Fermi arcs as a visible manifestation of pair level of negative-U centers

Here we consider the possibility that the Fermi arcs observed in ARPES experiments result from interaction of valence band electrons with negative-U centers (NUCs) which are formed under doping on the pairs of neighboring Cu cations in CuO2 plane. This interaction results in two-particle hybridization and vanishing of the gap over the part of Fermi contour. Furthermore the transitions of electrons to NUCs result in the generation of free hole carriers. Just these carriers rather than doping induced charges provide conduction in the normal state.