{
  "annotation_id": "e5e647ac-c9ef-4e43-91f8-fb1d244e45f3",
  "date_created": "2026-03-02T18:00:21.972000Z",
  "date_modified": "2026-03-02T18:00:21.972000Z",
  "file_hash": "fad08eecc0f04c1f0067532d0dc12f612f343d30ab5656a48d8a15120666c897",
  "private": false,
  "record": {
    "abstract": "For nearly fifty years theoretical and experimental efforts in\nnucleon-nucleon bremsstrahlung (NN$\\gamma$) have been devoted to measuring\noff-shell amplitudes and distinguishing among various NN potentials on the\nbasis of their off-shell behavior. New experiments are underway, designed\nspecifically to attain kinematics further off shell than in the past, and thus\nto be more sensitive to the off-shell behavior. This letter shows that,\ncontrary to these expectations, and due to the invariance of the S-matrix under\ntransformations of the fields, the off-shell NN amplitude is as a matter of\nprinciple an unmeasurable quantity in NN$\\gamma$.",
    "arxiv_id": "nucl-th/9710061",
    "authors": [
      "Harold W. Fearing"
    ],
    "categories": [
      "nucl-th",
      "hep-ph"
    ],
    "doi": "10.1103/PhysRevLett.81.758",
    "journal_ref": "Phys. Rev. Lett. 81 (1998) 758",
    "title": "Nucleon-nucleon bremsstrahlung: An example of the impossibility of   measuring off-shell amplitudes",
    "url": "https://arxiv.org/abs/nucl-th/9710061"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "67b99b44-9b4c-4a7b-b3c3-15418a8f0196",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}