{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"52b1fd4acbbaedeb3026e52b10529a6f859858659eab65f629f86db55b654cb1","created":"2026-10-03T07:17:53Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"896467340862a1a4aec02353ef37dfd9c5bd6e4f06353d7b7277706d822465a2","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"amo.electric-dipole-moments.neutron-edm","kind":"well-posed","literature_status":"open","n":"1","parents":[],"plain":"Slow neutrons stored in a bottle precess in electric and magnetic fields, and a dipole would shift their precession rate when the electric field is flipped. No shift has yet been seen.","posed_since":"1950","precise":"The best bound is $\\left|d_n\\right| < 1.8e-26\\,e\\,\\mathrm{cm}$ (90% CL, PSI 2020) using ultracold neutrons with a Hg-199 comagnetometer. Determine whether $d_n$ is nonzero at the $1e-27\\,e\\,\\mathrm{cm}$ level, which corresponds to the QCD vacuum angle $\\left|\\theta_{\\mathrm{bar}}\\right|$ of order 1e-11 (using $d_n$ of about $1e-16\\,\\theta_{\\mathrm{bar}}\\,e\\,\\mathrm{cm}$).","problem_ref":null,"references":"","settled_by":"A neutron EDM measurement with total uncertainty near 1e-27 e cm (n2EDM at PSI, or the US and Canadian ultracold-neutron efforts).","status_note":"The n2EDM apparatus at PSI was commissioned in 2024-2026 with its magnetic shielding and field uniformity characterized; no new limit as of mid-2026.","title":"Is the neutron EDM nonzero at the 1e-27 e cm level?","topic_ref":"c246b9f50df025b5d8ac429d18d9f7456b8697e6ae051e6f2f11e3e2464e02b9"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"4e501e591b80de7223db2d6ac0131568689664792eb00caa32cd9b7d340fc340","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"3b8f72b7241df8f81d33bca008376b6e11c581089bcc707858888b6acdae3738","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"nJOU_O6HWEd8xtTCLuQ8q8Jmtezb0s7EiHliUil38n4VS9YU935sGqPso_6BpsQMyJavx0qiOOWUvVCeKMA8DA"},"schema":"pubphys.envelope/1"},"record_hash":"4e501e591b80de7223db2d6ac0131568689664792eb00caa32cd9b7d340fc340","leaf_index":407}