학술논문
Measurement of eta meson decays into lepton-antilepton pairs
Document Type
Working Paper
Author
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.; Złomańczuk, J.
Source
Subject
Language
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
Comment: 9 pages, 10 Postscript figures, uses revtex4.sty, revised version after referee comments; conclusions unchanged