1. Measurement of eta meson decays into lepton-antilepton pairs
- Author
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Collaboration, CELSIUS/WASA, 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., Ruber, R. J. M. Y., Schönning, K., Scobel, W., Shafigullin, R., Shwartz, B., Skorodko, T., Sopov, V., Stepaniak, J., Tegnér, P. -E., Engblom, P. Thörngren, Tikhomirov, V., Turowiecki, A., Wagner, G. J., Wolke, M., Yamamoto, A., Zabierowski, J., Zartova, I., and Złomańczuk, J.
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High Energy Physics - Experiment - Abstract
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., Comment: 9 pages, 10 Postscript figures, uses revtex4.sty, revised version after referee comments; conclusions unchanged
- Published
- 2007
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