In the framework of the Standard Model we present new theoretical predictions for the branching ratios, double and single differential distributions and forward—backward leptonic asymmetries for the decay. In our consideration we take into account the —resonance contribution; the main contributions of four charmonium resonances : and —resonant contribution from and ‘tails’ contributions from and resonances; non—resonant contribution of the - pairs, bremsstrahlung and the contribution of the weak annihilation. We provide the prediction for the branching ratio of decay with and without the —resonance contribution. We use the model of vector meson dominance (VMD) for calculation of resonances contributions and take into account all substantive terms in amplitude that was not considered in the previously papers.