{"paper":{"title":"Improved empirical parametrizations of the $\\gamma^\\ast N \\to \\Delta(1232)$ and $\\gamma^\\ast N \\to N(1520)$ helicity amplitudes and the Siegert's theorem","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["hep-ex","nucl-ex","nucl-th"],"primary_cat":"hep-ph","authors_text":"G. Ramalho","submitted_at":"2016-02-11T19:18:42Z","abstract_excerpt":"In the nucleon electroexcitation reactions, $\\gamma^\\ast N \\to R$, where $R$ is a nucleon resonance ($N^\\ast$), the electric amplitude $E$, and the longitudinal amplitude $S_{1/2}$, are related by $E \\propto \\frac{\\omega}{|{\\bf q}|}S_{1/2}$, at the pseudo-threshold limit ($|{\\bf q}| \\to 0$), where $\\omega$ and $|{\\bf q}|$ are respectively the energy and the magnitude of three-momentum of the photon. The previous relation is usually refereed as the Siegert's theorem. The form of the electric amplitude, defined in terms of the transverse amplitudes $A_{1/2}$ and $A_{3/2}$, and the explicit coeff"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1602.03832","kind":"arxiv","version":2},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}