Measurement of eta meson decays into lepton-antilepton pairs

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 branc...

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Veröffentlicht in:	arXiv.org 2008-01
Hauptverfasser:	CELSIUS/WASA Collaboration, Berłowski, M, Bargholtz, Chr, Bashkanov, M, Bogoslawsky, D, Bondar, A, Calén, H, Cappellaro, F, Clement, H, Demirörs, L, Ekström, C, Fransson, K, Gerén, L, Gustafsson, L, Höistad, B, Ivanov, G, Jacewicz, M, Jiganov, E, Johansson, T, Keleta, S, Koch, I, Kullander, S, Kupść, A, Kuzmin, A, Kuznetsov, A, Laukhin, I V, Lindberg, K, Marciniewski, P, Meier, R, Morosov, B, Oelert, W, Pauly, C, Pettersson, H, Petukhov, Y, Povtorejko, A, R J M Y Ruber, Schönning, K, Scobel, W, Shafigullin, R, Shwartz, B, Skorodko, T, Sopov, V, Stepaniak, J, P -E Tegnér, Engblom, P Thörngren, Tikhomirov, V, Turowiecki, A, Wagner, G J, Wolke, M, Yamamoto, A, Zabierowski, J, Zartova, I, Złomańczuk, J
Format:	Artikel
Sprache:	eng
Schlagworte:	Eta-mesons Leptons Particle decay Physics - High Energy Physics - Experiment
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Zusammenfassung:	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.
ISSN:	2331-8422
DOI:	10.48550/arxiv.0711.3531