Cluster and single-particle distributions in nucleus-nucleus interactions

Relativistic nuclear reactions, π- - C (pbeam = 40 GeV/c), Mg - Mg (pbeam = 4.5 A GeV/c), and C - C (pbeam = 4.2 A GeV/c), are compared by using Lorentz-invariant variables bik. These variables are used to compare and classify nuclear reactions of various types in a wide range of energies. Different algorithms of clusters separation in the four-velocity space are compared. Experimental distributions are analyzed by means of invariant variables in the space to understand the difference of behaviour of particles and clusters for these reactions. Universal properties of hadron clusters are presented