RQM description of the charge form factor of the pion and its asymptotic behavior

The pion charge and scalar form factors, F-1(Q(2)) and F-0(Q(2)), are first calculated in different forms of relativistic quantum mechanics. This is done using the solution of a mass operator that contains both confinement and one-gluon exchange interactions. Results of calculations, based on a one-body current, are compared to experiment for the first one. As could be expected, those point form, and instant and front-form ones in a parallel momentum configuration fail to reproduce experiment. The other results corresponding to a perpendicular momentum configuration (instant form in the Breit frame and front form with q(+) = 0) do much better. The comparison of charge and scalar form factors shows that the spin-1/2 nature of the constituents plays an important role. Taking into account that only the last set of results represents a reasonable basis for improving the description of the charge form factor, this one is then discussed with regard to the asymptotic QCD power law behavior Q(-2). The contribution of two-body currents in achieving the right power law is considered while the scalar form factor, F-0(Q(2)), is shown to have the right power law behavior in any case. The low-Q(2) behavior of the charge form factor and the pion decay constant are also discussed.