The Equivalence Principle in the Dark Sector in light of DESI
Abstract
Recent measurements of the distribution of galaxies by the Dark Energy Spectroscopic Instrument (DESI) are in mild tension with a standard Λ-Cold Dark Matter cosmological model inferred from the anisotropies of the Cosmic Microwave Background (CMB) when extrapolated to low redshifts. Several solutions to explain this discrepancy in terms of new physics have been put forward, notably from new dynamics in a complex Dark Sector. Here we report on a resolution to this discrepancy that postulates that the inertial and gravitational masses of dark matter particles are not the same. Our best fit to CMB data combined either with Baryon Acoustic Oscillation (BAO) and Full Shape (FS) data from DESI DR1 (Data Release 1), or with BAO DR2 data alone, suggests the presence of a new long-range force in the Dark Sector with strength of $β\sim 0.5\% $ relative to gravity, at the ∼ 2.5σ level. A preliminary analysis combining FS DR1 and BAO DR2 data confirms the statistical power of DR2 and raises the evidence for dark forces to ∼ 3σ, albeit ignoring the not yet available cross-correlation between the two datasets.
Related
- Galactic warps constrain equivalence-principle violation in the dark sector
- Exploring the Limits: Neutrino Mass and Interacting Dark Sector in the DESI Era
- Reassessing Evidence for Dark-Sector Interactions with Dynamical Dark Energy and DESI DR2
- Tests of equivalence principle violation in doubly coupled dark energy
- Observational constraints on fractional holographic dark energy in the light of DESI DR2
BibTeX
@misc{clini2026equivalence,
title = {{The Equivalence Principle in the Dark Sector in light of DESI}},
author = {Andrea Clini and Pierre Zhang and Emanuele Castorina and Maria Archidiacono},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.17423},
eprint = {2609.17423},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.17423},
}
RIS
TY - UNPB
TI - The Equivalence Principle in the Dark Sector in light of DESI
AU - Andrea Clini
AU - Pierre Zhang
AU - Emanuele Castorina
AU - Maria Archidiacono
PY - 2026
DA - 2026/09/15
PB - arXiv
DO - 10.48550/arxiv.2609.17423
UR - https://arxiv.org/abs/2609.17423
AB - Recent measurements of the distribution of galaxies by the Dark Energy Spectroscopic Instrument (DESI) are in mild tension with a standard Λ-Cold Dark Matter cosmological model inferred from the anisotropies of the Cosmic Microwave Background (CMB) when extrapolated to low redshifts. Several solutions to explain this discrepancy in terms of new physics have been put forward, notably from new dynamics in a complex Dark Sector. Here we report on a resolution to this discrepancy that postulates that the inertial and gravitational masses of dark matter particles are not the same. Our best fit to CMB data combined either with Baryon Acoustic Oscillation (BAO) and Full Shape (FS) data from DESI DR1 (Data Release 1), or with BAO DR2 data alone, suggests the presence of a new long-range force in the Dark Sector with strength of $β\sim 0.5\% $ relative to gravity, at the ∼ 2.5σ level. A preliminary analysis combining FS DR1 and BAO DR2 data confirms the statistical power of DR2 and raises the evidence for dark forces to ∼ 3σ, albeit ignoring the not yet available cross-correlation between the two datasets.
ER -