{
  "abstract": "A bstract : In this work, we build a novel frequency-momentum space for ( d + 1)-dimensional de Sitter (dS) correlators from first principles. This construction follows directly from the decomposition into unitary irreducible representations (UIRs) of the spacetime isometry group SO(1, d + 1). While the spatial momentum space is given by the standard d -dimensional Fourier transform, the frequency space arises from diagonalising the quadratic Casimir operator, leading to the ( d + 1)-dimensional Kontorovich-Lebedev-Fourier (KLF) transform. We show that square-integrable functions decompose only along the principal series, whereas more general functions can receive discrete contributions from other UIRs. Applying this framework to the bulk CFT two-point function reproduces its Källén-Lehmann representation. Using the path integral formulation, we derive the Feynman rules for in-in perturbation theory in KLF space, leading to the introduction of KLF-space correlators, which are simply related to late-time correlation functions through a reduction formula. Furthermore, the KLF-space formulation sheds light on the simple mathematical structure of perturbative computations. In particular, the propagators take the form of simple rational functions, and tree-level diagrams can be written as spectral integrals over known meromorphic functions, as demonstrated in the example of the single-exchange four-point function. At the loop level, we show, through the example of the self-energy correction to the scalar propagator, that the group-theoretical nature of the construction allows the momentum integral to be recast as an orthogonality relation among SO(1, d + 1) Clebsch-Gordan coefficients.",
  "abstract_shown": true,
  "affiliations": [
    "Sorbonne Université",
    "Max-Planck-Institut für Physik (Werner-Heisenberg-Institut)",
    "Max Planck-IAS-NTU Center for Particle Physics, Cosmology and Geometry"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 4,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Nathan Belrhali",
      "orcid": "0009-0005-2279-9006"
    },
    {
      "affs": [
        0
      ],
      "name": "Arthur Poisson",
      "orcid": "0009-0008-9288-649X"
    },
    {
      "affs": [
        0
      ],
      "name": "Sébastien Renaux-Petel",
      "orcid": "0000-0001-9730-4032"
    },
    {
      "affs": [
        0,
        1,
        2
      ],
      "name": "Denis Werth",
      "orcid": "0000-0002-3431-8186"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/d573qq95f266n.bib",
  "cited_by": 0,
  "doi": "10.1007/jhep10(2026)242",
  "fulltext_url": null,
  "id": "d573qq95f266n",
  "issns": [
    "1029-8479"
  ],
  "landing_url": "https://link.springer.com/article/10.1007/JHEP10(2026)242",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "3106|Black Holes and Theoretical Physics"
    ]
  ],
  "openalex": "W7154725884",
  "pdf_url": "https://link.springer.com/content/pdf/10.1007/JHEP10(2026)242.pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-23",
  "publisher": "Springer Science and Business Media LLC",
  "ris": "https://research.draconitic.com/paper/d573qq95f266n.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:01Z",
      "native_id": "10.1007/jhep10(2026)242",
      "source": "crossref",
      "url": "https://link.springer.com/article/10.1007/JHEP10(2026)242"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "openalex:3106|Black Holes and Theoretical Physics",
      "subfield": "high-energy"
    }
  ],
  "title": "Kontorovich-Lebedev-Fourier space for de Sitter correlators",
  "title_text": "Kontorovich-Lebedev-Fourier space for de Sitter correlators",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:18:01Z",
  "url": "https://research.draconitic.com/paper/d573qq95f266n",
  "venue": "Journal of High Energy Physics",
  "versions": []
}