2-7 June 2016
Auditorium Maximum
Europe/Warsaw timezone
14th International Workshop on Meson Production, Properties and Interaction
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Contribution

Auditorium Maximum - Medium lecture hall (A)

Search for the $C$-violating meson decay $\eta \rightarrow \pi^0 e^+ e^-$ with WASA-at-COSY

Speakers

  • Kay DEMMICH

Primary authors

  • Kay DEMMICH (Westfälische Wilhelms-Universität Münster)

Collaboration

WASA-at-COSY

Abstract content

The $C$-symmetry as well as the invariance of the electromagnetic and the strong interaction under a charge conjugation transformation are basic concepts of the standard model. The electromagnetic decay $\eta \rightarrow \pi^0 e^+ e^-$ via a virtual photon violates the $C$-parity and alternative $C$-conserving processes are strongly suppressed. Hence, the $\eta$-meson is a perfect probe to test the conservation of the $C$-parity whithin the standard model and gives rise to search for physics beyond the standard model, e.g., dark bosons. Since this decay has not yet been observed, only an upper limit of the branching ratio of $4\times 10^{-5}$ is quoted by the PDG. A huge data set of $\approx 5 \times 10^8$ $\eta$ mesons dedicated for studies on rare and forbidden $\eta$-decays has been recorded with the WASA-at-COSY setup, which allows for a determination of the relative branching ratio more sensitively than the recent upper limit. % The current status of the analysis will be presented.