Observation and branching fraction measurements of $J/\ddot{I}ˆ\to p\bar{p}{K}_S^0{K}_S^0$ and $\ddot{I}ˆ(3686)\to p\bar{p}{K}_S^0{K}_S^0$

Abstract

Using $(10.087\pm 0.044)\times 10^9$ $J/\ddot{I}ˆ$ events and $(2.712\pm 0.014)\times 10^9$ $\ddot{I}ˆ(3686)$ events collected by the BESIII detector operating at the BEPCII collider, we report the first observation of the hadronic decays of $J/\ddot{I}ˆ\to p\bar{p}{K}_S^0{K}_S^0$ and $\ddot{I}ˆ(3686)\to p\bar{p}{K}_S^0{K}_S^0$, both with statistical significance greater than $10\ddot{I}ƒ$. Their branching fractions are determined to be $\mathcal{B}(J/\ddot{I}ˆ\to p\bar{p}{K}_S^0{K}_S^0)=(1.60\pm 0.02\pm 0.09)\times 10^{-5}$ and $\mathcal{B}(\ddot{I}ˆ(3686)\to p\bar{p}{K}_S^0{K}_S^0)=(3.93\pm 0.24\pm 0.34)\times 10^{-6}$. The ratio of their branching fractions is $\mathcal{B}(\ddot{I}ˆ(3686)\to p\bar{p}{K}_S^0{K}_S^0)/\mathcal{B}(J/\ddot{I}ˆ\to p\bar{p}{K}_S^0{K}_S^0)=(24.6\pm 1.5\pm 2.1)\%$, which deviates from theoretical expectation by 4.6$\ddot{I}ƒ$. Here the first uncertainties are statistical and the second systematic. We have also examined the $p\bar{p}$ invariant mass distributions in these decays, and no significant enhancement around the $p\bar{p}$ near threshold is found.