RG solutions for \alpha_s at large N_c in d=3+1 QCD

Abstract

Solutions of RG equations for $\beta(\alpha)$ and $\alpha(Q)$ are found in the class of meromorphic functions satisfying asymptotic conditions at large $Q$ (resp. small $\alpha)$, and analyticity properties in the $Q^2$ plane. The resulting $\alpha_R(Q)$ is finite in the Euclidean $Q^2$ region and agrees well at $Q\geq 1$ GeV with the $\bar{MS} \alpha_s(Q)$.