Angular momentum dynamics of vortex particles in accelerators

TL;DR

This paper explores the behavior of vortex particles with orbital angular momentum in accelerators, revealing their potential for enhanced magnetic moments and discussing their stability and manipulation during acceleration.

Contribution

It provides the first detailed analysis of radiative and non-radiative OAM dynamics of relativistic vortex particles in accelerator environments.

Findings

OAM loss timescale exceeds typical acceleration durations.

Non-radiative OAM precession occurs at a distinct frequency from spin.

Resonances can disrupt OAM at lower energies than spin-polarized beams.

Abstract

While conventional experiments typically employ plane-wave states of particles with definite momenta, vortex states represent cylindrical waves carrying an orbital angular momentum (OAM) projection along the propagation direction. This projection can be arbitrarily large, granting charged particles magnetic moments orders of magnitude greater than those of plane-wave states. Consequently, vortex beams could complement or replace spin-polarized beams in high-energy collisions, accessing observables beyond the reach of conventional experiments. We investigate the radiative and non-radiative OAM dynamics for relativistic vortex particles in accelerators. Our results show that the timescale for OAM loss via photon emission significantly exceeds typical acceleration times. Non-radiative OAM dynamics is governed by precession at a frequency distinct from that of spin. Similar to spin tunes, this induces resonances that can disrupt OAM at much lower energies than for spin-polarized beams. Thus, we propose using linacs for acceleration of the vortex beams, while Siberian snakes can be adapted for OAM manipulations.