Theory of normal state single particle and transport properties

In the framework of a scenario consisting of a mixture of itinerant electrons and localized bipolarons, hybridized with each other via a charge exchange term, we discuss the evolution of certain physical features of the pseudogap phase as the temperature decreases from T ∗ to T c . This evolution can be characterized by the presence of purely diffusive electron-pairs just below T ∗ , their becoming itinerant below a certain temperature T B ∗ and their ultimate condensation into a superconducting state at T c . An onset of a Drude component in the optical conductivity and imperfect Meissner screening in the temperature interval [ T c, T B ∗ ] are manifestations of that.