{
  "abstract": "We present a model of slow-roll inflation in metric-affine gravity, where the connection is independent of the metric. We require that the Einstein-Hilbert term is the only operator that breaks three out of four shift-symmetries of the connection, and impose them on the metric-affine Starobinsky term $αR(Γ)^2$. This replaces it by $α\\mathring{R}^2$, the square of the invariant part of the scalar curvature. The theory propagates only the graviton and one healthy scalar, the metric-affine $\\mathring{R}^2$ scalaron. Its potential approaches a plateau polynomially, $U\\simeq U_0(1-μ^2/χ^2)$, with $μ=\\sqrt{6}\\,M_P$ fixed by the curvature of the connection. Once $α\\simeq2\\times10^{8}$ is set by the scalar amplitude, the model has no free parameters. It predicts $n_s\\simeq1-3/(2N_*)$ and $r\\simeq2\\sqrt3\\,N_*^{-3/2}$ at leading order in $N_*$, and $n_s=0.968$--$0.974$ and $r=0.011$-$0.008$ with exact slow-roll for $N_*=50$-$60$ $e$-folds. These values agree with current data, and $r$ is within reach of the next generation of $B$-mode measurements.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.23522",
  "author_total": 1,
  "authors": [
    {
      "name": "Christian Dioguardi"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/9x04bb8y9tcjx.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.23522",
  "fulltext_url": null,
  "id": "9x04bb8y9tcjx",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.23522",
  "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-ph"
    ],
    [
      "openalex",
      "3103|Cosmology and Gravitation Theories"
    ]
  ],
  "openalex": "W7222917827",
  "pdf_url": "https://arxiv.org/pdf/2610.23522",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-16",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/9x04bb8y9tcjx.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:30:32Z",
      "native_id": "2610.23522",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.23522"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    },
    {
      "field": "physics",
      "origin": "arxiv:gr-qc",
      "subfield": "gravitation"
    },
    {
      "field": "physics",
      "origin": "arxiv:hep-ph",
      "subfield": "high-energy"
    }
  ],
  "title": "The metric-affine $\\mathring{R}^2$ scalaron: parameter-free inflation",
  "title_text": "The metric-affine mathringR^2 scalaron: parameter-free inflation",
  "type": "preprint",
  "updated_at": "2026-10-30T12:33:28Z",
  "url": "https://research.draconitic.com/paper/9x04bb8y9tcjx",
  "venue": "arXiv",
  "versions": []
}