{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"febe01bd3606a1cc1eb254e67286a9070c82b3fe2dcc3d3942d26df46b615820","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":["ai:gpt-5.5"],"kind":"seed"},"parents":["ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b","f37258440f5eea6b92f608d1bc5bee4825cf0d2a1d193e1f29a4d2312b5ac60d"],"salt":"42f70e6869303087ac2c97c9189ab527961bed2aa2b9cb6a430c93f096db7e53","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":["ai:gpt-5.5"],"external_id":"nuc.neutrino-nucleus.pion-production","kind":"phenomenon","literature_status":"contested","n":"2","parents":[],"plain":"In the few-GeV range many neutrino collisions make a pion, often through a short-lived excited nucleon called the $\\Delta$. Measurements from different experiments and the models used to describe them do not agree, especially for slow pions and small momentum transfers.","posed_since":"","precise":"Construct a model of charged- and neutral-current single-pion production on 12C, 16O and 40Ar for $E_{\\nu} = 0.5\\ \\text{to}\\ 5\\ \\mathrm{GeV}$ that simultaneously reproduces MiniBooNE, MINERvA and T2K pion kinematic distributions, including the low-$Q^2$ suppression and the pion absorption and charge exchange in the nucleus. The answer must identify the physics (in-medium $\\Delta$ properties, nonresonant background, final-state interactions, flux normalization) responsible for the inter-experiment tension.","problem_ref":"f37258440f5eea6b92f608d1bc5bee4825cf0d2a1d193e1f29a4d2312b5ac60d","references":"","settled_by":"A single model, constrained by pion electroproduction and hydrogen or deuterium neutrino data, that fits all nuclear-target pion data within quoted uncertainties.","status_note":"","title":"Reliable models of neutrino pion production on nuclei","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"91996fff71c4db825e6f48421d23cb49e06367a498d6379f615418125117e383","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"1d9b97282cd8eaa9e5170c59febda618b84f41f043d6d63d597f1e0d6f4f97ab","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"0ZTkkoZM9GZatiWIgZqznKanqvJfqMpkZLzn4hbsByDibTstNXNu-LSPcDzjPmB0bzzVgn--MhyvY-iAoVNyDg"},"schema":"pubphys.envelope/1"},"record_hash":"91996fff71c4db825e6f48421d23cb49e06367a498d6379f615418125117e383","leaf_index":3506}