EXCITATION SPECTRUM AND CORRELATION-FUNCTIONS OF THE Z(3) CHIRAL POTTS QUANTUM SPIN CHAIN

We study the excitation spectrum and the correlation functions of the Z(3) chiral Potts model in the massive high-temperature phase using pe rturbation expansions and numerical diagonalization, We are mainly int erested in results for general chiral angles but we consider also the superintegrable case, For the parameter values considered, we find tha t the band structure of the low-lying part of the excitation spectrum has the form expected from a quasiparticle picture with two fundamenta l particles. Studying the chain-size dependence of the spectrum, we fi nd a remarkable stability of the second fundamental particle in a limi ted range of the momentum, even when its energy becomes so hi,oh that it lies very high up among the multiparticle scattering states, This i s not a phenomenon restricted to the superintegrable line. Calculating a non-translationally invariant correlation function, we give evidenc e that it is oscillating Within our numerical accuracy we find a relat ion between the oscillation length and the dip position of the momentu m dispersion of the lightest particle which seems to be quite independ ent of the chiral angles.