a Institut für Theoretische Physik, Universität Zürich, Winterthurerstr. 190, CH-8057, Zürich, Switzerland
Abstract:
The free energy density of the two-dimensional O(3) non-linear σ-model is calculated at finite temperature and finite spatial extent. Both an analytic calculation in the perturbative regime and a Monte Carlo study at low temperatures are presented. It is shown that using the fixed-point action instead of the standard Wilson action leads to a substantial reduction of the cut-off effects.