Exotic Pear-Shaped Atoms Hold Clues to Antimatter Mystery

The Big Bang is somewhat of a mystery to scientists. They have long wondered why during this critical point in our Universe's history, more matter than antimatter was created. Now, they've discovered a clue that may eventually provide the answer to that question. Researchers have found the first direct evidence of pear-shaped nuclei in exotic atoms.

The fact that the Big Bang created more matter than antimatter explains the origins of our very existence.  Antimatter is essentially the opposite of matter; they are particles that have the same mass but opposite charge from their matter counterparts.

"If equal amounts of matter and antimatter were created at the Big Bang, everything would have annihilated, and there would be no galaxies, stars plants or people," said Tim Chupp, a University of Michigan professor of physics and biomedical engineering, in a news release.

Antimatter itself is actually relatively rare in the known Universe, and researchers have long tried to examine the particles through various experiments. In fact, CERN's Large Hadron Collider is currently on a mission to further understand these mysterious particles.

The main issue with understanding the antimatter and matter imbalance is that it's not predicted by the Standard Model. This overarching theory describes the laws of nature and the nature of matter. More specifically, it describes four fundamental forces or interactions that govern how matter behaves; gravity attracts massive bodies to one another, the electromagnetic interaction gives rise to forces on electrically charged bodies and the strong and weak forces operate in the cores of atoms, binding together neutrons and protons or causing those particles to decay.

Since the Standard Model doesn't predict this imbalance, physicists have long sought another force or interaction that would explain it. Researchers in this latest study found that measuring how the axis of nuclei of radon and radium line up with the spin would actually help predict that balance. Why? They found that, surprisingly, the cores of these atoms are shaped like pears rather than being more sphere-like (like oranges) or elliptical (like watermelons). This particular pear shape makes the effects of the new interaction much stronger and easier to detect.

So why are they pear-shaped? The positive protons are pushed away from the center of the nucleus by nuclear forces, which are fundamentally different from spherically symmetric forces like gravity. This pear shape, in turn, would allow the researchers to view the effects of the new interaction.

"It produces the matter/antimatter asymmetry in the early universe and it aligns the direction of the spin and the charge axis in these pear-shaped nuclei," said Chupp in a news release. "Our findings contradict some nuclear theories and will help refine others."

The findings could allow scientists to eventually understand this imbalance in our Universe. In addition, the study could help direct the searches for atomic EDMs (electric dipole moments), where new techniques are being developed to exploit the special properties of radon and radium isotopes.

The findings are published in the journal Nature.