On the kinematics of the centre of charge of a spinning particle

TL;DR

This paper proposes a model where the charge and mass centers of a spinning particle are distinct, with the charge moving in a helical path at light speed, leading to new insights into particle spin and magnetic moments.

Contribution

It introduces a model where the charge's motion is separate from the mass center, resulting in a fourth order differential equation and a better understanding of spin and magnetic moments.

Findings

Charge center moves in a helical path at light speed.

Model requires a Lagrangian depending on acceleration.

Provides a refined classical model of elementary particles.

Abstract

In particle physics, most of the classical models consider that the centre of mass and centre of charge of an elementary particle, are the same point. This presumes some particular relationship between the charge and mass distribution, a feature which cannot be checked experimentally. In this paper we give three different kinds of arguments suggesting that, if assumed different points, the centre of charge of an elementary spinning particle moves in a helical motion at the speed of light, and it thus satisfies, in general, a fourth order differential equation. If assumed a kind of rigid body structure, it is sufficient the description of the centre of charge to describe also the evolution of the centre of mass and the rotation of the body. This assumption of a separation betwen the centre of mass and centre of charge gives a contribution to the spin of the system and also justifies the existence of a magnetic moment produced by the relative motion of the centre of charge. This corresponds to an improved model of a charged elementary particle, than the point particle case. This means that a Lagrangian formalism for describing elementary spinning particles has to depend, at least, up to the acceleration of the position of the charge, to properly obtain fourth order dynamical equations. This result is compared with the description of a classical Dirac particle obtained from a general Lagrangian formalism for describing spinning particles.