π-absorption by nucleon clusters

In this paper the experimental data which may indicate absorption of stopped φ- on α-clusters are discussed and arguments are given to show that ∼25% of φ- absorptions are of this kind. In the case of two-nucleon absorptions, the experimental information concerning the value of the ratio R between the numbers of n-p and p-p absorbing pairs (which critically depends both on the absorption mechanism and the short range nucleon-nucleon correlation) is discussed