Three steps in intranuclear cascading

Between the initial excitation of nucleons by the passing throughout each other and the final cascading of newly created hadrons there should be considered one more step. We call it the second step cascading process. It acts as an interaction of wounded nucleon from one nucleus with another nucleon from the same nucleus. This mechanism leads to the significant increase on the inelasticity for nuclei collisions without changing the hadron–hadron interaction characteristics. The nucleus–nucleus interaction can be described quite successfully within the framework of wounded nucleon model. It can be expressed in the statement that once one of projectile nucleons interacts inelastically with the one from a target nucleus intermediate states called “wounded nucleons” are created. The spatial extension of the wounded nucleon is the same as original nucleon before the collision. The subsequent collisions inside the target nucleus take place before this “excited state” hadronize. The detailed insight into the intranuclear collisions process gave a surprising result which lead to the revision of, e.g., the conventional interpretation of connections between inelasticity in nuclei and hadronic collisions and respective cross section ratios [1]. In the wounded nucleons picture of the high-energy nucleus–nucleus interaction the non-zero time interval between excitation and hadronization leads to the possibility which we will call hereafter second step cascading: the interaction of wounded nucleon from one (target or projectile) nucleus with another nucleon from the same nucleus before the hadronization occurs. The great influence of second step cascading process is straightforward. On the projectile side (high laboratory energy) the excitation of one initially untouched nucleons by a excited state going backward in anti-laboratory frame of reference leads to transfer a part of nucleon energy to the secondary produced particles. Their energy in the nucleus center of mass system are rather small but after transformation to the laboratory system the effect is expected to be quite considerable. Results presented in the present paper are obtained using the geometrical chain model. Recently [2] the geometrical multichain (GMC) extension to very high energies of the geometrical two-chain model [3] has been presented. Obtained proton–proton multiparticle production characteristics show that up to at least SPS energies the underlying physics can be treated as competitive to that used by Dual Parton-like models or relativistic jet (LUND-like) idea. The GMC model of the nucleon–nucleon (hadron–hadron) collision differs from the others (DPMor LUND-type models) in a details of the treatment of the creation of “wounded nucleons” (excited states, chains, strings). In the GMC model a phenomenological description of the chain creation is used with a very few parameters to be adjusted directly to the soft hadronic interaction data, instead of using