{
  "abstract": "We determine the decay rate $Γ$ of a scalar particle bound to a light nucleus, numerically and analytically. As a model system, we consider a negatively charged kaon in the ground state of a hydrogen-like ion decaying into charged and neutral scalar pions, $K^-\\to π^-π^0$. All particles are assumed point-like; the nucleus is infinitely heavy. The partial wave expansion converges slowly, as in a recent analysis of the bound-muon decay. To overcome this difficulty, we introduce a subtraction method: the free $π^-$ contribution is evaluated separately, while the partial-wave sum is used only for the Coulomb distortion. The ratio of bound-to-free decay rates, $Γ/Γ_0$, is found for light nuclei, $1\\leq Z\\leq 10$. The numerical calculation is complemented by a diagrammatic small-$αZ$ expansion. We find $ Γ/Γ_0 = 1-(αZ)^2/2 + 17(αZ)^4/24 +\\mathcal{O}((αZ)^5)$, in agreement with the all-orders numerical calculation at low $Z$.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.37651",
  "author_total": 2,
  "authors": [
    {
      "name": "Andrzej Czarnecki"
    },
    {
      "name": "Artem O. Davydov"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/4mqzbfqnbv1jj.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.37651",
  "fulltext_url": null,
  "id": "4mqzbfqnbv1jj",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.37651",
  "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",
      "hep-ph"
    ],
    [
      "openalex",
      "3106|Particle physics theoretical and experimental studies"
    ]
  ],
  "openalex": "W7214919932",
  "pdf_url": "https://arxiv.org/pdf/2609.37651",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-29",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/4mqzbfqnbv1jj.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:25:31Z",
      "native_id": "2609.37651",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.37651"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:hep-ph",
      "subfield": "high-energy"
    }
  ],
  "title": "Bound-state decay of a charged scalar particle in an external Coulomb field",
  "title_text": "Bound-state decay of a charged scalar particle in an external Coulomb field",
  "type": "preprint",
  "updated_at": "2026-10-30T12:25:31Z",
  "url": "https://research.draconitic.com/paper/4mqzbfqnbv1jj",
  "venue": "arXiv",
  "versions": []
}