Particles that bridge the two worlds, such as the B sub s meson, normally don't exist on their own but can be created in the great collisions generated by particle accelerators, which attempt to duplicate conditions close to the Big Bang. Studying the particles helps scientists understand the evolution of the universe.

Fermilab's Tevatron collides protons against antiprotons moving near the speed of light, producing about 10 million collisions a second. The key to interpreting this enormous amount of data is the CDF detector, a three-story-high instrument that measures the tracks of the particles exploding from the collisions.

Such experiments are big and expensive and require huge work forces. The meson experiment involves 700 physicists from 61 institutions and 13 countries.

Fermilab physicists are now more hopeful they may be able to find signs of even more elusive particles, such as the Higgs particle, which imbues matter with mass. Without the Higgs, it is theorized, matter would have no weight.

"We hope we will see either signs of the Higgs or the discovery of new physics," said University of Chicago physicist Ivan Furic, who called the new discovery "a morale booster."

"The options are still there," he said. "The Tevatron is still taking data."

"If there are unexpected types of particles that can communicate between matter and antimatter this is a very good place to find them," said team co-leader Jacobo Konigsberg, of the University of Florida. "It helps us see if there is room for even more exotic particles that can occur in nature, but they occur in such subtle ways that we are not aware of them."