Functional renormalization group approach to the four-body problem

Abstract

We present a renormalization group analysis of the non-relativistic four-boson problem by means of a simple model with pointlike three- and four-body interactions. We investigate in particular the unitarity point where the scattering length is infinite and all energies are at the atom threshold. We find that the four-body problem behaves truly universally, independent of any four-body parameter confirming the findings of Platter et al. and von Stecher et al. [1–3].