On the Dirac quantization condition

Abstract

We revisit the Dirac quantization condition for string-like and string-less (but multi-valued) magnetic monopole potentials. In doing so we allow for an {\it a priori} different coupling ${\tilde e}$ associated with the longitudinal components of the gauge potential. By imposing physical criteria in the choice of the longitudinal--transverse decomposition we show that -in contrast to some recent claims- the `unphysical' coupling $\tilde e$ does not appear in the quantization condition.