The strong coupling constant at small momentum as an instanton detector

Abstract

We present a study of ${\alpha }_{MOM}(p)$ at small p computed from the lattice. It shows a dramatic $\propto p^4$ 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}.

Comments: 12 pages, 4 figures