Beyond WIMPs: Exploring Alternative Theories Of Dark Matter

Image from Dark Universe, showing the distribution of dark matter in the universe. Credit: AMNH

The standard model of cosmology tells us that only 4.9% of the Universe is composed of ordinary matter (i.e. that which we can see), while the remainder consists of 26.8% dark matter and 68.3% dark energy. As the names would suggest, we cannot see them, so their existence has had to be inferred based on theoretical models, observations of the large-scale structure of the Universe, and its apparent gravitational effects on visible matter.Since it was first proposed, there have been no shortages of suggestions as to what Dark Matter particles look like. Not long ago, many scientists proposed that Dark Matter consists of Weakly-Interacting Massive Particles (WIMPs), which are about 100 times the mass of a proton but interact like neutrinos. However, all attempts to find WIMPs using colliders experiments have come up empty. As such, scientists have been exploring the idea lately that dark matter may be composed of something else entirely. Current cosmological models tend to assume that the mass of dark matter is around 100 Gev (Giga-electrovolts), which corresponds to the mass scale of a lot of the other particles that interact via weak nuclear force. The existence of such a particle would be consistent with supersymmetric extensions of the Standard Model of particle physics. It is further believed that such particles would have been produced in the hot, dense, early Universe, with an a matter mass-density that has remained consistent to this day.However, ongoing experimental efforts to detect WIMPs have failed to produce any concrete evidence of these particles. These have including searching for the products of WIMP annihilation (i.e. gamma rays, neutrinos and cosmic rays) in nearby galaxies and clusters, as well as direct detection experiments using supercolliders, like the CERN Large Hardon Collider (LHC) in Switzerland.Because of this, many researcher teams have —> Read More