{
  "abstract": "Finite-temperature quantum-gravitational corrections to the cosmological constant introduce two additional density parameters, $Ω_{Λ_2}$ and $Ω_{Λ_3}$, the associated terms of which scale as $a^{-4}$ and $a^{-2}$, respectively. In previous work (Papers I and II), these parameters were studied using machine-learning methods that identified a best-fit point. Here we complete the picture with two complementary analyses. First, we perform a Bayesian MCMC analysis using a modified version of \\textsc{class} against the Planck 2018 likelihoods. This tells us what the data can constrain once all parameter uncertainties have been marginalized over. Both parameters are consistent with zero, with $Ω_{Λ_3}$ constrained only from one side. Second, we build a CMB pipeline from scratch, following Weinberg's kinetic-theory formulation and validating it against \\textsc{class}. This allows us to study the underlying physics. The response analysis carried out with it shows that $Ω_{Λ_3}$ is almost entirely absorbed by a shift in $h$ over the well-measured acoustic multipoles. The part of the signal that cannot be absorbed resides at low $\\ell$, where cosmic variance dominates. Meanwhile, the $Ω_{Λ_2}$ signature is nearly degenerate with the overall amplitude of the spectrum. The effects of both parameters on the CMB power spectrum are small, since they represent higher-order thermal corrections to the cosmological constant. The resulting constraints are correspondingly weak: the induced shifts are largely absorbed by degeneracies with $h$ and with the overall normalization of the spectrum. This is the reason why neither parameter is detected.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.05435",
  "author_total": 1,
  "authors": [
    {
      "name": "I. Y. Park"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/ep6xchxg39g12.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.05435",
  "fulltext_url": null,
  "id": "ep6xchxg39g12",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.05435",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.CO"
    ],
    [
      "arxiv",
      "gr-qc"
    ],
    [
      "arxiv",
      "hep-th"
    ],
    [
      "openalex",
      "3103|Cosmology and Gravitation Theories"
    ]
  ],
  "openalex": "W7220686437",
  "pdf_url": "https://arxiv.org/pdf/2610.05435",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-04",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/ep6xchxg39g12.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:27:01Z",
      "native_id": "2610.05435",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.05435"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    },
    {
      "field": "physics",
      "origin": "arxiv:gr-qc",
      "subfield": "gravitation"
    },
    {
      "field": "physics",
      "origin": "arxiv:hep-th",
      "subfield": "high-energy"
    }
  ],
  "title": "Kinetic-theory derivation and Bayesian analysis of the finite-temperature shifted CMB power spectrum",
  "title_text": "Kinetic-theory derivation and Bayesian analysis of the finite-temperature shifted CMB power spectrum",
  "type": "preprint",
  "updated_at": "2026-10-30T12:27:01Z",
  "url": "https://research.draconitic.com/paper/ep6xchxg39g12",
  "venue": "arXiv",
  "versions": []
}