NONPERTURBATIVE MATCHING FOR FIELD-THEORIES WITH HEAVY FERMIONS

We examine a paradox, suggested by Banks and Dabholkar, concerning non perturbative effects in an effective field theory which is obtained by integrating out a generation of heavy fermions, where the heavy fermi on masses arise from Yukawa couplings. They argue that light fermions in the effective theory appear to decay via instanton processes, where as their decay is forbidden in the full theory. We resolve this parado x by showing that such processes in fact do not occur in the effective theory, due to matching corrections which cause the relevant light fi eld configurations to have infinite action.