Electromagnetic Form Factor of a Composed Particle in the Light-Front

The violation of the rotational symmetry constraint of the matrix elements of the plus component of the vector current, in the Drell-Yan frame, is studied using an analytical and covariant model of spin-1 composite particle. The contributions from pair terms or zero modes, if missed cause the violation of the rotational symmetry. We reanalyze the prescription by Grach and Kondratyuk to extract form factors which can eliminate theses contributions in particular models.