Determination of the strange quark mass from Cabibbo-suppressed tau decayswith resummed perturbation theory in an effective scheme

We present an analysis of the m(s)(2)-corrections to Cabibbo-suppressed tau -lepton decays employing contour improved resummation within an effective scheme which is an essential new feature as compared to previous analyses. The whole perturbative QCD dynamics of the tau -system is described by the beta -function of the effective coupling constant and by two gamma -functio ns for the effective mass parameters of the strange quark in different spin channels. We analyze the stability of our results with regard to high-orde r terms in the perturbative expansion of the renormalization group function s. A numerical value for the strange quark mass in the (MS)over bar scheme is extracted: m(s)(M-tau) = 130 +/- 27(exp) +/- 9(th) MeV. After running to the scale 1 GeV this tranulates into m(s)(1GeV) = 176 +/- 37(exp) +/- 13(t h) MeV.