Determination of alpha_s from tau decays

Abstract

Hadronic tau decays offer the possibility of determining the strong coupling alpha_s at relatively low energy. Precisely for this reason, however, good control over the perturbative QCD corrections, the non-perturbative condensate contributions in the framework of the operator product expansion (OPE), as well as the corrections going beyond the OPE, the duality violations (DVs), is required. On the perturbative QCD side, the contour-improved versus fixed-order resummation of the series is still an issue, and will be discussed. Regarding the analysis, self-consistent fits to the data including all theory parameters have to be performed, and this is also explained in some detail. The fit quantities are moment integrals of the tau spectral function data in a certain energy window and care should be taken to have acceptable perturbative behaviour of those moments as well as control over higher-dimensional operator corrections in the OPE.

8 pages, 2 figures. Proceedings of the Xth Quark Confinement and the Hadron Spectrum, 8-12 October 2012, Munich, Germany

References in corpus (7)

• Hadronic Z- and tau-Decays in Order alpha_s^4
• Alpha_s(M_Z) from hadronic tau decays
• Unraveling duality violations in hadronic tau decays
• ${\alpha }_s$ from $\tau$ decays: contour-improved versus fixed-order summation in a new QCD perturbation expansion
• Perturbative expansion of the QCD Adler function improved by renormalization-group summation and analytic continuation in the Borel plane
• A note on renormalon models for the determination of alpha_s(M_tau)
• On the perturbative expansion of tau hadronic spectral function moments