The decay τ→3πντ and characteristics of a1 meson

In case of the τ→3πντ, the transition caused by the weak axial-vector hadronic current can be described by a resonant formula of the Breit-Wigner type. It contains all information on the interaction of decay products and has a pole corresponding to the a1 meson contribution. For the construction of functions of the Breit-Wigner type, the quark model of superconductivity type (QMST) was used. The a1→πρ meson vertex structure was studied on the basis of its connection with a number of related processes, e.g., the radiative decays a1→πγ and π→eνγ. (Z.S.) 2 tabs., 4 figs., 27 refs