The QNP series of international conferences on Quarks and Nuclear Physics is by now a well established and highly respected forum where the most recent developments in the field are discussed and communicated. QNP 2006 is the forth edition of this biennial meeting. Selected and refereed original contributions of QNP 2006 have been published in The European Physical Journal A - Hadrons and Nuclei (EPJ A), while the present proceedings book, in addition to reprinting the articles published in EPJ A, further includes all other contributions selected and accepted by the organizing committee for publication and archiving.

This book is devoted to some recently developed techniques in quantum field theory (QFT), as well as to their main applications to different areas of parti cle physics. All together they are known as the effective or phenomenological Lagrangian formalism. Motivated by the enormous amount of work carried out in this field during the last years, our purpose when writing this book has been to give a modern and pedagogical exposition of the most relevant as pects of the topic. We hope that our efforts will be useful, both for graduated students in the search for a solid theoretical background in modern phe nomenology and for more experimented particle physicists willing to learn about this field or to start working on it. Even though we have tried to keep the book as self-contained as possible, it has been written assuming that the reader is familiar, at least, with the most basic concepts and techniques of QFT, gauge theories, the standard model (SM) and differential geometry, at the level of graduate studies. It is therefore possible that senior high-energy physicists may find the book too detailed and so they could probably omit several sections. The book is divided into two main parts and the appendices. In the first part we introduce the fundamentals of the effective Lagrangian formalism and other basic topics such as Ward identities, non-linear sigma models (NLSM), spontaneous symmetry breaking (SSB), anomalies, the SM symmetries, etc."

This book presents a detailed and pedagogical exposition of the effective Lagrangian techniques and their applications to high-energy physics. It covers the main theoretical ideas and describes comprehensively how to use them in different fields, such as chiral perturbation theory and the symmetry breaking sector of the standard model and even low-energy quantum gravity. The book is written in the language of modern quantum field theory. Some of the theoretical topics treated are: decoupling, the Goldstone theorem, the non-linear sigma model, anomalies, the Wess--Zumino--Witten term, and the equivalence theorem.