Darmstadt 2016 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 16: Hadron Structure and Spectroscopy III
HK 16.6: Vortrag
Dienstag, 15. März 2016, 15:30–15:45, S1/01 A5
Upper limit determination of the η-decay η→π0 + e+ + e− with WASA-at-COSY* — •Florian Bergmann, Kay Demmich, Nils Hüsken, Karsten Sitterberg, and Alfons Khoukaz for the WASA-at-COSY collaboration — Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Germany
Investigations on symmetries and symmetry breaking is a major part of the
WASA-at-COSY physics program. They allow for a better understanding of the
physics within the standard model. An elegant way to search for violation of
conservation laws, which are directly connected to symmetry breaking effects,
is the study of rare meson decays. At the WASA-at-COSY facility an extensive
physics program on η-meson decays has been performed with high statistics
which are required to obtain new limits on, e.g., the C, P and T symmetry
breaking or combinations thereof.
In this contribution the status of the analysis of the C-violating
η-decay η→π0 + e+ + e− using the high statistics
p+d→3He+η data obtained with WASA-at-COSY will be presented
and discussed. The dominant C-conserving contribution to this decay
via a π0+γ*+γ* intermediate state has an expected branching
ratio of less than 10−8 in the standard model. An observation of a
significantly higher branching ratio would indicate the presence of a
C-violating process.
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*Supported by FFE program of the Forschungszentrum Jülich.