{
  "abstract": "We investigate thermalization in finite quantum systems with strong long-range interactions. Nearly conserved quantities inherited from the fully connected limit organize the Hilbert space into weakly coupled sectors and split the many-body spectrum into energy bands. Despite the resulting breakdown of global ergodicity, quantum chaos develops within individual energy bands, enabling the definition of microcanonical ensembles within the bands. This supports a band-resolved formulation of thermalization, which we term fragmented eigenstate thermalization hypothesis (fETH). Unlike conventional ETH, finite-size scaling in fETH obeys a symmetry-imposed selection rule that restricts which system sizes can be compared. This band-resolved description has consequences for equilibrium statistical mechanics. While microcanonical ensembles remain confined to a single band, canonical ensembles mix different bands. This mismatch explains ensemble inequivalence without invoking equilibrium phase transitions. Our results apply broadly to Hamiltonians near a fully permutation-symmetric limit.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2607.15350",
  "author_total": 3,
  "authors": [
    {
      "name": "C. L. Sriram"
    },
    {
      "name": "Soumya Kanti Pal"
    },
    {
      "name": "Lea F. Santos"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/0jbznwxrzzmm6.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2607.15350",
  "fulltext_url": null,
  "id": "0jbznwxrzzmm6",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2607.15350",
  "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",
      "cond-mat.stat-mech"
    ],
    [
      "arxiv",
      "quant-ph"
    ],
    [
      "openalex",
      "3107|Quantum many-body systems"
    ]
  ],
  "openalex": "W7169811473",
  "pdf_url": "https://arxiv.org/pdf/2607.15350",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-03",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/0jbznwxrzzmm6.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:19:14Z",
      "native_id": "2607.15350",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2607.15350"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    },
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.stat-mech",
      "subfield": "statistical-nonlinear"
    }
  ],
  "title": "Fragmented ETH and Ensemble Inequivalence",
  "title_text": "Fragmented ETH and Ensemble Inequivalence",
  "type": "preprint",
  "updated_at": "2026-10-30T12:19:14Z",
  "url": "https://research.draconitic.com/paper/0jbznwxrzzmm6",
  "venue": "arXiv",
  "versions": []
}