Pion Interactions in Chiral Field Theories

We study in various chiral models the pion charge radius, ${\pi }_{e3}$ form factor ratio, ${\pi }^{\circ }\to \gamma \gamma$ amplitude, charge pion polarizabilities, $\gamma \gamma \to {\pi }^{\circ }{\pi }^{\circ }$ amplitude at low energies and the $\pi \pi$ 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.