New Model for Dark Matter May Solve Long-Standing Issues

Scientists may have come up with a novel model of dark mater, the mysterious substance that makes up about 80 percent of our universe. The findings could shed new light on the nature of dark matter and show the path for future research.

"Dark matter has not yet been detected in a lab," said Mikhail Medvedev, one of the researchers, in a news release. "Dark matter is some unknown matter, most likely a new elementary particle or particles beyond the Standard Model. It has never been observed directly, but it reveals itself via gravity it produces in the universe. There are numerous experiments around the world aimed at finding it directly."

The new model of dark matter has been dubbed "flavor-mixed multicomponent dark matter." The theory rests on the behavior of elementary particles that have been observed or hypothesized. According to today's prevalent Standard Model of particle physics, elementary particles are the building blocks of an atom. The properties of quarks and leptons, which are elementary particles, are prone to change back and forth since they can combine with each other in a phenomenon called flavor-mixing.

It's also theorized that dark matter candidates could be flavor-mixed, such as neutralinos, axions and sterile neutrinos. Previously, scientists discovered that flavor-mixed particles can "quantum evaporate" from a gravitational well if they collide with another particle. That's why the researchers included the physical process of quantum evaporation in a "cosmological numerical code" and performed simulations.

Dark matter may interact with normal matter extremely weakly, which is why it hasn't been revealed already in numerous ongoing direct detection experiments around the world. That's why physicists have devised a working model of completely noninteracting, cold dark matter with a cosmological constant, which they've dubbed the "Lambda-CDM model." Yet this model hasn't always agreed with observational data. The new model in this latest research, though, solves some of the old model's issues.

"Our results demonstrated that the flavor-mixed, two-component dark matter model resolved all the most pressing Lambda-CDM problems simultaneously," said Medvedev.

The findings are published in the journal Physical Review Letters.