• Media type: E-Article
  • Title: Measurement of eta meson decays into lepton-antilepton pairs
  • Contributor: Berlowski, M. [Author]; Bargholtz, Chr. [Author]; Fransson, K. [Author]; Gerén, L. [Author]; Gustafsson, L. [Author]; Höistad, B. [Author]; Ivanov, G. [Author]; Jacewicz, M. [Author]; Jiganov, E. [Author]; Johansson, T. [Author]; Keleta, S. [Author]; Koch, I. [Author]; Bashkanov, D. [Author]; Kullander, S. [Author]; Kupsc, A. [Author]; Kuzmin, A. [Author]; Kuznetsov, A. [Author]; Laukhin, I. V. [Author]; Lindberg, K. [Author]; Marciniewski, P. [Author]; Meier, R. [Author]; Morosov, B. [Author]; Oelert, W. [Author]; Bogolawsky, D. [Author]; [...]
  • Published: Soc., 2008
  • Published in: Physical review / D 77(3), 032004 (2008). doi:10.1103/PhysRevD.77.032004
  • Language: English
  • DOI: https://doi.org/10.1103/PhysRevD.77.032004
  • ISSN: 1550-7998
  • Keywords: eta: semileptonic decay ; eta --> pi+ pi- muon+ muon- ; eta --> 2lepton+ 2lepton- ; eta: leptonic decay ; experimental results ; eta --> positron electron photon ; eta: hadroproduction ; magnetic spectrometer: experimental results ; eta --> 2muon+ 2muon- ; eta --> 2positron 2electron ; eta --> positron electron ; eta: branching ratio ; upper limit ; p deuteron: exclusive reaction ; Uppsala CELSIUS Stor ; 0.893 GeV ; p deuteron --> helium-3 eta ; eta: decay modes ; lepton: pair production
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  • Description: 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 9.7x10(-5) (90% CL). The branching ratio for the decay eta -> e(+)e(-)gamma is determined to (7.8 +/- 0.5(stat)+/- 0.8(syst))x10(-3) in agreement with world average value. An upper limit (90% CL) for the branching ratio for the eta -> e(+)e(-) decay is 2.7x10(-5) and a limit for the sum of the eta ->mu(+)mu(-)mu(+)mu(-) and eta ->pi(+)pi(-)mu(+)mu(-) decays is 3.6x10(-4).
  • Access State: Open Access