The strong coupling constant at small momentum as an instanton detector

Abstract

We present a study of ¿MOM(p) at small p computed from the lattice in the quenched approximation (nf = 0). It shows a dramatic proptop4 law which can be understood within an instanton liquid model. In this framework the prefactor gives a direct measure of the instanton density in thermalised configurations. A preliminary result for this density is 5.27(4) fm¿4.