Search for the $\hat{I}{\cdot }_c(2S)/h_c\to p\bar{p}$ decays and measurements of the $\ddot{I}{‡}_{cJ}\to p\bar{p}$ branching fractions

Abstract

Using a sample of $1.06\times 10^8\ddot{I}ˆ(3686)$ events collected with the BESIII detector at BEPCII, the decays $\hat{I}{\cdot }_c(2S)\to p\bar{p}$ and $h_c\to p\bar{p}$ are searched for, where $\hat{I}{\cdot }_c(2S)$ and $h_c$ are reconstructed in the decay chains $\ddot{I}ˆ(3686)\to {\hat{I}}^3\hat{I}{\cdot }_c(2S)$, $\hat{I}{\cdot }_c(2S)\to p\bar{p}$ and $\ddot{I}ˆ(3686)\to \ddot{I}{€}^0{h}_c$, $h_c\to p\bar{p}$, respectively. No significant signals are observed. The upper limits of the product branching fractions are determined to be $\mathcal{B}(\ddot{I}ˆ(3686)\to {\hat{I}}^3\hat{I}{\cdot }_c(2S))\times \mathcal{B}(\hat{I}{\cdot }_c(2S)\to p\bar{p})<1.4\times 10^{-6}$ and $\mathcal{B}(\ddot{I}ˆ(3686)\to \ddot{I}{€}^0{h}_c)\times \mathcal{B}(h_c\to p\bar{p})<1.3\times 10^{-7}$ at the 90% C.L.. The branching fractions for $\ddot{I}{‡}_{cJ}\to p\bar{p}$ $(J=0,1,2)$ are also measured to be $(24.5\pm 0.8\pm 1.3,8.6\pm 0.5\pm 0.5,8.4\pm 0.5\pm 0.5)\times 10^{-5}$, which are the world's most precise measurements.