{
  "abstract": "5We study homogeneous cosmological perturbations in the quadratic model $F(R,\\mathcal G)=R+αR^2+β\\mathcal G^2$. Linearization of the modified Friedmann equation together with dust conservation yields a second-order equation for the homogeneous Hubble perturbation, or equivalently a third-order equation for the matter contrast. We then restrict the asymptotic analysis to backgrounds that satisfy the zeroth-order equations of the same quadratic theory. Besides the low-curvature dust branch, which approaches $H=2/(3t)$, the model admits a nontrivial vacuum de Sitter solution with $βH_{\\rm dS}^6=1/96$. Its homogeneous curvature modes are stable only when $α<-1/(6H_{\\rm dS}^2)$. At high curvature the background equation also admits a vacuum big-rip asymptotic branch beginning with $H=7/(t_s-t)$; the first corrections are fixed by the quadratic couplings. The corresponding $\\mathcal G^2$-dominated perturbation has one divergent homogeneous mode. The simultaneous Einstein limit is taken only as a consistency check and recovers the standard dust behavior.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.03752",
  "author_total": 4,
  "authors": [
    {
      "name": "Francisco Tello-Ortiz"
    },
    {
      "name": "B. Mishra"
    },
    {
      "name": "Y. Gómez-Leyton"
    },
    {
      "name": "Jean Báez Cuevas"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/cswt5k4w3tk8r.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.03752",
  "fulltext_url": null,
  "id": "cswt5k4w3tk8r",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.03752",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "gr-qc"
    ],
    [
      "arxiv",
      "hep-th"
    ],
    [
      "openalex",
      "3103|Cosmology and Gravitation Theories"
    ]
  ],
  "openalex": "W7220680078",
  "pdf_url": "https://arxiv.org/pdf/2610.03752",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-01",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/cswt5k4w3tk8r.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:27:01Z",
      "native_id": "2610.03752",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.03752"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:gr-qc",
      "subfield": "gravitation"
    },
    {
      "field": "physics",
      "origin": "arxiv:hep-th",
      "subfield": "high-energy"
    }
  ],
  "title": "On-shell Homogeneous Curvature Modes in Quadratic $F(R,\\mathcal G)$ Cosmology",
  "title_text": "On-shell Homogeneous Curvature Modes in Quadratic F(R,𝒢) Cosmology",
  "type": "preprint",
  "updated_at": "2026-10-30T12:27:01Z",
  "url": "https://research.draconitic.com/paper/cswt5k4w3tk8r",
  "venue": "arXiv",
  "versions": []
}