  Evolution of the hole spectral function along the Gamma-(pi,pi) cut is
studied in the antiferromagnetic state of the Hubbard model. The kink in the
calculated hole dispersion, the sharp spectral-weight transfer between the
branches, and the drastically suppressed coherent spectral weight near k=(0,0),
as observed recently in the high-resolution ARPES studies of cuprate
antiferromagnets, are shown to be strongly enhanced by finite-U
double-occupancy effects. Together with the anomalous spin-wave dispersion
observed earlier in high-resolution neutron-scattering studies, the present
study provides further evidence of a unified description of magnetic and
electronic excitations in cuprate antiferromagnets in terms of the Hubbard
model.
