title: Computation of dynamical correlation functions of heisenberg chains in a magnetic field.
abstract: We compute the momentum- and frequency-dependent longitudinal spin structure factor for the spin-1/2 XXZ Heisenberg spin chain in a magnetic field, using exact determinant representations for form factors on the lattice. Multiparticle (i.e., multispinon) contributions are computed numerically throughout the Brillouin zone, yielding saturation of the sum rule to high precision.
authors.affiliation: Institute for Theoretical Physics, University of Amsterdam, The Netherlands.
authors.forename: Jean-Sébastien
authors.initials: JS
authors.lastname: Caux
authors.forename: Jean Michel
authors.initials: JM
authors.lastname: Maillet