Particle physicists have obtained stunning results from B factories, the colliders that produce large numbers of particles including bottom quarks. They have confirmed many Standard Model predictions about the behavior of bottom quarks and the strong force. They have demonstrated the predicted asymmetry between matter and antimatter in quarks, but also shown that it is not enough to explain all the difference between matter and antimatter.
The success of those machines--the BaBar experiment on the PEP-II collider at Stanford Linear Accelerator Center, and the Belle experiment on the KEKB collider at KEK in Japan--led physicists to dream of more powerful devices which would push the intensity frontier, generating so many B mesons that the existence and effects of extremely rare particles would become evident. Generate enough collisions with high-intensity beams and these rare particles could provide the answer to where the Standard Model of particle physics is incomplete and breaks down, as physicists know it must.
The new breed of colliders would be called Super B factories. Two competing proposals in the works have gained considerable attention and will soon be ready for consideration by funding agencies. An excellent overview of these is in Science magazine, written by Adrian Cho.
The two competing proposals are an upgrade of the KEKB accelerator in Japan and a new machine that would be constructed in central Italy, near Frascati National Laboratory.
An interesting aspect of modern colliders is how closely any new project is connected with the rest of particle physics. Mostly gone are the days when a new collider just pushed for higher energy or with a new acceleration technique. New colliders fit tightly into the global suite of particle physics experiments, with complex interplay between them, and a true complementarity to their approaches. Our total understanding of particle physics is vastly more than simply the sum of the results from individual experiments.
The Super B factories show this very effectively. The results from the Super Bs would complement LHC results, being able to better find exquisitely rare particles that would be lost in the cloud of particles generated in each LHC collision. Those rare decays could also provide hints about physics at a much higher energy than the LHC's.
Super B factory design and construction would also be intimately connected with other particle accelerators. The PEP-II collider at SLAC, which closed down earlier this year, might provide about US$200 million worth of equipment as an in-kind contribution to the Italian project. Designs for a Super B factory could rely heavily on design work for the International Linear Collider's damping rings.
It is unlikely that both the Japanese and Italian colliders would proceed but the physics community should know in the next year or so which of these might be viable.
