title: Scheme Variations of the QCD Coupling and Hadronic τ Decays.
abstract: The quantum chromodynamics (QCD) coupling α_{s} is not a physical observable of the theory, since it depends on conventions related to the renormalization procedure. We introduce a definition of the QCD coupling, denoted by α[over ^]_{s}, whose running is explicitly renormalization scheme invariant. The scheme dependence of the new coupling α[over ^]_{s} is parametrized by a single parameter C, related to transformations of the QCD scale Λ. It is demonstrated that appropriate choices of C can lead to substantial improvements in the perturbative prediction of physical observables. As phenomenological applications, we study e^{+}e^{-} scattering and decays of the τ lepton into hadrons, both being governed by the QCD Adler function.
authors: Instituto de Física de São Carlos, Universidade de São Paulo, CP 369, 13560-970 São Carlos, São Paulo, Brazil.
authors: Diogo
authors: D
authors: Boito
authors: IFAE, BIST, Campus UAB, 08193 Bellaterra (Barcelona) Spain and ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain.
authors: Matthias
authors: M
authors: Jamin
authors: IFAE, BIST, Campus UAB, 08193 Bellaterra (Barcelona) Spain.
authors: Ramon
authors: R
authors: Miravitllas