If the Hubble tension reflects new physics, the difficulties for primordial black hole models from ultra-slow-roll inflation grow, according to this paper.

The paper

The paper's details are OpenAlex's; the citation count is OpenAlex's, 15 Oct 2026. The line on the paper is machine-written, as noted under Why it matters.

Why it matters

Written by Claude (claude-sonnet-5-5) on 15 Oct 2026 from the paper's abstract (as the publisher's record at Crossref publishes it) and its OpenAlex record. Machine-written context to help a reader: it is not evidence, it moves no number, and it may be wrong. The quoted sentence is the claim; where it stands is computed from the record. If it misreads the paper, tell the stewards.

The story so far

1. 1

   What the authors did

   The authors fitted state-of-the-art CMB data (including ACT and the South Pole Telescope) plus DESI DR2 baryon acoustic oscillation data, comparing Λ cold dark matter with an axionlike early dark energy model, and constrained the spectral running.

   Machine-written from the paper's abstract, as noted under Why it matters.

2. 2

   What they found

   • Ultra-slow-roll models with an inflection point near CMB scales predict a negative spectral running, larger in magnitude for heavier primordial black holes, which conflicts with hints of positive running from ACT.
   • For most dataset combinations, moving from Λ cold dark matter to early dark energy increases the inferred running, because extra damping must be offset by more small-scale power.
   • The authors say that inflationary model selection using CMB-inferred parameters such as n_s and α_s may be premature until the pre-recombination expansion history is understood.

   Machine-written from the paper's abstract, as noted under Why it matters.

3. 3

   What has been checked on Ecdysis

   Exuvia registered it on 15 October 2026. Its credence, the record's estimate that it holds, is 0.55 on a scale from 0 (refuted) to 1 (established): where it started, as every claim from the literature does. Only independent evidence moves it.

What would check it

How sure is the record?

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What would prove it wrong

Refuted if an independent analysis shows that including early‑dark‑energy physics to resolve the Hubble tension makes ultra‑slow‑roll primordial black hole models more compatible with current CMB observations (e.g., by reducing the inferred spectral running or improving the fit to small‑scale power).

The test as Exuvia registered it on 15 Oct 2026, written from the paper's words. A conceptual claim's test names its refuter in words: it is checked by argument.

The wider literature

Other claims from the same paper

• uncheckedFor most dataset combinations, adding early dark energy to the standard model raises the inferred spectral running α_s, offsetting extra small-scale damping.“For most dataset combinations, moving from Λ cold dark matter to EDE increases the inferred α s : once the acoustic angular scale θ s is fixed, EDE increases the diffusion-to-acoustic angular scale r…”

Headlines are machine-written from the paper's abstract, or from the quote and the paper's title where no abstract is open; each claim's own words are quoted beneath its headline.