Employing our previous framework to treat non-perturbative effects selfconsistently, including duality violations, we update the determination of the strong coupling, α s , using a modified version of the 1998 OPAL data, updated to reflect current values of exclusive mode hadronic τ decay branching fractions. To account for non-perturbative effects, non-linear, multi-parameter fits are necessary. We have, therefore, investigated the posterior probability distribution of the model parameters underlying our fits in more detail. We find that OPAL data alone provide only weak constraints on some of the parameters needed to model duality violations, especially in the case of fits involving axial vector channel data, making additional prior assumptions on the expected size of these parameters necessary at present. We provide evidence that this situation could be greatly improved if hadronic spectral functions based on the high-statistics BaBar and Belle data were to be made available.2

We apply an analysis method previously developed for the extraction of the strong coupling from the OPAL data to the recently revised ALEPH data for nonstrange hadronic τ decays. Our analysis yields the values α s (m 2 τ ) = 0.296±0.010 using fixed-order perturbation theory, and α s (m 2 τ ) = 0.310±0.014 using contourimproved perturbation theory. Averaging these values with our previously obtained values from the OPAL data, we find α s (m 2 τ ) = 0.303 ± 0.009, respectively, α s (m 2 τ ) = 0.319 ± 0.012. We present a critique of the analysis method employed previously, for example in analyses by the ALEPH and OPAL collaborations, and compare it with our own approach. Our conclusion is that non-perturbative effects limit the accuracy with which the strong coupling, an inherently perturbative quantity, can be extracted at energies as low as the τ mass. Our results further indicate that systematic errors on the determination of the strong coupling from analyses of hadronic τ -decay data have been underestimated in much of the existing literature.

Various moments of the hadronic spectral functions have been employed in the determination of the strong coupling α s from tau decays. In this work we study the behaviour of their perturbative series under different assumptions for the large-order behaviour of the Adler function, extending previous work on the tau hadronic width. We find that the moments can be divided into a small number of classes, whose characteristics depend only on generic features of the moment weight function and Adler function series. Some moments that are commonly employed in α s analyses from τ decays should be avoided because of their perturbative instability. This conclusion is corroborated by a simplified α s extraction from individual moments. Furthermore, under reasonable assumptions for the higher-order behaviour of the perturbative series, fixed-order perturbation theory (FOPT) provides the preferred framework for the renormalization group improvement of all moments that show good perturbative behaviour. Finally, we provide further evidence for the plausibility of the description of the Adler function in terms of a small number of leading renormalon singularities.

We present a new framework for the extraction of the strong coupling from hadronic τ decays through finite-energy sum rules. Our focus is on the small, but still significant non-perturbative effects that, in principle, affect both the central value and the systematic error. We employ a quantitative model in order to accommodate violations of quark-hadron duality, and enforce a consistent treatment of the higher-dimensional contributions of the Operator Product Expansion to our sum rules. Using 1998 OPAL data for the non-strange isovector vector and axial-vector spectral functions, we find the n f = 3 values α s (m 2 τ) = 0.307 ±0.019 in fixed-order perturbation theory, and 0.322±0.026 in contour-improved perturbation theory. For comparison, the original OPAL analysis of the same data led to the values 0.324 ± 0.014 (fixed-order) and 0.348 ± 0.021 (contour-improved).

Investigation at a φ-factory can shed light on several debated issues in particle physics. We discuss: i) recent theoretical development and experimental progress in kaon physics relevant for the Standard Model tests in the flavor sector, ii) the sensitivity we can reach in probing CPT and Quantum Mechanics from time evolution of entangled kaon states, iii) the interest for improving on the present measurements of non-leptonic and radiative decays of kaons and η/η′ mesons, iv) the contribution to understand the nature of light scalar mesons, and v) the opportunity to search for narrow di-lepton resonances suggested by recent models proposing a hidden dark-matter sector. We also report on the e + e − physics in the continuum with the measurements of (multi)hadronic cross sections and the study of γγ processes.