The SU(ν) generalized Haldane-Shastry spin chain with 1/r2 interaction
is studied with twisted boundary conditions. The exact wavefunctions of Jastrow
type are obtained for every rational value of the twist angle in unit of
2π. The spectral flow of the ground state is then discussed as a function
of the twist angle. By resorting to the motif picture in the Bethe ansatz
method, we show that the period of the spectral flow is ν, which is
determined by the statistical interaction in exclusion statistics.Comment: 23 pages, revtex, To appear in Nucl. Phys.