Renormalization in classical mechanics and many body quantum field theory (Q1333796)

We attempt to give a pedagogical introduction to perturbative renormalization. Our approach is first to describe, following Linstedt and Poincaré, the renormalization of formal perturbation expansions for quasi-periodic orbits in Hamiltonian mechanics. We then discuss the renormalization of the formal ground state energy density of a many fermion system. The construction of formal quasi-periodic orbits is carried out in detail to provide a relatively simple model for the considerably more involved, and perhaps less familiar, perturbative analysis of a field theory.