Measurements of the cross sections for $e^{+}{e}^{-}\to \mathrm{hadrons}$ at 3.650, 3.6648, 3.773 GeV and the branching fraction for $\psi (3770)\to \mathrm{non}-D\bar{D}$

M. Ablikim et al.

Using the BES-II detector at the BEPC Collider, we measured the lowest order cross sections and the $R$ values ($R={\sigma }_{e^{+}{e}^{-}\to \mathrm{hadrons}}^0/{\sigma }_{e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}}^0$) for incl…