{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"787d359bcafc566ddd72d441562558ae8368b92290dd91aa3bd3d3c87b4a8883","created":"2026-10-03T07:18:07Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"9989f2efbfe1d1d16edd74db988d1c8c76ec72ffe8591b115cace75f23491169","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"nuc.emc-src.src-repulsive-core","kind":"well-posed","literature_status":"partially-resolved","n":"1","parents":[],"plain":"Close nucleon pairs are mostly proton-neutron pairs because of the tensor force (a force depending on spin orientation). At still shorter distance all pairs should feel a hard repulsion that treats them alike, and locating this switch tests the nuclear force at short range.","posed_since":"","precise":"In hard two-nucleon knockout $\\left(e, e' p N\\right)$ on nuclei from 4He to 208Pb, measure the $\\mathrm{pp}/\\mathrm{np}$ pair ratio as a function of relative momentum $k$ from $0.3\\text{ to }1.0\\,\\mathrm{GeV}/c$. Answer: the momentum at which the ratio rises from about $1/20$ toward the spin-isospin-independent value, and whether NN interactions (chiral EFT and phenomenological) reproduce it within the generalized contact formalism.","problem_ref":null,"references":"","settled_by":"High-statistics $(e, e' p N)$ data above $k = 0.6\\,\\mathrm{GeV}/c$ at JLab $12\\,\\mathrm{GeV}$ with final-state-interaction corrections.","status_note":"CLAS data indicated a rise of the pp/np ratio above about 600 MeV/c (Schmidt et al., Nature 2020), with limited statistics at the highest momenta.","title":"Onset of the repulsive core in short-range correlated pairs","topic_ref":"7a074c9c279467b77e19375da4dad17647254ffcdf3c39de667bd47e1e1c500e"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"a0050e816e5426374b54bf2892ceed55c5c218daaff989b837b6ba7758e4fafe","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"adda349195aa54a69463c89f0bfe747bfb9e4171ef82ac1ea4314cccb3f836a8","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"YNDCxP3zZpKcZ9Dk7gwmhEi6N3KOPxKQs3kttrhOP6kPoEwyLpjCm3Y30ei7D1kv3tZ7w79lnW3AEthoqZEsCQ"},"schema":"pubphys.envelope/1"},"record_hash":"a0050e816e5426374b54bf2892ceed55c5c218daaff989b837b6ba7758e4fafe","leaf_index":1743}