  We study the electronic structure of the doped paramagnetic insulator by
finite temperature Quantum Monte-Carlo simulations for the 2D Hubbard model.
Throughout we use the moderately high temperature T=0.33t, where the spin
correlation length has dropped to < 1.5 lattice spacings, and study the
evolution of the band structure with hole doping. The effect of doping can be
best described as a rigid shift of the chemical potential into the lower
Hubbard band, accompanied by some transfer of spectral weight. For hole dopings
<20% the Luttinger theorem is violated, and the Fermi surface volume, inferred
from the Fermi level crossings of the `quasiparticle band', shows a similar
topology and doping dependence as predicted by the Hubbard I and related
approximations.
