π- and a1-meson physics in current algebra at the quark level

The a1→π(ππ) S-wave decay and the low-energy ππ-scattering are considered within Current algebra at the quark level (CA)q and Chiral perturbation theory at the quark level (CHPT)q based on the Extended Nambu-Jona-Lasinio model with linear realization of chiral U(3) X U(3) symmetry. It is shown that low-energy interactions of a new kind, produced by convergent constituent-quark diagrams and being very useful for the theoretical understanding of experimental data on the processes under consideration, are very good blending with (CA)q and (CHPT)q. The contribution of these interactions is caused by the application of ordinary rules of quantum field theory. (author). 29 refs, 3 figs