The Bjorken Sum Rule in the Analytic Approach to Perturbative QCD

Results of applying analytic perturbation theory (APT) to the Bjorken sum rule are presented. We study the third-order QCD correction within the analytic approach and investigate its renormalization scheme dependence. We demonstrate that, in the framework of the method, theoretical predictions of the Bjorken sum rule are, practically, scheme independent for the entire interval of momentum transfer.Comment: 12 pages, 3 eps figures, uses elsart.cl

Analytic perturbation theory in QCD and Schwinger's connection between the beta-function and the spectral density

We argue that a technique called analytic perturbation theory leads to a well-defined method for analytically continuing the running coupling constant from the spacelike to the timelike region, which allows us to give a self-consistent definition of the running coupling constant for timelike momentum. The corresponding $\beta$-function is proportional to the spectral density, which confirms a hypothesis due to Schwinger.Comment: 11 pages, 2 figure