{
  "abstract": "Baryon-meson sum rules enable cross-checks among exclusive mesonic and baryonic measurements. Unlike their heavy-to-heavy counterparts, analogous heavy-to-light relations lack an explicit heavy-quark-symmetry origin. We investigate their origin in the $b\\to sν\\barν$ system by studying the relevant helicity amplitudes at the two kinematic endpoints. Although the sum rule follows algebraically from the simple short-distance structure, its coefficient depends nontrivially on the hadronic dynamics. At maximum recoil, the coefficient for the daughter baryons ${\\cal B}=Λ,Ξ$ is consistent with the approximate value $1/2$ within current form-factor uncertainties. At zero recoil, by contrast, a kinematic helicity projection enforces its exact vanishing. The fully integrated coefficients are numerically close to $1/4$. However, unlike the one-quarter coefficient in the heavy-to-heavy system, they are not local symmetry coefficients but integrated quantities shaped by the behavior between the two endpoints. This understanding may guide the construction of baryon-meson sum rules in more general heavy-to-light decays.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.21253",
  "author_total": 1,
  "authors": [
    {
      "name": "Syuhei Iguro"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/ek5x3axm4bxrp.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.21253",
  "fulltext_url": null,
  "id": "ek5x3axm4bxrp",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.21253",
  "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-ex"
    ],
    [
      "arxiv",
      "hep-ph"
    ],
    [
      "openalex",
      "3106|Particle physics theoretical and experimental studies"
    ]
  ],
  "openalex": "W7213914848",
  "pdf_url": "https://arxiv.org/pdf/2609.21253",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-18",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/ek5x3axm4bxrp.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:23:03Z",
      "native_id": "2609.21253",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.21253"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:hep-ex",
      "subfield": "high-energy"
    }
  ],
  "title": "Endpoint anatomy of the baryon--meson sum rule in $b\\to sν\\barν$",
  "title_text": "Endpoint anatomy of the baryon--meson sum rule in b→ sνν̅",
  "type": "preprint",
  "updated_at": "2026-10-30T12:23:03Z",
  "url": "https://research.draconitic.com/paper/ek5x3axm4bxrp",
  "venue": "arXiv",
  "versions": []
}