Search for $\hat{I}\cdot$ and $\hat{I}{\cdot }^{\prime }$ Invisible Decays in $J/\ddot{I}ˆ\to \ddot{I}•\hat{I}\cdot$ and $\ddot{I}•\hat{I}{\cdot }^{\prime }$

Abstract

Using a sample of $(225.3\pm 2.8)\times 10^6$ $J/\ddot{I}ˆ$ decays collected with the BESIII detector at BEPCII, searches for invisible decays of $\hat{I}\cdot$ and $\hat{I}{\cdot }^{\prime }$ in $J/\ddot{I}ˆ\to \ddot{I}•\hat{I}\cdot$ and $\ddot{I}•\hat{I}{\cdot }^{\prime }$ are performed. Decays of $\ddot{I}•\to K^{+}{K}^{-}$ are used to tag the $\hat{I}\cdot$ and $\hat{I}{\cdot }^{\prime }$ decays. No signals above background are found for the invisible decays, and upper limits at the 90% confidence level are determined to be $2.58\times 10^{-4}$ for the ratio $\frac{\mathcal{B}(\hat{I}\cdot \to \mathrm{invisible})}{\mathcal{B}(\hat{I}\cdot \to {\hat{I}}^3{\hat{I}}^3)}$ and $2.39\times 10^{-2}$ for $\frac{\mathcal{B}(\hat{I}{\cdot }^{\prime }\to \mathrm{invisible})}{\mathcal{B}(\hat{I}{\cdot }^{\prime }\to {\hat{I}}^3{\hat{I}}^3)}$.

8 pages, 5 figures, and 2 tables, add more reference, changes made in introduction and conclusion Accepted by Phys. Rev. D; this the version for publication at PRD