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We advocate a new strategy for utilizing pion beta decay, based on its role in determining ${V_{\\text{us}} / V_{\\text{ud}}}$ via the ratio $R_V=\\Gamma\\left(K\\to \\pi l \\nu(\\gamma)\\right)/\\Gamma\\left(\\pi^+\\to \\pi^0 e^+\\nu(\\gamma)\\right)$. $R_V$ measures $ { f_+^K(0) |V_{\\text{us}}| / f_+^\\pi(0) |V_{\\text{ud}}| }$ and is insensiti"},"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":"1911.04685","kind":"arxiv","version":2},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"hep-ph","submitted_at":"2019-11-12T05:42:45Z","cross_cats_sorted":["hep-ex","hep-lat","nucl-th"],"title_canon_sha256":"f2a2bbb70ce1d3994724e3ef5800e3f3aee94248a251a784e5b444bac5d2de07","abstract_canon_sha256":"d5bcecc62da7ff94f15dba1e884d031d61de45a6e3d9334cc06f712dbd433a6d"},"schema_version":"1.0"},"receipt":{"kind":"pith_receipt","key_id":"pith-v1-2026-05","algorithm":"ed25519","signed_at":"2026-07-05T01:06:19.166921Z","signature_b64":"KLX2VhJgOP0zuBRVxUmYm7eXGVD6H2lkM07+jADrEEfDDNwUmh/FDP8pjY/gtU9FsmGhSfJkmZtCe9uO8DQBBw==","signed_message":"canonical_sha256_bytes","builder_version":"pith-number-builder-2026-05-17-v1","receipt_version":"0.3","canonical_sha256":"da5d39da1cb5e5f3d1b49d0291a5dcbd45ae7c3ba9d7392e45c42990ead1c678","last_reissued_at":"2026-07-05T01:06:19.166483Z","signature_status":"signed_v1","first_computed_at":"2026-07-05T01:06:19.166483Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"graph_snapshot":{"paper":{"title":"Pion Beta Decay and CKM Unitarity","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["hep-ex","hep-lat","nucl-th"],"primary_cat":"hep-ph","authors_text":"Alberto Sirlin, Andrzej Czarnecki, William J. 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