Study of $\psi(3770)$ decaying to Baryon anti-Baryon Pairs

Abstract

To study the decays of $\psi(3770)$ going to baryon anti-baryon pairs ($B\bar{B}$), all available experiments of measuring the cross sections of $e^+e^- \to B\bar{B}$ at center-of-mass energy ranging from 3.0 GeV to 3.9 GeV are combined. To relate the baryon octets, a model based on the SU(3) flavor symmetry is used and the SU(3) breaking effects are also considered. Assuming the elctric and magnetic form factors are equal ($|G_E|=|G_M|$), a global fit including the interference between the QED process and the resonant process is performed. The branching fraction of $\psi(3770) \to B\bar{B}$ is determined to be $(2.4\pm0.8\pm0.3)\times10^{-5}$, $(1.7\pm0.6\pm0.1)\times10^{-5}$, $(4.5\pm0.9\pm0.1)\times10^{-5}$, $(4.5\pm0.9\pm0.1)\times10^{-5}$, $(2.0\pm0.7\pm0.1)\times10^{-5}$, and $(2.0\pm0.7\pm0.1)\times10^{-5}$ for $B=p, \Lambda, \Sigma^+, \Sigma^0, \Xi^-$ and $\Xi^0$, respectively, where the first uncertainty is from the global fit and the second uncertainty is the systematic uncertainty due to the assumption $|G_E|=|G_M|$. They are at least one order of magnitude larger than a simple scaling of the branching fraction of $J/\psi\to B\bar{B}$.