  The study of the Dyson-Schwinger equations of Landau gauge Yang-Mills theory
has revealed two types of solutions for the gluon and ghost propagators, with a
scaling and a massive (decoupling) behavior in the extreme infrared,
respectively. We show that both types of solutions are quantitatively
reproduced by applying renormalization group equations of Callan-Symanzik type
in an epsilon expansion to the infrared limit of Landau gauge Yang-Mills theory
when a mass term for the gluons is added to the action. Only the decoupling
solution corresponds to an infrared-stable fixed point in three and four
space-time dimensions and is hence expected to be physically realized, in
agreement with the results of recent lattice calculations.
