W-pair production in modified perturbation theory

We examine capabilities of the modified perturbation theory (MPT) for description of the processes with productions and decays of fundamental unstable particles. We calculate total cross-section for $e^{+} e^{-} \to \gamma,Z \to W^{+} W^{-} \to 4f$ in a model with the Dyson-resummed and with the MPT-expanded up to the NNLO Breit-Wigner factors, and compare the outcomes. At the ILC energies a coincidence of the outcomes is detected with precision better than one per-mille.