Numerical investigation of the four-dimensional nonlinear sigma-model

Results from a numerical simulation of the four-dimensional O(4)-symmetric Φ4-model in the phase with unbroken symmetry at infinite bare quartic coupling are presented. Using a recently developed efficient cluster updating algorithm the renormalized mass and coupling are determined with high precision. Finite size effects are studied with special care in order to achieve a reliable infinite volume extrapolation. The finite volume behaviour of masses and couplings is well approximated by one-loop renormalized perturbation theory. The obtained infinite volume results agree with a recent analytical calculation based on a high order hopping parameter expansion. (orig.)