Pion Interactions in Chiral Field Theories

Abstract

We study in various chiral models the pion charge radius, $π_{e3}$ form factor ratio, $π^\circ \to γγ$ amplitude, charge pion polarizabilities, $γγ\to π^\circ π^\circ$ amplitude at low energies and the $ππ$ s-wave I = 0 scattering length. We find that a quark-level linear sigma-model approach (also being consistent with tree-level vector meson dominance) is quite compatible with all of the above data.