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alpha_s from tau decays: Contour-improved versus fixed-order summation in a new QCD perturbation expansion
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SYSNO ASEP 0345228 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title alpha_s from tau decays: Contour-improved versus fixed-order summation in a new QCD perturbation expansion Author(s) Caprini, I. (RO)
Fischer, Jan (FZU-D) RIDSource Title European Physical Journal C. - : Springer - ISSN 1434-6044
Roč. 64, č. 1 (2009), s. 35-45Number of pages 11 s. Language eng - English Country DE - Germany Keywords strong coupling ; tau decay ; QCD ; perturbation ; expansion ; conformal mapping Subject RIV BF - Elementary Particles and High Energy Physics R&D Projects LA08015 GA MŠMT - Ministry of Education, Youth and Sports (MEYS) CEZ AV0Z10100502 - FZU-D (2005-2011) UT WOS 000271119700004 DOI 10.1140/epjc/s10052-009-1142-8 Annotation We consider the determination of $/alpha_s$ from τ hadronic decays, by investigating the CIPT and the FOPT renormalization group summations in the frame of a new perturbation expansion of QCD, which incorporates in a systematic way the available information about the divergent character of the series. The new expansion functions are defined by the analytic continuation in the Borel complex plane, achieved through an optimal conformal mapping. Using a model discussed by Beneke and Jamin, we show that the new CIPT approaches the true results with great precision when the perturbative order is increased, while the new FOPT gives a less accurate description in the regions where the imaginary logarithms present in the expansion of the running coupling are large. From the new CIPT we predict $/alpha_s(m_/tau^2)= 0.320 ^{+0.011}_{-0.009}$. Workplace Institute of Physics Contact Kristina Potocká, potocka@fzu.cz, Tel.: 220 318 579 Year of Publishing 2011
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