Measurement of the branching fraction of the decay $J/\ddot{I}ˆ\to p\bar{p}\hat{I}\cdot$

Abstract

A high precision measurement of the branching fraction of the decay $J/\ddot{I}ˆ\to p\bar{p}\hat{I}\cdot$ is performed using $(10087\pm 44)\times 10^6$ $J/\ddot{I}ˆ$ events recorded by the {BESIII} detector at the {BEPCII} storage ring. The branching fractions of the two decays $J/\ddot{I}ˆ\to p\bar{p}\hat{I}\cdot (\hat{I}\cdot \to {\hat{I}}^3{\hat{I}}^3)$ and $J/\ddot{I}ˆ\to p\bar{p}\hat{I}\cdot (\hat{I}\cdot \to \ddot{I}{€}^{+}\ddot{I}{€}^{-}\ddot{I}{€}^0)$ are measured individually to be $\mathcal{B}(J/\ddot{I}ˆ\to p\bar{p}\hat{I}\cdot (\hat{I}\cdot \to {\hat{I}}^3{\hat{I}}^3))=(1.480\pm 0.001\pm 0.024)\times 10^{-3}$ and $\mathcal{B}(J/\ddot{I}ˆ\to p\bar{p}\hat{I}\cdot (\hat{I}\cdot \to \ddot{I}{€}^{+}\ddot{I}{€}^{-}\ddot{I}{€}^0))=(1.557\pm 0.003\pm 0.038)\times 10^{-3}$, where the first uncertainties are statistical and the second systematic. Both results are compatible within their uncorrelated systematic uncertainties. The combined result is $\mathcal{B}(J/\ddot{I}ˆ\to p\bar{p}\hat{I}\cdot )=(1.495\pm 0.001\pm 0.023)\times 10^{-3}$ where the first uncertainty is the combined statistical uncertainty and the second one the combined systematic uncertainty of both analyses, incorporating correlations between them. In addition, the $p\bar{p}$ threshold region is investigated for a potential threshold enhancement, and no evidence for one is observed.