{"paper":{"title":"Search for lepton flavour violating muon decay mediated by a new light particle in the MEG experiment","license":"http://creativecommons.org/licenses/by/4.0/","headline":"","cross_cats":[],"primary_cat":"hep-ex","authors_text":"A. Corvaglia, A. De Bari, A. Kolesnikov, A. M. Baldini, A. Mtchedilishvili, A. Oya, A. Papa, A. Popov, A. Rozhdestvensky, A. Stoykov, C. Chiri, C. Voena, D. N. Grigoriev, D. Nicol\\`o, D. Palo, F. Berg, F. Cei, F. Gatti, F. Grancagnolo, F. Ignatov, F. Renga, G. Boca, G. Cavoto, G. Chiarello, G. F. Tassielli, G. M. A. Lim, G. Pizzigoni, G. Signorelli, H. Natori, H. Nishiguchi, K. Ieki, K. Toyoda, K. Yanai, L. Galli, M. Biasotti, M. Chiappini, M. De Gerone, M. Francesconi, M. Grassi, M. Hildebrandt, M. Meucci, M. Nakao, M. Nishimura, M. Panareo, M. Rossella, M. Usami, N. Khomutov, N. Kravchuk, N. Kuchinskiy, N. Matsuzawa, P.-R. Kettle, P. Schwendimann, P. W. Cattaneo, R. Iwai, R. Onda, R. Sawada, S. Kobayashi, S. Mihara, S. Ogawa, S. Ritt, T. Iwamoto, T. Libeiro, Toshinori Mori, V. Malyshev, V. Pettinacci, W. Kyle, W. Molzon, W. Ootani, Y. Uchiyama, Yu.V. Yudin, Z. Hodge","submitted_at":"2020-05-01T12:29:41Z","abstract_excerpt":"We present the first direct search for lepton flavour violating muon decay mediated by a new light particle X, $\\mu^+ \\to \\mathrm{e}^+\\mathrm{X}, \\mathrm{X} \\to \\gamma\\gamma$. This search uses a dataset resulting from $7.5\\times 10^{14}$ stopped muons collected by the MEG experiment at the Paul Scherrer Institut in the period 2009--2013. No significant excess is found in the mass region 20--45 MeV/c$^2$ for lifetimes below 40 ps, and we set the most stringent branching ratio upper limits in the mass region of 20--40 MeV/c$^2$, down to $\\mathcal{O}(10^{-11})$ at 90\\% confidence level."},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2005.00339","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/2005.00339/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"}