  We analyze enhancements in the magnitude of the self-energy for electrons far
away from the Fermi surface in doped Mott insulators using the dynamical
cluster approximation to the Hubbard model. For large onsite repulsion, U, and
hole doping, the magnitude of the self-energy for imaginary frequencies at the
top of the band (k=(pi,pi) is enhanced with respect to the self-energy
magnitude at the bottom of the band (k=(0,0)). The self-energy behavior at
these two k-points is switched for electron doping. Although the hybridization
is much larger for (0,0) than for (pi,pi), we demonstrate that this is not the
origin of this difference. Isolated clusters under a downward shift of the
chemical potential, mu<U/2, at half-filling reproduce the overall self-energy
behavior at (0,0) and (pi,pi) found in low hole doped embedded clusters. This
happens although there is no change in the electronic structure of the isolated
clusters. Our analysis shows that a downward shift of the chemical potential
which weakly hole dopes the Mott insulator can lead to a large enhancement of
the (pi,pi) self-energy which is not necessarily associated with electronic
correlation effects, even in embedded clusters.
