Asymptotic behavior of the gluon propagator from lattice QCD - art. no. 094509

We study the flavorless gluon propagator in the Landau gauge from high stat istics lattice calculations. Hypercubic artifacts are efficiently eliminate d by taking the Sigma p(mu)(4)-->0 limit. The propagator is fitted to the t hree-loops perturbative formula in an energy window ranging from similar to 2.5 GeV up to similar to 5.5 GeV. alpha(s) is extracted from the best fit in a continuous set of renormalization schemes. The fits are very good, wit h a chi(2) per DOF smaller than 1. We propose a more stringent test of asym ptotic scaling based on scheme independence of the resulting Lambda(<(MS)ov er bar>). This method shows that asymptotic scaling at three loops is not r eached by the gluon propagator although we use rather large energies. We ar e only able to obtain an effective flavorless three-loops estimate Lambda(< (MS)over bar>)((3)) = 353 +/- 2(-10)(+25) MeV. We argue that the real asymp totic value for Lambda(<(MS)over bar>) should plausibly be smaller. [S0556- 2821(99)06519-4].