Computation of dynamical correlation functions of Heisenberg chains in a field

TL;DR

This paper calculates the dynamical spin structure factor for a 1D Heisenberg chain in a magnetic field using exact form factors, providing detailed numerical results that satisfy sum rules with high accuracy.

Contribution

It introduces a method to compute multiparticle contributions to the dynamical structure factor of the Heisenberg chain using exact determinant form factors.

Findings

High-precision saturation of the sum rule achieved

Detailed momentum- and frequency-dependent structure factors obtained

Numerical results applicable across the entire Brillouin zone

Abstract

We compute the momentum- and frequency-dependent longitudinal spin structure factor for the one-dimensional spin-1/2 $XXZ$ Heisenberg spin chain in a magnetic field, using exact determinant representations for form factors on the lattice. Multiparticle contributions are computed numerically throughout the Brillouin zone, yielding saturation of the sum rule to high precision.