{
  "abstract": "Metastable cosmic strings provide a cosmological interpretation of the nanohertz stochastic gravitational wave background reported by Pulsar Timing Array (PTA) experiments. We revisit this scenario in a minimal dark-sector gauge theory, in which a complex Higgs doublet breaks $\\mathrm{SU}(2)\\times\\mathrm{U}(1)\\to\\mathrm{U}(1)_{\\rm IR}$ at a single symmetry-breaking scale. This one-scale setup predicts metastable $Z$-strings whose endpoints are monopole-like defects, and whose zero-temperature decay rate is controlled by the gauge couplings and mass ratios. We show that, once the string-forming transition occurs in a thermal plasma, the dominant decay channel is not the zero-temperature monopole nucleation but thermally induced nucleation on the string worldsheet. We determine the nucleation temperature $T_{\\rm nuc}$, which we \\rev{adopt as the reference string-formation scale}, from the one-loop finite-temperature effective potential with daisy resummation, and use it to evaluate the worldsheet bounce action throughout the model parameter space. \\rev{Requiring a PTA-compatible gravitational wave} signal selects a narrow region in the model parameter space, in the $(\\sin^2θ_w,\\sqrtβ)$ plane, where $θ_w$ is the dark-sector weak mixing angle and $β\\equiv M_Φ^2/M_{Z}^2$ is the squared Higgs-to-$Z$ mass ratio. Thermal effects modify the zero-temperature picture significantly, shifting the PTA-compatible region towards lower values of the dark fine-structure constant $α'$ and larger values of the monopole-to-string-tension ratio $κ$.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2606.02689",
  "author_total": 4,
  "authors": [
    {
      "name": "Arturo de Giorgi"
    },
    {
      "name": "James Ingoldby"
    },
    {
      "name": "Valentin V. Khoze"
    },
    {
      "name": "Jessica Turner"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/0ekvw6j64hp10.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2606.02689",
  "fulltext_url": null,
  "id": "0ekvw6j64hp10",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2606.02689",
  "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",
      "hep-ph"
    ],
    [
      "arxiv",
      "hep-th"
    ],
    [
      "openalex",
      "3106|Particle physics theoretical and experimental studies"
    ]
  ],
  "openalex": "W7163357848",
  "pdf_url": "https://arxiv.org/pdf/2606.02689",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-05",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/0ekvw6j64hp10.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:27:01Z",
      "native_id": "2606.02689",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2606.02689"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    },
    {
      "field": "physics",
      "origin": "arxiv:hep-ph",
      "subfield": "high-energy"
    }
  ],
  "title": "Thermal Metastable Strings in One-Scale Models and Gravitational Waves",
  "title_text": "Thermal Metastable Strings in One-Scale Models and Gravitational Waves",
  "type": "preprint",
  "updated_at": "2026-10-30T12:27:01Z",
  "url": "https://research.draconitic.com/paper/0ekvw6j64hp10",
  "venue": "arXiv",
  "versions": []
}