{"paper":{"title":"Nucleon spin structure from the instanton vacuum","license":"","headline":"","cross_cats":[],"primary_cat":"hep-ph","authors_text":"C. Weiss","submitted_at":"1996-04-15T20:30:04Z","abstract_excerpt":"We discuss the evaluation of the nucleon isoscalar axial coupling, $g_A^{(0)}$, in the instanton vacuum, using the $1/N_c$ expansion. This approach allows a fully consistent treatment of the $U(1)_A$ anomaly. We compute the nucleon matrix element of the topological charge density, $\\langle N | F\\widetilde{F} | N \\rangle$, and show that it reduces to the matrix element of the divergence of the isoscalar axial quark current. Our arguments show that the usual evaluation of $g_A^{(0)}$ in the chiral quark soliton model is consistent with the $U(1)_A$ anomaly in leading order of $1/N_c$. Such calcu"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"hep-ph/9604324","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"}