{"paper":{"title":"Measurement of eta meson decays into lepton-antilepton pairs","license":"","headline":"","cross_cats":[],"primary_cat":"hep-ex","authors_text":"A. Bondar, A. Kup\\'s\\'c, A. Kuzmin, A. Kuznetsov, A. Povtorejko, A. Turowiecki, A. Yamamoto, B. H\\\"oistad, B. Morosov, B. Shwartz, C. Ekstr\\\"om, CELSIUS/WASA Collaboration: M. Ber{\\l}owski, Chr. Bargholtz, C. Pauly, D. Bogoslawsky, E. Jiganov, F. Cappellaro, G. Ivanov, G.J. Wagner, H. Cal\\'en, H. Clement, H. Pettersson, I. Koch, I.V. Laukhin, I. Zartova, J. Stepaniak, J. Zabierowski, J. Z{\\l}oma\\'nczuk, K. Fransson, K. Lindberg, K. Sch\\\"onning, L. Demir\\\"ors, L. Ger\\'en, L. Gustafsson, M. Bashkanov, M. Jacewicz, M. Wolke, P.-E. Tegn\\'er, P. Marciniewski, P. Th\\\"orngren Engblom, R.J.M.Y. Ruber, R. Meier, R. Shafigullin, S. Keleta, S. Kullander, T. Johansson, T. Skorodko, V. Sopov, V. Tikhomirov, W. Oelert, W. Scobel, Y. Petukhov","submitted_at":"2007-11-23T20:47:49Z","abstract_excerpt":"A search for rare lepton decays of the eta meson was performed using the WASA detector at CELSIUS. Two candidates for double Dalitz decay eta->e+e-e+e- events are reported with a background of 1.3+/-0.2 events. This allows to set an upper limit to the branching ratio of 9.7E-5 (90% CL). The branching ratio for the decay eta->e+e-gamma is determined to (7.8+/-0.5 stat+/-0.8 syst)E-3. An upper limit (90% CL) for the branching ratio for the eta->e+e- decay is 2.7E-5 and a limit for the sum of the eta->mu+mu-mu+mu- and eta->pi+pi-mu+mu- decays is 3.6E-4."},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"0711.3531","kind":"arxiv","version":3},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"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"}