{
  "kind": "published-limit-summary",
  "source_version": "1803.10890v1",
  "source_url": "https://arxiv.org/pdf/1803.10890v1",
  "citation": "X. Sun et al. (UCNA Collaboration, 2018), Search for dark matter decay of the free neutron from the UCNA experiment: n → χ + e+e−, Physical Review C 97, 052501(R). DOI: 10.1103/PhysRevC.97.052501. Numerical version: arXiv:1803.10890v1.",
  "channel": "n-to-chi-electron-positron",
  "observable": "summed-pair-kinetic-energy",
  "energy_unit": "keV",
  "lower_exclusive": 100,
  "upper_exclusive": 644,
  "branch_ceiling": 0.0001,
  "branch_ceiling_as_printed": "< 10^-4",
  "branch_unit": "fraction-of-all-neutron-decays",
  "limit_relation": "less-than",
  "confidence_relation": "greater-than",
  "confidence": 0.9,
  "acceptance_model": "UCNA-uniform-three-body-phase-space",
  "signal_shape": "single-nearly-monoenergetic-pair-sum",
  "published_dominant_sigma": "≫5σ",
  "published_dominant_branch": 0.01,
  "simulated_signal_keV": [
    322,
    644
  ],
  "source_locations": [
    "Abstract",
    "Physical PDF page 4: uniform phase space acceptance",
    "Physical PDF page 4: Figure 4 legend, simulated signals at 322 keV and 644 keV",
    "Physical PDF page 5: Figure 5 and accompanying text"
  ],
  "available_inputs": [
    "published-limit-summary"
  ],
  "missing_inputs": [
    "foreground counts",
    "background counts",
    "detector response",
    "analysis-ready likelihood"
  ],
  "licence": "Independently transcribed numerical facts only. Article copyright 2018 American Physical Society. No article, figure or event data redistributed; no underlying article reuse rights granted.",
  "licence_url": "https://journals.aps.org/prc/abstract/10.1103/PhysRevC.97.052501",
  "retrieved": "2026-09-22"
}