{
  "annotation_id": "1bfe5c9b-0d8c-4372-b42a-262a2ef95e2e",
  "date_created": "2026-03-02T18:02:34.486000Z",
  "date_modified": "2026-03-02T18:02:34.486000Z",
  "file_hash": "d86a07ded8d429ca618f3593c566169b455a1180a0e147aaf5276c0794a10d7b",
  "private": false,
  "record": {
    "abstract": "The structure of Pais-Uhlenbeck oscillator in the equal-frequency limit has\nbeen recently studied by Mannheim and Davidson [Phys.Rev. A71 (2005), 042110].\nIt appears that taking this limit, as presented in the above paper, is quite\nsubtle and the resulting structure of space of states - involved. In order to\nclarify the situation we present here the proper way of taking the\nequal-frequency limit, first under the assumption that the scalar product in\nthe space of states is positive defined. We discuss also the case of indefinite\nmetric space of states. We show that, irrespective of the way the limit is\ndefined, the limiting theory can be hardly viewed as satisfactory.",
    "arxiv_id": "quant-ph/0612009",
    "authors": [
      "Katarzyna Bolonek",
      "Piotr Kosinski"
    ],
    "categories": [
      "quant-ph"
    ],
    "title": "Comment on \"Dirac Quantization of Pais-Uhlenbeck Fourth Order   Oscillator\"",
    "url": "https://arxiv.org/abs/quant-ph/0612009"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "841d81dc-a8b9-4e94-9b89-96492229dbbe",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}