WHEN the universe was created in the big bang, matter and antimatter were present in equal quantities. But along the way, the antimatter seems to have disappeared. The discovery of a rare process that destroys antimatter faster than matter hints at an answer to the mystery.
The effect was uncovered during an experiment called BaBar at the Stanford Linear Accelerator Center in Menlo Park, California. Researchers found a massive difference in the decay rate of two types of fundamental particles, the bottom quark and its antimatter equivalent, the anti-bottom quark.
These are constituents of another particle, the B meson, which BaBar produces in abundance. After sifting the data from 200 million decays of B mesons, the team found 910 instances of the particle containing the anti-bottom quark decaying into other particles, while this happened only 696 times for B mesons with a bottom quark.
Advertisement
The difference in decay rates is about 100,000 times greater than anything found before. 鈥淭heoretically, there is the possibility of having these large asymmetries, but we鈥檝e never, ever seen them before,鈥� says Daniel Bowerman from Imperial College in London, one of around 600 scientists in the BaBar collaboration.
The effect seen in the B mesons falls within the predictions made by the standard model of particle physics, which cobbles together everything we know so far about particles and the forces that glue them together. However, the differential decay rate is still not large enough to explain why the antimatter created in the big bang vanished, before it could interact with matter and make both disappear in a flash of photons.