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Friedman","submitted_at":"2019-01-10T12:41:34Z","abstract_excerpt":"Earlier work suggested that the in-medium $\\pi N$ threshold isovector amplitude $b_1(\\rho)$ gets renormalized in pionic atoms by about 30% away from its $\\rho=0$ free-space value, relating such renormalization to the leading low-density decrease of the in-medium quark condensate $<\\bar q q>$ and the pion decay constant $f_{\\pi}$ in terms of the pion-nucleon $\\sigma$ term $\\sigma_{\\pi N}$. Accepting the validity of this approach, we extracted $\\sigma_{\\pi N}$ from a large-scale fit of pionic-atom level shift and width data across the periodic table. Our fitted value $\\sigma_{\\pi N}=57\\pm 7$ MeV"},"verification_status":{"content_addressed":true,"pith_receipt":true,"author_attested":false,"weak_author_claims":0,"strong_author_claims":0,"externally_anchored":false,"storage_verified":false,"citation_signatures":0,"replication_records":0,"graph_snapshot":true,"references_resolved":false,"formal_links_present":false},"canonical_record":{"source":{"id":"1901.03130","kind":"arxiv","version":2},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"nucl-th","submitted_at":"2019-01-10T12:41:34Z","cross_cats_sorted":["hep-ph","nucl-ex"],"title_canon_sha256":"5192b9157310d354782e94af7ca3d6bb23e7bfaafacbec51ef6663e32e12800d","abstract_canon_sha256":"0537f3d5835dcd72f9c13a1f7ed86f27c1750df21685629f0fa623eb9c53acab"},"schema_version":"1.0"},"receipt":{"kind":"pith_receipt","key_id":"pith-v1-2026-05","algorithm":"ed25519","signed_at":"2026-05-17T23:48:50.266520Z","signature_b64":"dtKTbv/n1MthB8hT9iBn2DxAMe8Qp2ciIrHKVvUJ8TzRJ1ddbvvMU7sf9efP5vSRlcomgU9U3fxebE/ko5iaDg==","signed_message":"canonical_sha256_bytes","builder_version":"pith-number-builder-2026-05-17-v1","receipt_version":"0.3","canonical_sha256":"6ce966133bc82212d7d583584282386c49d8b63f1bb1089fc482affdb787e7ff","last_reissued_at":"2026-05-17T23:48:50.265823Z","signature_status":"signed_v1","first_computed_at":"2026-05-17T23:48:50.265823Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"graph_snapshot":{"paper":{"title":"The pion-nucleon $\\sigma$ term from pionic atoms","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["hep-ph","nucl-ex"],"primary_cat":"nucl-th","authors_text":"A. Gal, E. Friedman","submitted_at":"2019-01-10T12:41:34Z","abstract_excerpt":"Earlier work suggested that the in-medium $\\pi N$ threshold isovector amplitude $b_1(\\rho)$ gets renormalized in pionic atoms by about 30% away from its $\\rho=0$ free-space value, relating such renormalization to the leading low-density decrease of the in-medium quark condensate $<\\bar q q>$ and the pion decay constant $f_{\\pi}$ in terms of the pion-nucleon $\\sigma$ term $\\sigma_{\\pi N}$. Accepting the validity of this approach, we extracted $\\sigma_{\\pi N}$ from a large-scale fit of pionic-atom level shift and width data across the periodic table. 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