Nonstandard Approach to Hadronic Tau Decays

A method based on the nonperturbative expansion technique in QCD is applied to calculate different physical quantities connected with experimental tau-data. It combines an optimization procedure of variational type with a regular way of calculating corrections and includes the nonperturbative character of the light quark masses and summation of quark threshold singularities. The theoretical description of examined quantities includes an infrared region as part of the interval of integration and, therefore, they cannot be directly calculated within the standard perturbative QCD. It is demonstrated that the method suggested allows its to describe well the R-tau-ratio, the light-quark Adler function, and the smeared R-Delta-function clown to the lowest energy scale.