{
  "abstract": "The Weak Gravity Conjecture (WGC) is a swampland criterion of long standing: any consistent theory of quantum gravity must contain a charged particle whose charge-to-mass ratio exceeds that of an extremal black hole, so that gravity remains the weakest force. Quasinormal modes of a near-extremal black hole are poles of a retarded Green’s function of the conformal quantum mechanics living on the near-horizon AdS $$_2$$ 2 throat, and their damping rate is bounded from below by the Hawking temperature. We show that this pairing fixes the WGC bound in closed form. Only two numbers survive from the bulk geometry, the AdS $$_2$$ 2 radius $$L_2$$ L 2 and the electric-field parameter $$e_d$$ e d of the throat, and the conjecture reads $$q/m \\ge L_2/e_d$$ q / m ≥ L 2 / e d . We evaluate this quantity for two backgrounds that fall outside the Reissner–Nordström idealisation in different ways: static spherically symmetric black holes in dRGT massive gravity, and electrically charged black holes in Einstein–ModMax non-linear electrodynamics, the latter taken throughout in its purely electric sector, where the pseudoscalar invariant G vanishes. For dRGT the massive-gravity couplings do not drop out. The bound becomes $$q/m \\ge \\sqrt{D/A}$$ q / m ≥ D / A with $$A = 1+\\zeta +\\Lambda r_+^2 + 2\\gamma _g r_+$$ A = 1 + ζ + Λ r + 2 + 2 γ g r + and $$D = 1+\\zeta +2\\Lambda r_+^2+3\\gamma _g r_+$$ D = 1 + ζ + 2 Λ r + 2 + 3 γ g r + , so the deviation from the Reissner–Nordström value is second order in the graviton mass and is positive whenever $$\\Lambda r_+ + \\gamma _g > 0$$ Λ r + + γ g > 0 . For Einstein–ModMax the duality parameter enters through the charge normalisation of the non-linear displacement field, giving $$q/m \\ge e^{\\gamma /2}$$ q / m ≥ e γ / 2 , which coincides identically with the charge-to-mass ratio $$Q_\\textrm{ext}/M_\\textrm{ext}$$ Q ext / M ext of the extremal solution. That coincidence is a sharp check on the whole construction. We then relax exact extremality, minimal coupling and the two-derivative truncation, and follow how each relaxation feeds back into $$L_2$$ L 2 and $$e_d$$ e d . Every closed form is cross-checked twice, once symbolically and once against a Runge–Kutta integration of the full radial Klein–Gordon equation that extracts the conformal weight from the horizon exponents without using the throat approximation; the two agree to eleven digits.",
  "abstract_shown": true,
  "affiliations": [
    "Damghan University",
    "Khazar University",
    "Eastern Mediterranean University"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 3,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Saeed Noori Gashti",
      "orcid": "0000-0001-7844-2640"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Behnam Pourhassan",
      "orcid": "0000-0003-1338-7083"
    },
    {
      "affs": [
        2
      ],
      "name": "İzzet Sakallı",
      "orcid": "0000-0001-7827-9476"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/4x32mhkavq5ac.bib",
  "cited_by": 0,
  "doi": "10.1140/epjc/s10052-026-16427-z",
  "fulltext_url": null,
  "id": "4x32mhkavq5ac",
  "issns": [
    "1434-6044",
    "1434-6052"
  ],
  "landing_url": "https://link.springer.com/10.1140/epjc/s10052-026-16427-z",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "3106|Black Holes and Theoretical Physics"
    ]
  ],
  "openalex": "W7166738114",
  "pdf_url": "https://link.springer.com/content/pdf/10.1140/epjc/s10052-026-16427-z.pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-05",
  "publisher": "Springer Science and Business Media LLC",
  "ris": "https://research.draconitic.com/paper/4x32mhkavq5ac.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:04Z",
      "native_id": "10.1140/epjc/s10052-026-16427-z",
      "source": "crossref",
      "url": "https://link.springer.com/10.1140/epjc/s10052-026-16427-z"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "openalex:3106|Black Holes and Theoretical Physics",
      "subfield": "high-energy"
    }
  ],
  "title": "CFT constraints on the weak gravity conjecture",
  "title_text": "CFT constraints on the weak gravity conjecture",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:18:04Z",
  "url": "https://research.draconitic.com/paper/4x32mhkavq5ac",
  "venue": "The European Physical Journal C",
  "versions": []
}