{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"effa24e1d2c3aa8a57917d9b0bdfc9b8370602c41e9a86aae4010d19c06c027b","created":"2026-10-03T07:17:53Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"6a39bb4afb114f875e76a30e2e4538ade676c93631faec4894afd9a656dd9cbd","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"amo.lorentz-cpt.antihydrogen-hyperfine","kind":"well-posed","literature_status":"open","n":"1","parents":[],"plain":"The tiny splitting caused by the magnetic interaction of the antiproton and positron is sensitive to different possible symmetry violations than the optical line. It has been measured only to a few parts in 10000.","posed_since":"","precise":"Measure the zero-field ground-state hyperfine splitting of antihydrogen (hydrogen: 1420.405751768 MHz) with relative uncertainty below 1e-6, using either an in-beam Rabi method (ASACUSA) or trapped-atom microwave spectroscopy (ALPHA), and determine whether it differs from hydrogen.","problem_ref":null,"references":"","settled_by":"A beam or trap measurement of the Hbar hyperfine splitting with ppm uncertainty compared to the hydrogen maser value.","status_note":"","title":"Antihydrogen ground-state hyperfine splitting at the ppm level","topic_ref":"a6fc573c8db5bce913b8300d4956b1137cedf47b39c553b8063ed7baf3f179b3"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"d72b7e7b13996f6c75bd300bd2ae8e4575d32e3ca688b0ba9d6d5c144bb5364e","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"c89f2472ac9318acf15beb696020192963840c050454cf1ab520035d3f2b0228","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"LGPnAuU1cyX5Um2fsKux6zaM_CqkCCyR-0fnkn8aWIaknBjOWntOBgbUWFGJ5r22lqIDsp-YakVHuExEVsm9BA"},"schema":"pubphys.envelope/1"},"record_hash":"d72b7e7b13996f6c75bd300bd2ae8e4575d32e3ca688b0ba9d6d5c144bb5364e","leaf_index":419}