Dark Radiation Sticks Together: Dark QCD and the Hubble Tension
Abstract
We introduce a model of dark matter charged under a new confining gauge group akin to the Standard Model's quantum chromodynamics (QCD). The fermionic sector contains both heavy and light quark-like fermions charged under the dark QCD. As the Universe cools, the gauge force confines and dark radiation transitions from free particles to low-mass dark pions. This form of dark radiation behaves as an imperfect fluid with nonzero viscosity. If the confinement occurs at the MeV scale, the model can alleviate the tension between early- and late-time measurements of the Hubble parameter, with a Bayesian posterior of H0 = 71.60± 0.63 km/s/Mpc and a 3σ residual tension across Planck, ACT, BBN, Pantheon+, DESI DR2, and SH0ES. In the late Universe, the heavy dark matter can evade existing constraints on dark matter self-interactions while containing a rich phenomenology that may be accessible in future observations.
Related
- Revisiting the Hubble tension with an inverse power-law early dark energy
- Resolving the Hubble Tension in the Early Dark Energy Framework with JWST and DESI Data
- Four-Sector Cosmology: A CPT-Symmetric Resolution of the Hubble Tension, Dark Matter, and Dark Energy
- Unified dark sector and Hubble-tension alleviation in scalar-vector-tensor gravity
- Alleviating the Hubble Tension Using Coupled Dark Energy - Dark Matter Interaction
BibTeX
@misc{buckley2026dark,
title = {{Dark Radiation Sticks Together: Dark QCD and the Hubble Tension}},
author = {Matthew R. Buckley and Nicolas Fernandez and Eric Putney},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.16120},
eprint = {2609.16120},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.16120},
}
RIS
TY - UNPB
TI - Dark Radiation Sticks Together: Dark QCD and the Hubble Tension
AU - Matthew R. Buckley
AU - Nicolas Fernandez
AU - Eric Putney
PY - 2026
DA - 2026/09/14
PB - arXiv
DO - 10.48550/arxiv.2609.16120
UR - https://arxiv.org/abs/2609.16120
AB - We introduce a model of dark matter charged under a new confining gauge group akin to the Standard Model's quantum chromodynamics (QCD). The fermionic sector contains both heavy and light quark-like fermions charged under the dark QCD. As the Universe cools, the gauge force confines and dark radiation transitions from free particles to low-mass dark pions. This form of dark radiation behaves as an imperfect fluid with nonzero viscosity. If the confinement occurs at the MeV scale, the model can alleviate the tension between early- and late-time measurements of the Hubble parameter, with a Bayesian posterior of H_0 = 71.60± 0.63 km/s/Mpc and a 3σ residual tension across Planck, ACT, BBN, Pantheon+, DESI DR2, and SH0ES. In the late Universe, the heavy dark matter can evade existing constraints on dark matter self-interactions while containing a rich phenomenology that may be accessible in future observations.
ER -