Electromagnetic spin-1 form-factor free of zero-modes

TL;DR

This paper investigates the electromagnetic form-factors of a spin-1 system within a light-front quark model, addressing zero-mode contributions to preserve rotational symmetry and improve form-factor calculations.

Contribution

It introduces a method to eliminate rotational symmetry breaking by computing zero-mode contributions from valence matrix elements in spin-1 form-factor calculations.

Findings

Zero-mode contributions are essential for accurate form-factor extraction.

The method preserves rotational symmetry in light-front calculations.

Improved consistency across different prescriptions for form-factor computation.

Abstract

The electromagnetic current~$J^+$ for spin-1, is used here to extract the electromagnetic form-factors of a light-front constituent quark model. The charge ($G_0$), magnetic ($G_1$) and quadrupole $G_2$ form factors are calculated using different prescriptions known in the literature, for the combinations of the four independent matrix elements of the current between the polarisations states in the Drell-Yan frame. However, the results for some prescriptions relying only on the valence contribution breaks the rotational symmetry as they violate the angular condition. In the present work, we use some relations between the matrix elements of the electromagnetic current in order to eliminate the breaking of the rotational symmetry, by computing the zero-mode contributions to matrix elements resorting only to the valence ones.