Quantum Zeno Paradox and Dynamics of Systems at Short Time Scales

The short-time dynamics of quantum systems is investigated in the context of quantum Zeno effect. Nonlocality of the electromagnetic interaction, which in describing the quantities associated with the $S$-matrix is hidden in the regularization and renormalization procedures, is stated to manifest itself explicitly in processes at extremely short time scales. This results in the fact that the quantum Zeno effect does not take place in the radiative decay of an unstable atomic state.