Incoherent midinfrared charge excitation and the high-energy anomaly in the photoemission spectra of cuprates

On the basis of a semiphenomenological model, it is argued that the high-energy anomaly observed in recent photoemission experiments on cuprates is caused by interaction with an overdamped bosonic mode in the midinfrared region of the spectrum. Analysis of optical conductivity allows us to connect this excitation to the incoherent charge response reported for the majority of high-T-c materials and some other perovskites. We show that its large damping is an essential feature responsible for the "waterfall" dispersion and linewidth of the spectral weight.