Status of Searches for Magnetic Monopoles
The searches for magnetic monopoles (Ms) is a fascinating interdisciplinary field with implications in fundamental theories, in particle physics, astrophysics, and cosmology. The quantum theory of Ms and its consistency with electrodynamics was derived by Dirac. This marked the start of the searches for classical monopoles at every new accelerator, up to the LHC. Magnetic monopoles are required by Grand Unification Theories, but unlike classical monopoles they would be incredibly massive, out of the reach of any conceivable accelerator. Large efforts have been made to search for them in the cosmic radiation as relic particles from the early Universe in the widest range of mass and velocity experimentally accessible. In this paper the status of the searches for classical Ms at accelerators, for GUT, superheavy Ms in the penetrating cosmic radiation and for Intermediate Mass Ms at high altitudes is discussed, with emphasis on the most recent results and future perspectives.