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Tiny discovery sheds light on Big Bang

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SNOWMASS VILLAGE, Colo. — By observing millions of subatomic particles called B mesons, a team of scientists working at the Stanford Linear Accelerator Center in California has found new evidence of a basic but subtle lopsidedness in nature that may explain why the universe contains mostly matter, rather than being virtually empty and devoid of stars, planets and people.

The results found by a multinational team of about 600 physicists and engineers were announced Friday in Stanford.

The lopsidedness is "extraordinarily tiny," Jonathan Dorfan, the director of the center, said at a meeting of physicists here. Nonetheless, he said, it may explain "a spectacularly interesting phenomenon, namely why we are here."

The asymmetry was first seen in 1964 by Val Fitch of Princeton University and James Cronin of the University of Chicago in an experiment for which they later received a Nobel Prize.

The effect was revealed in slight differences in the behavior of a given type of particle and its antimatter counterparts. Such differences may explain why the Big Bang explosion thought to have created the universe did not produce equal amounts of matter and antimatter, which then would have annihilated each other and left nothing but light.

But if matter and antimatter behaved differently in the cooling that followed the Big Bang, matter might have gradually begun to predominate in the universe. Physicists call these theorized differences charge-parity violation or CP violation.

But despite nearly 40 years of searching since the original experiment, physicists had been unable to show definitively that any other particles displayed CP violation. This left physicists to wonder whether the original discovery reflected some unexplained quirk or a basic natural law.

The new findings show with a statistical certainty of 99.997 percent that the effect also occurs in another type of particle, the B meson, the team says.

The experiment produced millions of B mesons and their antimatter counterparts, anti-B mesons, and observed the rates at which they decayed into other particles.

Slight differences in the decay rates of the matter and antimatter particles established CP violation "with a very high probability," said Gautier Hamel de Monchenault, a physicist at the Atomic Energy Commission in Saclay, France, and the physics analysis coordinator of BaBar.

Hamel de Monchenault said the degree of CP violation observed seemed generally in line with what physicists expected in the framework that physicists use to describe the fundamental particles and forces in the universe.