{
  "abstract": "We prove that, as the lattice spacing $h$ tends to zero, general solutions to the infinite Fermi--Pasta--Ulam--Tsingou (FPUT) system can be approximated in $L^2$ by two counter-propagating Korteweg--de Vries (KdV) waves on time intervals of order $\\log(1/h)$. This resolves an open question raised by the first author and collaborators~\\cite{HKY2021}. Our proof combines the FPUT conservation law with an $h$-uniform local well-posedness theory in $L^2$ and persistence of Sobolev regularity. We also introduce a frequency-localized auxiliary equation to overcome the difficulty of comparing the Fourier restriction norms associated with the FPUT and KdV flows.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.30668",
  "author_total": 2,
  "authors": [
    {
      "name": "Younghun Hong"
    },
    {
      "name": "Junyeong Jang"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7bdcznkg8rs3a.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.30668",
  "fulltext_url": null,
  "id": "7bdcznkg8rs3a",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.30668",
  "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",
      "math.AP"
    ],
    [
      "openalex",
      "2610|Advanced Mathematical Physics Problems"
    ]
  ],
  "openalex": "W7214595956",
  "pdf_url": "https://arxiv.org/pdf/2609.30668",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-01",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/7bdcznkg8rs3a.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:26:07Z",
      "native_id": "2609.30668",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.30668"
    }
  ],
  "subjects": [
    {
      "field": "mathematics",
      "origin": "arxiv:math.AP",
      "subfield": "analysis-pdes"
    }
  ],
  "title": "Long-time Korteweg-de Vries approximation for the Fermi-Pasta-Ulam-Tsingou system",
  "title_text": "Long-time Korteweg-de Vries approximation for the Fermi-Pasta-Ulam-Tsingou system",
  "type": "preprint",
  "updated_at": "2026-10-30T12:26:07Z",
  "url": "https://research.draconitic.com/paper/7bdcznkg8rs3a",
  "venue": "arXiv",
  "versions": []
}