Phenomenological connections of the processes π-→ν-bar3e, π-→ν-bareγ, a1→πρ, a1→πγ and π0→γγ

In recent years much attention has been paid to theoretical and experimental determination of form factors of the decays π-→ν-bareγ and π-→ν-bar3e. In particular, attempts are still made to measure more accurately the experimental values of the ratios of the form factors. We would like to show what estimates for these quantities can be obtained from the condition of a self-consistent phenomenological description of the processes a1→πρ, a1→πγ and π-→ν-bareγ. 10 refs