Electromagnetic form factors of pion and rho in the three forms of relativistic kinematics

The electromagnetic form factors of the pion and the rho are obtained using the three forms of relativistic kinematics, instant form, point form and (light) front form. Simple representations of the mass operator together with single quark currents are employed with all the forms. The Poincar\'e covariant current operators are generated by the dynamics from single-quark currents that are covariant under the kinematic subgroup. Front form allows to reproduce the available data for the pion form factor. Instant form gives the qualitative picture for the pion form factor but fails to describe both the charge radius and the $Q^2$ dependence with reasonable quark model parameters. On the other hand point form is not able to reproduce qualitatively the experimental data with reasonable values for the wave function parameters. For the $\rho$ electromagnetic form factors, instant and front forms provide a consistent picture. The obtained results do not depend appreciably on the wave function used.