From ScienceDaily:
The stability of dark matter is usually explained by a symmetry principle. However, in their paper, Dr. Michael Baker and Prof. Joachim Kopp demonstrate that the universe may have gone through a phase during which this symmetry was broken. This would mean that it is possible for the hypothetical dark matter particle to decay. During the electroweak phase transition, the symmetry that stabilizes dark matter would have been re-established, enabling it to continue to exist in the universe to the present day.
With their new theory, Baker and Kopp have introduced a new principle into the debate about the nature of dark matter that offers an alternative to the widely accepted WIMP theory. Up to now, WIMPs, or weakly interacting massive particles, have been regarded as the most likely components of dark matter, and experiments involving heavily shielded underground detectors have been carried out to look for them. “The absence of any convincing signals caused us to start looking for alternatives to the WIMP paradigm,” said Kopp.
The two physicists claim that the new mechanism they propose may be connected with the apparent imbalance between matter and antimatter in the cosmos and could leave an imprint which would be detected in future experiments on gravitational waves. In their paper published in the scientific journal Physical Review Letters, Baker and Kopp also indicate the prospects of finding proof of their new principle at CERN’s LHC particle accelerator and other experimental facilities. Paper. (paywall) – Michael J. Baker, Joachim Kopp. Dark Matter Decay between Phase Transitions at the Weak Scale. Physical Review Letters, 2017; 119 (6) DOI: 10.1103/PhysRevLett.119.061801 More.
It would really help if we could find a particle of dark matter. Theory only takes us only far when we are discussing a world of evidence.
See also: Rob Sheldon on a big current question: Is dark matter real?