  We investigate the SU(N) Principal Chiral Model on a half-line with a
particular set of boundary conditions (BCs). In previous work these BCs have
been shown to correspond to boundary scattering matrices (K-matrices) which are
representation conjugating and whose matrix structure corresponds to one of the
symmetric spaces SU(N)/SO(N) or SU(N)/Sp(N). Starting from the bulk particle
spectrum and the K-matrix for a particle in the vector representation we
construct K-matrices for particles in higher rank representations scattering
off the boundary. We then perform an analysis of the physical strip pole
structure and provide a complete set of boundary Coleman-Thun mechanisms for
those poles which do not correspond to particles coupling to the boundary. We
find that the model has no non-trivial boundary states.
