Distribution function of fusion reaction products and entropy evolution

One of the outcomes of nuclear reactions is that reaction products have at birth distribution functions far from Maxwellian. What role do those distribution functions play in the evolution of the entropy of the system? The purpose of this work is to show the effect of the distribution functions of reactant and reaction products on the entropy of a system undergoing DD nuclear fusion reactions. This analysis is conducted with the help of the H-theorem, in the framework of kinetic theory. It will be found that at the onset of this reaction, generalized system entropy decreases markedly.