On ambiguities of the spin-1 electromagnetic form factors in light-front dynamics

Abstract

In light-front dynamics, different ways of approximately calculating the electromagnetic form factors of any spin-1 system, proceeding from different sets of matrix elements of the J + current component, lead to different form factors. All these ways available in literature are analyzed. The differences between form factors are found analytically in terms of nonphysical contributions coming from the dependence of the electromagnetic vertex on the light-front plane. We show that it is impossible to improve form factors by combining any matrix elements of J +. All the nonphysical contributions are removed, if, in addition to J +, one takes into account other components of the current.