{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"4c08f4eb56cf3a916fe6e1b1c05f45f966713f0ebf9dd1de597866582c316e20","created":"2026-10-03T07:18:05Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"3f757ac51dbff1d2594f9e39d6d795f1e1b6c0f80e699480cdfd27c3bfcb6c5c","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"hep.flavor-puzzle.yukawa-hierarchy","kind":"phenomenon","literature_status":"open","n":"1","parents":[],"plain":"The top quark is about 340000 times heavier than the electron, and quark mixing is small while neutrino mixing is large. No theory predicts these numbers.","posed_since":"","precise":"The SM Yukawa couplings span $y_e \\sim 3e-6$ to $y_t \\sim 1$, CKM angles are small ($\\theta_C \\sim 0.23$, |V_ub| ~ 4e-3) while PMNS angles are large ($\\theta_{12} \\sim 34\\,\\mathrm{deg}$, $\\theta_{23} \\sim 45\\,\\mathrm{deg}$). An answer is a mechanism (Froggatt-Nielsen charges, modular or discrete flavor symmetries, extra-dimensional localization, partial compositeness) that predicts these values with fewer parameters than it explains.","problem_ref":null,"references":"","settled_by":"A model with fewer free parameters than observables whose extra predictions (mixing sum rules, flavor-violating rates, new states) are confirmed.","status_note":"","title":"What determines the hierarchy of quark and lepton masses?","topic_ref":"bf83146b3162b33e3e47622ed38c05336b0c5694b551ceeb82b1dcacaf745590"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"99f833884d96384393205516c986a9ec5e2f8d4df855ee94dca113be77b49833","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"b84d1f683527639f79525d4c2880a8484a9055a433b1f4a1d8c4028df2ea1783","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"m4ijtYsh-xKtEVwGBbR478xjlrCYR6TJ8OIzWEXbWrlBf5r240XtdK8rCUQp5uXOhltY56hTSgI7nld2EABFCw"},"schema":"pubphys.envelope/1"},"record_hash":"99f833884d96384393205516c986a9ec5e2f8d4df855ee94dca113be77b49833","leaf_index":1543}