Bare electron dispersion from experiment: Self-consistent self-energy analysis of photoemission data

Performing an in-depth analysis of the photoemission spectra along the nodal direction of the high-temperature superconductor Bi-2212 we developed a procedure to determine the underlying electronic structure and established a precise relation of the measured quantities to the real and imaginary parts of the self-energy of electronic excitations. The self-consistency of the procedure with respect to the Kramers-Kronig transformation allows us to draw conclusions on the applicability of the spectral function analysis and on the existence of well-defined quasiparticles along the nodal direction even for the underdoped Bi-2212 in the pseudogap state. The analysis of the real part of the self-energy Σ^'(ω) for an overdoped and underdoped Bi-2212 helps to distinguish the 700.3em0exmeV ``kink'' from Σ^'(ω) maximum and conclude about doping dependence of the kink strength.