{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"8b2e8bfaded3546c81f2c8e7976df49df2b9c460f2b52f847a2e7de2d8641b0d","created":"2026-10-03T07:18:05Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"8585c18d5750c651d3b6950743f233fb4dfc08ce13ef80926456b8de840bcdff","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"hep.neutrino-mass.absolute-mass","kind":"well-posed","literature_status":"open","n":"1","parents":[],"plain":"Oscillations measure only differences of neutrino masses. The overall scale must come from precise $\\beta$ decay spectra or from how neutrinos affected the growth of cosmic structure.","posed_since":"","precise":"Determine $m_{\\mathrm{lightest}}$, or equivalently $m_{\\beta}=(\\operatorname{sum}\\left|U_{ei}\\right|^{2}m_i^{2})^{1/2}$ and $\\operatorname{sum} m_{\\nu}$. KATRIN (2025) gives $m_{\\beta}<0.45\\ \\mathrm{eV}$ (90 percent CL); oscillations require $\\operatorname{sum} m_{\\nu}\\ge \\sim 0.059\\ \\mathrm{eV}$ (normal) or $\\sim 0.10\\ \\mathrm{eV}$ (inverted). An answer is a nonzero value with $\\sim 20\\ \\mathrm{percent}$ uncertainty or a consistent upper limit across laboratory and cosmology.","problem_ref":null,"references":"","settled_by":"Cosmological detection of sum $m_{\\nu}$ at $\\ge 3\\sigma$ (DESI, Euclid, CMB-S4) cross-checked by a laboratory direct measurement (Project 8 or successors) reaching $m_{\\beta} \\sim 40\\,\\mathrm{meV}$.","status_note":"DESI DR2 plus CMB (2025) gives sum $m_{\\nu} < 0.064\\,\\mathrm{eV}$ (95 percent, LCDM), in tension with the oscillation minimum; the tension relaxes in evolving dark energy fits.","title":"What is the mass of the lightest neutrino?","topic_ref":"bf623edd63337963e5d02d169573ea3befbc30edcb8ee813200a0e5d35d5421d"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"02ea08734e6f7503d0222ff513d71aa481eb674b5da50e563ee8a8a626fb168a","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"baac5fb030ab0379879b3c5af961731a07b08e5f4fa273ce112bc249326e41a8","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"-7WIjeG3nRVDecOVL2WE3RxdBEQ-EJAUhOANzRSWvqqjAy-G2sYFKqgJzBOm5GJ-PCBfhKOqcmXLpJQ6SXUUAA"},"schema":"pubphys.envelope/1"},"record_hash":"02ea08734e6f7503d0222ff513d71aa481eb674b5da50e563ee8a8a626fb168a","leaf_index":1570}