SCATTERING PHASES ON FINITE LATTICES IN THE BROKEN PHASE OF THE 4-DIMENSIONAL O(4).PHI(4) THEORY

According to a proposal of Luscher it is possible to determine elastic scattering phases in infinite volume from the energy spectrum of two- particle states in a periodic box. We demonstrate the applicability of this method in the broken phase of the four-dimensional O(4) non-line ar sigma-model in a Monte Carlo study on finite lattices. This nonpert urbative approach also permits the study of unstable particles, the si gma-particle in our case. We observe the sigma-resonance and extract i ts mass and width. In all scattering channels investigated the results are completely consistent with perturbative calculations.