Perturbative Renormalization in Quantum Few-Body Problems

As in quantum field theory, for some singular two-body potentials, the momentum-space perturbative treatment of the three-dimensional quantum $N$-body problem is shown to exhibit ultraviolet divergences. Renormalization of these models leads to a scale and finite observables. For a Dirac delta potential we carry on this renormalization for two- and three-body systems. A new divergence, and hence a new scale, emerges for each added particle. For $N\ge 3$ there are no divergences in one and two dimensions. The physical implications of these results are discussed.