  The method of factorization, based on the model of unstable particles with a
smeared mass, is applied to the processes with an unstable particle in the
intermediate state. It was shown, that in the framework of the method
suggested, the decay rate and cross-section can be represented in the universal
factorized form for an arbitrary set of particles. An exact factorization is
caused by the specific structure of unstable particles propagators. We
performed the phenomenological analysis of the factorization effect.
