{"paper":{"title":"European Strategy for Particle Physics Update -- PIONEER: a next generation rare pion decay experiment","license":"http://creativecommons.org/licenses/by/4.0/","headline":"","cross_cats":["nucl-ex","physics.ins-det"],"primary_cat":"hep-ex","authors_text":"A. Bolotnikov, A. Crivellin, A. Deshpande, A. Di Canto, A. Ebrahimi, A. Matsushita, A. Molnar, A. Seiden, A. Sher, A. Soter, A. Tricoli, B. Davis-Purcell, B. Schumm, B. Velghe, C. Glaser, C. Hamilton, C. Malbrunot, C. Zhang, D. Bryman, D. Hertzog, D. Pocanic, D. Ries, E. Klemets, E. Swanson, E. Worcester, G. Giacomini, J. Carlton, J. Datta, J. Ott, J. Yang, K. Frahm, K. Labe, K. Pachal, L. Caminada, L. Gerritzen, L. Gibbons, L. Kurchaninov, M. Chiu, M. Hoferichter, M. Worcester, O. Beesley, P. Fisher, PIONEER Collaboration: A. Adelmann, P. Kammel, P. Schwendimann, Q. Buat, R. Mischke, R. Roehnelt, R. Shrock, S. Ban, S. Chen, S. Corrodi, S. Cuen-Rochin, S. Foster, S. Heinekamp, S. Hochrein, S. Ito, S. Mehrotra, S.Mihara, S. M. Mazza, T. Brunner, T. Gorringe, T. Iwamoto, T. Mori, T. Numao, T. Rohe, T. Rostomyan, T. Sullivan, T. Tsang, U. Langenegger, V. Cirigliano, V. Tishchenko, W. Altmannshofer, W. Ootani, X. Qian, Y. Li, Y. Uchiyama, Y. Zhang","submitted_at":"2025-04-08T18:46:11Z","abstract_excerpt":"PIONEER is a rapidly developing effort aimed to perform a pristine test of lepton flavour universality (LFU) and of the unitarity of the first row of the CKM matrix by significantly improving the measurements of rare decays of the charged pion. In Phase I, PIONEER aims to measure the charged-pion branching ratio to electrons vs.\\ muons $R_{e/\\mu}$ to 1 part in $10^4$, improving the current experimental result $R_{e/\\mu}\\,\\text{(exp)} =1.2327(23)\\times10^{-4}$ by a factor of 15. This precision on $R_{e/\\mu}$ will match the theoretical accuracy of the SM prediction allowing for a test of LFU at "},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2504.06375","kind":"arxiv","version":2},"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/2504.06375/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"}