  We study electronic structure of hole- and electron-doped Mott insulators in
the two-dimensional Hubbard model to reach a unified picture for the normal
state of cuprate high-Tc superconductors. By using a cluster extension of the
dynamical mean-field theory, we demonstrate that structure of coexisting zeros
and poles of the single-particle Green's function holds the key to understand
Mott physics in the underdoped region. We show evidence for the emergence of
non-Fermi-liquid phase caused by the topological quantum phase transition of
Fermi surface by analyzing low-energy charge dynamics. The spectra calculated
in a wide range of energy and momentum reproduce various anomalous properties
observed in experiments for the high-Tc cuprates. Our results reveal that the
pseudogap in hole-doped cuprates has a d-wave-like structure only below the
Fermi level, while it retains non-d-wave structure with a fully opened gap
above the Fermi energy even in the nodal direction due to a zero surface
extending over the entire Brillouin zone. In addition to the non-d-wave
pseudogap, the present comprehensive identifications of the spectral asymmetry
as to the Fermi energy, the Fermi arc, and the back-bending behavior of the
dispersion, waterfall, and low-energy kink, in agreement with the experimental
anomalies of the cuprates, do not support that these originate from (the
precursors of) symmetry breakings such as the preformed pairing and the
d-density wave fluctuations, but support that they are direct consequences of
the proximity to the Mott insulator. Several possible experiments are further
proposed to prove or disprove our zero mechanism.
