Gluon Propagator in the Landau Gauge fixed Lattice QCD Simulation

We measured the gluon propagator in the Landau gauge fixed QCD Langevin simulation and studied the infra-red behaviour of the gluon propagator. The 4^3 x 8 lattice simulation was done for quenched $\beta=3,4,5$ and unquenched $\beta=4, \kappa=0.1,0.15,0.2$ using each 100 independent samples. The Landau gauge fixing was done by an extension of the Fourier acceleration method with the condition Max|div A|<10^{-4}, and the field A is related to the link variable by U=exp A instead of the usual U-linear definition. We confirmed gauge fixing with smearing preconditioning works perfectly for the purpose of finding the global minimum of the squared norm of the gauge field when $\beta$ is large(e.g. $\beta=5$). Our simulation results suggests the possibility of a realization of the infrared behaviour of the Gribov-Zwanziger theory.