Study of $e^+e^- \rightarrow \Sigma^0 \overline{\Sigma}{}^0$ and $\Sigma^+\overline{\Sigma}{}^- $ by Initial State Radiation Method at Belle

The processes $ e^+e^-\rightarrow \Sigma^0\overline{\Sigma}{}^0 $ and $ e^+e^-\rightarrow\Sigma^+\overline{\Sigma}{}^-$ are studied using initial-state-radiation events in a sample of 980 $\,\mbox{fb}^{-1}$ collected with the Belle detector at the KEKB asymmetric-energy $ e^+e^- $ collider. The cross sections from the mass threshold to $ 3{\mathrm{\,Ge\kern -0.1em V\!/}c^2} $ and the effective form factors of $ \Sigma^0 $ and $ \Sigma^+ $ are measured. In the charmonium region, we observe the decays $J/\psi\rightarrow\Sigma^0\overline{\Sigma}{}^0$ and $J/\psi\rightarrow\Sigma^+\overline{\Sigma}{}^-$ and determine the respective branching fractions.
Comment: accepted by Phys. Rev. D