Chiral effective action of QCD: Precision tests, questions and electroweak extensions

Abstract

This talk first discusses some aspects of the chiral expansion with three light flavours related to the (non) applicability of the OZI rule. Next, the extension of ChPT to an effective theory of the full standard model is considered. Some applications of a systematic description of the coupling constants by sum rules (e.g. to the determination of quark masses and $K_{l3}$ decays) are presented.

Comments: 6 pages, plenary talk at the International Conference on QCD and Hadronic physics, Beijing 16-20 June 2005