{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"5f6781e7c0e68e5d05bc40d291dd5c639a2dc49462217abc21b3c1943fee9d52","created":"2026-10-03T07:18:08Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"b8d2778391d4228e56b8301230dd6fbf916a25a8d7e77dc7ad07ec1dcd5cffa9","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":"1","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":null,"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":"59b3cca1f32dc01e525b6517c866b60ced9512aa01bc51694ea2f6fc00c1ca06"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"eee838117fc834ffd707dff485f8bb9d14bb86714af6437138b52ce79d39b448","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"337f064878429013b30d43938916961ddd8424b27ba3da4157e3e0571052dab5","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"nKyD5WXL2SfFJM_z_M2QL0GxzAFdSLDy4QIn8QVOYIl8P9GTaCyDxsQadkLoISVCkOxyFkX0Le0RAlElftwtBA"},"schema":"pubphys.envelope/1"},"record_hash":"eee838117fc834ffd707dff485f8bb9d14bb86714af6437138b52ce79d39b448","leaf_index":1892}