{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"a884088251c8d5df22ae7475f4e2f42a9c39a23e5ba8846c8b87318c57862f5c","created":"2026-10-03T07:18:05Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"61bfbd25782be6976ac27345a97b43a65ef8a3ee2e6ed064a6b8493c87ae19a3","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"hep.flavor-anomalies.rd-rdstar","kind":"well-posed","literature_status":"open","n":"1","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 +- 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":null,"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":"67e36a860662b77a3c30ab454eb65cfa879e6c2949ab905ac9b1ccef959fe797"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"cf305a525c882a5577cec815e3dde63561fa25b6afe1fa0aba4d30351b5f49e9","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"da24f00413f361ac34b383ee99372a22ad754b4a5d30e77f34f1a11d9a300399","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"RyociF6dP_ryCNnTQLpq01SaJ8b0XEegpgzECtgEeF3l62ZjKxMcAZLFGAxhSny7eCEPWPGjrXipGSkhPDiRBg"},"schema":"pubphys.envelope/1"},"record_hash":"cf305a525c882a5577cec815e3dde63561fa25b6afe1fa0aba4d30351b5f49e9","leaf_index":1540}