Paper detail

Lattice evidence for the family of decoupling solutions of Landau gauge Yang-Mills theory

We show that the low-momentum behavior of the lattice Landau-gauge gluon and ghost propagators is sensitive to the lowest non-trivial eigenvalue (λ_1) of the Faddeev-Popov operator. If the gauge fixing favors Gribov copies with small λ_1 the ghost dressing function rises more rapidly towards zero momentum than on copies with large λ_1. This effect is seen for momenta below 1 GeV, and interestingly also for the gluon propagator at momenta below 0.2 GeV: For large λ_1 the gluon propagator levels out to a lower value at zero momentum than for small λ_1. For momenta above 1 GeV no dependence on Gribov copies is seen. Although our data is only for a single lattice size and spacing, a comparison to the corresponding (decoupling) solutions from the DSE/FRGE study of Fischer, Maas and Pawlowski [Annals of Physics 324 (2009) 2408] yields already a good qualitative agreement.