Dynamical nature of chaos in electron systems of high-$T_c$ superconductors

A model of the fermion-condensation phase transition forming a plateau in the spectrum of single-particle excitations near the Fermi surface at $T=0$ is used to analyze those features of the spectral functions of normal states of high-$T_c$ superconductors which are inherent in a marginal Fermi liquid contaminated by impurities. With this model, such a behavior is shown to be due to the fermion condensate, which acts as an impurity subsystem because its energy spectrum at $T=0$ is dispersionless. The influence of the anisotropy of condensate distribution in the Brillouin zone on the spectral functions is discussed.