100 research outputs found
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 -function is proportional to the spectral
density, which confirms a hypothesis due to Schwinger.Comment: 11 pages, 2 figure
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