Physicists have long suspected the existence of magnetic monopoles – particles that possess either a north or south pole without their counterpart. While these elusive monopoles have yet to be found, new data from the Large Hadron Collider (LHC) has allowed researchers to narrow down the possible energy-space where magnetic monopoles may reside.
The concept of magnetic monopoles was originally proposed by physicist Paul Dirac. He suggested that the presence of magnetic monopoles would be consistent with quantum mechanics and could explain certain unexplained features of charge. According to Dirac’s theory, the smallest possible magnetic charge for a single monopole is 68.5 times the charge on an electron, with larger monopoles being multiples of that.
In the 1970s, the search for magnetic monopoles gained momentum as it became a key test for theories that aimed to unify general relativity and quantum mechanics. While reports of the discovery of magnetic monopoles have occasionally surfaced, they have often been withdrawn or cases of misreporting.
The ATLAS collaboration at CERN, using data from the LHC, has identified two possible mechanisms by which high-energy collisions between protons could create magnetic monopoles with masses up to 4 TeV. Both mechanisms involve the release of virtual photons by the protons. In one scenario, a virtual photon creates a magnetic monopole on its own, and in the other, two photons interact to create a monopole. Either of these scenarios would restore the broken electric-magnetic dual symmetry in Maxwell’s equations.
ATLAS is searching for evidence of magnetic monopoles by looking for charge deposits on their detector. Since a monopole would carry a charge much greater than that of an electron, its deposits should stand out from those of other subatomic particles.
Although ATLAS has not yet found direct evidence of magnetic monopoles, their analysis of LHC data from 2015-2018 has allowed them to narrow down the possible masses and rate of production for the smallest monopoles by a factor of three.
While it may seem like an endless quest, the physics community believes in the importance of finding magnetic monopoles. Not only would their discovery validate theories predicting their existence, but the masses of these monopoles could also differentiate between competing theories.
The research paper discussing these findings has been submitted to the Journal of High Energy Physics and is available as a preprint on ArXiv.org.
– CERN (ATLAS collaboration)
– Journal of High Energy Physics (preprint)