Chiral perturbation theory confronted with experiment

The general framework and the present status of the low energy theory of the standard model are briefly reviewed. Recent applications to a few topic of interest for the determinations of Vud and of Vus are discussedComment: Talk given at the DAPHNE 2004 Workshop, Frascati, June 7 - 11, 2004; 9 pages, uses frascatiphys.st

On some properties of the fourth-rank hadronic vacuum polarization tensor and the anomalous magnetic moment of the muon

Some short-distance properties of the fourth-rank hadronic vacuum polarization tensor are re-examined.Their consequences are critically discussed in the context of the hadronic light-by-light scattering contribution to the anomalous magnetic moment of the muon.Comment: Latex2e, 19 page

Minimal Hadronic Ansatz to Large-Nc QCD and Hadronic tau Decay

I report on some recent work done in collaboration with Santi Peris and Boris Phily (hep-ph/0007338) where, using the Aleph data on vector and axial-vector spectral functions, we test simple duality properties of QCD in the large-Nc limit which emerge in the approximation of a {\it minimal hadronic ansatz} of a spectrum of narrow states. These duality properties relate the short- and long-distance behaviours of specific correlation functions, which are order parameters of spontaneous chiral symmetry breaking, in a way that we find well supported by the data.Comment: 7 pages with 3 figures. Latex file. Contribution to the Euroconference QCD00, Montpellier, Franc

A new start for local composite operators

We present a formalism for local composite operators. The corresponding effective potential is unique, multiplicatively renormalizable, it is the sum of 1PI diagrams and can be interpreted as an energy-density. First we apply this method to $\lambda \Phi^4$ theory where we check renormalizability up to three loops and secondly to the Coleman-Weinberg model where the gauge independence of the effective potential for the local composite operator $\phi\phi^*$ is explicitely checked up to two loops.Comment: 20 page

On the holomorphic factorization for superconformal fields

For a generic value of the central charge, we prove the holomorphic factorization of partition functions for free superconformal fields which are defined on a compact Riemann surface without boundary. The partition functions are viewed as functionals of the Beltrami coefficients and their fermionic partners which variables parametrize superconformal classes of metrics.Comment: 5 pages, LATEX, MPI-Ph/92-7