Multiparticle production in high-energy hadron-nucleus collisions

An attempt is made to understand the gross features of multiparticle production in high-energy hadron-nucleus collisions (including the nuclear-size dependence of inclusive cross sections at large transverse momenta and the energy and atomic-number dependence of average multiplicity) in terms of a simple physical picture. The main characteristics of this picture are: (a) The time needed for the formation of multibody final states in hadron-hadron collisions at high energies is so long that in a high-energy hadron-nucleus multiparticle-production process the nucleons along the path of the incident hadron inside the target nucleus can be viewed as acting collectively, and in the first-order approximation can be considered as a single object—an "effective target." (b) This hadron-effective-target collision process can be described by the same physical picture as that used to describe the collision between two hadrons. In particular, such a collision is either gentle (fragmentation) or violent (violent collision). (c) The mass of the effective target is proportional to its "average thickness." For the sake of simplicity and definiteness, the ansatz $M = A^{\frac{1}{3}}{M}_1$ (here $A$ is the atomic mass number of the nucleus, $M$ and $M_1$ are the mass of the effective target and that of the proton, respectively) is used to carry out the illustrative examples. Arguments for this picture are presented. Further experiments are suggested.