arXiv:cond-mat/9912244 · Physical Review Letters
Exact Dynamical Structure Factor of the Degenerate Haldane-Shastry Model
Takashi Yamamoto, Yasuhiro Saiga, Mitsuhiro Arikawa, Yoshio Kuramoto
Abstract
The dynamical structure factor $S(q,\ensuremath{\omega})$ of the $K$-component ( $K\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}2$, $3$, $4$) 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 of a free quasiparticle picture which is a generalization of the spinon picture in the $\mathrm{SU}(2)$ case. The excited states consist of $K$ quasiparticles each of which is characterized by a set of $K\ensuremath{-}1$ quantum numbers. Divergent singularities of $S(q,\ensuremath{\omega})$ at the spectral edges are derived analytically. The analytic result is checked numerically for finite systems.