The standard approach to determine the parameters of a resonance is based on the study of the volume dependence of the energy spectrum. In this work we study a non-linear sigma model coupled to a scalar field in which a resonance emerges. Using an an
alysis method introduced recently, based on the concept of probability distribution, it is possible to determine the mass and the width of the resonance.
Monte Carlo simulations of the 4d O(4) model in the broken phase are performed to determine the parameters of a resonance. The standard method for extracting them on the lattice is through Luschers formula; recently a new method, based on the probabi
lity distribution concept, has been proposed. We study the application of these methods and compare them with Monte Carlo data.
