Metal-insulator crossover in the Boson-Fermion model in infinite   dimensions
  The Boson-Fermion model, describing a mixture of tightly bound electron pairs and quasi-free electrons hybridized with each other via a charge exchange term, is studied in the limit of infinite dimensions, using the Non-Crossing Approximation within the Dynamical Mean Field Theory. It is shown that a metal-insulator crossover, driven by strong pair fluctuations, takes place as the temperature is lowered. It manifests itself in the opening of a pseudogap in the electron density of states, accompanied by a corresponding effect in the optical and dc conductivity. 
J.-M. Robin (1), A. Romano (2) and J. Ranninger (3) ((1) Max Planck   Institut, Dresden, Germany, (2) Universita' di Salerno...