Effects of Coulomb Interactions Between Fermions on Superconductivity in Boson-Fermion Model

Influence of Coulomb repulsion between fermions on stability of the superconducting state in the model of boson-like local electron pairs hybridized with wide-band fermions is studied. It is shown rigorously that the Bose condensation of the local pairs implies a divergence of the pairing susceptibility in the fermion subsystem. Charge carrier concentration dependence of the critical temperature T$\text{}_{c}$ is evaluated with the help of random phase approximation and spectral properties of the bosons at T$\text{}_{c}$ are analyzed