Measurement of eta meson decays into lepton-antilepton pairs

WASA Collaboration; M. Berłowski; Chr. Bargholtz; M. Bashkanov; D. Bogoslawsky; A. Bondar; H. Calén; F. Cappellaro; H. Clement; L. Demirörs; C. Ekström; K. Fransson; L. Gerén; L. Gustafsson; B. Höistad; G. Ivanov; M. Jacewicz; E. Jiganov; T. Johansson; S. Keleta; I. Koch; S. Kullander; A. Kupść; A. Kuzmin; A. Kuznetsov; I. V. Laukhin; K. Lindberg; P. Marciniewski; R. Meier; B. Morosov; W. Oelert; C. Pauly; H. Pettersson; Y. Petukhov; A. Povtorejko; R. J. M. Y. Ruber; K. Schönning; W. Scobel; R. Shafigullin; B. Shwartz; T. Skorodko; V. Sopov; J. Stepaniak; P. -E. Tegnér; P. Thörngren Engblom; V. Tikhomirov; A. Turowiecki; G. J. Wagner; M. Wolke; A. Yamamoto; J. Zabierowski; I. Zartova; J. Złomańczuk

doi:10.1103/physrevd.77.032004

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arXiv · 0711.3531

Measurement of eta meson decays into lepton-antilepton pairs

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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.

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WASA Collaboration, M. Berłowski, Chr. Bargholtz, M. Bashkanov, D. Bogoslawsky, A. Bondar, H. Calén, F. Cappellaro, H. Clement, L. Demirörs, C. Ekström, K. Fransson, L. Gerén, L. Gustafsson, B. Höistad, G. Ivanov, M. Jacewicz, E. Jiganov, T. Johansson, S. Keleta, I. Koch, S. Kullander, A. Kupść, A. Kuzmin, A. Kuznetsov, I. V. Laukhin, K. Lindberg, P. Marciniewski, R. Meier, B. Morosov, W. Oelert, C. Pauly, H. Pettersson, Y. Petukhov, A. Povtorejko, R. J. M. Y. Ruber, K. Schönning, W. Scobel, R. Shafigullin, B. Shwartz, T. Skorodko, V. Sopov, J. Stepaniak, P. -E. Tegnér, P. Thörngren Engblom, V. Tikhomirov, A. Turowiecki, G. J. Wagner, M. Wolke, A. Yamamoto, J. Zabierowski, I. Zartova, J. Złomańczuk. 2008-01-16. Measurement of eta meson decays into lepton-antilepton pairs. https://doi.org/10.1103/physrevd.77.032004

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