{"paper":{"title":"Search for Heavy Neutrinos in $\\pi \\to \\mu\\nu$ Decay","license":"http://arxiv.org/licenses/nonexclusive-distrib/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.H. Kettell, S. Ito, T. Numao, T. Sullivan, Y. Igarashi","submitted_at":"2019-04-05T20:40:18Z","abstract_excerpt":"Heavy neutrinos were sought in pion decays $\\pi^+ \\rightarrow \\mu^+ \\nu$ by examining the observed muon energy spectrum for extra peaks in addition to the expected peak for a massless neutrino. No evidence for heavy neutrinos was observed. Upper limits were set on the neutrino mixing matrix $|U_{\\mu i}|^2$ in the neutrino mass region of 15.7--33.8 MeV/c$^2$, improving on previous results by an order of magnitude."},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1904.03269","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/1904.03269/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"}