Evolving dark sector and the dark dimension scenario
- 1Princeton University
- 2University of Oxford
- 3Harvard University
Abstract
String theory naturally leads to the expectation that dark energy is not stable, and may be evolving as captured by the Swampland de Sitter conjectures. Moreover, motivated by the distance conjecture, a unification of dark sector has been proposed, where the smallness of dark energy leads to one extra dimension of micron size with dark matter being the Kaluza-Klein graviton excitations in this extra dimension. We consider the natural possibility that the radius of the dark dimension varies as the energy decreases, leading to the variation of the dark matter mass. This correlates the variation of the dark energy with the variation of the dark matter mass as they depend on the variations of a scalar field ϕ controlling the radius of the extra dimension. A simple realization of this idea for small range of ϕ is adequately captured by choosing a potential which is locally of the form V = V 0 exp ( − c ϕ ) and dark matter mass m DM = m 0 exp ( − c ′ ϕ ) as was proposed in [1]. We find excellent agreement with recent experimental data from DESI DR2 combined with SN measurements (from DES, Union3 or Pantheon+) and reproduces the same significance as Chevallier–Polarski–Linder parametrization with the added benefit of providing a natural explanation for the apparent phantom behavior ( w < − 1 ) reported by DESI and DES based on a physical model. DESI and SN datasets independently favor nonzero values of c ′ and c , respectively, both lying within the expected O ( 1 ) range suggested by the Swampland criteria. Moreover, our best fit value c ′ ≃ 0.05 ± 0.01 is remarkably consistent with the experimental upper bound of c ′ ≲ 0.2 demanded by the lack of detection of fifth force in the dark sector.
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BibTeX
@article{bedroya2026evolving,
title = {{Evolving dark sector and the dark dimension scenario}},
author = {Alek Bedroya and Georges Obied and Cumrun Vafa and David H. Wu},
journal = {Physical review. D/Physical review. D.},
year = {2026},
month = aug,
doi = {10.1103/1rsq-cv2m},
url = {https://doi.org/10.1103/1rsq-cv2m},
note = {CC BY},
}
RIS
TY - JOUR
TI - Evolving dark sector and the dark dimension scenario
AU - Alek Bedroya
AU - Georges Obied
AU - Cumrun Vafa
AU - David H. Wu
PY - 2026
DA - 2026/08/03
JO - Physical review. D/Physical review. D.
DO - 10.1103/1rsq-cv2m
UR - https://doi.org/10.1103/1rsq-cv2m
AB - String theory naturally leads to the expectation that dark energy is not stable, and may be evolving as captured by the Swampland de Sitter conjectures. Moreover, motivated by the distance conjecture, a unification of dark sector has been proposed, where the smallness of dark energy leads to one extra dimension of micron size with dark matter being the Kaluza-Klein graviton excitations in this extra dimension. We consider the natural possibility that the radius of the dark dimension varies as the energy decreases, leading to the variation of the dark matter mass. This correlates the variation of the dark energy with the variation of the dark matter mass as they depend on the variations of a scalar field ϕ controlling the radius of the extra dimension. A simple realization of this idea for small range of ϕ is adequately captured by choosing a potential which is locally of the form V = V 0 exp ( − c ϕ ) and dark matter mass m DM = m 0 exp ( − c ′ ϕ ) as was proposed in [1]. We find excellent agreement with recent experimental data from DESI DR2 combined with SN measurements (from DES, Union3 or Pantheon+) and reproduces the same significance as Chevallier–Polarski–Linder parametrization with the added benefit of providing a natural explanation for the apparent phantom behavior ( w < − 1 ) reported by DESI and DES based on a physical model. DESI and SN datasets independently favor nonzero values of c ′ and c , respectively, both lying within the expected O ( 1 ) range suggested by the Swampland criteria. Moreover, our best fit value c ′ ≃ 0.05 ± 0.01 is remarkably consistent with the experimental upper bound of c ′ ≲ 0.2 demanded by the lack of detection of fifth force in the dark sector.
SN - 2470-0010
SN - 2470-0029
SN - 2470-0037
ER -