Magnetic monopole as a spacetime defect

Abstract

We propose that the only possible realization of a magnetic pole is emergent, it being an artifact of a torsion defect in a curved spacetime. This special phase is built upon a class of degenerate metric spacetime solutions of first-order gravity in vacuum. The (apparent) magnetic charge is shown to have a topological origin, given by a lower-dimensional counterpart of the Nieh-Yan invariant. At the invertible metric phase at a distance, this topological charge gets reflected as the (magnetic) Reissner-Nordstr\"om charge to an asymptotic observer, even though the monopole defect itself remains hidden.