In particle physics, a B-factory, or sometimes a beauty factory,[1] is a particle collider experiment designed to produce and detect a large number of B mesons so that their properties and behaviour can be measured with small statistical uncertainty. Tauons and D mesons are also copiously produced at B-factories,

Two B-factories were designed and built in the 1990s. They are both based on electron-positron colliders with the centre of mass energy tuned to the ϒ(4S) resonance peak, which is just above the threshold for decay into two B mesons (both experiments took smaller data samples at different centre of mass energies). The Belle experiment at the KEKB collider in Tsukuba, Japan, and the BaBar experiment at the PEP-II collider at SLAC laboratory in California, United States, completed data collection in 2010 and 2008, respectively.[2]

The B-factories yielded a rich harvest of results, including the first observation of CP violation outside of the kaon system, measurements of the CKM parameters |Vub| and |Vcb|, measurements of purely leptonic B meson decays and searches for new Physics.

Proposals for next-generation B-factories include the canceled SuperB designed to be built in Frascati near Rome in Italy, and Belle II, an upgrade to Belle, which will begin operations in 2018.

See alsoEdit


  1. ^ J.T. Volk; et al. (1987). "Letter of Intent for a Tevatron Beauty Factory" (PDF). Fermilab Proposal #783.
  2. ^


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