Dark Radiation Sticks Together: Dark QCD and the Hubble Tension

arXiv:2609.16120 · hep-ph, astro-ph.CO · Submitted 2026-09-14 · Read on arXiv

hep-ph, astro-ph.CO

Submitted: 2026-09-14

Updated: 2026-09-14

Comments: 19 pages, 6 figures

Code: https://github.com/lesgourg/class

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

Terminology

• Hubble Tension — 22× in this paper · explained in 9 episodes
• Decoupling — 6× in this paper · explained in 2 episodes
• Clustering — 5× in this paper · explained in 2 episodes
• Matter Power Spectrum — 5× in this paper · explained in 2 episodes
• Benchmark — 3× in this paper · explained in 2 episodes
• Trace — 3× in this paper · explained in 2 episodes
• alpha — 3× in this paper · explained in 1 episode
• Abundance — 2× in this paper · explained in 1 episode
• Big Bang Nucleosynthesis — 2× in this paper
• Cosmic Microwave Background — 2× in this paper
• Gravitational Lensing — 2× in this paper · explained in 2 episodes
• Reheating — 2× in this paper · explained in 2 episodes
• ACT Data — 1× in this paper · explained in 1 episode
• Anisotropy — 1× in this paper · explained in 3 episodes
• Momentum transfer — 1× in this paper · explained in 2 episodes
• Symmetry Breaking — 1× in this paper · explained in 3 episodes
• Weak Lensing — 1× in this paper · explained in 2 episodes

Sources

• The CosmoVerse White Paper: Addressing observational tensions in cosmology with systematics and fundamental physics
• A Comprehensive Measurement of the Local Value of the Hubble Constant with 1 km/s/Mpc Uncertainty from the Hubble Space Telescope and the SH0ES Team
• The Local Distance Network: a community consensus report on the measurement of the Hubble constant at 1% precision
• Planck 2018 results. VI. Cosmological parameters
• SPT-3G D1: CMB temperature and polarization power spectra and cosmology from 2019 and 2020 observations of the SPT-3G Main field
• The Hubble Hunter's Guide
• The $H_0$ Olympics: A fair ranking of proposed models
• The H 0 World Cup. I. Summary of the baseline group stage results
• The H 0 world cup. II. A comprehensive competition between proposed Hubble tension solutions
• Evidence for dark matter interactions in cosmological precision data?
• The trouble with $H_0$
• A Step in Understanding the Hubble Tension
• The Hubble Tension as a Hint of Leptogenesis and Neutrino Mass Generation
• A Step in Understanding the $S_8$ Tension
• Dark Radiation from Neutrino Mixing after Big Bang Nucleosynthesis
• On the dark radiation role in the Hubble constant tension
• The weak, the strong and the ugly -- A comparative analysis of interacting stepped dark radiation
• Comprehensive Constraints on Dark Radiation Injection After BBN
• Stepping into the Forest: Confronting Interacting Radiation Models for the Hubble Tension with Lyman-$\alpha$ Data
• Reduced Hubble Tension in Dark Radiation Models after DESI 2024

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