Gluon propagator in the infrared region

The gluon propagator is calculated in quenched QCD for two different lattice sizes (${16}^3\times 48$ and ${32}^3\times 64$) at $\beta =\mathrm{6.0.}\mathrm{}$ The volume dependence of the propagator in the Landau gauge is studied. The smaller lattice is instrumental in revealing finite volume and anisotropic lattice artifacts. Methods for minimizing these artifacts are developed and applied to the larger lattice data. New structure seen in the infrared region survives these conservative cuts to the lattice data. This structure serves to rule out a number of models that have appeared in the literature. A fit to a simple analytical form capturing the momentum dependence of the nonperturbative gluon propagator is also reported.