Theory of critical charge fluctuations and pseudogap formation in the single-band Hubbard model

Within a single-band Hubbard model, treated by means of a strong-coupling a pproach based on a cumulant expansion, we investigate the existence of crit ical charge fluctuations (CCF) that could give rise to a phase separation ( PS) or a charge density wave, by means of a Bethe-Salpeter equation for the vertex function in the particle-hole channel. We discuss the relevance of the precursor effects of charge ordering an the self-energy of the electron s and the non-Fermi liquid behavior arising from an effective electron-elec tron interaction.