A hint of matter and antimatter behaving differently to each other has been spotted in a new particle for the first time. If the find bears out, it could help explain the existence of all the matter in the universe, and why it was not snuffed out by antimatter long ago.
Physicists think that the big bang should have produced equal amounts of matter and antimatter. But these contrasting particles annihilate each other in a puff of energy whenever they meet, so they should have destroyed each other long ago.
The fact that there is enough matter in the universe today for us to exist and wonder why, means that some mechanism must have favoured matter over antimatter.
“Today we have this complete imbalance between matter and antimatter. We have no evidence of antimatter in the universe,” says Nicola Neri of the National Institute for Nuclear Physics in Milan, Italy. “This is one of the main questions we’d like to answer.”
One way the two could differ is by violating a rule about the way the laws of physics affect particles and antiparticles known as CP symmetry. Previously, experiments showed that CP symmetry is in fact violated in particles called mesons, which are made up of a quark and an antiquark. Those results garnered two Nobel prizes, one in 1980 and one in 2008.
But it wasn’t enough. “The sources we’ve found so far are not sufficient to explain this huge imbalance,” Neri says.
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