{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"43c424fc9b656f5ae11bee774c917673dbeb6a4394052d839fbffe17a42ed6fa","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["c33bc4fa1e7ac15424162a61d3c3048525dc366852aac44e27e7317f73b058ae","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"d7e05e15694907227b3c671b26cbcd96d472edb80cbe08a84efc916d7c72f67e","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"hep.grand-unification.neutron-antineutron","kind":"well-posed","literature_status":"open","n":"2","parents":[],"plain":"Some theories allow a neutron to turn into its own antiparticle, changing baryon number by two. This would not show up in proton decay searches.","posed_since":"1970","precise":"Search for $\\Delta B = 2$ neutron-antineutron oscillations with free-neutron oscillation time $\\tau_{\\mathrm{nnbar}} > 8.6 \\times 10^{7}\\,\\mathrm{s}$ (ILL, 1994) and bound-neutron limits converting to $\\sim 4.7 \\times 10^{8}\\,\\mathrm{s}$ (Super-Kamiokande, 2021). An answer is a detection or a free-neutron limit improved by 1 to 3 orders of magnitude.","problem_ref":"c33bc4fa1e7ac15424162a61d3c3048525dc366852aac44e27e7317f73b058ae","references":"","settled_by":"The proposed NNBAR experiment at the European Spallation Source and bound-neutron searches in DUNE and Hyper-Kamiokande.","status_note":"","title":"Do neutrons oscillate into antineutrons?","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"d9134f2bc7150e8450c4b9c3d98cb5c05ff2d160f7ae79abd3ab70d298f7fd85","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"37017e09c28e0fe4143e44fea5b1ff4c5fff969d8e50018da60ff07ad606393e","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"TTxlKxi1CtpinmV-QEN-xtjXb7CHZHQ1d-YT7srD7gu9K3HDJIWVjXYtMvS0hxcaUQ10uMu315h3wjFXNa_sCw"},"schema":"pubphys.envelope/1"},"record_hash":"d9134f2bc7150e8450c4b9c3d98cb5c05ff2d160f7ae79abd3ab70d298f7fd85","leaf_index":3346}