Bound states in kinetic theory

Therefore, the condition of complete weakening of the initial correlations corresponds to the assumption that the long-living correlations (with TCOrr 5 Trej) do not play an essential role. We shall see later, especially in connection with the problem of bound states in kinetic theory, that this is not always ture. 

In order to discuss the fundamental problems that are connected with the bound states in kinetic theory, we first restrict ourselves to systems with two-particle bound states only. The states of the two-particle system are determined by Eq. (2.12). Furthermore, we remark that to describe the formation of two-particle bound states by a collision, at least three particles are necessary in order to fulfill energy and momentum conservation. Thus, it is necessary to consider the quantum mechanics of three-particle systems. 

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