{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"19691e9df0bdf31a7c13fc918fcd1161d773e178aa03cbf9a7cf4ebd04522b9e","created":"2026-10-03T07:18:05Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011","abde15c8ce0348cfcddbcfced9cdb9e83db5f20569ff8b484d8e25d5d199f364"],"salt":"25849676a4487ae5257080599b64564a776e03f27754774890849547dc7e9d42","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"hep.strong-cp.qcd-axion-existence","kind":"well-posed","literature_status":"open","n":"1","parents":[{"note":"","parent_revision":"abde15c8ce0348cfcddbcfced9cdb9e83db5f20569ff8b484d8e25d5d199f364","relation":"special_case"}],"plain":"The axion would be a very light, very weakly interacting particle that removes the strong CP puzzle. Detectors search for it turning into a photon inside strong magnets.","posed_since":"1978","precise":"Determine whether a pseudoscalar a with $m_a \\sim 5.7\\ \\mathrm{micro-eV}\\ (1e12\\ \\mathrm{GeV}/f_a)$ and photon coupling g_agamma inside the QCD axion band (KSVZ to DFSZ and beyond) exists, for $f_a\\ \\text{between}\\ \\sim 1e8\\ \\text{and}\\ \\sim 1e17\\ \\mathrm{GeV}$. An answer is a detection with $m_a$ and g_agamma consistent with the QCD mass-decay constant relation, or exclusion of the band over the full range.","problem_ref":null,"references":"","settled_by":"Haloscope, helioscope (IAXO) and nuclear-coupling (CASPEr-type) searches covering the QCD axion band across micro-eV to meV masses.","status_note":"Haloscopes reach DFSZ sensitivity only in narrow windows of a few micro-eV as of 2025.","title":"Does the QCD axion exist?","topic_ref":"417555880359201cc195a916f3b947e690164dade4e3ac924d6e5d98d0f88eb7"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"2b14938296c8ad1e49b251b2043ee7e420f8aee7ccd506042537a27815ad01d0","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"e2cfe5c726e83089ddeadc300e89d2638f34e40fd288f93486a8defa15f9cadc","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"_3UslUsBI6icBztObulZ7njh_TDFM4Tge5YycEyMGFTvPmRN28J6GeFgFrQq4bhOFZgP4GP95zvv_fHKE2xAAw"},"schema":"pubphys.envelope/1"},"record_hash":"2b14938296c8ad1e49b251b2043ee7e420f8aee7ccd506042537a27815ad01d0","leaf_index":1583}