Upper limit on the $\eta \to {\pi }^{+}{\pi }^{-}$ branching fraction with the KLOE experiment

D. Babusci, M. Berlowski, C. Bloise +53

Based on an integrated luminosity of 1.61 fb${}^{-1}$ $e^{+}{e}^{-}$ collision data collected with the KLOE detector at DA$\Phi$NE, the Frascati $\varphi$-factory, a search for the $P$- and $CP$-vi…