THE EIGENVALUE SPECTRA IN Z(2)XZ(2) AND SU(2)XSU(2) FERMION-HIGGS MODELS

We present an analysis of the eigenvalue spectra of the Dirac operator M and related operators M' and MM in an SU(2) x SU(2) and a Z(2) x Z(2) fermion-Higgs model in the quenched approximation. We especially study the spectra in the symmetric and broken symmetry phases along the crossover line which was recently discovered in these models in numerical simulations. It turns out that in the symmetric phases of both models zero modes emerge along the crossover line. In the case of the Z(2) model the zero modes follow the crossover line into the broken symmetry phase whereas in the case of the SU(2) model they appear to stop at the phase transition line between the symmetric and the broken phases.