Exact dynamical structure factor of the degenerate Haldane-Shastry model

The dynamical structure factor S(q,omega) of the K-component (K = 2, 3, 4) spin chain with a 1/r(2) interaction is derived exactly at zero temperature for the arbitrary size of the system. The result is interpreted in terms o f a free quasiparticle picture which is a generalization of the spinon pict ure in the SU(2) case. The excited states consist of K quasiparticles each of which is characterized by a set of K - 1 quantum numbers. Divergent sing ularities of S(q, omega) at the spectral edges are derived analytically. Th e analytic result is checked numerically for finite systems.