Applying Optimized Perturbation Theory to QCD at Low Energies

Abstract

We discuss the use of the optimization procedure based on the Principle of Minimal Sensitivity to the third-order calculation of {\mbox{$R_{e^{+}{e}^{-}}$}}. The effective coupling constant remains finite allowing us to apply the Poggio-Quinn-Weinberg smearing method down to energies below 1 GeV, where we find good agreement between theory and experiment. The couplant freezes to a value of ${\alpha }_s/\pi =0.26$ at zero energy which is in remarkable concordance with values obtained phenomenologically.

Talk presented at DPF 92 Meeting, Fermilab, Nov. 1992. 3 pages Latex and dpf92 math macros, uufile encoded ps files (name fig3.psf). DE-FG05-92ER40717-1