Freezing of QCD coupling affects the short distance static potential

Abstract

A striking contradiction between lattice short range static potential (nf=0) and standard perturbative potential, observed by Bali G.S., is investigated in the framework of the background perturbation theory. With the use of the background coupling which contains the only background parameter - mass mB, fixed by fine structure fit in bottomonium, the lattice data are nicely explained without introduction of exotic short range linear potential with large "string tension" approx. 1 GeV squared. A significant difference between the background coupling and standard perturbative coupling is found in the range 0.05 fm < r<0.15 fm, while at larger distances, r > 0.3 fm the background coupling fast approaches the freezing value. Some problems concerning the strong coupling properties at short and long distances are discussed and solutions are suggested.