{"paper":{"title":"Measurement of Strange Quark Contributions to the Nucleon's Form Factors at Q^2=0.230 (GeV/c)^2","license":"","headline":"","cross_cats":[],"primary_cat":"nucl-ex","authors_text":"A4 Collaboration: F. E. Maas (1), A. Lopes Ginja (1), A. Lorente (1), B. Collin (3), B. Plaster (4), C. Weinrich (1), D. Marchand (3), D. von Harrach (1), E.-M. Kabuss (1), E. Schilling (1), G. Stephan (1), I. Altarev (2), J. Arvieux (3), J. Diefenbach (1), J. H. Lee (1), J. van de Wiele (3), K. Aulenbacher (1), K. Grimm (1), L. Capozza (1), L. Nungesser (1), M. Guidal (3), M. Morlet (3), P. Achenbach (1), R. Frascaria (3), R. Kothe (1), R. Kunne (3), R. Suleiman (4), S. Baunack (1), S. Kowalski (4), S. Ong (3), S. Taylor (4), T. Hammel (1), Y. Imai (1)","submitted_at":"2004-01-16T16:57:02Z","abstract_excerpt":"We report on a measurement of the parity-violating asymmetry in the scattering of longitudinally polarized electrons on unpolarized protons at a $Q^2$ of 0.230 (GeV/c)^2 and a scattering angle of \\theta_e = 30^o - 40^o. Using a large acceptance fast PbF_2 calorimeter with a solid angle of \\Delta\\Omega = 0.62 sr the A4 experiment is the first parity violation experiment to count individual scattering events. The measured asymmetry is A_{phys} =(-5.44 +- 0.54_{stat} +- 0.27_{\\rm sys}) 10^{-6}. The Standard Model expectation assuming no strangeness contributions to the vector form factors is $A_0"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"nucl-ex/0401019","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/nucl-ex/0401019/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}