title = {{Cosmological stasis and the coupled dark sector of the Dark Dimension}},
author = {Alexander Stewart},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2609.25230},
eprint = {2609.25230},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.25230},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Cosmological stasis and the coupled dark sector of the Dark Dimension
AU - Alexander Stewart
PY - 2026
DA - 2026/10/04
PB - arXiv
DO - 10.48550/arxiv.2609.25230
UR - https://arxiv.org/abs/2609.25230
AB - We study cosmological stasis in coupled dark matter and dark energy models in which a scalar field drives the dark energy and sets the dark matter mass, with the Dark Dimension as the motivating realization. Treating dark matter, dark energy, baryons, and radiation as an autonomous dynamical system, we show that exact stasis requires exponential slopes along the trajectory, and that running slopes give exact stasis or a drifting quasi-stasis depending on whether the running is integrable. The constant abundance solutions are the stationary solutions of coupled quintessence, which we read as stasis epochs with computable lifetimes and exits. Anchoring the cosmology to the measured abundances at matter-radiation equality and today, we show that the stasis region for this model cannot accelerate for any initial conditions, and that the total equation of state is never phantom although the effective dark energy of a ΛCDM fit can appear so. For the Dark Dimension, capture into stasis in the future is excluded for geometric sources of the potential once dark fifth-force bounds are imposed, and dark matter production from the Standard Model brane supports a further stasis which the standard scenario does not reach. The stasis solutions provide analytic exclusions of the parameter space which do not depend on initial conditions.
ER -