Absorption in the final state in reactions and decays in the medium

Abstract

The role of strong absorption of particles in intermidiate and final states has been considered. The range of applicability of phenomenological model of absorption has been studied. This model is nonuniversal. Its applicability depends on the type of interaction Hamiltonian and matrix element used. We also demonstrate that the violation of the unitarity condition can produce a qualitative error in the results. The absorption (decay) in the final state does not tend to suppress the total process probability as well as the probability of the channel corresponding to absorption. This is true for the reactions, decays and $n\bar{n}$ conversion in the medium.