Null-plane phenomenology for the pion decay constant and radius

The pion decay constant and the electromagnetic form factor are computed by using quark diagrams and projecting the bound-state wave function on the null plane. We show that the resulting formulas are the same as those of the Hamiltonian front-form scheme. The connection between the radius ($r_{\pi }$) and the pion decay constant ($f_{\pi }$) is studied using different models of confinement.