A systematic study of the low energy effects of heavy particles in the standard model

In this approach, at any loop order, the low energy effects of a heavy Higgs boson and a heavy fermion can be summarized by an effective lagrangian. To the one-loop order, an effective lagrangian for the bosonic sector of the theory is constructed. One fermion mass is light (m) and the other is heavy (M). At the one-loop level heavy fermion mass effects proportional to M²and ln(M/m) have been found. It is shown here that in the presence of gauge fields, the infinites 1/ε{lunate} of the nonlinear σ-model do not fully reproduce the ln(M_H) of the linear σ-model.