Chiral invariant phase space event generator

The Geant4 quark level CHIPS (CHiral Invariant Phase Space) model simulates nuclear reactions assuming asymptotic freedom of massless quarks uniformly distributed over invariant phase space. Electro-nuclear reactions are simulated generating low-Q² equivalent photons. In this paper generalisation of the model for high Q² is made to describe neutrino-nuclear reactions, where the low-Q² contribution is suppressed by the W -boson mass. The proposed non-perturbative approximation of structure functions fits high-energy lepto-nucleon reactions with high-Q² and neutrino-nucleon reactions starting from the threshold.