The Landau gauge gluon propagator: Gribov problem and finite-size effects

The SU(2) gluon propagator in Landau gauge is studied on the lattice. Our gauge fixing procedure employs simulated annealing and Z(2)-flips. It finds higher maxima of the gauge functional compared with those obtained with the standard overrelaxation and leads to systematic deviations of the gluon propagator in the infrared region. In particular, finite-size effects for lattice sizes from (1.7 fm)^4 up to (6.5 fm)^4 become weak. The propagator shows a plateau at p \approx 300 MeV.