Analytic perturbation theory for QCD practitioners and upsilon decay

Within ghost-free analytic perturbation theory (APT), devised in the last decade for low-energy QCD, simple approximations are proposed for three-loop analytic couplings and their effective powers, in both the spacelike (Euclidean) and timelike (Minkowskian) regions, accurate enough in a large range...

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Bibliographic Details
Published in:Physics of atomic nuclei 2007-04, Vol.70 (4), p.775-783
Main Authors: Shirkov, D. V., Zayakin, A. V.
Format: Article
Language:English
Subjects:
APPROXIMATIONS
COUPLINGS
EUCLIDEAN SPACE
GAMMA DECAY
GEV RANGE
MINKOWSKI SPACE
PERTURBATION THEORY
PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
QUANTUM CHROMODYNAMICS
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Summary:Within ghost-free analytic perturbation theory (APT), devised in the last decade for low-energy QCD, simple approximations are proposed for three-loop analytic couplings and their effective powers, in both the spacelike (Euclidean) and timelike (Minkowskian) regions, accurate enough in a large range (1-100 GeV) of current physical interest. Effectiveness of the new model is illustrated by the example of {gamma}(1S) decay, where a standard analysis gives {alpha}{sub s}(M{sub {gamma}}) = 0.170 {+-} 0.004, which is inconsistent with the bulk of data on {alpha}{sub s}. Instead, we obtain {alpha}{sub s}{sup mod}(M{sub {gamma}}) = 0.185 {+-} 0.005, which corresponds to {alpha}{sub s}{sup mod}(M{sub Z} = 0.120 {+-} 0.002, which is close to the world-average value. The issue of scale uncertainty for {gamma} decay is also discussed.
ISSN:1063-7788
1562-692X
DOI:10.1134/S1063778807040205