Eletroweak Form Factors in the Light-Front for Spin-1 Particles

TL;DR

This paper investigates the electromagnetic form factors of spin-1 particles using light-front dynamics, revealing issues with rotational symmetry and proposing a method to isolate zero-mode contributions analytically.

Contribution

It introduces an analytical approach to separate zero-mode contributions in light-front calculations of spin-1 form factors, addressing rotational symmetry violations.

Findings

Zero modes cause violations of rotational symmetry in light-front calculations.

An analytical method isolates zero-mode contributions in the Drell-Yan-West frame.

The approach improves the understanding of electromagnetic properties of spin-1 particles.

Abstract

The contribution of the light-front valence wave function to the electromagnetic current of spin-1 composite particles is not enough to warranty the proper transformation of the current under rotations. The naive derivation of the plus component of the current in the Drell-Yan-West frame within an analytical and covariant model of the vertex leads to the violation of the rotational symmetry. Computing the form-factors in a quasi Drell-Yan-West frame $q^+\rightarrow 0$, we were able to separate out in an analytical form the contributions from Z-diagrams or zero modes using the instant-form cartesian polarization basis.