Resonances within nonperturbative methods in field theories

We study the stability of solitonlike solutions of a classical relativistic field theory with logarithmic nonlinearities. For a given charge (not greater than a certain value $q_{max}$) the model exhibits a stable state and an unstable one. The latter state, instead of being nonphysical, can be interpreted as a resonance. Problems related to the semiclassical quantization of this theory are also discussed. All calculations are done in any number of spatial dimensions.