Hadronic shower models in GEANT4 - the frameworks

Optimal exploitation of hadronic final states played a key role in successes of all recent collider experiment in HEP, and the ability to use hadronic final states will continue to be one of the decisive issues during the analysis phase of the LHC experiments. Monte Carlo programs like GEANT4 (1994) facilitate the use of hadronic final states, and have been developed for many years. We give an overview of the Object Oriented frameworks for hadronic generators in GEANT4, and illustrate the physics models underlying hadronic shower simulation on examples, including the three basic types of modeling; data driven, parametrization driven, and theory driven modeling, and their possible realizations in the Object Oriented component system of GEANT4. We put particular focus on the level of extendibility that can and has been achieved by our Russian dolls approach to Object Oriented design, and the role and importance of the frameworks in a component system. (C) 2001 Elsevier Science B.V. All rights reserved.