Magnetic focusing in atomic, nuclear and hadronic processes

TL;DR

This paper explores how homogeneous magnetic fields can focus and amplify certain atomic, nuclear, and hadronic processes involving charged particles, affecting probabilities and phase space in measurable ways.

Contribution

It introduces a quantitative analysis of focusing effects in magnetic fields on various processes, providing formulas and examples for amplification factors.

Findings

Focusing effects can amplify process probabilities proportionally to eB.

Magnetic fields influence phase space and Landau level energies.

Examples include neutron beta decay, positronium decay, and electron-positron pair production.

Abstract

Processes with oppositely charged spinor particles in initial and/or final states in homogeneous magnetic field B are subject to focusing effects in their relative motion, which yield the amplifying factors in probabilities growing as $eB$. In addition the increasing energy of some Landau levels influences the phase space. As a result some processes in the proper spin states can be enlarged as $\sim \frac{eB}{\kappa^2}$, where $\kappa^2$ is the characteristic 2d phase space factor available without magnetic field. Several examples, including neutron $\beta$ decay, positronium decay and $e^+e^-$ pair production, are quantitatively considered.