Date of Original Version
In a recent publication /1/ we found that the T=o dynamics of the 1D s=1/2 Heisenberg antiferromagnet (HB AF) with nearest-neighbor exchange interaction J is almost completely dominated by a particular continuum of excitations (called spin-wave continuum, SWC) bounded by the dispersion branches ε1(q) = (πJ/2)sinq and ε2(q)=πJsin(q/2). It differs markedly from the classical 1D HB AF where the spectral weight is concentrated on a single branch of spin-waves. The result for the structure function Sμμ(q,ω)≡⟨SulSul⟩q,ω which is a special case of Eq.(6), is in good agreement with low-T neutron scattering data on CPC /2/ concerning excitation energies, lineshapes and integrated intensity.
Gerhard Müller, Harry Thomas, Marcos W. Puga and Hans Beck. Quantum effects in the dynamics of the one-dimensional planar antiferromagnet, in Physics in one dimension, J. Bernasconi and T. Schneider (Eds.), Springer Series in Solid State Sciences (Springer, Berlin-Heidelberg-New York, 1981), pp. 165-168.