On the "Field-Theoretical Approach" to the Neutron-Antineutron Oscillations in Nuclei

It is argued that within the correct treatment of analytical properties of the transition amplitudes, in particular, the second order pole structure, characteristic for the $n - \bar n$ transition in nuclei, the "infrared divergences" discussed in some papers, do not appear. Explicit calculation with the help of diagram technique shows that the neutron-antineutron oscillations are strongly suppressed within a deuteron, as well as within arbitrary nucleus, in comparison with the oscillations in vacuum.