ИСТИНА

The calculation of the complete one-loop electroweak radiative correction for the process \( l^{+} l^{-} \to \gamma\gamma \) is presented. The calculations are performed using the {\tt SANC} system. One-loop calculations were carried out with keeping the masses in the initial state, i.e. performed in massive basis. The helicity amplitudes approach is used for all contributions. Good agreement reached with results existing in the world literature, i.e. at tree level with {\tt CalcHEP}, {\tt WHIZARD} and at one-loop level with {\tt BabaYaga$@$NLO}. The work can be useful at $e^+e^-$ accelerators of both low and high energies.