Precocious scaling and nonperturbative effects in QCD

The onset of nonperturbative effects in QCD is studied in two ways: (1) by means of the nonvanishing vacuum expectation value of 〈g ² F ²〉 introduced by Shifman, Vainshtein and Zakharov; (2) using a finite energy sum rule (FESR) for the renormalization group function β. Our considerations are based upon the recently proposed “physical” β_MMOM, which is gauge invariant and shows explicit mass-decoupling.