  Using Luescher's method we determine the elastic scattering phases in the
broken phase of the 4-dimensional O(4) non-linear sigma-model from the
two-particle energy spectrum in a Monte-Carlo study on finite lattices. In the
isospin-0-channel we observe the sigma-resonance and extract its mass and its
width. In all scattering channels investigated the results are consistent with
perturbative calculations.
