First observation of $\ddot{I}ˆ(2S)\to p\bar{n}\ddot{I}{€}^{-}+c.c.$

Abstract

Using 14 million $\ddot{I}ˆ(2S)$ events collected with the Beijing Spectrometer (BESII) at the Beijing Electron-Positron Collider, the branching fractions of $\ddot{I}ˆ(2S)$ decays to $p\bar{n}\ddot{I}{€}^{-}$ and $\bar{p}n\ddot{I}{€}^{+}$ and the branching fractions of the main background channels $\ddot{I}ˆ(2S)\to p\bar{n}\ddot{I}{€}^{-}\ddot{I}{€}^0$, $\ddot{I}ˆ(2S)\to {\hat{I}}^3\ddot{I}{‡}_{c0}\to {\hat{I}}^{3}p\bar{n}\ddot{I}{€}^{-}$, $\ddot{I}ˆ(2S)\to {\hat{I}}^3\ddot{I}{‡}_{c2}\to {\hat{I}}^{3}p\bar{n}\ddot{I}{€}^{-}$, and $\ddot{I}ˆ(2S)\to {\hat{I}}^3\ddot{I}{‡}_{cJ}\to {\hat{I}}^{3}p\bar{n}\ddot{I}{€}^{-}\ddot{I}{€}^0$ are determined. The contributions of the $N^{\ast }$ resonances in $\ddot{I}ˆ(2S)\to p\bar{n}\ddot{I}{€}^{-}+c.c.$ are also discussed.

19 pages, 8 figures, add vertex requirement systematic error