The Effective QCD Lagrangian and Renormalization Group Approach
The perturbative part of the effective QCD Lagrangian was constructed by the renormalization group approach in the 4-loop approximation. It was extrapolated in the non-perturbative region under the assumption of the existence of gluon condensate at (F_{μν}^j)^2=F_0^2. The best result is F_0^2\approx 0.4 GeV^4.
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