A Chiral Perturbation Theory Primer

TL;DR

This paper provides an introductory overview of chiral perturbation theory, covering QCD symmetries, spontaneous symmetry breaking, and applications to mesons and baryons, serving as a foundational guide for researchers.

Contribution

It offers a comprehensive, pedagogical introduction to chiral perturbation theory, detailing theoretical principles and methods for mesonic and baryonic interactions.

Findings

Explains QCD global symmetries and their breaking.

Demonstrates Goldstone theorem in chiral symmetry breaking.

Outlines construction of chiral Lagrangian for mesons and baryons.

Abstract

These lecture notes include the following topics. Chapter 1 deals with QCD and its global symmetries in the chiral limit, explicit symmetry breaking in terms of the quark masses, and the concept of Green functions and Ward identities reflecting the underlying chiral symmetry. In Chapter 2 the idea of a spontaneous breakdown of a global symmetry is discussed and its consequences in terms of the Goldstone theorem are demonstrated. Chapter 3 deals with mesonic chiral perturbation theory and the principles entering the construction of the chiral Lagrangian are outlined. In Chapter 4 the methods are extended to include the interaction between Goldstone bosons and baryons in the single-baryon sector.