Strange quark, tachyonic gluon masses and [formula omitted] from hadronic tau decays

Abstract

We apply, to the new OPAL data on V+A strange spectral functions, a suitable combination of QCD spectral sum rules directly sensitive to the combination of strange quark (ms) and tachyonic gluon (λ2) masses. Using the mean value of λ2 from a sum rule analysis of different channels, we deduce the invariant strange quark mass mˆs=(106−37+33) MeV to order αs3, which leads to the running mass m¯s(2 GeV)=(93−32+29) MeV. We also obtain an interesting though less accurate estimate of the CKM angle: |Vus|=0.217±0.019.