Measurements of $J/\ddot{I}ˆ$ and $\ddot{I}ˆ(2S)$ decays into $\hat{I}›\bar{\hat{I}}›\ddot{I}{€}^0$ and $\hat{I}›\bar{\hat{I}}›\hat{I}\cdot$

Abstract

Using 58 million $J/\ddot{I}ˆ$ and 14 million $\ddot{I}ˆ(2S)$ events collected by the BESII detector at the BEPC, branching fractions or upper limits for the decays $J/\ddot{I}ˆ$ and $\ddot{I}ˆ(2S)\to \hat{I}›\bar{\hat{I}}›\ddot{I}{€}^0$ and $\hat{I}›\bar{\hat{I}}›\hat{I}\cdot$ are measured. For the isospin violating decays, the upper limits are determined to be $\mathcal{B}(J/\ddot{I}ˆ\to \hat{I}›\bar{\hat{I}}›\ddot{I}{€}^0)<6.4\times 10^{-5}$ and $\mathcal{B}(\ddot{I}ˆ(2S)\to \hat{I}›\bar{\hat{I}}›\ddot{I}{€}^0)<4.9\times 10^{-5}$ at the 90% confidence level. The isospin conserving process $J/\ddot{I}ˆ\to \hat{I}›\bar{\hat{I}}›\hat{I}\cdot$ is observed for the first time, and its branching fraction is measured to be $\mathcal{B}(J/\ddot{I}ˆ\to \hat{I}›\bar{\hat{I}}›\hat{I}\cdot )=(2.62\pm 0.60\pm 0.44)\times 10^{-4}$, where the first error is statistical and the second one is systematic. No $\hat{I}›\bar{\hat{I}}›\hat{I}\cdot$ signal is observed in $\ddot{I}ˆ(2S)$ decays, and $\mathcal{B}(\ddot{I}ˆ(2S)\to \hat{I}›\bar{\hat{I}}›\hat{I}\cdot )<1.2\times 10^{-4}$ is set at the 90% confidence level. Branching fractions of $J/\ddot{I}ˆ$ decays into $\hat{I}{\pounds }^{+}\ddot{I}{€}^{-}bar\hat{I}›$ and $\bar{\hat{I}}{\pounds }^{-}\ddot{I}{€}^{+}\hat{I}›$ are also reported, and the sum of these branching fractions is determined to be $\mathcal{B}(J/\ddot{I}ˆ\to \hat{I}{\pounds }^{+}\ddot{I}{€}^{-}\bar{\hat{I}}›+c.c.)=(1.52\pm 0.08\pm 0.16)\times 10^{-3}$.

7 pages, 10 figures. Phys.Rev.D comments considered