Hadron Interactions–hadron Sizes

Hadronic interactions are successfully parameterized in different models. Those most frequently applied are the Regge parameterization and the geometrical model. In the present paper we want to apply the geometrical picture to different domains of the hadronic interaction. The model used is a very economical model in that it contains only few parameters most of which have a direct physical interpretation. We first want to apply the geometrical model to hadron–proton interactions. Then we want to extend the model to deep inelastic scattering. In deep inelastic scattering at small x, the interaction can be viewed upon as an interaction of the hadronic fluctuation of the photon with the proton. The size of the hadronic fluctuation is 〈r2〉 ≈ 1/Q. Thus, deep inelastic scattering offers a nice extension of the applicability of the geometrical model for hadronic sizes from 1 fm down to 10 fm. However, the nuclear shadowing demonstrates that in addition to the “hard” interaction corresponding to a hadronic size of 1/Q, an additional, “soft” component (large size) of the interaction in deep inelastic scattering is present. We will elaborate this in the section on nuclear structure function. We will point out the importance of these results for the theoretical treatment of the heavy ion reactions at high energies.