Tests of three-flavor chiral perturbation theory

We review experimental tests of three-flavor (u,d,s) chiral perturbation theory (ChPT). These include measurements of pion and kaon polarizabilities, the chiral anomaly amplitudes for processes such as [Formula: see text], [Formula: see text] and [Formula: see text]KK[Formula: see text], as well as the lifetimes of the neutral pion and eta. These observables are extracted primarily through ultra-peripheral Primakoff scattering of high-energy particles from virtual photons in the Coulomb field of nuclei. Comparing data to two-flavor and three-flavor predictions allows us to evaluate how well ChPT describes light meson dynamics and the role of the strange quark in spontaneous chiral symmetry breaking.