This book provides a systematic study of spectral and scattering theory  for many-body Schrödinger operators at two-cluster thresholds. While the  two-body problem (reduced after separation of the centre of mass motion to a one-body problem at zero energy) is a well-studied subject, the  literature on  many-body threshold problems  is sparse. However, the authors’ analysis covers for example the system of three particles  interacting by Coulomb potentials and restricted to a small energy  region to the right of a fixed nonzero two-body eigenvalue. In...