Instanton size distribution: Repulsion or an infrared fixed point?

We discuss available information about the instanton size distribution d(ρ), which comes from lattice simulations and the interacting instanton liquid model. First, we demonstrate that they agree quite well. Second, we also show that an alternative idea, based on the infrared fixed point, can also reproduce the shape of d(ρ). Third, we discuss how one can use lattice methods to clarify the nature of the suppression of the large-size instantons.