The Strange Quark Mass, alpha_s and the Chiral Limit Electroweak Penguin Matrix Elements From Hadronic Tau Decay Data

Abstract

Hadronic tau decay data provides access to the light quark vector (V) and axial vector (A) spectral functions. This makes possible investigations of the dynamics of QCD at intermediate scales and improved determinations of certain QCD/Standard Model parameters. We discuss three such applications: (1) the investigation of the nature of duality violation in QCD at intermediate scales (and its relation to the determination of alpha_s); (2) the extraction of m_s from flavor-breaking differences of flavor 'ud' and 'us' data; and (3) the determination of the dimension D=6 term in the OPE for the flavor 'ud' V-A correlator difference. The latter is relevant to the evaluation of the chiral limit values of the K-->pi pi electroweak penguin matrix elements, and hence to our understanding of expectations for epsilon'/epsilon in the Standard Model.