THE NEXT STEP IN LEPTONIC DECAYS OF ETA AND K_L BOUND STATES

A systematic discussion of the probability of eta and K_L bound-state decays— and (l=e, μ)—within a three-dimensional reduction to the two-body quantum field theory is presented. The bound-state vertex function depends on the relative momentum of constituent-like particles. A structure-transition form factor is defined by a confinement-type quark-antiquark wave function. The phenomenology of this kind of decays is analyzed.