{"paper":{"title":"Two-photon-exchange effects in the electro-excitation of the $\\Delta$ resonance","license":"","headline":"","cross_cats":[],"primary_cat":"hep-ph","authors_text":"Carl E. Carlson, JLAB), Marc Vanderhaeghen (William-Mary College, Vladimir Pascalutsa","submitted_at":"2005-09-06T23:59:53Z","abstract_excerpt":"We evaluate the two-photon exchange contribution to the $e N \\to e \\Delta(1232) \\to e \\pi N$ process at large momentum transfer with the aim of a precision study of the ratios of electric quadrupole (E2) and Coulomb quadrupole (C2) to the magnetic dipole (M1) $\\gamma^* N \\Delta$ transitions. We relate the two-photon exchange amplitude to the $N \\to \\Delta$ generalized parton distributions and obtain a quantitative estimate of the two-photon effects. The two-photon exchange corrections to the C2/M1 ratio depend strongly on whether this quantity is obtained from an interference cross section or "},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"hep-ph/0509055","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"}