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Varying fundamental constants meet Hubble

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arxiv 2309.12083 v1 pith:NX4VGUC7 submitted 2023-09-21 astro-ph.CO gr-qchep-th

Varying fundamental constants meet Hubble

classification astro-ph.CO gr-qchep-th
keywords constantshubblephysicalconstantcosmologicalelectronfundamentalmass
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved
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Fundamental physical constants need not be constant, neither spatially nor temporally. -- This seeming simple statement has profound implications for a wide range of physical processes and interactions, and can be probed through a number of observations. In this chapter, we highlight how CMB measurements can constrain variations of the fine-structure constant and the electron rest mass during the cosmological recombination era. The sensitivity of the CMB anisotropies to these constants arises because they directly affect the cosmic ionization history and Thomson scattering rate, with a number of subtle atomic physics effects coming together. Recent studies have revealed that variations of the electron rest mass can indeed alleviate the Hubble tension, as we explain here. Future opportunities through measurements of the cosmological recombination radiation are briefly mentioned, highlighting how these could provide an exciting avenue towards uncovering the physical origin of the Hubble tension experimentally.

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Cited by 6 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. The $H_0$ world cup. II. A comprehensive competition between proposed Hubble tension solutions

    astro-ph.CO 2026-07 conditional novelty 6.0

    Against a common 2025-26 dataset (Planck PR4, ACT DR6, SPT-3G, DESI DR2, Pantheon+), early dark energy and early modified gravity models win the H0 competition (~3σ residual tension), while radiation and late-time sol...

  2. The $H_0$ World Cup. I. Summary of the baseline group stage results

    astro-ph.CO 2026-07 conditional novelty 5.0

    In a systematic head-to-head analysis, early dark energy and early modified gravity models reduce the Hubble tension to about 3σ and are favored over ΛCDM, while radiation and late-time alternatives are not.

  3. Hubble tension: a short review of theoretical explanations

    astro-ph.CO 2026-07 accept novelty 4.0

    A comprehensive review finds no theoretical Hubble-tension solution yet passes all consistency tests; new early-dark-energy chains reach high H0 only when the SH0ES calibration is added.

  4. Cosmological Viability of Exponential Infrared $f(T)$ Gravity

    astro-ph.CO 2026-06 unverdicted novelty 4.0

    Exponential IR f(T) gravity Model I alleviates Hubble tension but is disfavoured by combined Planck/ACT/SPT+DESI+Pantheon+ data; Model II is ruled out because background constraints force unphysical shifts in CMB parameters.

  5. The Hubble tension: A decade review

    astro-ph.CO 2026-06 conditional novelty 3.0

    Pure early or late fixes to the Hubble tension are tightly constrained; remaining options are combined early-late interacting dark energy or new physics at the local-to-homogeneous transition.

  6. The Hubble tension: A decade review

    astro-ph.CO 2026-06 unverdicted novelty 2.0

    A review summarizing the Hubble tension as a persistent crisis and discussing resolutions via interacting dark energy models that combine early-time and late-time modifications.