Non-perturbative power corrections to ghost and gluon propagators

We study the dominant non-perturbative power corrections to the ghost andgluon propagators in Landau gauge pure Yang-Mills theory using OPE and latticesimulations. The leading order Wilson coefficients are proven to be the samefor both propagators. The ratio of the ghost and gluon propagators is thus freefrom this dominant power correction. Indeed, a purely perturbative fit of thisratio gives smaller value ($\simeq 270$MeV) of $\Lambda_{\ms}$ than the oneobtained from the propagators separately($\simeq 320$MeV). This argues infavour of significant non-perturbative $\sim 1/q^2$ power corrections in theghost and gluon propagators. We check the self-consistency of the method.Comment: 14 pages, 4 figures; replaced with revised version, to appear in JHE