{
  "abstract": "We present part one of an SU(3)-flavour-symmetric lattice QCD calculation of the amplitude for a $D$-meson decaying to a $Kπ$ final state in the 27-dimensional irreducible representation of the flavour symmetry group, denoted $(Kπ)_{\\mathbf{27}}$. The Wilson--clover gauge ensembles used in this work, generated by the OpenLat collaboration, are tuned such that $M_π= M_K \\approx 410\\,\\mathrm{MeV}$. Using the distillation framework, we construct a matrix of Euclidean correlation functions from pairs of single-hadron operators projected to definite spatial momentum. Solving a generalised eigenvalue problem yields the finite-volume energy spectrum that is used to determine the scattering phase shift from threshold up to $4 M_π\\approx 1640 \\,\\mathrm{MeV}$, which sits below but plausibly within reach of $M_D^{\\rm SU(3)} \\simeq 1900\\,\\mathrm{MeV}$. The calculation is performed across three lattice spacings, and we apply two strategies in which the continuum limit is taken at different stages of the computation: (i) on the extracted scattering parameters and (ii) on the finite-volume energies at fixed physical volume before extracting the scattering parameters. We find consistent results across these methods for the scattering phase shift as a function of the centre-of-mass energy, $δ_{\\mathbf{27}}(E_{\\sf cm})$. Taking a scattering-length-only parametrisation, we infer a value for the strong phase of the weak decay, $δ_{\\mathbf{27}}(M_D^{\\rm SU(3)})=-38.4(2.4)^\\circ$. We further describe the methodology for using the same operator basis to compute three-point correlation functions to extract $\\langle (Kπ)_{\\mathbf{27}}| H_W| D\\rangle$, for the tree-level effective weak Hamiltonian $H_W$, and for relating such finite-volume matrix elements to the full decay amplitude. The complete analysis leading to the latter will be presented in a forthcoming manuscript.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2608.30737",
  "author_total": 8,
  "authors": [
    {
      "name": "Matthew Black"
    },
    {
      "name": "Felix Erben"
    },
    {
      "name": "Maxwell T. Hansen"
    },
    {
      "name": "Fabian Joswig"
    },
    {
      "name": "Nelson Pitanga Lachini"
    },
    {
      "name": "Rajnandini Mukherjee"
    },
    {
      "name": "Srijit Paul"
    },
    {
      "name": "Antonin Portelli"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/3sr4mzakktqps.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2608.30737",
  "fulltext_url": null,
  "id": "3sr4mzakktqps",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2608.30737",
  "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-lat"
    ],
    [
      "arxiv",
      "hep-ph"
    ],
    [
      "openalex",
      "3106|Quantum Chromodynamics and Particle Interactions"
    ]
  ],
  "openalex": "W7204894709",
  "pdf_url": "https://arxiv.org/pdf/2608.30737",
  "pmcid": null,
  "pmid": null,
  "published": "2026-08-31",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/3sr4mzakktqps.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:41Z",
      "native_id": "2608.30737",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2608.30737"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:hep-lat",
      "subfield": "high-energy"
    }
  ],
  "title": "$D \\to (K π)_{\\mathbf{27}}$ at the SU(3)-flavour-symmetric point I: Methodology and strong phase determination",
  "title_text": "D → (K π)_27 at the SU(3)-flavour-symmetric point I: Methodology and strong phase determination",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:41Z",
  "url": "https://research.draconitic.com/paper/3sr4mzakktqps",
  "venue": "arXiv",
  "versions": []
}