Study of the decoupling of heavy fermions in a Z2 scalar-fermion model

According to one-loop perturbation theory, fermions whose masses are totally generated from Yukawa couplings do not decouple in the heavy mass limit. We investigate this issue nonperturbatively in a four-dimensional Z2 scalar-fermion model with staggered fermions. Our data at intermediate and stronger Yukawa couplings on 84 and 124 lattices suggest the nondecoupling of heavy fermions as predicted from the one-loop calculation. However, at the strongest Yukawa coupling where a possible multi-critical point may come into play, we cannot be conclusive.