Pseudogap effects induced by resonant pair scattering

We demonstrate how resonant pair scattering of correlated electrons above T_c can give rise to pseudogap behavior. This resonance in the scattering T matrix appears for superconducting interactions of intermediate strength, within the framework of a simple fermionic model. It is associated with a splitting of the single peak in the spectral function into a pair of peaks separated by an energy gap. Our physical picture is contrasted with that derived from other T-matrix schemes, with superconducting fluctuation effects, and with preformed pair (boson-fermion) models. Implications for photoemission and tunneling experiments in the cuprates are discussed.