$R_{e^ + e^ - } ,\,\Gamma _{had}^{Z^0 } $ AND αs: DO THE EXPERIMENTAL DATA AGREE WITH PERTURBATIVE QCD?

Abstract

We examine the present experimental determinations of the two related quantities: [Formula: see text] and [Formula: see text] and compare their values with the predictions of perturbative QCD. Both sets of data consistently lie systematically above the theoretical values. However, they are shown to be mutually consistent with a strong-interaction correction roughly twice the magnitude of that calculated within the framework of perturbative QCD. We conclude that this seems to point to the failure of this approach to correctly account for the non-trivial structure of the QCD vacuum and thus of long-distance effects which may pervade even the high-energy regime.