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Physics Letters B 626 (2005) 101-110
Strange Quark, Tachyonic Gluon Masses and $V_{us}$ from Hadronic Tau Decays
S. Narison1

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 ($m_s$) and tachyonic gluon ($\lambda^2$) masses . Using the mean value of $\lambda^2$ from a sum rule analysis of different channels, we deduce the invariant strange quark mass $\hat{m}_s= (115.6\pm16.8)$ MeV to order $\alpha_s^3$, which leads to the running mass $\bar{m}_s$(2 GeV)= ($103.1\pm15.1$) MeV. The case $\lambda^2 = 0$ leads to a lower value $\bar{m}_s$(2 GeV)= ($70.1\pm18.4$) MeV, in the boarderline of the lower bound 90 MeV derived from different sum rules, and lower than most of the existing determinations of $m_s$. We also obtain an interesting though less competitive estimate of the CKM angle: $\left|V_{us}\right|=0.2185\pm0.036.
1 :  LPTA - Laboratoire de Physique Théorique et Astroparticules
Physique/Physique des Hautes Energies - Phénoménologie
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