{"paper":{"title":"Search for three body pion decays ${\\pi}^+{\\to}l^+{\\nu}X$","license":"http://creativecommons.org/publicdomain/zero/1.0/","headline":"","cross_cats":[],"primary_cat":"hep-ex","authors_text":"A. Aguilar-Arevalo, A. Hussein, A. Sher, C. Malbrunot, D.A. Bryman, D.I. Britton, D. Protopopescu, D. Vavilov, D. vom Bruch, J. Comfort, L. Doria, L. Kurchaninov, L.S. Littenberg, M. Aoki, M. Blecher, P. Gumplinger, R.E. Mischke, S. Chen, S. Cuen-Rochin, S. Ito, S. Kettell, T. Numao, T. Sullivan, Y. Igarashi","submitted_at":"2021-01-18T23:59:13Z","abstract_excerpt":"The three body pion decays ${\\pi}^+{\\rightarrow}l^+{\\nu}X~(l=e,{\\mu})$, where $X$ is a weakly interacting neutral boson, were searched for using the full data set from the PIENU experiment. An improved limit on ${\\Gamma}({\\pi}^+{\\to}e^+{\\nu}X)/{\\Gamma}({\\pi}^+{\\to}{\\mu}^+{\\nu}_{\\mu})$ in the mass range $0<m_X<120$ MeV/$c^2$ and a first result for ${\\Gamma}({\\pi}^+{\\to}{\\mu}^+{\\nu}X)/{\\Gamma}({\\pi}^+{\\to}{\\mu}^+{\\nu}_{\\mu})$ in the region $0<m_X<33.9$ MeV/$c^2$ were obtained. The Majoron-neutrino coupling model was also constrained using the current experimental result of the ${\\pi}^+{\\to}e^+{\\"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2101.07381","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/2101.07381/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"}