A scalar-fermion model in the limit of infinitely heavy fermions

As a first step in the non-perturbative study of a chiralU(1)⊗U(1) Yukawa-model with explicit mirror fermions the limit of infinite bare fermion mass is considered. Non-perturbative information is obtained from 14th order scalar hopping parameter expansion, which is confronted with high statistics numerical data. A remarkable universality of the upper bound for the renormalized quartic coupling is observed. A new kind of first order phase transition surface is localized, which is characterized by a large jump in the average field length