Within the spin fermion model we introduce a minimal polaron picture from which the dispersion relations of the doped ${\mathrm{CuO}}_2$ planes are derived as a function of doping. A simple scenario shows up which incorporates an extended singularity in the density of states at the Fermi level up to some doping of order 0.2.

DOI:https://doi.org/10.1103/PhysRevB.55.14614