#26: How Matter Defeated Antimatter

By Andrew Grant|Thursday, December 16, 2010

The Big Bang theory has a Big Problem. The leading models of cosmology imply that the universe should have begun with equal quantities of matter and antimatter. But when the two meet, they annihilate each other, so an equal balance would have yielded an empty cosmos. In May, physicists at the Tevatron particle accelerator in Illinois singled out a strange particle that could help explain the conundrum.

Studying nearly eight years’ worth of high-speed smashups between protons and antiprotons, Guennadi Borissov of Lancaster University in the U.K. and other members of the Tevatron team focused on the B meson, a short-lived particle that emerges from the collisions. During its brief life, this particle rapidly oscillates between matter and antimatter: One moment it’s a B meson, the next it’s an anti-B meson. This constant wavering should create just as many anti-B mesons as B mesons, but the physicists discovered a clear bias for the matter variety—50.5 percent matter to 49.5 percent antimatter.

Follow-up experiments planned for this year at both the Tevatron and the Large Hadron Collider will test the team’s findings. If they are verified, theorists will have an important clue about where the symmetry laws predicted by the standard model of physics break down. They will also have the basis for a new theory explaining the pro-matter bias in the rules that jump-started our universe 13.7 billion years ago. “This will give a very strong push toward finding an answer to one of the most fundamental questions in physics,” Borissov says.

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