Belle experiment

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The Belle Experiment is a particle physics experiment conducted by the Belle Collaboration, an international collaboration of more than 400 physicists and engineers investigating CP-violation effects at the High Energy Accelerator Research Organisation (KEK) in Tsukuba, Ibaraki Prefecture, Japan.

The Belle detector, located at the collision point of the experiment, is a multi-layer particle detector. Its large solid angle coverage, vertex location with precision on the order of tens of micrometres (provided by a silicon vertex detector), good pion-kaon separation at multi-GeV momenta (provided by a novel Cherenkov detector), and few-percent precision electromagnetic calorimetry (CsI(Tl) scintillating crystals) allow a list of other scientific searches apart from CP-violation. Extensive studies of rare decays, searches for exotic particles and precision measurements of bottom and charm mesons and tau lepton have been carried out and have resulted in over 180 publications in physical journals.

Highlights of the Belle experiment so far include the 1st observation of CP violation outside of the kaon system (2001), osbervation of B->K(*) l^+ l^- and b->s l+ l-, measurement of phi_3 using the B->D K, D->K_S pi^+ pi^- Dalitz plot, observation of direct CP violation in B^0->pi^+ pi^- and B^0->K^- pi^+, observation of b->d transitions and evidence for B->tau nu as well as observations of a number of new particles including the X(3872).

The Belle experiment operates at the KEKB accelerator, the world's highest luminosity machine. The instantaneous luminosity exceeds 1.6 x 10^34/cm^2/sec. The integrated luminosity is greater than 600 fb^-1 (in excess of 600 million B Bbar meson pairs).

Plans for a Super B-factory, an upgraded facility with two orders of magnitude more luminosity are now under discussion.