{
  "annotation_id": "4aed0db7-3512-4e69-9e32-a27dbb2554d9",
  "date_created": "2026-03-02T18:00:11.672000Z",
  "date_modified": "2026-03-02T18:00:11.672000Z",
  "file_hash": "ace69f01d3f1d36b0efd4539362d4e63f87a37f4f4d3e7396f594cb4ec085d99",
  "private": false,
  "record": {
    "abstract": "A covariant, unitary and gauge invariant theory for pion photoproduction on a\nsingle nucleon is presented. To achieve gauge invariance at the operator level\none needs to include both the $\\pi N$ and $\\gamma\\pi N$ thresholds. The final\namplitude can be written in terms of a distorted wave in the final $\\pi N$\nchannel provided one includes additional diagrams to the standard Born term in\nwhich the photon is coupled to the final state pion and nucleon. These\nadditional diagrams are required in order to satisfy gauge invariance.",
    "arxiv_id": "nucl-th/9308014",
    "authors": [
      "C. H. M. van Antwerpen",
      "I. R. Afnan"
    ],
    "categories": [
      "nucl-th"
    ],
    "title": "A Gauge Invariant Unitary Theory for Pion Photoproduction",
    "url": "https://arxiv.org/abs/nucl-th/9308014"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "d78a290a-7c70-4f02-8720-215ac88b1dd7",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}