{
  "abstract": "Retarded thermal correlators, analytically continued to complex frequency, exhibit non-hydrodynamic poles and branch cuts that constrain hydrodynamics. We construct Gaussian Schwinger-Keldysh effective actions in which branch cuts arise from continua of relaxation poles and response functions are governed by Stieltjes transforms of relaxation-time densities. Dynamical KMS symmetry, positivity and stability constrain the spectra, while endpoint behaviour controls the local branch structure and near-edge pole scaling. The illustrative examples of uniform and power-law densities exhibit respectively beyond-all-orders pole-endpoint separation and a continuous interpolation between pole-pole and pole-branch-point termination. Finally, we show that an energy-dependent relaxation-time approximation in kinetic theory provides a microscopic realization of our branch cuts at zero momentum.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.16164",
  "author_total": 3,
  "authors": [
    {
      "name": "Andrea Amoretti"
    },
    {
      "name": "Matteo Anselmi"
    },
    {
      "name": "Daniel K. Brattan"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/c2a9jb66pn250.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.16164",
  "fulltext_url": null,
  "id": "c2a9jb66pn250",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.16164",
  "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",
      "cond-mat.stat-mech"
    ],
    [
      "arxiv",
      "hep-th"
    ],
    [
      "openalex",
      "3106|High-Energy Particle Collisions Research"
    ]
  ],
  "openalex": "W7213392539",
  "pdf_url": "https://arxiv.org/pdf/2609.16164",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-24",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/c2a9jb66pn250.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:24:52Z",
      "native_id": "2609.16164",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.16164"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:hep-th",
      "subfield": "high-energy"
    },
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.stat-mech",
      "subfield": "statistical-nonlinear"
    }
  ],
  "title": "Schwinger-Keldysh effective actions for non-hydrodynamic poles and branch cuts",
  "title_text": "Schwinger-Keldysh effective actions for non-hydrodynamic poles and branch cuts",
  "type": "preprint",
  "updated_at": "2026-10-30T12:24:52Z",
  "url": "https://research.draconitic.com/paper/c2a9jb66pn250",
  "venue": "arXiv",
  "versions": []
}