Particle production from axial fields - art. no. 063501

We study the production of massive fermions in arbitrary vector and axial-v ector classical backgrounds using effective action techniques. A perturbati ve calculation shows the different features of each field and in particular it is seen that pure temporal axial fields can produce particles whereas i t is not possible for a pure vector background. We also analyze from a non- perturbative point of view a particular configuration with constant electri c and axial fields and show that the presence of the axial background inhib its the production from the electric field. [S0556-2821(99)04504-X].