Zero-Temperature Dynamics of theS=12Linear Heisenberg Antiferromagnet

Abstract

We present an analytical expression for the dynamical spin-correlation function of the $S=\frac{1}{2}$ linear Heisenberg antiferromagnet based on the fact that the spectrum is dominated by a double continuum of spin-wave excitations. Our expression is not exact, but exact sum rules show that the degree of approximation is small. We predict that in a uniform magnetic field the spectral weight function will display a double-peaked structure. Such a feature is observed in recent neutron-scattering experiments.