Measurements of Branching Ratios for $\hat{I}\cdot$ Decays into Charged Particles

Abstract

The WASA-at-COSY experiment has collected $3\times 10^7$ events with $\hat{I}\cdot$-mesons produced via the reaction $pd\to {}^3\text{He}\hat{I}\cdot$ at $\text{T}=1.0\text{GeV}$. Using this data set, we evaluate the branching ratios of the decays $\hat{I}\cdot \to \ddot{I}{€}^{+}\ddot{I}{€}^{-}{\hat{I}}^3$, $\hat{I}\cdot \to e^{+}{e}^{-}{\hat{I}}^3$, $\hat{I}\cdot \to \ddot{I}{€}^{+}\ddot{I}{€}^{-}{e}^{+}{e}^{-}$ and $\hat{I}\cdot \to e^{+}{e}^{-}{e}^{+}{e}^{-}$. The branching ratios are normalized to the $\hat{I}\cdot \to \ddot{I}{€}^{+}\ddot{I}{€}^{-}\ddot{I}{€}^0$ decay. In addition an upper limit on a $CP$-violating asymmetry in $\hat{I}\cdot \to \ddot{I}{€}^{+}\ddot{I}{€}^{-}{e}^{+}{e}^{-}$ is extracted.