ONCE MORE ON THE ROLE OF THE BOUND-STATE WAVE-FUNCTION IN THE LEPTONIC DECAYS OF LIGHT HADRONS

The decay of light pseudoscalar mesons into a lepton pair with the rel ativistic momentum space wave function (w.f.) of the meson is analysed . It is shown that the real part of the decay amplitude is defined by the transition form factor F with the dependence of the meson w.f. The calculation of F in the extreme static limit without knowing the expl icit form of the w.f. is also considered. We analyze the ratio of disp ersive to absorptive parts for decay pi(0) --> e(+) e(-). Numerical ca lculations of the branching ratio Br(pi(0) --> e(+) e(-)/gamma gamma) = 7.0 . 10(-8) using the confinement-type w.f. of the pi(0)-meson are in good agreement with recent experimental data.