Boundary critical phenomena inSU(3) `spin' chains

Abstract

SU(3)-invariant `spin' chains with a single impurity, such as a modified exchange coupling on one link, are analysed using boundary conformal field theory techniques. These chains are equivalent to a special case of the `tJV' model, i.e. the tJ model with a nearest-neighbour repulsion added. In the continuum limit they are equivalent to two free bosons at a special value of the compactification radii. The SU(3) symmetry, which is made explicit in this formulation, provides insight into the exact solution of a non-trivial boundary critical point found earlier in another formulation of this model as a theory of quantum Brownian motion.