Lorentz gauge fixing and lattice QED

The Gribov ambiguity problem is studied for compact lattice QED within the Lorentz gauge. In the Coulomb phase, Gribov copies are mainly caused by double Dirac sheets and zero-momentum modes of the gauge fields. Removing them by (non-) periodic gauge transformations allows to reach the absolute extremum of the Lorentz gauge functional. For standard Lorentz gauge fixing the Wilson fermion correlator turns out to be strongly effected by the zero-momentum modes. A reliable fermion mass estimate requires the proper treatment of these modes.