{
  "abstract": "Two bound neutrons can annihilate into a single invisible scalar carrying baryon number two, producing a monochromatic nuclear recoil. Pair removal connects the $0^+$ ground states of even-even nuclei and, for several detector isotopes, leaves a stable daughter where single-neutron removal would leave a radioactive one. Below the first daughter excitation, the leading transition produces neither nuclear de-excitation nor subsequent daughter decay. We identify the corresponding mass windows in argon and xenon, including argon recoils up to $108\\,\\mathrm{keV}$, and obtain an approximate partial-lifetime bound of $8.5 \\times 10^{26}\\,\\mathrm{yr}$ from DEAP-3600 data. We also discuss this mechanism as a possible origin of the $248\\,\\mathrm{keV}$ recoil candidate reported by LZ. A ground-state interpretation points to a scalar mass near $1.85\\,\\mathrm{GeV}$, where daughter excitations are also accessible, and motivates searches for correlated higher-energy recoil lines in argon. Recoil lines in different isotopes reconstruct a common invisible-particle mass. The emitted scalar can itself be dark matter, making these searches a probe of ordinary matter converting into a dark sector.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.12045",
  "author_total": 3,
  "authors": [
    {
      "name": "Junseok Lee"
    },
    {
      "name": "Fuminobu Takahashi"
    },
    {
      "name": "Yu-Dai Tsai"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/f3z6b5ct4crt8.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.12045",
  "fulltext_url": null,
  "id": "f3z6b5ct4crt8",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.12045",
  "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",
      "hep-ph"
    ],
    [
      "openalex",
      "3106|Dark Matter and Cosmic Phenomena"
    ]
  ],
  "openalex": "W7213086569",
  "pdf_url": "https://arxiv.org/pdf/2609.12045",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-29",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/f3z6b5ct4crt8.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:25:31Z",
      "native_id": "2609.12045",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.12045"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:hep-ph",
      "subfield": "high-energy"
    }
  ],
  "title": "Nuclear Recoils from Invisible Neutron-Pair Annihilation and the LZ event",
  "title_text": "Nuclear Recoils from Invisible Neutron-Pair Annihilation and the LZ event",
  "type": "preprint",
  "updated_at": "2026-10-30T12:25:31Z",
  "url": "https://research.draconitic.com/paper/f3z6b5ct4crt8",
  "venue": "arXiv",
  "versions": []
}