B-Bbar oscillation
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The existence of neutral B meson oscillations is a fundamental prediction of the standard model of particle physics. The theory predicts that the neutral B mesons will change form between their matter and antimatter forms before the B decays.
[edit] The B-Factories
The observation of the B-Bbar mixing phenomena led physicists to propose the construction of B-factories in the early 1990s. They realized that a precise B-Bbar oscillation measure could pin down the unitarity triangle and perhaps explain the excess of matter over antimatter in the universe. To this end construction began on two B-factories in the late nineties, one at the Stanford Linear Accelerator Center (SLAC) in California and one at KEK in Japan. These B-factories, BaBar and Belle, were set at the Upsilon(4S) resonance which is just above the threshold for decay into two B mesons. After several years they confirmed that the standard model was correct to high precision in this area.
[edit] Bs Oscillations
The Bs meson can exist as either a bound state of a anti-strange and bottom quark, or a strange and anti-bottom quark. The oscillations in the neutral B sector are analogous to the phenomena that produces long and short-lived neutral kaons. Bs mixing was observed by the CDF experiment at Fermilab in 2006 .
