{
  "annotation_id": "4c0dffd8-f935-4ae3-9f80-da718580533b",
  "date_created": "2026-03-02T18:00:21.962000Z",
  "date_modified": "2026-03-02T18:00:21.962000Z",
  "file_hash": "8c7fd32ce7c81938a84119a5ddbb4d362b43ace520a13ce9cad6d12e60b07a35",
  "private": false,
  "record": {
    "abstract": "We have analysed pion photoproduction imposing constraints from fixed t\ndispersion relations and unitarity. Coupled integral equations for the S and P\nwave multipoles were derived from the dispersion relations and solved by the\nmethod of Omnes and Muskhelishvili. The free parameters were determined by a\nfit to the most recent data for \\pi^{+} and \\pi^{0} production on the proton as\nwell as \\pi^{-} production on the neutron, in the energy We have analysed pion\nphotoproduction imposing constraints from fixed t dispersion relations and\nunitarity. Coupled integral equations for the S and P wave multipoles were\nderived from the dispersion relations and solved by the method of Omnes and\nMuskhelishvili. The free parameters were determined by a fit to the most recent\ndata for \\pi^{+} and \\pi^{0} production on the proton as well as \\pi^{-}\nproduction on the neutron, in the energy range 160 MeV \\leq E_{\\gamma} \\leq 420\nMeV. The lack of high precision data on the neutron and of polarization\nobservables leads to some limitations of our results. Especially the multipole\nM_{1-} connected with the Roper resonance P_{11}(1440) cannot be determined to\nthe required precision. Our predictions for the threshold amplitudes are in\ngood agreement with both the data and chiral perturbation theory. In the region\nof the \\Delta(1232) we have determined the ratio of electric quadrupole and\nmagnetic dipole excitation. The position of the resonance pole is obtained in\nexcellent agreement with pion-nucleon scattering, and the complex residues of\nthe multipoles are determined with the speed-plot technique.",
    "arxiv_id": "nucl-th/9709067",
    "authors": [
      "O. Hanstein",
      "D. Drechsel",
      "L. Tiator"
    ],
    "categories": [
      "nucl-th",
      "hep-ph"
    ],
    "doi": "10.1016/S0375-9474(98)00818-5",
    "journal_ref": "Nucl.Phys.A632:561-606,1998",
    "title": "Multipole analysis of pion photoproduction based on fixed t dispersion   relations and unitarity",
    "url": "https://arxiv.org/abs/nucl-th/9709067"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "68522367-7335-4a2a-b7dc-b84336eb3fde",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}