{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"1aad0e6ed6bd21fff5568a17f0b7abc734342e4175780b0c031fa52b77f7a265","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b","f9794321318da5a15c677d4d95fcca9b9be6737584554573c57eaed87bfb4769"],"salt":"ff16a2b5b9791540b397275197de5b0b5381df11d3bd0d60e16c5b9acebf1ae6","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"hep.neutrino-mass.majorana-or-dirac","kind":"well-posed","literature_status":"open","n":"2","parents":[],"plain":"If a neutrino is its own antiparticle, certain nuclei could undergo a double beta decay that emits no neutrinos at all. Its observation would show that lepton number is not conserved.","posed_since":"1937","precise":"Determine whether lepton number is violated by Majorana neutrino masses via neutrinoless double beta decay, with half-life T_1/2 $\\sim 10^{26}$ to $10^{28}$ yr for $m_{bb} \\sim 10\\ \\text{to}\\ 50\\ \\mathrm{meV}$. KamLAND-Zen (2024) gives T_1/2(Xe-136) > $3.8 \\times 10^{26}$ yr, $m_{bb} < \\sim 28\\ \\text{to}\\ 122\\ \\mathrm{meV}$ (spread from nuclear matrix elements).","problem_ref":"f9794321318da5a15c677d4d95fcca9b9be6737584554573c57eaed87bfb4769","references":"","settled_by":"Ton-scale double beta decay experiments (LEGEND-1000, nEXO, CUPID, KamLAND2-Zen) covering the inverted-ordering band $m_{bb} \\sim 15\\text{ to }50\\,\\mathrm{meV}$.","status_note":"No signal through 2025; the inverted-ordering band is partly probed.","title":"Are neutrinos Majorana particles, their own antiparticles?","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"45e57c29f38fcc375e4eb4ed9fca5ad5c83c6080b1f4e66d21833dfceb233a4d","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"a121e533025a550d61d656fe89e40785d07368365fdf5b1148fae42c257d2c85","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"7pSxT3y1M6YTb5HgegikbGaoMTrzNlu5boDjacZaJwpuaPXdCjIqZ0vR6hjpJkq6Gnb60jAt_F2hEZYw0bXLDA"},"schema":"pubphys.envelope/1"},"record_hash":"45e57c29f38fcc375e4eb4ed9fca5ad5c83c6080b1f4e66d21833dfceb233a4d","leaf_index":3376}