Measurement of $\hat{I}“(\hat{I}\cdot \to \ddot{I}{€}^{+}\ddot{I}{€}^{-}{\hat{I}}^3)/\hat{I}“(\hat{I}\cdot \to \ddot{I}{€}^{+}\ddot{I}{€}^{-}\ddot{I}{€}^0)$ with KLOE experiment

Abstract

We report the measurement of the ratio $\hat{I}“(\hat{I}\cdot \to \ddot{I}{€}^{+}\ddot{I}{€}^{-}{\hat{I}}^3)/\hat{I}“(\hat{I}\cdot \to \ddot{I}{€}^{+}\ddot{I}{€}^{-}\ddot{I}{€}^0)$ analyzing a large sample of $\ddot{I}•\to \hat{I}\cdot {\hat{I}}^3$ decays recorded with the KLOE experiment at the DA$\hat{I}¦$NE $e^{+}{e}^{-}$ collider, corresponding to an integrated luminosity of 558 pb${}^{-1}$. The $\hat{I}\cdot \to \ddot{I}{€}^{+}\ddot{I}{€}^{-}{\hat{I}}^3$ process is supposed to proceed both via a resonant contribution, mediated by the $\ddot{I}$ meson, and a non resonant direct term, connected to the box anomaly. The presence of the direct term affects the partial width value. Our result $R_{\hat{I}}\cdot =\hat{I}“(\hat{I}\cdot \to \ddot{I}{€}^{+}\ddot{I}{€}^{-}{\hat{I}}^3)/\hat{I}“(\hat{I}\cdot \to \ddot{I}{€}^{+}\ddot{I}{€}^{-}\ddot{I}{€}^0)=0.1838\pm 0.0005_{stat}\pm 0.0030_{syst}$ is in agreement with a recent CLEO measurement, which differs by more 3 $\ddot{I}ƒ$ from the average of previous results.