{
  "abstract": "Inflationary magnetogenesis provides a promising mechanism for generating primordial large-scale magnetic fields, but faces challenges such as the strong coupling problem and backreaction issues. In this paper, we extend the Ratra model by introducing a coupling between the electromagnetic field and the background geometry, parameterized as $K(R)I^2(ϕ)$. Starting from a general action with $f^2(R,ϕ)F_{μν}F^{μν}$, we adopt $f^2(R,ϕ)=K(R)I^2(ϕ)$ as a concrete realization. Rather than focusing on the slow-roll inflationary stage (which reduces to the standard Ratra scenario), we concentrate on the post-inflationary reheating epoch, where the broken-power-law evolution of the scale factor and coupling function across the inflation-to-reheating transition allows us to derive analytic expressions for the magnetic and electric energy density spectra. Three key theoretical constraints are imposed on the model parameter space: the strong coupling condition, the backreaction constraint, and the CMB isotropy requirement. We obtain predictions for the present-day magnetic field strength $B_0$ and coherence length $L_{c0}$ for various combinations of the inflationary energy scale $H_f$ and the reheating temperature $T_r$. By comparing with observational constraints from radio observations and Fermi-LAT gamma-ray data, we demonstrate that the inflationary energy scale $H_f$, the reheating temperature $T_r$, the parameter $β$, and the e-folding numbers $N_f$, $N_r$ must satisfy stringent joint constraints. This work provides a viable theoretical framework for inflationary magnetogenesis that simultaneously satisfies theoretical consistency conditions and current observational bounds, with the reheating-stage nonlinear MHD evolution serving as a crucial ingredient for producing observationally compatible magnetic fields.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.01977",
  "author_total": 4,
  "authors": [
    {
      "name": "Shuang Liu"
    },
    {
      "name": "Bo-yu Zhao"
    },
    {
      "name": "Yu Li"
    },
    {
      "name": "Yao-chuan Wang"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/13fhmhyz65n9w.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.01977",
  "fulltext_url": null,
  "id": "13fhmhyz65n9w",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.01977",
  "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",
      "astro-ph.CO"
    ],
    [
      "arxiv",
      "gr-qc"
    ],
    [
      "openalex",
      "3103|Cosmology and Gravitation Theories"
    ]
  ],
  "openalex": "W7207709428",
  "pdf_url": "https://arxiv.org/pdf/2609.01977",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-09",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/13fhmhyz65n9w.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:20:12Z",
      "native_id": "2609.01977",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.01977"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    },
    {
      "field": "physics",
      "origin": "arxiv:gr-qc",
      "subfield": "gravitation"
    }
  ],
  "title": "Inflationary Magnetogenesis with $f(R,ϕ)$ Coupling",
  "title_text": "Inflationary Magnetogenesis with f(R,ϕ) Coupling",
  "type": "preprint",
  "updated_at": "2026-10-30T12:20:12Z",
  "url": "https://research.draconitic.com/paper/13fhmhyz65n9w",
  "venue": "arXiv",
  "versions": []
}