{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"d35934032801e54469b1b3c59ced41d87bb2e1a5e84baad9bf0e5531101d3020","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b","d72b7e7b13996f6c75bd300bd2ae8e4575d32e3ca688b0ba9d6d5c144bb5364e"],"salt":"97f2a8d078b91c619a7c5ce06cf001d54801527d8766f043badc1c73eaccf5b3","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":"2","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 $10^{-6}$, using either an in-beam Rabi method (ASACUSA) or trapped-atom microwave spectroscopy (ALPHA), and determine whether it differs from hydrogen.","problem_ref":"d72b7e7b13996f6c75bd300bd2ae8e4575d32e3ca688b0ba9d6d5c144bb5364e","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":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"98c6a017fef356c21d6d6e49c16114be54d16dbca85640a1ebb22dfdcae2694b","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"fb4159dc6d5277e2672aa9458b11750ba21c46670785f3bcb42a0ade3ec58906","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"06zRhQ-Lc7bVY1T04J38o3COCOdfYICvCzpCdjnIJrWJ8lcxJ0ke1TUZLV3Ao4F2ed-CJwCKgqQeaoUGUeENCQ"},"schema":"pubphys.envelope/1"},"record_hash":"98c6a017fef356c21d6d6e49c16114be54d16dbca85640a1ebb22dfdcae2694b","leaf_index":2240}