Effects of electroweak radiative corrections in polarized low-energy electron-positron annihilation into lepton pairs

Complete one-loop electroweak radiative corrections to the cross section of the process $e^{+}{e}^{-}\to {\mu }^{-}{\mu }^{+}({\tau }^{-}{\tau }^{+})$ are evaluated with the help of the \SANC system. Higher-order contributions of the initial state radiation are computed in the QED structure function formalism. Numerical results are given for the center-of-mass energy range $\sqrt{s}=5,7$~GeV for various polarization degrees of the initial particles.