Observation of $\ddot{I}ˆ(3686)\to \hat{I}ž(1530{)}^0\bar{\hat{I}}ž(1530{)}^0$ and $\hat{I}ž(1530{)}^0\bar{\hat{I}}{ž}^0$

Abstract

Using $(448.1\pm 2.9)\times 10^6$ $\ddot{I}ˆ(3686)$ events collected with the BESIII detector and a single-baryon tagging technique, we present the first observation of the decays $\ddot{I}ˆ(3686)\to \hat{I}ž(1530{)}^0\bar{\hat{I}}ž(1530{)}^0$ and $\hat{I}ž(1530{)}^0\bar{\hat{I}}{ž}^0$. The branching fractions are measured to be $\mathcal{B}(\ddot{I}ˆ(3686)\to \hat{I}ž(1530{)}^0\bar{\hat{I}}ž(1530{)}^0)=(6.77\pm 0.14\pm 0.39)\times 10^{-5}$ and $\mathcal{B}(\ddot{I}ˆ(3686)\to \hat{I}ž(1530{)}^0\bar{\hat{I}}{ž}^0)=(0.53\pm 0.04\pm 0.03)\times 10^{-5}$. Here, the first and second uncertainties are statistical and systematic, respectively. In addition, the parameter associated with the angular distribution for the decay $\ddot{I}ˆ(3686)\to \hat{I}ž(1530{)}^0\bar{\hat{I}}ž(1530{)}^0$ is determined to be $\hat{I}\pm =0.32\pm 0.19\pm 0.07$, in agreement with theoretical predictions within one standard deviation.

10 pages, 5 figures