Strong coupling from hadronic τ decays: A critical appraisal

Diogo Boito, Maarten Golterman, Kim Maltman, and Santiago Peris
Phys. Rev. D 95, 034024 – Published 22 February 2017

Abstract

Several different analysis methods have been developed to determine the strong coupling via finite-energy sum-rule analyses of hadronic τ decay data. While most methods agree on the existence of the well-known ambiguity in the choice of a resummation scheme due to the slow convergence of QCD perturbation theory at the τ mass, there is an ongoing controversy over how to deal properly with nonperturbative effects. These are small, but not negligible, and include quark-hadron “duality violations” (i.e., resonance effects) which are not described by the operator product expansion (OPE). In one approach, an attempt is made to suppress duality violations enough that they might become negligible. The number of OPE parameters to be fit, however, then exceeds the number of available sum rules, necessitating an uncontrolled OPE truncation, in which a number of higher-dimension OPE contributions in general present in QCD are set to zero by hand. In the second approach, truncation of the OPE is avoided by construction, and duality violations are taken into account explicitly, using a physically motivated model. In this article, we provide a critical appraisal of a recent analysis employing the first approach and demonstrate that it fails to properly account for nonperturbative effects, making the resulting determination of the strong coupling unreliable. The second approach, in contrast, passes all self-consistency tests, and provides a competitive determination of the strong coupling from τ decays.

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  • Received 21 November 2016

DOI:https://doi.org/10.1103/PhysRevD.95.034024

© 2017 American Physical Society

Physics Subject Headings (PhySH)

Particles & Fields

Authors & Affiliations

Diogo Boito1, Maarten Golterman2, Kim Maltman3,4, and Santiago Peris5

  • 1Instituto de Física de São Carlos, Universidade de São Paulo, CP 369, 13570-970, São Carlos, SP, Brazil
  • 2Department of Physics and Astronomy, San Francisco State University, San Francisco, California 94132, USA
  • 3Department of Mathematics and Statistics, York University, Toronto, Ontario M3J 1P3, Canada
  • 4CSSM, University of Adelaide, Adelaide, South Australia 5005, Australia
  • 5Department of Physics and IFAE-BIST, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Barcelona, Spain

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Issue

Vol. 95, Iss. 3 — 1 February 2017

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