{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"2bce910b32a52b52742ba8d2c6636d5d55238641bcc4fe0ba8de125e4d9b11bc","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b","eee838117fc834ffd707dff485f8bb9d14bb86714af6437138b52ce79d39b448"],"salt":"e9bd6399caa85a862af58ce6920580b1388b5681bf46374c7ec6755fce3179aa","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"classification","assisted_by":[],"external_id":"qft.cft-rg.five-d-on","kind":"well-posed","literature_status":"contested","n":"2","parents":[],"plain":"In five dimensions, a model of N-component spins may have a scale-invariant point that appears only at short distances. Whether this point is a consistent quantum theory for realistic N is unknown.","posed_since":"","precise":"The $O(N)$ model in $4 < d < 6$ has a UV fixed point at large N, equivalently described by the cubic theory of Fei, Giombi and Klebanov. Determine whether for any finite N in $d = 5$ it is a unitary CFT, or whether it is non-unitary (complex or metastable) for all finite N through instanton effects; if unitary fixed points exist, find the smallest such N.","problem_ref":"eee838117fc834ffd707dff485f8bb9d14bb86714af6437138b52ce79d39b448","references":"","settled_by":"Numerical bootstrap islands or exclusions for the 5D O(N) CFT as a function of N, consistent with large-N data, or a proof that nonperturbative instability persists at every finite N.","status_note":"Large-$N$ and $6 - \\epsilon$ expansions support existence at large $N$; bootstrap kinks are weak and instanton arguments (2019) suggest the fixed point is at best metastable.","title":"Does an interacting unitary O(N) CFT exist in five dimensions?","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"22110a6ccdfb720d3bad5bb0a57da5e8e09ca7acf4914ccaa923e630af3f87fd","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"b93cda31b2354cf47e03e1ad08480436173d4feae1f94ecdd720213cfb4c9704","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"MQxIKLrwbKLJXrIJyN_x1tqOqMUS5Y8eEOKHiF2qIlys7UGLyjWH97vzyup6AEcRnP4nu8bMMOelJb05H4djAg"},"schema":"pubphys.envelope/1"},"record_hash":"22110a6ccdfb720d3bad5bb0a57da5e8e09ca7acf4914ccaa923e630af3f87fd","leaf_index":3626}