Electromagnetic effects in resonant processes on colliding beams

The way to take into account electromagnetic effects, arising in the processes with heavy narrow resonance production in e+e- annihilation has been considered in the present paper. The method is based on low energy theorem, unitarity and dispersion relations. Formulae for total cross section of resonance production and cross section of two-particle channels have been obtained with account of radiation processes. (For the latter one radiative corrections take place in the interference term of the cross section). Universality of electromagnetic corrections in the cross sections for other channels is discussed. Formulae for the width of resonance decay into a leptonic pair and photon have been derived for different experimental conditions