{"paper":{"title":"Spectral functions of nucleon form factors: Three-pion continua at low energies","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["hep-ph"],"primary_cat":"nucl-th","authors_text":"E. Passemar, N. Kaiser","submitted_at":"2019-01-09T18:34:26Z","abstract_excerpt":"We study the imaginary parts of the isoscalar electromagnetic and isovector axial form factors of the nucleon close to the $3\\pi$-threshold in covariant baryon chiral perturbation theory. At the two-loop level, the contributions arising from leading and next-to-leading order chiral $\\pi N$-vertices, as well as pion-induced excitations of virtual $\\Delta(1232)$-isobars, are calculated. It is found that the heavy baryon treatment overestimates substantially these $3\\pi$-continua. From a phenomenological analysis, that includes the narrow $\\omega(783)$-resonance or the broad $a_1$-resonance, one "},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1901.02865","kind":"arxiv","version":1},"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"}