DECAYS OF η AND η' MESONS–AN INTRODUCTION

Abstract

Decays of η and η' mesons are a laboratory for low energy strong interactions. The rate of isospin breaking decays into three pions constrain ratios of the light quark masses. Particle distributions from hadronic decays allow to study the elementary processes of the low energy Quantum Chromodynamics: π - π and π - η interactions. Radiative and conversion decays of the η and η' mesons provide information about internal structure of the mesons and the decay mechanism is strongly influenced by vector meson resonances. The lecture gives an introduction to the common decays of η and η' mesons. The main theme of the lecture are three body decays: hadronic decays, radiative decays into π+π-γ, π0γγ and Dalitz decays into ℓ+ℓ-γ.