From Voice of America News:
Scientists at Vanderbilt University believe dark matter, an invisible substance that makes up almost 85 percent of our universe, might be made out of particles that have an unusual, donut-shaped electromagnetic field called an anapole.* * *The two physicists believe dark matter might be made out of a type of elementary electrically neutral particle called the Majorana fermion (or Majorana Particle). The existence of this particle was predicted by Italian physicist Ettore Majorana in 1937, but has so far escaped detection.* * *
The Majorana fermions are difficult to detect, according to Scherrer and Ho, because this anapole field gives the particles certain properties that make them quite different from others that have more common fields comprised of two poles – north and south, positive and negative.
“Most models for dark matter assume that it interacts through exotic forces that we do not encounter in everyday life,” said Scherrer. “Anapole dark matter makes use of ordinary electromagnetism that you learned about in school: the same force that makes magnets stick to your refrigerator or makes a balloon rubbed on your hair stick to the ceiling. Further, the model makes very specific predictions about the rate at which it should show up in the vast dark matter detectors that are buried underground all over the world. These predictions show that soon the existence of anapole dark matter should either be discovered or ruled out by these experiments.”
Scientists developed the concept of dark matter in the 1930s, while trying to explain discrepancies in the rotational rate of galactic clusters. Since then, astronomers have also found similar inconsistencies in the rate at which stars rotate around individual galaxies. Assuming they contain a large amount of invisible dark matter is the most straightforward way to explain these discrepancies.