Normal state pseudogap and (π, 0) feature in the underdoped high-Tc cuprates:: A microscopic theory

We show that the pseudogap phenomenon observed in the underdoped cuprates, including such details as the increase of pseudogap with decreasing doping delta, its T independence, its closing at temperature T-gap* which grows with decreasing delta, the gradual destruction of the Fermi surface with decreasing T starting from T-gap(*), the anomalous form of electron spectral functions as functions of energy, and the form of wave-vector dependence of the "spectrum" around (0, pi), can be naturally understood within a concept of proximity of the underdoped regime to a 2D electronic topological transition.