The Joint Extraction of m_s and V_us From Hadronic Tau Decay Data

Abstract

We discuss the simultaneous determination of m_s and V_us from flavor-breaking hadronic tau decay sum rules, focussing on weight choices designed to better control problems associated with the slow convergence of the relevant integrated D=2 OPE series. The results are found to display improved stability and consistency relative to those of conventional analyses based on the ``(k,0) spectral weights''. The results for m_s agree well with those of recent strange scalar sum rule and strange pseudoscalar sum rule and lattice analyses. Results for V_us agree within errors with those of lattice-input-based K_{ell 3} and Gamma [K_{mu 2}]/\Gamma [pi_{mu 2}] analyses. Very significant error reductions are shown to be expected, especially for V_us, once improved strange spectral data from the B factory experiments becomes available.