Related papers: Resolving the tau versus electroproduction discrep…
Sum rule tests are performed on the spectral data for (i) flavor 'ud' vector- current-induced hadronic tau decays and (ii) e^+ e^- hadroproduction, in the region below s~3-4 GeV^2, where discrepancies exist between the isospin-…
OPE constraints are studied as a means of distinguishing between the versions of the I=1 vector spectral function extracted from (i) inclusive I=1 hadronic electroproduction cross-sections and (ii) inclusive I=1 hadronic tau decay data,…
The interpretation of results of recent tau decay determinations of |V_us|, which yield values ~3 sigma low compared to 3-family unitarity expectations, is complicated by the slow convergence of the relevant integrated D=2 OPE series. We…
Sum rule constraints dominated by the independent high-scale input, alpha_s(M_Z), are shown to be satisfied by I=1 spectral data from hadronic tau decays, but violated by the pre-2005 electroproduction (EM) cross-section data.…
A sum rule for determining |V_us| from a combination of hadronic tau decay and electroproduction data is discussed. Indications of problems with analogous, purely tau-decay-based analyses, most likely associated with slow convergence of the…
Hadronic tau decay data is used to study the reliability of various finite energy sum rules (FESR's). For intermediate scales (of order 2-3 GeV^2), those FESR's with weights s^k are found to have significant errors, whereas those with…
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…
Vacuum polarization integrals involve the vector spectral functions which can be experimentally determined from two sources: (i) e+e- annihilation cross sections and (ii) hadronic tau decays. Recently results with comparable precision have…
I review sum rule determinations of |V_us| employing hadronic tau decay data, taking into account recent HFAG updates of exclusive tau branching fractions and paying special attention to the impact of the slow convergence of the relevant…
We describe how complications encountered in the extraction of V_us from flavor-breaking hadronic tau decay sum rules, in particular those associated with the slower than previously anticipated convergence of the relevant D=2 OPE series,…
We study extractions of |V_us| based on finite energy sum rule (FESR) analyses of hadronic tau decay data. We show (i) that the ``(0,0) spectral weight'' implementation (proposed previously in the literature as a favorable version of this…
Recent ALEPH/OPAL data on the V-A spectral functions from hadronic tau decays are used for fixing the QCD continuum threshold at which the first and second Weinberg sum rules should be satisfied in the chiral limit, and for predicting the…
We study the simultaneous determination of m_s and V_us from flavor-breaking hadronic tau decay sum rules using weights designed to bring under better control problems associated with the slow convergence of the relevant D=2 OPE series.…
The operator product expansion (OPE) for the difference of vector and axial current correlators is analyzed for complex values of momentum q^2. The vector and axial spectral functions, taken from hadronic tau-decay data, are treated with…
A critical review of hadronic tau decay data based determinations of |V_{us}| is given, focussing on the impact of the slow convergence of the integrated D=2 OPE series for the conventional flavor-breaking sum rule determination and the…
We update the extraction of |V_{us}| from hadronic tau decay data in light of recent BaBar and Belle results on the branching fractions of a number of important strange decay modes. A range of sum rule analyses is performed, particular…
The thorough analysis of the ALEPH data on hadronic tau-decay is performed in the framework of QCD. The perturbative calculations are performed in 3 and 4-loop approximations. The terms of the operator product expansion (OPE) are accounted…
Vacuum polarization integrals involve the vector spectral functions which can be experimentally determined from two sources: (i) e+e- annihilation cross sections and (ii) hadronic tau decays. Recently results with comparable precision have…
We study the reliability of extractions of |V_{us}| based on flavor-breaking hadronic tau decay sum rules. The ``(0,0) spectral weight'', proposed previously as a favorable candidate for this extraction, is shown to produce results having…
The spectral function $\rho_{V-A}(s)$ is determined from ALEPH and OPAL data on hadronic tau decays using a neural network parametrization trained to retain the full experimental information on errors, their correlations and chiral sum…