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Precise alpha_s from tau decay

Abstract : An updated measurement of α_s(m^2_τ) from ALEPH τ hadronic spectral functions is presented. We report a study of the perturbative prediction(s) showing that the fixed-order perturbation theory manifests convergence or principle problems not presented in the contour-improved calculation. Potential systematic effects from quark-hadron duality violations are estimated to be within the quoted systematic errors. The fit result is α_s(m^2_τ) = 0.344±0.005±0.007, where the first error is experimental and the second theoretical. After evolution, the α_s(m^2_z) determined from τ data is one of the most precise to date, in agreement with the corresponding N^3LO value derived from Z decays.
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http://hal.in2p3.fr/in2p3-00329854
Contributor : Sabine Starita <>
Submitted on : Friday, March 13, 2009 - 11:00:43 AM
Last modification on : Wednesday, October 14, 2020 - 3:42:28 AM

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B. Malaescu. Precise alpha_s from tau decay. 14th International QCD Conference (QCD 08), Jul 2008, Montpellier, France. pp.183-186, ⟨10.1016/j.nuclphysbps.2008.12.043⟩. ⟨in2p3-00329854⟩

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