Determination of the branching fractions for $\psi(3770) \to D^0 \bar   D^0, D^+D^-,D\bar D$ and $\psi(3770) \to {\rm non-}D\bar D$
  The branching fractions for $\psi(3770) \to D^0 \bar D^0, D^+D^-,D\bar D$ and $\psi(3770) \to {\rm non-}D\bar D$ are determined based on the cross sections for $\psi(3770)$ and $D \bar D$ production measured by BES Collaboration. From its recent publications we determine the branching fractions for $\psi(3770) \to D^0 \bar D^0, D^+D^-$ and $\psi(3770) \to D\bar D$ to be $(52.2\pm 4.8\pm 5.5)%$, $(37.0 \pm 5.0 \pm 4.3)%$ and $(89.1 \pm 6.9 \pm 9.2)%$, respectively. The latter one implies the branching fraction for $\psi(3770) \to {\rm non-}D\bar D$ to be $(10.9 \pm 6.9 \pm 9.2)%$, corresponding the inclusive ${\rm non-}D \bar D$ partial width $\Gamma(\psi(3770) \to {\rm non-}D\bar D) = (2.8 \pm 1.8 \pm 2.4)$ MeV. Meanwhile we determine the observed cross section for $non-D\bar D$ event production from $\psi(3770)$ decays to be $\sigma^{\rm obs}(\psi(3770)\to non-D\bar D) = (0.72 \pm 0.46 \pm 0.62)$ nb. 
G. Rong, D.H. Zhang and J.C. Chen