High-energy anomalies in covalent high-Tc cuprates with large Hubbard Ud on copper

A large Ud theory is constructed for the metallic state of high-Tc cuprates. The Emery three-band model, extended with Ox–Oy hopping tpp, and with Ud→∞Ud→∞, is mapped on slave fermions. The Dyson time-dependent diagrammatic theory in terms of the Cu–O hopping tpd, starting from the nondegenerate unperturbed ground state, is translationally and asymptotically locally gauge invariant. The small parameter of the theory is the average hole occupation of Cu sites nd. The lowest order of the theory generates the single particle propagators of the hybridized pdp- and dpd-fermions with the exact covalent three band structure. The leading many-body effect is band narrowing, accompanied by Landau-like damping of the single particle propagation, due to incoherent local charge Cu–O fluctuations. The corresponding continuum is found below and above the Fermi level.