Antimatter

The standard model is the roadmap for this process, telling scientists which highways the B meson and the anti-B take on their trips through the subatomic equivalent of Europe, and how often they travel each one. The physicists are customs officials, checking to make sure the particles follow their assigned routes. Any deviation, however minute, implies that the standard model is either incomplete, incorrect, or inconsistent, and must be updated.


So B mesons are created and tracked in SLAC's underground tunnels and at a competing laboratory in Tsukuba, Japan. The work's recent success is, ironically, not the kind investigators were hoping for. They're finding roughly the degree of CP violation that the standard model predicts-and that's simply not enough, by a factor of a billion. If the standard model is correct, for every billion stars in today's universe, there should be only one. One billion times fewer worlds capable of developing life. Our chances of evolving out of swamp juice on this planet, minuscule to begin with, would have been reduced by another factor of a billion. "One thing we know for sure is that the standard model by itself can't give enough (of a) difference between matter and antimatter for us to have survived," says Hitoshi Murayama, professor at the University of California, Berkeley.


I'm standing on a catwalk inside the SLAC accelerator, where scientists recreate the environment of the early universe. Smith is explaining how a typical measurement is made. "The electrons come through here," he says, pointing to a narrow tube entering from the far side of the room. Positrons, the antimatter partners of electrons, emerge from the wall directly across, and the two meet head-on inside the monolith before me, traveling at nearly the speed of light. Sometimes the collision creates both a B and an anti-B, and the detector takes what is effectively a snapshot of the collision's aftermath. As particles burst from the center of the detector, they burn their image into its multiple concentric shells. The innermost one, a device called a silicon vertex detector, is somewhat like photographic film, but made of silicon and sensitive to the slightest differences in position. The data created here is fed to vast banks of electronics, then crunched in computers around the world in a months-long analysis.


What Smith and others hope for, in their heart of hearts, is inconsistency. They want to discover, say, that the B meson rests in Paris for a week, when the standard model predicts it finishes the trip in just four days. In short, they want to find the chink in the standard model's armor.