{
  "abstract": "We present a novel method to analyze coherent elastic neutrino--nucleus scattering (CE$ν$NS) data to extract the reactor antineutrino spectrum below the inverse beta decay threshold of 1.8 MeV, where it remains unmeasured. Adapting halo-independent analysis techniques developed for direct dark matter detection, we show how to obtain a best-fit and a pointwise confidence band for the integrated neutrino flux, without assuming a parametric form or smoothness prior for the spectrum. In our approach, which follows from convex geometry arguments, the differential neutrino rate is written as a linear combination of Dirac delta functions -- a finite Dirac sum (FDS) -- with a maximum number of terms determined by the number of data points. We apply our \"FDS method\" to mock CE$ν$NS data for a low-threshold Ge detector and compare it with Tikhonov-regularized unfolding.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2608.16107",
  "author_total": 4,
  "authors": [
    {
      "name": "Muping Chen"
    },
    {
      "name": "Graciela Gelmini"
    },
    {
      "name": "Danny Marfatia"
    },
    {
      "name": "Koichiro Yasuda"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/18p5qfsmx08cb.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2608.16107",
  "fulltext_url": null,
  "id": "18p5qfsmx08cb",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2608.16107",
  "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-ex"
    ],
    [
      "arxiv",
      "hep-ph"
    ],
    [
      "arxiv",
      "nucl-ex"
    ],
    [
      "arxiv",
      "nucl-th"
    ],
    [
      "openalex",
      "3106|Neutrino Physics Research"
    ]
  ],
  "openalex": "W7203716943",
  "pdf_url": "https://arxiv.org/pdf/2608.16107",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-20",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/18p5qfsmx08cb.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:35:15Z",
      "native_id": "2608.16107",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2608.16107"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:hep-ex",
      "subfield": "high-energy"
    },
    {
      "field": "physics",
      "origin": "arxiv:nucl-ex",
      "subfield": "nuclear"
    }
  ],
  "title": "Unfolding the low-energy reactor neutrino flux from CE$ν$NS data with a finite Dirac sum",
  "title_text": "Unfolding the low-energy reactor neutrino flux from CEνNS data with a finite Dirac sum",
  "type": "preprint",
  "updated_at": "2026-10-30T12:35:15Z",
  "url": "https://research.draconitic.com/paper/18p5qfsmx08cb",
  "venue": "arXiv",
  "versions": []
}