The strong coupling constant at small momentum as an instanton detector
  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}. 
Ph. Boucaud, F. De Soto, A. Le Yaouanc, J.P. Leroy, J. Micheli, H.   Moutarde, O. P\`ene, J. Rodr\'iguez-Quintero