  Using variational cluster perturbation theory we study the competition
between d-wave superconductivity (dSC) and antiferromagnetism (AF) in the the
t-t'-t''-U Hubbard model. Large scale computer calculations reproduce the
overall ground state phase diagram of the high-temperature superconductors as
well as the one-particle excitation spectra for both hole- and electron-doping.
We identify clear signatures of the Mott gap as well as of AF and of dSC that
should be observable in photoemission experiments.
