{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"01e0e8dabf3e1fc00bc759ad2a5a16e1adfa1a9250da3d8b9a65c33ea11f8b23","created":"2026-10-03T07:18:07Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011","58e430b37105a7ee04896df7e09da38151b5a1073a3284062adbf2d3bc0ab888"],"salt":"582a60652913e6a78eaac42db7e09062b3db1a766b599c339ff5e4ec6c9c17fb","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"nuc.proton-structure.gluon-helicity","kind":"well-posed","literature_status":"open","n":"1","parents":[{"note":"","parent_revision":"58e430b37105a7ee04896df7e09da38151b5a1073a3284062adbf2d3bc0ab888","relation":"special_case"}],"plain":"Gluons, the particles that bind quarks, can carry spin aligned with the proton's. Collider data show a positive contribution from medium-momentum gluons, but the part from very low-momentum gluons is unknown.","posed_since":"","precise":"Determine $\\Delta G(\\mu^{2})=\\operatorname{integral}_{0}^{1}\\mathrm{d}x\\ \\Delta g(x,\\mu^{2})$ at $\\mu^{2}=10\\ \\mathrm{GeV}^{2}$, where $\\Delta g$ is the gluon helicity distribution and x the gluon momentum fraction. RHIC polarized pp data give $\\operatorname{integral}_{0.05}^{0.2}\\Delta g\\ \\mathrm{d}x=0.20\\ (+0.06,-0.07)$ (de Florian et al., 2014) under a positivity assumption; the open part is $x<0.01$, where no data exist, together with the residual dependence of the sign on high-x and $\\mathrm{SU}(3)$ assumptions. Answer: $\\Delta G$ with total uncertainty below 0.05.","problem_ref":null,"references":"","settled_by":"Scaling violations of the polarized structure function $g_{1}$ measured at the EIC over $1e-4 < x < 0.5$, combined in a global fit with RHIC data.","status_note":"Fits without positivity admitted negative $\\Delta g$ (JAM, 2022); lattice Ioffe-time data could not fix the sign (Karpie et al., 2023), but adding high-x polarized DIS data disfavored the negative solution (Hunt-Smith et al., 2024); the $x < 0.01$ contribution remained unmeasured as of 2026.","title":"Total gluon spin contribution $\\Delta G$ to the proton spin","topic_ref":"43e6b835146db14bd1b426a6a865acb8bf50720a1000b6a2c5c5d637adc5063d"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"65cad78542e44a39679ea3d379ed3054dc7d8a4646c2b5074fca3f9f2164231f","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"785621152e934631b75ad066f5b59df0235a68b55bdf68e2aabf912cabbeccde","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"tR3TazOBnTTuAL5I10JsRhElUbjOZyOGf55Vwpg6rrFQNm7XTg4Wk2XU4u94RiF58bIq_A3uJ04SP9YTuqWHCw"},"schema":"pubphys.envelope/1"},"record_hash":"65cad78542e44a39679ea3d379ed3054dc7d8a4646c2b5074fca3f9f2164231f","leaf_index":1796}