{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"dcf6d0c6bf836a0fb4e2ffe409031f460a6608398f2e7d65a252006c08a8e180","created":"2026-10-03T07:18:09Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"8c271b80af70e9c573602f786b0134b2eaf05be46e7d7cf279081d55393610c1","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"qft.massless-bootstrap.large-n-pion-kink","kind":"well-posed","literature_status":"open","n":"1","parents":[],"plain":"Bounds on how massless pions can scatter when the number of colors is large show a sharp corner. Whether QCD with many colors lies exactly at that corner is unknown.","posed_since":"2022","precise":"Albert and Rastelli (JHEP 08 (2022) 151) bounded ratios of chiral-Lagrangian Wilson coefficients for massless pions in large-N confining gauge theories, using tree-level meson exchange, crossing, unitarity and Regge behavior, and found a kink on the exclusion boundary. Determine whether the large-N QCD values of these ratios (from lattice QCD at large N or other controlled methods) coincide with the kink, and what meson spectrum the extremal amplitude has.","problem_ref":null,"references":"","settled_by":"Large-N lattice determination of the relevant Wilson-coefficient ratios compared with the kink location.","status_note":"Albert and Rastelli (2022) raised and critically examined the identification; Albert, Henriksson, Rastelli and Vichi (arXiv:2312.15013, 2023) found, under a spin-2 spectral assumption, an extremal amplitude with an apparent Regge trajectory close to real meson masses; no large-N lattice comparison settles it as of 2026.","title":"Does large-N QCD lie at the pion bootstrap kink","topic_ref":"ec37b6151c82884c89bcd0edd8abd842fda27798c1918aa964b247ee16f12213"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"5713935226206badad55efaef2ace77306bd0d0aa0e0c96c87ecb383f9234ddb","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"7fecfc25b0c008a7b8320501b79e2566c3f4e21eb81b3def03de7d1f95868919","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"QDofrb42CnkDOJD4BdBJiWogJyfPUpTp1cH3PfvTfQGtequpSbPcQExfQDMgqUT59O_2sILBzFS26pJhg7rHAw"},"schema":"pubphys.envelope/1"},"record_hash":"5713935226206badad55efaef2ace77306bd0d0aa0e0c96c87ecb383f9234ddb","leaf_index":1924}