Electromagnetic Properties for Arbitrary Spin Particles: Part 2 $-$ Natural Moments and Transverse Charge Densities

TL;DR

This paper derives all natural electromagnetic moments for pointlike particles of any spin using light-cone helicity conservation, and applies these results to analyze transverse charge densities for arbitrary spin particles.

Contribution

It provides explicit formulas for light-cone helicity amplitudes and generalizes quark transverse charge densities to particles with arbitrary spin.

Findings

Derived all natural electromagnetic moments for arbitrary spin particles.

Expressed light-cone helicity amplitudes in terms of covariant vertex functions.

Generalized transverse charge density analysis to arbitrary spin particles.

Abstract

In a set of two papers, we propose to study an old-standing problem, namely the electromagnetic interaction for particles of arbitrary spin. Based on the assumption that light-cone helicity at tree level and $Q^2=0$ should be conserved non-trivially by the electromagnetic interaction, we are able to derive \emph{all} the natural electromagnetic moments for a pointlike particle of \emph{any} spin. In this second paper, we give explicit expressions for the light-cone helicity amplitudes in terms of covariant vertex functions, leading to the natural electromagnetic moments at $Q^2=0$. As an application of our results, we generalize the discussion of quark transverse charge densities to particles with arbitrary spin.