Brodsky, S. JPeláez Sagredo, José RamónToumbas, N.2023-06-202023-06-201999-08-011550-799810.1103/PhysRevD.60.037501https://hdl.handle.net/20.500.14352/59879©1999 The American Physical Society.We construct new phenomenological tests of perturbative QCD by considering a hypothetical au lepton of arbitrary mass which decays hadronically through the electromagnetic current. Its adronic branching ratio can be computed directly as an integral over the e⁺e⁻ annihilation cross section ratio, R_ (e⁺e⁻). More generally, we can design a set of commensurate scale relations which test the applicability and self-consistency of leading twist QCD predictions by varying the weight function away from the form associated with the V-A decay of the physical τ . This method allows the wide range of R_(e⁺e⁻) data (or other similar observables which define an effective charge) to be used as renormalization scheme and scale invariant probes of QCD. [S0556-2821(99)05713-6].engjournal articlehttp://dx.doi.org/10.1103/PhysRevD.60.037501http://journals.aps.orgopen access51-73Total cross-sectionInclusive muon productionPion form-factorCm energy-rangeSquare- root-SE+E annihilationSum-rulesRenormalization-schemeSpectral functionsHadron-productionFísica-Modelos matemáticosFísica matemática