4 research outputs found
Tests of the fundamental symmetries in eta meson decays
Patterns of chiral symmetry violation and tests of the conservation of the
fundamental C, P and CP symmetries are key physics issues in studies of the
pi0, eta and eta' meson decays. These tests include searches for rare or
forbidden decays and searches for asymmetries among the decay products in the
not-so-rare decays. Some examples for the rare decays are eta-->2pi, eta-->4pi0
(CP tests), decays into an odd number of photons (e.g., eta-->3g) and the decay
eta-->pi0e+e- (C tests). The experimental studies of the pi0, eta and eta'
meson decays are carried out at four European accelerator research facilities:
KLOE/KLOE-2 at DAFNE (Frascati), Crystal Ball at MAMI (Mainz), WASA at COSY
(J\"ulich), Crystal Barrel at ELSA (Bonn).Comment: 9 pages, 2 figures, proceedings of Symposium on Prospects in the
Physics of Discrete Symmetries, DISCRETE 2010, 6 - 11 December, Rome; v2:
added reference
Measurement of the eta->pi+pi-e+e- decay branching ratio
The reaction pd->3He eta at threshold was used to provide a clean source of
eta mesons for decay studies with the WASA detector at CELSIUS. The branching
ratio of the decay eta->pi+pi-e+e- is measured to be (4.3+/-1.3+/-0.4)x10^-4.Comment: 10 pages,6 figures revised versio
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 9.7x10(-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)