{"paper":{"title":"Neutral pion photoproduction on the nucleon in a chiral quark model","license":"http://creativecommons.org/licenses/by/4.0/","headline":"","cross_cats":["hep-ex","hep-ph","nucl-ex"],"primary_cat":"nucl-th","authors_text":"Li-Ye Xiao, Xian-Hui Zhong, Xu Cao","submitted_at":"2015-05-24T02:45:11Z","abstract_excerpt":"A chiral quark-model approach is adopted to study the $\\gamma p\\rightarrow \\pi^0p$ and $\\gamma n\\rightarrow \\pi^0 n$ reactions. Good descriptions of the total and differential cross sections and single-polarization observables are obtained from the pion production threshold up to the second resonance region. It is found that (i) the $n=0$ shell resonance $\\Delta(1232)P_{33}$, the $n=1$ shell resonances $N(1535)S_{11}$ and $N(1520)D_{13}$, and the $n=2$ shell resonance $N(1720)P_{13}$ play crucial roles in these two processes. They are responsible for the first, second and third bump structures"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1505.06396","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"}