{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"1871c5c65a6f9bbf79935d0a3a3e52588f7593713e7cf24d42af6fdedeb5c329","created":"2026-10-03T07:18:07Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"5f11b38e1258c075b9ddef5417828525690a441e6203a5239ada3a6caa474507","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"nuc.proton-structure.gluon-gravitational-form-factors","kind":"well-posed","literature_status":"contested","n":"1","parents":[],"plain":"How mass and pressure are spread inside the proton can be read from its response to gravity-like probes, approximated in practice by producing heavy $J/\\psi$ mesons just above threshold. Early extractions disagree on whether mass is more concentrated than charge.","posed_since":"","precise":"Determine the gluon gravitational form factors $A_{g}(t)$, $B_{g}(t)$, $D_{g}(t)$ for $-t < 2\\,\\mathrm{GeV}^{2}$ and the resulting mass and scalar radii. Near-threshold $J/\\psi$ photoproduction data from GlueX and JLab Hall C (2019 to 2023) were interpreted with holographic and GPD models giving different radii. Answer: a model-independent extraction, or a demonstration that threshold $J/\\psi$ production cannot determine these form factors at 10 percent accuracy.","problem_ref":null,"references":"","settled_by":"Lattice QCD calculation of $A_{g}$ and $D_{g}$ at physical pion mass compared with threshold $J/\\psi$ and $\\Upsilon$ production at JLab and the EIC, with the reaction mechanism (two-gluon exchange versus open-charm intermediate states) fixed by data.","status_note":"Extractions from the 2023 JLab data depended on whether the reaction proceeds through two-gluon exchange or open-charm loops, which remained unresolved as of 2026.","title":"Gluon gravitational form factors and the proton mass radius","topic_ref":"43e6b835146db14bd1b426a6a865acb8bf50720a1000b6a2c5c5d637adc5063d"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"38d1f92196f6eccc0cbbec99a0384b3d9afdaf4c06307c14d5b9324730642721","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"1bdfef7353a9102339e8c496e232d8d8c9a992986a17dd6993e295ffb755ec35","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"40_73jS9TSOZYRI7ocYMGg-r5ObC3_K5u31vDD9jsAHRrinCqhBxjgi-DC7SpfY7oiFWIOYr7Yh3Elpes1o4CQ"},"schema":"pubphys.envelope/1"},"record_hash":"38d1f92196f6eccc0cbbec99a0384b3d9afdaf4c06307c14d5b9324730642721","leaf_index":1792}