Interaction of a light particle with a system of heavy particles
Kirzhnits D. A., Pen'kov F. M.
When a light particle interacts with a bound complex, the decay over distance is described by a 1/r2 law instead of 1/r4 law. The corresponding force is unusual in several respects: It is proportional to the mass of the particle; it acts only in the s state of the particle; it generates a series of bound states similar to Efimov levels, etc.