# magnetic monopole mass

## July 12, 2017 19:43

Shortly after the publication of Dirac's seminal paper on the quantization of electric charge in 1931, experimenters began the search for magnetic monopoles. The result of the electric charge quantization meant that magnetic charge was known, but the mass of the monopole was not predicted and could be any value.

Over the years various estimates of monopole mass were made and experiments established limits on the mass. By the 1970s the lower limit on mass was established to be on the order of 5 GeV. Meanwhile in 1974 both t'Hooft and Polyakov found that grand unification involved magnetic monopoles and predicted a mass on the order of $$10^{16}$$ GeV. Since then studies have focused on the GeV range and greater.

Dirac's famous relation now known as the Dirac quantization condition

\begin{equation*} g = \dfrac{n\hslash c}{2e} = ng_D \quad\quad n = (0,\pm1,\pm2,\pm3,...), \end{equation*}