Poisson Formula for Resonances in Even Dimensions

We consider scattering by an abstract compactly supported perturbation in R^n. To include the traditional cases of potential, obstacle and metric scattering without going into their particular nature we adopt the "black box" formalism developed jointly with Sjostrand [23]. It is quite likely that one could extend the results presented here to the case of non-compactly supported perturbation as well - see [21] for a natural generalization of "black box" perturbations.