Comparison among Hamiltonian light-front formalisms

The electromagnetic elastic form factors of pseudoscalar and vector mesons are analyzed for space-like momentum transfers in terms of relativistic quark models based on the Hamiltonian light-front formalism elaborated in different reference frames (q+ = 0 and q+ 6= 0). As far as the one-body approximation for the electromagnetic current operator is concerned, it is shown that the predictions of the light-front approach at q+ = 0 should be preferred, particularly in case of light hadrons, because of: i) the relevant role played by the Z-graph at q+ 6= 0, and ii) the appropriate elimination of spurious effects, related to the orientation of the null hyperplane where the light-front wave function is defined. PACS numbers: 12.39.Ki; 14.40.Cs; 13.40.Gp