{
  "abstract": "Building on Part I of this series, where we described the emergence of massive scattering states, we demonstrate how unitary lowest-weight representations $\\mathcal D(Δ,s)$ of the conformal group with fixed dimension $Δ$ and arbitrary integer spin $s$ contract to massless Poincaré particle representations. This requires combining the Inönü--Wigner contraction $\\mathfrak{so}(2,3) \\to \\mathfrak{iso}(1,3)$ with an infinite boost, in which case massless scattering states naturally emerge in a carrollian basis. For $Δ>s+1$, we find that $\\mathcal D(Δ,s)$ contracts to the direct sum of massless particles of all spins $s'\\leq s$. At the unitarity bound, lower-spin states become null so that $\\mathcal D(s+1,s)$ contracts to a single massless particle representation carrying the two maximal helicities $J=\\pm s$. In both cases, the inner product converges to the Poincaré-invariant one after a single helicity-independent rescaling, so that unitarity is preserved throughout the contraction.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.40878",
  "author_total": 1,
  "authors": [
    {
      "name": "Kevin Nguyen"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/a631cv5vn5jd7.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.40878",
  "fulltext_url": null,
  "id": "a631cv5vn5jd7",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.40878",
  "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-th"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2610.40878",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-29",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/a631cv5vn5jd7.ris",
  "sources": [
    {
      "first_seen": "2026-11-02T12:21:15Z",
      "native_id": "2610.40878",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.40878"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:hep-th",
      "subfield": "high-energy"
    }
  ],
  "title": "Hilbert space in the flat limit of AdS/CFT. II. Massless particles",
  "title_text": "Hilbert space in the flat limit of AdS/CFT. II. Massless particles",
  "type": "preprint",
  "updated_at": "2026-11-04T15:20:51Z",
  "url": "https://research.draconitic.com/paper/a631cv5vn5jd7",
  "venue": "arXiv",
  "versions": []
}