Infrared Behavior of the Gluon Propagator in Lattice Landau Gauge

We evaluate numerically the four-momentum-space gluon propagator in lattice Landau gauge, for pure SU(2) lattice gauge theory with periodic boundary conditions. Simulations are done in the strong-coupling regime, namely at $\beta = 0, 0.8, 1.2 and 1.6$, and for lattice sizes up to $30^4, 16^4, 20^4 and 24^4$ respectively. In the limit of large lattice volume, we observe in all cases a gluon propagator decreasing as the momentum goes to zero. This counter-intuitive result has a straightforward interpretation as resulting from the proximity of the so-called first Gribov horizon in infrared directions.