Strange Quark Mass from the Invariant Mass Distribution of Cabibbo-Suppressed Tau Decays

Quark mass corrections to the τ hadronic width play a significant role only for the strange quark, hence providing a method for determining its mass. The experimental input is the vector plus axial-vector strange spectral function derived from a complete study of tau decays into strange hadronic final states performed by ALEPH. New results on strange decay modes from other experiments are also incorporated. The present analysis determines the strange quark mass at the Mτ mass scale using moments of the spectral function. Justified theoretical constraints are applied to the nonperturbative components and careful attention is paid to the treatment of the perturbative expansions of the moments which exhibit convergence problems. The result obtained, ms(M 2 τ ) = (120± 11exp ± 8Vus ± 19th) MeV = (120 +21 −26) MeV, is stable over the scale from Mτ down to about 1.4 GeV. Evolving this result to customary scales yields ms(1 GeV ) = (160 −35) MeV and ms(4 GeV ) = (116 −25) MeV.