{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"03cd9a4dfe8d27b9f62003f0e18fb601e47ddc125a3222a11d1cb6e129c74b0e","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":["ai:gpt-5.5"],"kind":"seed"},"parents":["ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b","cf305a525c882a5577cec815e3dde63561fa25b6afe1fa0aba4d30351b5f49e9"],"salt":"0f35f8fbcc0999bd2b1b83c8658ed6bb679fe6763cb942f314fe5ce9350b6daf","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":["ai:gpt-5.5"],"external_id":"hep.flavor-anomalies.rd-rdstar","kind":"well-posed","literature_status":"open","n":"2","parents":[],"plain":"The SM treats electrons, muons and taus alike except for mass. B meson decays to $\\tau$ leptons occur more often than predicted, by more than 3 standard deviations.","posed_since":"2012","precise":"Determine whether $R(D)=\\operatorname{BR}(B \\to D \\tau \\nu)/\\operatorname{BR}(B \\to D \\ell \\nu)$ and $R(D*)$ exceed the SM values (HFLAV arithmetic average of predictions $0.296 \\pm 0.004\\ \\text{and}\\ 0.254 \\pm 0.005$). The HFLAV ICHEP 2026 averages are $R(D)=0.359 \\pm 0.024$ and $R(D*) = 0.280 \\pm 0.011$ (correlation -0.37), about $3.7\\,\\sigma$ above the SM combined; an answer is $\\ge 5\\,\\sigma$ confirmation or reduction below $2\\,\\sigma$.","problem_ref":"cf305a525c882a5577cec815e3dde63561fa25b6afe1fa0aba4d30351b5f49e9","references":"","settled_by":"Belle II with several $\\mathrm{ab}^{-1}$ and LHCb Run 3 measurements using hadronic and leptonic $\\tau$ decays, with lattice form factors for $B \\to D*$.","status_note":"The HFLAV average updated for ICHEP 2026 (August 2026, including a new Belle II $R(D*)$ result) gives about $3.7\\sigma$.","title":"Is lepton flavor universality violated in $b\\,\\mathrm{to}\\,c\\,\\tau\\,\\nu$ decays?","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"58c9209ae5f89527fd0060fed41161ef09f73e40a3710d43f4343e2093006d5f","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"411a3a0152b54c7e175228ef7c80a327d6615305f457ae2d529507a8c5b44190","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"z17aS-83onk6fXtiDobUAgbLeAaeI_xZQYYzNsIugecwQtYV0fJ2iban-KTSangmR8Yt7-XXLWUvrjl26OvTCw"},"schema":"pubphys.envelope/1"},"record_hash":"58c9209ae5f89527fd0060fed41161ef09f73e40a3710d43f4343e2093006d5f","leaf_index":3338}