Non-Linear Effects in High Energy Hadronic Interactions
  The influence of non-linear interaction effects on the characteristics of hadronic collisions and on the development of extensive air showers (EAS) is investigated. Hadronic interactions are treated phenomenologically in the framework of Gribov's Reggeon approach with non-linear corrections being described by enhanced (Pomeron-Pomeron interaction) diagrams. A re-summation algorithm for higher order enhanced graphs is proposed. The approach is applied to develop a new hadronic interaction model QGSJET-II, treating non-linear effects explicitely in individual hadronic and nuclear collisions. The model is applied to EAS modelization and the obtained results are compared to the original QGSJET predictions. Possible consequences for EAS data interpretation are discussed. 
S. Ostapchenko