Comment on "Monopole production via photon fusion and Drell-Yan processes: MadGraph implementation and perturbativity via velocity-dependent coupling and magnetic moment as novel features"

TL;DR

This paper critically examines a recent study on monopole production, clarifying misconceptions about the magnetic field configuration and quantisation conditions, and emphasizing the importance of correct field identification.

Contribution

The paper refutes a previous claim by demonstrating that the modified Wu-Yang configuration leads to multiple quantisation conditions, correcting the understanding of monopole magnetic fields.

Findings

Incorrect identification of magnetic fields in the previous study

Modified Wu-Yang configuration results in infinite quantisation conditions

Clarification of magnetic field and monopole relationships

Abstract

In a recent study on monopole production [Eur. Phys. J. C (2018) 78: 966], Baines et al added the potential of a magnetic dipole to the Wu-Yang potentials for the Dirac monopole and claimed that this modified Wu-Yang configuration does not affect the Dirac quantisation condition. In this comment, we argue that their claim is incorrect by showing that their modified Wu-Yang configuration leads to an infinite number of quantisation conditions. In their study, they also incorrectly identified the magnetic field of the monopole with the magnetic field of the Dirac string and its attached magnetic monopole.