The three-boson system with short-range interactions

We discuss renormalization of the non-relativistic three-body problem with short-range forces. The problem is non-perturbative at momenta of the order of the inverse of the two-body scattering length. An infinite number of gr aphs must be summed, which leads to a cutoff dependence that does not appea r in any order in perturbation theory, We argue that this cutoff dependence can be absorbed in one local three-body force counterterm and compute the running of the three-body force with the cutoff. This allows a calculation of the scattering of a particle and the two-particle bound state if the cor responding scattering length is used as input. We also obtain a model-indep endent relation between binding energy of a shallow three-body bound state and this scattering length. We comment on the power counting that organizes higher-order corrections and on relevance of this result for the effective field theory program in nuclear and molecular physics. (C) 1999 Elsevier S cience B.V.